ABS EMULSION POLYMERIZATION PROCESS

RELATED APPLICATION

[0001] The present application claims priority to and the benefit of United States application 62/144,127, "Recycle Water for Emulsion ABS Process" (filed April 7, 2015), the entirety of which application is incorporated herein by reference for any and all purposes.

TECHNICAL FIELD

[0002] The present disclosure relates to water recycling and more specifically to recycling water used in the production of acrylonitrile-butadiene-styrene.

BACKGROUND

[0003] Acrylonitrile-butadiene-styrene (ABS), copolymers derived from acrylonitrile, butadiene, and styrene monomers, exhibit excellent impact resistance and toughness. In particular, ABS materials combine the strength and rigidity of the acrylonitrile and styrene polymers with the toughness of the polybutadiene rubber. The large scale production of these ABS materials can generate significant amounts of waste gas, solid waste, and waste water.

SUMMARY

[0004] Requiring styrene, acrylonitrile, and a number of auxiliary agents, the production of ABS resin can proceed through a water intensive process such as emulsion, suspension, or bulk/suspension polymerization processes. Indeed, an emulsion polymerization process for ABS can consume a significant amount of water in the reaction and during subsequent resin isolation processes. Generally, ABS process waste water can be pretreated to adjust for pH and the waste solids can be removed. After this pre-treatment, the wastewater can be sent to an industrial wastewater treatment facility to be purified prior to discharge in a receiving water supply. As water resources become scarcer and more valuable globally, however, it is desirable to purify and recycle the process wastewater for reuse within the ABS production system. In an ABS production system utilizing both demineralized (DM) water and process water during polymerization and isolation processes, water quality can thus be vitally important. To further complicate using recycled water, the wastewater can be contaminated with a variety of constituents including polymer, residual monomer, and several additives unconsumed during the reaction process. Accordingly, it would be beneficial to provide an efficient system for cleaning and recycling wastewater of an ABS production facility.

[0005] As described in more detail herein, the present disclosure provides a process, apparatuses, and systems for recycling water used in ABS polymerization processes.

[0006] More specifically, the present disclosure describes a process for recycling wastewater comprising directing wastewater from an ABS production facility through a filtration system and subjecting the wastewater to a series of processes including chemical oxidation, chemical neutralization and precipitation, biological treatment, advanced oxidation, alkalinity removal, hardness polishing, and purification. In certain aspects, subsequent the series of processes, the wastewater may have a total solids content of less than 10 parts per million (ppm) or less than about 10 ppm.

DETAILED DESCRIPTION

[0007] The production of ABS copolymer resins according to an emulsion polymerization process can generate waste gas, solid wastes, and waste water. The emulsion polymerization process can require the consumption of significant amounts of both process water and purified demineralized water. The production of ABS copolymer resin can require water in various phases throughout the applicable processes. An emulsion polymerization can comprise a first latex stage through which polybutadiene latex is prepared using a water solvent and butadiene monomers with a catalyst, such as a radical initiator. The polybutadiene can be agglomerated in water solvent to increase the latex particle size. In a subsequent emulsion polymerization process, the generated polybutadiene latex can be a rubber substrate onto which acrylonitrile and styrene monomers can be graft polymerized in a water solvent in the present of a surfactant and radical initiator to provide an ABS latex. The ABS latex can then undergo an isolation process wherein the latex can be first exposed to a mixture of water and a coagulant, such as an acid, to provide a wet ABS resin slurry. The slurry can be dewatered, washed, and again dewatered before the wet ABS resin can be dried to provide the final ABS resin. The described processes (a first emulsion polymerization, a graft emulsion polymerization, agglomeration, and isolation), can consume significant amounts of purified (demineralized) water and process water. Indeed, in one example, 0.2 to 1.0 kilograms (kg) of DM water can be used per 1.0 kg of ABS produced. An additional 1.0 to 4.0 kg/kg of process water can be used per kg of ABS produced. Based on the typical scale of a 300 kilo tons per annum (kta) ABS facility, these amounts can total to up to 1.5 billion kg of water usage annually. [0008] In various aspects, an ABS production system that can recycle the wastewater generated throughout the production process can be embodied in the system of processes disclosed herein. The disclosed wastewater recycling system can comprise a filtration process, a chemical oxidation process, a chemical neutralization process, a biological treatment process, an advanced oxidation process, a hard water polishing process, and a reverse osmosis purification process.

[0009] The present disclosure can be understood more readily by reference to the following detailed description of the disclosure and the Examples included therein.

ACRYLONITRILE BUTADIENE STYRENE PRODUCTION

[0010] In various aspects, the present disclosure relates to an acrylonitrile butadiene styrene (ABS) resin production process comprising the disclosed waste water recycling system. In a further aspect, the ABS resin production process can be configured to incorporate the disclosed waste water recycling system.

[0011] In one aspect, the preparation of the high rubber graft ABS copolymer resin can proceed through a polymerization process wherein styrene and acrylonitrile monomers are grafted onto a polybutadiene latex rubber substrate in a batch or continuous polymerization process. Here, the precursor polybutadiene latex rubber can be prepared according to a similar emulsion polymerization process using butadiene monomers, emulsifiers, and radical initiator. In further aspects, the ABS copolymer resin can be prepared by blending emulsion latexes of styrene acrylonitrile (SAN) and nitrile rubber (NBR). In an example, the polymerization process to yield an ABS resin can proceed through an ABS latex phase. The ABS latex phase can be further processed to provide the desired ABS resin.

[0012] In various aspects, the high rubber graft ABS copolymer can be prepared by polymerization processes including emulsion, suspension, sequential emulsion- suspension, bulk and solution polymerization processes. These methods are known in the polymerization art, specifically directed toward the preparation of a wide variety of high rubber graft copolymers for impact modification of thermoplastic resins. Suitable specific embodiments of the particular impact modifiers can be prepared by any aforementioned polymerization means. Preferred polymerization processes can proceed in an aqueous media and include emulsion and suspension methods. A preferred process for preparing the rubbery portion can be by way of emulsion polymerization as taught in the art.

[0013] In one example, a graft (emulsion) polymerization to provide a grafted rubber latex (e.g., an ABS latex), can include charging a reactor system with water and a substrate such as a diene rubber latex (polybutadiene latex), adding a first portion of at least one of a styrene and one of an acrylonitrile to the polybutadiene latex, adding to the reaction system over a predetermined time a catalyst (a radical initiator) and a second portion of at least one of acrylonitrile and styrene monomers, and polymerizing the catalyzed reaction mixture of polybutadiene latex, styrene and acrylonitrile. The graft polymerization process can also include an emulsifier to facilitate formation of the grafted ABS copolymer resin. As noted herein, water can be used as the solvent for the polymerization process. In a given continuous emulsion polymerization process, water can be directed into the polymerization reactor at a steady rate to serve as the aqueous medium. This water can be purified or demineralized to ensure that the water has little or minimal reactive components that can affect the polymerization process. In one aspect, the water solvent of the emulsion polymerization process can comprise the desired latex, unreacted monomers, surfactants, among other reagents for the emulsion process. After isolation of a generated latex (whether as a rubber substrate intermediary or a final grafted latex), the emulsion polymerization water solvent comprising unreacted monomers, oligomers, residual polymer, minerals, among other contaminants, can be combined with other waste water generated in the polymerization process, such as during coagulation.

