Wastewater sludge treatment system and treatment method

Abstract

The invention discloses a wastewater sludge treatment system and method, and belongs to the technical field of municipal wastewater and sludge treatment. According to the technical scheme, the method comprises the following steps: treating wastewater by virtue of an ozone oxidation zone until the BOD5 / COD index is 0.4-0.6, treating the wastewater by virtue of a first aerobic zone, a first anoxic zone, a second aerobic zone and a second anoxic zone in sequence, and discharging the treated wastewater into a sedimentation tank; part of the sludge in the sedimentation tank and the sludge in the first aerobic zone and the second aerobic zone flow back to the lateral flow enhanced fermentation zone, are fermented in an anaerobic environment of the lateral flow enhanced fermentation zone, and are discharged into the first anoxic zone and the second anoxic zone after being subjected to photocatalytic oxidation treatment of Fe3O4 and TiO2 in the lateral flow enhanced fermentation zone until the C / N is 5.0-6.0 and the oxidation-reduction potential is less than or equal to-50 mV. The method is applied to the aspect of municipal sewage and sludge treatment, effective treatment of refractory COD and effective sludge reduction can be achieved, carbon source supply of the system is optimized, effective enrichment of functional microorganisms is promoted, and advanced treatment of COD, nitrogen and phosphorus is achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of municipal sewage and sludge treatment, and in particular relates to a wastewater sludge treatment system and a treatment method. Background Art

[0002] At present, the treatment of difficult-to-degrade and high-concentration COD wastewater has always been a difficult problem in the field of municipal wastewater treatment. Water bodies such as industrial wastewater, landfill leachate, aquaculture wastewater and pharmaceutical wastewater generally have high COD concentrations and are difficult to degrade. Therefore, in the absence of sufficient available carbon sources, subsequent biological treatment cannot fully play its role, and the nitrogen and phosphorus in the wastewater cannot be deeply treated. If the water that cannot be deeply treated is discharged into the environment, it will cause environmental problems such as eutrophication of the water body.

[0003] In addition, the current biological treatment process for treating high-concentration and difficult-to-degrade COD wastewater has low efficiency. The difficult-to-degrade organic matter in many sewages has a stable structure and is difficult to effectively degrade by conventional biological treatment. Although the anaerobic fermentation process can remove some difficult-to-degrade organic matter, the fermentation rate is slow and the treatment efficiency is not high. Although advanced oxidation can achieve effective removal, it consumes a lot of energy while achieving deep removal. Therefore, a single process is often difficult to meet the treatment requirements, and the use of a combination of multiple processes has become an effective way to treat this type of wastewater, and the combined process can be synergistically optimized through continuous adjustment. Summary of the invention

[0004] In view of the shortcomings of the prior art, the present invention solves at least one of the above-mentioned technical problems and proposes a wastewater sludge treatment system and method that can effectively treat difficult-to-degrade COD and effectively reduce sludge, optimize the carbon source supply of the system, promote the effective enrichment of functional microorganisms and achieve deep treatment of COD, nitrogen and phosphorus.

[0005] In order to solve the technical problem, the technical solution adopted by the present invention is: The present invention provides a method for treating wastewater sludge, comprising: treating wastewater in an ozone oxidation zone until BOD 5 After the COD index reaches 0.4-0.6, it is discharged into the sedimentation tank after being treated in the first aerobic zone, the first anoxic zone, the second aerobic zone, and the second anoxic zone in sequence; part of the sludge in the sedimentation tank and the sludge in the first aerobic zone and the second aerobic zone are returned to the side stream enhanced fermentation zone, where they are fermented in the anaerobic environment. 3 O 4 @TiO 2 After photocatalytic oxidation treatment until C / N is 5.0-6.0 and redox potential is ≤-50 mV, it is discharged into the first anoxic zone and the second anoxic zone.

[0006] Preferably, the wastewater is treated in the ozone oxidation zone until the COD removal rate is ≥30% and the total toxicity equivalent TEQ is ≤1.0, and then is discharged into the sedimentation tank after being treated in the first aerobic zone, the first anoxic zone, the second aerobic zone, and the second anoxic zone.

[0007] Preferably, part of the sludge in the sedimentation tank and the sludge in the first aerobic zone and the second aerobic zone are returned to the side stream enhanced fermentation zone, and fermented in the anaerobic environment of the side stream enhanced fermentation zone. 3 O 4 @TiO 2 After photocatalytic oxidation treatment until the proportion of small molecular organic matter is ≥60%, it is discharged into the first anoxic zone and the second anoxic zone; the molecular weight of small molecular organic matter is <1 kDa.

[0008] Preferably, the volume ratio of the first aerobic zone, the first anoxic zone, the second aerobic zone, and the second anoxic zone is 2:2:2:3.

[0009] Preferably, part of the sludge in the sedimentation tank is discharged from the system through the sludge discharge port, part of the sludge is returned to the first aerobic zone, and part of the sludge is returned to the side stream enhanced fermentation zone.

