Method for treating wastewater having an organic content

Abstract

The present invention relates to a method for reducing the total organic carbon of a wastewater stream obtained from the pyrolysis of a feedstock and / or from treating a pyrolysis oil with an aqueous solution in which phase separation of an aqueous solution into a wastewater stream a1´ and an organic waste phase o1 and thereby the total organic carbon content TOC of the wastewater stream is reduced. The reduction of the total organic carbon content TOC allows a simplified wastewater treatment and optionally the recovery of desired molecules from said wastewater stream.

Description

[0001] Method for treating wastewater having an organic content

[0002] Technical area

[0003] The present invention relates to a method for treating wastewater having an organic content. The wastewater derives as a side product from the pyrolysis of a feedstock and / or from treating a pyrolysis oil with an aqueous solution e.g., for adjusting the pH value of such pyrolysis oils.

[0004] Background of the invention

[0005] Pyrolysis oil obtained by a pyrolysis reaction from a feedstock such as mixed plastic waste, waste tires, and other kinds of waste are considered a source for base chemicals in the chemical industry. Base chemicals derived from such pyrolysis oils comprise syngas obtained by partial oxidation, and (light-)olefins and aromatics obtained by thermal cracking processes such as steam cracking.

[0006] The pyrolysis reaction is a thermal reaction wherein the reactants are heated to a temperature in the range of about 350 °C to about 900 °C in an inert atmosphere. The most valuable product of the pyrolysis reaction is a pyrolysis oil. Water comprising organic compounds is also usually formed as a side product during such a pyrolysis reaction. Such water is considered a wastewater stream and often has a total organic carbon content (TOC) too high for treatment in standard wastewater facilities. Such water formed as a side product during a pyrolysis reaction usually has an acidic pH value or in case alkaline substances such as KOH and / or Ca(OH)2 are added to the feedstock for the pyrolysis reaction, the resulting wastewater stream may also have a neutral or an alkaline pH value. Said water portion (an aqueous solution) of the pyrolysis oil is separated from the pyrolysis oil and thereby forms a wastewater stream which requires a dedicated wastewater treatment because of its high total organic carbon content (TOC).

[0007] The pyrolysis oil is then subjected to several further purification steps to remove solid particles, remove and / or convert compounds comprising heteroatoms from the pyrolysis oil and so on. A common method to remove various impurities from pyrolysis oils and / or to modify the pyrolysis oil to be better suited for further process steps is treating the pyrolysis oil with an aqueous solution for adjusting the pH value of the pyrolysis oil. Said aqueous solution preferably has an alkaline pH value in case the pyrolysis oil subjected to such a pH adjustment has an initial acidic pH value prior to said pH adjustment.

[0008] At least a portion of organic compounds such as carboxylic acids, phenols, and organic amines which are considered impurities in the pyrolysis oil are transferred thereby from the pyrolysis oil into said aqueous solution used for adjusting the pH value of the pyrolysis oil. Due to the different polarities of the pyrolysis oil and the aqueous solution used for pH value adjustment of the pyrolysis oil both components (pyrolysis oil and aqueous solution) form two phases after a settling period and can then be separated from each other. The aqueous solution used for adjusting the pH value of the pyrolysis oil receives impurities from the pyrolysis oil which results in a wastewater stream having a total organic carbon content (TOC) of, for example, 4 wt.-% to 15 wt.- % or more which is usually too high for treatment in standard wastewater facilities. Furthermore, such wastewater streams may also comprise non-biodegradable organic compounds which are undesired and need to be removed from the wastewater and non-biodegradable organic compounds present in the wastewater.

[0009] Accordingly, different methods are known in prior art used to reduce the total organic carbon content (TOC) of the above-described wastewater streams. For example, stripping with e.g., nitrogen gas and / or steam is used to remove low-boiling organic compounds from such wastewater streams. Such methods are not suitable to remove organic compounds having a high boiling point such as for example benzoic acid and fatty acids from such wastewater streams. Other methods suitable for reducing the total organic carbon content (TOC) of such wastewater streams comprise adsorption, extraction with organic solvents, distillation, membrane filtration and combinations thereof.

[0010] Such methods may not sufficiently reduce such a high total organic carbon content (TOC) and the concentration of non-biodegradable compounds in wastewater streams obtained after separation of the water phase formed as a side product during the pyrolysis reaction from the pyrolysis oil and / or by treating the pyrolysis oil with an aqueous solution for adjusting for example the pH value of pyrolysis oils to a level which then allows further treatment of the wastewater streams in standard wastewater facilities.

[0011] In particular, adsorption fails with a such a high total organic carbon content (TOC) because the adsorbents are spent too fast. Extraction as a sole method to reduce the total organic carbon content (TOC) produces a large amount of contaminated organic solvents which needs to be treated with e.g., distillation for reuse which renders such a method uneconomical because of high investment costs. Distillation as a method for reducing the total organic carbon content (TOC) in such wastewater has for example a high energy consumption in case organic components and water are separated by evaporation of the water. When using a membrane technology for reducing the total organic carbon content (TOC), an alkaline pH value of e.g., 10, an increased temperature, the presence of organic solvents and solid particles can lead to a failure of the process.

[0012] CN 115504608 A discloses a method and equipment for treating oily coal chemical wastewater, from coal chemical production processes such as coking, coal gasification, and coal pyrolysis. Accordingly, the feedstock is coal. Said method and equipment is suited to remove phenol and ammonia from said wastewater by extraction with an organic solvent.

[0013] A coal chemical process wastewater advanced treatment system for treating the wastewater from a thermal process converting the feedstock coal, the system including a degreasing tank, a deacidification and ammonia removal tank, a high-speed centrifuge, a catalytic wet oxidation regulation tank, a catalytic wet oxidation tower, a biological regulation tank, and an A / O biochemical system is disclosed in CN 110713305 A. The wastewater is initially treated by increasing the pH value (deacidified in a deacidification and deamination tank 3). Accordingly, the thermal treatment feedstock is coal.

[0014] CN 115925201 A discloses a treatment system and a treatment method for oily sludge which is produced in the process of oil exploitation, production and processing and is then converted by a pyrolysis reaction into other products including water which is denoted "oily sludge pyrolysis water” in this document. Accordingly, the pyrolysis feedstock is oily sludge. The system for treating wastewater described therein is based on flocculation and solid-liquid separation using a membrane system. A pH adjustment system is optionally installed between the nanofiltration membrane system and the dish-type reverse system membrane system.

[0015] CN 112047550 A discloses a system treating wastewater from coal chemical production processes such as coking, coal gasification, and coal pyrolysis. Accordingly, the feedstock is coal. The system for treating such wastewater is aimed to recover phenol and ammonia. The system includes, in this order, a pre-adsorption pH adjustment device, an adsorption reactor, an adsorbent high-efficiency separator and an adsorbent thermal regenerator. Further pH adjustment devices are utilized before dephenolization and deamination. Organic molecules comprised in said wastewater are removed therefrom by adsorption and filtration.

[0016] Hence, there is a need to provide a method for reducing the total organic carbon content (TOC) and remove non- biodegradable organic compounds from wastewater stream obtained after separation of the water phase formed as a side product during the pyrolysis reaction from the pyrolysis oil and / or by treating the pyrolysis oil with an aqueous solution e.g., for adjusting the pH value of pyrolysis oils which results in a wastewater stream having a total organic carbon content (TOC) and a concentration of non-biodegradable organic compounds low enough to allow a treatment of the wastewater stream in a standard wastewater facility.

[0017] Furthermore, recovery of precious organic compounds such as s-caprolactam from such wastewater streams for later use in e.g., the manufacture of polyamide-6 is also desired during reduction of the total organic carbon content (TOC) of such wastewater streams.

[0018] Summary of the invention

[0019] This problem is solved by a method for reducing the total organic carbon content of a wastewater stream obtained from the pyrolysis of a feedstock and / or from treating a pyrolysis oil with an aqueous solution, the method for reducing the total organic carbon content of a wastewater stream obtained from the pyrolysis of a feedstock and / or from treating a pyrolysis oil with an aqueous solution, the method comprising the steps

[0020] (I) providing a mixture comprising a pyrolysis oil and an aqueous solution a1, the aqueous solution a1 selected from the group consisting of

[0021] (la) aqueous solution b1 formed together with said pyrolysis oil by a pyrolysis reaction of a feedstock, wherein said feedstock is selected from the group comprising or preferably consisting of plastic waste, rubber waste, bio waste and mixtures thereof,

[0022] (ib) aqueous solution c2 formed after contacting said pyrolysis oil with an aqueous solution d,

[0023] (ii) separating the aqueous solution b1 and / or c2 from said pyrolysis oil and thereby obtain a wastewater stream a1 ', wherein the wastewater stream a1 ' has a first total organic carbon content TOC1,

[0024] (ill) initiating a separation of the wastewater stream a1 ' into a wastewater stream a1 " having a first volume V1 and a second total organic carbon content TOC2, and an organic waste phase o1 having a second volume V2, wherein the second total organic carbon content TOC2 is smaller than the first total organic carbon content TOCIand wherein said separation is initiated in step (ill) by adding

[0025] (a) at least one acidic aqueous solution to the wastewater stream a1 ' and / or

[0026] (b) adding at least one salt to the wastewater stream a1 ' and / or

[0027] (c) adding at least a portion of aqueous solution b1 to aqueous solution c2 and wherein the feedstock is selected from the group comprising plastic waste, rubber waste, bio waste and mixtures thereof.

[0028] This problem is further solved by a system for reducing the total organic carbon content of a wastewater stream obtained from the pyrolysis of a feedstock and / or from treating a pyrolysis oil with an aqueous solution, the system comprising a first containment unit, a first liquid-liquid separation unit which is downstream of and fluidically connected to the first containment unit, a second containment unit which is downstream of and fluidically connected to the first liquid-liquid separation unit, at least one dosing unit which is fluidically connected to the second containment unit, optionally, a solid separation unit which is downstream of and fluidically connected to the second containment unit, optionally a second liquid-liquid separation unit which is downstream of and fluidically connected to the second containment unit or downstream of and fluidically connected to the optional solid separation unit, wherein said at least one dosing unit utilizes pH measurement and / or mass measurement for dosing.

[0029] The mode of operation for the method according to the present invention can be batchwise or continuous. Furthermore, the wastewater stream a1 ' (obtained from aqueous solution b1 and / or c2) can be treated in step (ill) separately or combined in any combination desired and useful for the overall wastewater treatment process including the successive treatments in standard wastewater treatment facilities.

[0030] Surprisingly, the method according to the present invention results in a reduction of the total organic carbon content (TOC) in the wastewater stream obtained from the pyrolysis reaction, and / or treatment of a pyrolysis oil with an aqueous solution. Furthermore, the organic components removed from the wastewater stream are concentrated in an organic phase having a small volume in comparison with the resulting aqueous waste phase having the reduced total organic carbon content (TOC).

