Enhanced biological phosphorus removal device and method for side-flow mixed liquid suspended solid fermentation

Abstract

The invention discloses an enhanced biological phosphorus removal device for side-flow mixed liquid suspended solid fermentation, which comprises an urban sewage tank, a main flow reaction area and a secondary sedimentation tank, the urban sewage tank is communicated with an anaerobic tank through a water inlet peristaltic pump, the bottom outlet of the anaerobic tank is communicated with a side-flow anaerobic fermentation tank through an anaerobic tank sludge pump, and the main flow reaction area is communicated with the secondary sedimentation tank. The side flow anaerobic fermentation tank is connected into the anoxic tank I through a fermentation tank water outlet pump, the anoxic tank I, the aerobic tank I, the anoxic tank II and the aerobic tank II are sequentially communicated, the aerobic tank II is connected into the secondary sedimentation tank, a bottom outlet of the secondary sedimentation tank is connected into the pre-anoxic tank through a secondary sedimentation tank return sludge pump, and the secondary sedimentation tank outputs cleaned liquid through a secondary sedimentation tank water outlet pipe; and the aerobic tank I is connected back to the anoxic tank I through a nitrification liquid reflux pump. The invention further discloses an enhanced biological phosphorus removal method for lateral flow mixed liquid suspended solid fermentation. The invention belongs to the technical field of biological sewage treatment, and solves the problem that the traditional return sludge fermentation process needs longer SRT to realize sludge fermentation acid production.

Description

Technical Field

[0001] The invention belongs to the technical field of sewage biological treatment, and relates to an enhanced biological phosphorus removal device for suspended solid fermentation of a side stream mixed liquor. The invention also relates to an enhanced biological phosphorus removal method for suspended solid fermentation of a side stream mixed liquor. Background Art

[0002] The discharge of nitrogen and phosphorus nutrients is the main cause of eutrophication of receiving water bodies. At present, the methods for removing phosphorus from wastewater are mainly divided into chemical methods and biological methods. The chemical method mainly involves adding some chemical agents to the wastewater, such as iron salts, calcium salts, and aluminum salts, to react with phosphorus in the wastewater to form insoluble phosphate precipitates, and then remove phosphorus by solid-liquid separation. The biological enhanced phosphorus removal process (EBPR) is to remove phosphorus from wastewater by utilizing the characteristics of anaerobic phosphorus release and aerobic excess phosphorus absorption of activated sludge under the conditions of anaerobic and aerobic alternating operation, and remove phosphorus by discharging phosphorus-containing residual sludge. Compared with chemical methods, biological methods have the advantages of being environmentally friendly, low economic cost, and small carbon footprint. However, in the implementation of the EBPR process in specific sewage treatment plants, the growth and activity of polyphosphate bacteria are often inhibited due to the lack of carbon sources in the influent and the fluctuation of water quality, thus failing to meet the requirements of continuous and effective phosphorus removal performance, which has also forced some sewage treatment plants to rely more and more on chemical phosphorus removal methods. Although the chemical method is simple and efficient, it uses a large amount of chemicals, has high treatment costs, and produces a large amount of chemical sludge, which can easily cause secondary pollution if not properly handled. In addition, the chemical addition method also reduces the recovery efficiency of phosphorus in struvite. Summary of the invention

[0003] The purpose of the present invention is to provide an enhanced biological phosphorus removal device for suspended solid fermentation of side stream mixed liquor, which separates the hydraulic retention time (HRT) from the sludge retention time (SRT) to promote sludge hydrolysis and fermentation to produce volatile fatty acids (VFA) and supplement the carbon source of the influent, thereby solving the problem that the traditional reflow sludge fermentation process requires a longer SRT to achieve sludge fermentation and acid production. Another object of the present invention is to provide an enhanced biological phosphorus removal method by suspended solid fermentation of side stream mixed liquor, which solves the problems in the prior art that the activity of polyphosphate bacteria is inhibited due to low carbon source influent and fluctuation of influent water quality, resulting in poor phosphorus removal effect, and the use of chemical phosphorus removal causes increased operating costs.

[0004] The technical scheme adopted by the present invention is an enhanced biological phosphorus removal device for suspended solid fermentation of side stream mixed liquor, comprising a municipal sewage tank, a mainstream reaction zone and a secondary sedimentation tank, the municipal sewage tank is connected with an anaerobic tank through an inlet peristaltic pump, the bottom outlet of the anaerobic tank is connected with a side stream anaerobic fermentation tank through an anaerobic tank sludge pump, the side stream anaerobic fermentation tank is connected with anoxic tank one through a fermentation tank outlet pump, the anoxic tank one, aerobic tank one, anoxic tank two and aerobic tank two are connected in sequence, the aerobic tank two is connected with a secondary sedimentation tank, the bottom outlet of the secondary sedimentation tank is connected with a pre-anoxic tank through a secondary sedimentation tank return sludge pump, the secondary sedimentation tank outputs cleaned liquid through a secondary sedimentation tank drain pipe, and the aerobic tank one is connected back to the anoxic tank one through a nitrification liquid return pump.

