AAO oxidation ditch sewage treatment device based on anaerobic sidestream sludge reduction

Abstract

The utility model discloses an anaerobic sidestream sludge reduction-based AAO oxidation ditch sewage treatment device, which has a sludge source reduction function, adopts an anaerobic-anoxic-oxidation ditch for nitrogen and phosphorus removal, and consists of an anaerobic tank, an anoxic tank, an oxidation ditch, a sedimentation tank and an anaerobic sidestream reactor, the anoxic tank and the anaerobic tank share a partial wall body, the oxidation ditch and the anoxic tank share a partial wall body, and the sedimentation tank and the oxidation ditch are combined to form a concentric double-wall cylindrical tank body; a submerged water impeller and a microporous aeration device are arranged in the oxidation ditch; a sludge scraper is arranged in the sedimentation tank, part of sludge discharged from the sedimentation tank enters the anaerobic sidestream reactor, and a sludge outlet of the anaerobic sidestream reactor is communicated with the oxidation ditch; and a sludge return pipe is arranged from the sedimentation tank to the anaerobic tank. The AAO oxidation ditch sewage treatment device based on anaerobic sidestream sludge reduction is suitable for treatment of urban domestic sewage, civil engineering investment and land occupation can be reduced, the anaerobic sidestream reactor is used for sludge source reduction, and the sludge treatment and disposal cost is reduced.

Description

Technical Field

[0001] This utility model relates to the technical field of wastewater treatment, and in particular to an AAO oxidation ditch wastewater treatment device based on anaerobic side-flow sludge reduction. Background Technology

[0002] Wastewater treatment systems based on the activated sludge process generate a large amount of excess sludge. The treatment and disposal of this excess sludge incurs high costs, and improper treatment can even pose a threat to the ecological environment.

[0003] AAO (Anaerobic-Anoxic-Oxic) oxidation ditch is one of the dominant technologies in urban wastewater treatment plants in my country. This process simultaneously removes nitrogen and phosphorus under anaerobic, anoxic, and aerobic conditions, offering high operational reliability, treatment stability, and water purification capabilities. However, the high sludge production rate remains an unavoidable issue, and the cost of sludge treatment and disposal places a burden on operations. Corresponding subsequent sludge treatment and disposal methods, such as sludge dewatering, sludge incineration, and sanitary landfill, have drawbacks including high costs, high energy consumption, and environmental hazards.

[0004] Compared with subsequent sludge treatment, sludge source reduction technology has significant advantages. The ASSR process constructs a cycle of aerobic-sedimentation-anaerobic alternation, which causes some of the returned sludge to undergo sludge decay, energy uncoupling, and extracellular polymer dissociation under nutrient-poor anaerobic conditions. This drives the process microbial community to evolve into a community structure of chronically growing microorganisms, thereby achieving sludge source reduction. Utility Model Content

[0005] The purpose of this invention is to provide an AAO oxidation ditch wastewater treatment device based on anaerobic side-flow sludge reduction, which solves the problem of high sludge production rate while ensuring the system's ability to remove pollutants.

[0006] To solve the above-mentioned technical problems, this utility model provides an AAO oxidation ditch wastewater treatment device based on anaerobic side-flow sludge reduction, including an anaerobic tank, an anoxic tank, an oxidation ditch, a sedimentation tank, and an anaerobic side-flow reactor.

[0007] The anaerobic tank, the anoxic tank, the oxidation ditch, and the sedimentation tank are connected sequentially along the direction of sewage inflow. Part of the sludge discharged from the sedimentation tank enters the anaerobic side-flow reactor and then flows back to the oxidation ditch. The sedimentation tank is provided with a return pipeline connected to the sludge inlet of the anaerobic side-flow reactor, and the sludge outlet of the anaerobic side-flow reactor is connected to the oxidation ditch.

[0008] In one embodiment, the anaerobic tank, the anoxic tank, the oxidation ditch, and the sedimentation tank constitute a main pipeline system for removing pollutants;

[0009] The oxidation ditch, the sedimentation tank, and the anaerobic side-flow reactor constitute a bypass system for sludge source reduction.

[0010] In one embodiment, the main road system adopts a combined structure;

[0011] The anaerobic tank and the anoxic tank are rectangular pools that are joined together and separated by a wall; the oxidation ditch and the anoxic tank share a portion of the wall.

