Biochemical-ozone oxidation-biochemical coupling treatment method for high-salt toxic wastewater

Abstract

The invention discloses a biochemical-ozone oxidation-biochemical coupling treatment method for high-salt toxic wastewater, which comprises the following steps: sequentially carrying out biochemical COD (Chemical Oxygen Demand) degradation and denitrification on the wastewater in a first-stage anoxic tank, and introducing effluent into a first-stage sedimentation tank for sedimentation; degradation-resistant substance modification and toxicity reduction are carried out in the first-stage ozone oxidation pond; cOD (Chemical Oxygen Demand) degradation and ammonia nitrogen nitration are carried out in the first-stage aerobic tank, effluent of the first-stage aerobic tank internally flows back to the first-stage anoxic tank, and the internal reflux ratio is 100-300%; carrying out denitrification in a second-stage anoxic tank; settling in a secondary settling pond; ozone oxidation is carried out in a secondary ozone oxidation pond; and finally, COD degradation and ammonia nitrogen nitration are carried out in the second-stage aerobic tank, effluent of the second-stage aerobic tank flows back to the first-stage anoxic tank, and the external reflux ratio is 100-300%. The process provided by the invention adopts a multi-stage coupling design of multi-stage reflux and ozone oxidation and biochemical treatment, solves the problems of low biochemical treatment efficiency and weak impact resistance in a high-salt and high-toxicity environment, optimizes the ozone utilization rate, and realizes efficient, stable and low-cost treatment of high-salt toxic wastewater.

Description

Technical Field

[0001] The invention belongs to the technical field of industrial wastewater treatment, and specifically relates to a biochemical-ozone oxidation-biochemical coupling treatment method for high-salt toxic nitrogen-containing wastewater in an industrial park. Background Art

[0002] High-salinity toxic wastewater is a common type of difficult-to-treat wastewater in industrial production. The high-salinity toxic wastewater referred to in the present invention refers to wastewater with high salinity, high organic matter content and high toxicity, and specifically meets the following characteristics:

[0003] (1) Salinity: TDS>10000mg / L or conductivity>15000μS / cm.

[0004] (2) Organic matter content: COD>500mg / L.

[0005] (3) Toxicity: According to the U.S. EPA's "Toxicity Unit (TU)" value classification standard, wastewater grade IV, 10≤TU<100, highly toxic.

[0006] (4) Biochemical properties: B / C<0.3.

[0007] This type of wastewater mainly comes from the following industries:

[0008] (1) Petrochemical industry: wastewater generated by oil refining, ethylene production, polyester production, etc.

[0009] (2) Pharmaceutical industry: wastewater generated during the production of antibiotics, vitamins and other drugs.

[0010] (3) Dye and pigment industry: wastewater generated during dye synthesis and pigment production.

[0011] (4) Pesticide industry: wastewater generated during the production of various pesticides.

[0012] (5) Coal chemical industry: wastewater generated during coal gasification, coal liquefaction, etc.

[0013] (6) Leather processing industry: salt- and chromium-containing wastewater generated during the leather making process.

[0014] (7) Electroplating industry: wastewater containing heavy metals and cyanide generated during the electroplating process.

[0015] (8) Coking industry: phenol-cyanide wastewater generated during coal distillation.

[0016] At present, the main methods for treating high-salt toxic wastewater include:

[0017] (1) Physical and chemical methods: such as coagulation and sedimentation, adsorption, membrane separation, etc. Although these methods can remove some pollutants, it is difficult to effectively degrade difficult-to-biodegrade organic matter and the operating costs are relatively high.

[0018] (2) Biological treatment methods: such as activated sludge method, biofilm method, etc. These methods are effective in removing biodegradable organic matter, but high salinity and toxic substances will inhibit microbial activity, resulting in unstable treatment effects.

[0019] (3) Advanced oxidation methods: such as Fenton oxidation, ozone oxidation, etc. These methods have good oxidation effects on refractory organic matter, but they are costly when used alone and may produce toxic intermediates.