[0031] Detailed description of the invention

[0032] The present invention is further described below with reference to the embodiments, but the present invention is not limited to these embodiments, and any modifications of these embodiments, combinations of these embodiments or substitutions within the basic spirit of the present invention are still within the scope of the present invention as claimed.

[0033] Definitions:

[0034] In the context of the present description and the accompanying claims, the term "about” preferably means a deviation of the thus described value of ±10%.

[0035] In the context of the present invention, the term “combinations thereof” is inclusive of one or more of the recited elements.

[0036] In the context of the present invention, the term “mixture thereof” is inclusive of one or more of the recited elements.

[0037] In the context of the present invention, the term “pyrolysis” relates to a thermal decomposition or degradation of a feedstock such as plastic waste under inert conditions and results in a gas, a liquid, and a solid char fraction. During the pyrolysis, the feedstock is converted into a great variety of chemicals including gases such as H2, Ci- to C4- alkanes, C2- to C4-alkenes, ethyne, propyne, 1 -butyne, pyrolysis oil having a boiling temperature of 25 °C to 500 °C and char. In addition, water is formed during the pyrolysis which may be partially dispersed in the pyrolysis oil and may be partially contacted with the pyrolysis oil in a separate phase. The water formed during pyrolysis comprises various organic compounds and / or salts thereof which were also formed during the pyrolysis. The term “pyrolysis” includes slow pyrolysis, fast pyrolysis, flash catalysis and catalytic pyrolysis. These pyrolysis types differ regarding process temperature, heating rate, residence time, feed particle size, etc. resulting in different product quality.

[0038] In the context of the present invention, the term “pyrolysis oil” is understood to mean any oil originating from the pyrolysis of feedstocks selected from the group comprising or preferably consisting of plastic waste, rubber waste, bio waste and mixtures thereof. The pyrolysis oil is obtained and / or obtainable from pyrolysis of feedstocks selected from the group comprising or preferably consisting of plastic waste, rubber waste, bio waste and mixtures thereof. A “pyrolysis oil” comprises an oil phase, a mixture of carboxylic acids and / or salts thereof, and water. In the context of the present invention, the term "plastic waste” also refers to any plastic material discarded after use, i.e., the plastic material has reached the end of its useful life and is considered post-consumer waste. The plastic waste can be pure polymeric plastic waste, mixed plastic waste or film waste, including soiling, adhesive materials, fillers, residues etc. The plastic waste may have an oxygen content, a nitrogen content, sulfur content, halogen content and optionally also a heavy metal content. The plastic waste can originate from any plastic material containing source.

[0039] Accordingly, the term "plastic waste” includes industrial and domestic plastic waste and including used tires and agricultural and horticultural plastic material. The term "plastic waste” also includes used petroleum-based hydrocarbon material such as used motor oil, machine oil, greases, waxes, etc.

[0040] Preferably,, plastic waste is a mixture of different plastic materials, including hydrocarbon plastics, e.g., polyolefins such as polyethylene (HDPE, LDPE) and polypropylene, polystyrene, and copolymers thereof, etc., and polymers composed of carbon, hydrogen, and other elements such as chlorine, fluorine, oxygen, nitrogen, sulfur, silicone, etc., for example chlorinated plastics, such as polyvinylchloride (PVC), polyvinylidene chloride (PVDC), etc., nitrogencontaining plastics, such as polyamides (PA), polyurethanes (PU), acrylonitrile butadiene styrene (ABS), etc., oxy- gen-containing plastics such as polyesters, e.g., polyethylene terephthalate (PET), polycarbonate (PC), etc., silicones and / or sulfur bridges crosslinked rubbers.

[0041] Preferably, the plastic material comprises additives, such as processing aids, plasticizers, flame retardants, pigments, light stabilizers, lubricants, impact modifiers, antistatic agents, antioxidants, etc. These additives may comprise elements other than carbon and hydrogen. For example, bromine is mainly found in connection to flame retardants. Heavy metal compounds may be used as lightfast pigments and / or stabilizers in plastics. Cadmium, zinc, and lead may be present in heat stabilizers and slip agents used in plastics manufacturing. The plastic waste can also contain residues. Residues in the sense of the invention are contaminants adhering to the plastic waste. The additives and residues are usually present in an amount of less than 50 wt.-%, preferably less than 30 wt.-%, more preferably less than 20 wt.-%, even more preferably less than 10 wt.-%, based on the total weight of the dry weight plastic.

[0042] Examples of rubber waste include end-of-life tires, rubber waste produced during manufacturing processes and discarded rubber containing products such as latex examining gloves and gaskets. End-of-life tires comprise further ingredients such as textiles and organic and inorganic additives which may be separated from the rubber portion of end-of-life tires prior to pyrolysis. Pyrolysis oils obtained by pyrolysis of (predominantly) end-of-life tires are also known as tire pyrolysis oils (TPO).

[0043] Examples of bio waste include green waste, food waste, human waste, manure, sewage, sewage sludge and slaughterhouse waste. To obtain the pyrolysis oil according to the present invention, the feedstock is inserted into a pyrolysis reactor using a dosing unit such as for example a screw or an extruder or a rotary valve or a pneumatic conveyor or a liquid injector. The feedstock is optionally pre-heated in e.g., a heat exchanger prior to insertion into the pyrolysis reactor and / or subjected to a pre-pyrolysis at a temperature in the range of, for example, from about 200 °C to about 360 °C. Next, the feedstock is heated in the pyrolysis reactor to a temperature in the range of from about 350 °C to about 900 °C, more preferably in the range of from 400 °C to about 550 °C, and a pressure in the range of from about 0.5 bar to about 2 bar(abs), more preferably in the range of from 0.9 bar to about 1.5 bar(abs). The pyrolysis reactor is preferably selected from the group comprising fluidized bed reactors, moving bed reactors, entrained flow reactors, screw reactors, extruders, stirred tank reactors and rotary kiln reactor. Preferably, the pyrolysis is performed in the pyrolysis reactor under an inert atmosphere exempt of oxygen or air.

[0044] Pyrolysis processes as such are known. They are described, e.g., in EP 0713906 A1 and WO 95 / 03375 A1. Suitable pyrolysis oils are also commercially available. The pyrolysis oil is typically a liquid at 15 °C or a wax at said temperature. "Liquid at 15 °C” in the terms of the present invention means that the pyrolysis oil has a density of at most 1 .3 g / ml, e.g., a density in the range from 0.65 to 0.98 g / ml, at 15 °C and 1013 mbar, as determined according to DIN EN ISO 12185.

[0045] A pyrolysis oil is optionally mixed (blended) with at least one other pyrolysis oil and / or fraction thereof such as 1 wt.- % to 99 wt.-% at least one other pyrolysis oil and / or fraction thereof or 10 wt.-% at least one other pyrolysis oil and / or fraction thereof or 20 wt.-% at least one other pyrolysis oil and / or fraction thereof or 30 wt.-% at least one other pyrolysis oil and / or fraction thereof or 40 wt.-% at least one other pyrolysis oil and / or fraction thereof or 50 wt.-% at least one other pyrolysis oil and / or fraction thereof or 60 wt.-% at least one other pyrolysis oil and / or fraction thereof or 70 wt.-% at least one other pyrolysis oil and / or fraction thereof or 80 wt.-% at least one other pyrolysis oil and / or fraction thereof or 90 wt.-% at least one other pyrolysis oil and / or fraction thereof.

[0046] Preferably, the pyrolysis oil or at least one of the pyrolysis oils in case at least two pyrolysis oils are mixed (blended) has a heating value (measured according to DIN 51900) of about 35 kJ / g to about 46 kJ / g and / or preferably a bromine number (measured according to ASTM 1159) of about 2 g Br2 / 100g to about 160 g Br2 / 100g. Such pyrolysis oils are particularly suited for the method and system according to the present invention.

[0047] More preferably, the pyrolysis oil or at least one of the pyrolysis oils in case at least two pyrolysis oils are mixed (blended) has a total acid number (TAN) in the range of from 1 mg KOH / g pyrolysis oil to about 50 mg KOH / g pyrolysis oil and / or a heating value (measured according to DIN 51900) of about 35 kJ / g to about 46 kJ / g and / or a bromine number (measured according to ASTM 1159) of about 2 g Br2 / 100g to about 160 g Br2 / 100g. Other pyrolysis oil means a pyrolysis oil which was for example manufactured as another batch and / or from another feedstock and / or with other pyrolysis reaction conditions.

[0048] A pyrolysis oil or a mixture (blend) of more than one pyrolysis oil optionally further comprises petroleum naphtha and / or bio-naphtha, such as 1 wt.-% to 99 wt.-% petroleum naphtha and / or bio-naphtha or 10 wt.-% petroleum naphtha and / or bio-naphtha or 20 wt.-% petroleum naphtha and / or bio-naphtha or 30 wt.-% petroleum naphtha and / or bionaphtha or 40 wt.-% petroleum naphtha and / or bio-naphtha or 50 wt.-% petroleum naphtha and / or bio-naphtha or 60 wt.-% petroleum naphtha and / or bio-naphtha or 70 wt.-% petroleum naphtha and / or bio-naphtha or 80 wt.-% petroleum naphtha and / or bio-naphtha or 90 wt.-% petroleum naphtha and / or bio-naphtha. The bio-naphtha itself can be a blend of bio-naphtha liquids from different sources and / or manufacturing methods.

[0049] A pyrolysis oil or a mixture (blend) of more than one pyrolysis oil optionally and / or preferably further comprise(s) for example 80 wt.-% petroleum naphtha, or 80 wt.-% petroleum naphtha and 10 wt.-% bio-naphtha and so on. The actual composition of a pyrolysis oil or a mixture (blend) of more than one pyrolysis oil together with petroleumnaphtha and / or one or more bio-naphtha liquids used is preferably guided by the available amount of pyrolysis oil(s), petroleum-naphtha, and bio-naphtha (liquids) and the respective quality which must fit the desired successive process unit such as a steam cracking unit.

[0050] Petroleum naphtha is obtained from refining of fossil sources such as crude oil and comprises hydrocarbons and has a boiling point range with an initial boiling point of about 30 °C to a final boiling point of up to about 200 °C. Petroleum naphtha can for example also be produced form other feedstocks such as coal tar, shale deposits, and tar sands.

[0051] Bio-naphtha (liquids) can be for example obtained by hydrotreatment from bio-oils. Bio-oils can be obtained for example by mechanical processes, pyrolysis, hydropyrolysis and / or hydrothermal liquefaction of renewable sources such as plant oils and / or animal fats. Such methods and the respective suitable renewable sources are known in the art.

[0052] The pyrolysis oil or mixtures (blends) as described above can be used as a feedstock for cracking such as steam cracking, thermal cracking, and catalytic cracking.

[0053] Accordingly, a cracker feedstock can comprise at least one pyrolysis oil and in addition at least one further pyrolysis oil, and / or petroleum naphtha and / or bio-naphtha (liquids).