[0014] In further aspects, a (high rubber graft) HRG ABS can be prepared by graft polymerizing less than about 50 wt % of at least one rigid monomer such as a vinyl aromatic monomer, an acrylic monomer, a vinyl nitrile monomer or a mixture thereof in the presence of more than about 50 wt % of a preformed rubbery polydiene substrate such as 1,3-diene polymer or copolymer thereof. Further, a HRG ABS can be prepared by graft polymerizing less than 50 wt % of at least one rigid monomer such as a vinyl aromatic monomer, an acrylic monomer, a vinyl nitrile monomer or a mixture thereof in the presence of more than 50 wt % of a preformed rubbery polydiene substrate such as 1,3-diene polymer or copolymer thereof. In particular, the graft copolymers can comprise from 50 wt % to 90 wt % of a rubbery substrate polydiene such as for example polybutadiene latex to provide a graft ABS latex.

[0015] In another aspect, the generated ABS latex from the emulsion polymerization process can be further processed via coagulation using a salt or caustic acid to provide an output ABS slurry. The slurry can comprise water, the wet ABS resin, and coagulant. During the coagulation process, fine particulates can agglomerate or clump together and accumulate at the top or settle at the bottom of the slurry. The agglomerated particles can be separated or harvested via a filtration or centrifuge process to remove water and provide an output wet ABS resin. The removed water can be directed to facility waste (i.e., designated as wastewater). The wet ABS resin can then be washed with purified water to eliminate coagulant residue and dewatered to isolate the resin, the "dewatering" liquid proceeding to facility waste (i.e., wastewater). Finally, the ABS resin can then be dried under heat to remove moisture and provide the final ABS copolymer resin. In an aspect, the polymerization and subsequent isolation processes can afford a dried, isolated high rubber graft copolymer resin wherein at least about 30% by weight of the rigid polymeric phase is chemically bound or grafted to the rubbery polymeric phase. In a still further aspect, at least about 45% by weight of the rigid polymeric phase is chemically bound or grafted to the rubbery polymeric phase. In some aspects, the high rubber graft ABS can have a rubber content less than or equal to about 95 wt % by weight of the graft polymer. In some aspects, the polymerization and subsequent isolation processes can afford a dried, isolated high rubber graft copolymer resin wherein at least 30 % by weight, at least 45% by weight, or at least 90% by weight of the rigid polymeric phase is chemically bound or grafted to the rubbery polymeric phase. Preparation of the ABS resin can have consumed upwards of 0.2 kg of water for each 1.0 kg of ABS resin generated. Indeed, in one example, 0.2 to 1.0 kilograms (kg) of demineralized (DM) water can be used per 1.0 kg of ABS produced.

[0016] In various aspects, the water used during the preparation of the ABS resin (waste water) can be treated for recycled usage in the ABS production process. For example, the waste water can be subjected to a series of processes to make the waste water suitable for reintroduction into the ABS production process. The system of recycling waste water can include a filtration process, a chemical oxidation process, a chemical neutralization process, a biological treatment process, an advanced oxidation process, an alkalinity removal process, and a reverse osmosis process.

[0017] In various aspects, a given ABS facility can generate untreated waste water comprising volatile organic compounds, solids, residual polymer, unreacted monomers such as styrene and acrylonitrile, among a number of other constituents undesirable, or unsuitable, for release into a receiving water supply. The ABS production facility can produce this untreated wastewater at an average flow of 100 cubic meters per hour or about 100 cubic meters per hour (m ³ /hr), for a daily average flow of 2,400 cubic meters per day (CMD). The normal flow can be 200 m ³ hr or about 200 m ³ /hr, with a peak of 220 m ³ /hr or about 220 m /hr at 60 °C or about 60 °C. The unprocessed wastewater of an ABS facility can have a pH of from 2 to 3 or from about 2 to about 3. With respect to microbial and chemical contaminants, unprocessed wastewater can have levels of biological oxygen demand (BOD) and chemical oxidation demand (COD) respectively. In an example, the unprocessed wastewater can have a BOD of 600 ppm or about 600 ppm, the value corresponding to the amount of oxygen required by micro-organisms to degrade the organic matter in the waste water. The COD, which can refer to the total measure of all chemicals in the wastewater (organic or inorganic), can be about 1,800 ppm. Other elements present can include sulfates (2,100 ppm or about 2,100 ppm) and phosphorous (80 ppm). At a pH of between 2 and 3, the wastewater can also contain total dissolved solids (TDS) in an amount of 2,400 ppm or about 2,400 ppm. Total suspended solids, in other words, solids that can be filtered from the wastewater, can also be present in the untreated waste water in an amount of 1,000 ppm or about 1,000 pm. In various further examples, it can be assumed that unprocessed wastewater can have less than 100 ppm or about 100 ppm of calcium and magnesium cations and less than 50 ppm or less than about 50 ppm sodium and potassium cations as well as an alkalinity of less than 110 ppm or less than about 110 ppm present as calcium carbonate. The total solids content may be determined according to a testing standard such as ASTM D1417-10, Standard Test Methods for Rubber Latices - Synthetic. The ASTM D1417-10 standard may be used to evaluate a number of characteristics of the wastewater. For example, the pH, surface tension, viscosity, and mechanical stability may be observed according to ASTM D1417-10.

WASTEWATER RECYCLING SYSTEM

[0018] In an aspect of the invention, wastewater subjected to a system of processes to maximize the amount of purified water that can be retained. The systems can comprise a filtration process, a chemical oxidation process, a chemical neutralization process, a biological treatment process, an advanced oxidation process, an alkalinity removal process, and a reverse osmosis purification process. Each process can perform a unique step in the overall water recycling system.

FILTRATION

[0019] In one aspect, the wastewater recycling process can comprise a filtration process system. The filtration process can comprise a filter, for example, a self-cleaning filter, having a filter media designed to separate the undesired particulate. The filter media can comprise a metal screen. The filtration system can be configured to receive all wastewater feed streams from the ABS production facility. In an example, the process filter can function as a sieve thereby preventing the passage therethrough of larger particles. In a filter process, the combined feed streams of wastewater from the emulsion polymerization process can be screened to eliminate particulate greater than 1 mm, or greater than about 1 mm, in size. In further examples, the combined feed streams of wastewater can be screened to eliminate particulate greater than 50 μπι θΓ greater than about 50 μπι, greater than 100 μηι or greater than about 100 μπι, greater than 200 μηι or greater than about 200 μηι, or greater than 500 μηι or greater than about 500 μηι. In a specific example, the combined feed of streams of wastewater from the emulsion polymerization process can be screened to eliminate particulate as small as 200 μιη, or about 200 μιη. In various aspects of the present disclosure, the particulate present in a wastewater stream may be of a certain size. Generally, the particulate is a solid, having a defined size and shape. As such, the size of these particles may be measured according to a number of appropriate techniques. Exemplary techniques for assessing particulate size may include light scattering, laser diffraction optical microscope, Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Atomic Force Microscopy (AFM), electroacoustic techniques. Commercial MESH sieve dimensions related to particle size may also be applicable and are referenced as in ISO 565 (1990). As a further example, a spectrophotometer, such as a Thermo Scientific Genesys 20 spectrophotometer, may be used to measure particle size.

