A process for the purification of an aqueous stream comprising e-caprolactam

Abstract

A process for the purification of an aqueous stream comprising ε-caprolactam, comprising (i) providing an aqueous stream S0 comprising ε-caprolactam, one or more organic compounds X and one or more organic compounds Y; (ii) separating water from the stream S0, comprising a distillation in a first distillation column D1, obtaining from D1 a va- pour top stream ST1 and a liquid bottoms stream SB1 comprising ε-caprolactam, the one or more organic compounds X at a total concentration and the one or more organic compounds Y; (iii) separating the one or more compounds X from at least a part of the stream SB1, comprising a distillation in a second distillation column D2, obtaining from D2 a top stream ST2 comprising ε-caprolactam and the one or more organic compounds Y, a bottom stream SB2 compris- ing the one or more organic compounds X, and a side stream SS2 comprising ε-caprolactam; (iv) separating the one or more compounds Y from at least a part of the stream ST2, comprising a distillation in a third distillation column D3, obtaining from D3 a top stream ST3 comprising the one or more compounds Y and a bottom stream SB3 comprising ε- caprolactam.

Description

A process for the purification of an aqueous stream comprising E-caprolactamThe present invention relates to a process for the purification of an aqueous stream comprising E-caprolactam three serially arranged distillation steps.Polyamide, and in particular polyamide 6 characterized by the formula (-NH-(CH2)5-CO-)n, can be found in numerous materials, such as packaging, engineering plastics from automotive and textile filaments. The latter represents about 40 % of the polyamide 6 global market. At present, only a very small part of the textile filaments is recycled while it represents a significant percentage of the global CO2 emissions. There is thus a need to recycle polyamide 6 from such materials.Such recycling suitably involves subjecting materials containing polyamide 6, in particular textile materials, to a depolymerization stage and subjecting the respectively obtained crude depolymerization mixture comprising E-caprolac- tam to downstream purification. Such purification process for E-caprolactam downstream of the depolymerization step is not a straightforward task, for example due to the various possible chemical compositions of waste materials comprising polyamide 6 which form the educt materials for the recycling process.US 7,501 ,047 B2 relates to a process for purifying crude caprolactam. The process involves converting a first mixture of 6-amino capronitrile and water to a second mixture of caprolactam ammonia, water, high boilers and low boilers using a catalyst. The ammonia is removed from the second mixture to obtain a third mixture. Water is removed from the third mixture to give crude caprolactam, high boiler and low boilers.WO 2003 / 045911 A discloses a process for recovering caprolactam from a mixture comprising caprolactam, water, light and heavy components, by subjecting the mixture to a first vacuum distillation resulting in a first bottom product comprising heavy components and caprolactam and in a first overhead product comprising caprolactam, water, unsaturated lactams and light components; and subjecting at least part of the unsaturated lactams to a hydrogenation.According to the present invention, it was found that a distillation stage comprising three serially arranged distillation steps significantly contributes to solving this problem. Further according to the present invention, it was found that this distillation stage is even more advantageous if it includes, in particular after the first distillation stage, a chemical treatment step. The thus provided process may lead to, depending on the composition of the stream subjected to the distillation stage, a finally purified E-caprolactam stream which can be used, without any further purification, as a starting material for the re-polymerization of polyamide 6. In case, however, the purified E-caprolactam stream may not lead to a suitable starting material, the process of present invention includes, as a preferred downstream stage, a suitable crystallization stage. Thus, the process of the present invention is capable of leading to a starting material for re-polymerization of polyamide 6, irrespective of the composition of the polyamide 6 material to be recycled and irrespective of the specification of the E-caprolactam stream to be subjected to re-polymerization.Therefore, the present invention relates to a process for the purification of an aqueous stream comprising E-capro- lactam, the process comprising(i) providing an aqueous stream So comprising E-caprolactam at a concentration Cso(C), one or more organic compounds X at a total concentration Cso(X), one or more organic compounds Y at a total concentration cso(Y), and water at a concentration Cso(W), wherein water has a boiling point Tw, E-caprolactam has a boiling temperature Tc, the one or more organic compounds X have a boiling temperature Tx, and the one or more organic compounds Y have a boiling temperature Ty, with Ty < Tc < Tx;(ii) separating water from the stream So, comprising a distillation in a first distillation column D 1, obtaining from Di a vapour top stream STI comprising water at a concentration CSTI(W) > Cso(W), and further obtaining from Di a liquid bottoms stream SBI comprising E-capro-lactam at a concentration CSBI(C) > Cso(C), the one or more organic compounds X at a total concentration CSBI(X) > cso(X), and the one or more organic compounds Y at a total concentration CSBI(Y) > cso(Y);(iii) separating the one or more compounds X from at least a part of the stream SBI, comprising a distillation in a second distillation column D2, obtaining from D2 a top stream ST2 comprising E-caprolactam at a concentration CST2(C) < CSBI(C) and the one or more orga-nic compounds Y at a total concentration CST2(Y) > CSBI(Y), further obtaining from D2 a bottom stream SB2 comprising the one or more organic compounds X at a total concentration CSB2(X) > CSBI(X) and optionally E-caprolactam at a concentration CSB2(C) < CSBI(C), and obtaining from D2 a side stream Ss2 comprising E-caprolactam at a concentration css2(C) > CSBI(C);(iv) separating the one or more compounds Y from at least a part of the stream ST2, comprising a distillation in a third distillation column D3, obtaining from D3 a top stream STS comprising the one or more compounds Y at a total concentration CST3(Y) > CST2(Y), and obtaining from D3 a bottom stream SB3 comprising E-caprolactam at a concentration CSB3(C) > CST2(C).Unless defined differently in the context of the present invention, the term "E-caprolactam” as used herein refers to monomeric E-caprolactam.The stream SoWith regard to the stream So, it is preferred that from 98 to 100 weight-%, more preferably from 99 to 100 weight-%, more preferably from 99.5 weight-%, more preferably from 99.8 to 100 weight-% of this stream So consist of E-capro- lactam, the one or more compounds X, the one or more compounds Y, and water.In the stream So, the weight ratio of E-caprolactam relative to water, m(C) / m(W), is preferably in the range of from 1.5: 1 to 10: 1 , more preferably in the range of from 2:1 to 9.5:1 , more preferably in the range of from 2.5: 1 to 9:1.Further preferably, from 0.1 to 8 weight-%, more preferably from 0.2 to 7 weight-%, more preferably from 0.5 to 6weight-% of the stream So consist of the one or more compounds X and the one or more compounds Y. It is conceivable that from 0.1 to 5 weight-%, preferably from 0.2 to 4 weight-%, more preferably from 0.5 to 3 weight-% of the stream So consist of the one or more compounds X and the one or more compounds Y.Preferably, the stream So is a vapour stream, preferably having a pressure in the range of 75 to 125 mbar(abs) and, at this pressure, preferably having a temperature in the range of from 150 to 250 °C, more preferably in the range of from 155 to 200 °C, more preferably in the range of from 160 to 175 °C.Regarding the chemical nature of the high-boiler compounds X, a comparatively high uncertainty exists, simply in view of the unpredictable chemical composition of the materials subjected to depolymerization as described herein. However, when developing the process of the present invention, numerous elaborate experiments were carried out, and it was found that in a majority of situations, the one or more compounds X preferably comprise at least one of 1- cyclopentene carboxylic acid; 3-cyclopentene carboxylic acid; 2-butyl-2-ethyl-1 ,3-propandiol; 2-hydroxyethyl-6-hy- droxyhexane carboxylic acid ethyl ester; 2-naphthol, 1-cyclopentylazepane-2-on; 1 -hexadecanol (cetyl alcohol); 1- octadecanol (stearyl alcohol); 6-hydroxy-N-(2,2,6,6-tetramethyl piperidine-4-yl)hexane amide; 1 ,8-diazacyclo-tetrade- cane-2,9-dion; MDA; di-(4-aminophenyl)-methane; 2,4-diaminodiphenylmethane; N-cyclopentylcaprolactam; 1-ben- zylazepane-2-on; tetrabutylene glycol; 7-hydroxyazepane-2-on; phthalic acid monomethyl ester; nonane diacid; and terephthalic acid.Regarding the chemical nature of the low-boiler compounds Y, a comparatively high uncertainty exists, simply in view of the unpredictable chemical composition of the materials subjected to depolymerization as described herein. However, when developing the process of the present invention, numerous elaborate experiments were carried out, and it was found that in a majority of situations, the one or more compounds Y preferably comprise at least one of at least one of 1-methoxypropane, neopentylglycol, 2,2-dimethylpropane-1,3-diol; 2-methylpropane-1,3-diol, aniline, 2, 2,6,6- tetramethylpiperidine; 2,3,5,6-tetramethylpiperidin; 2-chloroaniline; caprolactone; N-methylcaprolactame; N-methyl- caprolactame; N-propylcaprolactame; 1-dodecanol; hexahydro-2-oxo-1 H-azepin-1-propanal; hexahydro-2h-azepin-2- one; 2-hydroxyethyl-6-hydroxyhexane carboxylic acid ester; 7-hydroxy-N-(2,2,6,6-tetramethyl piperidine-4-yl) heptan- amide; 2-aminoethanol; N-methylbenzolamine; 2,3,5,6-tetramethylpiperidine; N-methylbenzolamine; 2-hydroxy-n- methylacetamide; 2-oxo-azepane-1-carbaldehyde; N-methylacetamide; 2-methoxy-n-methylcyclohexan-1-amine; 2- hydroxy-N-methylacetamide; and 7-hydroxyazepane-2-one.Distillation in DiThe distillation in Di according to (II) is carried out at a temperature TDI at the bottom of Di and at pressure PDI at the top of Di, wherein PDI is preferably in the range of 75 to 125 mbar(abs) and TDI is preferably in the range of 100 to 120 °C, more preferably in the range of 105 to 120 °C, more preferably in the range of 110 to 120 °C.Further, the distillation in Di according to (ii) is preferably carried out at a reflux ratio which is preferably in the range of from 0.2:1 to 0.9:1, more preferably in the range of from 0.3:1 to 0.8:1, wherein the reflux ratio is defined as the mass flow ratio of the stream passed back to the top of Di relative to the stream So.Preferably at least 75 weight-%, more preferably at least 80 weight-%, more preferably at least 85 weight-% of the stream STI obtained at the top of Di consist of water and optionally a part of the one or more compounds Y with Ty Tw. It is conceivable that at least 90 weight-%, preferably at least 95 weight-% of the stream STI obtained at the top of Di consist of water and optionally a part of the one or more compounds Y with Ty < Tw. Further preferably, at most 500 weight-ppm, more preferably at most 200 weight-ppm, more preferably at most 100 weight-ppm of the stream STI obtained at the top of Di consists of E-caprolactam.Preferably from 98 to 100 weight-%, more preferably from 99 to 100 weight-%, more preferably from 99.5 weight-%, more preferably from 99.8 to 100 weight-% of the stream SBI consist of E-caprolactam, the one or more compounds X, the one or more compounds Y, and water, wherein preferably at most 5 weight-%, more preferably at most 2 weight-%, more preferably at most 1 weight-% of the stream SBI consist of water.Preferably, the distillation in Di comprises subjecting the liquid bottom stream SBI having the temperature TDI to heating in a reboiler RDI, obtaining from RDI a vapour stream SBW and a liquid stream SBIL, the streams SBW and SBIL having a temperature TDI+ATDI, wherein ATDI is preferably in the range of from 5 to 15 K, wherein the stream SBW and preferably a part of the stream SBIL are passed back into the bottoms section of Di and the stream SBIL, preferably a part of the stream SBIL, is passed to (iii). Said reboiler RDI is preferably configured as a film evaporator, more preferably as a falling film evaporator. Preferably from 98 to 100 weight-%, more preferably from 99 to 100 weight-%, more preferably from 99.5 weight-%, more preferably from 99.8 to 100 weight-% of the stream SBIL consist of s-ca- prolactam, the one or more compounds X, the one or more compounds Y, and water, wherein more preferably at most 5 weight-%, more preferably at most 2 weight-%, more preferably at most 1 weight-% of the stream SBI L consist of water.Distillation in D2The distillation in D2 according to (iii) is carried out at a temperature TD2 at the bottom of D2 and at pressure pD2 at the top of D2, wherein pD2 is preferably in the range of from 2 to 8 mbar(abs), more preferably pD2 PDI and preferably TD2 > TDI, TD2 more preferably being in the range of from 110 to 160 °C, more preferably in the range of from 120 to 150 °C, more preferably in the range of from 130 to 140 °C.Further, the distillation in D2 according to (iii) is preferably carried out at a reflux ratio which is preferably in the range of from 0.5:1 to 1.5:1, more preferably in the range of from 0.6:1 to 0.9:1, more preferably in the range of from 0.7:1to 0.9:1 , wherein the reflux ratio is defined as the mass flow ratio of the stream passed back to the top of D2, relative to the stream SBI, preferably SBIL.Preferably at least 97 weight-%, more preferably at least 98 weight-%, more preferably at least 99 weight-% of the stream ST2 obtained at the top of D2 consist of E-caprolactam and the one or more compounds Y, wherein in the stream ST2, the weight ratio of E-caprolactam relative to the one or more compounds Y, m(C) / m(Y), is preferably at most 40: 1 , more preferably at most 30: 1 , more preferably at most 20: 1 . Further preferably, at most 97 weight-%, more preferably at most 96 weight-%, more preferably at most 95 weight of the stream ST2 obtained at the top of D2 consist of E-caprolactam.Preferably at least 97 weight-%, more preferably at least 98 weight-%, more preferably at least 99 weight-% of the stream SB2 obtained at the bottom of D2 consist of E-caprolactam, the one or more compounds X and optionally the one or more compounds Y, wherein in the stream SB2, the weight ratio of E-caprolactam relative to the one or more compounds , m(C) / m(x), is preferably at most 10: 1 , more preferably at most 7: 1 , more preferably at most 4:1.According to the present invention, preferably at least 95 weight-%, more preferably at least 98 weight-% of the stream Ss2 obtained at the side of D2 consist of E-caprolactam. In this context, preferably from 95 to less than 99 weight-%, more preferably from 98 to less than 99 weight-% of the stream Ss2 obtained at the side of D2 may consist of E-caprolactam.Further according to the present invention, it is preferred that at least 99 weight-%, preferably at least 99.5 weight-%, more preferably at least 99.9 weight-% of the stream Ss2 obtained at the side of D2 consist of E-caprolactam.Distillation in D3The distillation in D3 according to (iv) is carried out at a temperature TD3 at the bottom of D3 and at pressure pD3 at the top of D3, wherein pD3 is preferably in the range of from 5 to 12 mbar(abs), more preferably pD3 pD2, more preferably PD3 > PD2, and preferably TD3 > TD2, TD3 more preferably being in the range of from 120 to 150 °C, more preferably in the range of from 130 to 150 °C, more preferably in the range of from 140 to 150 °C.Preferably, the distillation in D3 according to (iv) is carried out at a reflux ratio, preferably in the range of from 0.6:1 to 0.95:1 , more preferably in the range of from 0.7:1 to 0.95: 1 , more preferably in the range of from 0.8:1 to 0.95: 1 , wherein the reflux ratio is defined as the mass flow ratio of the stream passed back to the top of D3 relative to the stream ST2.Preferably at least 97 weight-%, preferably at least 98 weight-%, more preferably at least 99 weight-% of the stream STS obtained at the top of D3 consist of E-caprolactam and the one or more compounds Y, wherein in the stream ST3,the weight ratio of E-caprolactam relative to the one or more compounds Y, m(C) / m(Y), is preferably at most 9: 1 , more preferably at most 7:1, more preferably at most 5:1.Preferably at least 98 weight-%, more preferably at least 99 weight-%, more preferably at least 99.5 weight-% of the stream SB3 obtained at the bottom of D3 consist of E-caprolactam and optionally the one or more compounds Y, wherein in the stream SB3, the weight ratio of E-caprolactam relative to the one or more compounds Y, m(C) / m(Y) is preferably at least 99:1, more preferably at least 99.5:11, more preferably at least 99.8:1, more preferably at least 99.9:1.According to the present invention, it is possible to react in a flexible manner to specific compositions of the stream SB3. If, for example, the weight ratio in the stream SB3 of E-caprolactam relative to the one or more compounds Y, m(C) / m(Y), is greater than or equal to a pre-defined threshold value, the process further comprises(v.1) passing at least a part of the stream SB3 obtained at the bottom of the distillation column D3 to a downstream treatment stage, said downstream treatment stage preferably comprising a crystallization.Further, for example, if it turns out that in the stream SB3, the weight ratio of E-caprolactam relative to the one or more compounds Y, m(C) / m(Y), is below a pre-defined threshold value, the process further comprising(v.2) passing at least a part of the stream SB3 obtained at the bottom of the distillation column D3 to an upstream treatment stage, said upstream treatment preferably comprising the distillation in the distillation column D2, wherein more preferably, the at least a part of the stream SB3 is passed to the top of the distillation column D2.According to the process of the present invention, it is especially preferred that it comprises(v.3) passing at least a part of the stream Ss2 obtained at the side of the distillation column D2 to a downstream treatment stage, said downstream treatment stage preferably comprising a crystallization.Further according to the process of the present invention, it may be preferred that(v.4) at least a part of a stream obtained from condensing the stream Ss2 obtained at the side of the distillation column D2 is passed to an upstream treatment stage, said upstream treatment preferably comprising the distillation in the distillation column D2, wherein more preferably, the at least a part of the stream STS is passed to the top of the distillation column D2.Chemical treatmentAs mentioned hereinabove, it was found that this distillation stage is even more advantageous if it includes, in particular after the first distillation stage, a chemical treatment step.According to this chemical treatment stage, the at least a part of the stream SBI obtained according to (ii), preferably the stream SBIL as defined in any one of embodiment 13 to 15, comprises one or more oxidizable organic impurity compounds Z. Preferably downstream of separating water from the stream So according to (ii) and more preferably upstream of separating the one or more compounds X from at least a part of the stream SBI according to (ill), the process then further comprises subjecting the at least a part of the stream SBI, preferably the stream SBI L as defined herein, to a chemical treatment stage, obtaining from said chemical treatment stage a chemically treated part of the stream SBI, preferably a chemically treated stream SBIL, which is then passed to separating the one or more compounds X according to (ill).Generally, it is possible that the one or more oxidizable compounds Z are one or more compounds of the group of the one or more compounds X and / or one or more compounds of the group of the one or more compounds Y. In particular, regarding the chemical nature of the one or more oxidizable compounds Z, a comparatively high uncertainty exists, simply in view of the unpredictable chemical composition of the materials subjected to depolymerization as described herein. However, when developing the process of the present invention, numerous elaborate experiments were carried out, and it was found that in a majority of situations, the one or more compounds Z preferably comprise one or more of diol compounds such as ethylene glycol, diethylene glycol, 1 ,4-butanediol, neopentylglycol, 2-methyl-1 ,3-pen- tanediol; aromatic alcohols and amines such as phenol, o- toluidine, m- toluidine, p-toluidine, aniline, diamino toluenes; aliphatic amines such as hexamethylene diamine, 4-amino-2,2,6,6-tetramethyl-piperidin, 2,2,6,6-tetramethyl- piperidine, bis[2-(N,N-dimethylamino)-ethyl]ether.Preferably, the chemical treatment stage comprises(a) providing a stream Sox comprising at least one oxidizing agent preferably comprising a permanganate;(b) preparing an oxidation reaction educt mixture MOE from the at least a part of the stream SBI, preferably the stream SBIL, and the stream Sox, and subjecting the mixture MOE to oxidation reaction conditions, obtaining an oxidation reaction product stream SOP comprising E-caprolactam, further comprising one or more oxidation reaction products ZP obtained from the oxidation of at least a part of the one or more compounds Z, and optionally further comprising a part of the one or more organic compounds Z;(c) passing the stream SOP, preferably after further treatment, as chemically treated part of the stream SBI , preferably as chemically treated stream SBIL, to separating the one or more compounds X according to (ill).Preferably, the at least one permanganate comprised in the stream Sox provided according to (a) comprises, preferably consists of, at least alkali metal permanganate, wherein more preferably, the at least one alkali metal permanganate comprises one or more of sodium permanganate and potassium permanganate. Preferably from 0.5 to 100 weight-% of the stream Sox provided according to (a) consist of permanganate. More preferably, the stream Sox provided according to (a) and the mixture MOE prepared according to (b) further comprise water.Preferably, the oxidation reaction educt mixture MOE prepared according to (b) exhibits a permanganate concentration, calculated as MnC , in the range of from 0.005 to 5 weight-%, preferably in the range of from 0.01 to 3 weight- %, more preferably in the range of from 0.05 to 1 weight-%.Preferably, subjecting the mixture MOE to oxidation reaction conditions is carried out in an oxidation reaction section UOR, wherein the reaction section UOR preferably comprises one or more of a stirred tank reactor, a dynamic mixer, a tube reactor, a static mixer, and an exit tube of said static mixer.The oxidation reactions conditions according to (b) comprise an oxidation reaction time AtoE in the range of from 5 min to 8 h and a temperature TOE in the range of from 20 to 140 °C, wherein if TOE is in the range of from 20 to 40 °C, AtoE is preferably in the range of from 2 to 8 h; if TOE is in the range of from 60 to 90 °C, AtoE is preferably in the range of from 15 to 45 min; if TOE is in the range of from 100 to 140 °C, AtoE is preferably in the range of from 5 to 15 min.According to the present invention, especially preferably if the temperature TOE is in the range of from 100 to 140 °C, the reaction section UOR as defined herein