[0005] Another technical solution adopted by the present invention is a method for enhancing biological phosphorus removal by suspended solid fermentation of a side stream mixed liquor, which is implemented by using the above-mentioned enhanced biological phosphorus removal device by suspended solid fermentation of a side stream mixed liquor according to the following steps: 1) Urban sewage from the urban sewage tank flows into the anaerobic tank; 2) The mud-water mixture in the anaerobic tank flows into the side-stream anaerobic fermentation tank for intermittent mixing; 3) The muddy water mixture of the anaerobic tank and the muddy water of the side-flow anaerobic fermentation tank flow into the anoxic tank 1, and the nitrification liquid flows back; 4) The mud-water mixture in the anoxic pool 1 flows into the aerobic pool 1, and the nitrification liquid flows back; 5) The mud-water mixture from aerobic pool 1 enters anoxic pool 2; 6) The mud-water mixture in the anoxic pool 2 flows into the aerobic pool 2; 7) The mud-water mixture from the aerobic tank II enters the secondary sedimentation tank for mud-water separation; 8) The supernatant and precipitated activated sludge in the secondary sedimentation tank are discharged separately; 9) The return sludge from the secondary sedimentation tank returns to the pre-anoxic tank for anaerobic fermentation and polyphosphate bacteria screening, and then returns to the anaerobic tank.

[0006] The beneficial effect of the present invention is that the enhanced biological phosphorus removal process based on the fermentation of suspended solids in the side stream mixed liquor does not use the traditional return sludge fermentation process, but introduces a part of the mixed liquor flowing out of the mainstream anaerobic tank into a specially set side stream reactor, and then uses intermittent stirring to make the mixed liquor suspended solids (MLSS) settle to form a sludge layer, so as to achieve the separation of hydraulic retention time (HRT) and sludge retention time (SRT), and then promote the hydrolysis and fermentation of sludge to produce volatile fatty acids VFA, supplement the carbon source of the influent, and provide for the use of polyphosphate bacteria and denitrifying bacteria in the anaerobic zone / anoxic zone to complete the denitrification and phosphorus removal. The process can produce VFA to the maximum extent and reduce the generation of methane and the release of nutrients, and can effectively remove nitrogen and phosphorus in urban sewage, providing a new process solution for urban sewage treatment.

[0007] (1) The setting of the side-stream anaerobic fermentation tank and the separation of mud and water through intermittent stirring, and the longer SRT make the sludge sedimentation area reach deep anaerobic conditions, which is conducive to the sludge fermentation acid production and the screening and strengthening of polyphosphate bacteria, creating powerful conditions for polyphosphate bacteria to gain an advantage in the competition with polysaccharide-accumulating bacteria, thereby enhancing the phosphorus removal performance of the process.

[0008] (2) The deep anaerobic fermentation of sludge in the side-stream anaerobic tank to produce acid can supplement the carbon source of the influent, increase the carbon-phosphorus ratio of the influent, and improve the phosphorus removal performance of the process.

[0009] (3) Since a certain amount of primary sludge fermentation supernatant is added to the sidestream pre-anoxic tank, the demand for fermentation acid production of return sludge is reduced, and the requirement for the retention time of return sludge in the sidestream process is shortened, thereby reducing the design size and floor space of the sidestream reactor, and allowing more return sludge to be supplemented with carbon sources and screened and domesticated through the sidestream reactor before returning to the mainstream process; (4) The influent carbon source is mainly supplied to the mainstream process for denitrification. At the same time, the supplement of primary sludge fermentation liquid and the acid production of return sludge fermentation also promote denitrification, thereby enhancing the nitrogen and phosphorus removal performance and stability of the overall process; (5) The fermentation return sludge in the side-stream anaerobic fermentation tank has a certain sludge reduction effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 It is a schematic structural diagram of the device of the present invention.

[0011] In the figure, 1. Urban sewage tank; 2. Inlet peristaltic pump; 3. Pre-anoxic tank; 3.1. Agitator 1; 4. Anaerobic tank; 4.1. Agitator 2; 5. Anaerobic tank sludge pump; 6. Side stream anaerobic fermentation tank; 6.1. Agitator 3; 7. Fermentation tank outlet pump; 8. Anoxic tank 1; 8.1. Agitator inlet peristaltic pump 4; 9. Aerobic tank 1; 9.1. Agitator 5; 10. Nitration liquid reflux pump; 11. Anoxic tank 2; 11.1. Agitator 6; 12. Aerobic tank 2; 12.1. Agitator 7; 13. Secondary sedimentation tank; 14. Secondary sedimentation tank drain pipe; 15. Secondary sedimentation tank return sludge pump. DETAILED DESCRIPTION

[0012] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0013] Reference Figure 1The structure of the enhanced biological phosphorus removal device for suspended solid fermentation of side stream mixed liquor of the present invention is as follows: the device comprises a municipal sewage tank 1, a mainstream reaction zone and a secondary sedimentation tank 13; the mainstream reaction zone is provided with a pre-anoxic tank 3, an anaerobic tank 4, an anoxic tank 1 8, an aerobic tank 1 9, an anoxic tank 2 11, and an aerobic tank 2 12 in parallel; the outlet of the municipal sewage tank 1 is connected to the anaerobic tank 4 through a water inlet peristaltic pump 2; the bottom outlet of the anaerobic tank 4 is connected to the side stream anaerobic fermentation tank 6 through an anaerobic tank sludge pump 5; the side stream anaerobic The outlet of the aerobic fermentation tank 6 is connected to the anoxic tank 1 8 through the fermentation tank outlet pump 7, and the anoxic tank 1 8, the aerobic tank 1 9, the anoxic tank 2 11, and the aerobic tank 2 12 are connected in sequence. The outlet of the aerobic tank 2 12 is connected to the secondary sedimentation tank 13, and the bottom outlet of the secondary sedimentation tank 13 is connected to the pre-anoxic tank 3 through the secondary sedimentation tank return sludge pump 15. The upper outlet of the secondary sedimentation tank 13 outputs the cleaned liquid through the secondary sedimentation tank drain pipe 14; the aerobic tank 1 9 is connected back to the anoxic tank 1 8 through the nitrification liquid return pump 10; The above-mentioned pre-anoxic tank 3 is equipped with a stirrer 3.1, the anaerobic tank 4 is equipped with a stirrer 4.1, the side-stream anaerobic fermentation tank 6 is equipped with a stirrer 3.1, the anoxic tank 8 is equipped with a stirrer 4.1, the aerobic tank 9 is equipped with a stirrer 5.1, the anoxic tank 2 11 is equipped with a stirrer 6.1, and the aerobic tank 2 12 is equipped with a stirrer 7.1; the anoxic tank 8 is equipped with a nitrification liquid delivery device; the aerobic tank 9 and the aerobic tank 2 12 are both equipped with aeration equipment; All five pumps (inlet peristaltic pump 2, anaerobic tank sludge pump 5, fermentation tank effluent pump 7, secondary sedimentation tank return sludge pump 15, nitrification liquid return pump 10) and seven agitators (agitator 1 3.1, agitator 2 4.1, agitator 3 6.1, agitator 4 8.1, agitator 5 9.1, agitator 6 11.1, agitator 7 12.1) are respectively connected to the main controller to achieve coordinated control or individual control.

