High-concentration coating wastewater zero discharge treatment device and process

Abstract

The invention discloses a treatment device and process based on zero discharge of high-concentration coating wastewater, wastewater passes through an adjusting tank and then enters a pretreatment module through a pipeline, the coating wastewater passes through a Fenton tank body, a coagulation tank body and a primary sedimentation tank of the pretreatment module in sequence through the pipeline to be treated, and the coating wastewater is continuously conveyed to a biochemical treatment module; the biochemical treatment module is used for carrying out anaerobic environment treatment through an anaerobic granular sludge bulking bed and then carrying out aerobic environment treatment through an aerobic aeration tank; and introducing the wastewater into a secondary sedimentation tank to separate the formed sludge from water, entering a biochemical tank, carrying out ultrafiltration and reverse osmosis treatment through a deep treatment module, recycling the treated wastewater to a production line, and recycling the generated condensate water and RO fresh water. The adopted wastewater treatment device is combined and optimized by various advanced technologies, so that the treatment efficiency and the water quality are improved, efficient recovery and reutilization of resources are also realized, and the system has good economic benefits and environmental benefits and is suitable for the requirements of modern coating wastewater treatment.

Description

Technical Field

[0001] The present invention belongs to the technical field of wastewater treatment, and in particular relates to a zero-discharge treatment device and process for high-concentration paint wastewater. Background Art

[0002] With the acceleration of industrialization, the discharge of paint wastewater is increasing, causing serious pollution to the environment. Traditional wastewater treatment methods are often unable to effectively remove organic pollutants, heavy metal ions and other harmful substances in water, resulting in low wastewater treatment efficiency and the treated water quality failing to meet the reuse standards. Therefore, the development of efficient and economical paint wastewater treatment technology has become an important issue in current environmental protection and resource reuse.

[0003] Existing coating wastewater treatment technologies mainly include physical, chemical and biological methods. These methods have their own advantages and disadvantages, but there are still many shortcomings in practical applications. For example, physical methods have a good effect on the removal of suspended solids, but have limited ability to remove soluble organic matter; although chemical methods can effectively degrade certain organic matter, they may cause secondary pollution; biological methods are more efficient in treating organic matter, but have poor adaptability to high-concentration, toxic and harmful substances.

[0004] As an emerging advanced oxidation technology, the Fenton reaction has attracted widespread attention due to its powerful oxidation ability. Fenton reagent (a mixed solution of hydrogen peroxide and divalent iron ions) can effectively degrade organic pollutants that are difficult to biochemically treat and convert them into non-toxic small molecules. However, the Fenton reaction has high requirements for water quality, and the treatment of sludge produced after the reaction also needs to be further optimized.

[0005] Coagulation and sedimentation are often used to remove suspended solids and colloidal substances in water during water treatment, but their effect is greatly affected by the type of coagulant, dosage and water quality changes. Therefore, how to improve the treatment efficiency of coagulation and sedimentation and reduce the amount of reagents used has become the focus of research.

[0006] Biological treatment technology has developed rapidly in recent years, especially the combination of anaerobic and aerobic biological treatment processes, which can effectively remove organic matter from water. However, when treating high-concentration wastewater, traditional biological treatment systems often have problems such as uneven material transfer in the reactor and poor precipitation, which affect the overall treatment effect.

[0007] In order to solve the above problems, a coating wastewater treatment device integrating multiple treatment technologies is urgently needed, which can effectively remove pollutants in water at different treatment stages and ensure that the treated water quality meets the reuse standards. By optimizing the design and linkage of each treatment module, improving treatment efficiency and reducing operating costs, it has important practical significance and broad application prospects. Summary of the invention

[0008] In view of the deficiencies in the prior art, the purpose of the present invention is to provide a zero-discharge treatment device and process for high-concentration paint wastewater, which solves the above-mentioned technical problems existing in the prior art.

[0009] The purpose of the present invention can be achieved through the following technical solutions:

[0010] A zero-discharge treatment device for high-concentration paint wastewater, including a pretreatment module, a biochemical treatment module, a deep treatment module, and a sludge concentration module.

[0011] After passing through the regulating tank, the paint wastewater enters the pretreatment module through a pipeline. The pretreatment module includes a Fenton tank, a coagulation tank, and a primary sedimentation tank. The paint wastewater is sequentially treated by the Fenton tank, the coagulation tank, and the primary sedimentation tank through a pipeline and then further transported to the biochemical treatment module.

