Urban domestic wastewater treatment method based on anaerobic ammonia oxidation reaction coupled phycomycete symbiotic process

Abstract

The invention provides an urban domestic wastewater treatment method based on an anaerobic ammonia oxidation reaction coupled phycomycete symbiotic process, and relates to the technical field of wastewater treatment. The treatment method is carried out in a reactor provided with a plurality of biological ribbons, and the plurality of biological ribbons are vertically arranged along the water flow direction to form soft isolation in the reactor; the method comprises the following steps: inoculating activated sludge into the reactor, and adding chlorella into the reaction tank at the same time; simulated wastewater containing a carbon source and a nitrogen source is introduced into the reaction tank for culture of a microbial system containing anaerobic ammonia oxidizing bacteria, NH4Cl serves as the nitrogen source of the simulated wastewater, NaHCO3 serves as the inorganic carbon source of the simulated wastewater, and glucose serves as the organic carbon source of the simulated wastewater; the reactor is used for treating urban domestic wastewater. Oxygen generated by photosynthesis of chlorella is used for replacing aeration, so that energy consumption is reduced to the greatest extent, an external carbon source is not needed, and the denitrification cost and the carbon emission are reduced.

Description

Technical Field

[0001] The present application relates to the technical field of wastewater treatment, and in particular to a method for treating urban domestic wastewater based on an anaerobic ammonia oxidation reaction coupled with an algae-bacteria symbiotic process. Background Art

[0002] Biological denitrification is a process that converts organic nitrogen and ammonia nitrogen in sewage into nitrogen gas under the action of microorganisms. It is economical, effective, easy to operate, and has no secondary pollution. This process is mainly divided into three stages: ammoniation, nitrification, and denitrification.

[0003] Ammonification refers to the conversion of organic nitrogen in sewage into ammonia nitrogen (NH 3 -N). Nitrification refers to the conversion of ammonia nitrogen into nitrite nitrogen (NO 2 -N) and nitrate nitrogen (NO 3 -N). This process is divided into two stages: nitrification and nitrification, which are completed by nitrite bacteria and nitrifying bacteria. Denitrification refers to the process in which denitrifying bacteria use carbon sources as electron donors to reduce nitrate nitrogen and nitrite nitrogen to nitrogen gas (N 2 ), thereby achieving nitrogen removal.

[0004] Anaerobic ammonium oxidation (ANAOM) is a widely used process in recent years and has a good application prospect in the treatment of urban domestic sewage. Anaerobic ammonium oxidation (ANAOM) refers to the process in which anaerobic ammonium oxidizing bacteria (AnAOB) use CO 2 As an inorganic carbon source, NH 4 + NO is used as an electron donor 2 - Direct oxidation to N 2 , thus completing the denitrification process, the theoretical reaction equation is as follows: NH 4 + +1.32NO 2 - +0.066HCO 3 - +0.13H + →0.26NO 3 -+1.02N 2 +0.066CH 2 O 0.5 N 0.15 +2.03H 2 O.

[0005] From the above reaction equation, it can be seen that sufficient reaction substrate NH 4+ and NO 2 - , while in urban domestic sewage NH 4 + At higher concentrations, NO 2 - Almost zero. Therefore, a stable and sufficient NO 2 - The source has become a limiting bottleneck in the application of anaerobic ammonium oxidation technology in the treatment of urban domestic sewage, resulting in a low nitrogen removal rate in urban domestic wastewater treated by anaerobic ammonium oxidation technology. Summary of the invention

[0006] In order to improve the NO 2 - The low nitrogen content leads to a low nitrogen removal rate in urban domestic wastewater treated by anaerobic ammonium oxidation technology. The present application provides an urban domestic wastewater treatment method based on anaerobic ammonium oxidation reaction coupled with algae-bacteria symbiotic process.

[0007] The present application provides a method for treating urban domestic wastewater based on anaerobic ammonium oxidation reaction coupled with algae-bacteria symbiotic process, which adopts the following technical scheme: A method for treating urban domestic wastewater based on an anaerobic ammonium oxidation reaction coupled with an algae-bacteria symbiotic process, wherein the treatment method is carried out in a reactor provided with a plurality of biological streamers, wherein the plurality of biological streamers are arranged vertically along the water flow direction to form a soft isolation in the reactor; The method comprises the following steps: Step S1: inoculating activated sludge into the reactor and adding Chlorella into the reaction tank; Step S2: introducing simulated wastewater containing carbon source and nitrogen source into the reaction tank to culture the microbial system containing anaerobic ammonia oxidizing bacteria, wherein the simulated wastewater is NH 4 Cl as nitrogen source, NaHCO 3 as inorganic carbon source and glucose as organic carbon source; Step S3: using the reactor to treat urban domestic wastewater.