[0054] The pyrolysis oil obtained by the pyrolysis of a feedstock as described above comprises a mixture of carboxylic acids and / or salts thereof and water. Suitable counter ions for salts of carboxylic acids are for example alkali metal cations such as Na+and K+, alkali earth metal ions such as Ca2+, ammonium ions and mixtures thereof. Preferably, the mixture of carboxylic acids and / or salts thereof in the pyrolysis oil comprises a mixture of fatty acids and / or salts thereof.

[0055] More preferably, the pyrolysis oil comprises at least one fatty acid or salt thereof selected from the group comprising saturated Cs- to C - carboxylic acids, unsaturated Cs- to C - carboxylic acids, and / or salts thereof. Suitable counter ions are for example alkali metal cations such as Na+and K+.

[0056] Most preferably, the pyrolysis oil comprises one or more of hexadecane acid, octadecene acid, tetradecane acid, dodecane acid, and octane acid and / or salts thereof.

[0057] The overall concentration of the at least one of fatty acid or salt thereof in the pyrolysis oil contributes to the total acid number (TAN) of the pyrolysis oil which ranges preferably from about 1 mg KOH / g pyrolysis oil to about 50 mg KOH / g pyrolysis oil, more preferably from about 3 mg KOH / g pyrolysis oil to about 25 mg KOH / g pyrolysis oil. The TAN is preferably determined using Test Method A in the norm ASTM D664.

[0058] The "ionic strength” of the wastewater stream a1 ' is defined herein as the concentration of cations such as for example alkali metal ions, alkali earth metal ions, ammonium ions and mixtures thereof in water. Cations such as alkali meal ions and / or alkali earth metal ions, ammonium ions and mixtures thereof which serve as a counter ion to a deprotonated carboxylic acid and / or other organic anions do not contribute to the "ionic strength” of the wastewater stream a1 ' as defined herein. They are only a contribution to the "ionic strength” when the respective deprotonated carboxylic acid and / or other organic anion is protonated, and the counter ion is released from the carboxylic acid and / or the other organic anion. Accordingly, by reducing the pH value of the wastewater stream a1 ' comprising such carboxylic acids and / or other organic anions, an increasing portion of the carboxylic acids is converted to their respective protonated form, counter ions are released from the carboxylic acids and / or other organic anions and, accordingly, the "ionic strength” of the aqueous solution a1 ' increases. Adding further salts comprising cations such as for example alkali metal ions, alkali earth metal ions, ammonium ions and mixtures thereof to the wastewater stream a1 ' likewise increases the ionic strength of the wastewater stream a1 '. The same effect occurs when reducing the pH value of the wastewater stream a1 ' and in addition adding further salts comprising cations such as for example alkali metal ions, alkali earth metal ions, ammonium ions and mixtures thereof to the wastewater stream a1 '. The solubility of the carboxylic acids and / or other organic anions in the wastewater stream a1 ' may be reduced after protonation of the carboxylic acids and / or other organic anions. A (phase) separation of the wastewater stream a1 ' into a wastewater stream a1 " and an organic waste phase o1 can be initiated by increasing the ionic strength (as defined above) of the wastewater stream a1 '. Accordingly, "increasing the ionic strength” of the wastewater stream a1 ' is one means to initiate the desired (phase separation of the wastewater stream a1 ' into a wastewater stream a1 " and an organic waste phase o1.

[0059] The total organic carbon content (TOC) is given in wt.-% and is measured as follows: First, the total carbon content (TC) is measured by combusting a sample (e.g., 1 mg to 10 mg) in a helium / oxygen atmosphere. After separation of the combustion gases, the TC is determined as CO2. The detection and quantification are made by measuring the thermal conductivity. Such a TC measurement can be made, for example, with a Vario EL Cube analyzer by Elementar Analysensysteme GmbH. Next, the total inorganic carbon content (TIC) is measured by weighting 10 mg to 100 mg of the sample into a stirred glass vessel and adding 7 ml of 25 wt.-% phosphoric acid. The resulting mixture is heated to 70 °C. A carrier gas stream of 200 ml / min N2 transports the CO2 formed to several gas-washing bottles and is then quantified in an IR measurement cell. This method was also used for examples in is also suited to obtain the total organic carbon content (TOC) TOC1 and TOC2 as set in the claims and embodiments of the present invention.

[0060] The total organic carbon content (TOC) is then calculated with the following formula:

[0061] TOC = TC - TIC

[0062] The method for reducing the total organic carbon content (TOC) of the wastewater stream a1 ' obtained from an aqueous solution a1 is suitable to reduce the total organic carbon content (TOC) in the wastewater stream a1 ' obtained after separating the aqueous solution c2 from the pyrolysis oil in a first aspect of the present invention. Next, the desired (phase) separation of the wastewater stream a1 ' into in a wastewater stream a1 " having a first volume V1 and a second total organic carbon content TOC2, and an organic waste phase o1 having a second volume V2, wherein the second total organic carbon content TOC2 is smaller than the first total organic carbon content TOC1 is initiated.

[0063] In a first aspect of the present invention, the aqueous solution b1 provided in step (I) comprises water which is formed during the pyrolysis reaction of a feedstock. This aqueous solution b1 preferably has a pH value of < 7. The aqueous solution b1 is separated from the pyrolysis oil in step (ii) of the method according to the present invention as a wastewater stream a1 '. Next, the separation of the wastewater stream a1 ' into a wastewater stream a1 " having a first volume V1 and a second total organic carbon content TOC2, and an organic waste phase o1 having a second volume V2, wherein the second total organic carbon content TOC2 is smaller than the first total organic carbon content TOC1 is initiated. The skilled person knows how to initiate a phase separation of a wastewater stream a1 ' into a wastewater stream a1 " and an organic waste phase o1 . The (phase) separation of wastewater stream a1 ' can be for example initiated by increasing the ionic strength (as defined above) of the wastewater stream a1 ' and / or other means disclosed in the specification and claims.

[0064] The aqueous solution b1 preferably having a pH value < 7 can also be used together (i.e., combined) with aqueous solution c2 formed after contacting a pyrolysis oil with an aqueous solution d in step (I) after step (ii) in a third aspect of the present invention: The (phase) separation of the wastewater stream a1 ' into a wastewater stream a1 " and an organic waste phase o1 can be for example also initiated by mixing aqueous solution b1 and aqueous solution c2 to obtain a wastewater stream a1 ' In case the (phase) separation of the wastewater stream a1 ' is not initiated by mixing aqueous solution b1 and aqueous solution c2, the desired (phase) separation can be initiated by adding

[0065] (I) at least one acidic aqueous solution to the wastewater stream a1 ' and / or (ii) adding at least one salt to the wastewater stream a1 ' until the desired separation in a wastewater stream a1 " having a first volume V1 and a second total organic carbon content TOC2, and an organic waste phase o1 having a second volume V2 is initiated.

[0066] In a second aspect of the present invention, the aqueous solution a1 is an aqueous solution c2 formed after contacting a pyrolysis oil with an aqueous solution d .

[0067] The pyrolysis oil is in the second aspect of the present invention contacted with an aqueous solution d, preferably with an aqueous solution d having an alkaline pH value, for example to adjust the pH value of the pyrolysis oil and / or to reduce the TAN or the pyrolysis oil. The pyrolysis oil is contacted with the aqueous solution d in a first containment unit, preferably a mixing unit such as an agitated vessel, a static mixer and / or with a mixing pump. The pH value of the pyrolysis oil is preferably adjusted with said aqueous solution d to a pH value in the range of about 7 to about 13, more preferably to a pH value in the range of about 9 to about 11 after said adjustment. The pH value of the pyrolysis oil after adjustment can be measured with a commercially available pH sensor (e.g., commercially available under product no. 6.0234.100 from Deutsche METROHM GmbH & Co. KG, 70794 Filderstadt, Germany). For example, a pH sensor with potassium chloride filling for measuring pH values from 0 to 14 at a temperature of 0 °C to 80 °C can be used.

[0068] The pH value of the pyrolysis oil is adjusted with an aqueous solution d to reduce the total acid number (TAN) of the pyrolysis oil to preferably about 1 mg KOH / g pyrolysis oil or less. The main contributors to the total acid number (TAN) of such pyrolysis oils are preferably organic acids. The oxygen content of pyrolysis oils which must be below certain limits depending on the later use of pyrolysis oils (e.g., as a cracker feedstock or a partial oxidation reaction feedstock). The reduction of the oxygen content in the pyrolysis oil can is preferably achieved by reducing the total acid number (TAN). In addition, by reducing the total acid number (TAN) of pyrolysis oils, the corrosive properties of such pyrolysis oils are preferably reduced.

[0069] Next, the pyrolysis oil and the aqueous solution d are separated in a liquid-liquid separation in step (II) using one or more liquid-liquid separation preferably one or more of hydrocyclone, settler tank, centrifuge, more preferably using one or more of settler tank and / or centrifuge. Thereby, a wastewater stream a1 ' having a first total organic carbon content TOC1 is obtained. Next, the (phase) separation of the wastewater stream a1 ' obtained in step (ii) is initiated (step (ill)). Thereby, the wastewater stream a1 ' separates into a wastewater stream a1 " having a first volume V1 and a second total organic carbon content TOC2, and an organic waste phase o1 having a second volume V2, wherein the second total organic carbon content TOC2 is smaller than the first total organic carbon content TOC1 .

[0070] The (phase) separation of the wastewater stream a1 ' is initiated by adding a means for initiating the desired (phase) separation. The means for initiating the (phase) separation of the wastewater phase a1 ' is selected from the group comprising acids, salts, mixing the aqueous solution b1 with aqueous solution c2, and mixtures thereof. The skilled person knows how to initiate a phase separation. The (phase) separation of wastewater stream a1 ' can be for example initiated by increasing the ionic strength (as defined above) of the wastewater stream a1 '.

[0071] The (phase) separation of the wastewater stream a1 ' can be for example initiated by adding at least one acid and / or by adding at least one salt to the wastewater stream a1 ' at least until separation of the wastewater stream a1 " having a first volume V1 and a second total organic carbon content TOC2, and an organic waste phase o1 having a second volume V2, wherein the second total organic carbon content TOC2 is smaller than the first total organic carbon content TOC1 is initiated. This is possible for all aspects of the present invention.

[0072] The at least one acid and / or the at least one salt can be added to the wastewater stream a1 ' for example in the following way: the wastewater stream a1 ' is provided in a (second) containment unit such as at least one agitated vessel, at least one static mixer, at least one mixing pump or combinations thereof and the at least one acid and / or the at least one salt is added to the wastewater stream a1 '. In case at least one acid is added to the wastewater stream a1 ', the amount of added acid(s) can be for example controlled by monitoring the pH value of the wastewater stream a1 ' and / or the change of the mass (weight) of the wastewater stream a1 ' and / or the acid(s) in a storage vessel from which the acid(s) is / are dosed into the (second) containment unit. Another method to control the amount of added acid(s) can be a visual inspection which detects the separation of the wastewater stream a1 " having a first volume V1 and a second total organic carbon content TOC2, and an organic waste phase o1 having a second volume V2, wherein the second total organic carbon content TOC2 is smaller than the first total organic carbon content TOC1, when the desired (phase) separation is initiated.