[0020] (4) Evaporation crystallization method: It can achieve zero wastewater discharge, but it has high energy consumption and cannot effectively remove organic pollutants.

[0021] It can be seen that the existing treatment technology for high-salt toxic wastewater has the following problems:

[0022] (1) It is difficult for a single treatment process to simultaneously meet the requirements of reducing COD and toxicity of high-salinity toxic wastewater.

[0023] (2) During the biological treatment process, high salinity and toxic substances inhibit the activity of microorganisms, resulting in unstable treatment effects.

[0024] (3) Advanced oxidation processes are costly when used alone and may produce toxic intermediates.

[0025] (4) Traditional processes cannot achieve economical and efficient treatment of high-salinity toxic wastewater.

[0026] Therefore, it is of great significance to develop a new process that can effectively treat high-salt toxic wastewater while taking into account both treatment effect and economy. Summary of the invention

[0027] The purpose of the present invention is to provide a biochemical-ozone oxidation-biochemical coupling treatment method for high-salinity toxic wastewater in view of the deficiencies in the prior art, which can achieve efficient, stable and economical treatment of high-salinity toxic wastewater.

[0028] Specifically, the method of the present invention aims to solve the following technical problems:

[0029] (1) Improve the stability and efficiency of high-salinity toxic wastewater treatment;

[0030] (2) Overcome the inhibition of high salinity and toxic substances on the activity of COD-degrading bacteria, nitrifying bacteria and denitrifying bacteria, and make full use of the tolerance and impact resistance of different bacteria under high salinity and high toxicity wastewater conditions;

[0031] (3) Ensure that the effluent meets the standard stably, i.e. COD≤50mg / L, NH3-N≤5mg / L, TN≤15mg / L; and achieve ultra-low discharge of each effluent index, i.e. COD≤30mg / L, NH3-N≤1mg / L, TN≤5mg / L;

[0032] (4) Optimize the layout of treatment units, shorten the overall hydraulic retention time, and reduce project investment and land occupation;

[0033] (5) Reduce processing costs and improve economic feasibility;

[0034] (6) Achieve standard discharge and reuse of high-salinity toxic wastewater.

[0035] To achieve the above object, the present invention adopts the following technical solution:

[0036] The present invention is A method for treating high-salinity toxic wastewater by biochemical-ozone oxidation-biochemical coupling, characterized in that the method comprises the following steps: passing the high-salinity toxic wastewater after degreasing and precipitation pretreatment through the following treatment units in sequence:

[0037] (1) Primary anoxic tank: for denitrification and degradation of biodegradable COD;

[0038] (2) Primary sedimentation tank: to separate mud and water and remove SS and colloids;

[0039] (3) Primary ozone oxidation pool: treats refractory COD, reduces toxicity and improves biodegradability;

[0040] (4) Primary aerobic pool: COD degradation and ammonia nitrogen nitrification;

[0041] (5) Secondary anoxic tank: for denitrification;

[0042] (6) Secondary sedimentation tank: to separate mud and water and remove SS and colloids;

[0043] (7) Secondary ozone oxidation pool: treats refractory COD and further reduces toxicity;

[0044] (8) Secondary aerobic pool: used to ensure that effluent COD and NH3-N meet standards.

[0045] On the basis of the above scheme of the present invention, by adjusting the ozone dosage, reflux ratio and other process parameters, COD≤50mg / L, NH3-N≤5mg / L, TN≤15mg / L can be achieved; according to the treatment needs, the ozone dosage, reflux ratio and other process parameters are further optimized, and ultra-low emissions of various effluent indicators can also be achieved, namely: COD≤30mg / L, NH3-N≤1mg / L, TN≤5mg / L.