[0020] In an aspect, the filter of the filtration process can be self-cleaning. Self-cleaning can refer to the ability of the filter to be periodically backwashed to flush and divert any solids that have accumulated on the surface of the filter.

CHEMICAL OXIDATION

[0021] In one aspect, the wastewater recycling system can comprise a chemical oxidation process. In various aspects, the chemical oxidation process can comprise directing the filtered wastewater to a stirred reactor tank and introducing either hydrogen peroxide or sodium persulfate via a dosing system configured to deliver the oxidizing agents. In an example, the peroxide and/or persulfate can be used to decompose the hard (refractory, or heat resistant) COD, thereby converting the COD to a biodegradable COD grade. As noted herein, a subsequent biological treatment process can be used to remove this biodegradable grade COD.

[0022] In further aspects, the chemical oxidation process can further comprise the use of a dosing system, aeration diffusers and blowers. The aeration diffusers can be used to ensure a proper distribution of air throughout the oxidation tank. The blowers can supply an abundance of air (oxygen) to drive the process of oxidation. The stirred reactor tank can also be configured to function as an equalization tank to balance flow to subsequent sections downstream in the water recycling system. As an equalization tank, the levels in the tank can be permitted to fluctuate. This fluctuation can enable equalization of the outlet flow rate of the tank. The outlet flow rate from the tank can be held near a consistent rate while the flow into the tank can fluctuate.

CHEMICAL NEUTRALIZATION

[0023] In one aspect, the disclosed wastewater recycling system can comprise a chemical neutralization and precipitation process. The wastewater can be pumped to a tank reactor for initiation of the chemical neutralization and precipitation process using caustic soda and soda ash. The tank reactor can comprise concrete. In the tank reactor, caustic soda (sodium hydroxide) can be introduced to neutralize the water and to increase the pH of the wastewater to between 8 and 12, for example to 10 or to about 10 The reactor can be agitated. The amount of caustic soda added can depend upon the incoming pH of the wastewater. For example, where the pH of the incoming wastewater is lower, the more caustic soda (having a pH 13 - 14) can be needed. In some aspects, the increase in pH can precipitate heavy metals, phosphates, and some COD and BOD present in the wastewater. In one example, soda ash can also be added to facilitate precipitation of calcium as calcium carbonate. In further examples, a polyelectrolyte can then be used to enhance precipitation. The polyelectrolyte can as a flocculating agent thereby inducing small particles to agglomerate or clump. Overflow of the resulting wastewater and sludge (precipitate) mixture can be directed to a clarifier. The clumped particles are heavier and can then sink in the clarifier. The clarifier can provide a large volume capacity container allowing slowing the wastewater and allowing particles or precipitate (sludge) to clump together and sink while the clarified wastewater can be directed through the rest of the wastewater recycling system. As noted, the polyelectrolyte can facilitate the sinking of large agglomerated clumps. In the absence of the polyelectrolyte, the particles or particulate can settle suspended at the top of the large volume container. Should the sludge or particulate remain at the top or surface, it can continue with the flow of the wastewater and clog or blog the remainder of the wastewater treatment process. The clarified wastewater flow can be directed from top of the clarifier and to the biological treatment process. In some examples, the wastewater of the clarifier can also be separated from the particulate and sludge via filtration. Decanted filtrate wastewater can then be reintroduced into the recycling system for reprocessing.

BIOLOGICAL TREATMENT PROCESS

[0024] In one aspect, the wastewater recycling system can comprise a biological treatment process. Moreover, after the wastewater has been chemically pretreated in the chemical oxidation and neutralization processes, the wastewater can undergo a biological treatment process in a biological treatment subsystem. In an example, the biological treatment process can be enacted to remove a significant amount of COD and BOD present in the wastewater. In one aspect, the biological treatment process can comprise directing the wastewater through a biological treatment subsystem, here, a membrane bioreactor (MBR) system with submerged membrane modules. In one example, the membrane bioreactor system can comprise one or more bioreactors. Each bioreactor can be configured to fit into a process tank. The tanks can be provided with air for aeration and can contain the submerged membrane modules. Two aeration tanks can be provided, each with 50% capacity. For an MBR module, two tanks each having a 100 % capacity can be provided. [0025] In one aspect, an operation method for the biological treatment process and system can comprise aerating the wastewater- sludge mixture, discharging a produced surplus sludge, and regenerating the membrane modules. For example, influent water can be received from the chemical pretreatment processes and can be transferred to the membrane bioreactors. Should the water temperature be greater than the acceptable temperature for the biological process (which is likely will be coming from chemical pretreatment), the water can be cooled by means of a closed cooling system (heat exchange) of the reactors. As an example, the water can be cooled to a desired control temperature of 38 °C, or about 38 °C. The cooling water can first be filtered in order to prevent blockage in the spray nozzles.

[0026] Once in the membrane bioreactors, the influent water/sludge mixture can be aerated intensively. The aeration can cause an aerobic reduction of biodegradable carbon to occur. This aerobic reduction can also result in sludge and biomass being held in motion. Overflow from the aeration tank can be transferred to the MBR tanks (each can be at 100% capacity). Separation of the filtrate and sludge can be achieved by the membrane modules installed within the MBR tanks. In an example, the membrane filtration module can be fully immersed into the sludge. Permeate pumps can be disposed within the system to withdraw the treated water and direct the water to the subsequent phase of the treatment process.

[0027] In some aspects, a foam can form in the aeration tank during aeration of the influent water/sludge mixture. In an example to combat foaming, an antifoam dosing system can be introduced into the aeration tank. In a further example, a nutrients dosing system can be provided aid the survival, and efficiency, of the biologic agents within the MBR tank. The level of nutrients can be diminished where there is a shutdown or similar interruption in the flow of the wastewater recycling system. The anti-foaming system and nutrient system can be equipped with two dosing pumps (ID /1SB) and one dosing tank.

[0028] In various further aspects, excess sludge can be generated during the biological treatment process and can be referred to as a "surplus sludge." The generated surplus sludge in the biological tank can be discharged when an adjustable value for suspended solids in the water sludge mixture is reached. In one example, a soak truck can be used to periodically remove the surplus sludge discharge directly from the aeration tank. During operation the usual concentration of the suspended solids within the water sludge mixture can reach up to 15,000 milligrams per liter, mg/1. The adjustment of solids can be based on operation settings according to manual daily measurement.