comprises, optionally consists of, a static mixer and an exit tube of said static mixer. Thus, it may by possible that for the chemical treatment, no stirred reactor is necessary because AtoE is so short that the oxidation reaction takes place already in the statix mixer and in the exit tube thereof.The further treatment according to (c) preferably comprises subjecting the stream SOP to a solid-liquid separation stage, preferably comprising one or more of a filtration stage and a centrifugation stage, more preferably a filtration stage. More preferably, in this solid-liquid separation separation stage, MnC>2 and fines, if present, are separated.Further in the context of the chemical treatment of the present invention, it is preferred that the process further comprises providing a stream SOB comprising at least one hydroxide, wherein the at least one hydroxide comprised in the stream SOB preferably comprises, more preferably consists of, at least alkali metal hydroxide, wherein more preferably, the at least one alkali metal hydroxide comprises, more preferably consists of, sodium hydroxide. Preferably from 0.5 to 100 weight-% of the stream SOB consist of hydroxide, wherein more preferably, the stream SB further comprises water.Preferably, the stream SOB is passed into the process upstream of the chemical treatment stage, preferably into the distillation column Di, more preferably into the top of the distillation column Di; and / or during the chemical treatment stage, preferably either as a component for preparing the oxidation reaction educt mixture MOE according to (b); and / oradmixing with the stream SOP, either upstream of and / or downstream of the solid-liquid separation as defined herein; and / or downstream of the chemical treatment stage and upstream of separating the one or more compounds X according to (ill).Preferably, the chemical treatment stage further comprises, at any point downstream of (ii) and upstream of (ill), an adsorption stage, wherein the respectively used adsorption agent preferably comprises charcoal, more preferably activated charcoal, wherein more preferably, said adsorption agent is arranged as a fixed adsorption bed. According to a preferred process, the adsorption stage is arranged upstream of preparing the oxidation reaction educt mixture MOE according to (b) as described herein.Therefore, the apparatuses used in the chemical treatment stage of the present invention preferably comprise(A) at least one mixing device for preparing the oxidation reaction educt mixture MOE as defined herein;(B) at least one oxidation reaction section UOR for subjecting the mixture MOE to oxidation reaction conditions as defined herein;(C) at least one a solid-liquid separation section for subjecting the stream SOP to solid-liquid separation as defined herein;(D) preferably at least one mixing device for admixing a stream SOB comprising at least one hydroxide as defined herein;(E) optionally an adsorption device as defined herein.Preferably at least the apparatuses according to (A), (B), (C) and (D) are vertically arranged relative to each other.Providing SoPreferably according to the present invention, providing the aqueous stream So comprising E-caprolactam according to (I) comprises(1.1) providing a stream SM comprising a solid material M comprising polyamide 6;(1.2) preparing an aqueous depolymerization mixture MDI from SM;(1.3) subjecting the mixture MDI to a first depolymerization and purification stage, comprising(1.3.1) subjecting the mixture MDI in a depolymerization unit URI to polyamide 6 depolymerization conditions DRI comprising a depolymerization temperature TRI at a depolymerization pressure PRI, obtaining a liquid aqueous product stream SRI comprising monomeric E-caprolactam at a concentration CRI (C), polyamide 6 at a concentration CRI (P), one or more compounds X and one or more compounds Y;(1.3.2) passing the liquid aqueous stream SRI into a first water separation unit Uwsi, obtaining from SRI a liquid aqueous product stream Swsi comprising monomeric E-caprolactam at a concentrationCwsi(C) > CRI(C), polyamide 6 at a concentration Cwsi(P) > CRI (P), one or more compounds X and one or more compounds Y, and further obtaining at least one aqueous residue stream SR.WSI comprising separated water;(i .3.3) passing the liquid aqueous stream Swsi into a high boiler separation unit UHSI, obtaining from Swsi an aqueous product stream SP-HSI comprising monomeric E-caprolactam at a concentration cp. HSI(C) > Cwsi(C), one or more compounds X at a total concentration CP-HSI(X) < cwsi(X)and one or more compounds Y, and further obtaining from Swsi an aqueous residue stream SR.HSI comprising polyamide 6 at a concentration CR.HSI(P) > Cwsi(P), one or more compounds X at a total concentration CR.HSI(X) > Cwsi(X) and optionally, in a residual amount, one or more compounds Y;(1.4) preferably passing the aqueous residue stream SR.HSI to further treatment, comprising(1.4.1) recycling at least a part of the stream SR.HSI to (ill), comprising subjecting the at least part of the stream SR.HSI in the depolymerization unit URI to the polyamide 6 depolymerization conditions DRI; and / or(1.4.2) subjecting at least a part of the stream SR.HSI to a second depolymerization and purification stage, comprising(1.4.2.1) subjecting the at least part of the stream SR.HSI in a depolymerization unit UR2 to polyamide 6 depolymerization conditions DR2 comprising a depolymerization temperature TR2 at a depolymerization pressure pR2, obtaining a liquid aqueous stream SR2 comprising monomeric E-capro-lactam at a concentration CR2(C), optionally polyamide 6 at a concentration CR2(P) < CR.HSI (P), and optionally one or more compounds Y;(1.4.2.2) passing the liquid aqueous stream SR2 into a second water separation unit Uws2, obtaining from SR2 a liquid aqueous product stream Sws2 comprising monomeric E-caprolactam at a concentration cws2(C) > CR2(C), polyamide 6 at a concentration cws2(P) > CR2(P), one or more compounds X and optionally one or more compounds Y, and further obtaining at least one aqueous residue stream SR.WS2 comprising separated water;(1.4.2.3) passing the liquid aqueous stream Sws2 into a high boiler separation unit UHS2, obtaining from Sws2 an aqueous product stream SP-HS2 comprising monomeric E-caprolactam at a concentration CP-HS2(C) > cws2(C), optionally one or more compounds X and optionally one or more compounds Y, and further obtaining from Sws2 an aqueous residue stream SR-HS2 comprising one or more compounds X at a total concentration CR.HS2(X) > cws2(X), optionally polyamide 6 at a concentration CR.HS2(P) > cws2(P) and optionally one or more compounds Y;(1.4.2.4) passing the aqueous residue stream SR.HS2 to further treatment, comprising(1.4.2.4.1) recycling at least a part of the stream SR.HS2 to (i.4.2.1), comprising subjecting the at least part of the stream SR.HS2 in the depolymerization unit Up2to the polyamide 6 depolymerization conditions DR2; and / or(1.4.2.4.2) passing at least a part of the stream SR.HS2 to a further use;(i.5) passing the aqueous product stream SP-HSI obtained according to (i.3.1), comprising monomeric E-caprolac- tam at the concentration CP-HSI(C), one or more compounds X, and one or more compounds Y and water at a concentration CP-HSI(W); and preferably the aqueous product stream SP-HS2 obtained according to (i.4.2.3), comprising monomeric E-caprolactam at the concentration CP-HS2(C), optionally one or more compounds X, optionally one or more compounds Y, and water at a concentration CP-HS2(W) to a third water separation unit Uws3, obtaining the aqueous stream So comprising E-caprolactam at a concentration Cso(C), one or more organic compounds X at a total concentration cso(X), one or more organic compounds Y at a total concentration cso(Y), and water at a concentration Cso(W).According to (1.1), the solid material M comprised in the stream SM especially preferably comprises, more preferably consists of, a waste material, wherein said waste material more preferably comprises, more preferably consists of, one or more of at least one textile waste material and at least one engineering plastics waste material, more preferably comprises, more preferably consists of at least one textile waste material.Preferably from 10 to 99 weight-%, more preferably from 30 to 98.5 weight-%, more preferably from 50 to 98 weight- %, more preferably from 80 to 98 weight-% of the solid material M consist of polyamide 6.In addition to polyamide 6, the solid material M preferably comprises one or more further organic polymeric compounds, more preferably including, but not limited to, one or more of at least one elastane; at least one polyamide 6.6; at least one semiaromatic polyamide including one or more of polyamide 6T and polyamide 6I; at least one polyethylene terephthalate; at least one polyurethane; at least one polyester; at least one polyether; at least one polyvinyl chloride; at least one natural fiber material such as wool and cotton; at least one cellulose material; at least one natural elastomer; at least one synthetic elastomer; at least one copolymer of two or more of said polymeric compounds including statistical copolymers, gradient copolymers, alternating copolymers, block copolymers, and graft copolymers; and at least one rubber material comprising one or more of at least one natural rubber material and at least one synthetic rubber material.Prior to being provided to the process of the present invention, the waste material can be suitably sorted. In this regard, it is possible to spread the collected textile waste material on a conveyor, which spreading can be carried out either manually and / or mechanically. Thereafter, the respectively spread textile waste material is subjected to sorting, either by composition and / or by color. Sorting can be carried out either manually and / or optically. If carried out optically, the sorting preferably comprises an infrared sorting, more preferably a near-infrared sorting and / or a mid-infra- red sorting. Optionally, prior to sorting, the textile waste material can be subjected to a suitable metal removing step. If a metal removing step is carried out, ferrous elements are preferably separated, for example by suitable magnetic means, and / or non-ferrous elements are preferably separated, for example by suitable eddy current separating means. After said sorting, the respectively obtained textile waste material can be subjected to a further treatment, such as cutting and / or milling.Generally, the solid material M can be provided according to any suitable method. Preferably according to the present invention, providing the solid material M comprises providing the solid material M in a delivering unit which preferably comprises one or more of at least one big bag station and at least one a bulk container station; passing the provided solid material M via a first connecting line from the delivering unit to a material collecting unit, preferably a collecting drum, wherein the first connecting line preferably comprises one or more of at least one material receiving and discharge unit, at least one first material feeding unit, and at least one first particle separation unit; passing the solid material M from the material collecting unit via a second connecting line to a melting unit UM as described herein, wherein the second connecting line preferably comprises one or more of at least one second material feeding unit, at least one second particle separation unit, and at least one metal detector.Optionally of preferably, the solid material M may be provided in the form of granules, wherein the particle size distribution of said granules is preferably characterized by one or more of the following pairs of values, preferably by two or more of the following pairs of values, more preferably by the following three pairs of values: a D10 value of the particle width in the range of from in the range of from 0.1 to 15 mm and a D10 value of the particle length in the range of from 0.3 to 15 mm; a D50 value of the particle width in the range of from in the range of from 0.2 to 20 mm and a D50 value of the particle length in the range of from 0.5 to 20 mm; a D90 value of the particle width in the range of from in the range of from 0.3 to 30 mm and a D90 value of the particle length in the range of from 0.8 to 30 mm.According to (i .2), the aqueous depolymerization mixture is prepared. While there are no specific restrictions in this regard, it is preferred that preparing the aqueous depolymerization mixture MDI comprises melting in a melting unit UM the solid material M comprised in the stream SM having a temperature TSM at a pressure PSM, obtaining a liquid stream SM; admixing in a pre-reaction unit UPR the liquid stream SM with an aqueous stream Sw having a temperature Tsw at a pressure psw, obtaining the depolymerization mixture MDI having a temperature TMDI at a pressure PMDI.The pre-reaction unit UPR preferably comprises, more preferably consists of, a mixing unit, preferably a static mixing unit, and wherein the melting unit UM comprises, preferably consists of an extruder, preferably a single-screw extruder or a twin-screw extruder. Further, it is preferred that Sw and SM are admixed in UPR at a mixing ratio (mw / kg) I (mp / kg) in the range of from 1 :1 to 20:1, more preferably in the range of from 2:1 to 15:1, more preferably in the range of from 5:1 to 10:1, wherein mw is the amount of water comprised in Sw and mp is the amount of polyamide 6 comprised in SM.Preferably according to the process of the present invention, the polyamide 6 depolymerization conditions DRI according to (i.3.1) comprise a depolymerization pressure PRI in the range of from 40 to 140 bar, more preferably in therange of from 40 to 125 bar, more preferably in the range of from 40 to 110 bar; and a depolymerization temperature TRI in the range of from 230 to 335 °C, preferably in the range of from 250 to 320 °C, more preferably in the range of from 270 to 310 °C.As far as this process design is concerned, it is preferred that0.8 s TMDI / TRI 1.05 and 0.9 s PMDI / PRI - 1.05;0.6 < TSM / TMDI 1.2 and 0.9 < PSM / PMDI 1.05; and0.8 s TSW / TMDI - 1.2 and 0.9 s psw / pivoi - 1 .05.Preferably, the depolymerization unit URI comprises z chemical reactors Rn, i=1 ...zi, wherein zi is in the range of from 1 to 10, preferably in the range of from 1 to 8, more preferably in the range of from 1 to 6, more preferably in the range of from 1 to 5, more preferably in the range of from 1 to 4, more preferably in the range of from 1 to 3. If zi > 1, is preferred that at least 2 reactors Rn, more preferably all zi reactors Rn, are serially coupled, wherein the depolymerization mixture MDI is fed into Rn, with i = 1 ; an aqueous liquid stream Sn containing E-caprolactam dissolved in water is removed from reactor Rn and fed into the reactor Ri(i+i>, with i < zi; an aqueous liquid stream Sizcontaining E-caprolactam dissolved in water is removed from the reactor Rizias the stream SRI; wherein in every reactor Rn, a depolymerization temperature TRU at a depolymerization pressure PRU is maintained, wherein, independently of each other, TRU is in the range of from 230 to 330 °C and PRU is in the range of from 40 to 140 bar, preferably wherein TRU is in the range of from 250 to 320 °C and PRU is in the range of from 40 to 125 bar, more preferably wherein TRU is in the range of from 270 to 310 °C and PRU is in the range of from 40 to 110 bar. For zi > 1 , it is preferred that the zi reactors Rn are vertically arranged, with Rn being the top-most reactor and Rizibeing the bottom-most reactor, wherein Sn obtained from Rn is transferred to Ri(i+i> by gravity, preferably by gravity only. More preferably, at least 1 , preferably all zi reactors Rn, are continuous stirred tank reactors (CSTR). Preferably, every continuous stirred tank reactor Rn has, independently from each other, from 2 to 6 compartments, more preferably from 2 to 5 compartments, more preferably from 2 to 4 compartments, said compartments preferably being serially, more preferably being serially and vertically arranged, wherein 2 adjacent compartments are separated by a divider which comprises at least one flow-through opening. Preferably at least one compartment comprised in a reactor Rii comprises at least one agitator, wherein more preferably every compartment of every reactor Rn comprises at least one agitator, wherein more preferably, every compartment of every reactor Rn comprises one agitator, and the process comprises agitating the depolymerization mixture in a given compartment for at least part of the time during subjecting to depolymerization conditions in said compartment. Preferably, the polyamide 6 depolymerization conditions further comprise a total residence time IRI of the aqueous depolymerization mixture in the unit URI, preferably in the zi reactors Rn, more preferably in the zi continuous stirred tank reactors, wherein at least 85 weight-%, preferably at least 90 weight-%, more preferably at least 95 weight-% of the aqueous depolymerization mixture have a IRI inthe range of from 30 to 90 min. More preferably, the residence time of an aqueous depolymerization mixture in a reactor Rii is tRii and 0.90 < (IRH I tRi(i+i>) < 1.10, more preferably 0.95 < (IRH I tRi(i+i>) < 1.05.Preferably according to the present invention, no polyamide 6 depolymerization catalyst such as a mineral acid and / or a zinc salt such as zinc chloride, zinc acetate or zinc triflate is used for preparing the depolymerization mixture MDI, is contained in the depolymerization mixture MDI to be subjected to depolymerization conditions in URI, and is present during depolymerization in URI.Preferably, the liquid aqueous stream SRI according to (i.3.1) has a temperature in the range of from 230 to 330 °C, preferably in the range of from 250 to 320 °C, more preferably in the range of from 270 to 310 °C. Further preferably, in the liquid aqueous stream SRI according to (i.3.1), the weight ratio of water relative to the sum of monomeric E- caprolactam, polyamide 6 and the at least one compound X, m(W) / (m(C)+(m(P)+(X)), is in the range of from 5:1 to 15:1, preferably in the range of from 6:1 to 10:1, more preferably in the range of from 7:1 to 9:1. Preferably from 98 to 100 weight-%, more preferably from 99 to 100 weight-%, more preferably from 99.5 to 100 weight-%, more preferably from 99.9 to 100 weight-% of the stream SRI consist of monomeric E-caprolactam, polyamide 6, the one or more compounds X, one or more compounds Y and water.According to the present invention, the term ..polyamide 6" which is comprised in the stream SR.HSI encompasses polymeric polyamide 6 as well as any oligomeric polyamide 6. Said oligomeric polyamide 6 can be comprised already in the depolymerization mixture MDI subjected to depolymerization conditions according to (i.3.1), and generally, is formed from polyamide 6 in the first depolymerization stage carried out according to (I3..1). Further, it may be possible that some oligomeric polyamide 6 is formed during the first water separation stage according to (1.3.2). Further, the term "oligomeric polyamide 6” encompasses any oligomers starting from dimers and, therefore, includes E-capro- lactam dimer, E-caprolactam trimer, E-caprolactam tetramer, E-caprolactam pentamer, E-caprolactam hexamer, and so forth, wherein the oligomers may exhibit a linear and / or a cyclic structure.The liquid aqueous stream Swsi according to (1.3.2) has a temperature preferably in the range of from 75 to 120 °C, more preferably in the range of from 80 to 110 °C, more preferably in the range of from 85 to 100 °C. In the liquid aqueous stream Swsi, the weight ratio of water relative to the sum of monomeric E-caprolactam, polyamide 6 and the at least one compound X, m(W) / (m(C)+(m(P)+(X)), is preferably in the range of from 0.13:1 to 0.4:1, more preferably in the range of from 0.14:1 to 0.3:1, more preferably in the range of from 0.15:1 to 0.2:1. Preferably from 98 to 100 weight-%, more preferably from 99 to 100 weight-%, more preferably from 99.5 to 100 weight-%, more preferably from 99.9 to 100 weight-% of the stream Swsi consist of monomeric E-caprolactam, polyamide 6, the one or more compounds X, one or more compounds Y and water.According to a first alternative with regard to (1.3.3), it is preferred that the high boiler separation unit UHSI according to (1.3.3) is an evaporation unit, (1.3.3) comprising(1.3.3.1) passing the stream Swsi into the unit UHSI, preparing in the unit UHSI from the stream Swsi an evaporation mixture MHSI having an evaporation temperature THSI at an evaporation pressure PHSI with THSI > Twsi, wherein the one or more one organic compounds X have a boiling point TBX and monomeric E- caprolactam has a boiling point TBC with TBX > THSI TBC at the evaporation pressure PHSI;(1.3.3.2) removing the stream SP-HSI from the unit UHSI, the stream SP-HSI having a temperature TP-HSI with TP-HSITHSI;(1.3.3.3) removing the stream SR.HSI from the unit UHSI, the stream SR.HSI having a temperature TR.HSI with TR.HSI = Tp-HS1.In the context of said first alternative, PHS 1 is preferably in the range of from 50 to 200 mbar and T HSI is preferably in the range of from 220 to 330 °C, more preferably in the range of from 240 to 320 °C, more preferably in the range of from 260 to 310 °C; wherein preparing the mixture MHSI in the unit UHSI according to (1.3.3.1) more preferably comprises heating the stream Swsi passed into the unit UHSI from the temperature Twsi to the evaporation temperature THSI via internal heating means HINTI arranged within the unit UHSI, thereby obtaining the evaporation mixture MHSI; or passing, in addition to the stream Swsi, a stream Sxi into the unit UHSI, the stream Sxi having a temperature Txi > Twsi, admixing the stream Sxi and the stream Swsi and heating the obtained mixture to the temperature THSI via internal heating means HINTI arranged within the unit UHSI, thereby obtaining the evaporation mixture MHSI, wherein the process further separating the stream Sxi from the stream SR.HSI, wherein the stream Sxi has the temperature Tx = TR.HSI; or passing, in addition to the stream Swsi, a stream SYI into the unit UHSI, the stream SYI having a temperature TYI > THSI, and admixing the stream Swsi and the stream Syi, thereby obtaining the evaporation mixture MHSI, wherein the process further comprises separating a stream Sxi from the stream SR.HSI, wherein the stream Sxi has a temperature Txi = THSRI; and subjecting the stream Sxi to heating via external heating means HEXTI arranged outside the unit UHSI, obtaining the stream SYI having the temperature Tyi; and wherein preferably Tyi > (THSI + 10 K), more preferably TYI > (THSI + 20 K), more preferably TYI > (THSI + 30 K).Further in the context of said first alternative, the process preferably further comprises subjecting the stream SP-HSI to cooling in a cooling unit, obtaining from said cooling unit a cooled stream SR-HSI, more preferably obtaining a cooled and partially condensed stream SR-HSI, and wherein the cooled stream SP-HSI has a temperature TP-HSI preferably in the range of from 160 to 320 °C, more preferably in the range of from 165 to 310 °C, more preferably in the range of from 170 to 300 °C.With regard to said first alternative, it is preferred that the water separation unit Uws3 as defined herein comprises two or more water separation sub-units, more preferably two water separation sub-units UWSSA and UWSSB, more preferably two serially coupled water separation sub-units UWSSA and UWSSB with UWSSB being arranged upstream of Uws2. Preferably, the water separation sub-unit UWSSA comprises, more preferably consists of, a droplet separator, more preferably selected from the group consisting of a hydrocyclone, a demister plate, and an absorption tower, more preferably a hydrocyclone; and the