[0012] The sedimentation tank and the oxidation ditch together form a concentric double-walled cylindrical tank body, with the oxidation ditch on the outside and the sedimentation tank on the inside.

[0013] The oxidation ditch and the sedimentation tank share the same inner wall. The anaerobic side-flow reactor, as the main structure of the bypass system, is spatially separated from the main system.

[0014] In one embodiment, the oxidation ditch has a first submersible flow generator and a microporous aeration device; the sedimentation tank has a sludge scraper; and a sludge return pipeline and a sludge return pump set are provided between the sedimentation tank and the anaerobic tank.

[0015] In one embodiment, the bypass system has an inlet pump group and an outlet pump group, the inlet pump group being connected to an inlet pipe between the secondary sedimentation tank and the anaerobic side-flow reactor, and the outlet pump group being connected to an outlet pipe between the anaerobic side-flow reactor and the oxidation ditch.

[0016] In one embodiment, the amount of sludge discharged from the sedimentation tank to the anaerobic side-flow reactor daily accounts for 5-15% of the amount of sludge in the oxidation ditch, and the hydraulic retention time of the anaerobic side-flow reactor is 1-15 days, with a sludge retention time of 1-15 days.

[0017] In one embodiment, the anaerobic side-flow reactor has a second submerged flow mixer for stirring the lower mud-water mixture and the supernatant in the anaerobic side-flow reactor to form a mud-water mixture for sludge discharge, or for periodically stirring the lower mud-water mixture and the supernatant for homogenization.

[0018] The beneficial effects of this utility model are as follows:

[0019] The main system constructs the anaerobic tank, the anoxic tank, the oxidation ditch, and the sedimentation tank through a shared wall and concentric circular structure. Because some activated sludge sequentially connects the oxidation ditch, the sedimentation tank, and the anaerobic side-flow reactor along the flow direction to form a loop, a cyclical aerobic-sedimentation-anaerobic process is achieved. This results in the following beneficial effects.

[0020] (1) Since the main road system shares the wall, the civil engineering investment and land occupation are reduced, and the stress direction inside and outside the wall is balanced, which reduces the wall thickness and construction difficulty; the shared wall has perforations for flow, saving the construction and maintenance of connecting pipes.

[0021] (2) Due to the aerobic-sedimentation-anaerobic cycle process formed by the bypass system, some of the returned sludge undergoes sludge decay, energy decoupling, and extracellular polymer dissociation under nutrient-poor anaerobic conditions, which drives the process microbial community to evolve into a community structure of chronically growing microorganisms, resulting in a reduction effect of 20-30%.

[0022] (3) Since the AAO oxidation ditch process is coupled with the MOSA process, the process has high effluent stability, nitrogen and phosphorus removal capacity and sludge reduction effect. While ensuring that the effluent meets the standards, it can reduce the amount of sludge at the source and reduce the burden of subsequent sludge treatment and disposal.

[0023] This effectively solves the problems of large footprint and high sludge production associated with conventional AAO oxidation ditch processes. Attached Figure Description

[0024] To more clearly illustrate the technical solution of this utility model, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0025] Figure 1 This is a structural schematic diagram provided by an embodiment of the present utility model.

[0026] The attached figures are labeled as follows:

[0027] 10. Anaerobic tank; 11. Anoxic tank; 12. Oxidation ditch; 13. First submersible flow generator; 14. Microporous aeration device;

[0028] 20. Sedimentation tank; 21. Sludge scraper;

[0029] 30. Anaerobic side-flow reactor; 31. Sludge inlet pump set; 32. Sludge outlet pump set;

[0030] 40. Sludge external return pump set. Detailed Implementation

[0031] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention.

[0032] This invention provides an AAO oxidation ditch wastewater treatment device based on anaerobic side-flow sludge reduction, the implementation of which is as follows: Figure 1As shown, the system mainly includes an anaerobic tank 10, an anoxic tank 11, an oxidation ditch 12, a sedimentation tank 20, and an anaerobic side-flow reactor 30. The anaerobic tank 10, anoxic tank 11, oxidation ditch 12, and sedimentation tank 20 are connected sequentially along the wastewater flow direction, forming the main system for pollutant removal. A portion of the sludge is connected sequentially along the flow direction to the oxidation ditch 12, sedimentation tank 20, and anaerobic side-flow reactor 30, forming a bypass system for sludge source reduction.