[0012] The biochemical treatment module includes an anaerobic granular sludge expansion bed, an aerobic aeration tank, a secondary sedimentation tank, a biochemical tank, and a final sedimentation tank. The anaerobic granular sludge expansion bed is used for anaerobic environmental treatment, and then the aerobic aeration tank is used for aerobic environmental treatment to decompose organic matter in the wastewater; then the sludge is introduced into the secondary sedimentation tank to separate the formed sludge from water, and finally enters the biochemical tank, fillers are added into the biochemical tank, and microorganisms are attached to the surface of the filler medium to form a biofilm. After the introduced wastewater contacts the biofilm, the microorganisms in the wastewater are transformed, and then the wastewater is transported to the final sedimentation tank again for static precipitation;

[0013] The deep treatment module includes an ultrafiltration unit and a reverse osmosis unit. The ultrafiltration unit flows through the membrane surface under pressure, and the solvent and small molecular solutes smaller than the membrane pores permeate the membrane to become purified liquid, while the solutes and solute groups larger than the membrane pores are retained and discharged with the water flow to become concentrated liquid; the reverse osmosis unit is divided into concentrated water and fresh water after RO treatment, and the fresh water is reused;

[0014] The sludge concentration module is used for centralized treatment of the sludge collected by the pretreatment module and the biochemical treatment module.

[0015] Furthermore, the Fenton tank contains a Fenton reagent, and the oxidizing property of the Fenton reagent is used to oxidize the macromolecular oxides in the wastewater passing through;

[0016] The coagulation tank and the Fenton tank are arranged in series in multiple groups, and the coagulation tank contains a coagulant, which causes the fine colloidal particles in the wastewater to condense and flocculate into larger particles for precipitation;

[0017] The primary sedimentation tank is a filling structure with an open top, and a polymer flocculant is added to the primary sedimentation tank to hydrolyze and polycondense the wastewater solution to form a polymer precipitate. The lower layer of sediment formed enters the sludge concentration module through a pipeline, and the upper layer of clear liquid enters the biochemical treatment module through a pipeline.

[0018] Furthermore, a hydrolysis tank is also provided at the front end of the biochemical treatment module, and the upper clear liquid treated by the pretreatment module is transported to the hydrolysis tank through a pipeline, and then the upper clear liquid in the hydrolysis tank is extracted through the pipeline to the biochemical treatment module for further treatment.

[0019] Furthermore, the anaerobic granular sludge expanded bed is provided with a water circulation mechanism in the vertical direction, so that the sewage introduced into the bottom of the anaerobic granular sludge expanded bed can fully contact with the sludge particles contained inside, and the water is discharged from the top and then introduced into the bottom of the aerobic aeration tank;

[0020] Through the aeration holes arranged at the bottom of the aerobic aeration tank, microbial communities are filled in the aerobic aeration tank to form activated sludge, and oxygen is continuously passed through the aeration holes so that the activated sludge comes into contact with organic pollutants in the sewage passed in an aerobic environment to form biological coagulation, adsorption and oxidation of the organic pollutants, and then the clear liquid in the upper layer enters the biochemical tank through the secondary sedimentation tank.

[0021] Furthermore, a spray system is arranged in the biochemical pool, and the sewage at the bottom is continuously circulated to the upper part of the biochemical pool through the spray system to fully contact with the biofilm formed in the biochemical pool.

[0022] Furthermore, the sludge concentration module is connected to the bottom of the primary sedimentation tank where the pretreatment module is located, the secondary sedimentation tank where the biochemical treatment module is located, and the bottom of the final sedimentation tank through pipelines, and solid / semi-solid sludge at the bottom of the tank is extracted in a timed manner and recovered in a centralized manner into the sludge tank;

[0023] Through the secondary sedimentation of the sludge tank, the clear liquid at the upper layer is returned to the hydrolysis tank at the front end of the biochemical treatment module, or directly passed into the deep treatment module as the clear liquid for filtration;

[0024] The secondary precipitate at the lower layer is further compressed and filtered, the solid waste residue formed is centrally recovered, and the liquid is returned to the hydrolysis tank for secondary utilization.

[0025] Furthermore, the sludge concentration module is also interconnected with the anaerobic granular sludge expansion bed, aerobic aeration tank and hydrolysis tank where the pretreatment module is located through pipelines, and forms a system for extracting sludge deposited at the bottom.

[0026] Furthermore, after the wastewater treated by the biochemical treatment module is ultrafiltered by the ultrafiltration unit, the wastewater flows through the membrane surface, and the solvents and small molecular solutes smaller than the membrane pores permeate the membrane to become purified liquid, which is then transferred to the ultrafiltration water tank, and the stored water in the ultrafiltration water tank is again passed into the reverse osmosis unit for treatment through a pipeline; the formed concentrated water is returned to the hydrolysis tank at the front end of the biochemical treatment module for secondary utilization.

[0027] Furthermore, the reverse osmosis unit uses the pressure difference as a driving force to separate the solvent from the purified liquid; the fresh water obtained by the reverse osmosis enters the recovery tank for reuse, and the concentrated water obtained by the reverse osmosis flows back to the RO concentrated water tank;

[0028] Subsequently, the concentrated water in the RO concentrated water tank is further treated by an electrodialysis system (ED system for short), and the obtained fresh water is returned to the ultrafiltration water tank for production reuse. The obtained concentrated water enters the evaporation system with an evaporation temperature of 38-40°C. The concentrated water is evaporated by the evaporation system, and the obtained distilled water is directly reused in the recovery tank, and the obtained waste residue is centrally processed.