[0073] In case at least one salt is added to the wastewater stream a1 ' to initiate the desired (phase) separation, the addition can be controlled by weighting the amount of the at least one salt added and / or by weighting the wastewater stream a1 ' to which the salt is added and / or by a visual inspection which detects the separation of the wastewater stream a1 " having a first volume V1 and a second total organic carbon content TOC2, and an organic waste phase o1 having a second volume V2, wherein the second total organic carbon content TOC2 is smaller than the first total organic carbon content TOC1, when the desired (phase) separation is initiated. The at least one acid is preferably an inorganic acid and is more preferably selected from the inorganic acids comprising sulfuric acid, phosphoric acid, hydrochloric acid, nitric acid, boric acid, hydrobromic acid, perchloric acid, hydroiodic acid and mixtures thereof. "Inorganic acid” is defined herein as an acid derived from one or more inorganic compounds. "Inorganic acids” form hydrogen ions and the conjugate base when dissolved in water and tend to be very soluble in water and insoluble in organic solvents.

[0074] The at least one acid is added to the wastewater stream a1 ' until the desired (phase) separation of the wastewater stream a1 ' is initiated and separates into the wastewater stream a1 " having a first volume V1 and a second total organic carbon content TOC2, and an organic waste phase o1 having a second volume V2, wherein the second total organic carbon content TOC2 is smaller than the first total organic carbon content TOC1 . Further amounts of the at least one acid can be added to the wastewater stream a1 ' after the desired phase separation is initiated.

[0075] The amount of the at least one acid required to initiate the desired phase separation depends on various factors such as the type and concentration of the at least one acid used to initiate the desired (phase) separation and / or the pH value of the wastewater stream a1 ' before addition of said at least one acid. Further amounts of the at least one acid can be added to the wastewater stream a1 ' after the desired phase separation is initiated. The required amount of the at least one acid can be chosen by the skilled person as described in above.

[0076] The pH value of the resulting wastewater stream a1 " having a first volume V1 and a second total organic carbon content TOC2 preferably ranges from about 1 to about 10, more preferably from about 1 to about 7 and most preferably from about 1 to about 4.

[0077] The pH value of the wastewater stream a1 ' (the aqueous solution b1, the aqueous solution d, the aqueous solution c2) and the wastewater stream a1 " can be measured with a commercially available pH sensor (e.g., commercially available under product no. 6.0234.100 from Deutsche METROHM GmbH & Co. KG, 70794 Filderstadt, Germany). For example, a pH sensor with potassium chloride filling for measuring pH values from 0 to 14 at a temperature of 0 °C to 80 °C can be used.

[0078] The at least one salt is preferably selected from good soluble salts which are not toxic and poisons towards catalysts. The at least one salt is more preferably selected from the group comprising alkali metal salts, alkali earth salts, ammonium salts, and mixtures thereof, more preferably selected from the group comprising alkali metal halides, alkali metal hydrogen carbonates, alkali metal sulfates, alkali metal acetates, alkali metal formates, alkali earth halides, alkali earth hydrogen carbonates, alkali metal sulfates, alkali earth metal formates, alkali metal acetates, ammonium halides, ammonium hydrogen carbonate, ammonium sulfate, ammonium formate, ammonium acetate and mixtures thereof and most preferably selected from the group comprising sodium chloride, sodium formate, sodium acetate, potassium chloride, potassium formate, potassium acetate, ammonium chloride, ammonium formate, ammonium acetate and mixtures thereof. The formats and acetates are particularly good biodegradable. The at least one salt is added to the wastewater stream a1 ' until the separation into a wastewater stream a1 " having a first volume V1 and a second total organic carbon content TOC2, and an organic waste phase o1 having a second volume V2, wherein the second total organic carbon content TOC2 is smaller than the first total organic carbon content TOC1, starts. The amount of the at least one salt required to initiate the desired phase separation depends on various factors such as the ionic strength before addition of the at least one salt. The required amount of the at least one acid can be chosen by the skilled person as described in above.

[0079] Preferably, the amount of the at least one salt added to the wastewater stream a1 'or the total amount of salts in case more than one salt is added preferably ranges from about 0.1 wt.-% to about 30 wt.-%, more preferably from about 0.5 wt.-% to about 20 wt.-% and most preferably from about 1 .0 wt.-% to about 5 wt.-%. Further amounts of the at least one salt can be added to the wastewater stream a1 ' after the desired phase separation is initiated. The required amount of the at least one salt can be chosen by the skilled person as described in above.

[0080] The ionic strength of a wastewater stream a1 ' which is obtained from an aqueous solution c2 can also be increased in the sense of the present invention by adding another wastewater stream a1 'which is obtained from a, preferably acidic, aqueous solution b1. In case the ionic strength is not increased enough (sufficiently) to initiate the desired phase separation, additional acid(s) and / or salt(s) can be added to the wastewater stream a1 'as described above.

[0081] Optionally, solids formed in the wastewater stream a1 ' and / or the wastewater stream a1 " during and / or after step (iii) are then removed from the respective solution and / or phase. Solids are preferably removed by a method selected from the group comprising filtration, centrifugation, and combinations thereof. More preferably, solids are removed by filtration. Suitable solid separation units for removing solids from the wastewater stream a1 ' and / or the wastewater stream a1 " are selected from the group comprising filters, centrifuges, and combinations thereof.

[0082] The second containment unit used in step (iii) and the optional solid separation unit can optionally be tempered, preferably at a temperature of about 30 °C to about 200 °C, more preferably at a temperature of about 30 °C to about 120 °C and most preferably at a temperature of about 30 °C to about 80 °C.

[0083] Optionally, the method according to the present invention comprises a further step:

[0084] (iv) separating the wastewater stream a1 " having a first volume V1 and a second total organic carbon content TOC2, and the organic waste phase o1 having a second volume V2 from each other.

[0085] The wastewater stream a1 " having a first volume V1 and a second total organic carbon content TOC2, and an organic waste phase o1 having a second volume V2 are preferably separated from each other in optional step (iv) in a second liquid-liquid separation unit, the second liquid-liquid separation unit preferably using one or more of hydrocyclone, settler tank, centrifuge, more preferably using one or more of settler tank and / or centrifuge. The second total organic carbon content TOC2 in the wastewater stream a1 " preferably ranges from about 0.5 wt.-% to about 10.0 wt.-%, more preferably from about 0.5 wt.-% to about 5.0 wt.-% and most preferably from about 0.5 wt.- % to about 3.0 wt.-%.

[0086] The wastewater stream a1 " and the organic waste phase o1 are now suited for further waste treatment using conventional methods.

[0087] The method according to the present invention can be modified by optionally adding in step (iii) at least one cosolvent to the wastewater stream a1 ' to further increase the technical effect caused by initiating the desired (phase) separation of the wastewater stream a1 ' into a wastewater stream a1 " having a first volume V1 and a second total organic carbon content TOC2, and an organic waste phase o1 having a second volume V2, wherein the second total organic carbon content TOC2 is smaller than the first total organic carbon content TOC1 .

[0088] Accordingly, addition of a co-solvent or a mixture of co-solvents enhances the desired (phase) separation of the wastewater stream a1 ' into a wastewater stream a1 " having a first volume V1 and a second total organic carbon content TOC2, and an organic waste phase o1 having a second volume V2 from each other. The organic waste phase o1 then further comprises the optional co-solvent or mixture of co-solvents after the separation of the wastewater stream a1 " having a first volume V1 and a second total organic carbon content TOC2, and an organic waste phase o1 having a second volume V2.

[0089] The at least one optional co-solvent can either be a single solvent or a mixture of co-solvents.

[0090] The co-solvent or mixture of co-solvents preferably dissolves the organic components present in the wastewater stream a1 '. The co-solvent or mixture of co-solvents preferably has a low solubility in water. More preferably, the cosolvent or mixture of co-solvents has a wide miscibility gap in water of < 10%, most preferably of < 1 wt.%. Furthermore, water preferably has a low solubility in the co-solvent or mixture of co-solvents. More preferably, water has a wide miscibility gap in the co-solvent or mixture of co-solvents < 10%, most preferably of < 1 wt.%. A "miscibility gap” is defined herein as a region is a phase diagram for a mixture of components where the mixture exists in two or more phases.

[0091] The volume ratio of optional co-solvent : wastewater stream a1 ' preferably ranges from 1:200 to 2:1, more preferably from 1 :100 to 1 :1 and most preferably from 1 :100 to 1 :2.

[0092] The at least one optional co-solvent is preferably selected from the group comprising aliphatic hydrocarbons, aromatic hydrocarbons, olefinic hydrocarbons, ethers, alcohols, and mixtures thereof. Examples of suitable co-solvents comprise toluene, naphtha. Co-solvents having a low boiling point are preferred because acids dissolved in such cosolvents) can be more easily isolated from said co-solvent(s) compared to high-boiling co-solvent(s).

[0093] The at least one co-solvent preferably has a boiling point which is lower than the organic components to be removed from the wastewater stream a1 ' by the phase separation initiated by increasing the ionic strength of the wastewater stream a1 ' in step (ill). More preferably, the at least one co-solvent or mixture of co-solvents has a boiling point which is lower than the boiling point of the mixture of carboxylic acids and / or salts thereof preferably present in the wastewater stream a1 Even more preferably, the at least one co-solvent or mixture of co-solvents has a boiling point which is lower than boiling point of the at least one fatty acid and / or salt thereof preferably present in the wastewater stream a1 Most preferably, the at least one co-solvent or mixture of co-solvents has a boiling point which is lower than the boiling point of the at least one fatty acid and / or salt thereof comprising saturated Cs- to Cis carboxylic acids, unsaturated Cs- to G carboxylic acids, and / or salts thereof preferably present in the wastewater stream a1 The above-described "lower boiling point” feature enables a more economic separation of organic compounds and / or the co-solvent or mixture of co-solvents by distillation from the organic waste phase o1 and, optionally, separation of the organic compounds from the co-solvent or mixture of co-solvents.

[0094] In this case, the co-solvent is preferably again added in step (ill) to the wastewater stream a1 ' to further increase the technical effect caused by initiating the separation of the wastewater stream a1 ' into a wastewater stream a1 " having a first volume V1 and a second total organic carbon content TOC2, and an organic waste phase o1 having a second volume V2, wherein the second total organic carbon content TOC2 is smaller than the first total organic carbon content TOC1.

[0095] The optional co-solvent or mixture of co-solvents is preferably added in case the organic phase formed in step (ill) is a solid and / or has a high viscosity unsuitable for further treatment dedicated to liquid organic phases in successive waste treatment unit operations.

