Treatment of an aqueous stream

Abstract

The present disclosure relates to a process of treating an aqueous stream from an industrial process. Specifically, the disclosed process reduces the cyanide-containing impurities and trace metal contaminants from the aqueous stream, such as to facilitate subsequent biological treatment, hydrogen gas generation by electrolysis or direct water recycle for reuse.

Description

Docket No. INV-23017-WO-PCTTREATMENT OF AN AQUEOUS STREAMCROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims the benefit of priority to U.S. Provisional Patent Application Serial No. 63 / 705,526 filed Oct. 10, 2024, the disclosure of which is incorporated herein in its entirety by reference.FIELD

[0002] This disclosure relates to a process for treating an aqueous stream from an industrial manufacturing process. Specifically, the disclosed process reduces certain undesirable impurities and metal contaminants in the aqueous streams, such as originating from a nitriles production facility, such that the aqueous stream is suitable for subsequent biotreatment, hydrogen gas generation by electrolysis or direct water recycle for reuse.BACKGROUND

[0003] Many industrial-scale processes produce wastewater containing measurable amounts of pollutants, trace metals and other fugitive impurities that are either made in the process or extracted from the metallurgy coming in contact with the process. Non-limiting examples are residual acids, bases, salts, nitriles, cyanides, metal contaminants, and other organic contaminants, etc. Examples of metal contaminants may include transition metals from the Periodic Table Groups 3 through 12, and may include iron, nickel, copper, cobalt, chromium, arsenic, cadmium, lead, antimony, mercury, and zinc. Examples of organic contaminants include dyes, phenolic compounds, surfactants, pesticides, pharmaceuticals, and microplastics.

[0004] In most cases, such wastewater effluent is collected from different parts of the process, and e.g., taken to a wastewater handing step for treatment according to the local, state and regional regulations, then disposed. Several disposal techniques are available in the industry, namely, deep-welling, incineration, bio-treatment, etc.SUMMARY

[0005] This document describes a process for treating an aqueous stream containing about 10-1000 parts per million by weight (ppmw) cyanide-containing species, about 0.5-500 ppmw metal contaminants, and about 10-10000 ppmw organic species. The process can includeDocket No. INV-23017-WO-PCT receiving this aqueous stream from an industrial system, obtaining vapor and liquid streams, cooling the vapor stream, introducing an additive to separate phases in the cooled liquid stream, concentrating the liquid stream to produce an impurity-rich liquid stream, removing the impurity-rich liquid stream by co-flowing with a flow-assist agent, and recovering a treated aqueous stream with < about 0.5 ppmw cyanide-containing species, < about 1 ppmw metal contaminants, and < about 5 ppmw organic species. The distillation system can include stripping, rectifying, concentrating, flashing, steam stripping, pump-around, side-draw, reflux, condensation, reboiler, phase separation, decantation, or combinations thereof. In an example, the additive can be a mononitrile, e.g., 2-pentenenitrile, 3 -pentenenitrile, 4-pentenenitrile, 2- methyl-2-butenenitrile, 2-methyl-3 -butenenitrile, 2-methyl-glutaronitrile, adiponitrile, 2-ethyl- succinonitrile, 2-methylene-glutaronitrile, or acrylonitrile, with cis-2-pentenenitrile. The flowassist agent can be an organic dinitrile like 2-methyl-glutaronitrile, adiponitrile, 2-ethyl- succinonitrile, 2-methylene-glutaronitrile, fumaronitrile, octanedinitrile, or decanedinitrile, with 2-methyl-glutaronitrile. The treated aqueous stream can be provided to a biological treatment facility to generate a substantially clean water stream. The impurity-rich liquid stream can include < about 10% water of its total mass. The pH of the distillation system can be maintained in a range from about 5.0 to 8.5, which can be achieved by introducing an acid such as sulfuric acid, phosphoric acid, acetic acid, carbonic acid, formic acid, hydrochloric acid, nitric acid, hydrofluoric acid, or propionic acid.BRIEF DESCRIPTION OF THE FIGURES

[0006] FIG. l is a schematic representation of an example of a fluid treatment system 100 according to the present disclosure.

[0007] FIG. 2 is a schematic representation of an example of a fluid treatment system 200 according to the present disclosure.

[0008] FIG. 3 is a flowchart illustrating a process for treatment of an aqueous stream.

[0009] FIG. 4 is a schematic representation of an example of a fluid treatment system400 according to the present disclosure.

[0010] The drawings illustrate generally, by way of example, but not by way of limitation, various embodiments discussed in the present document.Docket No. INV-23017-WO-PCTDETAILED DESCRIPTION

[0011] Reference will now be made in detail to certain aspects of the disclosed subject matter. While the disclosed subject matter will be described in conjunction with the enumerated claims, it will be understood that the exemplified subject matter is not intended to limit the claims to the disclosed subject matter.

[0012] Throughout this document, values expressed in a range format should be interpreted in a flexible manner to include not only the numerical values explicitly recited as the limits of the range, but also to include all the individual numerical values or sub-ranges encompassed within that range as if each numerical value and sub-range is explicitly recited. For example, a range of “about 0.1% to about 5%” or “about 0.1% to 5%” should be interpreted to include not just about 0.1% to about 5%, but also the individual values (e.g., 1%, 2%, 3%, and 4%) and the sub-ranges (e.g., 0.1% to 0.5%, 1.1% to 2.2%, 3.3% to 4.4%) within the indicated range. The statement “about X to Y” has the same meaning as “about X to about Y,” unless indicated otherwise. Likewise, the statement “about X, Y, or about Z” has the same meaning as “about X, about Y, or about Z,” unless indicated otherwise.

[0013] In this document, the terms “a,” “an,” or “the” are used to include one or more than one unless the context clearly dictates otherwise. The term “or” is used to refer to a nonexclusive “or” unless otherwise indicated. The statement “at least one of A and B” or “at least one of A or B” has the same meaning as “A, B, or A and B.” In addition, it is to be understood that the phraseology or terminology employed herein, and not otherwise defined, is for the purpose of description only and not of limitation. Any use of section headings is intended to aid reading of the document and is not to be interpreted as limiting; information that is relevant to a section heading may occur within or outside of that particular section.

[0014] In the processes described herein, the acts can be carried out in any order without departing from the principles of the invention, except when a temporal or operational sequence is explicitly recited. Furthermore, specified acts can be carried out concurrently unless explicit claim language recites that they be carried out separately. For example, a claimed act of doing X and a claimed act of doing Y can be conducted simultaneously within a single operation, and the resulting process will fall within the literal scope of the claimed process.