[0029] In an aspect, to maintain optimal function of the MBR system, chemical cleansing of the filtration membrane module can be performed. On average, the frequency of membrane regeneration for wastewater treatment can be about six months. Deposits of organic and/or inorganic substances can accumulate on the surface of the filtration membrane modules, thus requiring regeneration of the membrane. In an example, the regeneration frequency can be significantly influenced by the characteristics of the liquid media and the differential pressure used in the membrane filtration process. Membrane regeneration can be performed in the same bioreactor tank and does not need a separate system. In one example, an inline chemical dosing system can be provided for chemically cleaning the system.

ADVANCED OXIDATION SYSTEM

[0030] In one aspect, the wastewater recycling system can comprise further oxidation processes. An advanced oxidation process can comprise subjecting the wastewater to ozone, UV, and hydrogen peroxide.

[0031] As an example, an ozone generation system having advanced controls can be used to inject ozone into the wastewater stream. A high performance static mixer and tank can be used to provide mixing time. The mixing time can further reduce the load of COD/BOD in the wastewater.

HARDNESS POLISHING AND ALKALINITY REMOVAL SYSTEM

In one aspect, the wastewater recycling system can comprise an alkalinity removal process. The alkalinity removal process can be configured to alter the hardness of the wastewater. Hardness of the wastewater can refer to the amounts of minerals such as calcium and magnesium present in the wastewater. In an example, the wastewater can be first acidified with an acid such as, for example, sulfuric acid, to convert all bicarbonate or carbonate alkalinity to carbon dioxide gas. The carbon dioxide gas can be stripped in an aeration buffer tank. Upon removal of the alkalinity, the wastewater can be directed to one or more water softeners. The water softener can comprise resin beds configured to trap remaining hardness components in the wastewater. Once the capacity of the water softener is expended, the water softener can be replenished using a sodium chloride solution while another softener can be put online.

REVERSE OSMOSIS PROCESS

[0032] In one aspect, the wastewater recycling system can comprise a reverse osmosis process. The reverse osmosis process can include multiple units or osmosis chambers. A first unit can be referred to as a primary reverse osmosis unit (primary RO) and a second unit can be a brine recovery unit. Generally, the RO units can comprise vessels equipped with specialized membranes. In one example, a caustic soda can be introduced into the feed stream of wastewater into a vessel to adjust the pH of the wastewater to between 8 and 12, for example, to 10 or to about 10. In various aspects, an elevated pH can be used to prevent biological and organic fouling of wastewater which has been treated to remove hardness attributed to minerals or scale forming minerals which can solidify at high pH. An anti-scalant dosing pump can be configured to deliver dose metered quantities of an anti-scaling chemical into the wastewater. This anti- scalant chemical can be introduced into the wastewater prior to entrance of the wastewater into a cartridge filter of the primary RO system. The wastewater can then proceed to filtration through the cartridge filter within a cartridge filter housing of the primary RO. The cartridge filter can have a 5-micron rating installed and can be disposed at an inlet of a reverse osmosis train. The cartridge filter can protect the high pressure pump and the reverse osmosis membranes from suspended solids that may have passed through the media filter. For example, the media filter and cartridge can be disposed prior to a primary RO unit feed pump which can direct the waste water into the RO unit. A high-pressure pump can then direct the filtered and chemically treated raw wastewater to the reverse osmosis membranes at high pressure. In an example, as pressurized waste water is fed to the reverse osmosis membrane, purified water can pass through the membrane while salts are retained in the pressurized side of the membrane. This pressured side containing salts can be referred to as a brine side. The treated, purified water obtained from the primary RO unit can be collected in a manifold and then directed into a storage tank. In certain aspects, the treated wastewater may have a total solids content of less than 10 ppm or less than about 10 ppm. Any brine rejected from the reverse osmosis membrane can continuously be removed. This brine can be collected and subjected to treatment in the brine recovery reverse osmosis unit. In one example, 10% or about 10% of the incoming wastewater into the primary RO unit can be discharged from the RO unit as a concentrated stream that is disposed of to an industrial wastewater treatment system or receiving body of water.

[0033] In one aspect, the brine collected during the primary reverse osmosis unit can directed to a brine recovery reverse osmosis unit. In the brine recovery RO unit, further water can be recovered from the rejected brine. In an example, the brine can be sent to a buffer tank to alleviate flow fluctuations. An anti-scalant dosing system can also be used to prevent scaling in the brine recovery RO unit. Brine from this buffer tank can be fed to a brine recovery RO unit filter feed pump. The filter feed pump can pump through a filter housing to protect the high pressure brine recovery RO feed pump from damage from any particulates. The high pressure pump can feed the brine recovery RO unit. For example, 30% or about 30 % of the incoming wastewater can be discharged from the RO unit as a concentrated steam. The steam can be disposed of to an industrial wastewater treatment system or receiving body of water.

METHOD [0034] The disclosure contains processes configured to recycle wastewater generated during the manufacture of ABS polymer resins. Certain processes can relate to subjecting the wastewater to a system of one or more processes that each perform a separate function in recycling the wastewater. The method can comprise any or all of the processes described above. One method of recycling the wastewater can comprise subjecting the wastewater through all of the processes of the system described. The methods disclosed herein can comprise filtration, chemical oxidation, chemical neutralization and precipitation, biological treatment, an advanced oxidation system, alkalinity removal system, and reverse osmosis.

[0035] The disclosure concerns methods of recycling water consumed during an emulsion polymerization through a water purification system. One method can comprise multiple steps for recycling water used in a batch emulsion polymerization process. In an example, a first step can comprise discharging wastewater from an ABS unit to a filtration process. The filtration process can comprise a self-cleaning filter configured to separate solid particulate from the wastewater. A chemical oxidation process can follow wherein the pH of the wastewater is adjusted. The wastewater can then be neutralized with caustic soda raising the pH to between 8 and 12, or for example, to 10 or to about 10 and thereby precipitating heavy metals, phosphates. The wastewater can then be cooled and directed to a biological treatment process tank, the process configured to reduce the organic load and microbial level of the wastewater. An advanced oxidation can be performed to further reduce organic load. The wastewater can then be introduced to a reverse osmosis process system. In certain aspects, the methods disclosed herein may provide a wastewater having a total solids content of less than 10 ppm or less than about 10 ppm.

[0036] While aspects of the present disclosure can be described and claimed in a particular statutory class, such as the system statutory class, this is for convenience only and one of skill in the art will understand that each aspect of the present disclosure can be described and claimed in any statutory class. Unless otherwise expressly stated, it is in no way intended that any method or aspect set forth herein be construed as requiring that its steps be performed in a specific order. Accordingly, where a method claim does not specifically state in the claims or descriptions that the steps are to be limited to a specific order, it is no way intended that an order be inferred, in any respect. This holds for any possible non-express basis for interpretation, including matters of logic with respect to arrangement of steps or operational flow, plain meaning derived from grammatical organization or punctuation, or the number or type of aspects described in the specification.

ASPECTS [0037] The disclosed systems and methods include at least the following aspects.