[0096] In a further aspect of this aspect of the present invention, the organic waste phase o1 having a second volume further comprising the optional co-solvent or mixture of co-solvents is, after separation from the wastewater stream a1 " having a first volume V1 and a second total organic carbon TOC2 in step (ill), subjected to a further separation method such as a distillation in one or more distillation columns to separate the organic waste phase o1 from the cosolvent or mixture of co-solvents. The separated co-solvent or mixture of co-solvents can then preferably re-used in step (ill) to further increase the technical effect of increasing the ionic strength of the wastewater stream a1 ' or can be used for other purposes.

[0097] Optionally, desirable organic compounds which are comprised in the wastewater stream a1 ' and then in the organic waste phase o1 having a second volume can also be separated from said organic waste phase o1 during the abovedescribed further separation method such as a distillation in one or more distillation columns. Preferably, the optional distillation after step (ill) is carried out at a temperature in the range of about 0 °C to about 600 °C, more preferably from about 20 °C to about 400 °C, most preferably from about 50 °C to about 360 °C. The corresponding operating pressure of the at least one distillation column preferably ranges from about 0.001 bar to about 4 bar (abs), more preferably from about 0.001 bar to about 0.98 bar (abs), most preferably from about 0.01 bar to about 0.05 bar (abs).

[0098] Preferably, the co-solvent or mixture of co-solvents and, optionally, desired organic compounds is / are obtained in one distillation column or in a series of distillation columns, wherein the first distillation column is for example operated at a pressure > 0.98 bar (abs) to recover low boiling components which might otherwise be difficult to recover from lower pressures. Optionally, a second distillation column is for example operated with a reduced pressure ("vacuum distillation”) to increase the yield of the components having a higher boiling point.

[0099] The method for reducing the total organic carbon of a wastewater stream obtained from the pyrolysis of a feedstock and / or from treating a pyrolysis oil with an aqueous solution can be worked in a system for reducing the total organic carbon content (TOC) of a wastewater stream obtained from the pyrolysis of a feedstock and / or treating a pyrolysis oil with an aqueous solution as described below. The described system is only one option to work the method according to the present invention. The skilled person can use other variants of said system for working the method of the invention or adapt said system accordingly.

[0100] A system for reducing the total organic carbon content of a wastewater stream obtained from the pyrolysis of a feedstock and / or from treating a pyrolysis oil with an aqueous solution, the system comprising a first containment unit, a first liquid-liquid separation unit which is downstream of and fluidically connected to the first containment unit, a second containment unit which is downstream of and fluidically connected to the first liquid-liquid separation unit, at least one dosing unit which is fluidically connected to the second containment unit, optionally, a solid separation unit which is downstream of and fluidically connected to the second containment unit, optionally a second liquid-liquid separation unit which is downstream of and fluidically connected to the second containment unit or downstream of and fluidically connected to the optional solid separation unit, wherein said at least one dosing unit utilizes pH measurement and / or mass measurement for dosing.

[0101] Said system can be used for the method for reducing the total organic carbon content of a wastewater stream obtained from the pyrolysis of a feedstock and / or from treating a pyrolysis oil with an aqueous solution according to the present invention. The system according to the present invention comprises a first containment unit which can be in principle any kind of means that can hold a volume of the pyrolysis oil and the aqueous solution a1, the aqueous solution a1 selected from the group consisting of a) aqueous solution b1 formed together with a pyrolysis oil by a pyrolysis reaction of a feedstock, b) aqueous solution c2 formed after contacting a pyrolysis oil with an aqueous solution d, wherein aqueous solutions b1 and d are different from each other.

[0102] The first containment unit is preferably selected from the group comprising agitated vessel, static mixer, mixing pump and cascade of at least two agitated vessels, more preferably selected from the group comprising, most preferably an agitated vessel in case the method according to the present invention is operated in a continuous mode.

[0103] In case the method according to the present invention is operated in a batch (-wise) mode, the first containment unit is preferably selected from vessel, agitated vessel, and combinations thereof.

[0104] The system further comprises a first liquid-liquid separation unit which is downstream of and fluidically connected to the first containment unit. The pyrolysis oil and the aqueous solution a1 are separated in the first liquid-liquid separation unit and leave the first liquid-liquid separation unit separately (through separate outlets and / or successively through one outlet).

[0105] After separation from the pyrolysis oil, the aqueous solution a1 selected from the group consisting of a) aqueous solution b1 formed together with a pyrolysis oil by a pyrolysis reaction of a feedstock, b) aqueous solution c2 formed after contacting a pyrolysis oil with an aqueous solution d, wherein aqueous solutions b1 and d are different from each other, becomes the wastewater stream a1 '.

[0106] The wastewater stream a1 ' is then inserted into a second containment unit which is downstream of and fluidically connected to the first liquid-liquid separation unit. In case the first liquid-liquid separation unit comprises separate outlets for the pyrolysis oil and the wastewater stream a1 ', the second containment unit is fluidically connected to the outlet through which the wastewater stream a1 ' leaves the first liquid-liquid separation unit. In case the first liquidliquid separation unit comprises one outlet through which the pyrolysis oil and the wastewater stream a1 ' leave the first liquid-liquid separation unit successively, the second containment unit is fluidically connected to this outlet of the first liquid-liquid separation unit.

[0107] The second containment unit is preferably selected from the group comprising agitated vessel, static mixer, mixing pump and cascade of at least two agitated vessels, more preferably selected from the group comprising agitated vessel, static mixer, mixing pump, most preferably an agitated vessel. The second containment unit has at least one inlet, preferably a first inlet which is fluidically connected to the first liquid-liquid separation unit and at least one second inlet for adding the means for initiating the desired (phase) separation of the wastewater stream a1 ' into the wastewater stream a1 " and the organic waste phase o1 . Optionally, the second inlet is also used for filling in a co-solvent or a mixture of co-solvents or an optional third inlet is used for filling in a co-solvent or a mixture of co-solvents. The co-solvent or mixture of co-solvents are an optional aspect of the method according to the present invention and is described above in detail.

[0108] The second containment unit comprises also at least one dosing unit for controlling the amount of the wastewater stream a1 ' and the means for increasing the ionic strength of the wastewater stream a1 ' filled into said at least one second containment unit. The at least one dosing unit is fluidically connected to one of the inlets of the second containment unit and / or to the second containment unit. The at least one dosing unit is pH value controlled and / or mass ratio controlled. Such dosing units are commercially available and can be applied to the system according to the present invention by a skilled person.

[0109] The means for initiating the desired (phase) separation of the wastewater stream a1 ' into the wastewater stream a1 " and the organic waste phase o1 is at least one acid and / or at least one salt, the salt either added as a solid and / or dissolved in water. In another aspect of the present invention, the wastewater stream a1 ' in which the desired (phase) separation should be increased is an aqueous solution c2 and the means for initiating the desired (phase) separation is an aqueous solution b1, preferably having an acidic pH value < 7. In case the desired (phase) separation of aqueous solution c2 is not initiated after addition of the aqueous solution b1, additionally, at least one acid and / or at least one salt, the salt either added as a solid and / or dissolved in water, is / are added to the aqueous solution c2 which was previously mixed with aqueous solution b1.

[0110] The second containment unit further comprises at least one outlet through which the wastewater stream a1 " having a first volume V1 and a second total organic carbon content TOC2, and an organic waste phase o1 having a second volume V2 and optionally a co-solvent or a mixture of co-solvents can leave the second containment unit.

[0111] Optionally, the system for reducing the total organic carbon of a wastewater stream obtained from the pyrolysis of a feedstock and / or treating a pyrolysis oil with an aqueous solution further comprises second liquid-liquid separation unit:

[0112] The at least one outlet of the second containment unit is fluidically connected to a second liquid-liquid separation unit for separating the wastewater stream a1 " and the organic waste phase o1, which organic waste phase o1 optionally further comprises a co-solvent or a mixture of co-solvents. The second liquid-liquid separation unit is a preferred part of the system in case the method according to the present invention is operated as a continuous process. The second liquid-liquid separation unit is optional in the system in case the method according to the present invention is operated as a batch process.

[0113] The wastewater stream a1 " and the organic waste phase o1 are formed in step (iii) of the method according to the present invention after the ionic strength of the wastewater stream a1 ' was increased and, optionally, a co-solvent or mixture of co-solvents was added to the wastewater stream a1 '. The optional second liquid-liquid separation unit is downstream of the second containment unit. The optional second liquid-liquid separation unit comprises at least one inlet which is fluidically connected to the at least one outlet of the second containment unit. The optional second liquid-liquid separation unit further comprises at least one outlet through which the wastewater stream a1" and the organic waste phase o1, which organic waste phase o1 optionally further comprises a co-solvent or a mixture of cosolvents can leave the optional second liquid-liquid separation unit.

[0114] Preferably, the optional second liquid-liquid separation unit comprises at least two outlets: a first outlet through which the wastewater stream a1 " can leave the optional second liquid-liquid separation unit and at least a second outlet through which the organic waste phase o1, which organic waste phase o1 optionally further comprises a co-solvent or a mixture of co-solvents can leave the optional second liquid-liquid separation unit.

[0115] The optional second liquid-liquid separation unit is preferably selected from the group comprising hydrocyclone, settler tank, and centrifuge, more preferably selected from the group comprising hydrocyclone, settler tank, and centrifuge, most preferably selected from the group comprising settler tank and centrifuge. This second liquid-liquid separation units can also be combined sequentially, e.g., a centrifuge downstream of and fluidically connected to a settler tank and so on.

[0116] The system for reducing the total organic carbon of a wastewater stream obtained from the pyrolysis of a feedstock and / or treating a pyrolysis oil with an aqueous solution optionally further comprises a further liquid-liquid separation unit, which preferably comprises one or more distillation columns to separate the organic waste phase o1 from the co-solvent or mixture of co-solvents. The optional further liquid-liquid separation unit is fluidically connected to the outlet of the optional second liquid-liquid separation unit through which the organic waste phase o1 optionally further comprising a co-solvent or a mixture of co-solvents can leave the optional second liquid-liquid separation unit. The optional further liquid-liquid separation unit is downstream of and fluidically connected to the optional second liquidliquid separation unit.

[0117] In case the system for reducing the total organic carbon of a wastewater stream obtained from the pyrolysis of a feedstock and / or from treating a pyrolysis oil with an aqueous solution optionally further comprises a further liquidliquid separation unit in which a co-solvent or a mixture of co-solvents is separated from the organic waste phase o1 , the system further comprises a fluidic connectivity between the further liquid-liquid separation unit and the optional second liquid-liquid separation unit. Thereby, the co-solvent or mixture of co-solvents separated from the organic waste phase o1 can be again added to the wastewater stream a1 ' in the second containment unit.

