A treatment process for paint wastewater and spraying wastewater

Abstract

The present invention provides a treatment process for coating wastewater and spraying wastewater, including: homogenization: stirring and homogenizing the wastewater to be treated to ensure uniform wastewater properties; coagulation: first adjusting the pH value of the wastewater, and then adding a coagulant and a flocculant aid; pressure filtration: first performing pressure filtration to obtain sludge and pressure-filtered effluent, aerating and pre-oxidizing the pressure-filtered effluent, filtering the pre-oxidized effluent, and then collecting it in a pressure-filtered effluent tank; multi-element electrocatalytic oxidation; multi-stage biochemical treatment: pumping the effluent from the previous step into an anoxic tank, an aerobic tank, an MBR tank, and a denitrification filter in sequence for treatment, and detecting the COD concentration, ammonia nitrogen concentration, total nitrogen concentration, and total phosphorus concentration of the effluent after treatment. If the standards are met, it is discharged; if not, it is refluxed to the pressure-filtered effluent tank. The present invention combines and synergistically treats processes such as coagulation, pressure filtration, multi-element electrocatalytic oxidation, and multi-stage biochemical treatment, maximizing the guarantee that the treated wastewater can meet the discharge standards. The entire system has the best stability, the smallest footprint, and the lowest operating cost.

Description

Technical Field

[0001] The invention relates to the technical field of coating wastewater and spraying wastewater treatment, and in particular to a coating wastewater and spraying wastewater treatment process. Background Art

[0002] Paint wastewater mainly comes from the cleaning and formulation experiment process of batching tanks and reactors, and has the following characteristics: intermittent discharge, large fluctuations in water quality and quantity; large differences in wastewater generated by each production process; small wastewater volume but very complex pollutant composition; high solid content in wastewater, containing a large number of nano-scale inorganic materials, such as titanium dioxide, kaolin and various colored pigments; high content of high-molecular organic compounds that are difficult to biodegrade. Spraying wastewater is divided into many types, such as cleaning wastewater, electrophoresis wastewater, spraying wastewater and domestic wastewater, as well as regularly discharged high-concentration tank pouring liquid, of which high-concentration tank pouring liquid is mainly composed of degreasing waste liquid, phosphating waste liquid, surface adjustment waste liquid, electrophoresis waste liquid, etc. Paint wastewater and spraying wastewater are currently mainly treated by a combination of "physical-chemical-biochemical", and the effluent after treatment can basically meet the national emission standards. Among them, physical and chemical treatment includes coagulation, flotation, filtration, membrane separation, adsorption, etc. Coagulation and flotation are commonly used for pre-treatment, and adsorption, filtration and membrane separation are commonly used for deep treatment; biochemical treatment includes anaerobic and aerobic processes. In view of the characteristics of high organic content and non-aerobic degradable components in paint industry wastewater, the "anaerobic-aerobic" coupling process is often used in practical applications. However, due to the large area occupied by the structure of the latter biochemical method, high one-time investment cost and complex operation, it is difficult for small and medium-sized enterprises to accept it. At present, there are few domestic engineering application cases. There is also a combined technology process of adsorption-coagulation-advanced oxidation-coagulation to treat architectural paint wastewater. Its treatment effect is stable, the effluent water quality is good, the final effluent COD is less than 500mg / L, and the total removal rate is above 80%. However, the advanced oxidation technology adopts Fenton oxidation technology, which produces more sludge and has the defect of poor economic efficiency. Summary of the invention

[0003] In order to solve the above deficiencies in the prior art, the present invention proposes a coating wastewater and spraying wastewater treatment process.