[0046] 2. One of the core innovations of the present invention is the use of a multi-stage internal reflux design, which specifically includes:

[0047] (1) The effluent from the primary aerobic tank is internally refluxed to the primary anoxic tank, with the internal reflux ratio being 100% to 300%;

[0048] (2) The effluent from the secondary aerobic tank is returned to the primary anoxic tank, and the external return ratio is 100% to 300%;

[0049] (3) The effluent from the primary aerobic tank is returned to the primary ozone oxidation tank for ozone jet addition, with a return ratio of 50% to 150%;

[0050] (4) The effluent from the secondary aerobic tank is returned to the secondary ozone oxidation tank for ozone jet addition, and the return ratio is 100% to 300%.

[0051] This multi-stage reflux design can improve the system's processing efficiency, enhance the denitrification effect, and optimize the utilization of ozone.

[0052] 3. The second core innovation of the present invention is to place the primary ozone oxidation tank between the primary anoxic tank and the primary aerobic tank. This unique arrangement fully considers the differences in tolerance of different microbial communities to toxicity and salinity, as well as the impact of ozone oxidation on subsequent biological treatment; it achieves comprehensive optimization of treatment efficiency, economy and stability. Specifically:

[0053] (1) Differences in tolerance of microbial communities: Nitrifying bacteria (such as nitrite bacteria and nitrifying bacteria) have the weakest tolerance to toxicity and salinity; denitrifying bacteria have the second lowest tolerance; COD-degrading bacteria (mainly heterotrophic bacteria) have the strongest tolerance.

[0054] (2) Layout of the ozone oxidation pool: Placing the ozone oxidation pool after the primary anoxic pool can first utilize the relatively strong tolerance of COD degrading bacteria and denitrifying bacteria to remove some easily degradable organic matter and perform preliminary denitrification. The ozone oxidation process can significantly reduce the toxicity of wastewater, improve biodegradability, and create more favorable conditions for subsequent aerobic treatment and nitrification treatment. The wastewater after ozone oxidation treatment enters the primary aerobic pool, where the water quality conditions are more suitable for the growth of sensitive nitrifying bacteria, which is conducive to improving the efficiency of ammonia nitrogen removal.

[0055] (3) Impact of ozone oxidation on subsequent treatment: Ozone oxidation can break down the molecular structure of refractory organic matter, increase the BOD5 / COD ratio of wastewater, and create favorable conditions for subsequent biological treatment. Ozone oxidation effluent will be supersaturated with dissolved oxygen, which is beneficial to subsequent aerobic treatment and can reduce aeration requirements.

[0056] (4) Improved treatment efficiency: This arrangement achieves the rational protection and utilization of different microbial communities, improving the overall treatment efficiency. The introduction of ozone oxidation significantly improves the biodegradability of wastewater, allowing subsequent biological treatment units to operate more efficiently. Overall, this arrangement achieves a significant reduction in the total residence time of the anoxic and aerobic tanks, improving treatment capacity and economic benefits.

[0057] (5) Enhanced system stability: The introduction of ozone oxidation provides more stable water inlet conditions for subsequent biological treatment units, reducing the impact of high salt and high toxicity on microorganisms. By rationally arranging the sequence of treatment units, the advantages of each unit are fully utilized, and the impact resistance of the entire system is improved.

[0058] 4. To improve the biological treatment efficiency and the impact resistance of the system, the present invention adopts biofilm technology, such as contact oxidation technology, MBBR technology or MBR technology, in the primary anoxic tank, the primary aerobic tank, the secondary anoxic tank and the secondary aerobic tank.

[0059] 5. To further improve the adaptability of the system to high-salt environments, the present invention adds a salt-tolerant bacterial agent to the above-mentioned biological treatment unit. At the same time, the excess sludge discharged from the sedimentation tank enters the salt-tolerant bacterial community cultivation system for a cultivation time of no less than 24 hours.

[0060] 6. The salt-tolerant bacterial colony culture system adopts the A / O process, and the inlet water of the culture pool is the outlet water of the secondary aerobic pool with a salinity of not less than 2%. The A / O process parameters are set as follows: temperature 20-35°C, pH 7.5-8.5, dissolved oxygen in the A pool less than 0.3 mg / L, and dissolved oxygen in the O pool higher than 2 mg / L.