[0008] The present invention realizes low-energy and low-emission treatment of low C / N urban domestic sewage by introducing the anaerobic ammonium oxidation-algae-bacteria symbiosis system into the bio-ribbon reactor. The reactor selects the bio-ribbon as the load material, which is used to simulate aquatic plants and has a rich pore structure inside, providing about 180-200m for the growth and reproduction of algae and other microorganisms in the water. 2The biological attachment surface area provides a large number of attachment sites and strong growth conditions, thereby improving the sewage treatment effect; the biological streamers are made of fiber cloth strips, which fundamentally determines the excellent performance and quality of the ecological base, and the ecological base is cheap and easy to obtain, reducing the treatment cost.

[0009] In this application, Chlorella is used as photosynthetic bacteria. Chlorella not only uses the oxygen produced by photosynthesis to provide oxygen for heterotrophic bacteria, but also absorbs nutrients such as nitrogen and phosphorus in the wastewater and organic products of anaerobic ammonium oxidation reaction for its own growth and removal of ammonia nitrogen (NH 4 + -N), total nitrogen (TN), total phosphorus (TP) and chemical oxygen demand (COD) to improve its degradation capacity; in addition, Chlorella improved the settling performance of anaerobic ammonium oxidation sludge through mucus production, particle aggregation, surface charge, bioadhesion, pH adjustment, oxygen supply, organic matter degradation and microbial community structure.

[0010] Heterotrophic bacteria attached to the surface and inside of the bio-ribbon, such as nitrifying bacteria and denitrifying bacteria, further degrade organic matter and use the oxygen produced by photosynthesis of Chlorella to oxidize the remaining ammonia nitrogen. Under the anaerobic conditions inside the bio-ribbon, anaerobic ammonia-oxidizing bacteria convert ammonia nitrogen (NH 4 + -N) and nitrite nitrogen (NO 2 - -N) into nitrogen (N 2 ), thereby achieving efficient denitrification effect.

[0011] The present application utilizes oxygen generated by photosynthesis of Chlorella to replace aeration, thereby reducing energy consumption to the greatest extent, and does not require an external carbon source, thereby reducing denitrification costs and carbon emissions. Therefore, it shows sufficient superiority in treating low C / N urban domestic sewage. This method does not require COD removal pretreatment, thereby improving the overall denitrification effect of the system.

[0012] Optionally, the activated sludge concentration MLVSS (volatile suspended solids in sludge mixed liquor) is 4.0-4.4 g / L, the activated sludge concentration MLSS (mixed liquor suspended solids) is 9.9-10.2 g / L, the Chlorella concentration is 4.3-4.4 g / L, and the mass ratio of Chlorella to the activated sludge is 4.89-5.50:1.

[0013] Furthermore, the activated sludge concentration MLVSS is 4.2 g / L, and the addition ratio of the Chlorella to the activated sludge is 5:1.

[0014] The present application further defines the concentration and addition ratio of activated sludge and Chlorella, thereby helping to form a stable microbial community in the reactor, thereby more efficiently removing pollutants in wastewater.

[0015] Optionally, step S2 includes three stages, namely: Step S21: Controlling NH in simulated wastewater 4 + -N concentration is 50~100mg / L, HCO 3 - With NH 4 + The mass ratio of NO in the effluent is 1.0-1.5, and the sewage return ratio is 100%. 2 - / NH 4 + When it is 1, it is considered that partial nitrification has been successfully started and enters the next stage; Step S22: Keep the simulated water inlet in step S21, and add NaNO to the simulated wastewater. 2 , control the NH in simulated wastewater 4 + -N concentration is 120-150 mg / L, HCO 3 - With NH 4 + The mass ratio of -N is 1.0 to 1.5, and NO 2 - With NH 4 +-N ratio is 1 to 1.32, sewage return ratio is 100%, hydraulic retention time is 18h; Step S23: Keep the simulated influent of step S21, and add 120-150 mg / L of glucose to the simulated wastewater, keep the influent C / N at 1, and control the NH 4 + -N concentration is 120-140 mg / L, HCO 3 - With NH 4 + The mass ratio of -N is 1.0-1.5, the sewage return ratio is 100%, and the hydraulic retention time is 12h.

[0016] The purpose of step S21 in this application is to start the nitrification process, that is, to 4 + -N) is partially converted into nitrite (NO 2 - ), by controlling NH 4 + -N concentration and HCO3 - With NH 4 + -N ratio can optimize the growth environment of nitrite-oxidizing bacteria (AOB) and promote the nitrite process; moreover, this stage also plays a role in screening and domesticating microorganisms, allowing microorganisms that can adapt to low C / N environments and specific growth conditions to survive and reproduce, thereby gradually establishing a stable microbial community.