[0014] The working principle of the device of the present invention is that the sewage from the urban sewage tank 1 is introduced into the anaerobic tank 4 through the water inlet peristaltic pump 2, a part of the muddy water mixed liquid in the anaerobic tank 4 is introduced into the side stream anaerobic fermentation tank 6 through the anaerobic tank sludge pump 5 for deep anaerobic fermentation, and then flows back to the anoxic tank 8 after passing through the fermentation tank outlet pump 7; the nitrification liquid is input into the anoxic tank 8, the mixed liquid in the anoxic tank 8 flows into the aerobic tank 9, and part of the nitrification liquid muddy water discharged from the aerobic tank 9 is returned to the anoxic tank 8 for reuse through the nitrification liquid reflux pump 10; another part of the nitrification liquid muddy water in the aerobic tank 9 is introduced into the second round The nitrified liquid mud water after the second round of the anoxic pool 11 and the aerobic pool 12 is introduced into the secondary sedimentation tank 13, and the secondary sedimentation tank 13 is provided with a secondary sedimentation tank drainage pipe 14 to output the upper clean liquid; after the nitrified liquid mud water in the secondary sedimentation tank 13 is separated by mud and water, the supernatant is directly discharged from the treatment system as effluent or discharged after deep treatment, and the sludge is divided into two parts, one part is discharged from the treatment system as residual sludge to achieve biological phosphorus removal, and the other part of the sludge is returned to the pre-anoxic pool 3 through the secondary sedimentation tank return sludge pump 15, and then flows into the anaerobic pool 4 through the pre-anoxic pool 3. Such a cycle realizes uninterrupted water purification.

[0015] The enhanced biological phosphorus removal method of the side stream mixed liquor suspended solid fermentation of the present invention is implemented by using the above-mentioned device according to the following steps: 1) The urban sewage in the urban sewage tank 1 flows into the anaerobic tank 4; 2) The mud-water mixture in the anaerobic tank 4 flows into the side-stream anaerobic fermentation tank 6, and is mixed intermittently in the side-stream anaerobic fermentation tank 6 for 1-5 minutes each time, twice a day; 3) The muddy water mixture discharged from the anaerobic tank 4 and the muddy water output from the side-stream anaerobic fermentation tank 6 flow into the anoxic tank 8, and the nitrification liquid is injected; 4) The muddy and water mixture discharged from the anoxic tank 8 flows into the aerobic tank 9, and the nitrification liquid flows back; 5) The muddy and water mixture discharged from the aerobic pool 19 enters the anoxic pool 211; 6) The muddy water mixture discharged from the anoxic pool 2 11 flows into the aerobic pool 2 12; 7) The muddy and water mixture discharged from the aerobic tank 2 12 enters the secondary sedimentation tank 13 for mud-water separation; 8) After the mud and water are separated in the secondary sedimentation tank 13, the supernatant is directly discharged from the system through the secondary sedimentation tank drain pipe 14, and the precipitated activated sludge is divided into two parts, one part is returned to the pre-anoxic tank 3 as return sludge, and the remaining part is directly discharged from the system; 9) The return sludge returns to the pre-anoxic tank 3 for anaerobic fermentation and polyphosphate bacteria screening, and then returns to the anaerobic tank 4 to repeat the cycle. All indicators of the final effluent meet the Class A emission standards specified in the "Standards for Pollutant Emissions from Urban Sewage Treatment Plants (GB18918-2002)"; at the same time, they meet the Class B emission standards specified in the "Standards for Pollutant Emissions from Urban Sewage Treatment Plants (GB18918-2002)".