[0015] The term “about” as used herein can allow for a degree of variability in a value or range, for example, within 10%, within 5%, or within 1% of a stated value or of a stated limit of a range and includes the exact stated value or range.Docket No. INV-23017-WO-PCT

[0016] The term “substantially” as used herein refers to a majority of, or mostly, as in at least about 50%, 60%, 70%, 80%, 90%, 95%, 96%, 97%, 98%, 99%, 99.5%, 99.9%, 99.99%, or at least about 99.999% or more, or 100%. The term “substantially free of’ as used herein can mean having none or having a trivial amount of, such that the amount of material present does not affect the material properties of the composition including the material, such that the composition is about 0 wt% to about 5 wt% of the material, or about 0 wt% to about 1 wt%, or about 5 wt% or less, or less than, equal to, or greater than about 4.5 wt%, 4, 3.5, 3, 2.5, 2, 1.5, 1, 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.3, 0.2, 0.1, 0.01, or about 0.001 wt% or less. The term “substantially free of’ can mean having a trivial amount of, such that a composition is about 0 wt% to about 5 wt% of the material, or about 0 wt% to about 1 wt%, or about 5 wt% or less, or less than, equal to, or greater than about 4.5 wt%, 4, 3.5, 3, 2.5, 2, 1.5, 1, 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.3, 0.2, 0.1, 0.01, or about 0.001 wt% or less, or about 0 wt%.

[0017] It is understood that the descriptions herein are intended to be illustrative, and not restrictive. Many other embodiments will be apparent to those of skill in the art upon reviewing the above description. The scope of the invention should, therefore, be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled. In the appended claims, the terms “including” and “in which” are used as the plain-English equivalents of the respective terms “comprising” and “wherein,” respectively. Moreover, the terms “first,” “second,” “third,” and the like are used merely as labels, and are not intended to impose numerical requirements on their objects.

[0018] Sizeable aqueous streams may be generated during certain nitriles and cyanides manufacturing processes. For example, such manufacturing processes can include HCN synthesis, butadiene hydrocyanation to dinitriles, alcohol ammoxidation to cyanides (HCN, acetonitrile), propane / propylene ammoxidation to acrylonitrile, coupling of acrylonitrile to dinitriles, or cyanohydrin synthesis. Certain industrial-scale processes can involve a stoichiometric excess ammonia feed, such as to facilitate recovery and resource conservation.

[0019] Certain ammonia recovery steps can generate relatively large amounts of aqueous streams. One challenge involved in recycling of such aqueous streams is they may contain significant levels of cyanides, organics, and nitriles impurities. Such streams can also contain certain detectable metal elements originating from equipment metallurgy and catalyst materials. Components that may be present in such aqueous streams can include, e.g., free cyanides and nitriles, cyanide ions, iron, chromium, cobalt, or phosphates.

[0020] In one approach to purification of an aqueous stream, an ammonia enricherDocket No. INV-23017-WO-PCT column tails stream can include an aqueous stream containing about 100-500 ppm cyanides and other trace contaminants such as phosphates, iron, nickel, chromium, or cobalt. Such contaminated aqueous streams can be unsuitable for reusable water recovery and certain treatments, such as bio-treatment via biological mass.

[0021] One approach to disposing of such aqueous streams involves incineration. However, incinerating such dilute water-containing streams can involve a significant amount of energy, and thus, can be unfeasible in certain circumstances or at certain desired scales. Another approach can involve deep-well injection of such streams. However, such an approach can be challenging in that it is not always feasible to perform onsite in certain locations. Further, storing, handling, and transporting such streams can involve significant challenges limiting the practicality of such approaches.

[0022] The present inventors have recognized the benefits of addressing aqueous waste stream disposal in a cost efficient and practical manner, such as involving a distillation system and using additives to effect phase separation of components in the stream.

[0023] FIG. 1 schematically represents a fluid treatment system 100. The system 100 can include various components, such as flowline valves, fittings, thermocouples, pressure gauges, flow measurement devices, relief valves, drains, and analyti cal / control instrumentation. In FIG. 1, a stream 101 can include a feed that can originate from, e.g., a process plant containing nitriles, cyanides, and metal constituents. A composition of stream 101 can vary, such as depending on the source of the aqueous stream, e.g., whether received from a clean-up stream, a floor drain, a wash, or a combination thereof. In an example, the stream 101 may be collected from a hydrogen cyanide (HCN) production facility. In an example, the stream 101 may be gathered from a nitrile or diamine facility and combined as an aqueous stream. In an example, stream 101 may originate from runoff of an equipment cleanup apparatus or system, such as involving a caustic solution for cleaning equipment.

[0024] In an example, stream 101 can be mixed with a recycle stream 137, and the resulting combined feed stream 101 A can be fed toward a first column 110. The recycle stream 137 can comprising mostly water including certain nitriles or lighter hydrocarbon species. For example, an upper portion of column 110 can receive a plurality of recycle aqueous streams for balancing or maintaining desired column hydraulics, such as stream 123 and stream 127 as depicted in FIG. 1. Stream 123 can include a split-stream received or obtained from a separator 130, e.g., including a three-phase separator / decanter, while stream 127 can be received or obtained from a third column 160. The first column 110 can include a base reboiler configuredDocket No. INV-23017-WO-PCT to boil the combined feed stream 101 A and provide vapor traffic within the first column 110. The down-flowing liquid in the first column 110 can transport the organic and nitrile species from the up-flowing vapor and can facilitate concentration of the organic and nitrile species at a lower portion of the first column 110. Here, the organic and nitrile species can exit lower portion of the first column 110 via a bottoms stream 111. In an example, a liquid side-stream 105 can exit the upper portion of column HOvia a pump unit 140. At least a portion of the side-stream 105 can be recirculated (e.g., at 109) back through the first column 110, such as below a side-draw take-off, while the remaining liquid can proceed toward a second column 150, establishing a stream 107.

[0025] The second column 150 can include or use a reboiler, e.g., located at or a base of the second column 150. In an example, the second column 150 can be operated at specified conditions to promote for stripping any cyanide species present in the entering stream 107. For example, stripping of the cyanide species can be achieved by establishing a higher boiling temperature of water and other liquid removal from the liquid stream with the presence of certain finish, e.g., lowering or raised pH, strong base, or other reacting material in a sidestream entering the second column 150. In an example, the stream 115 can exit a lower portion of the second column 150. The overhead vapor stream 113 can include water exhibiting elevated levels of cyanides and organic impurities, relative to levels of cyanides and organic impurities exhibited by the stream 115.

