222results about How to "Stable up-to-standard discharge" patented technology

The invention discloses a method for pretreating fly ash of domestic refuse incineration through cooperative disposal of cement kilns, which belongs to the technical field of solid waste treatment and disposal. The method comprises a fly-ash washing-dechlorination stage, a washed-ash dehydration stage, a supernatant treatment stage and a kiln-entering calcination stage, wherein sulfuric acid serving as neutralizer is added to supernatant or removed filtrate in order to neutralize the supernatant or the removed filtrate and allows pH to reach a range between 6 and 9, and then dithiocarbamate-type derivatives serving as a heavy metal chelating agent and a polyacrylamide flocculating agent are added in turn to guarantee the precipitation effect of heavy metal ions. Sulfuric acid neutralization and heavy metal precipitation are performed on eluate to ensure that washing liquid can reach discharge standards. The method utilized to treat fly ash has the advantages of saving raw materials of the cement industry, effectively fixing heavy metal, thoroughly burning down dioxin, disposing of fly ash safely, economically and conveniently and achieving environmental, economic and social benefits.

The invention relates to a process for treating high-concentration pyridine waste water, which comprises the following steps of: regulating raw water of waste water to be acidic, and treating the raw water in electro-catalytic oxidation equipment; leading effluent to a micro-electrolysis device for treatment under the condition of maintaining the acidity and oxygen enrichment of the waste water; regulating the effluent to be meta-alkalescent, and adding chemicals to perform coagulating sedimentation; and controlling the salinity of the waste water to be below 2 percent, and performing biochemical treatment in an anaerobic hydrolyzing device and a pressurizing biological contact oxidation device, so that the effluent reaches the conventional first-level standards for sewage discharge. Due to the adoption of a physico-chemical treatment process serving electro-catalytic oxidation as a core, pyridine pollutants can be decomposed effectively, the toxicity of the waste water can be reduced, and the biodegradability of the waste water can be improved; for biochemical treatment is realized by a combination process of anaerobic hydrolysis and pressurizing biological contact oxidation, the organic loads, treatment efficiency and salt-tolerant capacity of the biochemical treatment are improved; and the process has the characteristics of high impact load resistant capacity, good treatment effect and low operating cost, and the treated high-concentration pyridine waste water can reach the standard stably before discharge.

The invention discloses a method for preparing gypsum by free sulfuric acid in titanium dioxide wastewater. The method comprises the following steps of: a: collecting acidic wastewater produced by a sulfuric acid method in a production process of titanium dioxide in an adjusting tank; b: transporting the acidic wastewater in the adjusting tank into a reaction tank, and at the same time, adding limestone mineral powder slurry ground by grinding equipment in the reaction tank to neutralize free sulfuric acid; c: transporting the prepared gypsum slurry into a precipitation tank, and fully dehydrating to prepare crude gypsum; d: washing the prepared crude gypsum with a little clean water, and finally washing with a little lime milk solution; and e: secondarily squeezing the washed crude gypsum and fully dehydrating to prepare the gypsum product. The method has the beneficial effects that the gypsum is prepared by free sulfuric acid in the wastewater, stable emission standard of the wastewater can be guaranteed, and solid slag produced by the sulfuric acid method in a wastewater processing technology of titanium dioxide becomes treasure from waste, so that in the whole processing process, the output of solid waste is greatly reduced, and therefore, the cost of wastewater processing is greatly reduced.

The invention discloses an optimization method and an optimization system of SCR denitrification intelligent ammonia injection based on soft measurement and predictive control. The method comprises the following steps: firstly, establishing an entrance nitrogen oxide concentration model based on operation data; then utilizing the model and currently-collected operation data to obtain a predicted value; secondly, calculating the ammonia injection amount at the current operation condition as a feedforward signal according to an entrance nitrogen oxide concentration predicted value and transmitting the feedforward signal of the ammonia injection amount to an SCR denitrification system; thirdly, measuring a measured value of exit nitrogen oxide concentration of a coal-fired generation unit combustion system, making deviation between the measured value and an entrance nitrogen oxide concentration set value and inputting a difference value into a prediction controller, obtaining a feedback control signal of the ammonia injection amount based on the deviation and transmitting the feedback control signal to the SCR denitrification system by a prediction controller; fourthly, controlling the ammonia injection amount of an SCR denitrification reactor according to the feedforward signal of the ammonia injection amount and the feedback control signal of the ammonia injection amount by theSCR denitrification system. The system disclosed by the invention has the advantages of higher response rate, lower investment, short transformation period and the like.