[0061] 7. In order to optimize the denitrification process of the anoxic tank, the present invention divides the primary anoxic tank into three compartments and sets a dissolved oxygen gradient: the dissolved oxygen in the first compartment does not exceed 0.2 mg / L, the dissolved oxygen in the second compartment does not exceed 0.8 mg / L, and the dissolved oxygen in the third compartment is 1.0-1.5 mg / L.

[0062] 8. The present invention adopts advanced oxidation technology to enhance the treatment effect of refractory organic matter. The primary ozone oxidation tank can adopt O3 contact oxidation technology or O3 / H2O2 technology; the secondary ozone oxidation tank adopts O3 / H2O2 technology; and the primary ozone and secondary ozone, according to the water quality and treatment requirements, the ozone dosage is 20-200 mg / L, and the H2O2 dosage is 30%-70% of the ozone dosage.

[0063] Compared with the prior art, the beneficial technical effects of the present invention include:

[0064] (1) Through innovative process layout, especially the unique location of the primary ozone oxidation tank, efficient and stable treatment of high-salinity toxic wastewater is achieved, overcoming the limitations of a single treatment process.

[0065] (2) The optimized sequence of treatment units fully utilizes the characteristics of each microbial community, protecting the sensitive bacterial community while giving full play to the advantages of the tolerant bacterial community, significantly improving the overall treatment efficiency.

[0066] (3) Reasonable ozone oxidation tank layout avoids the inhibition of denitrification process by high dissolved oxygen. At the same time, it creates favorable conditions for subsequent biological treatment by reducing toxicity, thereby significantly shortening the treatment time.

[0067] (4) The multi-stage internal reflux design not only improves the denitrification efficiency, but also optimizes the utilization rate of ozone and reduces operating costs.

[0068] (5) The application of biofilm technology and the addition of salt-tolerant bacteria significantly improved the adaptability and stability of the biological treatment system to high-salt environments.

[0069] (6) The design of the salt-tolerant bacterial culture system achieves efficient utilization of sludge and continuous domestication of microorganisms, further improving treatment efficiency and system stability.

[0070] (7) The dissolved oxygen gradient setting of the primary anoxic tank optimizes the denitrification process and improves the denitrification efficiency.

[0071] (8) The application of advanced oxidation technology effectively degrades difficult-to-biodegrade organic matter and improves the biodegradability of wastewater.

[0072] (9) This method has strong applicability and scalability, and can be applied to the treatment of a variety of high-salt toxic wastewaters, and has important practical application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0073] The present invention is further described below in conjunction with the accompanying drawings and embodiments:

[0074] Figure 1 This is the biochemical-ozone oxidation-biochemical coupling treatment process of high-salt toxic wastewater of the present invention. DETAILED DESCRIPTION

[0075] The specific technical solutions of the present invention are further described below with reference to the accompanying drawings, so as to facilitate further understanding of the present invention by those skilled in the art, and do not constitute a limitation on the rights thereof.

[0076] Example 1

[0077] The water quality of the influent of a chemical park industrial wastewater plant after pretreatment: TDS 43000mg / L, COD3000mg / L, ammonia nitrogen 229mg / L, TN 268mg / L ，TU value 87 (high toxicity). The above pretreated industrial wastewater was treated by the biochemical-ozone oxidation-biochemical-ozone-biochemical process of the present invention and the existing A / O+ozone oxidation process, respectively, and the common parameters of the two processes were: total ozone dosage 200 mg / L, total ozone reaction time 3 h, total residence time of the biochemical device 48 h, and nitrification liquid reflux ratio 200%.