water separation sub-unit UWSSB preferably comprises, more preferably consists of, a distillation column.According to a second alternative with regard to (1.3.3), it is preferred that the high boiler separation unit UHSI according to (1.3.3) is a stripping unit, (1.3.3) comprising(1.3.3.1) passing the stream Swsi and an aqueous stripping gas stream SGOI into the unit UHSI, wherein the aqueous stripping gas stream SGOI has a temperature TGOI with TGOI > Twsi;(1.3.3.2) bringing the stream Swsi and the stream SGOI in the unit UHSI at stripping conditions into contact with each other, wherein the stripping conditions comprise a stripping pressure PHSI and wherein at the stripping pressure PHSI, the one or more one organic compounds X comprised in the stream Swsi have a boiling point TBX and monomeric E-caprolactam has a boiling point TBC < TBX;(1.3.3.3) removing the stream SP-HSI from the unit UHSI, the stream SP-HSI having a temperature TP-HSI with Twsi< Tp-HS1 < TGOI;(1.3.3.4) removing the stream SR.HSI from the unit UHSI, the stream SR.HSI having a temperature TP-HSI with Twsi< TR-HSI < TGOI •In the context of said second alternative, it is preferred that from 95 to 100 weight-%, more preferably from 98 to 100 weight-%, more preferably from 99 to 100 weight-%, more preferably from 99.5 to 100 weight-%, more preferably from 99.8 to 100 weight-%, more preferably from 99.9 to 100 weight-% of the aqueous stripping gas stream SGOI consist of water; and that TGOI is preferably at least 250 °C, more preferably in the range of from 250 to 500 °C, more preferably in the range of from 300 to 450 °C.With regard to said second alternative, it is preferred that the water separation unit Uws3 as defined herein comprises two or more water separation sub-units, more preferably two water separation sub-units UWSSA and UWSSB, more preferably two serially coupled water separation sub-units UWSSA and UWSSB with UWSSA being arranged upstream of UWSSB. Preferably, the water separation sub-unit UWSSA comprises, preferably consists of, a scrubbing unit, and wherein the water separation sub-unit UWSSB comprises, preferably consists of, a distillation column.According to a third alternative with regard to (1.3.3), it is preferred that the high boiler separation unit UHSI according to (1.3.3) is a stripping unit, (1.3.3) comprising(1.3.3.1) passing the stream Swsi and a non-aqueous stripping gas stream SGOI into the unit UHSI, wherein the non-aqueous stripping gas stream SGOI comprises at least one inert gas G1 and has a temperature TGOI with TGOI > Twsi;(1.3.3.2) bringing the stream Swsi and the stream SGOI in the unit UHSI at stripping conditions into contact with each other, wherein the stripping conditions comprise a stripping pressure PHSI and wherein at the stripping pressure PSHSI, the one or more one organic compounds X comprised in the stream Swsi have a boiling point TBX and mo-nomeric E-caprolactam has a boiling point TBC < TBX;(1.3.3.3) removing the stream SP-HSI from the unit UHSI, the stream SP-HSI having a temperature TP-HSI with Twsi< Tp-HS1 < TGOI;(1.3.3.4) removing the stream SR.HSI from the unit UHSI, the stream SR.HSI having a temperature TR.HSI with Twsu< TR.HSI < TGOI,In the context of said third alternative, it is preferred that the at least one inert gas G1 comprises one or more of nitrogen and carbon dioxide, more preferably nitrogen, wherein more preferably, at least 99 weight-%, more preferably at least 99.5 weight-%, more preferably at least 99.9 volume -% of the at least one inter gas G1 consist of nitrogen, wherein more preferably from 95 to 100 weight-%, more preferably from 99 to 100 weight-%, more preferably from 99.9 to 100 weight-% of the non-aqueous stripping gas stream SGOI consist of the at least one inert gas G1 ; and wherein TGOI is at least 250 °C, preferably in the range of from 250 to 500 °C, more preferably in the range of from 300 to 450 °C.With regard to said second alternative, it is preferred that the water separation unit Uws3 as defined herein comprises, more preferably consists of, a distillation column.With regard to the setup of the second depolymerization and purification stage according to (i.4.2), no specific limitations exist. Generally, it may be preferred to use the same or essentially the same apparatus setup as in the first depolymerization and purification stage according to (1.3).Recycling of streamsRegarding the preferred way of providing the stream So described herein, it is further preferred that the process of the present invention further comprises recycling at least a part of the stream STI obtained at the top of the first distillation column to (1.2) as part of the aqueous depolymerization mixture MDI; and / or to (i.4.2) as part of the at least a part of the stream SR.HSI to be subjected to a second depolymerization and purification stage according to (i.4.2.1).Further regarding the preferred way of providing the stream So described herein, it is further preferred that the process of the present invention further comprises recycling at least a part of the stream SB2 obtained at the bottom ofthe second distillation column to the high boiler separation unit UHSI according to (i.3.3) and / or the high boiler separation unit UHS2 according to (i.4.2.3).Further regarding the process of the present invention, it may be preferred to recycle at least a part of the stream STS obtained at the top of the third distillation column.CrystallizationAs mentioned above, the process of present invention may include, as a preferred downstream stage, a suitable crystallization stage. If this crystallization is realized, it is preferred that the process of the present invention further comprises(v.1) passing at least a part of the stream SB3 obtained at the bottom of the distillation column D3 to a downstream treatment stage comprising a crystallization; and / or(v.3) passing at least a part of the stream Ss2 obtained at the side of the distillation column D2 to a downstream treatment stage comprising a crystallization; obtaining from said crystallization an E-caprolactam product stream SPF.Preferably, the crystallization may be carried out in a crystallization unit U comprising(1) h crystallization sub-units Uc(H), H = 1 ...h and h > 2, wherein each crystallization sub-unit UC<H) comprises s crystallizer WC(S(H», S(H) = 1...S and s > 1; a stream transportation line LC(H) passing through the s crystallizer WC(S(H», comprising an entry and exit point EC(H) connected to the stream distribution sub-unit UD according to (3) and further comprising controllable means MEC(HJ for passing a stream from UD into LC<H) and for passing a stream from LC(H) to UD;(2) a batch drum sub-unit UB comprising k batch drums B(i) with I = 1 ...k and k > 2, wherein each batch drum B(i) is equipped with controllable means MB(I) for passing a stream from B(i) via the stream distribution sub-unit UD according to (3) to at least one of EC(H>; a crude E-caprolactam feed stream transportation line Lso to at least one batch drum B(i);(3) a stream distribution sub-unit UD connecting UB and the h sub-units UC<H), the sub-unit UD comprising(3.1) for each drum B(i) with i = 1...k(3.1.1) at least one of a stage stream transportation line Ls<Hi)(i) from B(i) to at least one EC<HI) and a stage stream transportation line Ls<H2)(i) from B(i) to at least one EC<H2), H1 + H2, wherein Ls<Hi)(i) comprises at least one controllable means MLS<HI)(I) for passing a stream from B(i) to Ec(W) and l_s<H2)(i) comprises at least one controllable means MLS<H2)(I) for passing a stream from B(i) to Ec(H2>;(3.1 .2) at least one of a back stream transportation line LB<H IJ(I) from EC<HI) to B(i) and a back stream transportation line LB(H2)0) from EC<H2) to B(i), wherein LB(HI)O) comprises at least one controllable means MLB<HI)(I) for passing a stream from EC<HI) to B(i) and LB<H2)(I) comprises at least one controllable means MLB<H2)(I) for passing a stream from Ec(H2) to B(i);(3.2) a final residue stream transportation line LR<H3) , H3 + H1 ,H2, for removing a final crystallization residue stream SRF from a transportation line LC(H) via EC<H), wherein LR<H3) comprises at least one controllable means MLR<H3) for removing said final residue stream SRF from LC(H>;(3.3) a final fine product stream transportation line LF(H4), H4 + H1 ,H2,H3, for removing a final fine crystallization product stream SPF from a transportation line LC(H) via EC<H), wherein LF<H4) comprises at least one controllable means MLF<H4) for removing said final fine product stream SPF from LC(H>; the process comprising(I) passing the at least a part of the stream STS and / or the at least a part of the stream Ss2 into a batch drum B(i), 1 < i < k;(II) subjecting the content of the batch drum B(i) to crystallization comprising n crystallization stages P(x) carried out in at least one sub-unit Uc(H2> with 1 < n < (k-i+1) and x = 1 ...n, and further comprising m crystallization stages C(y) carried out in at least one sub-unit Uc(Hi) with 0 < m < (i-1) and y = 1...m for m > 0, wherein H1 + H2;(11.1) wherein a crystallization stage P(x) comprises(11.1.1) passing a stage stream Ss(x+i-1) comprising at least a part of the content of a batch drum B(x+i-1 ) from said batch drum B(x+i-1 ) via the transportation line Ls<H2)(x+i-1 ) and the entry and exit point EC<H2) into the transportation line LC(H2>;(11.1.2) passing the stream Ss(x+i-1) through the transportation line LC<H2) with the means MC<H2), thereby passing through the at least one crystallizer Wc(s(H2», wherein in Wc(s(H2», E-capro- lactam comprised in Ss(x+i-1 ) crystallizes and remains as crystallized solid in Wc(s(H2»;(11.1.3) removing a residue stream SR(X-H-1) from the transportation line Lc(H2) via EC<H2), wherein the stream SR(X-H-1 ) is depleted in E-caprolactam compared to the stream Ss(x+i-1 ); and(1.3.1) passing the stream SR(X-H-1) via the transportation line LR<H3) as final residue stream SRF via MLR(H3> to optional further use; or(1 .3.2) passing the stream SR(X-H-1 ) via the transportation line LB(H2)(X-H-2) into the batch drum B(x+i-2);(11.1.4) transferring the crystallized solid in Wc(s(H2» into a liquid product stream Sp(x+i-1);(11.1.5) removing the stream Sp(x+i-1) from the transportation line LC<H2) via EC<H2), wherein the stream Sp(x+i-1 ) is concentrated in E-caprolactam compared to the stream Ss(x+i-1 ), and(1.5.1) passing the stream Sp(x+i-1) via the transportation line LF<H4) as final E-caprolac- tam fine product stream SPF via MLF<H4) to further use; or(1 .5.2) passing the stream Sp(x+i-1) via the transportation line LB(H2)(X-H) into the batch drum B(x+i);(II.2) wherein a crystallization stage C(y) comprises(11.2.1) passing a stage stream Ss(i-y) comprising at least a part of the content of a batch drum B(i- y) from said batch drum B(i-y) via the transportation line Ls<Hi)(i-y) and the entry and exit point EC(HIJ into the transportation line LC(HI>;(11.2.2) passing the stream Ss(i-y) through the transportation line LC(HI) with the means MC<HI), thereby passing through the at least one crystallizer WC(S(HI», wherein in WC(S(HI», E-capro- lactam comprised in Ss(i-y) crystallizes and remains as crystallized solid in WC(S(HI»;(11.2.3) removing a residue stream SR(i-y) from the transportation line LC(HI), wherein the stream SR(i-y) is depleted in E-caprolactam compared to the stream Ss(i-y); and(2.3.1) passing the stream SR(i-y) via the transportation line LR<H3> as final residue stream SRF via MLR(H3> to optional further use; or(2.3.2) passing the stream SR(i-y) via the transportation line LB<Hi)(i-y-1 ) into the batch drum B(i-y-1);(11.2.4) transferring the crystallized solid in WC(S(HI» into a liquid product stream Sp(i-y);(11.1.5) removing the stream Sp(i-y) from the transportation line LC(HI> via EC<HI), wherein the stream Sp(i-y) is concentrated in E-caprolactam compared to the stream Ss(i-y), and passing the stream Sp(i-y) via the transportation line Ls<Hi)(i-y+1 ) into the batch drum B(i-y+1 ).The process of the present invention may further comprise a downstream polymerization stage in which the ultimate product stream comprising monomeric E-caprolactam obtained from the stages as defined above is subjected to suitable polyamide 6 polymerization conditions.If such polymerization stage is realized, it is preferred that the process further comprises(a) passing the stream Ss2 and / or the stream SB3, preferably the stream SPF according to (11.1.5.1) as defined in embodiment 54, to a polyamide 6 production plant UPAG;(|3) subjecting the stream Ss2 and / or the stream SB3, preferably the stream SPF, to E-caprolactam polymerization conditions, obtaining from UPA6 a polyamide 6 material MP and a stream comprising water and one or more E- caprolactam oligomers;(y) optionally subjecting to stream comprising water and one or more E-caprolactam oligomers to concentration with respect to the one or more E-caprolactam oligomers in at least one concentration stage, obtaining a concentrated stream comprising water and one or more E-caprolactam oligomers;(5) passing the optionally concentrated stream comprising water and one or more E-caprolactam oligomers into at least one of the melting unit UM as defined herein and the water separation unit Uwsi as defined herein.Preferably, the optionally concentrated stream comprising water and one or more E-caprolactam oligomers according to (5) further comprises monomeric E-caprolactam. Further preferably, said integrated process comprises (p) subjecting the stream Ss2 and / or the stream SB3, preferably the stream SPF, in UPA6 toE-caprolactam polymerization conditions, obtaining from UPA6 a polyamide 6 material MP and a stream SEW comprising water at a concentration CEW(W), monomeric E-caprolactam at a concentration CEW(C), and one or more E-caprolactam oligomers at a total concentration CEW(O);(y) subjecting the stream SEW to concentration, comprising(y.1 ) subjecting the stream SEW to concentration in a first concentration unit Uci, obtaining from Uci a concentrated stream Sci comprising water at a concentration Cci(W), monomeric E-caprolactam at a concentration cci (C), and one or more E-caprolactam oligomers at a total concentration cci (0), with Cci(W) < CEW(W), CCI (C) > CEW(C) and Cci(O) > CEW(0), and further obtaining from Uci an aqueous stream Swi comprising water at a concentration Cwi(W) > CEW(W);(y.2) subjecting the stream Sci to concentration in a second concentration unit Uc2, obtaining from Uc2 a concentrated stream Sc2 comprising one or more E-caprolactam oligomers at a total concentration cc2(0), with cc2(0) > cci(0), and further obtaining from Uc2 an aqueous stream Sw2 comprising water at a concentration cw2(W) and monomeric E-caprolactam at a concentration Cw2(C), with cw2(W) > Cwi(W) and cw2(C) > cwi(C);(5) passing the stream Sc2 to the sub-unit UM and the stream Sw2 to the separation unit Uwsi.As described above, the stream SEW which is obtained from the polyamide 6 polymerization plant UPA6 comprises water, monomeric E-caprolactam and one or more E-caprolactam oligomers. Usually, this aqueous stream SEW further comprises one or more further organic compounds other than monomeric E-caprolactam and one or more E-caprolac- tam oligomers. Therefore, it is preferred that the stream SEW further comprises one or more organic compounds V other than monomeric E-caprolactam and oligomers thereof at a total concentration CEW(V), the process according to (y) comprising(y.1 ) subjecting the stream SEW to concentration in a first concentration unit Uci, obtaining from Uci a concentrated stream Sci comprising water at a concentration Cci(W), monomeric E-caprolactam at a concentration cci (C), one or more E-caprolactam oligomers at a total concentration Cci(O) and one or more organic compounds V at a total concentration cci (V), with Cci(W) < CEW(W), CCI (C) > CEW(C), CCI(O) > CEW(0) and cci(V) > CEW(V), and further obtaining from Uci an aqueous stream Swi comprising water at a concentration Cwi(W) > CEW(W);(y.2) subjecting the stream Sci to concentration in a second concentration unit Uc2, obtaining from Uc2 a concentrated stream Sc2 comprising one or more E-caprolactam oligomers at a total concentration cc2(0) and one or more organic compounds V at a total concentration Cc2(V), with cc2(0) > Cci(O) and cc2(V) > cci (V), and further obtaining from Uc2 an aqueous stream Sw2 comprising water at a concentration cw2(W) and monomeric E- caprolactam at a concentration Cw2(C), with cw2(W) > Cwi(W) and cw2(C) > Cwi(C).More preferably according to the present invention, (p) comprises(p.1 ) passing the stream Ss2 and / or the stream SB3, preferably the stream SPF, and preferably an aqueous stream SAQO to a polymerization stage STo, obtaining from STo a polyamide 6 crude product stream SPAI and an aqueous stream SWAI;(p.2) passing the stream SPAI and preferably an aqueous stream SAQI to a granulation stage ST 1, obtaining from STi a crude granulated polyamide 6 material MPA2 and an aqueous stream SWA2;(p.3) passing the material MPA2 and preferably an aqueous stream SAQ2 to an extraction stage ST2, obtaining from ST2 a purified granulated polyamide 6 material MPA3 and an aqueous stream SWAS;(p.4) passing the material MPA3 to a drying stage ST3, obtaining from ST3 the polyamide 6 material MP and an aqueous stream SWA4.In particular regarding the process of the present invention comprising (p.1 ) to (p.4) above, it is preferred that the stream Swi obtained from Uci according to (y) is passed back to the polyamide 6 production plant UPA6. More preferably, the stream Swi is passed back to UPA6 as at least part of one or more of the streams SAQO, SAQI and SAQ2.Assuming that some of the polyamide 6 material obtained from the production plant UPAO does not meet the specifications, the process may preferably further comprise passing at least some of said material MPR to the unit UM.Further aspectsThe present invention also relates to a stream Ss2 and a stream SB3, comprising highly purified E-caprolactam, said streams being obtainable or obtained by a process as described herein, and a stream SPF, obtainable or obtained by a process as described herein.The present invention also relates to the use of the stream Ss2 and / or the stream SB3 and / or the stream SPF as described herein as an educt material for a chemical process, preferably for a polymerization reaction, more preferably for preparing polyamide 6.The present invention also relates to a method for preparing polyamide 6, comprising preparing a stream Ss2 and / or a stream SB3 according to a process as described herein, and / or a stream SPF as described herein; and subjecting the stream Ss2 and / or a stream SB3, preferably the stream SPF, optionally after storing, to polyamide 6 polymerization conditions. The present invention also relates to polyamide 6, obtainable or obtained by said method.The present invention also relates to the process as described herein, further comprising providing at least part of the stream Ss2 and / or at least a part of the stream SB3, and / or at least a part of the stream SPF, to a polyamide 6 production unit UPA6, wherein the polyamide 6 produced in UPA6 is preferably provided as a feedstock to a textile material producing unit UTP, from which unit UTP(A) a textile material MTE is obtained which is brought onto the market, wherein, after the lifetime TMTE of said textile material MTE, it is at least partially collected as textile waste material in a textile material collecting unit UTC;(B) remaining material MRE is obtained as textile waste material; wherein at least part of the textile waste material according to (A), or at least part of the textile waste material according to (B), or at least part of the textile waste material according to (A) and at least part of the textile waste material according to (B) is suitably provided as solid material M according to (i.2) as defined herein.The present invention also relates to the process as described herein, further comprising providing at least part of the stream Ss2 and / or at least a part of the stream SB3, and / or at least a part of the stream SPF, to a polyamide 6 production unit UPA6, wherein the polyamide 6 produced in UPA6 is preferably provided as a feedstock to an engineering plastics material producing unit UEP, from which unit UEP(A) an engineering plastics material MEP is obtained which is brought onto the market, wherein, after the lifetime TMEP of said engineering plastics material MEP, it is at least partially collected as engineering plastics waste material in an engineering plastics material collecting unit UEC;(B) remaining material MRE is obtained as engineering plastics waste material; wherein at least part of the engineering plastics waste material according to (A), or at least part of the engineering plastics waste material according to (B), or at least part of the engineering plastics waste material according to (A) and at least part of the engineering plastics waste material according to (B) is suitably provided as solid material M according to (i.2) as defined herein.According to yet another aspect, the present invention relates to a process, preferably a process as described herein, comprising the step of converting at least a part of the stream SB2 and / or at least a part of the stream STS and / or a chemical material obtainable or obtained by the process as described herein to obtain a product Q.Preferably, the product Q is selected from: building block or monomer; or polymer, preferably polymer A, polymer composition, preferably polymer composition A, or polymer product, preferably polymer product A; or cleaning polymer, cleaning surfactant, descaling compound, cleaning biocide or composition or formulation thereof; or agrochemical composition, agrochemical formulation auxiliary or agrochemically active ingredient; or active pharmaceutical ingredient or intermediate thereof, pharmaceutical excipient, animal feed additive, human food additive, dietary supplements, aroma chemical or aroma composition; or aqueous polymer dispersion, preferably polyurethane or polyurethane - poly(meth)acrylate hybrid polymer dispersion, emulsion, binder for paper and fiber coatings, UV-curable acrylic polymer for hot melts and coatings polyisocyanates, hyperbranched polyester polyol, polymeric dispersant for inorganic binder compositions, unsaturated polyester polyol or 100% curable composition; orcosmetic surfactant, emollient, wax, cosmetic polymer, UV filter, further cosmetic ingredient or composition or formulation thereof; or polymer B, polymer composition B, coating composition, other functional composition, foil, molded body, coating or coated substrate.Preferably, the content of the at least a part of the stream SB2 and / or the at least a part of the stream STS and / or the chemical material in the product Q is 1 weight-% or more, preferably 2 weight-% or more, more preferably 5 weight- % or more, more preferably 15 weight-% or more, more preferably 30 weight-% or more, more preferably 40 weight-% or more, more preferably 60 weight-% or more, more preferably 80 weight-% or more, more preferably 90 weight-% or more, more preferably 95 weight-% or more; and / or the content of the at least a part of the stream SB2 and / or the at least a part of the stream STS and / or the chemical material in the product Q is 100 weight-% or less, preferably 95 weight-% or less, more preferably 90 weight-% or less, more preferably 50 weight-% or less, more preferably 25 weight-% or less, more preferably 10 weight-% or less; and preferably wherein the content is determined based on identity preservation and / or segregation and / or mass balance and / or book and claim chain of custody models, preferably based on mass balance, preferably the International Sustainability and Carbon Certification (ISCC) standard.The publication Prior Art Disclosure; Issue 684; paragraphs