[0004] The technical solution of the present invention is achieved in this way:

[0005] A coating wastewater and spraying wastewater treatment process includes the following treatment process:

[0006] (1) Homogenization: Stir and homogenize the wastewater to be treated to ensure uniform properties of the wastewater;

[0007] (2) Coagulation: first adjust the pH value of the wastewater, then add coagulants and coagulant aids;

[0008] (3) Filter pressing: First, a plate and frame filter is used to filter to obtain sludge and filter press effluent, and the sludge is taken away for treatment; the filter press effluent is aerated and pre-oxidized, and the pre-oxidation effluent is filtered by a bag filter and then collected in the filter press effluent pool;

[0009] (4) Multi-element electrocatalytic oxidation: The effluent from the previous step is electrocatalytically oxidized using a multi-element electrocatalytic oxidation integrated machine;

[0010] (5) Multi-stage biochemical treatment: The effluent from the previous step is pumped into anoxic tank, aerobic tank, MBR tank and denitrification filter tank for treatment in sequence. After treatment, the COD concentration, ammonia nitrogen concentration, total nitrogen concentration and total phosphorus concentration of the effluent are tested. If the concentration meets the standard, the effluent is discharged to the municipal pipe network. If the concentration does not meet the standard, the effluent is returned to the filter effluent tank of step (3).

[0011] The present invention is particularly suitable for treating wastewater with a volume of ≤100m 3 / day, pH 4-10, COD≤300000mg / L, ammonia nitrogen≤500mg / L, total nitrogen≤1000mg / L, benzene and benzene homologues≤400mg / L, SS≤100g / L of paint wastewater or spraying wastewater. The paint wastewater refers to various wastewaters generated in the paint production process, including but not limited to wastewater from water-based paint production workshops, wastewater from oily paint production workshops, and various container cleaning wastewater related to paint production; the spraying wastewater includes but is not limited to cleaning wastewater generated before surface spraying and during spraying, electrophoresis wastewater, spraying wastewater, domestic wastewater and regularly discharged high-concentration tank pouring liquid.

[0012] First, the wastewater to be treated is homogenized, and then coagulated to form large particles and alum flowers in the suspended matter in the wastewater. After that, the effluent is filtered through a filter press to obtain a filter press effluent. The filter press effluent is filtered by a bag filter after pre-aeration, and then enters a multi-electrocatalytic oxidation integrated machine for electrocatalytic oxidation, so that more than 60% of the organic pollutants in it are oxidized and decomposed or even mineralized, and the difficult-to-degrade organic matter is opened and broken, and becomes organic matter that can be degraded by microorganisms, and the B / C of the wastewater is increased. Finally, anoxic + aerobic + MBR + denitrification process multi-stage biochemical treatment is carried out, and the biochemical and biochemical stages are treated by sludge + high-efficiency bacterial agent combination to achieve the goals of COD removal rate>97%, ammonia nitrogen removal rate>97%, and total nitrogen removal rate>80%. The present invention can remove most of the pollutants by pre-placing the multi-electrocatalytic oxidation treatment, reduce the pressure of the biochemical stage, shorten the residence time of the multi-stage biochemical, and reduce the floor area of ​​the multi-stage biochemical treatment system by more than 60%; in addition, the B / C of the wastewater after oxidation is increased, which can improve the biochemical efficiency and is more conducive to biochemical treatment.

[0013] The present invention combines and uses coagulation, filtration pressure, multi-electrocatalytic oxidation and multi-stage biochemical processes for coordinated treatment, thereby maximizing the guarantee that the treated wastewater can meet discharge standards. The entire system has optimal stability, minimal land occupation and lowest operating cost.

[0014] Preferably, the homogenization, the coagulation, and the filter press all adopt a batch processing method, and the multi-electrocatalytic oxidation and the multi-stage biochemical treatment all adopt a continuous processing method;

[0015] During homogenization, the stirrer is preferably arranged at a distance of 10-20 cm from the bottom of the homogenization container. A centrifugal pump is arranged at the bottom of the homogenization container. A sampling port and an observation port are arranged in the middle of the homogenization container. After homogenization is completed, samples are taken through the sampling port and a coagulation experiment is performed. After the experiment, the specific process of the next coagulation treatment is determined, such as the type and concentration of the coagulant and coagulant aid to be added. The homogenization residence time is 12-18 hours.