[0010] On the other hand, the present invention provides a wastewater sludge treatment system for the wastewater sludge treatment method described in any of the above technical solutions, comprising: an inlet tank, an ozone oxidation zone, a first aerobic zone, a first anoxic zone, a second aerobic zone, a second anoxic zone, and a sedimentation tank connected in sequence; and a side stream enhanced fermentation zone; a mud outlet of the sedimentation tank is connected to the side stream enhanced fermentation zone, the mud outlets of the first aerobic zone and the second aerobic zone are connected to the side stream enhanced fermentation zone, and the outlet of the side stream enhanced fermentation zone is connected to the first anoxic zone and the second anoxic zone.

[0011] Preferably, it also includes an ozone generator connected to the ozone oxidation zone for providing ozone to the ozone oxidation zone; and an aeration head arranged in the first aerobic zone and the second aerobic zone, the aeration head being connected to an air pump.

[0012] Preferably, it also includes a stirring device for stirring the first anoxic zone and the second anoxic zone.

[0013] Preferably, it also includes a wave maker arranged in the lateral flow enhanced fermentation area.

[0014] Preferably, the water inlet tank, the ozone oxidation zone, the first aerobic zone, the first anoxic zone, the second aerobic zone, the second anoxic zone, the sedimentation tank, and the side stream enhanced fermentation zone are connected by a pipeline, and a water pump or a mud pump is provided on the pipeline.

[0015] Compared with the prior art, the present invention has the following beneficial effects: The present invention provides a method for treating wastewater sludge, which treats such wastewater in a coordinated manner of "advanced oxidation-biological treatment-photocatalysis". An ozone oxidation zone is set at the head end to preliminarily treat the COD in the influent, preliminarily degrade pollutants such as difficult-to-degrade organic compounds, and then deeply remove them in an aerobic zone with high sludge concentration, degrading the difficult-to-degrade organic compounds into small molecular carbon sources, and solving the problem of sludge aging by receiving the discharged sludge from the sedimentation tank. At the same time, the side stream enhanced fermentation zone provides sufficient carbon source for subsequent biological treatment, avoiding the competition between denitrifying bacteria and polyphosphate bacteria for carbon source in the anaerobic section, and adding Fe to the strict anaerobic environment. 3 O 4 @TiO 2 Achieve high-efficiency sludge reduction and solve the problems caused by sludge load. A longer anoxic section is set at the last section of the mainstream system. Through the above settings, deep removal of COD, nitrogen and phosphorus in the system is achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 A schematic diagram of the structure of a wastewater sludge treatment system provided by an embodiment of the present invention; Figure 2 A schematic diagram of the change of COD concentration of inlet and outlet water during actual operation of the wastewater sludge treatment system provided in Example 1 of the present invention; Figure 3 A schematic diagram of changes in nitrogen and phosphorus concentrations in inlet and outlet water during actual operation of the wastewater sludge treatment system provided in Example 1 of the present invention; Figure 4 A schematic diagram of the change of COD concentration of inlet and outlet water during actual operation of the wastewater sludge treatment system provided in Example 2 of the present invention; Figure 5 A schematic diagram of changes in nitrogen and phosphorus concentrations in inlet and outlet water during actual operation of the wastewater sludge treatment system provided in Example 2 of the present invention; In the above figures: 1. water inlet tank; 2. ozone oxidation zone; 3. first aerobic zone; 4. first anoxic zone; 5. second aerobic zone; 6. second anoxic zone; 7. sedimentation tank; 8. side stream enhanced fermentation zone; 9. ozone generator; 10. stirring device. DETAILED DESCRIPTION

[0017] The technical scheme in the specific embodiment of the present invention will be described in detail and completely in conjunction with the accompanying drawings. Obviously, the described embodiments are only some specific implementation methods of the overall technical scheme of the present invention, rather than all implementation methods. Based on the overall concept of the present invention, all other embodiments obtained by ordinary technicians in this field fall within the scope of protection of the present invention.

[0018] The present invention provides a method for treating wastewater sludge, comprising: treating wastewater in an ozone oxidation zone 2 until BOD 5 After the COD index reaches 0.4-0.6, the sludge is sequentially treated in the first aerobic zone 3, the first anoxic zone 4, the second aerobic zone 5, and the second anoxic zone 6 and then discharged into the sedimentation tank 7; part of the sludge in the sedimentation tank 7 and the sludge in the first aerobic zone 3 and the second aerobic zone 5 are returned to the side stream enhanced fermentation zone 8, and fermented in the anaerobic environment of the side stream enhanced fermentation zone 8; at the same time, the sludge in the side stream enhanced fermentation zone 8 is treated with Fe 3 O 4 @TiO 2 After the photocatalytic oxidation treatment is carried out until the C / N ratio is 5.0-6.0 and the redox potential is ≤-50 mV, it is discharged into the first anoxic zone 4 and the second anoxic zone 6.

