CN-116375288-B - High-efficiency nitrogen and phosphorus removal treatment method for domestic sewage with low carbon-nitrogen ratio

Abstract

The invention discloses a high-efficiency nitrogen and phosphorus removal treatment method for domestic sewage with a low carbon nitrogen ratio, which comprises the steps of increasing anoxic reaction time, setting two sections of anoxic reaction areas, simultaneously introducing double nitrification liquid for reflux, adjusting double nitrification liquid flow distribution according to a water inlet C/N ratio, strengthening denitrification and phosphorus removal technology, simultaneously combining a carbon source accurate adding system to ensure deep nitrogen and phosphorus removal of the whole process, on the other hand, setting an MBBR nitrification treatment unit, enabling suspended filler to provide good carriers for nitrifying bacteria, ensuring enrichment conditions of long sludge age of the nitrifying bacteria, and enabling the nitrifying liquid to reflux to an anoxic area for nitrogen removal.

Inventors

• ZHAO LI
• MIAO ZHIJIA
• FANG RUI
• YUN YUPAN
• SUN XUEYING
• ZHAO ZHIRUI
• An Heluan
• LI QING
• XUE SHIYU

Assignees

• 哈尔滨工业大学水资源国家工程研究中心有限公司
• 河北地质大学
• 广东粤海水务投资有限公司

Dates

Publication Date

20260512

Application Date

20230429

Claims (5)