The invention relates to a drainage network pollutant emission tracing method and device. The device comprises water quality monitoring modules, power supply devices, signal transmitting systems, a cloud service platform, and a mobile terminal; a plurality of water quality monitoring modules are respectively arranged at all monitoring points of the drainage network, a plurality of power supply devices are arranged, respectively connected with the corresponding water quality monitoring modules and used for supplying power for the corresponding water quality monitoring modules; a plurality of signal transmitting systems are arranged, connected with the corresponding water quality monitoring modules and used for sending data collected by the water quality monitoring modules to the outside; the cloud service platform is connected with the signal transmitting systems and is used for receiving the data collected by the water quality monitoring modules and processing the data to obtain an early warning value, performing tracing in combination with the position information of the water quality monitoring modules when the early warning value is exceeded, and giving an alarm in time; and themobile terminal is connected with the cloud service platform and used for receiving alarm information and water quality information. Compared with the prior art, the method and the device have the advantages that multi-node and multi-parameter real-time monitoring can be realized and the early warning can be carried out, so that pollutant emission of the industrial pollution source drainage network can be conveniently traced.

The invention relates to treatment of organic-substance-containing wastewater having high salt content and particularly relates to a method for treating wastewater by virtue of multi-stage catalytic oxidation, micro electrolysis and multi-effect evaporation. According to the method, by reasonably utilizing steam and heat generated by an evaporator, better salt removal effect is achieved so that the subsequent biological treatment can be more efficient.

The invention discloses a VOC decomposition composite-purifying processing apparatus and a method. the apparatus comprises a tower body, a circulation water pool for holding tap water, and a composite decomposition water pool for holding a spraying liquid; the tower body is inside successively provided with an air intake, a first liquid collector, a first filler layer, a first liquid distributor, a second liquid collector, a second filter layer, a second liquid distributor, a gas-liquid separator and an air outlet. By employing the provided VOC decomposition composite-purifying processing apparatus for processing VOC exhaust gas, the following advantages are provided: the purification effect is stable and reaches the standard, one-time investment is much less than that of a conventional active carbon technology, and the operating cost is reduced by 90% or more compared with that of a conventional active carbon technology.

The invention discloses a synchronous denitrification and dephosphorization sewage treatment device for an immobilized microorganism CASS (cyclic activated sludge system). The synchronous denitrification and dephosphorization sewage treatment device comprises a pond. A water inlet tube is arranged at one end of the pond, a water outlet tube is arranged at the other end of the pond, a hollow gridding reaction box is disposed in the pond, immobilized microorganism carriers are arranged in the hollow gridding reaction box, and an aeration device is arranged at the bottom of the pond. The synchronous denitrification and dephosphorization sewage treatment device aims to overcome shortcomings in the prior art, is simple in structure, and is efficient and stable.

The invention relates to an ammonia tail gas recycling method and system. The method comprises condensing tail gas containing ammonia so as to obtain dilute ammonia water and condensed ammonia tail gas; distilling the dilute ammonia water to obtain ammonia gas, water and distilled liquid; and subjecting the condensed ammonia tail gas and the ammonia gas to first spraying absorption by use of low-concentration ammonia chloride solution to obtain first spray ammonia nitrogen solution and first spray residual ammonia tail gas, wherein the ammonia nitrogen concentration in the ammonia nitrogen solution is not lower than 70g / L. With the inventive method, ammonia-containing tail gas can be effectively recycled.

The invention provides a novel emulsion wastewater treatment process. The process comprises a regulating reservoir, an accident pool, a demulsification device, a paper strip filter, a ceramic film filter, an ozonolysis tank, a hydrolysis acidification pool, an aeration tank, a settling pond, a quartz sand filter and a water discharge pool. Aiming at the characteristics of emulsion water quality, physicochemical treatment units and biological treatment units are reasonably combined, and the process has the advantages of short and compact process procedures, high treatment efficiency, low energy consumption, long service life of a film component and the like.