[0029] The process based on the zero-discharge treatment device for high-concentration coating wastewater comprises the following steps:

[0030] S1. Pretreatment: Add Fenton's reagent to the wastewater solution, then add coagulant to make the fine colloidal particles condense and flocculate into larger particles and precipitate, then add high molecular weight flocculation agent again to make the wastewater solution hydrolyze and condense to form high polymer precipitation;

[0031] S2, biochemical treatment: including anaerobic treatment and two-stage aerobic treatment, using anaerobic microorganisms to treat under anaerobic conditions in an anaerobic granular sludge expanded bed, followed by aerobic treatment in an aerobic aeration tank, and finally passing it into a biochemical tank to contact with the formed biofilm to transform the tiny organic matter in the wastewater, and then transporting it to the deep treatment module again;

[0032] S3, deep treatment: the effluent from biochemical treatment is treated by ultrafiltration membrane to reduce the COD of the effluent to less than 50mg / L. The ultrafiltration effluent is then treated by RO membrane desalination. The concentrated water obtained is treated by electrodialysis system and evaporation system. The concentrated water obtained by the electrodialysis system is evaporated and the generated fresh water is reused. The condensed water generated by evaporation obtained by the evaporation system is reused, and the waste residue is centrally treated.

[0033] Beneficial effects of the present invention:

[0034] 1. This device forms a multi-level treatment process through the linkage of pretreatment module, biochemical treatment module and deep treatment module. Each module treats different types of pollutants, effectively improving the overall treatment efficiency.

[0035] 2. In the pretreatment module of this device, the Fenton reaction and coagulation sedimentation can effectively remove high-concentration organic matter and suspended solids in the water, ensuring that the effluent water quality meets the reuse standard. Subsequently, ultrafiltration and reverse osmosis technology are used to further remove soluble organic matter and ions in the water, ensuring that the COD of the effluent is less than 50 mg / L, meeting high standards of water quality.

[0036] 3. This device adopts the design of sludge concentration module, which realizes the centralized treatment and recycling of sludge, reduces secondary pollution and reduces treatment costs. The supernatant can be returned to the hydrolysis tank to form a virtuous cycle. The deeply treated water can be directly reused in industrial production or other purposes, which promotes the efficient use of water resources and meets the requirements of sustainable development.

[0037] 4. This device uses an electrodialysis system, which can reduce the scale of subsequent evaporation treatment while treating concentrated water, further reducing investment and operating costs. At the same time, it treats concentrated water through low-temperature evaporation, reduces energy consumption, reduces the risk of equipment blockage, and reduces overall operating costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art are briefly introduced below.

[0039] Figure 1 Schematic diagram of the overall process flow of an embodiment of the present invention;

[0040] Figure 2 It is a simplified process flow diagram of an embodiment of the present invention;

[0041] Figure 3 It is a schematic diagram of the connection state structure of the pretreatment module and the biochemical treatment module of an embodiment of the present invention;

[0042] Figure 4 It is a schematic diagram of the partial structure of the sludge thickening module according to an embodiment of the present invention. DETAILED DESCRIPTION

[0043] The following will be combined with the accompanying drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0044] like Figure 1 , Figure 2 As shown, the embodiment of the present invention provides a device for zero-discharge treatment of high-concentration paint wastewater, including a pretreatment module, a biochemical treatment module, a deep treatment module, and a sludge concentration module.

[0045] After the paint wastewater passes through the regulating tank 101, it enters the pretreatment module through the pipeline. At this time, the regulating tank 101 can balance the fluctuation of the wastewater flow rate, ensure the stability of the water flow rate of the subsequent treatment unit, and avoid affecting the treatment effect due to excessive or too small flow rate. In addition, the regulating tank 101 can perform preliminary water quality mixing and homogenization on the incoming wastewater to reduce the impact of water quality changes on subsequent treatment processes. At the same time, in the regulating tank 101, larger particles can be precipitated during the static process, which helps to reduce the burden of subsequent treatment, and the regulating tank 101 can be used as a temporary storage facility, allowing the wastewater to stay for a short time before treatment for necessary monitoring and adjustment.

[0046] like Figure 3 As shown, the pretreatment module includes a Fenton tank 11, a coagulation tank 12, and a primary sedimentation tank 13. The paint wastewater is sequentially treated by the Fenton tank 11, the coagulation tank 12, and the primary sedimentation tank 13 through pipelines, and then further transported to the biochemical treatment module.