[0118] The converting step(s) to obtain the pyrolysis oil (embodiment 31), monomer, polymer or polymer product may comprise one or more synthesis steps and can be performed by conventional synthesis and technics well known to a person skilled in the art. Independent of the person skilled in the art to assess novelty and inventive step of the independent claim(s), the person skilled in the art to perform the converting step(s) is preferably from the technical field(s) pyrolysis, gasification, remonomerization, depolymerization, synthesis, production of monomers, polymers and polymer compounds, and / or its further processing (e.g. extrusion, injection molding). Examples of the step(s) of the conversion is / are described in "Industrial Organic Chemistry”, 3. volume, Wiley-VCH, 1997, ISBN: 978-3-527-28838-0, „Kunststoffhandbuch", 11 volumes in 17 sub-volumes, Carl Hanser Verlag; especially volume 6, ..Polyamide", 1. edition, 1966, volume 7, ..Polyurethane", 3. edition, 1993, and volume 8, "Polyester”, 1. edition 1973; "Industrial Organic Chemistry”, 3. volume, Wiley-VCH, 1997, ISBN: 978-3-527-28838-0, "Injection Molding Reference Guide, 4th edition, CreateSpace Independent Publishing Platform, 2011 , ISBN: 978-1466407824, EP0989146 (A1), EP1460094 (A1), W02006034800 (A1 ), EP 1529792 (A1), W02006042674 (A1), EP0364854 (A2), US5506275 (A), EP0897402 (A1), WO2015082316 (A1), WO2021021855 (A1), WO2021126938 (A1), W02021021902 (A1), WO2021092311 (A1), W02008155271 (A1), WO2013139827 (A1), each of which is incorporated herein by reference.

[0119] 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 method of any of embodiments 1 to 3", 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 method of any of embodiments 1 , 2 and 3". 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 the claims of the present invention.

[0120] 1. A method for reducing the total organic carbon content of a wastewater stream obtained from the pyrolysis of a feedstock and / or from treating a pyrolysis oil with an aqueous solution, the method comprising the steps

[0121] (i) providing a mixture comprising a pyrolysis oil and an aqueous solution a1 , the aqueous solution a1 selected from the group consisting of

[0122] (ia) aqueous solution b1 formed together with a pyrolysis oil by a pyrolysis reaction of a feedstock,

[0123] (ib) aqueous solution c2 formed after contacting said pyrolysis oil with an aqueous solution d,

[0124] (ii) separating the aqueous solution b1 and / or c2 from said pyrolysis oil and thereby obtain a wastewater stream a1 ', wherein the wastewater stream a1 ' has a first total organic carbon content TOC1, (iii) initiating a separation of the wastewater stream a1 ' into a wastewater stream a1 " having a first volume V1 and a second total organic carbon content TOC2, and an organic waste phase o1 having a second volume V2, wherein the second total organic carbon content TOC2 is smaller than the first total organic carbon content TOC1. Method according to embodiment 1 wherein the feedstock is selected from the group comprising or preferably consisting of plastic waste, rubber waste, bio waste and mixtures thereof. Method according to any of embodiments 1 and 2 wherein the first total organic carbon content TOC1 ranges from about 0.02 wt.-% to about 20.0 wt.-%. Method according to any of embodiments 1 to 3 wherein the pyrolysis oil has a heating value (measured according to DIN 51900) of about 35 kJ / g to about 46 kJ / g and / or a bromine number (measured according to ASTM 1159) of about 2 g Br2 / 100g to about 160 g Br2 / 100g. Method according to any of embodiments 1 to 4 wherein the pyrolysis oil has a total acid number (TAN) in the range of from 1 mg KOH / g pyrolysis oil to about 50 mg KOH / g pyrolysis oil and / or a heating value (measured according to DIN 51900) of about 35 kJ / g to about 46 kJ / g and / or a bromine number (measured according to ASTM 1159) of about 2 g Br2 / 100g to about 160 g Br2 / 100g. Method according to any of embodiments 1 to 5 wherein wastewater stream a1 ' is obtained in step (ii) by a liquid-liquid separation of the aqueous solution a1 from the pyrolysis oil. Method according to embodiment 6 wherein the aqueous solution a1 is separated from the pyrolysis oil in step (ii) by a liquid-liquid separation and the liquid-liquid separation method is selected from the group comprising separation in at least one hydrocyclone, separating in at least one settler tank, separation in at least one centrifuge, and combinations thereof. Method according to any of embodiments 1 to 7 wherein the second total organic carbon content TOC2 of the wastewater stream a1 " preferably ranges from about 0.5 wt.-% to about 10.0 wt.-%, more preferably from about 0.5 wt.-% to about 5.0 wt.-% and most preferably from about 0.5 wt.-% to about 3.0 wt.-%. Method according to any of embodiments 1 to 8 wherein the (phase) separation of the wastewater stream a1 ' is initiated by adding

[0125] (I) at least one acidic aqueous solution to aqueous solution a1 ' and / or

[0126] (ii) adding at least one salt to the aqueous solution a1 and / or

[0127] (iii) adding at least a portion of aqueous solution b1 to aqueous solution c2. Method according to any of embodiments 1 to 8 wherein the (phase) separation of the wastewater stream a1 ' is initiated by adding

[0128] (i) at least one acidic aqueous solution to aqueous solution a1 ' and

[0129] (ii) adding at least one salt to the wastewater phase to the aqueous solution a1 to aqueous solution c2. Method according to any of embodiments 1 to 8 wherein the (phase) separation of the wastewater stream a1 ' is initiated by adding

[0130] (I) at least one acidic aqueous solution to aqueous solution a1 ' and

[0131] (ii) adding at least one salt to the wastewater phase to the aqueous solution a1 and

[0132] (ill) adding at least a portion of aqueous solution b1 to aqueous solution c2. Method according to any of embodiments 1 to 8 wherein the (phase) separation of the wastewater phase a1 ' is initiated by adding

[0133] (I) at least one acidic aqueous solution to the wastewater phase a1 ' and

[0134] (ill) adding at least a portion of aqueous solution b1 to aqueous solution c2. Method according to any of embodiments 1 to 8 wherein the (phase) separation of the wastewater stream a1 ' is initiated by adding

[0135] (ii) adding at least one salt to aqueous solution a1 ' and

[0136] (ill) adding at least a portion of aqueous solution b1 to aqueous solution c2. Method according to any of embodiments 9 to 13 wherein the at least one acidic aqueous solution is selected from the group comprising sulfuric acid, phosphoric acid, hydrochloric acid, nitric acid, boric acid, hydrobromic acid, perchloric acid, hydroiodic acid and mixtures thereof. Method according to any of embodiments 1 to 14 wherein the pH value of the wastewater stream a1 " preferably ranges from about 1 to about 10, more preferably from about 1 to about 7 and most preferably from about 1 to about 4. Method according to any of embodiments 9 to 15 wherein the at least one salt is selected from the group comprising alkali metal salts, alkali earth salts, ammonium salts, and mixtures thereof. Method according to any of embodiments 9 and 16 wherein the art least one salt is selected from the group comprising alkali metal halides, alkali metal hydrogen carbonates, alkali metal sulfates, alkali metal acetates, alkali metal formates, alkali earth halides, alkali earth hydrogen carbonates, alkali metal sulfates, alkali earth metal formates, alkali metal acetates, ammonium halides, ammonium hydrogen carbonate, ammonium sulfate, ammonium formate, ammonium acetate and mixtures thereof

[0137] 18. Method according to any of embodiments 9 to 17 wherein preferably from about 0.1 wt.-% to about 30 wt.-%, more preferably from about 0.5 wt.-% to about 20 wt.-% and most preferably from about 1 .0 wt.-% to about

[0138] 5 wt.-% of the at least one salt is added to the wastewater stream a1 '.

[0139] 19. Method according to any of embodiments 1 to 18 wherein at least one co-organic solvent is added to the wastewater stream a1 ' in step (iii).

[0140] 20. Method according to any of embodiments 1 to 19 wherein at least one co-organic solvent added to the wastewater stream a1 ' in step (iii) is selected from the group comprising aliphatic hydrocarbons, aromatic hydrocarbons, olefinic hydrocarbons, ethers, alcohols, and mixtures thereof.

[0141] 21 . Method according to any of embodiments 1 to 20 wherein the volume ratio "optional co-solvent : wastewater stream a1 ' " preferably ranges from 1 :200 to 2:1 , more preferably from 1 : 100 to 1 : 1 and most preferably from 1 :100 to 1 :2.

[0142] 22. Method according to any of embodiments 1 to 21 wherein the method comprises a further step: (iv) separating the wastewater stream a1 " and the organic waste phase o1 from each other.

[0143] 23. Method according to any of embodiments 1 to 22 wherein the wastewater stream a1 " and the organic waste phase o1 are separated from each other in step (iv) by a liquid-liquid separation and the liquid-liquid separation method is selected from the group comprising separation in at least one hydrocyclone, separation in at least one settler tank, separation in at least one centrifuge, and combinations thereof.

[0144] 24. The method according to any of embodiments 1 to 23, being computer-implemented.

[0145] 25. Method according to any one of embodiments 1 to 24, comprising the step: converting the pyrolysis oil obtainable by or obtained by the method according to any one of the preceding embodiments, preferably step (ii) of the method according to any one of the preceding embodiments, or a chemical material, preferably the organic waste phase o1 , obtainable by or obtained by the method according to any one of the preceding embodiments to obtain a monomer, polymer or polymer product.

[0146] 26. Method according to embodiment 25, wherein the monomer is a di- or polyol; preferably butandiol; aldehyde; preferably formaldehyde; di- or polyisocyanate; preferably methylene diphenyl diisocyanate (MDI), polymeric methylene diphenyl diisocyanate (pMDI), toluene diisocyanate (TDI), hexamethylenediisocyanate (HDI) or isophoronediisocyanate (IPDI); amide; preferably caprolactam; alkene; preferably styrene, ethene and norbornene; alkyne, (di)ester; preferably methyl methacrylate; mono or diacid; preferably adipic acid or terephthalic acid; diamine; preferably hexamethylenediamine, nonanediamine; or sulfones; preferably 4,4'- dichlorodiphenyl sulfone.

[0147] 27. Method according to embodiment 24 or 25, wherein the polymer is and / or the polymer product comprises polyamide (PA); preferably PA 6 or PA 66; polyisocyanate polyaddition product; preferably polyurethane (PU), thermoplastic polyurethane (TPU), polyurea or polyisocyanurate (PIR); low-density polyethylene (LDPE), high- density polyethylene (HDPE), polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC), polyvinyl acetate (PVA), polystyrene (PS), poly acrylonitrile butadiene styrene (ABS), poly styrene acrylonitrile (SAN), poly acrylate styrene acrylonitrile (ASA), polytetrafluoroethylene (PTFE), poly(methyl acrylate) (PMA), poly (methyl methacrylate) (PMMA), polybutadiene (BR, PBD), poly(cis-1 ,4-isoprene), poly(trans-1,4-isoprene), polyoxymethylene (POM), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polybutylene adipate co-terephthalate (PBAT), polyester (PES), polyether sulfone (PESU), polyhydroxyalkanoate (PHA), poly-3- hydroxybutyrate (P3HB), poly-4-hydroxybutyrate (P4HB), polyhydroxyvalerate (PHV), polyhydroxyhexanoate (PHH), polyhydroxyoctanoate (PHO), polylactic acid (PLA), polysulfone (PSU), polyphenylene sulfone (PPSU), polycarbonate (PC), polyether ether ketone (PEEK), poly(p-phenylene oxide) (PPO), poly (p- phenylene ether) (PPE); or copolymer or mixture thereof.