[0016] During coagulation, the pH value of the wastewater is first adjusted to 7.5-8.5 by sulfuric acid or sodium hydroxide and kept for 0.5-1h, then a coagulant such as PAC is added for coagulation reaction and kept for 0.5-1h, and finally a coagulant such as PAM is added and kept for 0.5-1h. If there is emulsified oil in the water that cannot be removed by coagulation and precipitation, conventional demulsifiers and reverse demulsifiers can also be added. );

[0017] During the filtration, the effluent from the filtration is first kept in the effluent pool for 6-12 hours and then filtered using a bag filter;

[0018] During multi-electrocatalytic oxidation, the wastewater stays in the multi-electrocatalytic oxidation machine for 1-1.5 hours, and the effluent after multi-electrocatalytic oxidation stays in the oxidation effluent tank for 48-72 hours;

[0019] In multi-stage biochemical treatment, the residence time of wastewater in the anoxic tank, aerobic tank, MBR tank and denitrification filter tank are 48-72h, 72-144h, 24-72h and 24-48h respectively. Aerobic liquid bacterial agent is added to the aerobic tank, and denitrification solid bacterial agent (the type and addition concentration of denitrification solid bacterial agent are based on the existing technology, and the addition concentration is preferably 1%-3%), sodium bicarbonate, carbon source (the type and addition concentration of carbon source are based on the existing technology, such as glucose, ethanol, etc.) are added to the denitrification filter tank.

[0020] Further preferably, the liquid bacterial agent added to the aerobic pool is a high-efficiency liquid bacteria composed of Bacillus and Micrococcus, wherein the Bacillus accounts for 50%-60%, the Micrococcus accounts for 40%-50%, and the added concentration of the high-efficiency liquid bacteria is preferably 1‰-1%.

[0021] Further preferably, the volume ratio of the gas volume used in the pre-oxidation treatment to the water volume of the filter press water is (50-100):1.

[0022] Further preferably, a reflux pipe is provided between the aerobic tank and the anoxic tank, and the reflux ratio is (1-3):1.

[0023] Further preferably, when the pressure difference before and after the bag filter is greater than 0.3MPa, backwashing is performed, and the backwashing water is the effluent after the multi-stage biochemical treatment, and the backwashing effluent flows back into the homogenization treatment; when the filter bag of the bag filter is damaged or the flux after backwashing drops below 70%, the filter bag is replaced.

[0024] In each treatment step, the pH of the effluent from the filter press is 6.5-8.5, COD≤30000mg / L, ammonia nitrogen≤200mg / L, total nitrogen≤500mg / L, benzene and benzene homologues≤100mg / L, SS≤50mg / L; the effluent COD after multi-electrocatalytic oxidation is ≤12000mg / L, ammonia nitrogen≤100mg / L, total nitrogen≤300mg / L, benzene and benzene homologues≤20mg / L; the effluent COD of the aerobic pool is ≤1000mg / L, Ammonia nitrogen ≤20mg / L, total nitrogen ≤100mg / L, benzene and benzene homologues ≤2mg / L; MBR pool effluent COD ≤300mg / L, ammonia nitrogen ≤10mg / L, total nitrogen ≤75mg / L, benzene and benzene homologues ≤1.5mg / L; denitrification filter effluent pH is 6.5-8.5, COD ≤280mg / L, ammonia nitrogen ≤10mg / L, total nitrogen ≤50mg / L, benzene and benzene homologues ≤1.5mg / L, SS ≤50mg / L.

[0025] More preferably, the multi-electrocatalytic oxidation integrated machine comprises: a power supply system and a main oxidation system, the main oxidation system comprises a cylindrical trough body, the upper part of the trough body is provided with a water outlet trough, the lower part is provided with a water inlet pipe, the water outlet trough is provided with a drain outlet, the trough body is provided with an electrode system, the bottom of the trough body is provided with an aeration pipe, the aeration pipe is located below the electrode system, the electrode system comprises: a columnar electrode and a plurality of electrode plates, the plurality of electrode plates are all cylindrical and layered and arranged outside the columnar electrode, the columnar electrode, the plurality of electrode plates and the trough body are concentrically arranged, particle electrodes are filled between the columnar electrode and the innermost electrode plate and between adjacent electrode plates, a plurality of oxidation treatment units are formed between the columnar electrode and the innermost electrode plate and between adjacent electrode plates, the sewage to be treated first enters the innermost oxidation treatment unit from the water inlet pipe, then deflects in sequence between the remaining oxidation treatment units, and finally discharges from the trough body through the drain outlet.