[0026] In an example, respective vapor streams exiting the first column 110 and the second column 150 overhead vapor streams can be combined and cooled in a heat exchanger 120. The cooled stream 117 can be fed to the separator 130 wherein, phase splitting followed by phase separation and decantation can be facilitated. The separator 130 can include light / heavy phase separation internals and vapor-liquid disengagement / demister sections.

[0027] A nitrile co-product stream 119 can additionally be introduced to separator 130. The nitrile co-product stream 119 can help facilitate phase splitting and concentrating the organic, cyanide and nitrile impurities in a light (e.g., organic) phase versus a heavier (e.g., water-rich) phase. For example, the cooled stream 117 can effectively be partitioned into an organic stream 143 and an aqueous stream 121. In an example, a small overhead vaporous stream 145 from the separator 130 can include certain non-condensable components, e.g., nitrogen, lighter organics, and residual nitriles. In an example, the vapor stream 145 can be subsequently routed toward a gas header for disposal.Docket No. INV-23017-WO-PCT

[0028] At least portion of the aqueous stream 121 from the separator 130 can be routed back toward the top portion of the first column 110, e.g., via a stream 123. The remaining liquid can be fed forward toward the third column 160, via a stream 121 A. In an example, a steady stream of inert gas stream 125 can be sparged, e.g., at or near a base of the third column 160, such as to facilitate stripping the organic and nitrile impurities from the down-flowing liquid. A resulting bottom stream 127 can be routed back toward the first column 110. The overhead vapor stream 129 can be withdrawn from the third column 160 and can be routed toward a gas header, such as for disposal.

[0029] In an example, a bottoms stream 111 exiting the first column 110 can flow toward a vacuum flash unit 170. The conditions in the vacuum flash unit 170 can be established or maintained such that a majority of organic and nitrile impurities concentrate at the bottom and are withdrawn as stream 135. This stream can also contain fugitive trace metals, such as present in readily measurable concentrations. A stream 135 can be routed toward a thermal destruction facility such as an incinerator. For example, a flow-assist stream 131 can be fed to unit 170 to promote a flowability of stream 135.

[0030] A stripped vapor stream 133 can exit the vacuum flash unit 170 and can be fed toward a vapor-liquid separator unit 180. Certain parameters (e.g., temperature, pressure, etc.) of the vapor-liquid separator unit 180 can be maintained such that the non-condensable stream 139 is separated from the liquid. A stream 139 can be routed toward a gas header, e.g., for further treatment such as via a scrubber or flare unit. A liquid stream 137, e.g., containing any residual impurities, can be routed back toward column 110 for recirculation and further purifaction.

[0031] The disclosed process has wide industrial applicability. For example, an industrial acrylonitrile manufacturing facility can generate a large quantity of a cyanide- containing and trace metal contaminated wastewater stream. The disclosed process is effective in cleaning up this stream with impurity levels tolerable by bio-treatment such as where other approaches are unfeasible. The clean water stream can be suitable for recycle / reuse back in the process helping the water conservation target. In an example, a hydrogen cyanide manufacturing facility can generate a wastewater stream with high levels of cyanide-containing impurities that can be undesirable for exposure to the biological mass in the bio-treatment step. The disclosed process may be applied such as to treat the wastewater and the cyanide- containing impurities reduced to the levels that are not harmful anymore for the bio-treatment step. The clean water from the bio-treatment step can be available for recycle / reuse. In oneDocket No. INV-23017-WO-PCT example, the clean water stream obtained from the disclosed process can be fed to an electrolysis process for generating hydrogen gas.EXAMPLES

[0032] Various aspects of the present disclosure can be better understood by reference to the following Examples which are offered by way of illustration. The present disclosure is not limited to the Examples given herein.

[0033] The term “substantially clean water stream”, as used herein, is defined as the water stream having at least 99.99% purity and containing <0.5 parts per million by weight (ppmw) cyanide impurities, <1 ppmw metal impurities and <5 ppmw other organic impurities.

[0034] The term “organic species” or “organic impurities”, as used herein, refers to hydrocarbon and other common industrial compounds that may be present in a stream. Some common examples may include benzene, cyclohexane, phenols, cresols, Ci-Cs mononitriles and Cs-Cs dinitriles.Example 1

[0035] The fluid treatment system 100, as described above and schematically represented in FIG. 1, is employed in this example.

[0036] Tables 1-3 provide stream mass flowrates, temperatures, pressures and mass liquid / vapor fractions, and correspond to those schematically represented in FIG. 1.

[0037] In Tables 1-3, the term “C6 Organics” may include six-carbon light organic impurities such as cyclohexane, benzene, etc.

[0038] In Table 1-3, the term “Light Organics” may include light organic impurities such as phenols and cresols, etc.

[0039] In Table 1-3, the term “Low-boiling Nitriles” may include low boiling point mono- and dinitrile components from a nitriles manufacturing process. These may include acetonitrile, acrylonitrile, ethanenitrile, propanenitrile, butanenitrile, 2-pentenenitrile, 3- pentenenitrile (3PN), 4-pentenenitrile (4PN), 2-methyl-2-butenenitrile (2M2BN), 2-methyl-3- butenenitrile (2M3BN), valeronitrile (VN), benzonitrile, butyronitrile, isobutyronitrile, fumaronitrile, etc. The aqueous streams from the nitriles plant facility may contain fugitive levels of these cyano-containing impurities.

[0040] In Table 1-3, the term “High-boiling dinitriles” may include high boiling point dinitrile components from a nitriles manufacturing process that have boiling points more thanDocket No. INV-23017-WO-PCT200 °C. These may include 2-methylgluratonitrile (MGN), 2-methyleneglutaronitrile adiponitrile (ADN), octanedinitrile, decanedinitrile, 2-ethyl succinonitrile (ESN), naphtonitrile, tolunitrile etc. The aqueous streams from the nitriles plant facility may contain fugitive levels of these cyano-containing impurities.

[0041] Table 1Docket No. INV-23017-WO-PCT

[0042] Table 2Docket No. INV-23017-WO-PCT

[0044] Table 3

[0045] In the fluid treatment system 100, the stream 101 is >99 % (by wt.) water and contains <1% of the combined high-boiling nitriles, low-boiling nitriles, residual lighter organics, cyanides and ammoniacal species. Here, the stream 101 is unsuitable for a desired approach to bio-treatment, therefore, is not immediately fed to a bio-processing facility. Optionally, the stream 101 is unsuitable for its direct use as water recycle and reuse.