[0047] The Fenton tank 11 contains Fenton reagent (a mixed solution of hydrogen peroxide H2O2 and divalent iron ions), which can oxidize organic compounds into inorganic states, and its oxidation effect is very significant. 2 O 2 With 1 mol of Fe 2+ After the reaction, 1 mol of Fe is generated. 3+ , and 1 mol of OH is generated - Add 1 mol of hydroxyl radicals. It is the presence of hydroxyl radicals that makes Fenton's reagent have strong oxidizing ability. In a solution with pH = 4, the oxidation potential of OH radicals is as high as 2.73V. In nature, its oxidizing ability is second only to fluorine gas in solution. Therefore, toxic or difficult-to-biodegrade macromolecular organic matter has its carbon chain or benzene ring broken in front of Fenton's reagent, turning into non-toxic small molecules. At the same time, part of the COD of the wastewater is oxidized into CO2 and water, achieving the purpose of improving the biochemical performance of the wastewater.

[0048] The coagulation tank 12 and the Fenton tank 11 are set in series in multiple groups, and the coagulation tank 12 is filled with coagulants (the agents can be added according to the actual use situation, and the operation of the entire equipment will not be affected during the addition of the agents). The coagulants (mainly including aluminum salts, iron salts, etc.) reduce the surface charge of suspended particles in the water through electrical neutralization, reduce the mutual repulsion between particles, and thus promote the aggregation of particles, so as to destroy the stability of the sol, and make the fine colloidal particles condense and flocculate into larger particles. These floccules can be more easily separated from the water due to their greater sedimentation properties. The molecular structure of these coagulants can adsorb pollutants such as organic matter and heavy metal ions in the water, further enhance the formation of flocs and promote the sedimentation process.

[0049] The primary sedimentation tank 13 is a filling structure with an open top, and a high molecular weight flocculant is added to the primary sedimentation tank 13. At this time, the flocculant (such as a polymer, a cationic polymer, etc.) causes the suspended particles in the water to aggregate into larger flocs through physical and chemical effects. Its molecular chain can bind to the surface of the particles to form a bridging structure, thereby enhancing the interaction between the particles. The larger flocs formed by the flocculant increase the sedimentation rate of the particles, making them easier to separate from the water. This helps to reduce the burden of subsequent processing steps.

[0050] The lower sediment formed in the primary sedimentation tank 13 enters the sludge concentration module through a pipeline, and the supernatant formed enters the biochemical treatment module through a pipeline. A hydrolysis tank 201 is also set before entering the biochemical treatment module, and the supernatant treated by the pretreatment module is transported to the hydrolysis tank 201 through a pipeline, and then the supernatant in the hydrolysis tank 201 is extracted through a pipeline to the biochemical treatment module for further treatment. A stirring device (which can stir the wastewater contained in the hydrolysis tank 201) is provided at the bottom of the hydrolysis tank 201, and the hydrolysis tank 201 provides a suitable environment for the wastewater to promote the hydrolysis and degradation of organic matter. Through the hydrolysis reaction, complex organic matter is decomposed into simpler compounds (such as amino acids, fatty acids, etc.), providing available substrates for subsequent biological treatment. And the hydrolysis tank 201 can effectively remove soluble organic matter in water, reduce the organic load of wastewater, and help improve the efficiency of subsequent treatment steps (anaerobic digestion or aerobic biological treatment).

[0051] The biochemical treatment module includes an anaerobic granular sludge expansion bed 21, an aerobic aeration tank 22, a secondary sedimentation tank 23, a biochemical tank 24, and a final sedimentation tank 25. The anaerobic granular sludge expansion bed 21 is used to perform anaerobic environmental treatment, and a wastewater treatment method that uses anaerobic microorganisms to decompose organic matter under anaerobic conditions. The basic principle is that in the absence of molecular oxygen, anaerobic microorganisms convert complex organic matter in water into methane and carbon dioxide through anaerobic respiration and release energy. In the present application, the improvement of the anaerobic bioreactor is adopted, that is, the anaerobic granular sludge expansion bed 21 is adopted, the effluent recycling system is added, the liquid rising velocity in the reactor is increased, and the effluent is mixed with the influent to enter the anaerobic reactor to improve the impact resistance of the anaerobic tower (so that the sewage introduced into the bottom of the anaerobic granular sludge expansion bed 21 is fully in contact with the sludge particles contained inside). The higher liquid rising velocity eliminates the dead zone and achieves a better mud-water mixing effect. The sludge particles are in a swollen state, which strengthens the contact between the incoming water and the sludge particles and makes the reaction more complete. This process produces biogas as a by-product, which the owner can collect and reuse.

[0052] Then, the aerobic environment treatment is carried out in the aerobic aeration tank 22. Under artificial oxygenation conditions, the sewage and various microbial communities are continuously mixed and cultured to form activated sludge. The biological coagulation, adsorption and oxidation of the activated sludge are used to decompose and remove organic pollutants in the sewage. Then the sludge and water are separated in the secondary sedimentation tank 23, and most of the sludge is returned to the aeration tank, and the excess is discharged from the biological aeration system. Working method: water flows into the tank from the top of the EGSB, and then enters the secondary sedimentation tank 23, and the formed sludge is separated from the water. After sedimentation, the upper clear liquid enters the biochemical tank 24, and the sludge at the bottom of the secondary sedimentation tank 23 is pumped back to the activated sludge tank through a reflux pump to decompose the organic matter in the wastewater.