[0026] Most preferably, the multi-electrocatalytic oxidation integrated machine also includes an electrode system fixing mechanism, which includes: a cross and a supporting plate, a supporting column is provided at the bottom of the supporting plate, the supporting plate is arranged at the bottom of the trough body through the supporting column, the cross is located at the top of the trough body, the top end of the electrode plate is fixed to the cross through the electrode plate fixing piece, and the bottom end is fixed to the supporting plate through the electrode plate fixing piece.

[0027] Specifically, the support column is arranged at the bottom of the odd-numbered electrode plates from the inside to the outside. The support column is a circular ring structure, which is fixed to the supporting plate and the bottom of the trough body. The part of the circular ring structure in contact with the supporting plate and the bottom of the trough is a sealing structure, and the rest of the supporting plate is densely covered with water-permeable mesh holes.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] 1. In view of the variable water quality of paint wastewater and spraying wastewater, a coagulation system has been added, which can flexibly select the coagulation process, type of reagent and dosage according to the specific water quality;

[0030] 2. Placing the multi-electrocatalytic oxidation system before the multi-stage biochemical system can help remove more than 50% of pollutants, reduce the pressure of the multi-stage biochemical system, shorten the residence time in the multi-stage biochemical system, and reduce the footprint of the multi-stage biochemical system, which can not only help reduce its investment cost, but also significantly improve the biochemical treatment effect;

[0031] 3. The four treatment systems of coagulation, filter press, multi-electrocatalytic oxidation and biochemical treatment are used in combination. The synergistic effect makes the whole system run stably, the water effect is good and the operating cost is low. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] 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 will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0033] Figure 1 This is a schematic diagram of the structure of the multi-element electrocatalytic oxidation integrated machine used in the present invention;

[0034] Figure 2 for Figure 1 Top view of the central body oxidation system.

[0035] In the figure:

[0036] 1. Power supply system; 2. Main oxidation system; 3. Electrode plate; 4. Tank body; 5. Water inlet pipe; 6. Water outlet tank; 7. Plate fixings; 8. Drain outlet; 9. Copper busbar conductor; 10. Power busbar; 11. Aeration pipe; 12. Particle electrode; 13. Support plate; 14. Air inlet pipe; 15. Support column; 16. Power supply; 17. Columnar electrode. DETAILED DESCRIPTION

[0037] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. 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.

[0038] The following examples all adopt Figure 1 and Figure 2The multi-electrocatalytic oxidation integrated machine shown in the figure performs multi-electrocatalytic oxidation. The multi-electrocatalytic oxidation integrated machine includes: a power supply system 1, a main oxidation system 2 and an electrode system fixing mechanism; the main oxidation system 2 includes a cylindrical tank body 4, the upper part of the tank body 4 is provided with a water outlet 6, the lower part is provided with a water inlet pipe 5, the water outlet 6 is provided with a drain port 8, the tank body 4 is provided with an electrode system, the bottom of the tank body 4 is provided with an aeration pipe 11, and the aeration pipe 11 is located below the electrode system; the electrode system includes: a columnar electrode 17 and three electrode plates 3, the three electrode plates 3 are all cylindrical and layered outside the columnar electrode 17, the columnar electrode 17, the three electrode plates 3, and the tank body 4 are concentrically arranged, the columnar electrode 17 and the innermost electrode plate 3 and the adjacent electrode plates 3 are filled with particle electrodes 12, and the columnar electrode 17 and the innermost electrode plate 3 and the adjacent electrode plates 3 form three oxidation treatment units, and the waste to be treated is discharged from the wastewater treatment plant. Water first enters the innermost oxidation treatment unit from the water inlet pipe 5, then bends in sequence between the remaining two oxidation treatment units, and finally is discharged from the tank body 5 through the drain port 8; the electrode system fixing mechanism includes: a cross and a support plate 13, a support column 15 is arranged at the bottom of the support plate 13, the support plate 13 is arranged at the bottom of the tank body 4 through the support column 15, the cross is located at the top of the tank body 4, the top of the electrode plate 3 is fixed to the cross through the plate fixing member 7, and the bottom is fixed to the support plate 13 through the plate fixing member 7; specifically, the support column 15 is arranged at the bottom of the odd-numbered electrode plates 3 from the inside to the outside, the support column 15 is a circular ring structure, the circular ring structure is fixed to the support plate 13 and the bottom of the tank body 4, the part of the circular ring structure in contact with the support plate 13 and the bottom of the tank is a sealing structure to ensure that the water flow will not short-circuit, and the rest of the support plate 13 is densely covered with a permeable net. The diameter of the tank body 4 is 1500 mm, the electrode plate 3 is a ruthenium-iridium electrode plate with a thickness of 6 mm, the spacing between the electrode plates 3 is 180 mm, the filling height of the particle electrode 12 and the height ratio of the electrode plate 3 is 0.5, and the particle electrode 12 is The columnar electrode 17 is a columnar electrode with a diameter of 20 mm.