[0019] The above wastewater sludge treatment method is a Fe-based 3 O 4 @TiO 2 The high-concentration difficult-to-degrade COD wastewater treatment system and sludge reduction method of catalytic fermentation and advanced oxidation coupled side-stream enhanced fermentation treats this type of wastewater in a coordinated manner of "advanced oxidation-biological treatment-photocatalysis". An ozone oxidation zone 2 is set at the head end to preliminarily treat the COD in the influent and preliminarily degrade pollutants such as difficult-to-degrade organic compounds. Subsequently, deep removal is performed in the aerobic zone with high sludge concentration to degrade difficult-to-degrade organic compounds into small molecular carbon sources, and the problem of sludge aging is solved by receiving the sludge discharged from the sedimentation tank 7. At the same time, the side-stream enhanced fermentation zone 8 provides sufficient carbon sources for subsequent biological treatment, avoiding the competition between denitrifying bacteria and polyphosphate bacteria for carbon sources in the anaerobic section, and adding Fe to the strict anaerobic environment. 3 O 4 @TiO 2 Achieve high-efficiency sludge reduction and solve the problems caused by sludge load. A longer anoxic section is set at the last section of the mainstream system. Through the above settings, deep removal of COD, nitrogen and phosphorus in the system is achieved. Specifically, The above technical solution limits the placement of the ozone treatment unit at the front end to (1) improve biodegradability. If the biological treatment is placed at the front end, after the influent enters the biological treatment, the carbon source is difficult to utilize and the COD is difficult to degrade. The functional microorganisms cannot carry out normal life activities, and the biological treatment system cannot operate stably for a long time. If the ozone treatment unit is placed at the front end, the ozone treatment unit can decompose the difficult-to-degrade macromolecular organic matter into small molecular intermediates for microorganisms to utilize, thereby ensuring the normal operation of the entire system. (2) Relieve biological inhibition. If the ozone treatment unit is placed at the front end, it can degrade or transform toxic substances and avoid inhibition of microorganisms. (3) Shorten the biological treatment residence time. The biodegradability of the sewage treated by the ozone treatment unit is improved, and the hydraulic retention time of the bioreactor can be shortened. (4) If the ozone treatment unit is placed at the rear end, the COD in the influent cannot be effectively utilized in the biological treatment stage, and the COD treatment is still concentrated in the rear ozone treatment unit, which consumes extremely high energy. At the same time, the biological treatment unit cannot effectively remove nitrogen and phosphorus. Placing the ozone treatment unit at the front end effectively solves the above problems. The ozone treatment unit moderately treats the influent, improves its biodegradability, and performs deep treatment in the biological treatment stage, reducing energy consumption. It can be seen that placing the ozone oxidation zone 2 at the front end of the biological treatment zone can initially degrade the difficult-to-degrade complex organic matter, and the untreated COD wastewater will be removed in the subsequent biological treatment. The combination of advanced oxidation process and biological treatment not only saves the energy consumption of advanced oxidation process for deep treatment of COD wastewater, but also makes up for its inability to perform denitrification and denitrification.

[0020] The above technical solution defines the photocatalyst Fe 3 O 4 @TiO 2 The reason for adding it to the sidestream fermentation area, rather than other areas, is that the sludge concentration in the sidestream fermentation area is high. The addition of photocatalysts can promote the generation of VFA in the sidestream fermentation area and improve the sludge reduction efficiency. This design not only avoids the interference of photocatalysis on the main process, but also gives full play to the synergistic effect of photocatalysis-fermentation. It is a balanced choice of technical feasibility and engineering practicality. 3 O 4 @TiO 2 TiO 2 Under light conditions, active oxygen free radicals can be generated to destroy the sludge floc structure and degrade refractory organic matter. 3 O 4 @TiO 2 Fe 3 O 4 Using its conductivity to quickly transfer TiO 2 The electrons carried in the sludge can reduce the recombination, improve the photocatalytic efficiency in the system, improve the fermentation efficiency, achieve deep sludge reduction, and utilize Fe3 O 4 The magnetic properties of Fe 3 O 4 @TiO 2 Recycling can reduce material loss and secondary pollution. In addition, the microorganisms in the side stream enhanced fermentation zone 8 utilize Fe 3 O 4 @TiO 2 Electrons or H generated by photocatalysis 2 O 2 Participate in its own metabolism and enhance its fermentation ability. At the same time, functional microorganisms can 3 O 4 @TiO 2 The surface is attached and a biofilm is formed, which shortens the substrate transfer distance, improves the reaction efficiency, strengthens the fermentation capacity, forms a "photocatalytic-biological treatment" collaborative innovation path, and achieves effective sludge reduction.

[0021] In addition, the above technical solution also stipulates that the wastewater is treated in the ozone oxidation zone 2 until the BOD 5 / COD index is 0.4-0.6 before entering the first aerobic zone 3. The reason is that if BOD 5 / COD index is less than 0.4, the refractory organic matter is not fully converted into easily degradable substances, the subsequent aerobic and other biological treatment stages are inefficient, and the carbon source cannot be fully utilized to remove pollutants; if BOD 5 If the COD index is higher than 0.6, it may lead to excessive mineralization of organic matter (generating carbon dioxide and water, etc.), which not only wastes energy but also leads to a lack of carbon source for biological treatment.

[0022] Furthermore, the above technical solution also defines the Fe 3 O 4 @TiO 2 After photocatalytic oxidation treatment to C / N of 5.0-6.0 and redox potential ≤-50 mV, it is discharged into the first anoxic zone 4 and the second anoxic zone 6. The reason is that if the C / N is low, the carbon source produced by photocatalysis and anaerobic fermentation is low, and denitrification in the anoxic zone is limited due to insufficient carbon source, resulting in accumulation of nitrate nitrogen; ORP that is too high (too strong oxidizing property) will inhibit the activity of denitrifying bacteria, and the degree of oxidation of organic matter needs to be regulated by photocatalysis.