[0148] 28. Method according to any one of embodiments 25 to 27, wherein the polymer and / or the polymer product is / are or is / are a part of: a part of a car; preferably cylinder head cover, engine cover, housing for charge air cooler, charge air cooler flap, intake pipe, intake manifold, connector, gear wheel, fan wheel, cooling water box, housing, housing part for heat exchanger, coolant cooler, charge air cooler, thermostat, water pump, radiator, fastening part, part of battery system for electromobility, dashboard, steering column switch, seat, headrest, center console, transmission component, door module, A, B, C or D pillar cover, spoiler, door handle, exterior mirror, windscreen wiper, windscreen wiper protection housing, decorative grill, cover strip, roof rail, window frame, sunroof frame, antenna panel, headlight and taillight, engine cover, cylinder head cover, intake manifold, airbag, cushion, or coating; a cloth; preferably shirt, trousers, pullover, boot, shoe, shoe sole, tight or jacket; an electrical part; preferably electrical or electronic passive or active component, circuit board, printed circuit board, housing component, foil, line, switch, plug, socket, distributor, relay, resistor, capacitor, inductor, bobbin, lamp, diode, LED, transistor, connector, regulator, integrated circuit (IC), processor, controller, memory, sensor, microswitch, microbutton, semiconductor, reflector housing for lightemitting diodes (LED), fastener for electrical or electronic component, spacer, bolt, strip, slide-in guide, screw, nut, film hinge, snap hook (snap-in), or spring tongue; a consumer, agricultural product or pharmaceutical product; preferably tennis string, climbing rope, bristle, brush, artificial grass, 3D printing filament, grass trimmer, zipper, hook and loop fastener, paper machine clothing, extrusion coating, fishing line, fishing net, offshore line and rope, vial, syringe, ampoule, bottle, sliding element, spindle nut, chain conveyor, plain bearing, roller, wheel, gear, roller, ring gear, screw and spring dampers, hose, pipeline, cable sheathing, socket, switch, cable tie, fan wheel, carpet, box or bottle for cosmetics, mattress, cushion, insulation, detergent, dishwasher tabs or powder, shampoo, body wash, shower gel, soap, fertilizer, fungicide, or pesticide; a packaging for the food industry; preferably mono- or multi-layer blown film, cast film (mono- or multilayer), biaxially stretched film, or laminating film; or a part of a construction; preferably a rotor blade, insulating material, frame, housing, wall, coating, or separating wall. Method according to any one of embodiments 25 to 28, wherein the content of the pyrolysis oil provided in step (i) in the pyrolysis oil obtainable by or obtained by the method according to any one of embodiments 1 to 24, preferably step (ii) of the method according to any one of embodiments 1 to 24, the monomer, the polymer and / or the polymer product 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 wherein the content of the pyrolysis oil provided in step (i) in the pyrolysis oil obtainable by or obtained by the method according to any one of embodiments 1 to 24, preferably step (ii) of the method according to any one of embodiments 1 to 24, the monomer, the polymer and / or the polymer product 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. System for reducing the total organic carbon content of a wastewater stream obtained from the pyrolysis of a feedstock and / or from treating a pyrolysis oil with an aqueous solution, the system comprising a first containment unit, a first liquid-liquid separation unit which is downstream of and fluidically connected to the first containment unit, a second containment unit which is downstream of and fluidically connected to the first liquid-liquid separation unit, at least one dosing unit which is fluidically connected to the second containment unit, optionally, a solid separation unit which is downstream of and fluidically connected to the second containment unit, optionally a second liquid-liquid separation unit which is downstream of and fluidically connected to the second containment unit or downstream of and fluidically connected to the optional solid separation unit, wherein said at least one dosing unit utilizes pH measurement and / or mass measurement for dosing.

[0149] 31 . Use of a system according to embodiment 30 for the method according to any of embodiments 1 to 24.

[0150] The invention will be further explained by the following non-limiting examples.

[0151] Examples

[0152] The total organic carbon content (TOC) value is given in wt.-% and is measured as follows:

[0153] First, the total carbon content (TC) value is measured by combusting a sample (e.g., 1 mg to 10 mg) in a heli- um / oxygen atmosphere. After separation of the combustion gases, the TC is determined as CO2. The detection and quantification are made by measuring the thermal conductivity. Such a TC measurement can be made, for example, with a Vario EL Cube analyzer by Elementar Analysensysteme GmbH. Next, the total inorganic carbon content (TIC) value is measured by weighting 10 mg to 100 mg of the sample into a stirred glass vessel and adding 7 ml of 25 wt.- % phosphoric acid. The resulting mixture is heated to 70 °C. A carrier gas stream of 200 ml / min N2 transports the CO2 formed to several gas-washing bottles and is then quantified in an I R measurement cell. This method is also suited to obtain the total organic carbon content (TOC) values TOC1 and TOC2 as set in the claims and embodiments of the present invention.

[0154] The total organic carbon content (TOC) is then calculated with the following formula:

[0155] TOC = TC - TIC

[0156] The pH values in the experimental section were measured with a commercially available pH sensors (e.g., available under product no. 6.0234.100 from Deutsche METROHM GmbH & Co. KG, 70794 Filderstadt, Germany). For example, a pH sensor with potassium chloride filling for measuring pH values from 0 to 14 at a temperature of 0 °C to 80 °C were used.

[0157] Example 1

[0158] A pyrolysis oil was contacted with an aqueous solution d comprising NaOH and having a pH value of 10 in an agitated vessel whereby the aqueous solution d was converted into an aqueous phase c2. The pyrolysis oil and the aqueous solution c2 were then separated from each other to obtain a wastewater stream a1 '. The wastewater stream a1 ' had a first total organic carbon content TOC1 of 9.3 wt.-% and a pH value of 10. Next, an acidic aqueous solution comprising 10 Vol.-% sulfuric acid was added to the wastewater stream a1 ' until the wastewater stream a1 ' separates into a wastewater stream a1" and an organic waste phase o1. The wastewater stream a1 " had a second total organic carbon content TOC2 of 4.0 wt.-% and a pH value of 5. Further addition of the acidic aqueous solution comprising 10 Vol.-% sulfuric acid resulted in a wastewater stream a1 " having a second total organic carbon content TOC2 of 0.95 wt.-% and a pH value of 3.

[0159] Accordingly, the total organic carbon content TOC of the aqueous solution c2 was reduced by the method according to the present invention from 9.3 wt.-% to 4.0 wt.-% and 0.95 wt.-%, respectively, in the wastewater stream a1 ",

[0160] The organic waste phase o1 comprised benzoic acid, phenol, s-caprolactam and further carboxylic acids (GC-MS measurement).

[0161] Example 2

[0162] A pyrolysis oil was contacted with an aqueous solution d comprising 25 wt.-%% KOH and having a pH value of 10 in an agitated vessel and thereby an aqueous solution c2 was obtained as wastewater stream a1 '.

[0163] Next, the wastewater stream a1 ' and the pyrolysis oil were separated from each other. The wastewater stream a1 ' had a first total organic carbon content TOC1 of 13.1 wt.-%.

[0164] The (phase) separation of the wastewater stream a1 ' was then initiated by adding an acidic aqueous solution comprising 25 Vol.-% sulfuric acid until the wastewater stream a1 ' separated into a wastewater stream a1 " and an organic waste phase o1 . The second total organic carbon content TOC2 of the wastewater stream a1 " was 1 .4 wt.-%.

[0165] Accordingly, the total organic carbon content TOC of the aqueous solution d was reduced by the method according to the present invention from 13.1 wt.-% to 1.4 wt.-% in the wastewater stream a1".

[0166] The organic waste phase o1 was solid and comprised benzoic acid, hexadecane acid and other carboxylic acids and fatty acids together with s-caprolactam (GC-MS measurement).

[0167] Example 3

[0168] Example 2 was repeated with one difference: first toluene was added to the wastewater stream a1 ' (first total organic carbon content TOC1 of 14.1 wt.-%) and then an acidic aqueous solution comprising 25 Vol.-% sulfuric acid was added to the wastewater stream a1 ' until the wastewater stream a1 ' separated into a wastewater stream a1 " and an organic waste phase o1 . The second total organic carbon content TOC2 of the wastewater stream a1 " was 0.77 wt.- %. Accordingly, the total organic carbon content TOC of the aqueous solution d was reduced by the method according to the present invention from 14 wt.-% to 0.77 wt.-% in the wastewater stream a1 " and the organic waste phase o1 was obtained in form of a liquid phase.

[0169] The organic waste phase o1 was liquid and comprised benzoic acid, hexadecane acid and other carboxylic acids and fatty acids together with s-caprolactam (GC-MS measurement). Accordingly, the liquid waste phase o1 comprised desired molecules which can be recovered from the waste stream by the method according to the present invention.

[0170] Example 4

[0171] The same type of pyrolysis oil used in Examples 2 and 3 was also used in Example 4. The pyrolysis oil was contacted with an aqueous solution d comprising 25 wt.-%% KOH and having a pH value of 10 in an agitated vessel and thereby an aqueous solution c2 was obtained as wastewater stream a1 '.

[0172] Next, the wastewater stream a1 ' and the pyrolysis oil were separated from each other. The wastewater stream a1 ' had a first total organic carbon content TOC1 of 14.8 wt.-%.

[0173] The (phase) separation of the wastewater stream a1 ' was then initiated by adding solid NaCI to the wastewater stream a1 ' until the wastewater stream a1 ' comprised 15 wt.-% NaCI and separated into a wastewater stream a1 " and an organic waste phase o1 . The second total organic carbon content TOC2 of the wastewater stream a1 " was 2.9 wt.-%.

[0174] Accordingly, the total organic carbon content TOC of the wastewater stream a1 ' was reduced by the method according to the present invention from 14.8 wt.-% to 2.9 wt.-% in the wastewater stream a1 ",

[0175] Example 5

[0176] An aqueous solution b1 (as first aqueous solution a1 ') obtained by pyrolysis of end-of-life tires was provided. The aqueous solution b1 had a pH value of 5.8 and a first total organic carbon content TOC1 of 10.5 wt.-%.

[0177] Next, the (phase) separation of the wastewater stream a1 ' was initiated by contacting the wastewater stream a1 ' with an acidic aqueous solution comprising 25 Vol.-% sulfuric acid in an agitated vessel until the wastewater stream a1 ' separated into a wastewater stream a1 " having a pH value of 1 and a solid organic waste phase o1 . The second total organic carbon content TOC2 of the wastewater stream a1 " was 5 wt.-%.