[0038] Aspect 1. A wastewater recycling system comprising a series of processes, the series of processes comprising: directing a raw wastewater influent through a filtration device to separate solids from the wastewater influent, the filtration device comprising a self-cleaning filter, wherein at least a portion of the raw wastewater is sourced from an emulsion polymerization process; subjecting the filtered wastewater influent to a chemical pretreatment process wherein a first oxidizing agent is introduced to the filtered wastewater influent to degrade any refractory chemical oxygen demand to a biodegradable chemical oxygen demand and then the oxidized wastewater influent is charged with a first additive to raise the pH to 10 or about 10 to form a precipitate in the oxidized wastewater influent; separating the precipitate from the oxidized wastewater influent to remove all settled particles and directing the separated wastewater influent through a bioreactor to aerobically reduce carbon present in the separated wastewater to provide a biologically treated wastewater, the bioreactor containing membrane modules submerged in an activated sludge; acidifying the biologically treated wastewater to convert bicarbonate or carbonate alkalinity to carbon dioxide gas, the carbon dioxide gas removed in an aeration buffer tank; directing the acidified wastewater influent through a water softening subsystem to remove any residual mineral content in the acidified wastewater; introducing a second additive to increase the pH of the acidified wastewater and directing a feedstream of the resultant wastewater through a reverse osmosis unit, the wastewater pressurized to facilitate flow through a membrane of the reverse osmosis unit, wherein the wastewater as outputted from the reverse osmosis unit has a total solids content of less than 10 ppm.

[0039] Aspect 2. A wastewater recycling system comprising a series of processes, the series of processes comprising: directing a raw wastewater influent through a filtration device to separate solids from the wastewater influent, the filtration device comprising a self-cleaning filter, wherein at least a portion of the raw wastewater is sourced from an emulsion polymerization process; subjecting the filtered wastewater influent to a chemical pretreatment process wherein a first oxidizing agent is introduced to the filtered wastewater influent to degrade any refractory chemical oxygen demand to a biodegradable chemical oxygen demand and then the oxidized wastewater influent is charged with a first additive to raise the pH to 10 or about 10 to form a precipitate in the oxidized wastewater influent; separating the precipitate from the oxidized wastewater influent to remove all settled particles and directing the separated wastewater influent through a bioreactor to aerobically reduce carbon present in the separated wastewater to provide a biologically treated wastewater, the bioreactor containing membrane modules submerged in an activated sludge; acidifying the biologically treated wastewater to convert bicarbonate alkalinity to carbon dioxide gas, the carbon dioxide gas removed in an aeration buffer tank; directing the acidified wastewater influent through a water softening subsystem to remove any residual mineral content in the acidified wastewater; introducing a second additive to increase the pH of the acidified wastewater and directing a feedstream of the resultant wastewater through a reverse osmosis unit, the wastewater pressurized to facilitate flow through a membrane of the reverse osmosis unit, wherein the wastewater as outputted from the reverse osmosis unit has a total solids content of less than 10 ppm.

[0040] Aspect 3. A wastewater recycling system comprising a series of processes, the series of processes comprising: directing a raw wastewater influent through a filtration device to separate solids from the wastewater influent, the filtration device comprising a self-cleaning filter, wherein at least a portion of the raw wastewater is sourced from an emulsion polymerization process; subjecting the filtered wastewater influent to a chemical pretreatment process wherein a first oxidizing agent is introduced to the filtered wastewater influent to degrade any refractory chemical oxygen demand to a biodegradable chemical oxygen demand and then the oxidized wastewater influent is charged with a first additive to raise the pH to 10 or about 10 to form a precipitate in the oxidized wastewater influent; separating the precipitate from the oxidized wastewater influent to remove all settled particles and directing the separated wastewater influent through a bioreactor to aerobically reduce carbon present in the separated wastewater to provide a biologically treated wastewater, the bioreactor containing membrane modules submerged in an activated sludge; acidifying the biologically treated wastewater to convert carbonate alkalinity to carbon dioxide gas, the carbon dioxide gas removed in an aeration buffer tank; directing the acidified wastewater influent through a water softening subsystem to remove any residual mineral content in the acidified wastewater; introducing a second additive to increase the pH of the acidified wastewater and directing a feedstream of the resultant wastewater through a reverse osmosis unit, the wastewater pressurized to facilitate flow through a membrane of the reverse osmosis unit, wherein the wastewater as outputted from the reverse osmosis unit has a total solids content of less than 10 ppm.

[0041] Aspect 4. A wastewater recycling system consisting essentially of a series of processes, the series of processes comprising: directing a raw wastewater influent through a filtration device to separate solids from the wastewater influent, the filtration device comprising a self-cleaning filter, wherein at least a portion of the raw wastewater is sourced from an emulsion

polymerization process; subjecting the filtered wastewater influent to a chemical pretreatment process wherein a first oxidizing agent is introduced to the filtered wastewater influent to degrade any refractory chemical oxygen demand to a biodegradable chemical oxygen demand and then the oxidized wastewater influent is charged with a first additive to raise the pH to 10 or about 10 to form a precipitate in the oxidized wastewater influent; separating the precipitate from the oxidized wastewater influent to remove all settled particles and directing the separated wastewater influent through a bioreactor to aerobically reduce carbon present in the separated wastewater to provide a biologically treated wastewater, the bioreactor containing membrane modules submerged in an activated sludge; acidifying the biologically treated wastewater to convert bicarbonate or carbonate alkalinity to carbon dioxide gas, the carbon dioxide gas removed in an aeration buffer tank; directing the acidified wastewater influent through a water softening subsystem to remove any residual mineral content in the acidified wastewater;

introducing a second additive to increase the pH of the acidified wastewater and directing a feedstream of the resultant wastewater through a reverse osmosis unit, the wastewater pressurized to facilitate flow through a membrane of the reverse osmosis unit, wherein the wastewater as outputted from the reverse osmosis unit has a total solids content of less than 10 ppm.

[0042] Aspect 5. A wastewater recycling system comprising a series of processes, the series of processes consisting of: directing a raw wastewater influent through a filtration device to separate solids from the wastewater influent, the filtration device comprising a self-cleaning filter, wherein at least a portion of the raw wastewater is sourced from an emulsion

polymerization process; subjecting the filtered wastewater influent to a chemical pretreatment process wherein a first oxidizing agent is introduced to the filtered wastewater influent to degrade any refractory chemical oxygen demand to a biodegradable chemical oxygen demand and then the oxidized wastewater influent is charged with a first additive to raise the pH to 10 or about 10 to form a precipitate in the oxidized wastewater influent; separating the precipitate from the oxidized wastewater influent to remove all settled particles and directing the separated wastewater influent through a bioreactor to aerobically reduce carbon present in the separated wastewater to provide a biologically treated wastewater, the bioreactor containing membrane modules submerged in an activated sludge; acidifying the biologically treated wastewater to convert bicarbonate or carbonate alkalinity to carbon dioxide gas, the carbon dioxide gas removed in an aeration buffer tank; directing the acidified wastewater influent through a water softening subsystem to remove any residual mineral content in the acidified wastewater;

introducing a second additive to increase the pH of the acidified wastewater and directing a feedstream of the resultant wastewater through a reverse osmosis unit, the wastewater pressurized to facilitate flow through a membrane of the reverse osmosis unit, wherein the wastewater as outputted from the reverse osmosis unit has a total solids content of less than 10 ppm.