[0023] The above-mentioned wastewater sludge treatment method is set as an aerobic zone at the head end of biological treatment, and the sludge concentration is relatively high. The high biological activity of the aerobic zone is used to further degrade the COD that has not reached deep treatment in the ozone oxidation stage, and the energy consumption of deep and complete treatment of COD in the influent in the ozone oxidation stage is saved. In addition, the side stream enhanced fermentation zone 8 receives sludge from the end of the aerobic zone and the sedimentation tank 7, and performs sludge reduction in a deep anaerobic environment. At the same time, the carbon source generated by the sludge fermentation is supplemented to the first section of the anoxic zone, promoting the synthesis of internal carbon sources by functional microorganisms, avoiding the competition of polyphosphate bacteria and denitrifying bacteria for carbon sources, and optimizing the distribution of carbon sources.

[0024] In a preferred embodiment, the wastewater is treated in the ozone oxidation zone 2 until the COD removal rate is ≥30% and the total toxic equivalent TEQ is ≤1.0, and then is treated in the first aerobic zone 3, the first anoxic zone 4, the second aerobic zone 5, and the second anoxic zone 6 in sequence and then discharged into the sedimentation tank 7. If the total toxic equivalent is too high, it will affect the activity of subsequent biological treatment.

[0025] In a preferred embodiment, part of the sludge in the sedimentation tank 7 and the sludge in the first aerobic zone 3 and the second aerobic zone 5 are returned to the side stream enhanced fermentation zone 8, and fermented in the anaerobic environment of the side stream enhanced fermentation zone 8. 3 O 4 @TiO 2 After the photocatalytic oxidation treatment to small molecule organic matter accounted for ≥60%, it was discharged into the first anoxic zone 4 and the second anoxic zone 6; the molecular weight of small molecule organic matter was less than 1 kDa. A higher concentration of small molecule organic matter is more conducive to the utilization of denitrifying bacteria and improves the denitrification rate.

[0026] In a preferred embodiment, the volume ratio of the first aerobic zone 3, the first anoxic zone 4, the second aerobic zone 5, and the second anoxic zone 6 is 2:2:2:3. The second anoxic zone 6 has a long section, and the long section of the anoxic zone is conducive to deep removal of nitrate nitrogen in the water, making up for the deficiency that the ozone oxidation zone 2 cannot perform denitrification and denitrification, and at the same time achieving deep denitrification.

[0027] In a preferred embodiment, part of the sludge in the sedimentation tank 7 is discharged from the system through the sludge outlet, part of the sludge is returned to the first aerobic zone 3, and part of the sludge is returned to the side stream enhanced fermentation zone 8. Part of the sludge in the sedimentation tank 7 is returned to the aerobic zone to solve the sludge aging problem caused by the aerobic state of the aerobic zone for a long time, while maintaining a high sludge concentration and maintaining a high biological activity.

[0028] Another aspect of the present invention provides a wastewater sludge treatment system for use in the wastewater sludge treatment method described in any of the above technical solutions, such as Figure 1As shown, it includes: an inlet water tank 1, an ozone oxidation zone 2, a first aerobic zone 3, a first anoxic zone 4, a second aerobic zone 5, a second anoxic zone 6, a sedimentation tank 7, and a side stream enhanced fermentation zone 8, which are connected in sequence; a mud outlet of the sedimentation tank 7 is connected to the side stream enhanced fermentation zone 8, mud outlets of the first aerobic zone 3 and the second aerobic zone 5 are connected to the side stream enhanced fermentation zone 8, and an outlet of the side stream enhanced fermentation zone 8 is connected to the first anoxic zone 4 and the second anoxic zone 6. Each unit is separated by a partition wall or connected by a pipeline.

[0029] In a preferred embodiment, it also includes an ozone generator 9 connected to the ozone oxidation zone 2 for providing ozone to the ozone oxidation zone 2; and an aeration head arranged in the first aerobic zone 3 and the second aerobic zone 5, the aeration head is connected to the air pump, and the aeration amount is controlled by a flow meter respectively, and aeration is achieved by the air pump.

[0030] In a preferred embodiment, it also includes a stirring device 10 for stirring the first anoxic zone 4 and the second anoxic zone 6 , and a wave maker disposed in the lateral flow enhanced fermentation zone 8 .

[0031] The above-mentioned ozone generator 9, stirring device 10, air pump, wave maker, water pump, and mud pump are all controlled and operated by a PLC control system. In order to realize the control of the PLC control system, the relevant components are connected through electrical connections to realize signal transmission. The PLC control system can be a PLC controller or other control modules.