[0016] During the above steps of the method of the present invention, the relevant process parameters are set as follows: 1) During the whole process, the sludge water temperature is 5℃~35℃, the pH is 6.5~8.0, and the sludge concentration is 2500~5000mg / L; 2) The dissolved oxygen (DO) concentration of the anaerobic tank 4 is 0.1-0.2 mg / L, the hydraulic retention time (HRT) is 0.9 h, and the mud-water ratio introduced into the side-stream anaerobic fermentation tank 6 is 5%-10%; 3) Intermittent stirring is implemented in the side stream anaerobic fermentation tank 6, twice a day, each time for 1 to 5 minutes, the HRT is 12 to 14 hours, the sludge retention time (SRT) is 46 to 48 hours, and the oxidation-reduction potential (ORP) is below -200 mV; 4) The dissolved oxygen (DO) concentration of the anoxic tank 8 is 0.2-0.6 mg / L, the nitrification solution reflux ratio is 100%-400%, and the HRT is 3.2h; 5) The dissolved oxygen (DO) concentration of aerobic pool 9 is not less than 2.0 mg / L, and the HRT is 12.5h; 6) The dissolved oxygen (DO) concentration of anoxic tank 21 is 0.2-0.6 mg / L, and the HRT is 1.65 h; 7) The dissolved oxygen (DO) concentration of aerobic pool 212 is not less than 2.0 mg / L, and the HRT is 0.5h; 8) The sludge return ratio of the secondary sedimentation tank 13 is 50% to 100%; 9) The dissolved oxygen (DO) concentration of the pre-anoxic tank 3 is 0.2-0.6 mg / L, and the HRT is 0.2 h.

[0017] The working principle of the method of the present invention is as follows: sewage from the urban sewage tank 1 flows into the anaerobic tank 4, and the mud and water are separated by stirring, and deep anaerobic conditions are achieved in the sludge sedimentation area, so that the sludge undergoes deep anaerobic fermentation to produce additional volatile fatty acids and enrich polyphosphate bacteria; part of the mud-water mixture in the anaerobic tank 4 flows to the side-stream anaerobic fermentation tank 6, and the sludge is hydrolyzed and fermented to produce acid, because its deep anaerobic environment can produce additional volatile fatty acids, and polyphosphate bacteria absorb volatile fatty acids and other available carbon sources, assimilate them into intracellular carbon energy storage materials polyhydroxyalkanoates (PHA), and store necessary carbon sources and energy for subsequent aerobic excess phosphorus absorption; part of the mixture flows to the anoxic tank 8, which provides a carbon source for denitrifying bacteria and removes nitrates refluxed from the aerobic tank 9. To achieve the purpose of denitrification; after the mud-water mixture in the anoxic tank 8 enters the aerobic tank 9, it relies on microorganisms to further decompose organic matter, polyphosphate bacteria absorb phosphorus, and phosphorus is transferred from the water phase to the mud phase. At the same time, ammonia nitrogen is converted into nitrate nitrogen under the action of nitrifying bacteria; part of the mud-water mixture in the aerobic tank 9 flows back to the anoxic tank 2 11 to improve the denitrification efficiency and remove residual organic matter; the mud-water mixture in the anoxic tank 2 11 flows to the aerobic tank 2 12 to further improve the nitrification efficiency and remove residual organic matter; after the mud-water mixture in the aerobic tank 2 12 flows into the secondary sedimentation tank 13, phosphorus is removed from the system through sedimentation and sludge discharge, thereby achieving the purpose of phosphorus removal; the return sludge flows through the pre-anoxic tank 3 to reduce the amount of nitrate entering the anaerobic tank 4 and reduce the impact of nitrate on anaerobic conditions. The final effluent water indicators are: COD = 48.3 mg / L, TN = 7.6 mg / L, all indicators meet the first-level A emission standards specified in the "Pollutant Emission Standards for Urban Sewage Treatment Plants (GB18918-2002)"; at the same time, TP = 1.5 mg / L, which meets the first-level B emission standards specified in the "Pollutant Emission Standards for Urban Sewage Treatment Plants (GB18918-2002)".

[0018] Example 1 Using the aforementioned device of the present invention, this embodiment 1 is implemented according to the following steps: 1) The urban sewage in the urban sewage tank 1 flows into the anaerobic tank 4, the COD in the sewage is 483 mg / L, TN is 48.2 mg / L, TP is 4.5 mg / L, the water temperature is 16.2℃, the HRT of the anaerobic tank 4 is 0.9h, and the sludge concentration is 3200 mg / L; 2) The muddy-water mixture in the anaerobic tank 4 flows into the side-stream anaerobic fermentation tank 6. The HRT of the side-stream anaerobic fermentation tank 6 is 13.6 h. Intermittent mixing is performed in the side-stream anaerobic fermentation tank 6 for 5 minutes, twice a day; 3) The muddy water mixture discharged from the anaerobic tank 4 and the muddy water output from the side-stream anaerobic fermentation tank 6 flow into the anoxic tank 8. The HRT in the anoxic tank 8 is 3.2h, the DO is 0.6 mg / L, and the nitrification solution is injected; 4) The muddy water mixture discharged from the anoxic tank 8 flows into the aerobic tank 9. The HRT in the aerobic tank 9 is 12.5h, the DO is greater than 2.0mg / L, and the nitrification liquid reflux ratio is 300%; 5) The muddy water mixture discharged from the aerobic pool 9 enters the anoxic pool 2 11. The HRT of the anoxic pool 2 11 is 1.65h and the DO is 0.6 mg / L; 6) The muddy water mixture discharged from the anoxic pool 2 11 flows into the aerobic pool 2 12. The HRT of the aerobic pool 2 12 is 0.5h, and the DO is greater than 2.0mg / L; 7) The sludge-water mixture discharged from the aerobic tank 2 12 enters the secondary sedimentation tank 13 for sludge-water separation. The sedimentation time of the secondary sedimentation tank 13 is 1.9 hours, and the sludge concentration is 8200 mg / L; 8) After the mud and water are separated in the secondary sedimentation tank 13, the supernatant is directly discharged from the system through the secondary sedimentation tank drain pipe 14, and the precipitated activated sludge is divided into two parts, one part is returned to the pre-anoxic tank 3 as return sludge, and the remaining part is directly discharged from the system, and the sludge return ratio is 60%; 9) The return sludge returns to the pre-anoxic tank 3 for re-anaerobic fermentation and polyphosphate bacteria screening, and then returns to the anaerobic tank 4. The HRT in the pre-anoxic tank 3 is 0.2h.