[0078] A. Existing technology: A / O+ ozone oxidation

[0079] The high-salt toxic wastewater that has been pre-treated by oil removal and sedimentation enters the anaerobic section for nitrogen and phosphorus removal, then enters the aerobic section to remove organic matter, and finally enters the ozone oxidation tank to treat difficult-to-degrade COD and reduce toxicity.

[0080] B. Process of the present invention: biochemical-ozone oxidation-biochemical-ozone-biochemical process

[0081] like Figure 1As shown, the high-salt toxic wastewater is first subjected to oil removal and sedimentation pretreatment, and then enters the primary anoxic tank for denitrification and degradation of biodegradable COD; then enters the primary sedimentation tank for mud-water separation and removal of SS and colloids; then enters the primary ozone oxidation tank to treat the difficult-to-degrade COD, reduce toxicity and improve biodegradability, and the primary ozone oxidation tank adopts the O3 / H2O2 process; then enters the primary aerobic tank to degrade COD and achieve ammonia nitrogen nitrification; then enters the secondary anoxic tank for denitrification; then enters the secondary sedimentation tank for mud-water separation and removal of SS and colloids; then enters the secondary ozone oxidation tank to treat the difficult-to-degrade COD and further reduce toxicity, and the secondary ozone oxidation tank adopts the O3 / H2O2 process; then enters the secondary aerobic tank to degrade COD and achieve ammonia nitrogen nitrification, and the secondary aerobic tank can be used to ensure that the effluent COD and NH3-N meet the standards. Finally, the treated wastewater enters the effluent monitoring tank to monitor whether its discharge meets the standards. Among them, the effluent of the primary aerobic pool is internally refluxed to the primary anoxic pool, and the internal reflux ratio is 200%; the effluent of the secondary aerobic pool is externally refluxed to the primary anoxic pool, and the external reflux ratio is 0-300%; the effluent of the primary aerobic pool is refluxed to the primary ozone oxidation pool for ozone jet addition, and the reflux ratio is 100%; the effluent of the secondary aerobic pool is refluxed to the secondary ozone oxidation pool for ozone jet addition, and the reflux ratio is 150%. This embodiment also includes a salt-tolerant bacteria culture system (not shown in the attached drawings), the inlet water of the salt-tolerant bacteria culture system is the effluent of the secondary aerobic pool, and the inlet salinity of the culture tank of the salt-tolerant bacteria culture system is 4%; the residual sludge discharged from the primary sedimentation tank and the secondary sedimentation tank enters the salt-tolerant bacteria culture system, and the culture time of the salt-tolerant bacteria is not less than 24h. The salt-tolerant bacterial culture system adopts the A / O process. The A / O pool culture process parameters are: temperature 30°C, pH 8, dissolved oxygen in pool A lower than 0.3 mg / L, dissolved oxygen in pool O higher than 2 mg / L. The carbon sources and nutrients required for culture are sodium acetate, sucrose, corn syrup powder, yeast powder, biological promoter, and potassium chloride.

[0082] The test results are compared as follows.

[0083] Table 1 Comparison of actual influent TU values

[0084]

[0085] Table 2 Comparison of COD treatment effects

[0086]

[0087] Table 3 Comparison of ammonia nitrogen removal effects

[0088]

[0089] Table 4 Comparison of total nitrogen removal effects

[0090]

[0091]

[0092] Table 5 System stability (continuous operation 30 days data)

[0093]

[0094] Table 6 Comparison of salt tolerance (influent salinity suddenly increased by 50%)

[0095]

[0096] in conclusion:

[0097] (1) Toxicity reduction capability: External reflux dilution can reduce the biological toxicity of the influent from high toxicity (10≤TU<100) to moderate toxicity (1≤TU<10), effectively reducing the inhibition of biological toxicity on the biochemical system.

[0098] (2) Treatment effect: Compared with the A / O+ozone oxidation process, the process of the present invention shows significant advantages in the removal of COD, ammonia nitrogen and total nitrogen. As the external reflux ratio increases, the advantages of the process of the present invention become more obvious.