[0043] Aspect 6. A wastewater recycling system comprising a series of processes, the series of processes comprising: directing a raw wastewater influent through a filtration device to separate solids from the wastewater influent, the filtration device comprising a self-cleaning filter, wherein at least a portion of the raw wastewater is sourced from an emulsion polymerization process; subjecting the filtered wastewater influent to a chemical pretreatment process wherein a first oxidizing agent is introduced to the filtered wastewater influent to degrade any refractory chemical oxygen demand to a biodegradable chemical oxygen demand and then the oxidized wastewater influent is charged with a first additive to raise the pH to between 8 and 12 to form a precipitate in the oxidized wastewater influent; separating the precipitate from the oxidized wastewater influent to remove all settled particles and directing the separated wastewater influent through a bioreactor to aerobically reduce carbon present in the separated wastewater to provide a biologically treated wastewater, the bioreactor containing membrane modules submerged in an activated sludge; acidifying the biologically treated wastewater to convert bicarbonate or carbonate alkalinity to carbon dioxide gas, the carbon dioxide gas removed in an aeration buffer tank; directing the acidified wastewater influent through a water softening subsystem to remove any residual mineral content in the acidified wastewater; introducing a second additive to increase the pH of the acidified wastewater and directing a feedstream of the resultant wastewater through a reverse osmosis unit, the wastewater pressurized to facilitate flow through a membrane of the reverse osmosis unit, wherein the wastewater as outputted from the reverse osmosis unit has a total solids content of less than 10 ppm.

[0044] Aspect 7. The recycling system of any of aspects 1-6, wherein at least a portion of the raw wastewater is sourced from an emulsion polymerization process for acrylonitrile butadiene styrene.

[0045] Aspect 8. The recycling system of any of aspects 1-7, wherein the self-cleaning filter is configured to exclude particles greater than 1 mm in size.

[0046] Aspect 9. The recycling system of any of aspects 1-7, wherein the self-cleaning filter is configured to exclude particles greater than about 1 mm in size.

[0047] Aspect 10. The recycling system of any of aspects 1-7, wherein the self-cleaning filter is configured to exclude particles greater than 500 μπι in size.

[0048] Aspect 11. The recycling system of any of aspects 1-7, wherein the self-cleaning filter is configured to exclude particles greater than about 500 μιη in size. [0049] Aspect 12. The recycling system of any of aspects 1-11, wherein the first oxidizing agent comprises hydrogen peroxide or sodium persulfate.

[0050] Aspect 13. The recycling system of any of aspects 1-12, wherein the first additive comprises sodium hydroxide.

[0051] Aspect 14. The recycling system of any one of aspects 1-13, wherein sodium carbonate is added in addition to a first additive to facilitate formation of a calcium carbonate precipitate.

[0052] Aspect 15. The recycling system any of aspects 1-14, wherein a polyelectrolyte is added in addition to a first additive to facilitate formation of a precipitate.

[0053] Aspect 16. The recycling system of aspect any of aspects 1-15, wherein separating the precipitate comprises directing the oxidized wastewater influent through a clarifier and discarding any sludge collected in the clarifier.

[0054] Aspect 17. The recycling system of any of aspects 1-16, wherein the separated wastewater is cooled before the introduction of the separated wastewater into the bioreactor.

[0055] Aspect 18. The recycling system of any of aspects 1-17, wherein aeration tanks are disposed within the bioreactor to aerate the separated wastewater influent thereby initiating aerobic reduction of carbon present in the separated wastewater.

[0056] Aspect 19. The recycling system of any of aspects 1-18, wherein an anti-foam agent is added to the bioreactor.

[0057] Aspect 20. The recycling system of any of aspects 1-19, wherein a microbial nutrients agent is added to the bioreactor.

[0058] Aspect 21. The recycling system of any of aspects 1-20, wherein an excess of activated sludge is generated in the bioreactor.

[0059] Aspect 22. The recycling system of any of aspects 1-21, wherein the submerged membrane modules can be regenerated.

[0060] Aspect 23. The recycling system of any of aspects 1-22, wherein a second oxidizing agent comprises ozone, ultraviolet radiation, or hydrogen peroxide, or a combination thereof.

[0061] Aspect 24. The recycling system of any of aspects 1-23, wherein acidifying the biologically treated wastewater comprises introducing sulfuric.

[0062] Aspect 25. The recycling system of any of aspects 1-24, wherein the water softening subsystem comprises a resin bed.

[0063] Aspect 26. The recycling system of any of aspects 1-25, wherein the second additive comprises sodium hydroxide. [0064] Aspect 27. The recycling system of any of aspects 1-26, wherein the reverse osmosis unit comprises a cartridge filter housing through which the resultant wastewater is directed and then pressurized before entering a reverse osmosis membrane of the reverse osmosis unit.

[0065] Aspect 28. A method of purifying raw wastewater generated during an emulsion polymerization process for acrylonitrile butadiene styrene, the method comprising: directing a raw wastewater influent through a filtration device to separate solids from the wastewater influent, the filtration device comprising a self -cleaning filter, wherein at least a portion of the raw wastewater is sourced from an emulsion polymerization process; subjecting the filtered wastewater influent to a chemical pretreatment process wherein a first oxidizing agent is introduced to the filtered wastewater influent to degrade any refractory chemical oxygen demand to a biodegradable chemical oxygen demand and then the oxidized wastewater influent is charged with a first additive to raise the pH to 10 or about 10 to form a precipitate in the oxidized wastewater influent; separating the precipitate from the oxidized wastewater influent to remove all settled particles and directing the separated wastewater influent through a bioreactor to aerobically reduce carbon present in the separated wastewater to provide a biologically treated wastewater, the bioreactor containing membrane modules submerged in an activated sludge; acidifying the biologically treated wastewater to convert bicarbonate or carbonate alkalinity to carbon dioxide gas, the carbon dioxide gas removed in an aeration buffer tank; directing the acidified wastewater influent through a water softening subsystem to remove any residual mineral content in the acidified wastewater; introducing a second additive to increase the pH of the acidified wastewater and directing a feedstream of the resultant wastewater through a reverse osmosis unit, the wastewater pressurized to facilitate flow through a membrane of the reverse osmosis unit, wherein the wastewater as outputted from the reverse osmosis unit has a total solids content of less than 10 ppm or less than about 10 ppm.