[0046] The stream 101 is mixed with the recycle stream 137, and the combined feed stream 101 A is fed to the first column 110. The recycle stream 137 is mostly water wherein the nitriles and lighter hydrocarbon species are concentrated to about 8 wt%. The recycle stream 137 is relatively small, amounting to less than 5% of stream 101. In the present example, a ratio of stream 137 : stream 101 is about 2.5% (by mass).

[0047] The top portion of the first column 110 receives two recycle aqueous streams, namely, about 1,225 kg / hr of the stream 123 and about 740 kg / hr of the stream 127. The first column 110 includes the base reboiler configured to boil the feed and provide up-flowing vaporDocket No. INV-23017-WO-PCT traffic in the first column 110. The down-flowing liquid in column 110 transports the organic and nitrile species from the up-flowing vapor and concentrates them at or near a base of the first column 110. The organic and nitrile species exit the first column 110 via the bottoms stream 111, which is about 18-20 % (by wt.) organics and nitriles, balance water. The liquid side-stream 105 is pumped out from the upper section of the first column 110 via the pump 140. In this example a small portion (~ 5%) of side-stream 105 is returned back to the first column 110 below the side take-off, while the remaining liquid is fed forward to the second column 150 as the stream 107. Here, the liquid load below side-draw in column 110 is controlled by the column reboiler duty.

[0048] The second column 150 is equipped with a reboiler at the base and is operated at the conditions that are desirable for stripping the cyanide species present in stream 107. Here, greater than 90% of the entering feed is discharged from the second column 150 as the stream 115, and the stream 115 contains <1 parts per million by weight (ppmw) cyanides and <700 ppmw residual organic impurities. The overhead vapor stream 113 consists mainly of water including elevated levels of the cyanides and organic impurities.

[0049] Respective vapor streams of the first column 110 and the second column 150 overhead are combined and cooled in the heat exchanger 120 to 40-60 °C range. The cooled stream 117 is fed to the separator 130, including a three-phase separator / decanter.

[0050] A relatively small nitrile co-product stream 119, rich in 2-pentenenitrile (2PN), is introduced to the separator 130. With the addition of the stream 119 to the separator 130, the stream 117 is effectively partitioned into stream 143 (organic phase) and stream 121 (aqueous phase). The overhead vaporous stream 145 from the separator 130 includes noncondensable components such as nitrogen, lighter organics and residual nitriles. Subsequently, the vapor stream 145 can be routed to a gas header for post-process disposal.

[0051] The relatively heavy, aqueous stream 121, obtained from the separator 130, is split into two portions, about two-thirds as stream 123 and about one-thirds as stream 121A. The stream 123 is routed back to the top section of the first column 110, while the stream 121 A is fed forward to the third column 160. A steady stream of the inert gas stream 125 is sparged at the base of the third column 160 to strip the organic and nitrile impurities from the downflowing liquid. The bottom stream 127 is mostly 99.99 wt% water with trace levels of impurities. The stream 127 is pumped back to the first column 110 to supplement the separation in the first column 110. The overhead vapor stream 129, comprised mainly of 2PN,Docket No. INV-23017-WO-PCT organics and residual cyanides, ammonia, etc., exits the third column 160, and can be subsequently routed toward a gas header for disposal.

[0052] The bottoms stream 111 from the first column 110 flows to the vacuum flash unit 170 operating at 110 °C and about 5.8 Psia (or 300 mmHg). The conditions in the vacuum flash unit 170 are maintained such that the majority of organic and nitrile impurities are concentrated at the bottom and discharged as stream 135. Stream 135 is less than 0.5 % (by mass) of stream 101. However, it is concentrated with the organic, nitrile, cyanide and trace metal impurities, desired to be removed from the stream 101. This concentrated organic stream 135, containing more than 90 wt.% impurities, can ease a disposal process.

[0053] It can be challenging to flow the concentrated stream 135 without the stream 135 thickening upon cooling. In the present example, a relatively small flow-assist stream 131 can be provided to overcome this challenge and to help facilitate a flowability of the stream 135. Although there is no restriction on the amount of the stream 131 used, mass ratios of about 45 : 1 for stream 111 : stream 131 can be preferred in the present example. In this example, the readily available co-product, crude 2-methylglutaronitrile (MGN), from a dinitrile production facility is used for the stream 131. The crude MGN may contain about 10-15% 2- ethylsuccinonitrile (ESN) and about 3-5% adiponitrile (ADN). However, there is no restriction against using other kinds of flow-assist agents such that they are chemically compatible with the components present in the stream 111 and with the appropriate equipment metallurgy. Examples of other nitriles that can be incorporated in the flow assist stream 131 include 2- methyleneglutaronitrile, 2-ethyl succinonitrile, acrylonitrile, fumaronitrile, octanedinitrile, and decanedinitrile.

[0054] The stripped vapor stream 133, obtained from the vacuum flash unit 170, is fed to the vapor-liquid separator 180. The separator 180 conditions are maintained such that the non-condensable stream 139 is separated from the liquid. The stream 139 may be routed to a gas header for subsequent treatment, for example, a scrubber or flare unit. The liquid stream 137, containing the residual impurities, is recirculated through the first column 110 for additional purification.

[0055] In this example, the disclosed apparatus desirably removes various impurities from the stream 101 down to the trace levels in the stream 115. These impurities include cyanides, ammoniacal species, C6 Organics, Light Organics, Low-boiling, high-boiling Dinitriles and trace metals. The stream 115 can be fed to a bio-treatment step without posingDocket No. INV-23017-WO-PCT any threat to the bio-mass health. The bio-treated aqueous stream is sufficiently clean to be reused and recycled to meet the site water conservation goal.

[0056] It may be feasible to take either the entire stream 115 or a portion of stream 115 for clean water recycle in the apparatus, thereby meeting the goal of water conservation for the site. For example, stream 115 is sufficiently clean to be used in a quench column, water absorption column system, cooling systems, as boiler feed water, for dilution and other practical applications where clean water is needed. In one non-limiting example, about 10-20 % of the stream 115 can be routed to the quench system as clean water for quenching. In another example, about 50% of the stream 115 can be taken for cooling and condenser operations.

[0057] In this example, and according to this disclosure, more than 374thof the C6 Organics components in stream 101 are concentrated in liquid stream 143 (organic phase), and the rest may end up in overhead vaporous stream 145. Both these streams may be routed for proper disposal. Optionally, the C6 Organics concentrated stream 143 can be recycled back to improve the useful atomic yield recovery efficiency.

[0058] In this example, and according to this disclosure, over 90% of the Light Organics components in stream 101 are concentrated in stream 135, which is routed for proper disposal, incineration for example. Optionally, the Light Organics concentrated stream 135 can be recycled to improve the useful atomic yield recovery efficiency.