[0178] Accordingly, the total organic carbon content TOC of the wastewater stream a1 ' was reduced by the method according to the present invention from 10.5 wt.-% to 5 wt.-% in the wastewater stream a1 ".

[0179] Example 6 The same aqueous solution b1 (as first aqueous solution a1 ') was used as in example 5 which had a first total organic carbon content TOC1 of 10.5 wt.-%.

[0180] The (phase) separation of the wastewater stream a1 ' was then initiated by adding solid NaCI to the wastewater stream a1 ' until the wastewater stream a1 ' comprised 19.8 wt.-% NaCI and separated into a wastewater stream a1 " and an organic waste phase o1 . The second total organic carbon content TOC2 of the wastewater stream a1 " was 8.4 wt.-%.

[0181] Accordingly, the total organic carbon content TOC of the aqueous solution c2 was reduced by the method according to the present invention from 14.8 wt.-% to 8.4 wt.-% in the wastewater stream a1 ",

Claims

Claims1. A method for reducing the total organic carbon content of a wastewater stream obtained from the pyrolysis of a feedstock and / or from treating a pyrolysis oil with an aqueous solution, the method comprising the steps(I) providing a mixture comprising a pyrolysis oil and an aqueous solution a1, the aqueous solution a1 selected from the group consisting of(la) aqueous solution b1 formed together with said pyrolysis oil by a pyrolysis reaction of a feedstock, wherein said feedstock is selected from the group comprising plastic waste, rubber waste, bio waste and mixtures thereof,(ib) aqueous solution c2 formed after contacting said pyrolysis oil with an aqueous solution d,(ii) separating the aqueous solution b1 and / or c2 from said pyrolysis oil and thereby obtain a wastewater stream a1 ', wherein the wastewater stream a1 ' has a first total organic carbon content TOC1,(ill) initiating a separation of the wastewater stream a1 ' into a wastewater stream a1 " having a first volume V1 and a second total organic carbon content TOC2, and an organic waste phase o1 having a second volume V2, wherein the second total organic carbon content TOC2 is smaller than the first total organic carbon content TOC1 and wherein said separation is initiated in step (ill) by adding(a) at least one acidic aqueous solution to the wastewater stream a1 ' and / or(b) adding at least one salt to the wastewater stream a1 ' and / or(c) adding at least a portion of aqueous solution b1 to aqueous solution c2.

2. Method according to claim 1 wherein the feedstock is selected from the group consisting of plastic waste, rubber waste, bio waste and mixtures thereof.

3. Method according to any of claims 1 or 2 wherein the pyrolysis oil has a total acid number (TAN) in the range of from 1 mg KOH / g pyrolysis oil to about 50 mg KOH / g pyrolysis oil and / or a heating value (measured according to DIN 51900) of about 35 kJ / g to about 46 kJ / g and / or a bromine number (measured according to ASTM 1159) of about 2 g Br2 / 100g to about 160 g Br2 / 100g.

4. Method according to any of claims 1 to 3 wherein the separation of the wastewater stream a1 ' into a wastewater stream a1 " having a first volume V1 and a second total organic carbon content TOC2, and an organic waste phase o1 having a second volume V2 is initiated in step (ill) by increasing the ionic strength of the wastewater stream a1 '.

5. Method according to any one of claims 1 to 4 wherein the at least one acidic aqueous solution is selected from the group comprising sulfuric acid, phosphoric acid, hydrochloric acid, nitric acid, boric acid, hydrobromic acid, perchloric acid, hydroiodic acid and mixtures thereof.

6. Method according to any of claims 1 to 5 wherein the pH value of the wastewater stream a1 " preferably ranges from about 1 to about 10, more preferably from about 1 to about 7 and most preferably from about 1 to about 4.

7. Method according to any one of claims 1 to 6 wherein the at least one salt is selected from the group comprising alkali metal salts, alkali earth salts, ammonium salts, and mixtures thereof.

8. Method according to any of claims 1 to 7 wherein about 0.1 wt.-% to about 15 wt.-% of at least one salt is added to the wastewater phase a1 '.

9. Method according to any of claims 1 to 8 wherein the second total organic carbon content TOC2 of the wastewater phase a1 " ranges from about 0.01 wt.-% to about 5.0 wt.-%.

10. Method according to any of claims 1 to 9 wherein at least one organic solvent is added to the wastewater phase a1 ' in step (ill).11 . Method according to any of claims 1 to 10 wherein the method comprises a further step: (iv) separating the wastewater phase a1 " and the organic waste phase o1 from each other.

12. Method according to any one of the claims 1 to 11 , comprising the step: converting the pyrolysis oil obtainable by or obtained by the method according to any one of claims 1 to 11 , preferably step (II) of the method according to any one of claims 1 to 11 , or a chemical material, preferably the organic waste phase o1 , obtainable by or obtained by the method according to any one of claims 1 to 11 to obtain a monomer, polymer or polymer product.

13. Method according to claim 12, wherein the monomer is a di- or polyol; preferably butandiol; aldehyde; preferably formaldehyde; di- or polyisocyanate; preferably methylene diphenyl diisocyanate (MDI), polymeric methylene diphenyl diisocyanate (pMDI), toluene diisocyanate (TDI), hexamethylenediisocyanate (HDI) or isophoronediisocyanate (IPDI); amide; preferably caprolactam; alkene; preferably styrene, ethene and norbornene; alkyne, (di)ester; preferably methyl methacrylate; mono or diacid; preferably adipic acid or terephthalic acid; diamine; preferably hexamethylenediamine, nonanediamine; or sulfones; preferably 4,4’-dichlorodiphenyl sulfone.

14. Method according to claim 12 or 13, wherein the polymer is and / or the polymer product comprises polyamide (PA); preferably PA 6 or PA 66; polyisocyanate polyaddition product; preferably polyurethane (PU), thermoplastic polyurethane (TPU), polyurea or polyisocyanurate (PIR); low-density polyethylene (LDPE), high- density polyethylene (HDPE), polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC), polyvinyl ace-tate (PVA), polystyrene (PS), poly acrylonitrile butadiene styrene (ABS), poly styrene acrylonitrile (SAN), poly acrylate styrene acrylonitrile (ASA), polytetrafluoroethylene (PTFE), poly(methyl acrylate) (PMA), poly (methyl methacrylate) (PMMA), polybutadiene (BR, PBD), poly(cis-1 ,4-isoprene), poly(trans-1,4-isoprene), polyoxymethylene (POM), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polybutylene adipate co-terephthalate (PBAT), polyester (PES), polyether sulfone (PESU), polyhydroxyalkanoate (PHA), poly-3- hydroxybutyrate (P3HB), poly-4-hydroxybutyrate (P4HB), polyhydroxyvalerate (PHV), polyhydroxyhexanoate (PHH), polyhydroxyoctanoate (PHO), polylactic acid (PLA), polysulfone (PSU), polyphenylene sulfone (PPSU), polycarbonate (PC), polyether ether ketone (PEEK), poly(p-phenylene oxide) (PPO), poly (p- phenylene ether) (PPE); or copolymer or mixture thereof.

15. Method according to any one of claims 12 to 14, wherein the polymer and / or the polymer product is / are or is / are a part of:- a part of a car; preferably cylinder head cover, engine cover, housing for charge air cooler, charge air cooler flap, intake pipe, intake manifold, connector, gear wheel, fan wheel, cooling water box, housing, housing part for heat exchanger, coolant cooler, charge air cooler, thermostat, water pump, radiator, fastening part, part of battery system for electromobility, dashboard, steering column switch, seat, headrest, center console, transmission component, door module, A, B, C or D pillar cover, spoiler, door handle, exterior mirror, windscreen wiper, windscreen wiper protection housing, decorative grill, cover strip, roof rail, window frame, sunroof frame, antenna panel, headlight and taillight, engine cover, cylinder head cover, intake manifold, airbag, cushion, or coating;- a cloth; preferably shirt, trousers, pullover, boot, shoe, shoe sole, tight or jacket;- an electrical part; preferably electrical or electronic passive or active component, circuit board, printed circuit board, housing component, foil, line, switch, plug, socket, distributor, relay, resistor, capacitor, inductor, bobbin, lamp, diode, LED, transistor, connector, regulator, integrated circuit (IC), processor, controller, memory, sensor, microswitch, microbutton, semiconductor, reflector housing for light-emitting diodes (LED), fastener for electrical or electronic component, spacer, bolt, strip, slide-in guide, screw, nut, film hinge, snap hook (snap-in), or spring tongue;- a consumer, agricultural product or pharmaceutical product; preferably tennis string, climbing rope, bristle, brush, artificial grass, 3D printing filament, grass trimmer, zipper, hook and loop fastener, paper machine clothing, extrusion coating, fishing line, fishing net, offshore line and rope, vial, syringe, ampoule, bottle, sliding element, spindle nut, chain conveyor, plain bearing, roller, wheel, gear, roller, ring gear, screw and spring dampers, hose, pipeline, cable sheathing, socket, switch, cable tie, fan wheel, carpet, box or bottle for cosmetics, mattress, cushion, insulation, detergent, dishwasher tabs or powder, shampoo, body wash, shower gel, soap, fertilizer, fungicide, or pesticide;- a packaging for the food industry; preferably mono- or multi-layer blown film, cast film (mono- or multilayer), biaxially stretched film, or laminating film; ora part of a construction; preferably a rotor blade, insulating material, frame, housing, wall, coating, or separating wall.

16. Method according to any one of claims 12 to 15, wherein the content of the pyrolysis oil provided in step (I) in the pyrolysis oil obtainable by or obtained by the method according to any one of claims 12 to 15, preferably step (II) of the method according to any one of claims 12 to 15, the monomer, the polymer and / or the polymer product 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 wherein the content of the pyrolysis oil provided in step (I) in the pyrolysis oil obtainable by or obtained by the method according to any one of claims 12 to 15, preferably step (II) of the method according to any one of claims 12 to 15, the monomer, the polymer and / or the polymer product 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.

17. System for reducing the total organic carbon content of a wastewater stream obtained from the pyrolysis of a feedstock and / or from treating a pyrolysis oil with an aqueous solution, the system comprising- a first containment unit,- a first liquid-liquid separation unit which is downstream of and fluidically connected to the first containment unit,- a second containment unit which is downstream of and fluidically connected to the first liquid-liquid separation unit,- at least one dosing unit which is fluidically connected to the second containment unit,- optionally, a solid separation unit which is downstream of and fluidically connected to the second containment unit,- optionally a second liquid-liquid separation unit which is downstream of and fluidically connected to the second containment unit or downstream of and fluidically connected to the optional solid separation unit, wherein said at least one dosing unit which is fluidically connected to the second containment unit utilizes pH measurement and / or mass measurement for dosing.

18. Use of a system according to claim 17 for the method according to any of claims 1 to 11.