[0032] In a preferred embodiment, the water inlet tank 1, the ozone oxidation zone 2, the first aerobic zone 3, the first anoxic zone 4, the second aerobic zone 5, the second anoxic zone 6, the sedimentation tank 7, and the side stream enhanced fermentation zone 8 are connected by pipelines, and a water pump or a mud pump is provided on the pipeline. Specifically, the water inlet tank 1 is connected to the ozone oxidation zone 2 through the water inlet pipe and the water pump, the ozone generator 9 is connected to the ozone oxidation device through the air inlet pipe and provides ozone, the ozone oxidation zone 2 is connected to the first aerobic zone 3 through the pipe and the water pump, the second anoxic zone 6 is connected to the sedimentation tank 7 through the outlet pipe and the water pump, the sedimentation tank 7 is connected to the side stream enhanced fermentation zone 8 through the mud discharge pipe and the mud pump, the sedimentation tank 7 is connected to the aerobic zone through the mud discharge pipe and the mud pump, the side stream enhanced fermentation zone 8 is connected to the anoxic zone through the drainage pipe and the water pump, the side stream enhanced fermentation zone 8 is connected to the anoxic zone through the drainage pipe and the water pump, the aerobic zone is connected to the side stream enhanced fermentation zone 8 through the mud discharge pipe and the mud pump, and the aerobic zone discharges mud through the mud discharge pipe and the mud pump and is connected to the side stream enhanced fermentation zone 8.

[0033] The above system realizes the synergistic effect of "advanced oxidation-biological treatment-photocatalysis" through the joint action of ozone oxidation, biological treatment and side-stream enhanced fermentation. It uses innovative technology to achieve deep removal of high-concentration and difficult-to-degrade COD and nitrogen and phosphorus in the system, and achieves effective sludge reduction.

[0034] The working process of the above wastewater sludge treatment system is: The influent enters the ozone oxidation zone 2 from the influent tank 1 through a water pump. The ozone generator 9 will continuously provide ozone to preliminarily degrade the pollutants such as COD in the influent. The influent enters the first aerobic zone 3 through a water pump. The high concentration of activated sludge and aerobic conditions in the first aerobic zone 3 will further degrade the COD that is difficult to decompose. At the same time, the first aerobic zone 3 will remove the remaining NH 4 + -N is converted to NO 2 - -N and NO 3 - -N, then the denitrifying bacteria and polyphosphate bacteria in the activated sludge in the first anoxic zone 4 will use the sufficient carbon source to carry out denitrification and store the internal carbon source, and then carry out secondary nitrification reaction and aerobic phosphorus absorption reaction in the second aerobic zone 5, and discharge sludge at the end of the second aerobic zone 5 to remove phosphorus in the sewage, and then the treated water enters the second anoxic zone 6, and the second anoxic zone 6 carries out secondary denitrification and deep treatment of denitrification.

[0035] The water treated by the system will enter the sedimentation tank 7 through the water pump, and the treated water after sedimentation will be discharged through the outlet. Part of the activated sludge at the bottom of the sedimentation tank 7 will be discharged from the system, part will flow back to the aerobic zone, and part will flow back to the side stream enhanced fermentation zone 8.

[0036] The side stream enhanced fermentation zone 8 will reduce the sludge discharged from the first aerobic zone 3, the second aerobic zone 5 and the sedimentation tank 7 under anaerobic conditions, and at the same time, the fermentation liquid in the side stream enhanced fermentation zone 8 will be supplemented to the first anoxic zone 4 and the second anoxic zone 6 through a water pump to supplement the carbon source. The anaerobic environment of the side stream enhanced fermentation zone 8 and the Fe 3 O 4 @TiO 2 The photocatalytic effect is used to deeply reduce the sludge. The whole system realizes the synergistic effect of "advanced oxidation-biological treatment-photocatalysis" through the joint action of ozone oxidation, biological treatment and side stream enhanced fermentation, and realizes the deep removal of high-concentration and difficult-to-degrade COD and nitrogen and phosphorus in the system.

[0037] Specifically include: Step 1: The influent enters the ozone oxidation zone 2 through a water pump in the influent tank 1. The first aerobic zone 3 is equipped with an aeration head for aeration. Under aerobic conditions, the activated sludge has high biological activity, which hydrolyzes the refractory macromolecular carbon source in the influent into small molecular usable carbon sources. 4 + -N is converted to NO 2 - -N and NO 3 - -N. In the first anoxic zone 4, the anoxic conditions will reduce the NO2 - -N and NO 3 - -N Restore to N 2 At the same time, the first anoxic zone 4 receives the fermentation liquid from the side stream enhanced fermentation zone 8 to supplement the carbon source in the influent, providing sufficient carbon source for the survival of denitrifying bacteria and polyphosphate bacteria, and the first anoxic zone 4 is equipped with a stirring device 10 to keep the activated sludge in the first anoxic zone 4 fully mixed. Then the sewage enters the second aerobic zone 5, which is equipped with an aeration head. Under aerobic conditions, the activated sludge will convert NH 4 + -N is further oxidized to NO 2 - -N and NO 3 - -N, deep removal of NH in the influent 4 + -N, while the polyphosphate bacteria utilize the internal carbon source synthesized in the first anoxic zone 4 to fully and excessively absorb phosphorus under aerobic conditions, and discharge the sludge through the sludge pump to remove PO in the system 4 3- -P, part of the sludge discharged from the second aerobic zone 5 is discharged from the system, and part is discharged to the side stream enhanced fermentation zone 8. Then the influent enters the second anoxic zone 6, which is equipped with a stirring device 10. The COD and NO in the influent are finally removed through the longer anoxic zone. 2 - -N and NO 3 - -N.