[0059] In this example, according to this disclosure, the majority of Low-boiling Nitriles components in stream 101 are concentrated in stream 129, which is routed for proper disposal.

[0060] In this example, and according to this disclosure, the majority of High-boiling dinitriles components in stream 101 are concentrated in stream 135, which is routed for disposal. Optionally, the high-boiling dinitriles concentrated stream 135 can be recycled to improve the useful atomic yield recovery efficiency. In this example, the stream 135 containing higher than 80 wt% of some useful nitriles and dinitriles can be recycled back to a nitriles recovery step.Examples 2a-2g

[0061] In each example about 45 ml of an aqueous stream originating from an industrial HCN synthesis facility was put in a stirred flash and maintained at a desired temperature. About 14-18 std. cc / min (or seem) of nitrogen was bubbled through the liquid to simulateDocket No. INV-23017-WO-PCT stripping of a cyanide impurity from the solution. The stirring speed was 750 RPM. An acid was added to each run sample to lower the pH to 5.5 before the test. Suitable acids for pH lowering may include sulfuric acid, phosphoric acid, acetic acid, carbonic acid, formic acid, hydrochloric acid, nitric acid, hydrofluoric acid, propionic acid, oxalic acid, etc.

[0062] Table 4 below illustrates the observed cyanides removal from the test samples.

[0063] Table 4*parts per million by weight (abbreviated as ppmw);

[0064] The final cyanide [CN‘] levels of <0.05 ppmw could be achieved in Examples 2f and 2g of Table 4. The pH reduction from 8.0 to 6.5, as in Example 2g, unexpectedly resulted in very low levels of the final cyanide [CN‘] in the tested sample. A separate example, similar to the Example 2g conditions, was run except the starting pH of the aqueous test sample was 10. This run did not achieve any reduction of the cyanide [CN‘] level. However, the cyanide reduction was achieved when the pH was lowered to 8.0.Example 3

[0065] FIG. 2 is a schematic representation of an example of a fluid treatment system 200 according to the present disclosure.

[0066] A column 250 is equipped with a plurality (e.g., about 13theoretical) stages for the removal of cyanides present in stream 251, which is fed to the column 250 at or near a top portion of the column 250. Here, the stream 251 is an aqueous stream originating from an HCN facility, has a pH of about 8.7, and contains about 40 ppmw HCN and <100 ppmw ammonia in the dissolved state. A reboiler included in the column 250 base provides the boil- up energy and vapor up-flow effective to strip cyanides from the down-flowing liquid.Docket No. INV-23017-WO-PCT

[0067] Table 5

[0068] The dissolved cyanide [CN‘] and ammonia are stripped and concentrated in the overhead vapor stream 253. A relatively small N2 bleed 257 is added to stream 253, and the resultant vapor stream 259 is routed to a gas header for proper disposal. The stripped aqueous stream 255 is discharged from the column 250 and is cooled to about 20-25 °C for further use. Stream 255 contains <50 ppmw ammonia and <0.1 ppmw cyanides [CN‘] which may be further bio-treated. The feed stream 251, by itself, is undesirable for bio-treatment due to the high cyanide levels.Example 4

[0069] An aqueous caustic wash is typically employed for equipment clean-up in an industrial HCN production facility. The spent aqueous wash stream with a pH of ~12 may contain as much as 10-1000 ppmw cyanides [for example, sodium cyanide; NaCN] and fugitive metals.

[0070] A scheme, similar to the the fluid treatment system 100 of FIG. 1, is used for the removal of contaminants from the above stream (equivalent to feed stream 101 in FIG. 1). A small amount of acid, for example, sulfuric acid, is added to this stream to neutralize the caustic component, thereby, lowering the pH from 12 to <8. The conditions are similar to those detailed in Example 1, except the stream 121A to the third column 160 is increased. The stripped aqueous stream 115 contains <0.5 ppmw cyanides. Stream 135 obtained from unit 170 contains concentrated organic, nitrile, cyanide and trace metal impurities. TheDocket No. INV-23017-WO-PCT concentrated organic stream 135, containing less than 5 wt.% water, is routed to a thermal destruction facility such as an incinerator. A small flow-assist stream 131, such as a crude nitriles co-product, is fed to unit 170 to improve the flowability of stream 135.

[0071] As an illustration, about 5,000 kgs of the collected aqueous caustic wash stream is fed to the disclosed apparatus, shown in FIG. 1, at the rate of about 150 kg / hr as feed stream 101 over a period of less than two days. The apparatus generates an aqueous stream [i.e., stream 115] with much reduced impurities and is suitable for biotreatment. Optionally, the stream 115 of this example can be used for direct water recycle and reuse. The concentrated stream 135 amounts to less than 0.5 % of the feed quantity which can be sent for incineration.

[0072] Using the disclosed apparatus, the aqueous caustic wash stream may be cleaned up to be suitable for the bio-treatment step. Upon bio-treatment the resulting aqueous stream 115 is available for recycle / reuse to meet the site water conservation goal. It is much more practical and cost-effective to incinerate small concentrated stream 135 instead of the entire 5,000 kgs of aqueous caustic wash stream.Example 5

[0073] The entire 5,000 kgs of aqueous caustic wash stream, described in Example 4, is disposed via incineration. The storage, handling, transportation and incineration costs are significant. In addition, it is very energy intensive to incinerate this mostly water-diluted waste stream. Upon incineration there can be much less than a desired amount of reusable water stream available to facilitate desired water conservation.Example 6

[0074] A scheme, similar to a fluid treatment system 100 of FIG. 1, is used except the cis-2PN rich stream 119 is not introduced to the separator / decanter unit 130. It is unexpectedly observed that the organic-aqueous phase splitting followed by their separation in the unit 130 is inconsistent which results in phase interface control difficulties. The undesirable impurities can not be substantially concentrated in any single stream to be able to purge via streams 143 and 145.