[0033] The wastewater treatment device used in this embodiment of the invention has a combined structure for the main system. The anaerobic tank 10 and the anoxic tank 11 are combined into a rectangular tank separated by a wall. The oxidation ditch 12 shares a portion of the wall with the anoxic tank 11. The sedimentation tank 20 and the oxidation ditch 12 are combined to form a concentric double-walled cylindrical tank, with the oxidation ditch 12 on the outer side and the sedimentation tank 20 on the inner side. The oxidation ditch 12 and the sedimentation tank 20 share the inner wall. The anaerobic side-flow reactor 30, as the main structure of the bypass system, is separated from the main system. Part of the sludge discharged from the sedimentation tank 20 enters the anaerobic side-flow reactor 30 and then flows back to the oxidation ditch 12. The return pipe of the sedimentation tank 20 is connected to the sludge inlet of the anaerobic side-flow reactor 30, and the sludge outlet of the anaerobic side-flow reactor 30 is connected to the starting end of the oxidation ditch 12.

[0034] In application, raw wastewater and returned sludge first enter the anaerobic tank 10 of the main pipeline system. In this section, polyphosphate-accumulating bacteria, under anaerobic conditions, decompose the polyphosphates within their bodies into inorganic phosphorus, releasing it into the liquid phase, thus completing phosphorus release. Dissolved organic matter is hydrolyzed and acidified by microorganisms, reducing BOD. Simultaneously, some organic matter is ammonified. The wastewater treated in anaerobic tank 10, along with the nitrified liquid returned from oxidation ditch 12, enters the anoxic tank 11. The main function of this section is denitrification. Denitrifying bacteria utilize the organic matter in the wastewater as a carbon source for denitrification, reducing NO3-. - -N and NO2 - -N is reduced to N2 and released into the air, further reducing the BOD concentration. After treatment in the anoxic tank 11, the wastewater enters the oxidation ditch 12. In this section, nitrifying bacteria utilize dissolved oxygen provided by the microporous aeration device 14 for nitrification. Microporous aeration increases oxygen mass transfer efficiency, reducing NH4+ in the wastewater. + -N is converted to NO2 - -N and NO3 --N, organic matter is further degraded under aerobic conditions. In addition, polyphosphate-accumulating bacteria use molecular oxygen or combined oxygen as electron acceptors to oxidize stored substances and generate energy, excessively absorbing phosphate from wastewater. Sludge settled in sedimentation tank 20 is transported to the starting end of anaerobic tank 10 by sludge scraper 21 and external sludge return pump group 40. Under alternating anaerobic and aerobic conditions, phosphorus release and absorption are completed, and phosphorus-containing excess sludge is discharged, removing phosphorus from the system. The main pipeline system can simultaneously perform nitrogen and phosphorus removal, resulting in strong water purification capacity, high effluent stability, and ensuring that the effluent meets the Class A standard of the "Discharge Standard of Pollutants for Municipal Wastewater Treatment Plants" (GB18918-2002). Furthermore, the combined structure layout and construction reduce land occupation and construction investment.

[0035] In the bypass system, a portion of the sludge discharged daily from sedimentation tank 20 is pumped into anaerobic side-flow reactor 30 via sludge inlet pump 31 for reaction, and then returned to the starting end of oxidation ditch 12 via sludge outlet pump 32, forming a cyclical process of aerobic-sedimentation-anaerobic. The daily sludge exchange rate of anaerobic side-flow reactor 30, i.e., the proportion of the amount of oven-dry sludge discharged from sedimentation tank 20 to anaerobic side-flow reactor 30 daily to the amount of oven-dry sludge in oxidation ditch 12, is 5-15%. The sludge exchange frequency of anaerobic side-flow reactor 30 can be 1-4 times / day. The operation mode of anaerobic side-flow reactor 30 mainly includes sludge discharge, sludge inlet, periodic stirring, settling, and sludge discharge stirring. Anaerobic side-flow reactor 30 strictly adheres to the procedure of sludge discharge before sludge inlet, with the amount of sludge discharged each time equal to the amount of sludge inlet. Periodic stirring is used to stir the lower layer of sludge-water mixture and the supernatant for homogenization and to accelerate the contact between sludge and substrate; the periodic stirring time is 60 minutes. The mud-water mixing is used to mix the lower mud-water mixture with the supernatant to form a mud-water mixture for mud discharge. The mud-water mixing begins 30 minutes before mud discharge.