[0038] Step 2: The treated water enters the sedimentation tank 7 through a water pump for subsequent treatment. The precipitated water is discharged through the outlet. Part of the activated sludge after the bottom sedimentation is discharged from the system through the sludge outlet, part of it is returned to the aerobic zone through the mud pump to maintain the high sludge concentration state in the aerobic zone, and part of it is returned to the side stream enhanced fermentation zone 8.

[0039] Step 3: The side stream enhanced fermentation zone 8 maintains a strict anaerobic environment and adds Fe 3 O 4 @TiO 2 In order to enhance its fermentation efficiency, a wave maker is configured. When the system is running, the side flow enhanced fermentation zone 8 provides sludge fermentation liquid and functional microorganisms to the front ends of the first anoxic zone 4 and the second anoxic zone 6 respectively, and at the same time receives sludge from the first aerobic zone 3, the second aerobic zone 5 and the sedimentation tank 7 to reduce the sludge.

[0040] It should be noted that the above-mentioned wastewater sludge treatment system is composed of an ozone oxidation device, a biological treatment process and a side stream enhanced fermentation device. Many types of sewage or wastewater have high COD concentrations and are difficult to degrade, such as pharmaceutical wastewater, food processing wastewater and papermaking wastewater. Advanced oxidation processes such as ozone oxidation require large amounts of energy to treat some wastewater, and pollutants such as nitrate nitrogen in the water are difficult to remove. Traditional biological processes have a low removal rate for difficult-to-degrade organic matter, and will produce a large amount of sludge, increasing operating costs. Although the side stream fermentation process can achieve a certain amount of sludge reduction, the decomposition rate of microorganisms themselves under normal anaerobic conditions is low, so the sludge reduction effect is weak. By using Fe-based 3 O 4 @TiO 2 The high-concentration difficult-to-degrade COD wastewater treatment system and sludge reduction method of catalytic fermentation and advanced oxidation coupled side-stream enhanced fermentation effectively solve the above problems.

[0041] In order to more clearly and in detail introduce the wastewater sludge treatment system and treatment method provided by the embodiments of the present invention, they will be described below in conjunction with specific embodiments.

[0042] Example 1 Using the aforementioned inventive device, this embodiment is implemented in a laboratory using laboratory water distribution and according to the following steps: 1) The average COD concentration of the influent is 1300 mg / L, of which PAHs account for 25%, phenolic compounds account for 10%, TN concentration is 57 mg / L, TP concentration is 8.6 mg / L, and the water temperature is 25°C. The sewage enters the ozone oxidation zone 2 from the influent tank 1 through a water pump and is treated to BOD 5 After the / COD index is 0.4, the COD removal rate is ≥30%, and the total toxicity equivalent TEQ is ≤1.0, it enters the first aerobic zone 3 through a water pump. The sludge concentration in the first aerobic zone 3 is 13200 mg / L and the dissolved oxygen concentration is 4.5 mg / L.

[0043] 2) After the sewage is treated in the aerobic stage, it enters the first anoxic zone 4. The rotation speed of the stirring device 10 is 100 rpm. At the same time, the first anoxic zone 4 receives the fermentation liquid from the side stream enhanced fermentation zone 8, and the dissolved oxygen concentration is 0.3 mg / L and the sludge concentration is 8650 mg / L.

[0044] 3) After that, the sewage enters the second aerobic zone 5, the dissolved oxygen concentration is 4.5 mg / L, the sludge concentration is 7560 mg / L, and the sludge is discharged at the end of the second aerobic zone 5, part of the discharged sludge is discharged from the system, and part enters the side stream enhanced fermentation zone 8.

[0045] 4) Afterwards, the sewage enters the longer second anoxic zone 6 for final treatment, with a sludge concentration of 5530 mg / L, a rotation speed of the stirring device 10 of 100 rpm, and a dissolved oxygen concentration of 0.2 mg / L.

[0046] 5) After that, the sewage enters the sedimentation tank 7 through a water pump, and the effluent is discharged from the lower outlet. Part of the activated sludge after precipitation is discharged from the system, part of it is returned to the aerobic zone through a mud pump, and part of it is returned to the side stream enhanced fermentation zone 8.

[0047] 6) The side stream enhanced fermentation zone 8 provides fermentation liquid to the first anoxic zone 4 and the second anoxic zone 6 through a mud pump, and receives the sludge discharged from the first aerobic zone 3, the second aerobic zone 5 and the sedimentation tank 7, and adds Fe 3 O 4 @TiO 2 The amount is 0.8 g / L, and the sludge is reduced by enhanced fermentation under anaerobic conditions. 3 O 4 @TiO 2 After photocatalytic oxidation treatment until the C / N is 5.0, the redox potential is ≤-50 mV, and the proportion of small molecular organic matter is ≥60%, it is discharged into the first anoxic zone 4 and the second anoxic zone 6.