[0019] The final effluent water indicators are: COD = 48.3 mg / L, TN = 7.6 mg / L, all indicators meet the first-level A emission standards specified in the "Pollutant Emission Standards for Urban Sewage Treatment Plants (GB18918-2002)"; at the same time, TP = 1.5 mg / L, which meets the first-level B emission standards specified in the "Pollutant Emission Standards for Urban Sewage Treatment Plants (GB18918-2002)".

[0020] Example 2 Using the aforementioned device of the present invention, this embodiment 2 is implemented according to the following steps: 1) The urban sewage in the urban sewage tank 1 flows into the anaerobic tank 4, the COD in the sewage is 490 mg / L, TN is 49 mg / L, TP is 4.7 mg / L, the water temperature is 17°C, the HRT of the anaerobic tank 4 is 0.9h, and the sludge concentration is 3300 mg / L; 2) The muddy water mixture in the anaerobic tank 4 flows into the side-stream anaerobic fermentation tank 6. The HRT of the side-stream anaerobic fermentation tank 6 is 14h. Intermittent mixing is performed in the side-stream anaerobic fermentation tank 6 for 1 minute, twice a day; 3) The muddy water mixture discharged from the anaerobic tank 4 and the muddy water output from the side-stream anaerobic fermentation tank 6 flow into the anoxic tank 8. The HRT in the anoxic tank 8 is 3.2h, the DO is 0.5 mg / L, and the nitrification solution is injected; 4) The muddy water mixture discharged from the anoxic tank 8 flows into the aerobic tank 9. The HRT in the aerobic tank 9 is 12.5h, the DO is greater than 2.0mg / L, and the nitrification liquid reflux ratio is 350%; 5) The muddy water mixture discharged from the aerobic pool 9 enters the anoxic pool 2 11. The HRT of the anoxic pool 2 11 is 1.65h and the DO is 0.6 mg / L; 6) The muddy water mixture discharged from the anoxic pool 2 11 flows into the aerobic pool 2 12. The HRT of the aerobic pool 2 12 is 0.5h, and the DO is greater than 2.0mg / L; 7) The sludge-water mixture discharged from the aerobic tank 2 12 enters the secondary sedimentation tank 13 for sludge-water separation. The sedimentation time of the secondary sedimentation tank 13 is 2 hours, and the sludge concentration is 8300 mg / L; 8) After the mud and water are separated in the secondary sedimentation tank 13, the supernatant is directly discharged from the system through the secondary sedimentation tank drain pipe 14, and the precipitated activated sludge is divided into two parts, one part is returned to the pre-anoxic tank 3 as return sludge, and the remaining part is directly discharged from the system, and the sludge return ratio is 65%; 9) The return sludge returns to the pre-anoxic tank 3 for re-anaerobic fermentation and polyphosphate bacteria screening, and then returns to the anaerobic tank 4. The HRT in the pre-anoxic tank 3 is 0.2h.

[0021] The final effluent water indicators are: COD = 50 mg / L, TN = 8 mg / L, all indicators meet the first-level A emission standards specified in the "Pollutant Emission Standards for Urban Sewage Treatment Plants (GB18918-2002)"; at the same time, TP = 1.6 mg / L, which meets the first-level B emission standards specified in the "Pollutant Emission Standards for Urban Sewage Treatment Plants (GB18918-2002)".

[0022] Example 3 Using the aforementioned device of the present invention, this embodiment 3 is implemented according to the following steps: 1) The urban sewage in the urban sewage tank 1 flows into the anaerobic tank 4, the COD in the sewage is 475 mg / L, the TN is 47 mg / L, the TP is 4.3 mg / L, the water temperature is 15°C, the HRT of the anaerobic tank 4 is 13.5h, and the sludge concentration is 3100 mg / L; 2) The muddy-water mixture in the anaerobic tank 4 flows into the side-stream anaerobic fermentation tank 6. The HRT of the side-stream anaerobic fermentation tank 6 is 13.5 h. Intermittent mixing is performed in the side-stream anaerobic fermentation tank 6 for 2 minutes, twice a day; 3) The muddy water mixture discharged from the anaerobic tank 4 and the muddy water output from the side-stream anaerobic fermentation tank 6 flow into the anoxic tank 8. The HRT in the anoxic tank 8 is 3.2h, the DO is 0.6 mg / L, and the nitrification solution is injected; 4) The muddy water mixture discharged from the anoxic tank 8 flows into the aerobic tank 9. The HRT in the aerobic tank 9 is 12.5h, the DO is greater than 2.0mg / L, and the nitrification liquid reflux ratio is 320%; 5) The muddy water mixture discharged from the aerobic pool 9 enters the anoxic pool 2 11. The HRT of the anoxic pool 2 11 is 1.65h and the DO is 0.6 mg / L; 6) The muddy water mixture discharged from the anoxic pool 2 11 flows into the aerobic pool 2 12. The HRT of the aerobic pool 2 12 is 0.5h, and the DO is greater than 2.0mg / L; 7) The sludge-water mixture discharged from the aerobic tank 2 12 enters the secondary sedimentation tank 13 for sludge-water separation. The sedimentation time of the secondary sedimentation tank 13 is 1.8 hours, and the sludge concentration is 8100 mg / L; 8) After the mud and water are separated in the secondary sedimentation tank 13, the supernatant is directly discharged from the system through the secondary sedimentation tank drain pipe 14, and the precipitated activated sludge is divided into two parts, one part is returned to the pre-anoxic tank 3 as return sludge, and the remaining part is directly discharged from the system, and the sludge return ratio is 60%; 9) The return sludge returns to the pre-anoxic tank 3 for re-anaerobic fermentation and polyphosphate bacteria screening, and then returns to the anaerobic tank 4. The HRT in the pre-anoxic tank 3 is 0.2h.