[0099] (3) System stability: The process of the present invention exhibits stronger shock resistance and stability, especially under conditions of higher external reflux ratios. This may be due to the fact that the multi-stage treatment and internal circulation design enhance the buffering capacity of the system.

[0100] (4) Salt tolerance: Facing salinity shock, the process of the present invention shows stronger adaptability, which may be due to the synergistic effect of the cultivation of salt-tolerant microorganisms and multi-stage ozone oxidation.

[0101] (5) Economical: Although the structure of the process of the present invention is relatively complex, due to the improvement of treatment efficiency, the overall operating cost is still slightly lower than that of the A / O + ozone oxidation process.

[0102] (6) Optimal external reflux ratio: Taking into account the treatment effect and operating cost, an external reflux ratio of 200% seems to be the best choice. Under this condition, the treatment effect is significantly improved while the cost increase is relatively small.

[0103] Example 2

[0104] A pretreated calcium chloride rare earth organic wastewater, TDS 31000mg / L, COD 320mg / L, ammonia nitrogen 50mg / L, TN 54mg / L, TU value 68 (high toxicity), pilot treatment scale 2.4m 3 / d. The process of the present invention is used for treatment, the two-stage ozone dosage is 180 mg / L, the total residence time of the two-stage ozone reaction is 3h, the total residence time of the biochemical device is 36h, the effluent of the primary aerobic pool is internally refluxed to the primary anoxic pool, and the internal reflux ratio is 200%; the effluent of the secondary aerobic pool is externally refluxed to the primary anoxic pool, and the external reflux ratio is 0-300%; the effluent of the primary aerobic pool is refluxed to the primary ozone oxidation pool for ozone jet addition, and the reflux ratio is 100%; the effluent of the secondary aerobic pool is refluxed to the secondary ozone oxidation pool for ozone jet addition, and the reflux ratio is 100%. The influent salinity of the culture pool of the salt-tolerant bacterial culture system is 3%, and the process parameters of the A / O culture pool are: temperature 30℃, pH 8, dissolved oxygen in the A pool is lower than 0.3 mg / L, and dissolved oxygen in the O pool is higher than 2 mg / L. The carbon source and nutrition required for culture are glucose, methanol, corn syrup powder, molasses, yeast powder, biological promoter, and potassium chloride. The effect of external reflow from different secondary aerobic tanks to the primary anoxic tank on sewage treatment is shown in Table 7.

[0105] Table 7 Treatment effect of different external reflux ratios of the present invention on sewage

[0106]

[0107]

[0108] As shown in Table 7, when the external reflux ratio increases, the removal effects of COD, ammonia nitrogen and TN are better. This is because the wastewater contains toxic organic substances such as rare earth flotation aids. External reflux can effectively dilute the biological toxicity of the wastewater and ensure the metabolic activity of microorganisms and the removal effect of pollutants under high-salt toxic conditions. At 200% and 300% external reflux ratios, the actual influent TU value and the removal effects of ammonia nitrogen and TN are very similar. Therefore, for this kind of calcium chloride rare earth organic wastewater after pretreatment, the external reflux ratio can be adjusted to 200% according to the treatment requirements and economy.

[0109] Example 3

[0110] A calcium chloride rare earth organic wastewater after pretreatment, TDS 31000mg / L, COD 320mg / L, ammonia nitrogen 50mg / L, TN 54mg / L, TU value 68 (high toxicity). The integrated biochemical-ozone-biochemical coupling device of the present invention, the integrated biochemical-ozone-biochemical device without external reflux, and the non-integrated biochemical-ozone-biochemical coupling device are respectively used, the sewage treatment scale is 10000t / d, and the common parameters are that the effluent of the primary aerobic pool is returned to the primary ozone oxidation pool for ozone jet addition, and the reflux ratio is 100%; the effluent of the secondary aerobic pool is returned to the secondary ozone oxidation pool for ozone jet addition, and the reflux ratio is 100%. The influent salinity of the culture pool of the salt-tolerant bacterial culture system is 3%. The process parameters of the A / O culture pool are: temperature 30°C, pH 8, dissolved oxygen in the A pool is lower than 0.3 mg / L, and dissolved oxygen in the O pool is higher than 2 mg / L. The carbon sources and nutrients required for culture are glucose, methanol, corn syrup powder, molasses, yeast powder, biological promoter, and potassium chloride. The operating parameters of different devices and the comparison of sewage treatment effects are shown in the following table.