The invention provides an efficient energy-saving type multi-mode enhanced denitrification sewage treatment system. The system comprises an anaerobic zone, an anoxic zone, an aeration zone I, a maneuvering zone, an aeration zone II, a rear anoxic zone and an aerobic zone which are connected in sequence, wherein a sludge regeneration area is arranged at the upper part of the anaerobic area; two water outlets are formed in the anaerobic zone and are respectively connected with the sludge regeneration zone and the anoxic zone; gates are arranged on the two water outlets to control the flow direction of water in the anaerobic zone; the aeration zone I and the aeration zone II are aerobic tanks or aeration anoxic tanks; and the maneuvering zone is an aerobic tank, an anoxic tank or an aerationanoxic tank. The system adopts a novel sewage treatment process developed on the basis of a traditional multi-stage AO process, and the core of the process is to combine an aeration anoxic process anda multi-stage AO process together, so that short-cut denitrification can be realized; and a plurality of water inlet points, multi-section backflow and precise aeration system control are arranged, so that sewage treatment systems in various modes can be formed, and different water outlet requirements can be met.

The invention discloses a tanning synthetic wastewater treatment system and treatment method, and belongs to the technical field of industrial wastewater treatment. The treatment system comprises a regulating tank, an anaerobic tank, a preaeration tank, a primary sedimentation tank, a first-level denitrification tank, an aerobic tank, a secondary sedimentation tank, a second-level denitrification tank, a coagulative precipitation tank, a Fenton oxidation tank and a biological aerated filter. According to the wastewater treatment method, tanning synthetic wastewater is treated by combining biochemical treatment with deep treatment, the wastewater treatment efficiency is high, and effluent is stable in quality and can be directly drained; in addition, the wastewater treatment cost is significantly reduced, and therefore the method is suitable for large-scale application and popularization and has the wide application prospect.

The invention discloses a method for processing city household garbage leachate. Aiming at the garbage leachate's characteristics of high ammonia nitrogen content and difficult biodegradation, people develop the processing method by combining and optimizing the following technologies: lime pretreatment, gas-film acid absorption, high efficient multi-grade AO biochemical treatment, and modified carbon absorption. The processing method comprises the following steps: subjecting the garbage leachate to a foam separation process so as to reduce the grease and surfactant content in the garbage leachate; adding lime into the garbage leachate so as to adjust the pH value of the garbage leachate and convert the ammonia nitrogen into a free state; subjecting the garbage leachate to processes of micro-filtration and ultrafiltration so as to eliminate macromolecular organic substances, then subjecting the garbage leachate to a gas-film acid absorption treatment so as to effectively eliminate the nitrogen ammonia with a high concentration in the garbage leachate to meet the requirements of biochemical treatment, subjecting the garbage leachate to go through an AO biochemical treatment system so as to further eliminate the pollutants such as total nitrogen, ammonia nitrogen, COD, BOD, and the like in the garbage leachate, so that after the processes mentioned above, only organic matters that are difficult to degrade and soluble are left in the garbage leachate, adopting modified carbon as an absorbent and a counter-current multi-grade absorption technology to effectively eliminate the organic matters difficult to degrade in the garbage leachate to make the garbage leachate meet the national discharging standard, and finally discharging the qualified garbage leachate.

The invention relates to an aerobic-anoxic integration AO membrane bioreactor and aims to effectively solve the problems of backflow of nitrification liquor in the existing AO process, large occupied space, complicated operation and high operation cost. According to the technical scheme, a sludge area is arranged at the bottom of a shell; a shell inner cavity above the sludge area is divided into an aerobic area, a flow guide area and an anoxic precipitation area which are successively arranged along a horizontal direction; the bottoms of the aerobic area, the flow guide area and the anoxic precipitation area are communicated with the upper part of the sludge area; an aeration pipe is arranged in the aerobic area; an overflowing opening is formed in the upper part of a first partition plate between the aerobic area and the flow guide area; a ceramic membrane component is arranged in the anoxic precipitation area; a water discharging pipeline stretching out of the shell is mounted on the ceramic membrane component. Through the aerobic-anoxic integration AO membrane bioreactor, the aerobic-anoxic integration can be achieved; the occupied area is small; returning devices do not need to be additionally arranged; the process is simplified; the stable and up-to-standard emission of the wastewater can be achieved; the aerobic-anoxic integration AO membrane bioreactor is convenient to use and excellent in effect, and has significant social and economic benefits.