[0039] Example 1

[0040] The wastewater from a paint factory in Tianjin is mainly treated by coagulation, plate and frame filter press, multi-electrocatalytic oxidation and biochemical combined process. The water volume is 30m 3 / day, pH is 4-9, COD≤200000mg / L, ammonia nitrogen≤200mg / L, total nitrogen≤400mg / L, benzene and benzene homologues≤150mg / L, SS≤100g / L. First, adjust the pH to 7.0±0.2 with sulfuric acid and sodium hydroxide, and use PAC and PAM for coagulation and coagulant aid. The specific amount of addition is determined according to the experiment; the pH of the effluent of the plate and frame filter press system is 6.5-8.5, COD≤20000mg / L, ammonia nitrogen≤50mg / L, total nitrogen≤150mg / L, benzene and benzene homologues≤60mg / L, SS≤10mg / L; the voltage of the multi-electrocatalytic oxidation device is 30V±2V, the residence time is 1h, the effluent COD≤8000mg / L, ammonia nitrogen≤25mg / L, total nitrogen≤80mg / L, benzene and benzene homologues≤20mg / L; the biochemical system anoxic tank, aerobic The retention time of the pool, MBR pool and denitrification filter pool are 72h, 120h, 48h and 48h respectively. The COD of the aerobic pool effluent is ≤1000mg / L, ammonia nitrogen is ≤10mg / L, total nitrogen is ≤50mg / L, benzene and benzene homologues are ≤1mg / L; the COD of the MBR pool effluent is ≤280mg / L, ammonia nitrogen is ≤2mg / L, total nitrogen is ≤48mg / L, benzene and benzene homologues are ≤0.6mg / L; the pH of the denitrification filter effluent is 6.5-8.5, COD is ≤240mg / L, ammonia nitrogen is ≤2mg / L, total nitrogen is ≤40mg / L, benzene and benzene homologues are ≤0.5mg / L, SS is ≤50mg / L. The discharge standard is met.

[0041] Example 2

[0042] The sewage from a paint factory in Langfang, Hebei Province is mainly treated by coagulation, plate and frame filter press, multi-electrocatalytic oxidation and biochemical combined process. The water volume is 24m 3 / day, pH 4-9, COD ≤ 70000mg / L, ammonia nitrogen ≤ 400mg / L, total nitrogen ≤ 850mg / L, benzene and benzene homologues ≤ 50mg / L, SS ≤ 10g / L. First, adjust the pH to 7.5 ± 0.5 with sulfuric acid and sodium hydroxide, use PAC and PAM for coagulation and coagulant, and the specific amount is determined according to the experiment; the effluent pH of the plate and frame filter press system is 6.5-8.5, COD ≤ 8000mg / L, ammonia nitrogen ≤ 200mg / L, total nitrogen ≤ 500mg / L, benzene and benzene homologues ≤ 20mg / L, SS ≤ 10mg / L; the voltage of the multi-electrocatalytic oxidation device is 30V ± 2V, the residence time is 1.5h, the effluent COD ≤ 3500mg / L, ammonia nitrogen ≤ 100mg / L, total nitrogen ≤ 300mg / L, benzene and benzene homologues ≤ 2mg / L; the biochemical system The retention time of the anoxic pool, aerobic pool, MBR pool and denitrification filter are 72h, 120h, 72h and 48h respectively. The COD of the aerobic pool effluent is ≤500mg / L, ammonia nitrogen is ≤40mg / L, total nitrogen is ≤120mg / L, benzene and benzene homologues are ≤0.5mg / L; the COD of the MBR pool effluent is ≤300mg / L, ammonia nitrogen is ≤25mg / L, total nitrogen is ≤80mg / L; the pH of the denitrification filter effluent is 6.5-8.5, COD is ≤280mg / L, ammonia nitrogen is ≤25mg / L, total nitrogen is ≤50mg / L, benzene and benzene homologues are ≤0.5mg / L, SS is ≤50mg / L. The discharge standard is met.