[0111] Table 8 Comparison of sewage treatment effects of different devices

[0112]

[0113] It can be seen from Table 8 that in order to achieve similar treatment effects, the biochemical-ozone-biochemical device without external reflux needs to increase the total ozone dosage to 500 mg / L, extend the ozone residence time to 4h, and the total biochemical residence time to 84h, which is much larger than the biochemical-ozone-biochemical coupling device with external reflux in this process (180 mg / L, 3h, 36h). This is because this process adopts an external reflux design. This multi-stage reflux design can optimize the nitrogen conversion process in the reaction stage by adjusting the reflux ratio. The reflux can help stabilize the microbial community, promote the degradation of organic matter and nitrogen pollutants, accelerate the biochemical reaction rate, and reduce the required biochemical residence time; at the same time, the deep ozone oxidation treatment of low-index biochemical effluent and the synergistic effect of ozone biochemistry also optimize the utilization rate of ozone, with a small ozone dosage and a shortened reaction time. According to the analysis of the change of biological toxicity of wastewater, the inlet TU value is 68, and the actual inlet TU value of the device without external reflux is 43 under the dilution effect of the primary nitrification liquid reflux. After adding external reflux, the actual inlet TU value is reduced to 7-8, and the biological toxicity of the wastewater is reduced from high toxicity (10≤TU<100) to the poisoning level (1≤TU<10), the biological toxicity is greatly reduced, and the biochemical treatment efficiency is improved. Compared with the integrated and non-integrated devices with external reflux, under the condition of controlling the same effluent indicators, the integrated device has a small footprint and low investment and operation costs through the intensive treatment of the treatment device. Therefore, the present invention realizes the efficient, stable and low-cost treatment of high-salt toxic wastewater, and has a better technical effect.

[0114] The above embodiments are merely descriptions of preferred implementation modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A biochemical-ozone oxidation-biochemical coupling treatment method for high-salt toxic wastewater, characterized in that: The following steps are involved: The high-salinity toxic wastewater after oil removal and sedimentation pretreatment is treated in sequence through two-stage biochemical-ozone oxidation-biochemical coupling units. Each unit includes an anoxic tank, a sedimentation tank, an ozone oxidation tank and an aerobic tank connected in series: Primary anoxic tank: denitrification and degradation of biodegradable COD; Primary sedimentation tank: to separate mud and water and remove SS and colloids; Primary ozone oxidation pool: treats refractory COD, reduces toxicity and improves biodegradability; Primary aerobic pool: degrades COD, nitrifies ammonia nitrogen, and the effluent from the primary aerobic pool is internally refluxed to the primary denitrification pool, with an internal reflux ratio of 100% to 300%; Secondary anoxic tank: for denitrification; Secondary sedimentation tank: to separate mud and water and remove SS and colloids; Secondary ozone oxidation pool: treats refractory COD and further reduces toxicity; Secondary aerobic pool: used to ensure that the effluent COD and NH3-N meet the standards, and the effluent of the secondary aerobic pool is returned to the primary anoxic pool, and the external return ratio is 100%~300%; After the above treatment, the wastewater has COD≤50mg / L, ammonia nitrogen≤5mg / L, and total nitrogen≤15mg / L.

2. The biochemical-ozone oxidation-biochemical coupling treatment method for high-salt toxic wastewater according to claim 1 is characterized in that: The primary aerobic effluent is returned to the primary ozone oxidation tank for ozone jet addition, and the reflux ratio is 50% to 150%; the secondary aerobic tank effluent is returned to the secondary ozone oxidation tank for ozone jet addition, and the reflux ratio is 100% to 300%.