The invention discloses a method for pretreating coal chemical industry production waste water and recycling resources of the waste water. According to the technical scheme, the method comprises the following steps of: (1) performing rectification, deacidification and deamination, namely feeding the coal chemical industry waste water into a rectification, deacidification and deamination tower, transferring ammonia and carbon dioxide in the waste water from a liquid phase to a gas phase, and respectively recycling 15 to 20 percent of ammonia water and ammonium bicarbonate; and (2) performing complexing extraction and recycling phenolic substances, namely adjusting the pH of the rectified residual solution in a kettle to be less than 3 by acid, adding a prepared oil phase according to a certain proportion, performing complexing extraction, after extraction is balanced, obtaining a load oil phase and pretreated waste water, performing reverse extraction on the load oil phase by sodium hydroxide solution serving as an extraction agent to obtain a concentrated sodium phenolate solution and a regenerated oil phase, acidifying the sodium phenolate to obtain crude phenol, and recycling the regenerated oil phase. Compared with the prior art, the method has the advantages that the technical flow is simple; the equipment investment is small, the energy consumption is low, the efficiency is high, and the phenol recycling rate is high; harmlessness and reclamation of the waste water are realized; and the method is obvious in economical and environmental benefits.

The invention discloses a method for treating high-salt content and refractory oil exploitation wastewater, which specifically comprises the following steps of acidifying the high-salt content, high-oil content and refractory oil exploitation wastewater treated by a natural settling coarse graining efficient coalescence separation process, an air floatation process and a coagulating settling process by using an acid material, and adjusting the pH value of the beneficiation wastewater; sequentially adding a proper amount of proper ferrous sulfate and a small amount of hydrogen peroxide to form an efficient oxidant Fenton reagent; neutralizing with an alkaline material; separating the floc with a sedimentation tank; finally, reducing the content of the COD (chemical oxygen demand) in the wastewater through active carbon adsorption. The treated wastewater reaches the national standard of Integrated Wastewater Discharge Standard of Liaoning (DB21 / 1627-2008). With simple processes, the method disclosed by the invention can remove the suspended particles and organic matters left in the wastewater, needs relatively small equipment and space, and can better solve the problem in deep purification of the high-salt content and refractory oil exploitation wastewater.

The invention relates to a sewage treatment method for straw pulp papermaking. In order to solve the shortcomings of high operating cost and incomplete extraction of black liquor in the prior art, a sewage treatment method with low operating cost and capable of meeting discharge standards is provided. Including sending straw pulp papermaking raw materials into steaming balls for cooking to make raw pulp; the raw pulp is extracted through extrusion equipment three times to extract black liquor; the raw pulp that has extracted black liquor is sent to the pulping process for pulping, and the output The white water collects pulp fibers through an inclined mesh filter device, and the filtered white water enters a sump; adding flocculant to the sump, pumping it into the ultra-efficient shallow air flotation device through a pump, and simultaneously aerating and adding a coagulant; The scum collected by the effective shallow air flotation device, the scum is stirred into the sludge tank through the pulp thickening tank and the pulp tank, and the remaining clear water can be directly discharged or reused. The method has the advantages of high extraction rate of papermaking black liquor, small investment in middle stage water treatment, low operation cost of the whole technological process, thorough treatment, and stable discharge up to standard.

The invention discloses a multifunctional solid waste treatment device. The multifunctional solid waste treatment device comprises a pyrolysis gasifier. The pyrolysis gasifier comprises a gasifier body and a smoke drying box. A combustible gas storage box is arranged on the top of the gasifier body and communicated with the bottom of the gasifier body. A combustible gas delivery pipe is arranged on the upper portion of the gasifier body and connected with a condensation device, and the condensation device is connected with the combustible gas storage box. A smoke internal delivery pipe is arranged on the lower portion of the gasifier body, the smoke drying box is connected with a waste heat boiler connected with a smoke washing system, and the waste heat boiler is connected with a sludge drying device. The smoke washing system is connected with a sewage pool and a chimney, and the condensation device is connected with the sewage pool. The sewage pool is connected with a tar-water separation system capable of separating tar and water. The invention further provides a solid waste treatment method. By means of the device and the method, solid waste can be completely treated, combustion is complete, smoke is exhausted after reaching the standard, and meanwhile sludge treatment capacity is achieved.