[1000] to

[8005] ; ISSN: 2198-4786; published: February 12, 2024 will be regarded as Reference RF1 , which is incorporated herein by reference in its entirety. Preferably, the product Q is a product as described in Reference RF1 ; paragraphs

[1000] to

[8005] , Preferably, the process described herein is further a process for the production of a product.The converting step to obtain the product Q preferably comprises one or more step(s) as described below and can be performed by conventional methods well known to a person skilled in the art. The converting step preferably comprises one or more step(s) selected from: recycling, preferably depolymerizing, gasifying, pyrolyzing, and / or steam cracking; and / or purifying, preferably crystallizing, (solvent) extracting, distilling, evaporating, hydrotreating, absorbing, adsorbing and / or subjecting to ion exchanger; and / or assembling, preferably foaming, synthesizing, chemical conversion, chemically transforming, polymerizing and / or compounding; and / or forming, preferably foaming, extruding and / or molding; and / or finishing, preferably coating and / or smoothing.In addition, the one or more step(s) are described in detail in Reference RF1 ; paragraphs

[1000] to

[8005] ,The term "building block”, as used in the context of the product Q herein, comprises compounds, which are in a gaseous or liquid state under standard conditions of 0°C and 0.1 MPa. Building blocks are typically used in chemical industry to form secondary products, which provide a higher structural complexity and / or higher molecular weight than the building block on which the secondary product is based. The building block is preferably selected from the groupconsisting of hydrogen, carbon monoxide, carbon dioxide, ethylene oxide, ethylene glycols, syngas comprising a mixture of hydrogen and carbon monoxide, alkanes, alkenes, alkynes and aromatic compounds. The alkanes, alkenes, alkynes and aromatic compounds comprise in particular 1 to 12 carbon atoms, respectively.The term "monomer”, as used in the context of the product Q herein, comprises molecules, which can react with each other to form polymer chains by polymerization. The monomer is preferably selected from the group consisting of (meth)acrylic acid, salts of (meth)acrylic acid; in particular sodium, potassium and zinc salts; (meth)acrolein and (meth)acrylates. (Meth)acrylates comprising 1 to 22 carbon atoms are preferred, in particular comprising 1 to 8 carbon atoms. The terms (meth)acrylic acid, (meth)acrolein or (meth)acrylate relate to acrylic acid, acrolein or acrylate and also to methacrylic acid, methacrolein or methacrylate, where applicable. Further, the monomer can be selected from hexamethylenediamine (HMD) and adipic acid.The building block can further be an intermediate compound. The term "intermediate compound”, as used in the context of the product Q herein, comprises organic reagents, which are applied for formation of compounds with higher molecular complexity. The intermediate compound can be selected for example from the group consisting of phosgene, polyisocyanates and propylene oxide. The polyisocyanates are in particular aromatic di- and polyisocyanates, preferably toluene diisocyanate (TDI) and / or diphenylmethane diisocyanate (MDI).The building block and the monomer and typical converting step(s) to obtain the building block or monomer are described in more detail in paragraphs

[1000] to

[1012] of Reference RF1.The term "polymer A”, as used in the context of the product Q herein, comprises thermoplastic, e.g., polyamide or thermoplastic polyurethane, thermoset, e.g., polyurethane, elastomer, e.g., polybutadiene, or a copolymer or a mixture thereof and is defined in more detail in paragraphs

[2001] to

[2007] of Reference RF1 . The term "polymer composition A”, as used in the context of the product Q herein, comprises all compositions comprising a polymer as described above and one or more additive(s), e.g. reinforcement, colorant, modifier and / or flame retardant, and is defined in more detail in paragraph

[2008] of Reference RF1 . The term "polymer product A”, as used in the context of the product Q herein, comprises any product comprising the polymer A and / or polymer composition A as described above and is defined in more detail in paragraphs

[2009] and

[2010] of Reference RF1. The step(s) to obtain the polymer, preferably polymer A, polymer composition, preferably polymer composition A or polymer product, preferably polymer product A is / are described in more detail in paragraph

[2011] of Reference RF1 .The term "industrial use polymer”, as used in the context of the product Q herein, comprises rheology, polycarboxylate, alkoxylated polyalkylenamine, alkoxylated polyalkylenimine, polyether-based, dye inhibition and soil release cleaning polymers defined in more detail in paragraphs

[3035] to

[3044] of Reference RF1. The term "industrial use surfactant”, as used in the context of the product Q herein, comprises non-ionic, anionic and amphoteric industrialuse surfactants defined in more detail in paragraphs

[3008] to

[3034] of Reference RF1 . The term "industrial use descaling compound”, as used in the context of the product Q herein, comprises non-phosphate based builders (NPB) and phosphonates (CoP) described in more detail in paragraphs

[3001] to

[3005] of Reference RF1. The term "industrial use biocide”, as used in the context of the product Q herein, refers to a chemical compound that kills microorganisms or inhibits their growth or reproduction defined in more detail in paragraphs

[3006] to

[3007] of Reference RF1 . The term "industrial use solvent”, as used in the context of the product Q herein, comprises alkyl amides, alkyl lactamides, alkyl esters, lactate esters, alkyl diester, cyclic alkyl diester, cyclic carbonates, aromatic aldehydes and aromatic esters defined in more detail in paragraphs

[3045] to

[3055] of Reference RF1. The term "industrial use dispersant”, as used in the context of the product Q herein, comprises anionic and non-ionic industrial use dispersants defined in more detail in paragraphs

[3056] to

[3058] of Reference RF1 . The term "composition and / or formulation thereof' with reference to the industrial use polymers, industrial use surfactants, descaling compounds and / or industrial use biocides refers to industrial use compositions and / or institutional use products and / or fabric and home care products and / or personal care products defined in more detail in paragraph

[3059] of Reference RF1. The converting step(s) to obtain the industrial use polymer, industrial use surfactant, descaling compound and / or industrial use biocide are defined in more detail in paragraph

[3060] of Reference RF1. The converting steps to obtain the industrial use composition or formulation of the industrial use polymer, industrial use surfactant, descaling compound and / or industrial use biocide are defined in more detail in paragraph

[3061] of Reference RF1.The term "agrochemical composition”, as used in the context of the product Q herein, typically relates to a composition comprising an agrochemically active ingredient and at least one agrochemical formulation auxiliary. Examples of agrochemical compositions, active ingredients and auxiliaries are described in more detail in Reference RF1 , paragraph

[4001] , The agrochemical composition may take the form of any customary formulation. The agrochemical compositions are prepared in a known manner, e.g. described by Mollet and Grubemann, Formulation technology, Wiley VCH, Weinheim, 2001 ; or Knowles, New developments in crop protection product formulation, Agrow Reports DS243, T&F Informa, London, 2005. The converting step(s) to obtain the agrochemically active ingredients and auxiliaries may be conducted in analogy to the production step(s) of their analogues that are based on petrochemicals or other precursors that are not gained by recycling processes. In addition, conversion to compounds mentioned in sections "Polymer” and "Cosmetic surfactant, emollient, wax, cosmetic polymer, UV filter, further cosmetic ingredient or compositions or formulations thereof' may be performed as described in these sections as well as the respective paragraphs in Reference RF1.The term active pharmaceutical ingredients and / or intermediates thereof, as used in the context of the product Q herein, comprises substances that provide pharmacological activity or other direct effect in the diagnosis, cure, mitigation, treatment, or prevention of disease, or to affect the structure or any function of the body. Intermediates thereof are isolated products that are generated during a multi-step route of synthesis of an active pharmaceutical ingredient. The term pharmaceutical excipients, as used in the context of the product Q herein, comprises com-pounds or compound mixtures used in compositions for various pharmaceutical applications, which are not substantially pharmaceutically active on itself. Active pharmaceutical ingredients and / or intermediates thereof and pharmaceutical excipients are defined in more detail in paragraph