[0036] In the anaerobic side-flow reactor 30, the anaerobic conditions under oligotrophic conditions facilitate endogenous respiration of the activated sludge, leading to sludge decay—the loss of active microorganisms in the absence of substrate. Secondly, cell lysis in the anaerobic side-flow reactor 30 releases biodegradable low-molecular-weight compounds, which some bacteria can utilize for reproduction—a process known as cryptic growth. Therefore, a recurring cycle of cell lysis and cryptic growth exists in the anaerobic side-flow reactor 30, resulting in a net loss of endogenous respiration substrate and a reduction in biomass. Additionally, anaerobic conditions also promote the dissociation of extracellular polymers in the activated sludge. In the anaerobic side-flow reactor 30, bacteria are driven to maintain metabolism, and ATP production is low due to the lack of substrate and effective electron acceptors (e.g., oxygen). When the sludge is returned to the oxidation ditch 12, bacteria preferentially replenish their energy reserves rather than synthesize new cells, thereby triggering sludge reduction through energy uncoupling. After long-term operation, the anaerobic side-flow reactor 30 can act as a biological selector, driving the process microbial community to evolve into a community structure of chronically growing microorganisms (such as hydrolytic acidifying bacteria, denitrifying bacteria, etc.), thereby steadily reducing sludge production. The sludge reduction effect can reach 20-30%.

[0037] The above description is the preferred embodiment of this utility model. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of this utility model, and these improvements and modifications are also considered to be within the protection scope of this utility model.

Claims

1. A wastewater treatment device for anaerobic side-flow sludge reduction using an AAO oxidation ditch, characterized in that, This includes anaerobic tanks, anoxic tanks, oxidation ditches, sedimentation tanks, and anaerobic side-flow reactors; The anaerobic tank, the anoxic tank, the oxidation ditch, and the sedimentation tank are connected sequentially along the direction of sewage inflow. Part of the sludge discharged from the sedimentation tank enters the anaerobic side-flow reactor and then flows back to the oxidation ditch. The sedimentation tank is provided with a return pipeline connected to the sludge inlet of the anaerobic side-flow reactor, and the sludge outlet of the anaerobic side-flow reactor is connected to the oxidation ditch.

2. The wastewater treatment device according to claim 1, characterized in that, The anaerobic tank, the anoxic tank, the oxidation ditch, and the sedimentation tank constitute the main pipeline system for removing pollutants; The oxidation ditch, the sedimentation tank, and the anaerobic side-flow reactor constitute a bypass system for sludge source reduction.

3. The wastewater treatment device according to claim 2, characterized in that, The main road system adopts a combined structure; The anaerobic tank and the anoxic tank are rectangular pools that are joined together and separated by a wall; the oxidation ditch and the anoxic tank share a portion of the wall. The sedimentation tank and the oxidation ditch together form a concentric double-walled cylindrical tank body, with the oxidation ditch on the outside and the sedimentation tank on the inside. The oxidation ditch and the sedimentation tank share the same inner wall. The anaerobic side-flow reactor, as the main structure of the bypass system, is spatially separated from the main system.

4. The wastewater treatment device according to claim 1, characterized in that, The oxidation ditch is equipped with a first submersible flow generator and a microporous aeration device; the sedimentation tank is equipped with a sludge scraper; and a sludge return pipeline and a sludge return pump set are connected between the sedimentation tank and the anaerobic tank.

5. The wastewater treatment device according to claim 3, characterized in that, The bypass system has an inlet pump group and an outlet pump group. The inlet pump group is connected to an inlet pipe between the sedimentation tank and the anaerobic side-flow reactor, and the outlet pump group is connected to an outlet pipe between the anaerobic side-flow reactor and the oxidation ditch.

6. The wastewater treatment device according to claim 1, characterized in that, The amount of sludge discharged daily from the sedimentation tank to the anaerobic side-flow reactor accounts for 5-15% of the total sludge volume in the oxidation ditch. The hydraulic retention time of the anaerobic side-flow reactor is 1-15 days, and the sludge retention time is 1-15 days.

7. The wastewater treatment device according to claim 1, characterized in that, The anaerobic side-flow reactor has a second submerged flow mixer, which is used to stir the lower mud-water mixture and the supernatant in the anaerobic side-flow reactor to form a mud-water mixture for sludge discharge, or to periodically stir the lower mud-water mixture and the supernatant for homogenization.

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