[0053] The biochemical pool 24 is filled with fillers (as the secondary aerobic treatment of the aerobic aeration pool 22). The biochemical pool is filled with fillers, and microorganisms adhere to the surface of the filler medium to form a biofilm. After the sewage contacts the biofilm, the microorganisms in the wastewater are transformed. The dissolved organic matter is adsorbed by the microorganisms and converted into H 2 O、CO 2 The sewage is purified by removing the wastewater and microbial cell substances. Then, the wastewater is transported to the final sedimentation tank 25 for static sedimentation.

[0054] In order to improve the treatment efficiency of the biochemical pool 24, a spray system is set in the biochemical pool 24. The sewage at the bottom is continuously circulated to the upper part of the biochemical pool 24 through the spray system. The spray system can effectively mix the sewage so that the microorganisms and organic matter in the sewage are evenly distributed. This uniform mixing helps to improve the activity and treatment efficiency of the microorganisms. Through spraying, the organic matter in the sewage can contact the microorganisms more quickly, promote the biodegradation reaction, and thus improve the overall treatment efficiency. The spray system can help regulate the temperature of the biochemical pool, especially in the high temperature in summer, by spraying water to cool down and maintain the best growth conditions for microorganisms. It can also be used to regularly clean the equipment and surfaces in the biochemical pool to prevent the accumulation of dirt and sediments and maintain the normal operation of the treatment system.

[0055] The sludge concentration module is used to centrally process the sludge collected by the pretreatment module and the biochemical treatment module. That is, at this time, the sludge concentration module is connected to the bottom of the primary sedimentation tank 13 where the pretreatment module is located, the secondary sedimentation tank 23 where the biochemical treatment module is located, and the bottom of the final sedimentation tank 25, respectively, through pipelines, and the solid / semi-solid sludge at the bottom of the tank is extracted in a timed and quantitative manner (with a high degree of automation), and is centrally recovered into the sludge tank 41. Through the secondary sedimentation of the sludge tank 41, the clear liquid at the upper layer is returned to the hydrolysis tank 201 at the front end of the biochemical treatment module, or directly passed into the deep treatment module as a clear liquid for filtration;

[0056] The secondary precipitate at the lower layer is further processed by the compression filter mechanism 42, the solid waste residue formed is collected and recovered, and the liquid is returned to the hydrolysis tank 201 for secondary utilization.

[0057] The sludge concentration module is also interconnected with the anaerobic granular sludge expansion bed 21, aerobic aeration tank 22 and hydrolysis tank 201 where the pretreatment module is located through pipelines, and forms an extraction of sludge deposited at the bottom, which greatly improves the continuous operation of the entire equipment without stopping.

[0058] like Figure 4 As shown, the deep treatment module includes an ultrafiltration unit 31 and a reverse osmosis unit 32. The effluent is then subjected to "UF+RO" deep treatment. After being treated with an ultrafiltration membrane, the COD of the treated effluent can be guaranteed to be less than 50 mg / L. The ultrafiltration effluent is then subjected to RO membrane desalination treatment to ensure that the total dissolved solids (TDS) in the recycled water meets the recycled water quality standard.

[0059] In the ultrafiltration process, the wastewater aqueous solution flows through the membrane surface under pressure, and the solvent (water) and small molecular solutes smaller than the membrane pores permeate the membrane to become a purified liquid (filtrate), and the solutes and solute groups larger than the membrane pores are retained and discharged with the water flow to become a concentrated liquid. The ultrafiltration process is a dynamic filtration, and the separation is completed in a flowing state. The solute is only deposited on the membrane surface to a limited extent, and the ultrafiltration rate decays to a certain extent and tends to equilibrium, and can be restored by cleaning. That is, under a certain pressure, small molecular solutes and solvents pass through an ultrafiltration membrane with a certain pore size, while large molecular solutes cannot pass through and remain on one side of the membrane, so that the large molecular substances are partially purified. That is, the ultrafiltration unit 31 flows through the membrane surface under pressure, and the solvent and small molecular solutes smaller than the membrane pores permeate the membrane to become a purified liquid, and the solutes and solute groups larger than the membrane pores are retained and discharged with the water flow to become a concentrated liquid. At this time, the purified liquid is transferred to the ultrafiltration water tank 311 for production reuse (saving the total water consumption), and the stored water in the ultrafiltration water tank 311 is again passed through the pipeline to the reverse osmosis unit 32 for treatment; the formed concentrated water is returned to the hydrolysis tank 201 at the front end of the biochemical treatment module for secondary utilization.