[5001] of Reference RF1. The converting step(s) to obtain the active pharmaceutical ingredients and / or intermediates thereof and pharmaceutical excipients may comprise one or more synthesis steps and can be performed by conventional synthesis and techniques well known to a person skilled in the art.The terms animal feed additives, human food additives, dietary supplements, as used in the context of the product Q herein, comprises Vitamins, Pro-Vitamins and active metabolites thereof including intermediates and precursors, especially Vitamin A, B, E, D, K and esters thereof, like acetate, propionate, palmitate esters or alcohols thereof like retinol or salts thereof and any combinations thereof; Tetraterpenes, especially isoprenoids like carotenoids and xanthophylls including their intermediates and precursors as well as mixtures and derivates thereof, especially beta carotene, Canthaxanthin, Citranaxanthin, Astaxanthin, Zeaxanthin, Lutein, Lycopene, Apo-carotenoids, and any combinations thereof; organic acids, especially formic acid, propionic acid and salts thereof, such as sodium, calcium or ammonium salts, and any combinations thereof, such as but not limited to mixtures of formic acid and sodium formiate, propionic acid and ammonium propionate, formic acid and propionic acid, formic acid and sodium formiate and propionic acid, propionic acid and sodium propionate and formic acid and sodium formiate; glycerides of carboxylic acids and short and medium chain fatty acids, conjugated linoleic acids, such as omega-6 fatty acid (C18:2) methyl ester and 1 ,2-propandiol and beverage stabilizers, such as polyvinylpyrrolidone-polymer or polyvinylimidazole I polyvinylpyrrolidone-copolymer. Animal feed additives, human food additives and dietary supplements are defined in more detail in paragraph

[5002] of Reference RF1. The converting step(s) to obtain the animal feed additives, human food additives, dietary supplements may comprise one or more synthesis steps and can be performed by conventional synthesis and techniques well known to a person skilled in the art.The terms aroma chemical and aroma composition as used in the context of the product Q herein, comprise a volatile organic substance with a molecular weight between 70-250 g / mol comprising a functional group with a carbon skeleton of C5-C16 carbon atoms comprising linear, branched, cyclic, for example with a ring size of C5-C18, bicyclic or tricyclic aliphatic chains and but not necessarily one or more unsaturated structural elements like double bonds, triple bonds, aromatics or heteroaromatics and preferably the one or more additional functional groups are selected from alcohol, ether, ester, ketone, aldehyde, acetal, carboxylic acid, nitrile, thiol, amine. In one aspect, the aroma chemical is a terpene-based aroma chemical, for example selected from monoterpenes and monoterpenoids, sesquiterpenes and sesquiterpenoids, diterpenes, triterpenes or tetraterpenes. Aroma chemicals can be combined with further aroma chemicals to give an aroma composition. Aroma chemicals and aroma compositions are defined in more detail in paragraph

[5003] of Reference RF1 . The converting step(s) to obtain the aroma chemical and aroma composition may comprise one or more synthesis steps and can be performed by conventional synthesis and techniques well known to a person skilled in the art.The term "aqueous polymer dispersion”, as used in the context of the product Q herein, comprises aqueous compositions) comprising dispersed polymer(s) and is defined in more detail in the section

[6001] entitled "aqueous polymer dispersion” of Reference RF1. The dispersed polymer(s) may be selected from acrylic emulsion polymer(s), styrene acrylic emulsion polymer(s), styrene butadiene dispersion(s), aqueous dispersion(s) comprising composite particles, acrylate alkyd hybrid dispersion(s), polyurethane(s) (including UV-curable polyurethanes) and polyurethane - poly(meth)acrylate hybrid polymer(s). The term "emulsion polymer”, as used in the context of the product Q herein, comprises polymer(s) made by free-radical emulsion polymerization. Aqueous polyurethane dispersion(s) are defined in more detail in the section

[6002] entitled "Polyurethane dispersions” of Reference RF1. UV-curable polyure- thane(s) is / are defined in more detail in the section

[6017] of Reference RF1. Polyurethane - poly(meth)acrylate hybrid polymer(s) is / are defined in more detail in the section

[6016] of Reference RF1.The term "polymeric dispersant”, as used in the context of the product Q herein, comprises preferably polymer(s) comprising polyether side chain, in particular polycarboxylate ether polymer(s) and polycondensation product(s) defined in more detail in paragraph

[6020] entitled "Polymeric dispersant” of Reference RF1.The converting (polymerization) step(s) to obtain the aqueous polymer dispersion(s) comprising emulsion polymer(s) is / are defined in more detail in the section

[6003] entitled "Emulsion polymerization” of Reference RF1.The converting (polymerization) step(s) to obtain the aqueous polyurethane dispersion(s) is / are defined in more detail in the section

[6014] entitled "Process for the preparation of aqueous polyurethane dispersions” and section [6017)] entitled "Aqueous UV-curable polyurethane dispersions, their preparation and use and compositions containing them” of Reference RF1 .Composition(s) and uses of aqueous polymer dispersion(s) and of polymeric dispersant(s) are defined in more detail in the following sections of Reference RF1 : section

[6004] entitled "Uses of aqueous polymer dispersions”, section

[6005] entitled "Binders for architectural and construction coatings” section

[6006] entitled "Binders for paper coating” section

[6007] entitled "Binders for fiber bonding” section

[6008] entitled "Adhesive polymers and adhesive compositions” section

[6015] entitled "Aqueous polyurethane dispersions suitable for use in coating compositions” section

[6016] entitled "Aqueous polyurethane - poly(meth)acrylate hybride polymer dispersions suitable for use in coating compositions” section

[6017] entitled "Aqueous UV-curable polyurethane dispersions, their preparation and use and compositions containing them” section

[6018] entitled "Inorganic binder compositions comprising polymeric dispersants and their use”

[6019] 100% curable coating compositionsUV-crosslinkable poly(meth)acrylate(s) and its / their uses are defined in more detail in section

[6009] entitled "UV- crosslinkable poly(meth)acrylates for use in UV-curable solvent-free hotmelt adhesives and their use for making pressure-sensitive self-adhesive articles” of Reference RF1.Polyisocyanate(s), composition(s) comprising them and their uses are defined in more detail in section

[6010] entitled "Polyisocyanates” of Reference RF1.Hyperbranched polyester polyol(s) and its / their uses are defined in more detail in section

[6011] entitled "Organic solvent based hyperbranched polyester polyols suitable for use in coating compositions” of Reference RF1. The converting step(s) to obtain the hyperbranched polyester polyols is / are defined in more detail in the section

[6012] entitled "Preparation of organic solvent based hyperbranched polyester polyols” of Reference RF1 . Coating compositions) comprising hyperbranched polyester polyol(s), polyisocyanate(s) and additive(s) and substrate(s) coated therewith are defined in more detail in section

[6013] entitled "Organic solvent based two component coating compositions comprising hyperbranched polyester polyols and polyisocyanates” of Reference RF1.Unsaturated polyester polyol(s), solvent-based coating composition(s) comprising said unsaturated polyester pol- yol(s) and substrate(s) for coating with said coating composition(s) are defined in more detail in section

[6018] entitled "Organic solvent based coating composition comprising unsaturated polyester polyols” of Reference RF1. 100% curable coating composition(s) is / are defined in more detail in section

[6019] of Reference RF1.Polymeric dispersant(s) for inorganic binder compositions is / are defined in more detail in section

[6020] of Reference RF1. The inorganic binder composition(s) comprising the polymeric dispersants and their use are defined in more detail in section

[6021] of Reference RF1. The converting step(s) to obtain the polymeric dispersant(s) are defined in more detail in section

[6020] of Reference RF1. The term "inorganic binder composition” comprising the polymeric dispersant(s), as used in the context of the product Q herein, comprises preferably in particular hydraulically setting compositions and compositions comprising calcium sulfate and is defined in more detail in section

[6021] of Reference RF1 entitled "Inorganic binder compositions comprising the polymeric dispersant and their use”. Specific building material formulation(s) comprising polymeric dispersant(s) or building product(s) produced by a building material formulation comprising a polymeric dispersant are disclosed in more detail in section

[6021] of Reference RF1 .The term "cosmetic surfactant”, as used in the context of the product Q herein, comprises non-ionic, anionic, cationic and amphoteric surfactants and is defined in more detail in paragraph

[7002] of Reference RF1 . The term "emollient”, as used in the context of the product Q herein, refers to a chemical compound used for protecting, moisturizing, and / or lubricating the skin and is defined in more detail in paragraph

[7003] of Reference RF1 . The term "wax”, as used in the context of the product Q herein, comprises pearlizers and opacifiers and is defined in more detail in paragraph

[7004] of Reference RF1 . The term "cosmetic polymer”, as used in the context of the product Q herein, comprises any polymer that can be used as an ingredient in a cosmetic formulation and is defined in more detail in para-graph

[7005] of Reference RF1 . The term "UV filter”, as used in the context of the product Q herein, refers to a chemical compound that blocks or absorbs ultraviolet light and is defined in more detail in paragraph

[7006] of Reference RF1 . The term "further cosmetic ingredient”, as used in the context of the product Q herein, comprises any ingredient suitable for making a cosmetic formulation. Several sources disclose cosmetically acceptable ingredients. E. g. the database Cosing on the internet pages of the European Commission discloses cosmetic ingredients and the International Cosmetic Ingredient Dictionary and Handbook, edited by the Personal Care Products Council (PCPC), discloses cosmetic ingredients. The term "composition and / or formulation thereof' with reference to the cosmetic surfactant, emollient, wax, cosmetic polymer, UV filter and / or further cosmetic ingredient refers to personal care and / or cosmetic compositions or formulations defined in more detail in paragraph

[7007] of Reference RF1 . The converting step(s) to obtain the cosmetic surfactant, emollient, wax, cosmetic polymer, UV filter or further cosmetic ingredient is / are defined in more detail in paragraph

[7008] of Reference RF1.The terms "polymer B”, "polymer composition B”, "coating composition”, "other functional composition”, "foil”, "molded body”, "coating” and "coated substrate” are well known to the person skilled in the art and are defined in more detail from paragraph