3. The biochemical-ozone oxidation-biochemical coupling treatment method for high-salt toxic wastewater according to claim 1 is characterized in that: The first-level anoxic pool is divided into three compartments, and the dissolved oxygen in the first compartment does not exceed 0.2 mg / L, the dissolved oxygen in the second compartment does not exceed 0.8 mg / L, and the dissolved oxygen in the third compartment is 1.0~1.5 mg / L.

4. The method for treating high-salt toxic wastewater by biochemical-ozone oxidation-biochemical coupling according to claim 1, characterized in that: The primary ozone oxidation tank adopts ozone contact oxidation process or ozone / H2O2 process, and the secondary ozone oxidation tank adopts ozone / H2O2 process; and the ozone dosage is 20~200mg / L, and the H2O2 dosage is 30%~70% of the ozone dosage.

5. The method for treating high-salt toxic wastewater by biochemical-ozone oxidation-biochemical coupling according to claim 1 or 2, characterized in that: The primary aerobic pool is divided into three compartments, and the effluent from the third compartment of the primary aerobic pool flows back to the primary anoxic pool, and the effluent from the first compartment of the primary aerobic pool flows back to the primary ozone oxidation pool for ozone jet addition.

6. The high-salinity toxic wastewater biochemical-ozone oxidation-biochemical coupling treatment method according to claim 1 is characterized by: The primary anoxic tank, the primary aerobic tank, the secondary anoxic tank and the secondary aerobic tank all adopt a biofilm process; moreover, the biofilm process is one of a contact oxidation process, an MBBR process or an MBR process.

7. The method for treating high-salt toxic wastewater by biochemical-ozone oxidation-biochemical coupling according to claim 1, characterized in that: The first-level anoxic tank, the first-level aerobic tank, the second-level anoxic tank, and the second-level aerobic tank are added with salt-tolerant bacteria; the residual sludge discharged from the first-level sedimentation tank and the second-level sedimentation tank enters the salt-tolerant bacteria culture system, and the culture time is not less than 24 hours; the first-level sedimentation tank and the second-level sedimentation tank are preferably high-density sedimentation tanks.

8. The high-salt toxic wastewater biochemical-ozone oxidation-biochemical coupling treatment method according to claim 1 is characterized in that: It also includes a salt-tolerant bacteria culture system, which adopts an A / O process; the inlet water of the culture pool is the effluent from a secondary aerobic pool and has a salinity of not less than 2%; the A / O pool culture process parameters are: temperature 20-35°C, pH 7.5-8.5, dissolved oxygen in pool A is less than 0.3 mg / L, and dissolved oxygen in pool O is greater than 2 mg / L, and the carbon source and nutrition required for culture are composed of one or more of glucose, methanol, sodium acetate, sucrose, corn syrup powder, molasses, yeast powder, biological promoter, and potassium chloride.

9. The method for treating high-salt toxic wastewater by biochemical-ozone oxidation-biochemical coupling according to claim 1, characterized in that: The high-salinity toxic wastewater refers to wastewater with high salinity, high organic matter content and high toxicity, which specifically meets the following characteristics: (1) Salinity: TDS>10000mg / L or conductivity>15000μS / cm; (2) Organic matter content: COD>500mg / L; (3) Toxicity: According to the "toxicity unit (TU)" value of the U.S. EPA, the toxicity unit classification standard is divided into four levels: wastewater grade IV, 10≤TU<100, highly toxic; (4) Biochemical properties: B / C<0.

3.

10. The high-salinity toxic wastewater biochemical-ozone oxidation-biochemical coupling treatment method according to claim 1 is characterized by: After the above treatment, the wastewater has COD≤30mg / L, ammonia nitrogen≤1mg / L, and total nitrogen≤5mg / L.

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