The invention belongs to the technical field of wastewater treatment, in particular to amethod for treating industrial wastewater containing hexamethylenediamine by sequentially carrying out anaerobic biological treatment, hypoxia treatment, aerobic treatment and drainage to wastewater. The invention has simple process, low operation cost and good wastewater treatment effect, can stably reach the emission standard of chemical industrial wastewater containing the hexamethylenediamine so that various indexes of dischage water stably reach or exceed the A-catalog indexes of national first-order discharge water.

The invention discloses a method for recycling pyridine from pyridine wastewater through the liquid membrane separation technology. The toxic pollutant pyridine can be removed while the resource recovery can be realized. The method comprises the following steps: (1) preparing emulsion; (2) performing liquid membrane extraction; and (3) performing demulsification. Particularly, the method is as follows: the oil phase containing surfactant, membrane solvent and additive and dilute sulphuric acid are used to prepare emulsion under high speed shearing; the emulsion is dispersed in the wastewater with pyridine for mass transfer and extraction, the pyridine in the wastewater enters the liquid membrane phase, electrostatic demulsification is performed to generate pyridine sulfate which can be used in the production technology. In the process, the pyridine removal rate is more than 99% and the pyridine recovery rate is more than 90%. By adopting the method, the requirement that the emissions of the pyridine pollutants in wastewater meet the standards can be effectively realized. The method has obvious environmental benefit and economic benefit.

The invention provides an urban sewage treatment method and system. The method is used in the sewage treatment system. The sewage treatment system comprises a sewage regulating tank, a coarse grid, afine grid, a grit chamber, a biochemical tank, a secondary sedimentation tank and a disinfecting tank which are sequentially communicated. The biochemical tank is provided with an EBR filler, a lifting high-efficiency aeration system and a carbon source dosing system. The sewage flows into the coarse grid after being treated by the regulating tank, then flows into the fine grid with suspended solids intercepted by the coarse grid, then flows into the grit chamber with suspended solids intercepted by the fine grid, then flows into the biochemical tank after subjected to grit disposal, then flows into the secondary sedimentation tank after treated by the biochemical tank, then flows into the disinfecting tank after treated by the secondary sedimentation tank and flows into a clean water section after subjected to disinfection treatment by the disinfecting tank. By means of transformation of the treatment process of the traditional urban sewage treatment plant and setting of the biochemical tank, the sewage discharge can reach the class IV water body standard comprehensively and is enhanced to the class IV water body standard comprehensively.

The invention discloses a recycling treatment method of dye wastewater and belongs to the technical field of wastewater treatment. The method includes the steps of firstly, filtering; secondly, performing primary adsorption; thirdly, neutralizing; fourthly, performing secondary adsorption; fifthly, performing low-temperature catalytic oxidization; sixthly, performing concentration and evaporation;sixthly, performing biochemical treatment. The recycling treatment method has the advantages that residual dye in the wastewater and catalysts and salt in the wastewater can be recycled, wastewater recycling is achieved, a good wastewater treatment effect is achieved, and stable up-to-standard emission is achieved; meanwhile, the biochemical performance of the wastewater can be increased greatly,the stable operation of a follow-up biochemical system is guaranteed, and solid waste and secondary environment pollution are avoided completely.

The invention relates to treatment of organic waste water, in particular to a method for treating waste water in a multi-stage catalytic oxidation and microelectrolysis method, which includes comprises the following steps: pretreatment, aeration acidification, microelectrolysis, first-level catalytic oxidation treatment, aeration reaction, primary sedimentation, secondary catalytic oxidation treatment and secondary sedimentation. The COD index of treated waste water is 100-300mg / L. The method has the advantages of being high in reaction speed, simple in process flow, long in service life, less in investment cost, convenient to operate and maintain, low in operation cost and stable in treatment effect.

A process for treating the sewage generated by making paper with straw pulp includes such steps as preimmersing by alkali method, adding activating agent prepared from anthraquinone derivative, sodium alkylphenylsulfonate and epoxy ethane, fast low-temp digestion, adding 5 kinds of flocculant sequentially for separation, flocculating, decoloring, decomposing lignin and depositing, anaerobic digestion, aerobic aerating, cleaning by biomembrane, and dewatering dregs to obtain fertilizer.