[8000] to

[8005] of Reference RF1.The present invention is further illustrated by the following set of embodiments and combinations of embodiments resulting from the dependencies and back-references as indicated. In particular, it is noted that in each instance where a range of embodiments is mentioned, for example in the context of a term such as "The process of any one of embodiments 1 to 4", every embodiment in this range is meant to be explicitly disclosed for the skilled person, i.e. the wording of this term is to be understood by the skilled person as being synonymous to "The process of any one of embodiments 1, 2, 3 and 4". Further, it is explicitly noted that the following set of embodiments represents a suitably structured part of the general description directed to preferred aspects of the present invention, and, thus, suitably supports, but does not represent the claims of the present invention.1 . A process for the purification of an aqueous stream comprising E-caprolactam, the process comprising(i) providing an aqueous stream So comprising E-caprolactam at a concentration Cso(C), one or more organic compounds X at a total concentration Cso(X), one or more organic compounds Y at a total concentration cso(Y), and water at a concentration Cso(W), wherein water has a boiling point Tw, E-capro- lactam has a boiling temperature Tc, the one or more organic compounds X have a boiling temperature Tx, and the one or more organic compounds Y have a boiling temperature Ty, with Ty < Tc < Tx;(ii) separating water from the stream So, comprising a distillation in a first distillation column D 1, obtaining from Di a vapour top stream STI comprising water at a concentration CSTI(W) > Cso(W), and further obtaining from Di a liquid bottoms stream SBI comprising E-caprolactam at a concentration CSBI(C) > cso(C), the one or more organic compounds X at a total concentration CSBI(X) > cso(X), and the one or more organic compounds Y at a total concentration CSBI(Y) > cso(Y);(iii) separating the one or more compounds X from at least a part of the stream SBI, comprising a distillation in a second distillation column D2, obtaining from D2 a top stream ST2 comprising E-caprolactam at a concentration CST2(C) < CSBI(C) and the one or more organic compounds Y at a total concentration CST2(Y) > CSBI(Y), further obtaining from D2 a bottom stream SB2 comprising the one or more organic compounds X at a total concentration CSB2(X) > CSBI(X) and optionally E-caprolactam at a concentration CSB2(C) < CSBI(C), and obtaining from D2 a side stream Ss2 comprising E-caprolactam at a concentration css2(C) > CSBI(C);(iv) separating the one or more compounds Y from at least a part of the stream ST2, comprising a distillation in a third distillation column D3, obtaining from D3 a top stream STS comprising the one or more compounds Y at a total concentration CST3(Y) > CST2(Y), and obtaining from D3 a bottom stream SB3 comprising E-caprolactam at a concentration CSB3(C) > CST2(C).2. The process of embodiment 1 , wherein from 98 to 100 weight-%, preferably from 99 to 100 weight-%, more preferably from 99.5 weight-%, more preferably from 99.8 to 100 weight-% of the stream So consist of E-capro- lactam, the one or more compounds X, the one or more compounds Y, and water.3. The process of embodiment 1 or 2, wherein in the stream So, the weight ratio of E-caprolactam relative to water, m(C) / m(W), is in the range of from 1.5: 1 to 10:1 , preferably in the range of from 2: 1 to 9.5: 1 , more preferably in the range of from 2.5: 1 to 9:1.4. The process of any one of embodiments 1 to 3, wherein from 0.1 to 8 weight-%, preferably from 0.2 to 7 weight-%, more preferably from 0.5 to 6 weight-% of the stream So consist of the one or more compounds X and the one or more compounds Y.5. The process of any one of embodiments 1 to 4, wherein the stream So is a vapour stream, preferably having a pressure in the range of 75 to 125 mbar(abs) and temperature in the range of from 150 to 250 °C, more preferably in the range of from 155 to 200 °C, more preferably in the range of from 160 to 175 °C.6. The process of any one of embodiments 1 to 5, wherein the one or more compounds X comprise at least one of 1 -cyclopentene carboxylic acid; 3-cyclopentene carboxylic acid; 2-butyl-2-ethyl-1 ,3-propandiol; 2-hydroxy- ethyl-6-hydroxyhexane carboxylic acid ethyl ester; 2-naphthol, 1-cyclopentylazepane-2-on; 1 -hexadecanol (cetyl alcohol); 1 -octadecanol (stearyl alcohol); 6-nydroxy-N-(2,2,6,6-tetramethyl piperidine-4-yl)hexane amide; 1 ,8-diazacyclotetradecane-2,9-dion; MDA; di-(4-aminophenyl)-methane; 2,4-diaminodiphenylmethane; N- cyclopentylcaprolactam; 1-benzylazepan-2-on; tetrabutylene glycol; 7-hydroxyazepane-2-on; phthalic acid monomethyl ester; nonane diacid; and terephthalic acid.7. The process of any one of embodiments 1 to 6, wherein the one or more compounds Y comprise one or moreof 1-methoxypropane, neopentylglycol, 2,2-dimethylpropane-1 ,3-diol; 2-methylpropane-1 ,3-diol, aniline, 2,2,6,6-tetramethylpiperidine; 2,3,5,6-tetramethylpiperidin; 2-chloroaniline; caprolactone; N-methylcaprolac- tame; N-methylcaprolactame; N-propylcaprolactame; 1-dodecanol; hexahydro-2-oxo-1 H-azepin-1-propanal; hexahydro-2h-azepin-2-one; 2-hydroxyethyl-6-hydroxyhexane carboxylic acid ester; 7-hydroxy-N-(2, 2,6,6- tetramethyl piperidine-4-yl) heptanamide; 2-aminoethanol; N-methylbenzolamin; 2,3,5,6-tetramethylpiperidine; N-methylbenzolamine; 2-hydroxy-n-methylacetamide; 2-oxoazepan-1-carbaldehyde; N-methylacetamide; 2- methoxy-n-methylcyclohexan-1 -amine; 2-hydroxy-N-methylacetamide; and 7-hydroxyazepan-2-one. The process of any one of embodiments 1 to 7, wherein the distillation in Di according to (ii) is carried out at a temperature TDI at the bottom of Di and at pressure PDI at the top of Di , wherein PDI is preferably in the range of 75 to 125 mbar(abs) and TDI is preferably in the range of 100 to 120 °C, more preferably in the range of 105 to 120 °C, more preferably in the range of 110 to 120 °C. The process of any one of embodiments 1 to 8, wherein the distillation in Di according to (ii) is carried out at a reflux ratio in the range of from 0.2:1 to 0.9:1, preferably in the range of from 0.3:1 to 0.8:1, wherein the reflux ratio is defined as the mass flow ratio of the stream passed back to the top of Di relative to the stream So. The process of any one of embodiments 1 to 9, wherein at least 75 weight-%, preferably at least 80 weight-%, more preferably at least 85 weight-% of the stream STI obtained at the top of Di consist of water and optionally a part of the one or more compounds Y with Ty Tw. The process of any one of embodiments 1 to 10, wherein at most 500 weight-ppm, preferably at most 200 weight-ppm, more preferably at most 100 weight-ppm of the stream STI obtained at the top of Di consists of E- caprolactam. The process of any one of embodiments 1 to 11, wherein from 98 to 100 weight-%, preferably from 99 to 100 weight-%, more preferably from 99.5 weight-%, more preferably from 99.8 to 100 weight-% of the stream SBI consist of E-caprolactam, the one or more compounds X, the one or more compounds Y, and water, wherein preferably at most 5 weight-%, more preferably at most 2 weight-%, more preferably at most 1 weight-% of the stream SBI consist of water. The process of any one of embodiments 1 to 12, wherein the distillation in Di comprises subjecting the liquid bottom stream SBI having the temperature TDI to heating in a reboiler RDI, obtaining from RDI a vapour stream SBW and a liquid stream SBIL, the streams SBW and SBIL having a temperature TDI+ATDI, wherein ATDI is preferably in the range of from 5 to 15 K, wherein the stream SBW and preferably a part of the stream SBIL are passed back into the bottoms section of Di and the stream SBIL, preferably a part of the stream SBIL, is passed to (iii).14. The process of embodiment 13, wherein the reboiler RDI is configured as a film evaporator, preferably as a falling film evaporator.15. The process of embodiment 13 or 14, wherein from 98 to 100 weight-%, preferably from 99 to 100 weight-%, more preferably from 99.5 weight-%, more preferably from 99.8 to 100 weight-% of the stream SBIL consist of E-caprolactam, the one or more compounds X, the one or more compounds Y, and water, wherein preferably at most 5 weight-%, more preferably at most 2 weight-%, more preferably at most 1 weight-% of the stream SBI L consist of water.16. The process of any one of embodiments 1 to 15, wherein the distillation in D2 according to (ill) is carried out at a temperature TD2 at the bottom of D2 and at pressure pD2 at the top of D2, wherein pD2 is preferably in the range of from 2 to 8 mbar(abs), more preferably pD2 PDI and preferably TD2 > TDI, TD2 more preferably being in the range of from 110 to 160 °C, more preferably in the range of from 120 to 150 °C, more preferably in the range of from 130 to 140 °C.17. The process of any one of embodiments 1 to 16, wherein the distillation in D2 according to (ill) is carried out at a reflux ratio in the range of from 0.5:1 to 1.5:1, preferably in the range of from 0.6:1 to 0.9:1, more preferably in the range of from 0.7:1 to 0.9:1, wherein the reflux ratio is defined as the mass flow ratio of the stream passed back to the top of D2, relative to the stream SBI , preferably SBIL.18. The process of any one of embodiments 1 to 17, wherein at least 97 weight-%, preferably at least 98 weight- %, more preferably at least 99 weight-% of the stream ST2 obtained at the top of D2 consist of E-caprolactam and the one or more compounds Y, wherein in the stream ST2, the weight ratio of E-caprolactam relative to the one or more compounds Y, m(C) / m(Y), is at most 40: 1 , preferably at most 30: 1 , more preferably at most 20: 1 .19. The process of any one of embodiments 1 to 18, wherein at most 97 weight-%, preferably at most 96 weight- %, more preferably at most 95 weight of the stream ST2 obtained at the top of D2 consist of E-caprolactam.20. The process of any one of embodiments 1 to 19, wherein at least 97 weight-%, preferably at least 98 weight- %, more preferably at least 99 weight-% of the stream SB2 obtained at the bottom of D2 consist of E-capro- lactam, the one or more compounds X and optionally the one or more compounds Y, wherein in the stream SB2, the weight ratio of E-caprolactam relative to the one or more compounds X, m(C) / m(x), is at most 10:1, preferably at most 7:1, more preferably at most 4:1.21 . The process of any one of embodiments 1 to 20, wherein at least 95 weight-%, preferably at least 98 weight- % of the stream Ss2 obtained at the side of D2 consist of E-caprolactam.The process of any one of embodiments 1 to 21 , wherein at least 99 weight-%, preferably at least 99.5 weight-%, more preferably at least 99.9 weight-% of the stream Ss2 obtained at the side of D2 consist of s-ca- prolactam. The process of any one of embodiments 1 to 22, wherein the distillation in D3 according to (iv) is carried out at a temperature TD3 at the bottom of D3 and at pressure pD3 at the top of D3, wherein pD3 is preferably in the range of from 5 to 12 mbar(abs), more preferably pD3 pD2, more preferably pD3 > PD2, and preferably TD3 > TD2, TD3 more preferably being in the range of from 120 to 150 °C, more preferably in the range of from 130 to 150 °C, more preferably in the range of from 140 to 150 °C. The process of any one of embodiments 1 to 23, wherein the distillation in D3 according to (iv) is carried out at a reflux ratio in the range of from 0.6:1 to 0.95:1, preferably in the range of from 0.7:1 to 0.95:1, more preferably in the range of from 0.8:1 to 0.95:1, wherein the reflux ratio is defined as the mass flow ratio of the stream passed back to the top of D3 relative to the stream ST2. The process of any one of embodiments 1 to 24, wherein at least 97 weight-%, preferably at least 98 weight- %, more preferably at least 99 weight-% of the stream STS obtained at the top of D3 consist of E-caprolactam and the one or more compounds Y, wherein in the stream ST3, the weight ratio of E-caprolactam relative to the one or more compounds Y, m(C) / m(Y), is at most 9:1, preferably at most 7:1, more preferably at most 5:1. The process of any one of embodiments 1 to 25, wherein at least 98 weight-%, preferably at least 99 weight- %, more preferably at least 99.5 weight-% of the stream SB3 obtained at the bottom of D3 consist of E-capro- lactam and optionally the one or more compounds Y, wherein in the stream SB3, the weight ratio of E-capro- lactam relative to the one or more compounds Y, m(C) / m(Y) is preferably at least 99:1, more preferably at least 99.5: 11 , more preferably at least 99.8: 1 , more preferably at least 99.9: 1 . The process of embodiment 26, wherein in the stream SB3, the weight ratio of E-caprolactam relative to the one or more compounds Y, m(C) / m(Y), is greater than or equal to a pre-defined threshold value, the process further comprising(v.1) passing at least a part of the stream SB3 obtained at the bottom of the distillation column D3 to a downstream treatment stage, said downstream treatment stage preferably comprising a crystallization. The process of embodiment 26, wherein in the stream SB3, the weight ratio of E-caprolactam relative to the one or more compounds Y, m(C) / m(Y), is below a pre-defined threshold value, the process further comprising (v.2) passing at least a part of the stream SB3 obtained at the bottom of the distillation column D3 to an upstream treatment stage, said upstream treatment preferably comprising the distillation in the distillationcolumn D2, wherein more preferably, the at least a part of the stream SB3 is passed to the top of the distillation column D2. The process of any one of embodiments 1 to 28, further comprising(v.3) passing at least a part of the stream Ss2 obtained at the side of the distillation column D2 to a downstream treatment stage, said downstream treatment stage preferably comprising a crystallization. The process of any one of embodiments 1 to 29, further comprising(v.4) passing at least a part of a stream obtained from condensing the stream Ss2 obtained at the side of the distillation column D2, to an upstream treatment stage, said upstream treatment preferably comprising the distillation in the distillation column D2, wherein more preferably, the at least a part of the stream ST3 is passed to the top of the distillation column D2. The process of any one of embodiments 1 to 30, wherein the at least a part of the stream SBI obtained according to (ii), preferably the stream SBIL as defined in any one of embodiment 13 to 15, comprises one or more oxidizable organic impurity compounds Z and wherein downstream of separating water from the stream So according to (ii) and upstream of separating the one or more compounds X from at least a part of the stream SBI according to (iii), the process further comprises subjecting the at least a part of the stream SBI, preferably the stream SBIL as defined in any one of embodiment 13 to 15, to a chemical treatment stage, obtaining from said chemical treatment stage a chemically treated part of the stream SBI, preferably a chemically treated stream SBIL, which is then passed to separating the one or more compounds X according to (iii). The process of embodiment 31 , wherein one or more compounds Z are one or more compounds of the group of the one or more compounds X and / or one or more compounds of the group of the one or more compounds Y. The process of embodiment 31 or 32, wherein the one or more oxidizable compounds Z include one or more of diol compounds such as ethylene glycol, diethylene glycol, 1 ,4-butanediol, neopentylglycol, 2-methyl- 1,3-pentanediol; aromatic alcohols and amines such as phenol, 0- toluidine, m- toluidine, p-toluidine, aniline, diamino toluenes; aliphatic amines such as hexamethylene diamine, 4-amino-2,2,6,6-tetramethyl-piperidin, 2,2,6,6-tetra- methyl-piperidine, bis[2-(N,N-dimethylamino)-ethyl]ether. The process of any one of embodiments 31 to 33, wherein the chemical treatment stage comprises(a) providing a stream Sox comprising at least one oxidizing agent preferably comprising a permanganate;(b) preparing an oxidation reaction educt mixture MOE from the at least a part of the stream SBI, preferably the stream SBIL, and the stream Sox, and subjecting the mixture MOE to oxidation reaction conditions, obtaining an oxidation reaction product stream SOP comprising E-caprolactam, further comprising one or more oxidation reaction products ZP obtained from the oxidation of at least a part of the one or more compounds Z, and optionally further comprising a part of the one or more organic compounds Z;(c) passing the stream SOP, preferably after further treatment, as chemically treated part of the stream SBI , preferably as chemically treated stream SBIL, to separating the one or more compounds X according to (ill).35. The process of embodiment 34, wherein the at least one permanganate comprised in the stream Sox provided according to (a) comprises, preferably consists of, at least alkali metal permanganate, wherein more preferably, the at least one alkali metal permanganate comprises one or more of sodium permanganate and potassium permanganate.36. The process of embodiment 34 or 35, wherein from 0.5 to 100 weight-% of the stream Sox provided according to (a) consist of permanganate.37. The process of any one of embodiments 34 to 36, wherein the stream Sox provided according to (a) and the mixture MOE prepared according to (b) further comprise water.38. The process of any one of embodiments 34 to 37, wherein the oxidation reaction educt mixture MOE prepared according to (b) exhibits a permanganate concentration, calculated as Mn O4, in the range of from 0.005 to 5 weight-%, preferably in the range of from 0.01 to 3 weight-%, more preferably in the range of from 0.05 to 1 weight-%.39. The process of any one of embodiments 34 to 38, wherein subjecting the mixture MOE to oxidation reaction conditions is carried out in an oxidation reaction section UOR, wherein the reaction section UOR preferably comprises one or more of a stirred tank reactor, a dynamic mixer, a tube reactor, a static mixer, and an exit tube of said static mixer.40. The process of any one of embodiments 34 to 39, wherein the oxidation reactions conditions according to (b) comprise an oxidation reaction time AtoE in the range of from 5 min to 8 h and a temperature TOE in the range of from 20 to 140 °C, wherein if TOE is in the range of from 20 to 40 °C, AtoE is preferably in the range of from 2 to 8 h; if TOE is in the range of from 60 to 90 °C, AtoE is preferably in the range of from 15 to 45 min; if TOE is in the range of from 100 to 140 °C, AtoE is preferably in the range of from 5 to 15 min.41. The process of embodiment 40, wherein, if the temperature TOE is in the range of from 100 to 140 °C, the reaction section UOR as defined in embodiment 39 comprises, optionally consists of, a static mixer and an exit tube of said static mixer.42. The process of any one of embodiments 34 to 41 , wherein the further treatment according to (c) comprises subjecting the stream SOP, to a solid-liquid separation stage, preferably a filtration stage.43. The process of any one of embodiments 34 to 42, further comprising providing a stream SOB comprising at least one hydroxide, wherein the at least one hydroxide comprised in the stream SOB preferably comprises, more preferably consists of, at least alkali metal hydroxide, wherein more preferably, the at least one alkali metal hydroxide comprises, more preferably consists of, sodium hydroxide.44. The process of embodiment 43, wherein from 0.5 to 100 weight-% of the stream SOB consist of hydroxide, wherein the stream SB preferably further comprises water.45. The process of embodiment 43 or 44, wherein the stream SOB is passed into the process upstream of the chemical treatment stage, preferably into the distillation column Di, more preferably into the top of the distillation column Di; and / or during the chemical treatment stage, preferably either as a component for preparing the oxidation reaction educt mixture MOE according to (b); and / or admixing with the stream SOP, either upstream of and / or downstream of the solid-liquid separation as defined in embodiment 42; and / or downstream of the chemical treatment stage and upstream of separating the one or more compounds X according to (ill).46. The process of any one of embodiments 34 to 45, wherein the chemical treatment stage further comprises, at any point downstream of (ii) and upstream of (ill), an adsorption stage, wherein the respectively used adsorption agent preferably comprises charcoal, more preferably activated charcoal, wherein more preferably, said adsorption agent is arranged as a fixed adsorption bed.47. The process of embodiment 46, wherein the adsorption stage is arranged upstream of preparing the oxidation reaction educt mixture MOE according to (b).The process of any one of embodiments 31 to 47, wherein the apparatuses used in the chemical treatment stage comprise(A) at least one mixing device for preparing the oxidation reaction educt mixture MOE as defined in embodiment 34;(B) at least one oxidation reaction section UOR for subjecting the mixture MOE to oxidation reaction conditions as defined in embodiment 39;(C) at least one a solid-liquid separation section for subjecting the stream SOP to solid-liquid separation as defined in embodiment 42;(D) preferably at least one mixing device for admixing a stream SOB comprising at least one hydroxide as defined in embodiment 43;(E) optionally an adsorption device as defined in embodiment 46; wherein at least (A), (B), (C) and (D) are vertically arranged relative to each other. The process of any one of embodiments 1 to 48, wherein providing the aqueous stream So comprising s-ca- prolactam according to (I) comprises(1.1) providing a stream SM comprising a solid material M comprising polyamide 6;(1.2) preparing an aqueous depolymerization mixture MDI from SM;(1.3) subjecting the mixture MDI to a first depolymerization and purification stage, comprising(1.3.1) subjecting the mixture MDI in a depolymerization unit URI to polyamide 6 depolymerization conditions DRI comprising a depolymerization temperature TRI at a depolymerization pressure PRI, obtaining a liquid aqueous product stream SRI comprising monomeric E-caprolac- tam at a concentration CRI(C), polyamide 6 at a concentration CRI (P), one or more compounds X and one or more compounds Y;(1.3.2) passing the liquid aqueous stream SRI into a first water separation unit Uwsi, obtaining from SRI a liquid aqueous product stream Swsi comprising monomeric E-caprolactam at a concentration Cwsi(C) > CRI(C), polyamide 6 at a concentration Cwsi(P) > CRI(P), one or more compounds X and one or more compounds Y, and further obtaining at least one aqueous residue stream S .WSI comprising separated water;(1.3.3) passing the liquid aqueous stream Swsi into a high boiler separation unit UHSI, obtaining from Swsi an aqueous product stream SP-HSI comprising monomeric E-caprolactam at a concentration CR-HSI(C) > Cwsi(C), one or more compounds X at a total concentration CR-HSI(X) < cwsi(X)and one or more compounds Y, and further obtaining from Swsi an aqueous residue stream SR.HSI comprising polyamide 6 at a concentration CR-HSI(P) > Cwsi(P), one or more compounds X at a total concentration CR-HSI(X) > Cwsi(X) and optionally, in a residual amount, one or more compounds Y;(1.4) preferably passing the aqueous residue stream SR.HSI to further treatment, comprising(1.4.1) recycling at least a part of the stream SR.HSI to (ill), comprising subjecting the at least part of the stream SR.HSI in the depolymerization unit URI to the polyamide 6 depolymerization conditions DRI; and / or(1.4.2) subjecting at least a part of the stream SR.HSI to a second depolymerization and purification stage, comprising(1.4.2.1) subjecting the at least part of the stream SR.HSI in a depolymerization unit UR2 to polyamide 6 depolymerization conditions DR2 comprising a depolymerization temperature TR2 at a depolymerization pressure pR2, obtaining a liquid aqueous stream SR2 comprising monomeric E-caprolactam at a concentration CR2(C), optionally polyamide 6 at a concentration CR2(P) < CR_HSI(P), and optionally one or more compounds Y;(1.4.2.2) passing the liquid aqueous stream SR2 into a second water separation unit Uws2, obtaining from SR2 a liquid aqueous product stream Sws2 comprising monomeric E-caprolactam at a concentration cws2(C) > CR2(C), polyamide 6 at a concentration cws2(P) > CR2(P), one or more compounds X and optionally one or more compounds Y, and further obtaining at least one aqueous residue streamSR.WS2 comprising separated water;(1.4.2.3) passing the liquid aqueous stream Sws2 into a high boiler separation unit UHS2, obtaining from Sws2 an aqueous product streamSP-HS2 comprising monomeric E-caprolactam at a concentration CP-HS2(C) > cws2(C), optionally one or more compounds X and optionally one or more compounds Y, and further obtaining from Sws2 an aqueous residue stream SR-HS2 comprising one or more compounds X at a total concentration CR.HS2(X) > cws2(X), optionally polyamide 6 at a concentration CR.HS2(P) > cws2(P) and optionally one or more compounds Y;(1.4.2.4) passing the aqueous residue stream SR.HS2 to further treatment, comprising(1.4.2.4.1) recycling at least a part of the stream SR.HS2 to (i.4.2.1), comprising subjecting the at least part of the stream SR.HS2 in the depolymerization unit LWo the polyamide 6 depolymerization conditions DR2; and / or(1.4.2.4.2) passing at least a part of the stream SR.HS2 to a further use;(1.5) passing the aqueous product stream SP-HSI obtained according to (i.3.1), comprising monomeric s-ca- prolactam at the concentration CR-HSI (C), one or more compounds X, and one or more compounds Y and water at a concentration CR-HSI(W); and preferably the aqueous product stream SP-HS2 obtained according to (1.4.2.3), comprising monomeric E-caprolactam at the concentration CP-HS2(C), optionally one or more compounds X, optionally one or more compounds Y, and water at a concentration cp.HS2(W) to a third water separation unit Uws3, obtaining the aqueous stream So comprising E-capro- lactam at a concentration Cso(C), one or more organic compounds X at a total concentration cso(X), one or more organic compounds Y at a total concentration cso(Y), and water at a concentration Cso(W).50. The process of embodiment 49, further comprising recycling at least a part of the stream STI obtained at the top of the first distillation column to (i .2) as part of the aqueous depolymerization mixture MDI ; and / or to (1.4.2) as part of the at least a part of the stream SR.HSI to be subjected to a second depolymerization and purification stage according to (1.4.2.1).51 . The process of embodiment 49 or 50, further comprising recycling at least a part of the stream SB2 obtained at the bottom of the second distillation column to the high boiler separation unit UHSI according to (1.3.3) and / or the high boiler separation unit UHS2 according to (1.4.2.3).52. The process of any one of embodiments 49 to 51 , further comprising recycling at least a part of the stream STS obtained at the top of the third distillation column.53. The process of any one of embodiments 1 to 52, comprising(v.1 ) passing at least a part of the stream SB3 obtained at the bottom of the distillation column D3 to a downstream treatment stage comprising a crystallization; and / or(v.3) passing at least a part of the stream Ss2 obtained at the side of the distillation column D2 to a downstream treatment stage comprising a crystallization; obtaining from said crystallization an E-caprolactam product stream SPF.54. The process of embodiment 53, wherein the crystallization is carried out in a crystallization unit U comprising(1) h crystallization sub-units Uc(H), H = 1 ...h and h > 2, wherein each crystallization sub-unit UC<H) comprises s crystallizer WC(S(H», S(H) = 1 ...S and s > 1 ; a stream transportation line LC(H) passing through the s crystallizer WC(S(H», comprising an entry and exit point EC<H) connected to the stream distribution sub-unit UD according to (3) and further comprising controllable means MEC(HJ for passing a stream from UD into LC(H) and for passing a stream from LC(H) to UD;(2) a batch drum sub-unit UB comprising k batch drums B(i) with I = 1 ...k and k > 2, wherein each batch drum B(i) is equipped with controllable means MBO) for passing a stream from B(i) via the stream distribution sub-unit UD according to (3) to at least one of EC(H>; a crude E-caprolactam feed stream transportation line Lso to at least one batch drum B(i);(3) a stream distribution sub-unit UD connecting UB and the h sub-units UC<H), the sub-unit UD comprising(3.1) for each drum B(i) with i = 1...k(3.1.1) at least one of a stage stream transportation line Ls<Hi)(i) from B(i) to at least one Ec(W) and a stage stream transportation line Ls<H2)(i) from B(i) to at least one EC<H2), H1 + H2, wherein Ls<Hi)(i) comprises at least one controllable means MLS<HI)(I) for passing a stream from B(i) to EC<HI) and LS<H2)(I) comprises at least one controllable means MLS<H2)(I) for passing a stream from B(i) to EC(H2>;(3.1 .2) at least one of a back stream transportation line LB<H IJ(I) from EC<HI) to B(i) and a back stream transportation line LB<H2)(I) from Ec(H2) to B(i), wherein LB<HI)(I) comprises at least one controllable means MLB<HI)(I) for passing a stream from EC<HI) to B(i) and LB<H2)(I) comprises at least one controllable means MLB<H2)(I) for passing a stream from EC(H2> to B(i);(3.2) a final residue stream transportation line LR<H3) , H3 + H1,H2, for removing a final crystallization residue stream SRF from a transportation line LC(H) via EC<H), wherein LR<H3) comprises at least one controllable means MLR<H3) for removing said final residue stream SRF from LC(H>;(3.3) a final fine product stream transportation line LF(H4), H4 + H1,H2,H3, for removing a final fine crystallization product stream SPF from a transportation line LC<H) via EC(H), wherein LF<H4) comprises at least one controllable means MLF<H4) for removing said final fine product stream SPF from LC(H>; the process comprising(I) passing the at least a part of the stream STS and / or the at least a part of the stream Ss2 into a batch drum B(i), 1 < I < k;(II) subjecting the content of the batch drum B(i) to crystallization comprising n crystallization stages P(x) carried out in at least one sub-unit UC<H2) with 1 < n < (k-i+1) and x = 1 ...n, and further comprising m crystallization stages C(y) carried out in at least one sub-unit UC<HI) with 0 < m < (i-1) and y = 1...m for m > 0, wherein H1 + H2;(11.1) wherein a crystallization stage P(x) comprises(11.1.1) passing a stage stream Ss(x+i-1) comprising at least a part of the content of a batch drum B(x+i-1 ) from said batch drum B(x+i-1 ) via the transportation line Ls<H2)(x+i-1 ) and the entry and exit point EC<H2) into the transportation line LC(H2>;(11.1.2) passing the stream Ss(x+i-1) through the transportation line LC<H2) with the means Mc(H2), thereby passing through the at least one crystallizer Wc(s(H2», wherein in Wc(s(H2», E-caprolactam comprised in Ss(x+i-1 ) crystallizes and remains as crystallized solid in Wc(s(H2»;(11.1.3) removing a residue stream SR(X+I-1 ) from the transportation line Lc(H2) via EC<H2), wherein the stream SR(X+I-1 ) is depleted in E-caprolactam compared to the stream Ss(x+i-1); and(1.3.1) passing the stream SR(X-H-1) via the transportation line LR<H3> as final residue stream SRF via MLR<H3) to optional further use; or(1 .3.2) passing the stream SR(X+I-1 ) via the transportation line LB(H2)(X-H-2) into the batch drum B(x+i-2);(11.1.4) transferring the crystallized solid in Wc(s(H2» into a liquid product stream Sp(x+i-1);(11.1.5) removing the stream Sp(x+i-1) from the transportation line LC<H2) via EC<H2), wherein the stream Sp(x+i-1 ) is concentrated in E-caprolactam compared to the stream Ss(x+i- 1), and(1.5.1) passing the stream Sp(x+i-1) via the transportation line LF<H4) as final E- caprolactam fine product stream SPF via MLF<H4) to further use; or(1 .5.2) passing the stream Sp(x+i-1 ) via the transportation line LB(H2)(X-H) into the batch drum B(x+i);(II.2) wherein a crystallization stage C(y) comprises(11.2.1) passing a stage stream Ss(i-y) comprising at least a part of the content of a batch drum B(i-y) from said batch drum B(i-y) via the transportation line Ls<Hi)(i-y) and the entry and exit point EC<HI) into the transportation line LC(HI>;(11.2.2) passing the stream Ss(i-y) through the transportation line LC(HI) with the means MC(HI), thereby passing through the at least one crystallizer WC(S(HI», wherein in WC(S(HI», E-caprolactam comprised in Ss(i-y) crystallizes and remains as crystallized solid in WC(S(HI»;(11.2.3) removing a residue stream SR(i-y) from the transportation line LC(HI), wherein the stream SR(i-y) is depleted in E-caprolactam compared to the stream Ss(i-y); and(2.3.1) passing the stream SR(i-y) via the transportation line LR<H3) as final residue stream SRF via MLR(H3> to optional further use; or(2.3.2) passing the stream SR(i-y) via the transportation line LB<Hi)(i-y-1 ) into the batch drum B(i-y-1);(11.2.4) transferring the crystallized solid in WC(S(HI» into a liquid product stream Sp(i-y);(11.1.5) removing the stream Sp(i-y) from the transportation line LC(HI> via EC(HI>, wherein the stream Sp(i-y) is concentrated in E-caprolactam compared to the stream Ss(i-y), and passing the stream Sp(i-y) via the transportation line Ls<Hi)(i-y+1) into the batch drum B(i-y+1). The process of any one of embodiments 1 to 54, preferably according to embodiment 54, further comprising (a) passing the stream Ss2 and / or the stream SB3, preferably the stream SPF according to (11.1.5.1) as defined in embodiment 54, to a polyamide 6 production plant UPAG;(p) subjecting the stream Ss2 and / or the stream SB3, preferably the stream SPF, to E-caprolactam polymerization conditions, obtaining from UPA6 a polyamide 6 material MP and a stream comprising water andone or more E-caprolactam oligomers;(y) optionally subjecting to stream comprising water and one or more E-caprolactam oligomers to concentration with respect to the one or more E-caprolactam oligomers in at least one concentration stage, obtaining a concentrated stream comprising water and one or more E-caprolactam oligomers;(5) passing the optionally concentrated stream comprising water and one or more E-caprolactam oligomers into at least one of the melting unit UM as defined herein and the water separation unit Uwsi as defined herein. A stream Ss2 and a stream SB3, comprising highly purified E-caprolactam, said streams being obtainable or obtained by a process according to any one of embodiments 1 to 52, and a stream SPF, obtainable or obtained by a process according to embodiment 53 or 54. Use of the stream Ss2 and / or the stream SB3 according to embodiment 56 as an educt material for a chemical process, preferably for a polymerization reaction, more preferably for preparing polyamide 6. A method for preparing polyamide 6, comprising preparing a stream Ss2 and / or a stream SB3 according to a process according to any one of embodiments 1 to 52, and / or a stream SPF according to embodiment 53 of 54; and subjecting the stream Ss2 and / or a stream SB3, preferably the stream SPF, optionally after storing, to polyamide 6 polymerization conditions. Polyamide 6, obtainable or obtained by a method according to embodiment 58. The process of any one of embodiments 1 to 52, or according to embodiment 53 or 54, further comprising providing at least part of the stream Ss2 and / or at least a part of the stream SB3, and / or at least a part of the stream SPF, to a polyamide 6 production unit UPA6, wherein the polyamide 6 produced in UPA6 is preferably provided as a feedstock to a textile material producing unit UTP, from which unit UTP(A) a textile material MTE is obtained which is brought onto the market, wherein, after the lifetime TMTE of said textile material MTE, it is at least partially collected as textile waste material in a textile material collecting unit UTC;(B) remaining material MRE is obtained as textile waste material; wherein at least part of the textile waste material according to (A), or at least part of the textile waste material according to (B), or at least part of the textile waste material according to (A) and at least part of the textile waste material according to (B) is suitably provided as solid material M according to (1.2) as defined in embodiment 49. The process of any one of embodiments 1 to 52, or according to embodiment 53 or 54, further comprising providing at least part of the stream Ss2 and / or at least a part of the stream SB3, and / or at least a part of thestream SPF, to a polyamide 6 production unit UPA6, wherein the polyamide 6 produced in UPA6 is preferably provided as a feedstock to an engineering plastics material producing unit UEP, from which unit UEP(A) an engineering plastics material MEP is obtained which is brought onto the market, wherein, after the lifetime TMEP of said engineering plastics material MEP, it is at least partially collected as engineering plastics waste material in an engineering plastics material collecting unit UEC;(B) remaining material MRE is obtained as engineering plastics waste material; wherein at least part of the engineering plastics waste material according to (A), or at least part of the engineering plastics waste material according to (B), or at least part of the engineering plastics waste material according to (A) and at least part of the engineering plastics waste material according to (B) is suitably provided as solid material M according to (1.2) as defined in embodiment 49. A process, preferably according to any one of embodiments 1 to 55, comprising the step of converting at least a part of the stream SB2 and / or at least a part of the stream STS and / or a chemical material obtainable or obtained by the process according to any one of embodiments 1 to 55 to obtain a product Q. The process of embodiment 62, wherein the product Q is selected from: building block or monomer; or polymer, preferably polymer A, polymer composition, preferably polymer composition A, or polymer product, preferably polymer product A; or cleaning polymer, cleaning surfactant, descaling compound, cleaning biocide or composition or formulation thereof; or agrochemical composition, agrochemical formulation auxiliary or agrochemically active ingredient; or active pharmaceutical ingredient or intermediate thereof, pharmaceutical excipient, animal feed additive, human food additive, dietary supplements, aroma chemical or aroma composition; or aqueous polymer dispersion, preferably polyurethane or polyurethane - poly(meth)acrylate hybrid polymer dispersion, emulsion, binder for paper and fiber coatings, UV-curable acrylic polymer for hot melts and coatings polyisocyanates, hyperbranched polyester polyol, polymeric dispersant for inorganic binder compositions, unsaturated polyester polyol or 100% curable composition; or cosmetic surfactant, emollient, wax, cosmetic polymer, UV filter, further cosmetic ingredient or composition or formulation thereof; or polymer B, polymer composition B, coating composition, other functional composition, foil, molded body, coating or coated substrate. The process of embodiment 62 or 63, wherein the content of the at least a part of the stream SB2 and / or the at least a part of the stream STS and / or the chemical material in the product Q is 1 weight-% or more, preferably 2 weight-% or more, more preferably5 weight-% or more, more preferably 15 weight-% or more, more preferably 30 weight-% or more, more preferably 40 weight-% or more, more preferably 60 weight-% or more, more preferably 80 weight-% or more, more preferably 90 weight-% or more, more preferably 95 weight-% or more; and / or wherein the content of the at least a part of the stream SB2 and / or the at least a part of the stream STS and / or the chemical material in the product Q is 100 weight-% or less, preferably 95 weight-% or less, more preferably 90 weight-% or less, more preferably 50 weight-% or less, more preferably 25 weight-% or less, more preferably 10 weight-% or less; and preferably wherein the content is determined based on identity preservation and / or segregation and / or mass balance and / or book and claim chain of custody models, preferably based on mass balance, preferably the International Sustainability and Carbon Certification (ISCC) standard.It is explicitly noted that the above-disclosed set of embodiments represents a suitably structured part of the general description directed to preferred aspects of the present invention, and, thus, suitably supports, but does not represent the claims of the present invention.The term „bar" as used in the context of the present invention refers to the absolute pressure, also referred to as „bar(abs)“ or as "bara”.The term "textile material” as used herein covers textile raw materials and non-textile raw materials that are processed by various methods into linear, planar and spatial structures. It concerns the linear textile structures produced from them, such as yarns, twisted yarns and ropes, the sheet-like textile structures, such as woven fabrics, knitted fabrics, braids, stitch-bonded fabrics, nonwovens and felts, and the three-dimensional textile structures, i.e. body structures, such as textile hoses, stockings or textile semi-finished products; and it further concerns those finished products which, using the aforementioned products, are brought into a saleable condition by making up, opening up and / or other operations for onward transmission to the processor, the trade or the end consumer. The term "textile waste material” as used herein covers a textile material as defined above, the inherent value of which has been consumed from the perspective of its current holder and, thus, is an end-of-life material for said holder.The term "engineering plastics” as used herein refers to high-performance plastics grades which possess physical properties enabling them to perform for prolonged use in structural applications, over a wide temperature range, under mechanical stress, and in difficult chemical and physical environments used for example to fabricate plastic parts replacing traditional engineering materials like metals and ceramics. Engineering plastics specifically apply in the fabrication of mechanical parts across several industries such as automotive, medical, electrical and electronics, aerospace, construction and consumer products. The term "engineering plastics waste material” as used herein covers an engineering plastics material as defined above, the inherent value of which has been consumed from the perspective of its current holder and, thus, is an end-of-life material for said holder.