1. 1. The high-efficiency nitrogen and phosphorus removal treatment method for the domestic sewage with the low carbon-nitrogen ratio is characterized by comprising the following steps of: Step 1, domestic sewage enters an anaerobic zone (3) of an A 2 /O system from a water tank (1) through a first water inlet pump (2), synchronously enters sludge pumped out from the bottom of the tail end of an aerobic II zone (7) through a first sludge reflux pump (17), has a sludge reflux ratio of 50% -200%, has a reflux sludge concentration of 4000-7000mg/L, and is stirred and mixed by an electric stirrer (29) to keep the HRT of the anaerobic zone (3) to be 2-3 hours; Step 2, the mixed solution enters an anoxic zone I (4), meanwhile, supernatant liquid obtained after solid-liquid separation of the mixed solution subjected to nitrification in a MBBR reaction zone (13) is fed into the anoxic zone I (4) through a first nitrifying liquid reflux pump (15), the HRT of the anoxic zone I (4) is 5-6 hours, and the nitrifying liquid reflux ratio is 100% -300%; Step 3, the mixed solution enters an aerobic zone I (5) through an anoxic zone I (4), dissolved oxygen is set to be 1-2.5 mg/L, and the HRT of the aerobic zone I (5) is set to be 1-2 h; Step 4, enabling the mixed solution to enter an anoxic zone II (6) through an aerobic zone I (5), enabling supernatant flowing out of a secondary sedimentation tank (14) to enter through a second nitrifying liquid reflux pump (16), enabling the nitrifying liquid reflux ratio to be 100% -200%, enabling the anoxic zone II (6) to be 3-4 h, arranging sodium acetate solution in an external carbon source storage tank (23), and adding the sodium acetate solution according to the TN removal amount/sodium acetate mass ratio of 1:4-1:6, wherein the external carbon source storage tank (23) is connected with the anoxic zone II (6) through a carbon source adding pump (24); Step 5, the mixed solution enters an aerobic zone II (7) through an anoxic zone II (6), the HRT of the aerobic zone II (7) is 2-3 hours, the dissolved oxygen is set to be 1.5-2.5 mg/L, mud-water separation is realized by an MBR membrane component (8), supernatant fluid enters an intermediate water tank (11) through a vacuum pump (10), and a second water inlet pump (12) injects sewage containing ammonia nitrogen into an MBBR reaction zone (13), and the sludge age is 8-12 d; Step 6, adding a suspension filler (30) into the MBBR reaction zone (13), wherein the specific surface area is 600-2000 m 2 /m 3 , the filling ratio is 30% -50%, the aeration amount is 3-6L/min, the dissolved oxygen concentration is 2-4 mg/L, the HRT is 3-4 h, the sludge concentration is 1500-3000 mg/L, the sludge age is 20-30 d, the biomass attached to carrier particles is 1.5-2.5 mg VSS/g dry particles, and the ammonia nitrogen removal rate is 0.7-2.2 kg N/(m 3 .d); step 7, the mixed solution enters a secondary sedimentation tank (14) through an MBBR reaction zone (13), sludge is precipitated and then flows back to the water inlet end of the MBBR reaction zone (13) from the lower end, a part of supernatant is discharged, and a part of supernatant flows back to an anoxic zone I (4) and an anoxic zone II (6); In the step 1, when the C/P ratio of the inlet water is 15:1-40:1, the sludge reflux ratio of the anaerobic zone (3) is 75-150%, and when the C/P ratio is 40:1-70:1, the sludge reflux ratio of the anaerobic zone (3) is 50-100%; In the step 2 and the step 4, when the ratio of the inflow water C/N is 3:1-5:1, the flow ratio of the inflow water C/N to the anoxic I area (4) and the anoxic II area (6) is 1:1-1:1.5, and when the ratio of the inflow water C/N is 5:1-8:1, the flow ratio of the inflow water C/N to the anoxic I area (4) and the anoxic II area (6) is 2:1-3:1; In the step 4, TN removal amount can be dynamically fed back by water quality indexes of water quality on-line monitoring equipment (31), and TN removal amount/sodium acetate mass ratio is 1:4-1:6; In the steps 1, 2, 3, 4, 5 and 6, the HRT of the anaerobic zone (3) is 2-3 hours, the HRT of the anoxic zone I (4) is 5-6 hours, the HRT of the aerobic zone I (5) is 1-2 hours, the HRT of the anoxic zone II (6) is 3-4 hours, the HRT of the aerobic zone II (7) is 2-3 hours, and the volume ratio of the improved A 2 /O anoxic zone is 55% -62%.
2. 2. The method for efficient nitrogen and phosphorus removal of low carbon-nitrogen ratio domestic sewage according to claim 1, wherein in the step 5, dissolved oxygen is set to be 1.5-2.5 mg/L, and sludge age is 8-12 d.
3. 3. The method for efficiently removing nitrogen and phosphorus from low carbon-nitrogen ratio domestic sewage according to claim 1, wherein in the step 6, the dissolved oxygen concentration of the MBBR reaction zone (13) is 2-4 mg/L, the HRT is 3-4 h, and the sludge age is 20-30 d.