[0023] The final effluent water indicators are: COD = 47 mg / L, TN = 7.5 mg / L, all indicators meet the first-level A emission standards specified in the "Pollutant Emission Standards for Urban Sewage Treatment Plants (GB18918-2002)"; at the same time, TP = 1.4 mg / L, which meets the first-level B emission standards specified in the "Pollutant Emission Standards for Urban Sewage Treatment Plants (GB18918-2002)".

[0024] Example 4 Using the aforementioned device of the present invention, this embodiment 4 is implemented according to the following steps: 1) The urban sewage in the urban sewage tank 1 flows into the anaerobic tank 4, the COD in the sewage is 480mg / L, TN is 48mg / L, TP is 4.6mg / L, the water temperature is 16.5℃, the HRT of the anaerobic tank 4 is 0.9h, and the sludge concentration is 3250mg / L; 2) The muddy-water mixture in the anaerobic tank 4 flows into the side-stream anaerobic fermentation tank 6. The HRT of the side-stream anaerobic fermentation tank 6 is 13.8 h. Intermittent mixing is performed in the side-stream anaerobic fermentation tank 6 for 3 minutes, twice a day; 3) The muddy water mixture discharged from the anaerobic tank 4 and the muddy water output from the side-stream anaerobic fermentation tank 6 flow into the anoxic tank 8. The HRT in the anoxic tank 8 is 3.2h, the DO is 0.6 mg / L, and the nitrification solution is injected; 4) The muddy water mixture discharged from the anoxic tank 8 flows into the aerobic tank 9. The HRT in the aerobic tank 9 is 12.5h, the DO is greater than 2.0mg / L, and the nitrification liquid reflux ratio is 330%; 5) The muddy water mixture discharged from the aerobic pool 9 enters the anoxic pool 2 11. The HRT of the anoxic pool 2 11 is 1.65h and the DO is 0.6 mg / L; 6) The muddy water mixture discharged from the anoxic pool 2 11 flows into the aerobic pool 2 12. The HRT of the aerobic pool 2 12 is 0.5h, and the DO is greater than 2.0mg / L; 7) The sludge-water mixture discharged from the aerobic tank 2 12 enters the secondary sedimentation tank 13 for sludge-water separation. The sedimentation time of the secondary sedimentation tank 13 is 1.9 hours, and the sludge concentration is 8250 mg / L; 8) After the mud and water are separated in the secondary sedimentation tank 13, the supernatant is directly discharged from the system through the secondary sedimentation tank drain pipe 14, and the precipitated activated sludge is divided into two parts, one part is returned to the pre-anoxic tank 3 as return sludge, and the remaining part is directly discharged from the system, and the sludge return ratio is 62%; 9) The return sludge returns to the pre-anoxic tank 3 for re-anaerobic fermentation and polyphosphate bacteria screening, and then returns to the anaerobic tank 4. The HRT in the pre-anoxic tank 3 is 0.2h.

[0025] The final effluent water indicators are: COD = 49 mg / L, TN = 7.7 mg / L, all indicators meet the first-level A emission standards specified in the "Pollutant Emission Standards for Urban Sewage Treatment Plants (GB18918-2002)"; at the same time, TP = 1.5 mg / L, which meets the first-level B emission standards specified in the "Pollutant Emission Standards for Urban Sewage Treatment Plants (GB18918-2002)".

[0026] Example 5 Using the aforementioned device of the present invention, this embodiment 5 is implemented according to the following steps: 1) The urban sewage in the urban sewage tank 1 flows into the anaerobic tank 4, the COD in the sewage is 485 mg / L, the TN is 48.5 mg / L, the TP is 4.4 mg / L, the water temperature is 16°C, the HRT of the anaerobic tank 4 is 0.9h, and the sludge concentration is 3200 mg / L; 2) The muddy-water mixture in the anaerobic tank 4 flows into the side-stream anaerobic fermentation tank 6. The HRT of the side-stream anaerobic fermentation tank 6 is 13.6 h. Intermittent mixing is performed in the side-stream anaerobic fermentation tank 6 for 4 minutes, twice a day; 3) The muddy water mixture discharged from the anaerobic tank 4 and the muddy water output from the side-stream anaerobic fermentation tank 6 flow into the anoxic tank 8. The HRT in the anoxic tank 8 is 3.2h, the DO is 0.6 mg / L, and the nitrification solution is injected; 4) The muddy water mixture discharged from the anoxic tank 8 flows into the aerobic tank 9. The HRT in the aerobic tank 9 is 12.5h, the DO is greater than 2.0mg / L, and the nitrification liquid reflux ratio is 300%; 5) The muddy water mixture discharged from the aerobic pool 9 enters the anoxic pool 2 11. The HRT of the anoxic pool 2 11 is 1.65h and the DO is 0.6 mg / L; 6) The muddy water mixture discharged from the anoxic pool 2 11 flows into the aerobic pool 2 12. The HRT of the aerobic pool 2 12 is 0.5h, and the DO is greater than 2.0mg / L; 7) The sludge-water mixture discharged from the aerobic tank 2 12 enters the secondary sedimentation tank 13 for sludge-water separation. The sedimentation time of the secondary sedimentation tank 13 is 1.9 hours, and the sludge concentration is 8200 mg / L; 8) After the mud and water are separated in the secondary sedimentation tank 13, the supernatant is directly discharged from the system through the secondary sedimentation tank drain pipe 14, and the precipitated activated sludge is divided into two parts, one part is returned to the pre-anoxic tank 3 as return sludge, and the remaining part is directly discharged from the system, and the sludge return ratio is 60%; 9) The return sludge returns to the pre-anoxic tank 3 for re-anaerobic fermentation and polyphosphate bacteria screening, and then returns to the anaerobic tank 4. The HRT in the pre-anoxic tank 3 is 0.2h.