Claims

Claims1 . A process for the purification of an aqueous stream comprising E-caprolactam, the process comprising(i) providing an aqueous stream So comprising E-caprolactam at a concentration Cso(C), one or more organic compounds X at a total concentration cso(X), one or more organic compounds Y at a total concentration cso(Y), and water at a concentration Cso(W), wherein water has a boiling point Tw, E-capro- lactam has a boiling temperature Tc, the one or more organic compounds X have a boiling temperature Tx, and the one or more organic compounds Y have a boiling temperature Ty, with Ty < Tc < Tx;(ii) separating water from the stream So, comprising a distillation in a first distillation column D 1, obtaining from Di a vapour top stream STI comprising water at a concentration CSTI(W) > Cso(W), and further obtaining from Di a liquid bottoms stream SBI comprising E-caprolactam at a concentration CSBI(C) > Cso(C), the one or more organic compounds X at a total concentration CSBI(X) > cso(X), and the one or more organic compounds Y at a total concentration CSBI(Y) > cso(Y);(ill) separating the one or more compounds X from at least a part of the stream SBI, comprising a distillation in a second distillation column D2, obtaining from D2 a top stream ST2 comprising E-caprolactam at a concentration CST2(C) < CSBI(C) and the one or more organic compounds Y at a total concentration CST2(Y) > CSBI(Y), further obtaining from D2 a bottom stream SB2 comprising the one or more organic compounds X at a total concentration CSB2(X) > CSBI(X) and optionally E-caprolactam at a concentration CSB2(C) < CSBI(C), and obtaining from D2 a side stream Ss2 comprising E-caprolactam at a concentration css2(C) > CSBI(C);(iv) separating the one or more compounds Y from at least a part of the stream ST2, comprising a distillation in a third distillation column D3, obtaining from D3 a top stream STS comprising the one or more compounds Y at a total concentration CST3(Y) > CST2(Y), and obtaining from D3 a bottom stream SB3 comprising E-caprolactam at a concentration CSB3(C) > CST2(C).

2. The process of claim 1, wherein from 98 to 100 weight-%, preferably from 99 to 100 weight-%, more preferably from 99.5 weight-%, more preferably from 99.8 to 100 weight-% of the stream So consist of E-caprolactam, the one or more compounds X, the one or more compounds Y, and water, and wherein preferably from 0.1 to 8 weight-%, more preferably from 0.2 to 7 weight-%, more preferably from 0.5 to 6 weight-% of the stream So consist of the one or more compounds X and the one or more compounds Y, the stream So preferably being a vapour stream, preferably having a pressure in the range of 75 to 125 mbar(abs) and temperature in the range of from 150 to 250 °C, more preferably in the range of from 155 to 200 °C, more preferably in the range of from 160 to 175 °C.

3. The process of claim 1 or 2, wherein the one or more compounds X comprise at least one of 1 -cyclopentene carboxylic acid; 3-cyclopentene carboxylic acid; 2-butyl-2-ethyl-1 ,3-propandiol; 2-hydroxyethyl-6-hydroxyhex-ane carboxylic acid ethyl ester; 2-naphthol, 1-cyclopentylazepane-2-on; 1 -hexadecanol (cetyl alcohol); 1 -octa- decanol (stearyl alcohol); 6-hydroxy-N-(2,2,6,6-tetramethyl piperidine-4-yl)hexane amide; 1 ,8-diazacyclotetra- decane-2,9-dion; MDA; di-(4-aminophenyl)-methane; 2,4-diaminodiphenylmethane; N-cyclopentylcaprolac- tam; 1-benzylazepane-2-on; tetrabutylene glycol; 7-hydroxyazepane-2-on; phthalic acid monomethyl ester; nonane diacid; and terephthalic acid; and wherein the one or more compounds Y comprise one or more of 1- methoxypropane, neopentylglycol, 2,2-dimethylpropane-1 ,3-diol; 2-methylpropane-1 ,3-diol, aniline, 2, 2,6,6- tetramethyl-piperidine; 2,3,5,6-tetramethylpiperidin; 2-chloroaniline; caprolactone; N-methylcapro-lactame; N- methylcaprolactame; N-propylcaprolactame; 1 -dodecanol; hexahydro-2-oxo-1 H-azepin-1-propanal; hexahy- dro-2h-azepin-2-one; 2-hydroxyethyl-6-hydroxyhexane carboxylic acid ester; 7-hydroxy-N-(2,2,6,6-tetramethyl piperidine-4-yl) heptanamide; 2-aminoethanol; N-methylbenzolamin; 2,3,5,6-tetramethylpiperidine; N- methylbenzolamine; 2-hydroxy-n-methylacetamide; 2-oxoazepan-1-carbaldehyde; N-methylacetamide; 2- methoxy-n-methylcyclohexan-1 -amine; 2-hydroxy-N-methylacetamide; and 7-hydroxy-azepan-2-one.

4. The process of any one of claims 1 to 3, wherein the distillation in Di according to (ii) is carried out at a temperature TDI at the bottom of Di and at pressure PDI at the top of D 1, wherein PDI is preferably in the range of 75 to 125 mbar(abs) and TDI is preferably in the range of 100 to 120 °C, more preferably in the range of 105 to 120 °C, more preferably in the range of 110 to 120 °C.

5. The process of any one of claims 1 to 4, wherein the distillation in Di comprises subjecting the liquid bottom stream SBI having the temperature TDI to heating in a reboiler RDI, obtaining from RDI a vapour stream SBW and a liquid stream SBIL, the streams SBIV and SBIL having a temperature TDI+ATDI, wherein ATDI is preferably in the range of from 5 to 15 K, wherein the stream SBIV and preferably a part of the stream SBIL are passed back into the bottoms section of Di and the stream SBIL, preferably a part of the stream SBIL, is passed to (ill), wherein the reboiler RDI is preferably configured as a film evaporator, more preferably as a falling film evaporator.