[0043] Example 3

[0044] The wastewater from a paint factory in Suzhou, Jiangsu Province is mainly treated by coagulation, multi-electrocatalytic oxidation and biochemical combined process. The water volume is 15m 3 / day, pH is 4-9, COD≤100000mg / L, ammonia nitrogen≤350mg / L, total nitrogen≤400mg / L, benzene and benzene homologues≤120mg / L, SS≤10g / L. First, adjust the pH to 7.2±0.3 with sulfuric acid and sodium hydroxide, and use PAC and PAM for coagulation and coagulant aid. The specific amount of addition is determined according to the experiment; the effluent pH of the plate and frame filter press system is 6.5-8.5, COD≤15000mg / L, ammonia nitrogen≤200mg / L, total nitrogen≤250mg / L, benzene and benzene homologues≤60mg / L, SS≤10mg / L; the voltage of the multi-electrocatalytic oxidation device is 30V±2V, the residence time is 1h, the effluent COD≤7500mg / L, ammonia nitrogen≤100mg / L, total nitrogen≤120mg / L, benzene and benzene homologues≤20mg / L; the biochemical system anoxic tank, good The residence time of the aerobic pool, MBR pool and denitrification filter pool are 72h, 144h, 72h and 24h respectively. The COD of the aerobic pool effluent is ≤800mg / L, ammonia nitrogen is ≤40mg / L, total nitrogen is ≤50mg / L, benzene and benzene homologues are ≤4mg / L; the COD of the MBR pool effluent is ≤300mg / L, ammonia nitrogen is ≤25mg / L, total nitrogen is ≤50mg / L, benzene and benzene homologues are ≤1.5mg / L; the pH of the denitrification filter effluent is 6.5-8.5, COD is ≤280mg / L, ammonia nitrogen is ≤25mg / L, total nitrogen is ≤40mg / L, benzene and benzene homologues are ≤1.5mg / L, SS is ≤50mg / L. The discharge standard is met.

[0045] Example 4

[0046] The sewage from a spraying plant in Shandong is mainly treated by coagulation, multi-electrocatalytic oxidation and biochemical combined process. The water volume is 15m 3 / day, pH is 4-9, COD≤20000mg / L, ammonia nitrogen≤150mg / L, total nitrogen≤200mg / L, benzene and benzene homologues≤10mg / L, SS≤500mg / L. First adjust the pH to 7.2±0.3 with sulfuric acid and sodium hydroxide, use PAC and PAM for coagulation and coagulant, and the specific amount is determined according to the experiment; the effluent pH of the plate and frame filter press system is 6.5-8.5, COD≤5000mg / L, ammonia nitrogen≤70mg / L, total nitrogen≤100mg / L, benzene and benzene homologues≤5mg / L, SS≤10mg / L; the voltage of the multi-electrocatalytic oxidation device is 30V±2V, the residence time is 1h, the effluent COD≤2000mg / L, ammonia nitrogen≤35mg / L, total nitrogen≤60mg / L, benzene and benzene homologues≤1m g / L; the residence time of the anoxic pool, aerobic pool, MBR pool and denitrification filter of the biochemical system are: 48h, 72h, 24h and 24h respectively; the COD of the effluent of the aerobic pool is ≤500mg / L, ammonia nitrogen is ≤10mg / L, and the total nitrogen is ≤25mg / L; the COD of the effluent of the MBR pool is ≤300mg / L, ammonia nitrogen is ≤5mg / L, and the total nitrogen is ≤20mg / L; the pH of the effluent of the denitrification filter is 6.5-8.5, COD is ≤280mg / L, ammonia nitrogen is ≤5mg / L, total nitrogen is ≤15mg / L, benzene and benzene homologues are ≤0.1mg / L, SS is ≤50mg / L. It meets the emission standards.