[0027] The final effluent water indicators are: COD = 48 mg / L, TN = 7.6 mg / L, all indicators meet the first-level A emission standards specified in the "Pollutant Emission Standards for Urban Sewage Treatment Plants (GB18918-2002)"; at the same time, TP = 1.5 mg / L, which meets the first-level B emission standards specified in the "Pollutant Emission Standards for Urban Sewage Treatment Plants (GB18918-2002)".

[0028] Example 6 Using the aforementioned device of the present invention, this embodiment 6 is implemented according to the following steps: 1) The urban sewage in the urban sewage tank 1 flows into the anaerobic tank 4, the COD in the sewage is 478mg / L, TN is 47.8mg / L, TP is 4.6mg / L, the water temperature is 15.8℃, the HRT of the anaerobic tank 4 is 0.9h, and the sludge concentration is 3200mg / L; 2) The muddy-water mixture in the anaerobic tank 4 flows into the side-stream anaerobic fermentation tank 6. The HRT of the side-stream anaerobic fermentation tank 6 is 13.7 h. Intermittent mixing is performed in the side-stream anaerobic fermentation tank 6 for 5 minutes, twice a day; 3) The muddy water mixture discharged from the anaerobic tank 4 and the muddy water output from the side-stream anaerobic fermentation tank 6 flow into the anoxic tank 8. The HRT in the anoxic tank 8 is 3.2h, the DO is 0.6 mg / L, and the nitrification solution is injected; 4) The muddy water mixture discharged from the anoxic tank 8 flows into the aerobic tank 9. The HRT in the aerobic tank 9 is 12.5h, the DO is greater than 2.0mg / L, and the nitrification liquid reflux ratio is 310%; 5) The muddy water mixture discharged from the aerobic pool 9 enters the anoxic pool 2 11. The HRT of the anoxic pool 2 11 is 1.65h and the DO is 0.6 mg / L; 6) The muddy water mixture discharged from the anoxic pool 2 11 flows into the aerobic pool 2 12. The HRT of the aerobic pool 2 12 is 0.5h, and the DO is greater than 2.0mg / L; 7) The sludge-water mixture discharged from the aerobic tank 12 enters the secondary sedimentation tank 13 for sludge-water separation. The sedimentation time of the secondary sedimentation tank 13 is 1.9 hours, and the sludge concentration is 8150 mg / L; 8) After the mud and water are separated in the secondary sedimentation tank 13, the supernatant is directly discharged from the system through the secondary sedimentation tank drain pipe 14, and the precipitated activated sludge is divided into two parts, one part is returned to the pre-anoxic tank 3 as return sludge, and the remaining part is directly discharged from the system. The sludge return ratio is 61%; 9) The return sludge returns to the pre-anoxic tank 3 for re-anaerobic fermentation and polyphosphate bacteria screening, and then returns to the anaerobic tank 4. The HRT in the pre-anoxic tank 3 is 0.2h.

[0029] The final effluent water indicators are: COD = 47.8 mg / L, TN = 7.6 mg / L, all indicators meet the first-level A emission standards specified in the "Pollutant Emission Standards for Urban Sewage Treatment Plants (GB18918-2002)"; at the same time, TP = 1.4 mg / L, which meets the first-level B emission standards specified in the "Pollutant Emission Standards for Urban Sewage Treatment Plants (GB18918-2002)".

[0030] It can be seen that the enhanced biological phosphorus removal device and method of the side-stream mixed liquor suspended solid fermentation of the present invention is different from the existing side-stream sludge anaerobic fermentation process by passing part of the return sludge into the side-stream anaerobic tank for fermentation, but introduces a part of the mixed liquor flowing out of the mainstream anaerobic tank into a specially set side-stream anaerobic fermentation tank, and then uses intermittent stirring to settle the mixed liquor suspended solids (MLSS) to form a sludge layer, so as to achieve the separation of hydraulic retention time (HRT) and sludge retention time (SRT), thereby promoting sludge hydrolysis and fermentation to produce volatile fatty acids VFA, supplement the carbon source of the influent, and provide for the use of polyphosphate bacteria and denitrifying bacteria in the anaerobic zone / anoxic zone to complete the denitrification and phosphorus removal. Compared with traditional polyphosphate bacteria CandidatusAccumulibacter and denitrifying bacteria, it gets rid of or reduces the dependence on the carbon source of the influent to a certain extent, and improves the phosphorus removal effect and stability of the process. Due to the supplement of carbon source, the return sludge retention time of the side-stream process is greatly shortened, and the size and area of ​​the side-stream anaerobic tank are reduced.