[0048] like Figure 2 , 3 As shown, the final effluent indicators are: COD = 42.5 mg / L, TN = 5.6 mg / L, TP = 0.5 mg / L, all indicators meet the Class A emission standard specified in the "Standard for Pollutant Emission Indicators for Urban Wastewater Treatment Plants (GB18918-2002)". Compared with another group of traditional biological treatment process A2O systems set up in the laboratory, the average effluent COD of the present invention is reduced by 585 mg / L, TN concentration is reduced by 21 mg / L, TP concentration is reduced by 5.6 mg / L, and the system sludge discharge is reduced by 30% compared with the traditional A2O process. Compared with the pure ozone oxidation device, the energy consumption consumed by deep COD removal is reduced by 55%.

[0049] Example 2 Using the aforementioned device of the present invention, this embodiment uses diluted wastewater from a food processing plant as influent and is implemented according to the following steps: 1) The average COD concentration in the sewage is 1865 mg / L, the TN concentration is 105 mg / L, and the TP concentration is 10.6 mg / L. The influent contains a large amount of grease, fat and other difficult-to-degrade organic compounds. The water temperature is 25°C. The sewage enters the ozone oxidation zone 2 from the influent tank 1 through a water pump and is treated to BOD 5After the / COD index is 0.6, the COD removal rate is ≥30%, and the total toxicity equivalent TEQ is ≤1.0, it enters the first aerobic zone 3 through a water pump. The sludge concentration in the first aerobic zone 3 is 11650 mg / L and the dissolved oxygen concentration is 5.2 mg / L.

[0050] 2) After the sewage is treated in the aerobic stage, it enters the first anoxic zone 4. The rotation speed of the stirring device 10 is 100 rpm. At the same time, the first anoxic zone 4 receives the fermentation liquid from the side stream enhanced fermentation zone 8. The dissolved oxygen concentration is 0.2 mg / L and the sludge concentration is 8588 mg / L.

[0051] 3) After that, the sewage enters the second aerobic zone 5, the dissolved oxygen concentration is 4.5 mg / L, the sludge concentration is 7632 mg / L, and the sludge is discharged at the end of the second aerobic zone 5, part of the discharged sludge is discharged from the system, and part enters the side stream enhanced fermentation zone 8.

[0052] 4) Afterwards, the sewage enters the second anoxic zone 6 for final treatment, the sludge concentration is 5961 mg / L, the rotation speed of the stirring device 10 is 100 rpm, and the dissolved oxygen concentration is 0.3 mg / L.

[0053] 5) After that, the sewage enters the sedimentation tank 7 through a water pump, and the effluent is discharged from the lower outlet. Part of the activated sludge after precipitation is discharged from the system, part of it is returned to the first aerobic zone 3 through a mud pump, and part of it is returned to the side stream enhanced fermentation zone 8.

[0054] 6) The side stream enhanced fermentation zone 8 provides fermentation liquid to the first anoxic zone 4 and the second anoxic zone 6 through a water pump, and receives the sludge discharged from the first aerobic zone 3, the second aerobic zone 5 and the sedimentation tank 7, and adds Fe 3 O 4 @TiO 2 The amount is 1.2g / L, and the sludge is reduced by enhanced fermentation under anaerobic conditions. 3 O 4 @TiO 2 After photocatalytic oxidation treatment until the C / N is 6.0, the redox potential is ≤-50 mV, and the proportion of small molecular organic matter is ≥60%, it is discharged into the first anoxic zone 4 and the second anoxic zone 6.

[0055] like Figure 4 , 5As shown, the final effluent indicators of the system are: COD = 47.8 mg / L, TN = 14.2 mg / L, TP = 0.4 mg / L, and all indicators meet the Class A emission standards specified in the "Standards for Pollutant Emission Indicators for Urban Wastewater Treatment Plants (GB18918-2002)". Compared with another group of traditional biological treatment process A2O systems, the average effluent COD of the present invention is reduced by 662 mg / L, the TN concentration is reduced by 39.6 mg / L, the TP concentration is reduced by 6.4 mg / L, and the system sludge discharge is reduced by 64.5% compared with the traditional A2O process. Compared with the pure ozone oxidation device, the energy consumption consumed by deep COD removal is reduced by 61.3%.

[0056] Comparative Example 1 Same as Example 1, except that the sewage is pumped from the water inlet tank 1 into the ozone oxidation zone 2 and treated to BOD 5 After the / COD index is 0.3, the COD removal rate is ≥30%, and the total toxicity equivalent TEQ is ≤1.0, it enters the first aerobic zone 3 through a water pump.

[0057] The final effluent indicators of the system are: COD = 287.3 mg / L, TN = 16.2 mg / L, TP = 2.3 mg / L. The biodegradable residue is too low to effectively utilize COD.

[0058] Comparative Example 2 Same as Example 1, except that the sewage is pumped from the water inlet tank 1 into the ozone oxidation zone 2 and treated to BOD 5 After the / COD index is 0.7, the COD removal rate is ≥30%, and the total toxicity equivalent TEQ is ≤1.0, it enters the first aerobic zone 3 through a water pump.

[0059] The final effluent indicators of the system are: COD = 38.2 mg / L, TN = 23.1 mg / L, TP = 5.5 mg / L. The biodegradability is too high, the energy consumption is high, and the carbon source is wasted.

[0060] Comparative Example 3 Same as Example 1, except that after the lateral flow enhanced fermentation zone 8, Fe 3 O 4 @TiO 2 After photocatalytic oxidation treatment until C / N is 4.0, redox potential ≤-50 mV, and small molecule organic matter accounts for ≥60%, it is discharged into the first anoxic zone 4 and the second anoxic zone 6.