[0060] The reverse osmosis unit 32 is divided into concentrated water and fresh water after RO treatment, and the fresh water is reused; it is a membrane separation operation to separate the solvent from the solution. Pressure is applied to the feed liquid on one side of the membrane. When the pressure exceeds its osmotic pressure, the solvent will reversely osmosis in the direction of natural osmosis. As a result, the permeated solvent, i.e., fresh water, is obtained on the low-pressure side of the membrane; and the concentrated solution, i.e., concentrated water, is obtained on the high-pressure side. If seawater is treated by reverse osmosis, fresh water is obtained on the low-pressure side of the membrane and brine is obtained on the high-pressure side. Because it is in the opposite direction of natural osmosis, it is called reverse osmosis. According to the different osmotic pressures of various materials, a reverse osmosis pressure greater than the osmotic pressure can be used, i.e., reverse osmosis, to achieve the purpose of separation, extraction, purification and concentration. The pore size of the RO membrane used in the reverse osmosis unit 32 is much smaller than that of the UF membrane used in the ultrafiltration unit 31.

[0061] Finally, the fresh water obtained by reverse osmosis enters the recovery tank 321 for reuse, and the concentrated water obtained by reverse osmosis is returned to the RO concentrated water tank 322; the concentrated water in the RO concentrated water tank 322 is further treated by the electrodialysis system 301, which is developed on the basis of ED (electrodialysis). Electrodialysis is to use anion and cation exchange membranes alternately arranged between positive and negative electrodes, and separate the two membranes by a partition with specific properties to form two systems of concentrated water and fresh water. When salt water containing anions and cations is introduced into the compartment, under the action of the DC electric field, the cations in the fresh water compartment migrate to the cathode, the anions migrate to the anode, and the anions and cations migrate to the adjacent compartment. In this way, the ion concentration in the fresh water compartment gradually decreases, and the ion concentration in the concentrated water compartment gradually increases, and desalinated water and concentrated liquid can flow out continuously from the electrodialyzer. Electrodialysis is used for concentrated desalination before the evaporator, which can greatly reduce the scale of evaporation, reduce investment costs and evaporation treatment costs. The obtained fresh water flows back to the ultrafiltration water tank 311 , and the obtained concentrated water enters the evaporation system 302 .

[0062] The evaporation system 302 uses vacuum negative pressure to reduce the boiling point of the liquid, and the evaporation temperature is 38-40°C. The concentrated water obtained by the evaporation system 302 will be evaporated. Some organic matter will solidify under high temperature conditions and block pipes and heat exchangers. The low-temperature evaporator is specially used for evaporating and concentrating reduced aqueous solutions and treating concentrated waste liquids that are easy to stick to the wall and have sediments. The low-temperature evaporation system 302 has a low temperature during evaporation, and organic matter is not easy to solidify and block equipment and pipes. At the same time, the energy consumption is low, no cooling circulation equipment is required, and the price is low. The cost of use is low. The obtained distilled water is directly reused in the recovery box 321, and the obtained waste residues are centrally processed.

[0063] like Figure 1 As shown, a process based on a zero-discharge treatment device for high-concentration coating wastewater comprises the following steps:

[0064] S1. Pretreatment: Add Fenton reagent to the wastewater solution, and then add coagulant to make the fine colloidal particles condense and flocculate into larger particles and precipitate. Then add high-molecular-weight flocculation agent again to hydrolyze and polycondense the wastewater solution to form high polymer precipitation, thereby forming a precipitation for most of the organic matter in the wastewater, which is convenient for further filtration and treatment of the upper clear liquid. After the wastewater is first pretreated by Fenton + mixing / flocculation precipitation, the BOD / COD ratio of the wastewater can be improved, the biodegradability can be enhanced, and most of the TP and SS can be removed, which is convenient for subsequent biochemical treatment.

[0065] S2, biochemical treatment: including anaerobic treatment and two-stage aerobic treatment, using anaerobic microorganisms to treat under anaerobic conditions in the anaerobic granular sludge expanded bed 21, and then aerobically treated again in the aerobic aeration tank 22, and finally passed into the biochemical tank 24 to contact with the formed biofilm to form a transformation of the tiny organic matter in the wastewater, and then transported to the deep treatment module again. Through the biochemical treatment process, the concentration of organic pollutants in the wastewater is greatly reduced. Anaerobic biological treatment adopts the EGSB process, and the two-stage aerobic biological treatment adopts the completely mixed activated sludge method + contact oxidation method.

[0066] For the concentrated water produced during the pretreatment and biochemical treatment process, the sludge is further concentrated, the waste residue formed is recovered, and the squeezed return water flows back into the pretreatment and biochemical treatment for processing.

[0067] S3. Deep treatment: The effluent is subjected to "UF+RO" deep treatment. After being treated with ultrafiltration membrane, the COD of the treated effluent can be guaranteed to be less than 50mg / L. The ultrafiltration effluent is then desalinated with RO membrane to ensure that the total dissolved solids (TDS) in the recycled water meets the recycled water quality standards.