[0075] This example can involve inadequate removal certain various impurities from stream 101 down to the trace levels compared to stream 115 of Example 1. Stream 115 of this example can be unsuitable for certain approaches to bio-treatment. The water conservation by recovery and recycle can not be feasible in this example.Docket No. INV-23017-WO-PCTExample 7

[0076] A device, similar to the fluid treatment system 100 in FIG. 1, is used except the flow-assist stream 131, such as a crude nitriles co-product, is not fed to unit 170. It is difficult to remove stream 135 from unit 170 due to its thickened flow rheology. The overall process is not continued as the constituents present in stream 135 begin to accumulate in unit 170. As the undesirable impurities begin to build-up in units 110, 130, 150, 160, 170, 180, and streams 123, 127, 133 and 137, this example can be inadequate, in certain conditions, for desired removal of impurities to yield a cleaner stream 115 as observed in Example 1. Stream 115 of this example remains unsuitable for bio-treatment due to the elevated impurity levels, mainly the cyanides and trace metals. The water conservation by recovery and recycle can not be feasible in this example.Example 8

[0077] An industrial adiponitrile manufacturing facility generates several aqueous waste streams, for example, an aqueous waste stream generated from the HCN production step, and another waste stream generated from the nitriles recovery / separation step. It can be desirable to treat these aqueous streams to achieve two goals: i) treat the aqueous waste streams to reduce the contaminants and metal impurities below the site discharge limits; and 2) obtain a clean water stream that can be re-used in the facility for the site water conservation.

[0078] The above-mentioned aqueous waste streams can have as much as 10-50 ppmw total cyanides and fugitive metals above the site discharge limits that are, typically, less than 1 ppmw.

[0079] FIG. 3 is a flowchart illustrating an apparatus for treatment of an aqueous stream.

[0080] At 310, an aqueous stream can be received or accessed, such as from an industrial apparatus. This aqueous stream can contain, e.g., between about 10-1000 parts per million by weight (ppmw) of cyanide-containing species, between about 0.5-500 ppmw of metal contaminants, between about 10-10000 ppmw of organic species, or a combination thereof.

[0081] At 320 a vapor stream and a liquid stream can be provided or obtained from the distillation system. The distillation system may include various components such as stripping, rectifying, concentrating, flashing, steam stripping, pump-around, side-draw, reflux,Docket No. INV-23017-WO-PCT condensation, reboiler, phase separation, and decantation units, or combinations thereof. For example, such components can help facilitate effective separation and purification of the aqueous stream. In an example, the vapor stream can be cooled such as to obtain a cooled liquid stream. This cooling step may be performed using heat exchangers or other suitable cooling equipment.

[0082] At 330, an additive can be introduced to the cooled liquid stream such as to separate a phase of the cooled liquid stream. This additive can be, e.g., a mononitrile. For example, the mononitrile can be cis-2-pentenenitrile, which can be particularly effective. Other suitable organic nitriles that can be used include 2-pentenenitrile, 3 -pentenenitrile, 4- pentenenitrile, 2-methyl-2 -butenenitrile, 2-methyl-3 -butenenitrile, 2-methyl-glutaronitrile, adiponitrile, 2-ethyl-succinonitrile, 2-methylene-glutaronitrile, or acrylonitrile. The choice of additive can be optimized based on the specific composition of the aqueous stream and the desired separation efficiency.

[0083] At 340, the liquid stream can be concentrated such as to produce an impurityrich liquid stream. Such concentration can involve further distillation or other separation techniques. In an example, the impurity-rich liquid stream typically comprises <10% water of its total mass, indicating a high concentration of impurities. For example, the impurity-rich liquid stream can then be removed by co-flowing with a flow-assist agent. The flow-assist agent may be an organic dinitrile, such as 2-methyl-glutaronitrile, which has shown particular effectiveness. Other suitable dinitriles that can be used include adiponitrile, 2-ethyl- succinonitrile, acrylonitrile, 2-methylene-glutaronitrile, fumaronitrile, octanedinitrile, or decanedinitrile. The choice of flow-assist agent can be tailored to the specific impurities present and the desired removal efficiency.

[0084] At 350, the treated aqueous stream can be recovered. This treated stream can exhibit significantly reduced levels of contaminants, specifically < about 0.5 ppmw cyanide- containing species, < about 1 ppmw metal contaminants, < about 5 ppmw organic species, or a combination thereof.

[0085] In an example, the pH of the distillation system can be established or maintained within a range from 5.0 to 8.5. This pH control can help facilitate separation and purification apparatuses. The pH adjustment can be achieved such as by introducing an acid to the system as needed. Suitable acids for this purpose include sulfuric acid, phosphoric acid, acetic acid, carbonic acid, formic acid, hydrochloric acid, nitric acid, hydrofluoric acid, or propionic acid.Docket No. INV-23017-WO-PCTThe choice of acid and the precise pH target within the specified range can be adjusted based on the specific contaminants present and the desired purification efficiency.

[0086] The resulting treated aqueous stream, with its significantly reduced contaminant levels, may be further provided to a biological treatment facility to generate a substantially clean water stream suitable for reuse or discharge. This additional biological treatment step can further enhance the purity of the water, making it suitable for a wide range of applications or safe environmental release.

[0087] Optionally, the resulting treated aqueous stream, with its significantly reduced contaminant levels, may be further provided as direct clean water recycle for reuse. Such steps as the quench, cooling, steam generation, cooling tower operations, hydrogen gas generation by electrolysis can utilize this clean aqueous stream.

[0088] The disclosed apparatus can provide an efficient and effective method for treating aqueous streams containing cyanide-containing species, metal contaminants, and organic species, resulting in a high-quality treated water stream while concentrating impurities for easier disposal or further treatment.Example 9

[0089] FIG. 4 is a schematic representation of an example of a fluid treatment system 400 according to the present disclosure.

[0090] Tables 6-8 provide the stream mass flowrates, temperatures, pressures and mass liquid / vapor fractions for the disclosed apparatus, and correspond to those schematically represented in FIG. 4.

[0091] In Tables 6-8, the terms “C6 Organics”, “Light Organics”, “Low-boiling Nitriles” and “High-boiling dinitriles” have been described in Example 1.Docket No. INV-23017-WO-PCT

[0092] Table 6Docket No. INV-23017-WO-PCT

[0093] Table 7Docket No. INV-23017-WO-PCT

[0094] Table 8

[0095] The fluid treatment system 400 is equivalent to the fluid treatment system 100 as described in Example 1, except:• the feed stream 401 entry is moved at or near the top of the first column 410;• no liquid side-stream is drawn from the first column 410;• the nitrile co-product stream 419 is added to the first column 410, and may optionally, be supplemented to the separator 430; and• a portion of the aqueous stream 421 from the separator 430 is fed at or near top of the second column 450 as stream 423 instead of feeding to the first column 410;

[0096] In the fluid treatment system 400, the stream 401 is >99 % (by wt.) water and contains <1% of the combined high-boiling nitriles, low-boiling nitriles, residual lighter organics, cyanides and ammoniacal species. Here, the stream 401 is unsuitable for a desired approach to bio-treatment, therefore, is not immediately fed to a bio-processing facility.Docket No. INV-23017-WO-PCT

[0097] The stream 401 is fed at or near the top of the first column 410. The recycle stream 437 from the vapor-liquid separator 480 is fed at or near the bottom of the first column 410. The recycle stream 437 is mostly water wherein the nitriles and lighter hydrocarbon species are concentrated to about 8 wt% or less. The recycle stream 437 is relatively small, amounting to less than 5% of stream 401. In the present example, a ratio of stream 437 : stream 401 is about 2.4% (by mass).