4. 4. The method for efficient nitrogen and phosphorus removal treatment of low carbon nitrogen ratio domestic sewage according to claim 1, further comprising the steps of: The water tank (1) and the anoxic I zone (4) are provided with water quality on-line monitoring equipment (31), COD (chemical oxygen demand), ammonia nitrogen, total nitrogen and total phosphorus indexes can be fed back to a computer (27) in real time, the reflux ratio of nitrifying liquid can be adjusted according to the numerical value of the inflow water C/N, when the inflow water C/N ratio is 3:1-5:1, the reflux ratio of nitrifying liquid flowing back to the anoxic I zone (4) and the anoxic II zone (6) is 1:1-1:1.5, when the inflow water C/N ratio is 5:1-8:1, the reflux ratio of nitrifying liquid flowing back to the anoxic I zone (4) and the anoxic II zone (6) is 2:1-3:1, the reflux ratio of sludge in the anaerobic zone can be adjusted according to the numerical value of the inflow water C/P ratio, when the C/P ratio is 15:1-40:1, the reflux ratio of sludge in the anaerobic zone is 75% -150%, and when the C/P ratio is 40:1-70:1, the reflux ratio of sludge in the anaerobic zone is 50% -100%.
5. 5. The method for efficient nitrogen and phosphorus removal of low carbon-nitrogen ratio domestic sewage according to claim 1, wherein the method for efficient nitrogen and phosphorus removal of low carbon-nitrogen ratio domestic sewage uses the following device: The high-efficiency nitrogen and phosphorus removal treatment device for the domestic sewage with the low carbon-nitrogen ratio comprises a water tank (1), a first water inlet pump (2), an anaerobic zone (3), an anoxic zone I (4), an aerobic zone I (5), an anoxic zone II (6), an aerobic zone II (7), an MBR (membrane bioreactor) membrane component (8), a pressure gauge (9), a vacuum pump (10), an intermediate water tank (11), a second water inlet pump (12), an MBBR (13), a secondary sedimentation tank (14), a first nitrifying liquid reflux pump (15), a second nitrifying liquid reflux pump (16), a first sludge reflux pump (17), a second sludge reflux pump (18), a blower (19), a gas flowmeter (20), a water tank and a water tank, Aeration pipe (21), aeration head (22), external carbon source storage tank (23), carbon source dosing pump (24), online DO monitoring probe (25), handheld dissolved oxygen meter (26), computer (27), PLC controller (28), electric stirrer (29), suspension filler (30) and online water quality monitoring equipment (31), wherein water tank (1) is connected with anaerobic zone (3) through first intake pump (2), anaerobic zone (3), anoxic zone (4), aerobic zone I (5), The anaerobic treatment device comprises an anoxic zone II (6) and an aerobic zone II (7), wherein the anoxic zone II (7) is sequentially connected with an anaerobic zone (3) through a first sludge reflux pump (17), an MBR membrane module (8) is arranged in the aerobic zone II (7), the MBR membrane module (8) is connected with an intermediate water tank (11) through a pressure gauge (9) and a vacuum pump (10), the intermediate water tank (11) is connected with an MBBR reaction zone (13) through a second water inlet pump (12), a suspension filler (30) is arranged in the MBBR reaction zone (13), the MBBR reaction zone (13) is connected with a secondary sedimentation tank (14), the upper end of the secondary sedimentation tank (14) is connected with the anoxic zone I (4) and the anoxic zone II (6) through a first nitrifying liquid reflux pump (15) and a second nitrifying liquid reflux pump (16), the lower end of the secondary sedimentation tank (14) is connected with the MBBR reaction zone (13) through a second sludge reflux pump (18), one end of the intermediate water tank (19) is connected with an MBBR reaction zone (13) through a second water inlet pump (12), one end of the intermediate water tank (19) is connected with an aeration pipe (21) through a gas flowmeter (21), and the other end of the intermediate water tank (19) is connected with an aeration pipe (22) in the aeration zone (13), and the aeration zone (22) is arranged at the bottom of the aeration zone (13 is arranged in the aeration zone (5), An online DO monitoring probe (25) is arranged in the aerobic II area (7) and the MBBR reaction area (13), the online DO monitoring probe (25) is connected with a handheld dissolved oxygen meter (26), real-time signals are fed back to a computer (27), two water quality online monitoring devices (31) are respectively connected with a water tank (1) and an anoxic II area (6) and are fed back to the computer (27), the computer (27) is connected with a PLC (programmable logic controller) 28) and can adjust the flow of a first nitrifying liquid reflux pump (15), the flow of a second nitrifying liquid reflux pump (16), the flow of a first sludge reflux pump (17), the flow of the carbon source adding pump (24) and the air flow of the air blower (19) are respectively provided with an electric stirrer (29) in the anaerobic zone (3), the anoxic zone I (4) and the anoxic zone II (6).