Claims

1. An enhanced biological phosphorus removal device for suspended solid fermentation of side stream mixed liquor, characterized in that: The invention comprises a city sewage tank (1), a mainstream reaction zone and a secondary sedimentation tank (13). The city sewage tank (1) is connected to an anaerobic tank (4) through an inlet peristaltic pump (2). The bottom outlet of the anaerobic tank (4) is connected to a side stream anaerobic fermentation tank (6) through an anaerobic tank sludge pump (5). The side stream anaerobic fermentation tank (6) is connected to an anoxic tank 1 (8) through a fermentation tank outlet pump (7). The anoxic tank 1 (8), an aerobic tank 1 (9), anoxic tank 2 (11) and aerobic tank 2 (12) are connected in sequence. The aerobic tank 2 (12) is connected to a secondary sedimentation tank (13). The bottom outlet of the secondary sedimentation tank (13) is connected to a pre-anoxic tank (3) through a secondary sedimentation tank return sludge pump (15). The secondary sedimentation tank (13) outputs cleaned liquid through a secondary sedimentation tank drain pipe (14). The aerobic tank 1 (9) is connected back to the anoxic tank 1 (8) through a nitrification liquid return pump (10).

2. The enhanced biological phosphorus removal device for side stream mixed liquor suspended solid fermentation according to claim 1, characterized in that: The mainstream reaction zone is provided with a pre-anoxic tank (3), an anaerobic tank (4), anoxic tank one (8), aerobic tank one (9), anoxic tank two (11), and aerobic tank two (12) in parallel. The pre-anoxic tank (3) is equipped with a stirrer one (3.1), the anaerobic tank (4) is equipped with a stirrer two (4.1), the side-stream anaerobic fermentation tank (6) is equipped with a stirrer three (6.1), the anoxic tank one (8) is equipped with a stirrer four (8.1), the aerobic tank one (9) is equipped with a stirrer five (9.1), the anoxic tank two (11) is equipped with a stirrer six (11.1), and the aerobic tank two (12) is equipped with a stirrer seven (12.1).

3. The enhanced biological phosphorus removal device for side stream mixed liquor suspended solid fermentation according to claim 2, characterized in that: The stirrer 1 (3.1), stirrer 2 (4.1), stirrer 3 (6.1), stirrer 4 (8.1), stirrer 5 (9.1), stirrer 6 (11.1) and stirrer 7 (12.1) are respectively connected to the main controller.

4. The enhanced biological phosphorus removal device for side stream mixed liquor suspended solid fermentation according to claim 1, characterized in that: The anoxic pool 1 (8) is equipped with a nitrification liquid delivery device.

5. The enhanced biological phosphorus removal device for side stream mixed liquor suspended solid fermentation according to claim 1, characterized in that: The aerobic pool 1 (9) and the aerobic pool 2 (12) are both equipped with aeration equipment.

6. The enhanced biological phosphorus removal device for side stream mixed liquor suspended solid fermentation according to claim 1, characterized in that: The water inlet peristaltic pump (2), the anaerobic tank sludge pump (5), the fermentation tank effluent pump (7), the secondary sedimentation tank return sludge pump (15), and the nitrification liquid return pump (10) are respectively connected to the main controller.

7. A method for enhanced biological phosphorus removal by suspended solid fermentation of a side stream mixed liquor, using the device for enhanced biological phosphorus removal by suspended solid fermentation of a side stream mixed liquor according to any one of claims 1 to 6, characterized in that: Follow these steps to implement: 1) Urban sewage from the urban sewage tank (1) flows into the anaerobic tank (4); 2) The mud-water mixture in the anaerobic tank (4) flows into the side-stream anaerobic fermentation tank (6) for intermittent mixing; 3) The muddy water mixture from the anaerobic tank (4) and the muddy water from the side-stream anaerobic fermentation tank (6) flow into the anoxic tank 1 (8), and the nitrification liquid is injected; 4) The mud-water mixture from the anoxic pool 1 (8) flows into the aerobic pool 1 (9), and the nitrification liquid flows back; 5) The mud-water mixture from aerobic pool 1 (9) enters anoxic pool 2 (11); 6) The mud-water mixture from the anoxic pool 2 (11) flows into the aerobic pool 2 (12); 7) The mud-water mixture from the aerobic tank 2 (12) enters the secondary sedimentation tank (13) for mud-water separation; 8) The supernatant and the precipitated activated sludge in the secondary sedimentation tank (13) are discharged separately; 9) The return sludge from the secondary sedimentation tank (13) is returned to the pre-anoxic tank (3) for re-anaerobic fermentation and polyphosphate bacteria screening, and then returned to the anaerobic tank (4).

8. The enhanced biological phosphorus removal method of side stream mixed liquor suspended solid fermentation according to claim 7, characterized in that: During the entire process, the mud water temperature is 5-35°C, the pH is 6.5-8.0, and the sludge concentration is 2500-5000 mg / L.

9. The enhanced biological phosphorus removal method of side stream mixed liquor suspended solid fermentation according to claim 7, characterized in that: In step 2, the side stream fermenter is intermittently mixed for 1-5 minutes each time, twice a day.

10. The method for enhanced biological phosphorus removal by suspended solid fermentation of side stream mixed liquor according to claim 7, characterized in that: In step 8, the specific process is: The supernatant in the secondary sedimentation tank (13) is directly discharged from the system through the secondary sedimentation tank drain pipe (14); The settled activated sludge is divided into two parts, one part is returned to the pre-anoxic tank (3) as return sludge, and the rest is directly discharged from the system.

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