[0066] Aspect 29. A method of purifying raw wastewater generated during an emulsion polymerization process for acrylonitrile butadiene styrene, the method consisting essentially of: directing a raw wastewater influent through a filtration device to separate solids from the wastewater influent, the filtration device comprising a self-cleaning filter, wherein at least a portion of the raw wastewater is sourced from an emulsion polymerization process; subjecting the filtered wastewater influent to a chemical pretreatment process wherein a first oxidizing agent is introduced to the filtered wastewater influent to degrade any refractory chemical oxygen demand to a biodegradable chemical oxygen demand and then the oxidized wastewater influent is charged with a first additive to raise the pH to 10 or about 10 to form a precipitate in the oxidized wastewater influent; separating the precipitate from the oxidized wastewater influent to remove all settled particles and directing the separated wastewater influent through a bioreactor to aerobically reduce carbon present in the separated wastewater to provide a biologically treated wastewater, the bioreactor containing membrane modules submerged in an activated sludge; acidifying the biologically treated wastewater to convert bicarbonate or carbonate alkalinity to carbon dioxide gas, the carbon dioxide gas removed in an aeration buffer tank; directing the acidified wastewater influent through a water softening subsystem to remove any residual mineral content in the acidified wastewater; introducing a second additive to increase the pH of the acidified wastewater and directing a feedstream of the resultant wastewater through a reverse osmosis unit, the wastewater pressurized to facilitate flow through a membrane of the reverse osmosis unit, wherein the wastewater as outputted from the reverse osmosis unit has a total solids content of less than 10 ppm or less than about 10 ppm.

[0067] Aspect 30. A method of purifying raw wastewater generated during an emulsion polymerization process for acrylonitrile butadiene styrene, the method comprising: directing a raw wastewater influent through a filtration device to separate solids from the wastewater influent, the filtration device comprising a self -cleaning filter, wherein at least a portion of the raw wastewater is sourced from an emulsion polymerization process; subjecting the filtered wastewater influent to a chemical pretreatment process wherein a first oxidizing agent is introduced to the filtered wastewater influent to degrade any refractory chemical oxygen demand to a biodegradable chemical oxygen demand and then the oxidized wastewater influent is charged with a first additive to raise the pH to 10 or about 10 to form a precipitate in the oxidized wastewater influent; separating the precipitate from the oxidized wastewater influent to remove all settled particles and directing the separated wastewater influent through a bioreactor to aerobically reduce carbon present in the separated wastewater to provide a biologically treated wastewater, the bioreactor containing membrane modules submerged in an activated sludge; acidifying the biologically treated wastewater to convert bicarbonate alkalinity to carbon dioxide gas, the carbon dioxide gas removed in an aeration buffer tank; directing the acidified wastewater influent through a water softening subsystem to remove any residual mineral content in the acidified wastewater; introducing a second additive to increase the pH of the acidified wastewater and directing a feedstream of the resultant wastewater through a reverse osmosis unit, the wastewater pressurized to facilitate flow through a membrane of the reverse osmosis unit, wherein the wastewater as outputted from the reverse osmosis unit has a total solids content of less than 10 ppm or less than about 10 ppm.

[0068] Aspect 31. A method of purifying raw wastewater generated during an emulsion polymerization process for acrylonitrile butadiene styrene, the method comprising: directing a raw wastewater influent through a filtration device to separate solids from the wastewater influent, the filtration device comprising a self -cleaning filter, wherein at least a portion of the raw wastewater is sourced from an emulsion polymerization process; subjecting the filtered wastewater influent to a chemical pretreatment process wherein a first oxidizing agent is introduced to the filtered wastewater influent to degrade any refractory chemical oxygen demand to a biodegradable chemical oxygen demand and then the oxidized wastewater influent is charged with a first additive to raise the pH to 10 or about 10 to form a precipitate in the oxidized wastewater influent; separating the precipitate from the oxidized wastewater influent to remove all settled particles and directing the separated wastewater influent through a bioreactor to aerobically reduce carbon present in the separated wastewater to provide a biologically treated wastewater, the bioreactor containing membrane modules submerged in an activated sludge; acidifying the biologically treated wastewater to convert carbonate alkalinity to carbon dioxide gas, the carbon dioxide gas removed in an aeration buffer tank; directing the acidified wastewater influent through a water softening subsystem to remove any residual mineral content in the acidified wastewater; introducing a second additive to increase the pH of the acidified wastewater and directing a feedstream of the resultant wastewater through a reverse osmosis unit, the wastewater pressurized to facilitate flow through a membrane of the reverse osmosis unit, wherein the wastewater as outputted from the reverse osmosis unit has a total solids content of less than 10 ppm or less than about 10 ppm.

[0069] Aspect 32. The recycling system of any of aspects 1-6, wherein the first additive comprises sodium hydroxide or a combination of sodium hydroxide and sodium carbonate to facilitate formation of a calcium carbonate precipitate.

[0070] Aspect 33. The recycling system of any of aspects 1-6, wherein the first additive comprises sodium hydroxide or a combination of sodium hydroxide and a polyelectrolyte to facilitate formation of a calcium carbonate precipitate.

[0071] Aspect 34. The recycling system of any of aspects 1-19, wherein an anti-foam agent, or a microbial nutrients agent, or a combination thereof, is added to the bioreactor.

[0072] Aspect 35. A method of purifying raw wastewater generated during an emulsion polymerization process for acrylonitrile butadiene styrene, the method consisting of: directing a raw wastewater influent through a filtration device to separate solids from the wastewater influent, the filtration device comprising a self -cleaning filter, wherein at least a portion of the raw wastewater is sourced from an emulsion polymerization process; subjecting the filtered wastewater influent to a chemical pretreatment process wherein a first oxidizing agent is introduced to the filtered wastewater influent to degrade any refractory chemical oxygen demand to a biodegradable chemical oxygen demand and then the oxidized wastewater influent is charged with a first additive to raise the pH to 10, or to about 10, to form a precipitate in the oxidized wastewater influent; separating the precipitate from the oxidized wastewater influent to remove all settled particles and directing the separated wastewater influent through a bioreactor to aerobically reduce carbon present in the separated wastewater to provide a biologically treated wastewater, the bioreactor containing membrane modules submerged in an activated sludge; acidifying the biologically treated wastewater to convert bicarbonate or carbonate alkalinity to carbon dioxide gas, the carbon dioxide gas removed in an aeration buffer tank; directing the acidified wastewater influent through a water softening subsystem to remove any residual mineral content in the acidified wastewater; introducing a second additive to increase the pH of the acidified wastewater and directing a feedstream of the resultant wastewater through a reverse osmosis unit, the wastewater pressurized to facilitate flow through a membrane of the reverse osmosis unit, wherein the wastewater as outputted from the reverse osmosis unit has a total solids content of less than 10 ppm or less than about 10 ppm.