[0047] The above description is only a preferred embodiment of the present invention. The directional words such as "left" and "right" used therein are for the convenience of describing the structure of the present invention and are not used to limit the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention. The structures or their connection relationships not described in detail above adopt the existing technology.

Claims

1. A treatment process for paint wastewater and spraying wastewater, characterized in that: it includes the following treatment processes: (1) Homogenization: The wastewater to be treated is stirred for homogenization; (2) Coagulation: First, adjust the pH value, and then add a coagulant and a flocculant aid; (3) Pressure filtration: Use a plate and frame filter press to perform pressure filtration on the product of the previous step, pull away the sludge for treatment, the pressure-filtered effluent enters the pre-aeration system for pre-oxidation, the pre-oxidized effluent is filtered by a bag filter, and then converges into the pressure-filtered effluent tank; (4) Multi-element electrocatalytic oxidation: Use a multi-element electrocatalytic oxidation integrated machine to perform electrocatalytic oxidation treatment on the effluent of the previous step; (5) Multi-stage biochemical treatment: Pump the effluent of the previous step into an anoxic tank, an aerobic tank, an MBR tank, and a denitrification filter in sequence for treatment. If the treatment meets the discharge standard, it is discharged into the municipal system; if not, it is refluxed to the pressure-filtered effluent tank in step (3); The amount of wastewater to be treated is ≤ 100 m 3 / day, pH is 4 - 10, COD ≤ 300000 mg / L, ammonia nitrogen ≤ 500 mg / L, total nitrogen ≤ 1000 mg / L, benzene and its homologues ≤ 400 mg / L, SS ≤ 100 g / L; The pH of the pressure-filtered effluent is 6.5 - 8.5, COD ≤ 30000 mg / L, ammonia nitrogen ≤ 200 mg / L, total nitrogen ≤ 500 mg / L, benzene and its homologues ≤ 100 mg / L, SS ≤ 50 mg / L; The effluent after multi-element electrocatalytic oxidation has COD ≤ 12000 mg / L, ammonia nitrogen ≤ 100 mg / L, total nitrogen ≤ 300 mg / L, benzene and its homologues ≤ 20 mg / L; The effluent of the aerobic tank has COD ≤ 1000 mg / L, ammonia nitrogen ≤ 20 mg / L, total nitrogen ≤ 100 mg / L, benzene and its homologues ≤ 2 mg / L; the effluent of the MBR tank has COD ≤ 300 mg / L, ammonia nitrogen ≤ 10 mg / L, total nitrogen ≤ 75 mg / L, benzene and its homologues ≤ 1.5 mg / L; the effluent of the denitrification filter has a pH of 6.5 - 8.5, COD ≤ 280 mg / L, ammonia nitrogen ≤ 10 mg / L, total nitrogen ≤ 50 mg / L, benzene and its homologues ≤ 1.5 mg / L, SS ≤ 50 mg / L.