[0098] The top portion of the first column 410 receives about 48 kg / hr of stream 427. A very small nitrile co-product stream 419, rich in 2-pentenenitrile (2PN), may either be introduced to the first column 410 or to the separator 430.

[0099] The first column 410 includes a base reboiler configured to boil the feed and provide up-flowing vapor traffic in the first column 410. The down-flowing liquid in the first column 410 transports the organic and nitrile species from the up-flowing vapor and concentrates them at or near the base of the first column 410. The organic and nitrile species exit the first column 410 via the bottoms stream 411, which is about 18-20 % (by wt.) organics and nitriles, balance water. A liquid side-draw from the first column 410 is not taken in this example.

[0100] The first column 410 and the second column 450 overhead vapor streams, z.e., streams 403 and 413, respectively, are combined and cooled in heat exchange 420 to about 65 °C. The first column 410 overhead water-rich vapor stream 403 contains <1 wt% organics along with trace amounts of ammoniacal and cyanide species. The second column 450 overhead water-rich vapor stream 413 contains elevated levels of C6 organics, low-boiling nitriles, high-boiling nitriles, ammoniacal and cyanide species that are stripped out of stream 423 in the second column 450.

[0101] The cooled liquid stream 417 obtained from the heat exchanger 420 is fed to the separator 430. It is observed that the presence of 2-pentenenitrile (2PN) in the stream 417 is effective in partitioning the stream 417 into stream 443 (organic phase) and stream 421 (aqueous phase). The small overhead vaporous stream 445 from the separator 430 includes non-condensable components such as nitrogen, lighter organics and residual nitriles. Subsequently, the vapor stream 445 can be routed to a gas header for post-apparatus disposal.

[0102] The relatively heavy, aqueous stream 421, obtained from the separator 430, is split into two portions. A large portion is fed at or near the top section of the second column 450 as stream 423, while the remaining small portion is routed at or near the top section of the third column 460 as stream 422.Docket No. INV-23017-WO-PCT

[0103] The second column 450 is equipped with a reboiler at the base and is operated at the conditions that are desirable for stripping the cyanide species present in stream 423. About 80% of entering feed is recovered from the second column 450 bottoms as stream 415. The stream 415 contains <1 parts per million by weight (ppmw) cyanides and <500 ppmw residual organic impurities. The overhead vapor stream 413 consists mainly of water including elevated levels of the cyanides and organic impurities.

[0104] The aqueous stream 422 undergoes one more stripping pass in the third column 460 for concentration and removal of residual impurities via overhead stream 429. A steady flow of stripping stream 425 is sparged at the base of the third column 460 to strip the organic and nitrile impurities from the down-flowing liquid. The bottom stream 427 is mostly 99.8 wt% water with trace levels of impurities. The stream 427 is pumped back to the first column 410 to supplement separation in the first column 410. The overhead vapor stream 429, comprised mostly of 2PN, organics and residual cyanides, ammonia, etc., exits the third column 460, and can be subsequently routed toward a gas header for disposal.

[0105] The bottoms stream 411 from the first column 410 flows to the vacuum flash unit 470 operating at 110 °C and about 5.8 Psia (or 300 mmHg). The conditions in the vacuum flash unit 470 are maintained such that the majority of organic and nitrile impurities are concentrated at the bottom and discharged as stream 435. Stream 435 is less than 0.5 % (by mass) of stream 401. However, it is concentrated with the organic, nitrile, cyanide and trace metal impurities, desired to be removed from the stream 401. This concentrated organic stream 435, containing more than 95 wt.% impurities, can ease the necessary post-processing disposal steps.

[0106] It can be challenging to flow the concentrated stream 435 without the stream 435 thickening upon cooling. In the present example, a relatively small flow-assist stream 431 can be provided to overcome the challenge and to help facilitate a flowability of the stream 435. Although there is no restriction on the amount of the stream 431 used, mass ratios of about 45 : 1 for stream 411 : stream 431 can be preferred in the present example. In this example, the readily available co-product, crude 2-methylglutaronitrile (MGN), from a dinitrile production facility is used for the stream 431. The crude MGN may contain about 10-15% 2- ethylsuccinonitrile (ESN) and about 3-5% adiponitrile (ADN). However, there is no restriction against using other kinds of flow-assist agents such that they are chemically compatible with the components present in the stream 411 and with the appropriate equipment metallurgy. Examples of other nitriles that can be incorporated in the flow assist stream 431 include 2-Docket No. INV-23017-WO-PCT methyleneglutaronitrile, 2-ethyl succinonitrile, acrylonitrile, fumaronitrile, octanedinitrile, and decanedinitrile.

[0107] The stripped vapor stream 433, from the vacuum flash unit 470, is fed to the vapor-liquid separator 480. The separator 480 conditions are maintained such that the noncondensable stream 439 is separated from the liquid. The stream 439 may be routed to a gas header for subsequent treatment, for example, a scrubber or flare unit. The liquid stream 437, containing the residual impurities, is recirculated through the first column 410 for additional purification.

[0108] In this example, the disclosed apparatus desirably removes various impurities from the stream 401 down to the trace levels in the stream 415. These impurities include cyanides, ammoniacal species, C6 Organics, Light Organics, low-boiling, high-boiling Dinitriles and trace metals. The stream 415 can be fed to a bio-treatment step without posing any threat to the bio-mass health. The bio-treated aqueous stream is sufficiently clean to be reused and recycled to meet the site water conservation goal.

[0109] It may be feasible to either take either the entire stream 415 or a portion of stream 415 for clean water recycle in the apparatus, thereby meeting the goal of water conservation for the site. For example, stream 415 is sufficiently clean to be used in a quench column, water absorption column system, cooling systems, as boiler feed water, for dilution and other practical applications where clean water is needed. In one non-limiting example, about 10-20 % of the clean water stream 415 can be routed to the quench system as clean water for quenching. In another example, about 50% of the stream 415 can be taken for cooling and condenser operations.