Description

High-efficiency nitrogen and phosphorus removal treatment method for domestic sewage with low carbon-nitrogen ratio Technical Field The invention relates to the field of urban sewage treatment and regeneration, in particular to a high-efficiency nitrogen and phosphorus removal treatment device and a treatment method for domestic sewage with a low carbon nitrogen ratio. Background Under the strategic background of ecological civilization construction, the sewage treatment level is more and more emphasized in China, the pollutant discharge limit value of the urban sewage treatment plant at present implements the first-level A discharge standard specified in GB8918-2002, wherein TN is required to be smaller than 15mg/L, TP is required to be smaller than 1mg/L or 0.5mg/L, and part of sewage treatment plants cannot be discharged stably and up to the standard under the current situation. Meanwhile, the method has the advantages that the method is not only economical, but also in market, new local standards are put out, the sewage discharge limit value is further raised to the surface water IV standard or even III standard, the key and difficult points are the removal of nitrogen and phosphorus, and the main difficulties encountered in practice are represented by the problems of insufficient carbon source of sewage carbon-nitrogen ratio, contradiction between sludge age of nitrifying bacteria and phosphorus accumulating bacteria, low capacity of phosphorus release and phosphorus absorption, excessive addition of external carbon source, the defects and drawbacks existing in the process, and the like, and the process is required to be improved. The denitrification dephosphorization technology can absorb small molecular organic matters in water under anaerobic conditions to synthesize Polyhydroxyalkanoate (PHA) as an internal carbon source and release phosphate, NO 2-、NO3－ is used for replacing O 2 as an electron acceptor under anoxic conditions, PHA is used as an electron donor to perform anoxic dephosphorization, and synchronous high-efficiency denitrification dephosphorization is realized by running under anaerobic/anoxic alternating conditions. The Moving Bed Biofilm Reactor (MBBR) is to add suspended filler in an aeration tank as a microorganism growth carrier so as to form an activated sludge-biofilm composite ecological system. The addition of the suspended filler can effectively cut bubbles in the water body, so that the area of a gas-liquid film is increased, and the aeration efficiency is improved. The MBBR process has the advantages of low fluidization energy consumption, large biomass, small occupied area, large design elasticity, strong impact load resistance and the like. Nitrifying bacteria are typical autotrophic bacteria, long generation period is required for long sludge age, short sludge age is required in the dephosphorization process, and the contradiction of sludge age is difficult to balance in the denitrification and dephosphorization process. In addition, the nitrification effect of the actual water plant in winter is weakened to different degrees, and the denitrification efficiency of the whole process is influenced to a certain extent. Therefore, the technical advantages of the MBBR process are combined, and the single nitration reaction unit is arranged, so that the nitration effect can be ensured. At present, A 2/O and oxidation ditch improvement multistage AO and MBBR are common sewage treatment processes, but engineering problems of high process operation energy consumption, large carbon source addition amount, high sludge yield and the like exist in actual operation, and the situation that a large amount of carbon sources are added to realize TN standard is more common due to insufficient carbon sources in raw water. Disclosure of Invention The invention aims to provide a high-efficiency nitrogen and phosphorus removal treatment device and method for domestic sewage with a low carbon-nitrogen ratio, so as to solve the problems in the prior art. In order to achieve the above purpose, the present invention provides the following technical solutions: the high-efficiency nitrogen and phosphorus removal treatment method for the domestic sewage with the low carbon-nitrogen ratio comprises the following steps of: Step 1, domestic sewage enters an anaerobic zone of an A 2/O system from a water tank through a first water inlet pump, synchronously enters sludge pumped out by a sludge reflux pump at the bottom of the tail end of an aerobic zone II, has a sludge reflux ratio of 50% -200% and a reflux sludge concentration of 4000-7000mg/L, is stirred and mixed by an electric stirrer to keep the HRT of the anaerobic zone to be 2-3 h, and denitrifying phosphorus accumulating bacteria synthesizes an internal carbon source PHA in the anaerobic zone to release phosphate; And 2, enabling the mixed solution to enter an anoxic zone I, enabling supernatant liquid obtained after solid-liquid separation of th