[0073] Aspect 36. A method of purifying raw wastewater generated during an emulsion polymerization process for acrylonitrile butadiene styrene, the method comprising: directing a raw wastewater influent through a filtration device to separate solids from the wastewater influent, the filtration device comprising a self -cleaning filter, wherein at least a portion of the raw wastewater is sourced from an emulsion polymerization process; subjecting the filtered wastewater influent to a chemical pretreatment process wherein a first oxidizing agent is introduced to the filtered wastewater influent to degrade any refractory chemical oxygen demand to a biodegradable chemical oxygen demand and then the oxidized wastewater influent is charged with a first additive to raise the pH to between 9 and 11 to form a precipitate in the oxidized wastewater influent; separating the precipitate from the oxidized wastewater influent to remove all settled particles and directing the separated wastewater influent through a bioreactor to aerobically reduce carbon present in the separated wastewater to provide a biologically treated wastewater, the bioreactor containing membrane modules submerged in an activated sludge; acidifying the biologically treated wastewater to convert bicarbonate or carbonate alkalinity to carbon dioxide gas, the carbon dioxide gas removed in an aeration buffer tank; directing the acidified wastewater influent through a water softening subsystem to remove any residual mineral content in the acidified wastewater; introducing a second additive to increase the pH of the acidified wastewater and directing a feedstream of the resultant wastewater through a reverse osmosis unit, the wastewater pressurized to facilitate flow through a membrane of the reverse osmosis unit, wherein the wastewater as outputted from the reverse osmosis unit has a total solids content of less than 10 ppm or less than about 10 ppm.

[0074] Aspect 37. A wastewater recycling system comprising a series of processes, the series of processes comprising: directing a raw wastewater influent through a filtration device to separate solids from the wastewater influent, the filtration device comprising a self-cleaning filter, wherein at least a portion of the raw wastewater is sourced from an emulsion

polymerization process; subjecting the filtered wastewater influent to a chemical pretreatment process wherein a first oxidizing agent is introduced to the filtered wastewater influent to degrade any refractory chemical oxygen demand to a biodegradable chemical oxygen demand and then the oxidized wastewater influent is charged with a first additive to raise the pH to between 8 and 12 to form a precipitate in the oxidized wastewater influent; separating the precipitate from the oxidized wastewater influent to remove all settled particles and directing the separated wastewater influent through a bioreactor to aerobically reduce carbon present in the separated wastewater to provide a biologically treated wastewater, the bioreactor containing membrane modules submerged in an activated sludge; acidifying the biologically treated wastewater to convert bicarbonate or carbonate alkalinity to carbon dioxide gas, the carbon dioxide gas removed in an aeration buffer tank; directing the acidified wastewater influent through a water softening subsystem to remove any residual mineral content in the acidified wastewater; introducing a second additive to increase the pH of the acidified wastewater and directing a feedstream of the resultant wastewater through a reverse osmosis unit, the wastewater pressurized to facilitate flow through a membrane of the reverse osmosis unit, wherein the wastewater as outputted from the reverse osmosis unit has a total solids content of less than 10 ppm.

EXAMPLES

[0075] Detailed embodiments of the present disclosure are disclosed herein; it is to be understood that the disclosed embodiments are merely exemplary of the disclosure that may be embodied in various forms. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limits, but merely as a basis for teaching one skilled in the art to employ the present disclosure. The specific examples below will enable the disclosure to be better understood. However, they are given merely by way of guidance and do not imply any limitation.

[0076] In an example, raw waster is created during the production of acrylonitrile butadiene styrene (ABS). The average flow of the water is 100 m /hr for a daily average flow of 2,400 CMD. The pH of the water is about 2 to 3. The BOD in the water amounted to about 600 ppm. The COD amounts to about 1,800 ppm. The sulfates amounted to about 2,100 ppm. The phosphorous amounts to about 80 ppm. The total dissolved solids TDS amounts to about 2,400 ppm. The total suspended solids TSS amounts to about 1,000 ppm. Ca+Mg amounted to about 100 ppm. Na+K amounted to about 50 ppm. Alkalinity amounts to about 110 ppm as CaC03. At the end of the production process the water is at about 60 degrees Celsius.

[0077] A stream of raw wastewater was first filtered through a self-cleaning filtration system. The filtered wastewater was then treated with hydrogen peroxide or sodium persulfate. The wastewater was chemically neutralized with sodium hydroxide which caused the formation of precipitates in the solution and increased the pH to about 10. Sodium carbonate was added. Overflow was directed to a clarifier to remove settled particles. The resultant wastewater was then treated through the membrane bioreactor system which separated the wastewater filtrate and sludge. The wastewater filtrate was then acidified to convert all bicarbonate or carbonate alkalinity to carbon dioxide and the wastewater directed through the water softener for complete removal of minerals present in the wastewater. Sodium hydroxide was then used to increase the pH of the resultant wastewater to about 10. The wastewater was then filtered through a cartridge filter of the reverse osmosis system. A high pressure pump then directed the filtered waste water to the reverse osmosis membranes at high pressure. Purified wastewater was then collected upon passing through the membrane.

[0078] Table 2 presents the water analysis for the wastewater recycled according to the system of processes.

Table 2. Wastewater analysis after undergoing processes of the recycling system.

[0079] The resultant water had a pH between 8.3-8.6. The temperature is less than 50 degrees Celsius. The total of dissolved solids is less than 110 mg/1. The calcium (as CaC(¾) in the water is less than 78 mg/1. The sodium (as Na) is less than 30 mg/1. The total alkalinity (as CaCC ) has decreased from the raw wastewater value of about 110 ppm to less than 80 mg/1. The sulfate content has decreased from 2,100 ppm to less than 80 mg/1. The Chloride (as CI) is less than 30 mg/1). The iron (as Fe) content is less than .06 mg/1. The mineral silica is less than 0.52 mg/1. The residual chlorine is around 0.32 (or 1.0 mg/1). There are no suspended solids, compared to the raw wastewater total suspended solids content of 1,000 ppm. The turbidity, which corresponds to the cloudiness of the water attributed to particles, is less than 1.0 nephelometric turbidity unit (NTU).

[0080] About 10 % of the incoming water is discharged from the reverse unit as a concentrated stream that is disposed of to an industrial wastewater treatment system or receiving body of water. Therefore, approximately 90 % of the incoming water is available for recycle inside the ABS unit.

DEFINITIONS

[0081] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. Although any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present disclosure, example methods and materials are now described. It is to be understood that the terminology used herein is for the purpose of describing particular aspects only and is not intended to be limiting.

[0082] As used in the specification and in the claims, the term "comprising" can include the embodiments "consisting of and "consisting essentially of." Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. In this specification and in the claims which follow, reference will be made to a number of terms which shall be defined herein.

[0083] As used in the specification and the appended claims, the singular forms "a," "an" and "the" include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to "a ketone" includes mixtures of two or more ketones.

[0084] Ranges can be expressed herein as from "about " one particular value, and/or to "about " another particular value. When such a range is expressed, another aspect includes from the one particular value and/or to the other particular value. Similarly, when values are expressed as approximations, by use of the antecedent 'about ,' it will be understood that the particular value forms another aspect. It will be further understood that the endpoints of each of the ranges are significant both in relation to the other endpoint, and independently of the other endpoint. It is also understood that there are a number of values disclosed herein, and that each value is also herein disclosed as "about " that particular value in addition to the value itself. For example, if the value "10" is disclosed, then "about 10" is also disclosed. It is also understood that each unit between two particular units are also disclosed. For example, if 10 and 15 are disclosed, then 11, 12, 13, and 14 are also disclosed.

[0085] Each of the materials disclosed herein are either commercially available and/or the methods for the production thereof are known to those of skill in the art.