6. The process of any one of claim 1 to 5, wherein the distillation in D2 according to (ill) is carried out at a temperature TD2 at the bottom of D2 and at pressure pD2 at the top of D2, wherein pD2 is preferably in the range of from 2 to 8 mbar(abs), more preferably pD2 PDI and preferably TD2 > TDI , TD2 more preferably being in the range of from 110 to 160 °C, more preferably in the range of from 120 to 150 °C, more preferably in the range of from 130 to 140 °C.

7. The process of any one of claims 1 to 6, wherein the distillation in D3 according to (iv) is carried out at a temperature TD3 at the bottom of D3 and at pressure pD3 at the top of D3, wherein pD3 is preferably in the range of from 5 to 12 mbar(abs), more preferably pD3 pD2, more preferably pD3 > PD2, and preferably TD3 > TD2, TD3 more preferably being in the range of from 120 to 150 °C, more preferably in the range of from 130 to 150 °C, more preferably in the range of from 140 to 150 °C.

8. The process of any one of claims 1 to 7, wherein in the stream SB3, the weight ratio of E-caprolactam relative to the one or more compounds Y, m(C) / m(Y), is greater than or equal to a pre-defined threshold value, the process further comprising(v.1) passing at least a part of the stream SB3 obtained at the bottom of the distillation column D3 to a downstream treatment stage, said downstream treatment stage preferably comprising a crystallization; or wherein in the stream SB3, the weight ratio of E-caprolactam relative to the one or more compounds Y, m(C) / m(Y), is below a pre-defined threshold value, the process further comprising(v.2) passing at least a part of the stream SB3 obtained at the bottom of the distillation column D3 to an upstream treatment stage, said upstream treatment preferably comprising the distillation in the distillation column D2, wherein more preferably, the at least a part of the stream SB3 is passed to the top of the distillation column D2.

9. The process of any one of claims 1 to 8, further comprising(v.3) passing at least a part of the stream Ss2 obtained at the side of the distillation column D2 to a downstream treatment stage, said downstream treatment stage preferably comprising a crystallization.

10. The process of any one of claims 1 to 9, wherein the at least a part of the stream SBI obtained according to (II), preferably the stream SBIL as defined in claim 5, comprises one or more oxidizable organic impurity compounds Z and wherein downstream of separating water from the stream So according to (II) and upstream of separating the one or more compounds X from at least a part of the stream SBI according to (ill), the process further comprises subjecting the at least a part of the stream SBI, preferably the stream SBIL as defined in claim 5, to a chemical treatment stage, obtaining from said chemical treatment stage a chemically treated part of the stream SBI , preferably a chemically treated stream SBIL, which is then passed to separating the one or more compounds X according to (ill), wherein the chemical treatment stage preferably comprises(a) providing a stream Sox comprising at least one oxidizing agent preferably comprising a permanganate;(b) preparing an oxidation reaction educt mixture MOE from the at least a part of the stream SBI, preferably the stream SBIL, and the stream Sox, and subjecting the mixture MOE to oxidation reaction conditions, obtaining an oxidation reaction product stream SOP comprising E-caprolactam, further comprising one or more oxidation reaction products ZP obtained from the oxidation of at least a part of the one or more compounds Z, and optionally further comprising a part of the one or more organic compounds Z;(c) passing the stream SOP, preferably after further treatment, as chemically treated part of the stream SBI , preferably as chemically treated stream SBIL, to separating the one or more compounds X according to (iii)i wherein subjecting the mixture MOE to oxidation reaction conditions is preferably carried out in an oxidation reaction section UOR, wherein the reaction section UOR preferably comprises one or more of a stirred tank reactor, a dynamic mixer, a tube reactor, a static mixer, and an exit tube of said static mixer;wherein the oxidation reactions conditions according to (b) preferably comprise an oxidation reaction time AtoE in the range of from 5 min to 8 h and a temperature TOE in the range of from 20 to 140 °C, wherein if T OE is in the range of from 20 to 40 °C, AtoE is preferably in the range of from 2 to 8 h; if TOE is in the range of from 60 to 90 °C, AtoE is preferably in the range of from 15 to 45 min; if TOE is in the range of from 100 to 140 °C, AtoE is preferably in the range of from 5 to 15 min.11 . The process of claim 10, further comprising providing a stream SOB comprising at least one hydroxide, wherein the at least one hydroxide comprised in the stream SOB preferably comprises, more preferably consists of, at least alkali metal hydroxide, wherein more preferably, the at least one alkali metal hydroxide comprises, more preferably consists of, sodium hydroxide, wherein the stream SOB is passed into the process upstream of the chemical treatment stage, preferably into the distillation column Di, more preferably into the top of the distillation column Di; and / or during the chemical treatment stage, preferably either as a component for preparing the oxidation reaction educt mixture MOE according to (b); and / or admixing with the stream SOP, either upstream of and / or downstream of the solid-liquid separation as defined in embodiment 42; and / or downstream of the chemical treatment stage and upstream of separating the one or more compounds X according to (ill).

12. The process of claim 10 or 11 , wherein the chemical treatment stage further comprises, at any point downstream of (ii) and upstream of (ill), an adsorption stage, wherein the respectively used adsorption agent preferably comprises charcoal, more preferably activated charcoal, wherein more preferably, said adsorption agent is arranged as a fixed adsorption bed, wherein the adsorption stage is preferably arranged upstream of preparing the oxidation reaction educt mixture MOE according to (b).

13. The process of any one of claims 1 to 12, wherein providing the aqueous stream So comprising E-caprolactam according to (I) comprises(1.1) providing a stream SM comprising a solid material M comprising polyamide 6, the solid material M comprised in the stream SM preferably comprising, more preferably consisting of, a waste material, wherein said waste material more preferably comprises, more preferably consists of, one or more of at least one textile waste material and at least one engineering plastics waste material, more preferably comprises, more preferably consists of at least one textile waste material;(1.2) preparing an aqueous depolymerization mixture MDI from SM;(1.3) subjecting the mixture MDI to a first depolymerization and purification stage, comprising(1.3.1) subjecting the mixture MDI in a depolymerization unit URI to polyamide 6 depolymerization conditions DRI comprising a depolymerization temperature TRI at a depolymerization pressure PRI, obtaining a liquid aqueous product stream SRI comprising monomeric E-caprolac- tam at a concentration CRI(C), polyamide 6 at a concentration CRI (P), one or more compounds X and one or more compounds Y;(1.3.2) passing the liquid aqueous stream SRI into a first water separation unit Uwsi, obtaining from SRI a liquid aqueous product stream Swsi comprising monomeric E-caprolactam at a concentration Cwsi(C) > CRI(C), polyamide 6 at a concentration Cwsi(P) > CRI(P), one or more compounds X and one or more compounds Y, and further obtaining at least one aqueous residue stream S .WSI comprising separated water;(1.3.3) passing the liquid aqueous stream Swsi into a high boiler separation unit UHSI, obtaining from Swsi an aqueous product stream SP-HSI comprising monomeric E-caprolactam at a concentration CP-HSI(C) > Cwsi(C), one or more compounds X at a total concentration CP-HSI(X) < cwsi(X)and one or more compounds Y, and further obtaining from Swsi an aqueous residue stream SR.HSI comprising polyamide 6 at a concentration CR.HSI(P) > Cwsi(P), one or more compounds X at a total concentration CR.HSI(X) > Cwsi(X) and optionally, in a residual amount, one or more compounds Y;(1.4) preferably passing the aqueous residue stream SR.HSI to further treatment, comprising(1.4.1) recycling at least a part of the stream SR.HSI to (ill), comprising subjecting the at least part of the stream SR.HSI in the depolymerization unit URI to the polyamide 6 depolymerization conditions DRI; and / or(1.4.2) subjecting at least a part of the stream SR.HSI to a second depolymerization and purification stage, comprising(1.4.2.1) subjecting the at least part of the stream SR.HSI in a depolymerization unit UR2 to polyamide 6 depolymerization conditions DR2 comprising a depolymerization temperature TR2 at a depolymerization pressure pR2, obtaining a liquid aqueous stream SR2 comprising monomeric E-caprolactam at a concentration CR2(C), optionally polyamide 6 at a concentration CR2(P) < CR.HSI (P), and optionally one or more compounds Y;(1.4.2.2) passing the liquid aqueous stream SR2 into a second water separation unit Uws2, obtaining from SR2 a liquid aqueous product stream Sws2 comprising monomeric E-caprolactam at a concentration cws2(C) > CR2(C), polyamide 6 at a concentration cws2(P) > CR2(P), one or more compounds X and optionally one or more compounds Y, and further obtaining at least one aqueous residue stream SR.WS2 comprising separated water;(1.4.2.3) passing the liquid aqueous stream Sws2 into a high boiler separation unit UHS2, obtaining from Sws2 an aqueous product stream SP-HS2 comprising monomeric E-caprolactam at a concentration CP-HS2(C) > cws2(C), optionally one or more compounds X and optionally one or more compounds Y, and further obtaining from Sws2 an aqueous residue stream SR.HS2 comprising one or more compounds X at a total concentration CR.HS2(X) > cws2(X), optionally polyamide 6 at a concentration CR-HS2(P) > cws2(P) and optionally one or more compounds Y;(i .4.2.4) passing the aqueous residue stream SR.HS2 to further treatment, comprising(1.4.2.4.1) recycling at least a part of the stream SR.HS2 to (i.4.2.1), comprising subjecting the at least part of the stream SR.HS2 in the depolymerization unit LWo the polyamide 6 depolymerization conditions DR2; and / or(1.4.2.4.2) passing at least a part of the stream SR.HS2 to a further use;(i.5) passing the aqueous product stream SP-HSI obtained according to (i.3.1), comprising monomeric s-ca- prolactam at the concentration CP-HSI (C), one or more compounds X, and one or more compounds Y and water at a concentration CP-HSI(W); and preferably the aqueous product stream SP-HS2 obtained according to (i .4.2.3), comprising monomeric E-caprolactam at the concentration CP-HS2(C), optionally one or more compounds X, optionally one or more compounds Y, and water at a concentration cp. HS2(W) to a third water separation unit Uws3, obtaining the aqueous stream So comprising E-capro- lactam at a concentration Cso(C), one or more organic compounds X at a total concentration cso(X), one or more organic compounds Y at a total concentration cso(Y), and water at a concentration cso(W); the process preferably further comprising one or more of, more preferably two or more of recycling at least a part of the stream STI obtained at the top of the first distillation column to (i .2) as part of the aqueous depolymerization mixture MDI ; and / or to (i .4.2) as part of the at least a part of the stream SR.HSI to be subjected to a second depolymerization and purification stage according to (i.4.2.1); recycling at least a part of the stream SB2 obtained at the bottom of the second distillation column to the high boiler separation unit UHSI according to (i.3.3) and / or the high boiler separation unit UHS2 according to (i.4.2.3); recycling at least a part of the stream STS obtained at the top of the third distillation column.

14. The process of any one of claims 1 to 13, comprising(v.1 ) passing at least a part of the stream SB3 obtained at the bottom of the distillation column D3 to a downstream treatment stage comprising a crystallization; and / or(v.3) passing at least a part of the stream Ss2 obtained at the side of the distillation column D2 to a downstream treatment stage comprising a crystallization; obtaining from said crystallization an E-caprolactam product stream SPF; wherein the crystallization is preferably carried out in a crystallization unit U comprising(1) h crystallization sub-units Uc(H), H = 1 ...h and h > 2, wherein each crystallization sub-unit UC<H) comprises s crystallizer WC(S(H», S(H) = 1...S and s > 1; a stream transportation line LC(H) passing through the s crystallizer WC(S(H», comprising an entry and exit point EC<H) connected to the stream distribution sub-unit UD according to (3) and further comprising controllable means MEC(HJ for passing a stream from UD into LC(H) and for passing a stream from LC(H) to UD;(2) a batch drum sub-unit UB comprising k batch drums B(i) with i = 1 ...k and k > 2, wherein each batch drum B(i) is equipped with controllable means MB(I) for passing a stream from B(i) via the stream distribution sub-unit UD according to (3) to at least one of EC(H>; a crude E-caprolactam feed stream transportation line Lso to at least one batch drum B(i);(3) a stream distribution sub-unit UD connecting UB and the h sub-units UC<H), the sub-unit UD comprising(3.1) for each drum B(i) with i = 1...k(3.1.1) at least one of a stage stream transportation line Ls<Hi)(i) from B(i) to at least one Ec(W) and a stage stream transportation line Ls<H2)(i) from B(i) to at least one EC<H2), H1 + H2, wherein Ls<Hi)(i) comprises at least one controllable means MLS<HI)(I) for passing a stream from B(i) to EC<HI) and Ls<H2)(i) comprises at least one controllable means MLS<H2)(I) for passing a stream from B(i) to EC(H2>;(3.1 .2) at least one of a back stream transportation line LB<H i)(i) from EC<HI) to B(i) and a back stream transportation line LB<H2)(i) from Ec(H2) to B(i), wherein LB(HI)O) comprises at least one controllable means MLB<HI)(I) for passing a stream from EC<HI) to B(i) and Ls(H2)(i) comprises at least one controllable means MLB<H2)(I) for passing a stream from EC(H2> to B(i);(3.2) a final residue stream transportation line LR<H3) , H3 + H1,H2, for removing a final crystallization residue stream SRF from a transportation line LC(H) via EC<H), wherein LR<H3) comprises at least one controllable means MLR<H3) for removing said final residue stream SRF from LC(H>;(3.3) a final fine product stream transportation line LF(H4), H4 + H1,H2,H3, for removing a final fine crystallization product stream SPF from a transportation line LC<H) via EC(H), wherein LF<H4) comprises at least one controllable means MLF<H4) for removing said final fine product stream SPF from LC(H>; the process comprising(I) passing the at least a part of the stream STS and / or the at least a part of the stream Ss2 into a batch drum B(i), 1 < i < k;(II) subjecting the content of the batch drum B(i) to crystallization comprising n crystallization stages P(x) carried out in at least one sub-unit UC<H2) with 1 < n < (k-i+1) andx = 1 ...n, and further comprising m crystallization stages C(y) carried out in at least one sub-unit UC<HI) with 0 < m < (i-1) and y = 1 ...m for m > 0, wherein H1 + H2;(11.1) wherein a crystallization stage P(x) comprises(11.1.1) passing a stage stream Ss(x+i-1) comprising at least a part of the content of a batch drum B(x+i-1 ) from said batch drum B(x+i-1 ) via the transportation line LS(H2)(X-H-1 ) and the entry and exit point EC<H2) into the transportation line LC(H2>;(11.1.2) passing the stream Ss(x+i-1) through the transportation line LC<H2) with the means Mc(H2), thereby passing through the at least one crystallizer Wc(s(H2», wherein in Wc(s(H2», E-caprolactam comprised in Ss(x+i-1 ) crystallizes and remains as crystallized solid in Wc(s(H2»;(11.1.3) removing a residue stream SR(X+I-1 ) from the transportation line Lc(H2) via EC<H2), wherein the stream SR(X+I-1 ) is depleted in E-caprolactam compared to the stream Ss(x+i-1); and(1.3.1) passing the stream SR(X+I-1 ) via the transportation line LR<H3) as final residue stream SRF via MLR<H3) to optional further use; or(1 .3.2) passing the stream SR(X+I-1 ) via the transportation line LB(H2)(X-H-2) into the batch drum B(x+i-2);(11.1.4) transferring the crystallized solid in Wc(s(H2» into a liquid product stream Sp(x+i-1);(11.1.5) removing the stream Sp(x+i-1) from the transportation line LC<H2) via EC<H2), wherein the stream Sp(x+i-1 ) is concentrated in E-caprolactam compared to the stream Ss(x+i- 1), and(1.5.1) passing the stream Sp(x+i-1) via the transportation line LF<H4) as final E- caprolactam fine product stream SPF via MLF<H4) to further use; or(1 .5.2) passing the stream Sp(x+i-1 ) via the transportation line LB(H2)(X-H) into the batch drum B(x+i);(11.2) wherein a crystallization stage C(y) comprises(11.2.1) passing a stage stream Ss(i-y) comprising at least a part of the content of a batch drum B(i-y) from said batch drum B(i-y) via the transportation line Ls<Hi)(i-y) and the entry and exit point EC<HI) into the transportation line LC(HI>;(11.2.2) passing the stream Ss(i-y) through the transportation line LC(HI) with the means MC(HI), thereby passing through the at least one crystallizer WC(S(HI», wherein in WC(S(HI», E-caprolactam comprised in Ss(i-y) crystallizes and remains as crystallized solid in WC(S(HI»;(11.2.3) removing a residue stream SR(i-y) from the transportation line LC(HI), wherein the stream SR(i-y) is depleted in E-caprolactam compared to the stream Ss(i-y); and(2.3.1) passing the stream SR(i-y) via the transportation line LR<H3) as final residue stream SRF via MLR(H3> to optional further use; or(2.3.2) passing the stream SR(i-y) via the transportation line LB<Hi)(i-y-1 ) into the batch drum B(i-y-1 );(11.2.4) transferring the crystallized solid in WC(S(HI» into a liquid product stream Sp(i-y);(11.1.5) removing the stream Sp(i-y) from the transportation line LC(HI> via EC<HI), wherein the stream Sp(i-y) is concentrated in E-caprolactam compared to the stream Ss(i-y), and passing the stream Sp(i-y) via the transportation line Ls<Hi)(i-y+1) into the batch drum B(i-y-nl); the process optionally or preferably further comprising(a) passing the stream Ss2 and / or the stream SB3, preferably the stream SPF, to a polyamide 6 production plant UPA6;(p) subjecting the stream Ss2 and / or the stream SB3, preferably the stream SPF, to E-caprolactam polymerization conditions, obtaining from UPA6 a polyamide 6 material MP and a stream comprising water and one or more E-caprolactam oligomers;(y) optionally subjecting to stream comprising water and one or more E-caprolactam oligomers to concentration with respect to the one or more E-caprolactam oligomers in at least one concentration stage, obtaining a concentrated stream comprising water and one or more E-caprolactam oligomers;(5) passing the optionally concentrated stream comprising water and one or moreE-caprolactam oligomers into at least one of the melting unit UM as defined herein and the water separation unit Uwsi as defined herein.

15. A process, preferably according to any one of claims 1 to 14, comprising the step of converting at least a part of the stream SB2 and / or at least a part of the stream STS and / or a chemical material obtainable by or obtained by the process according to any one of claims 1 to 14 to obtain a product Q.

Images