[0061] The final effluent indicators of the system are: COD = 47.3 mg / L, TN = 15.4 mg / L, TP = 5.7 mg / L. The carbon source is less, which affects the biological treatment stage.

[0062] Comparative Example 4 Same as Example 1, except that after the lateral flow enhanced fermentation zone 8, Fe 3 O 4 @TiO 2 After photocatalytic oxidation treatment until the C / N is 7.0, the redox potential is ≤-50 mV, and the proportion of small molecular organic matter is ≥60%, it is discharged into the first anoxic zone 4 and the second anoxic zone 6.

[0063] The final effluent indicators of the system are: COD = 43.1 mg / L, TN = 8.8 mg / L, TP = 1.5 mg / L. The carbon source is too high, resulting in carbon source waste and easy sludge expansion.

[0064] Comparative Example 5 Same as Example 1, except that after the lateral flow enhanced fermentation zone 8, Fe 3 O 4 @TiO 2 After photocatalytic oxidation treatment to a C / N ratio of 5.0, a redox potential of -40 mV, and a small molecule organic matter ratio of ≥60%, the matter is discharged into the first anoxic zone 4 and the second anoxic zone 6.

[0065] The final effluent indicators of the system are: COD = 55.1 mg / L, TN = 25.6 mg / L, TP = 0.9 mg / L. Inhibit the activity of denitrifying bacteria.

Claims

1. A method for treating wastewater sludge, characterized in that: include: After the wastewater is treated in the ozone oxidation zone to a BOD5 / COD index of 0.4-0.6, it is discharged into the sedimentation tank after being treated in the first aerobic zone, the first anoxic zone, the second aerobic zone, and the second anoxic zone in sequence; Part of the sludge in the sedimentation tank and the sludge in the first aerobic zone and the second aerobic zone are returned to the side stream enhanced fermentation zone, where they are fermented under the anaerobic environment. At the same time, they are treated with photocatalytic oxidation of Fe3O4@TiO2 in the side stream enhanced fermentation zone until the C / N ratio is 5.0-6.0 and the redox potential is ≤-50 mV, and then discharged into the first anoxic zone and the second anoxic zone.

2. The method for treating wastewater sludge according to claim 1, characterized in that: After the wastewater is treated in the ozone oxidation zone to a COD removal rate of ≥30% and a total toxic equivalent TEQ ≤1.0, it is sequentially treated in the first aerobic zone, the first anoxic zone, the second aerobic zone, and the second anoxic zone before being discharged into the sedimentation tank.

3. The method for treating wastewater sludge according to claim 1, characterized in that: Part of the sludge in the sedimentation tank and the sludge in the first aerobic zone and the second aerobic zone are returned to the side stream enhanced fermentation zone, where they are fermented under the anaerobic environment. At the same time, they are treated with photocatalytic oxidation by Fe3O4@TiO2 in the side stream enhanced fermentation zone until the proportion of small molecular organic matter is ≥60%, and then discharged into the first anoxic zone and the second anoxic zone; the molecular mass of small molecular organic matter is <1 kDa.

4. The method for treating wastewater sludge according to claim 1, characterized in that: The volume ratio of the first aerobic zone, the first anoxic zone, the second aerobic zone, and the second anoxic zone is 2:2:2:

3.

5. The method for treating wastewater sludge according to claim 1, characterized in that: Part of the sludge in the sedimentation tank is discharged from the system through the sludge outlet, part of the sludge is returned to the first aerobic zone, and part of the sludge is returned to the side stream enhanced fermentation zone.

6. A wastewater sludge treatment system for the wastewater sludge treatment method according to any one of claims 1 to 5, characterized in that: include: The inlet water tank, the ozone oxidation zone, the first aerobic zone, the first anoxic zone, the second aerobic zone, the second anoxic zone, and the sedimentation tank are connected in sequence; and a side-stream enhanced fermentation area; A mud outlet of the sedimentation tank is connected to the side stream enhanced fermentation zone, mud outlets of the first aerobic zone and the second aerobic zone are connected to the side stream enhanced fermentation zone, and an outlet of the side stream enhanced fermentation zone is connected to the first anoxic zone and the second anoxic zone.

7. The wastewater sludge treatment system according to claim 6, characterized in that: It also includes an ozone generator connected to the ozone oxidation zone for providing ozone to the ozone oxidation zone; and an aeration head arranged in the first aerobic zone and the second aerobic zone, the aeration head being connected to an air pump.

8. The wastewater sludge treatment system according to claim 6, characterized in that: Also included is a stirring device for stirring the first anoxic zone and the second anoxic zone.

9. The wastewater sludge treatment system according to claim 6, characterized in that: It also includes a wave maker arranged in the side flow enhanced fermentation area.

10. The wastewater sludge treatment system according to claim 6, characterized in that: The water inlet tank, the ozone oxidation zone, the first aerobic zone, the first anoxic zone, the second aerobic zone, the second anoxic zone, the sedimentation tank, and the side stream enhanced fermentation zone are connected by pipelines, and water pumps or mud pumps are arranged on the pipelines.

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