2. The treatment process for paint wastewater and spraying wastewater according to claim 1, characterized in that: The homogenization, the coagulation, and the pressure filtration all adopt a batch treatment method, and the multi-element electrocatalytic oxidation and the multi-stage biochemical treatment both adopt a continuous treatment method; During homogenization, the residence time is 12 - 18 h; During coagulation, first adjust the pH value of the wastewater to 7.5 - 8.5 and keep it for 0.5 - 1 h, then add a coagulant for coagulation reaction and keep it for 0.5 - 1 h, and finally add a flocculant aid and keep it for 0.5 - 1 h; During pressure filtration, the pressure-filtered effluent first stays in the effluent tank for 6 - 12 h, and then is filtered by a bag filter; During multi-element electrocatalytic oxidation, the residence time of the wastewater in the multi-element electrocatalytic oxidation integrated machine is 1 - 1.5 h, and the effluent after multi-element catalytic oxidation stays in the oxidation effluent tank for 48 - 72 h; During multi-stage biochemical treatment, the residence times of the wastewater in the anoxic tank, the aerobic tank, the MBR tank, and the denitrification filter are respectively: 48 - 72 h, 72 - 144 h, 24 - 72 h, 24 - 48 h.

3. The treatment process for paint wastewater and spraying wastewater according to claim 2, characterized in that: An efficient liquid bacterium composed of Bacillus and Micrococcus is added to the aerobic tank.

4. The paint wastewater and spraying wastewater treatment process according to claim 3, characterized in that: The volume ratio of the gas volume used in the pre-oxidation to the water volume of the filter press effluent is (50 - 100):

1.

5. The paint wastewater and spraying wastewater treatment process according to claim 4, characterized in that: A reflux pipeline is provided between the aerobic tank and the anoxic tank, and the reflux ratio is (1 - 3):

1.

6. The paint wastewater and spraying wastewater treatment process according to claim 5, characterized in that: When the pressure difference before and after the bag filter is greater than 0.3 MPa, backwashing is carried out, and the backwashing water is the effluent after multi-stage biochemical treatment, and the backwashing effluent is refluxed to the homogenization treatment; When the filter bag of the bag filter is damaged or the flux drops below 70% after backwashing, the filter bag is replaced.

7. The paint wastewater and spraying wastewater treatment process according to any one of claims 1 - 6, characterized in that: The multi-element electrocatalytic oxidation integrated machine in step (4) includes: a power supply system (1) and a main body oxidation system (2). The main body oxidation system (2) includes a cylindrical tank body (4). An outlet water tank (6) is provided at the upper part of the tank body (4), and a water inlet pipe (5) is provided at the lower part. A drain port (8) is provided on the outlet water tank (6). An electrode system is provided in the tank body (4), and an air diffuser pipe (11) is provided at the bottom of the tank body (4), and the air diffuser pipe (11) is located below the electrode system. The electrode system includes: a columnar electrode (17) and a plurality of electrode plates (3). The plurality of electrode plates (3) are all arranged in a cylindrical layered ring outside the columnar electrode (17). The columnar electrode (17), the plurality of electrode plates (3), and the tank body (4) are concentrically arranged. Particle electrodes (12) are filled between the columnar electrode (17) and the innermost electrode plate (3) and between adjacent electrode plates (3). Multiple oxidation treatment units are formed between the columnar electrode (17) and the innermost electrode plate (3) and between adjacent electrode plates (3). The sewage to be treated first enters the innermost oxidation treatment unit from the water inlet pipe (5), and then flows through the remaining oxidation treatment units in sequence in a zigzag manner, and finally is discharged from the tank body (4) through the drain port (8).

8. The paint wastewater and spraying wastewater treatment process according to claim 7, characterized in that: The multi-element electrocatalytic oxidation integrated machine further includes an electrode system fixing mechanism, and the electrode system fixing mechanism includes: a cross and a supporting plate (13). A support column (15) is arranged at the bottom of the supporting plate (13). The supporting plate (13) is arranged at the bottom of the tank body (4) through the support column (15). The cross is located at the top of the tank body (4). The top end of the electrode plate (3) is fixed to the cross through a plate fixing member (7), and the bottom end is fixed to the supporting plate (13) through the plate fixing member (7). The support column (15) is arranged at the bottom of the odd-numbered electrode plates (3) from the inside to the outside. The support column (15) is of an annular structure. The annular structure is fixed to the supporting plate (13) and the bottom of the tank body (4). The part of the annular structure in contact with the supporting plate (13) and the bottom of the tank is a sealing structure, and the rest of the supporting plate (13) is densely covered with water-permeable mesh holes.

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