[0068] After the wastewater is deeply treated by RO membrane, the wastewater reuse rate can reach about 60%. About 40% of the RO concentrated water has a high salt content. This part of the RO concentrated water needs to be desalinated by the electrodialysis system first, and the desalinated fresh water is combined with the previous RO fresh water and reused in the production line.

[0069] Electrodialysis desalination produces about 20% concentrated water, which is then treated by low-temperature evaporation. The distillate (condensed water) is directly reused, and the concentrated liquid is treated as hazardous waste and entrusted to a qualified unit for centralized treatment.

[0070] Refer to the following example:

[0071] The COD and BOD classification removal rates are shown in Table 1 below (COD in paint wastewater Cr 、BOD 5 The content is extremely high, but after being treated by the method of this application, it has been greatly improved)

[0072] Table 1

[0073]

[0074]

[0075] Regarding the graded desalination rate, as shown in Table 2 below,

[0076] Table 2

[0077]

[0078] In summary, the paint wastewater treatment device not only improves the treatment efficiency and water quality through the combination and optimization of multiple advanced technologies, but also realizes the efficient recovery and reuse of resources. It has good economic and environmental benefits and is suitable for the needs of modern paint wastewater treatment.

[0079] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, and these changes and improvements all fall within the scope of the present invention to be protected.

Claims

1. A zero-discharge treatment device for high-concentration paint wastewater, comprising a pretreatment module, a biochemical treatment module, a deep treatment module, and a sludge concentration module, characterized in that: After passing through the regulating tank (101), the paint wastewater enters the pretreatment module through a pipeline. The pretreatment module includes a Fenton tank (11), a coagulation tank (12), and a primary sedimentation tank (13). After the paint wastewater passes through the Fenton tank (11), the coagulation tank (12), and the primary sedimentation tank (13) in sequence through the pipeline, it is further transported to the biochemical treatment module. The biochemical treatment module comprises an anaerobic granular sludge expansion bed (21), an aerobic aeration tank (22), a secondary sedimentation tank (23), a biochemical tank (24), and a final sedimentation tank (25). The anaerobic environment treatment is carried out through the anaerobic granular sludge expansion bed (21), and then the aerobic environment treatment is carried out through the aerobic aeration tank (22) to decompose organic matter in the wastewater; then the wastewater is introduced into the secondary sedimentation tank (23), the formed sludge is separated from the water, and finally the wastewater is introduced into the biochemical tank (24), fillers are added in the biochemical tank (24), and microorganisms are attached to the surface of the filler medium to form a biofilm. After the introduced wastewater contacts the biofilm, the microorganisms in the wastewater are transformed, and then the wastewater is transported to the final sedimentation tank (25) again for static sedimentation; The deep treatment module comprises an ultrafiltration unit (31) and a reverse osmosis unit (32). The ultrafiltration unit (31) flows through the membrane surface under pressure, and the solvent and small molecular solutes smaller than the membrane pores permeate the membrane to become purified liquid, while the solutes and solute groups larger than the membrane pores are retained and discharged with the water flow to become concentrated liquid; the reverse osmosis unit (32) is separated into concentrated water and fresh water after RO treatment, and the fresh water is reused; The sludge concentration module is used for centralized treatment of the sludge collected by the pretreatment module and the biochemical treatment module.

2. The zero-discharge treatment device for high-concentration paint wastewater according to claim 1 is characterized in that: The Fenton tank (11) contains a Fenton reagent, which oxidizes the macromolecular oxides in the wastewater passing through it through the oxidizing property of the Fenton reagent; The coagulation tank (12) and the Fenton tank (11) are arranged in series in multiple groups, and the coagulation tank (12) contains a coagulant, which causes the fine colloidal particles in the wastewater to condense and flocculate into larger particles for precipitation; The primary sedimentation tank (13) is a filling structure with an open top, and a high molecular flocculant is added to the primary sedimentation tank (13) to cause the wastewater solution to undergo hydrolysis and polycondensation to form a high polymer precipitate. The lower layer of precipitate formed enters the sludge concentration module through a pipeline, and the upper layer of clear liquid formed enters the biochemical treatment module through a pipeline.

3. The zero-discharge treatment device for high-concentration paint wastewater according to claim 1 is characterized in that: A hydrolysis tank (201) is also provided at the front end of the biochemical treatment module, and the upper clear liquid treated by the pretreatment module is transported to the hydrolysis tank (201) through a pipeline, and then the upper clear liquid in the hydrolysis tank (201) is extracted through the pipeline to the biochemical treatment module for further treatment.