The invention belongs to the field of chemical wastewater treatment of the petrochemical industry and particularly relates to an efficient treatment combination process of acrylonitrile wastewater. The combination process comprises: (1) acrylonitrile production wastewater enters a catalytic oxidation tower for catalytic hydrogen peroxide oxidation treatment; (2) water discharged form the catalytic oxidation tower and factory domestic sewage enter a biochemical treatment system after full mixing; the biochemical treatment system sequentially comprises an anaerobic hydrolysis tank, an anoxia tank and an MBR tank; (3) the biochemical treatment system adopts a membrane separation technique for treatment; partial concentrated solution flows back; the acrylonitrile production wastewater is wastewater produced by acrylonitrile device wastewater after four-effect evaporation and steam stripping; the temperature is 50 DEG C-80 DEG C; the hydraulic retention time in the catalytic oxidation tower is 30-120 min. According to the efficient treatment combination process of acrylonitrile wastewater, the microorganism poison inhibition effect of the biochemical treatment system microorganism can be reduced, the wastewater biodegradability is improved, the treatment load and the treatment cost of the catalytic oxidation tower are reduced, the denitrification effect is guaranteed, and the membrane service life is prolonged.

A pretreating process or reclaiming the sewage generated by printing and dyeing chemical fibres includes such steps as using acid to regulate pH=2.5-5.0, adding flocculant, stirring, and solid-liquid separating. The process can remove 75-90% CODcr in sewage.

The invention belongs to the field of pesticide production waste water treatment and discloses a 2,4-D pesticide production waste water pretreatment method. 2,4-dichlorophenol and 2,4-D are recovered from the waste water by a liquid membrane separation technique, so harmful pollutants are removed and reclamation is realized at the same time. The 2,4-D pesticide production waste water pretreatment method mainly comprises the following steps of: 1) preparing emulsion; 2) performing liquid membrane extraction; and 3) breaking the emulsion. The 2,4-D pesticide production waste water pretreatment method particularly comprises the following steps of: preparing the emulsion by cutting an oil phase comprising a surfactant, an additive and a membrane solvent and aqueous solution of sodium hydroxide at a high speed; dispersing the emulsion to 2,4-D pesticide waste water to perform extraction; allowing the 2,4-dichlorophenol and the 2,4-D to enter a liquid membrane phase; breaking the emulsion electrostatically to generate 2,4-dichlorophenol sodium salt and 2,4-D sodium salt; and applying to a condensation section of the product, wherein after the pretreatment, the removing rate of phenol and the 2,4-D in the waste water is over 99 percent, COD removing rate is over 57 percent and biochemical property is achieved. By the method, the 2,4-D pesticide production waste water can be discharged stably and standardly; and remarkable environmental, economic and social benefits are achieved.

The invention discloses a synergistic treatment technology for electroplating sewage. Dewaxing wastewater, nickel-containing wastewater and chromium-containing wastewater are discharged into a mixingtank and are mixed to achieve the purpose of treating wastes with wastes in order to save the cost, and a COD treatment agent and a nickel treatment agent are added to further deeply degrade chemicalcomponents in sewage in order to further reduce pollution components. Pretreatment water, plated member cleaning water and other comprehensive sewage in the electroplating process are synergisticallytreated, the wastes are treated with wastes to save the cost, the special COD treatment agent and the special nickel treatment agent are added according to the water quality condition to perform advanced treatment in order to reduce non-standard components in the sewage, so the sewage can be stably discharged after reaching the standards, the sewage treatment process in electroplating production is simplified, the production cost is saved, and the treatment efficiency is improved.

The invention discloses a plasticizer sewage treatment process. The process is characterized in that the sewage is treated according to the following steps: (1) degreasing through hydrolysis: heating up the wastewater on the alkaline condition to boil so as to make esters have hydrolytic reactions; and adding lime so as to make benzene ring substance react with calcium to generate deposition which is removed from the sewage; (2) neutralization: adding acid into the sewage to regulate the pH value of the wastewater to neutrality; (3) anaerobic treatment: on the anaerobic condition, breaking out the hardly degradable loops and converting the organisms into methane through the action of anaerobes; (4) aerobic treatment: carrying out the blast aeration of the sewage, and degrading the organisms through the action of aerobes; and (5) precipitation: separating the outputted aerobic water from the mud through a precipitation tank, discharging the supernatant, returning most of the sludge for aerobic treatment, and discharging a small amount of the sludge. The process occupies little space, requires no dilution, has low operation cost and stable emission up to the standards, and is competent for the qualified treatment of most plasticizer sewage.