[0110] In this example, and according to this disclosure, over 80% of the C6 Organics components present in stream 401 are concentrated in liquid stream 443 (organic phase), and the rest may end up in overhead vaporous stream 445. Both these streams may be routed for proper disposal. The disclosed apparatus is, therefore, effective in removing the C6 organic impurities from stream 401.[OHl] In this example, and according to this disclosure, over 90% of the Light Organics components in stream 401 are concentrated in stream 435, which is routed for proper disposal, incineration for example. The disclosed apparatus is, therefore, effective in removing the Light organics impurities from stream 401. Optionally, the Light Organics and High- Boiling Dinitriles concentrated stream 435 can be recycled back in the industrial apparatus to improve the useful atomic yield recovery efficiency for the entire apparatus. In this example,Docket No. INV-23017-WO-PCT the stream 435 containing higher than 80 wt% of some useful nitriles and dinitriles can be recycled back to the nitriles recovery step in the apparatus.

[0112] In this example, according to this disclosure, the majority of Low-boiling Nitriles components in stream 401 are concentrated in stream 443, which is routed for proper disposal. The disclosed apparatus is, therefore, effective in removing the Low-boiling Nitriles from stream 401. Optionally, the C6 Organics and Low-Boiling Nitriles concentrated stream 443 can be recycled back in the industrial apparatus to improve the useful atomic yield recovery efficiency for the entire apparatus.

[0113] In this example, and according to this disclosure, the majority of High-boiling dinitriles components in stream 401 are concentrated in stream 435, which is routed for proper disposal. The disclosed apparatus is, therefore, effective in removing the High-boiling dinitriles from stream 401.Example 10

[0114] The fluid treatment system, as described in Example 9, is operated except the aqueous stream 422 feed to the third column 460 is reduced to more than half. A steady flow of the stripping stream 425 is sparged at the base of the third column 460 to strip the organic and nitrile impurities from the down-flowing liquid in the third column 460. It is observed that the amm oniacal species begin to accumulate and condense in the overhead streams 413 and 445, thereby causing difficulties to operate at steady-state.

Claims

Docket No. INV-23017-WO-PCTCLAIMSWhat is claimed is:

1. A process to treat an aqueous stream; the process comprising: receiving or accessing an aqueous stream from an industrial system, the aqueous stream having between 10-1000 parts per million by weight (ppmw) cyanide-containing species, between 0.5-500 ppmw metal contaminants and between 10-10000 ppmw organic species; providing the aqueous stream to a distillation system; providing or obtaining a vapor stream and a liquid stream from the distillation system; cooling the vapor stream to obtain a cooled liquid stream; introducing an additive to the cooled liquid stream to separate a phase of the cooled liquid stream; concentrating the liquid stream to produce an impurity-rich liquid stream; removing the impurity-rich liquid stream by co-flowing with a flow-assist agent; and recovering a treated aqueous stream having < 0.5 ppmw cyanide-containing species, < 1 ppmw metal contaminants and < 5 ppmw organic species.

2. The process of claim 1, wherein the distillation system includes at least of stripping, rectifying, concentrating, flashing, steam stripping, pump-around, side-draw, reflux, condensation, reboiler, phase separation, decantation, and combinations thereof.

3. The process of claim 1, wherein the cyanide-containing species are selected from the group consisting of hydrogen cyanide, sodium cyanide, potassium cyanide, ammonium cyanide and cyanide ions.

4. The process of claim 1, wherein the metal contaminants comprise Group 3 through Group 12 of the Periodic Table of Elements.

5. The process of claim 4, wherein the metal contaminants are selected from the group consisting of iron, nickel, copper, cobalt, chromium, arsenic, cadmium, lead, antimony, mercury and zinc.Docket No. INV-23017-WO-PCT6. The process of claim 1, wherein the organic species are selected from the group consisting of benzene, cyclohexane, phenols, cresols, Ci-Cs mononitriles and Cs-Cs dinitriles.

7. The process of claim 6, wherein the Ci-Cs mononitriles are selected from the group consisting of hydrogen cyanide, acetonitrile, propionitrile, butanenitrile, butenenitrile, valeronitrile, pentenenitrile, hexanenitrile, hexenenitrile, heptanenitrile, heptenenitrile, octenenitrile and octanenitrile.

8. The process of claim 6, wherein the Cs-Cs dinitriles are selected from the group consisting of malononitrile, succinonitrile, glutaronitrile, adiponitrile, 2-methylglutaronitrile, 2-ethylsuccinonitrile and 2-methyleneglutaronitrile.

9. The process of claim 1, wherein the additive comprises a cycloalkane or an organic nitrile.

10. The process of claim 9, wherein the additive comprises cyclohexane.

11. The process of claim 9, wherein the additive comprises an organic nitrile selected from the group consisting of 2-pentenenitrile, 3 -pentenenitrile, 4-pentenenitrile, 2-methyl-2- butenenitrile, 2-methyl-3 -butenenitrile, 2-methyl-glutaronitrile, acetonitrile, propionitrile, adiponitrile, 2-ethyl-succinonitrile, 2-methylene-glutaronitrile and acrylonitrile.

12. The process of claim 11, wherein the additive comprises cis-2-pentenenitrile.

13. The process of claim 1, wherein the flow-assist agent comprises an organic dinitrile selected from the group consisting of 2-methyl-glutaronitrile, adiponitrile, 2-ethyl- succinonitrile, 2-methylene-glutaronitrile, succinonitrile, acrylonitrile, fumaronitrile, octanedinitrile, and decanedinitrile.

14. The process of claim 13, wherein the flow-assist agent comprises 2-methyl- glutaronitrile.Docket No. INV-23017-WO-PCT15. The process of claim 1, wherein the treated aqueous stream is provided as a feed to a process unit operation selected from the group consisting of steam boiler as boiler feed water, heat exchanger, condenser, quench column, bio-treatment step, electrolysis process for hydrogen gas generation and dilution system.

16. The process of claim 1, wherein the treated aqueous stream is provided to a biological treatment facility to generate a substantially clean water stream.

17. The process of claim 1, wherein the impurity-rich liquid stream comprises < 10% water of a total impurity -rich liquid stream mass.

18. The process of claim 1, wherein a pH of the distillation system is maintained in a range selected from 5.0 to 8.5, from 5.1 to 8.0, from 5.2 to 7.5, from 5.3 to 7.5, from 5.4 to 7.0 and from 5.5 to 6.5.

19. The process of claim 18, wherein the pH of the distillation system is maintained by introducing an acid to the distillation system.

20. The process of claim 19, wherein the acid is selected from the group consisting of sulfuric acid, phosphoric acid, phosphorous acid, acetic acid, carbonic acid, formic acid, hydrochloric acid, nitric acid, hydrofluoric acid, oxalic acid and propionic acid.

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