4. The zero-discharge treatment device for high-concentration paint wastewater according to claim 1 is characterized in that: The anaerobic granular sludge expanded bed (21) is provided with a water circulation mechanism in the vertical direction, so that the sewage introduced into the bottom of the anaerobic granular sludge expanded bed (21) can fully contact with the sludge particles contained inside, and the water is discharged from the top and then introduced into the bottom of the aerobic aeration tank (22); Through the aeration holes provided at the bottom of the aerobic aeration tank (22), a microbial community is filled in the aerobic aeration tank (22) to form activated sludge, and oxygen is continuously passed through the aeration holes so that the activated sludge contacts with organic pollutants in the sewage passed in an aerobic environment, thereby forming biological coagulation, adsorption and oxidation of the organic pollutants, and then the clear liquid in the upper layer enters the biochemical tank (24) through the secondary sedimentation tank (23).

5. The zero-discharge treatment device for high-concentration paint wastewater according to claim 1 is characterized in that: A spray system is arranged in the biochemical pool (24), and the sewage at the bottom is continuously circulated to the upper part of the biochemical pool (24) through the spray system, so as to fully contact with the biofilm formed in the biochemical pool (24).

6. The zero-discharge treatment device for high-concentration paint wastewater according to claim 3 is characterized in that: The sludge concentration module is connected to the bottom of the primary sedimentation tank (13) where the pretreatment module is located, the secondary sedimentation tank (23) where the biochemical treatment module is located, and the bottom of the final sedimentation tank (25) through pipelines, and solid / semi-solid sludge at the bottom of the tank is extracted in a timed manner and collected and recovered in a sludge tank (41); Through secondary sedimentation in the sludge pool (41), the clear liquid at the upper layer is returned to the hydrolysis pool (201) at the front end of the biochemical treatment module, or is directly passed into the deep treatment module as the clear liquid for filtration; The secondary precipitate at the lower layer is further compressed and filtered, and the solid waste residue formed is collected and recovered, and the liquid is returned to the hydrolysis tank (201) for secondary utilization.

7. The zero-discharge treatment device for high-concentration paint wastewater according to claim 6 is characterized in that: The sludge concentration module is also interconnected with the anaerobic granular sludge expansion bed (21), the aerobic aeration tank (22) and the hydrolysis tank (201) where the pretreatment module is located through pipelines, and is used to extract the sludge deposited at the bottom.

8. The zero-discharge treatment device for high-concentration paint wastewater according to claim 6 is characterized in that: After the wastewater treated by the biochemical treatment module is ultrafiltered by the ultrafiltration unit (31), the wastewater flows through the membrane surface, and the solvent and small molecular solutes smaller than the membrane pores permeate the membrane to become purified liquid. The purified liquid is then transferred to the ultrafiltration water tank (311), and the stored water in the ultrafiltration water tank (311) is again passed through a pipeline to the reverse osmosis unit (32) for treatment; the concentrated water formed is returned to the hydrolysis tank (201) at the front end of the biochemical treatment module for secondary utilization.

9. The zero-discharge treatment device for high-concentration paint wastewater according to claim 8 is characterized in that: The reverse osmosis unit (32) uses the pressure difference as a driving force to separate the solvent from the purified liquid; the fresh water obtained by the reverse osmosis enters the recovery tank (321) for reuse, and the concentrated water obtained by the reverse osmosis flows back to the RO concentrated water tank (322); Subsequently, the concentrated water in the RO concentrated water tank (322) is further processed by the electrodialysis system (301), and the obtained fresh water is returned to the ultrafiltration water tank (311) for production reuse. The obtained concentrated water enters the evaporation system (302) at an evaporation temperature of 38 to 40° C. The obtained concentrated water is evaporated by the evaporation system (302), and the obtained distilled water is directly reused in the recovery tank (321), and the obtained waste residue is centrally processed.

10. The process based on the zero-discharge treatment device for high-concentration coating wastewater according to any one of claims 1 to 9, characterized in that: The following steps are involved: S1. Pretreatment: Add Fenton's reagent to the wastewater solution, then add coagulant to make the fine colloidal particles condense and flocculate into larger particles and precipitate, then add high molecular weight flocculation agent again to make the wastewater solution hydrolyze and condense to form high polymer precipitation; S2, biochemical treatment: including anaerobic treatment and two-stage aerobic treatment, using anaerobic microorganisms to treat under anaerobic conditions in an anaerobic granular sludge expansion bed (21), then aerobically treated again in an aerobic aeration tank (22), and finally passed into a biochemical tank (24) to contact with the formed biofilm to transform the microorganisms in the wastewater, and then transported to the deep treatment module again; S3, deep treatment: the effluent from the biochemical treatment is treated by an ultrafiltration membrane to reduce the COD of the effluent to less than 50 mg / L. The ultrafiltration effluent is then treated by an RO membrane for desalination. The concentrated water obtained is treated by an electrodialysis system (301) and an evaporation system (302). The concentrated water obtained by the electrodialysis system (301) is evaporated and the fresh water generated is reused. The condensed water generated by the evaporation obtained by the evaporation system (302) is reused. Waste residues are centrally treated.

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