[0017] The purpose of step S22 of the present application is to cultivate and domesticate anaerobic ammonia-oxidizing bacteria (AnAOB) to increase its abundance. 2 , providing electron acceptors in the anaerobic ammonium oxidation process, accelerating the anaerobic ammonium oxidation reaction; and, by adding NaNO 2 , which can optimize the growth environment of anaerobic ammonia-oxidizing bacteria and make them more adaptable to the treatment conditions of low C / N wastewater.

[0018] The purpose of step S23 of the present application is to achieve simultaneous nitrification and denitrification. By adding glucose to the simulated wastewater, the organic carbon source in the actual wastewater can be simulated to provide sufficient carbon source for the denitrification process, and the C / N ratio in the wastewater can be adjusted to make it more suitable for the simultaneous nitrification and denitrification process.

[0019] Therefore, the present application helps microorganisms gradually adapt to treatment conditions through staged cultivation, thereby improving the removal rate of nitrogen and organic matter.

[0020] Optionally, in step S21, the dissolved oxygen concentration at each location along the water flow direction in the reactor remains consistent; in step S22 and step S23, the dissolved oxygen concentration along the water flow direction in the reactor shows a decreasing trend.

[0021] Optionally, the reactor is divided into a first reaction section, a second reaction section and a third reaction section in sequence along the water flow direction. In the step S21, the dissolved oxygen concentration in each reaction section in the reactor is maintained at 0.5-0.8 mg / L; In step S22, the dissolved oxygen concentration of the first reaction section is controlled at 0.75-0.85 mg / L, the dissolved oxygen concentration of the second reaction section is controlled at 0.55-0.65 mg / L, and the dissolved oxygen concentration of the third reaction section is controlled at 0.35-0.45 mg / L; In step S23, the dissolved oxygen concentration of the first reaction section is controlled at 0.55-0.65 mg / L, the dissolved oxygen concentration of the second reaction section is controlled at 0.35-0.45 mg / L, and the dissolved oxygen concentration of the third reaction section is controlled at 0.15-0.25 mg / L.

[0022] Furthermore, in step S21, the dissolved oxygen concentration of each reaction section in the reactor is maintained at 0.8 mg / L; in step S22, the dissolved oxygen concentration of the first reaction section is controlled at 0.8 mg / L, the dissolved oxygen concentration of the second reaction section is controlled at 0.6 mg / L, and the dissolved oxygen concentration of the third reaction section is controlled at 0.4 mg / L; In step S23, the dissolved oxygen concentration of the first reaction section is controlled at 0.6 mg / L, the dissolved oxygen concentration of the second reaction section is controlled at 0.4 mg / L, and the dissolved oxygen concentration of the third reaction section is controlled at 0.2 mg / L.

[0023] In step S21, the present application controls the concentration of each reaction section to be the same, which can ensure that the nitrifying bacteria maintain a high activity, thereby accelerating the oxidation process of ammonia nitrogen. Moreover, under an appropriate dissolved oxygen concentration, not only can the nitrification rate be optimized, but it will not inhibit the nitrifying bacteria and will not cause problems such as sludge bulking.

[0024] In the present application, in step S22, the dissolved oxygen concentration in the reactor is controlled to show a decreasing trend. The high concentration of dissolved oxygen in the first reaction section can provide the necessary oxygen for the subsequent anaerobic ammonium oxidation process, while avoiding direct inhibition of the anaerobic ammonium oxidizing bacteria; the dissolved oxygen concentration in the second reaction section is reduced to further reduce the interference of oxygen on the anaerobic ammonium oxidation process; the dissolved oxygen concentration in the third reaction section is further reduced to be closer to anaerobic conditions, thereby promoting the activity of anaerobic ammonium oxidizing bacteria.

[0025] In step S23, the present application controls the dissolved oxygen concentration in the reactor to present a decreasing trend. The high concentration of dissolved oxygen in the first reaction section can support the nitrification process while avoiding the inhibitory effect on the denitrification process. The dissolved oxygen concentration in the second reaction section is reduced to create more favorable conditions for the denitrification process. The dissolved oxygen concentration in the third reaction section is further reduced to be closer to anoxic conditions to promote the denitrification process.

[0026] Moreover, the overall dissolved oxygen concentration in the reactor in step S22 of the present application is higher than that in step S23. Since step S22 is mainly in the anaerobic ammonium oxidation stage, anaerobic ammonium oxidizing bacteria are the main microbial species, and they are highly sensitive to dissolved oxygen, so it is necessary to optimize their growth environment by controlling the dissolved oxygen concentration. Step S23 is in the synchronous digestion and denitrification stage. Since there are two microbial communities of nitrifying bacteria and denitrifying bacteria at the same time, it is necessary to balance the growth requirements of the two microorganisms by accurately controlling the dissolved oxygen concentration to achieve efficient simultaneous nitrification and denitrification process.

[0027] Optionally, in step S2, the simulated wastewater is subjected to a pH adjustment treatment before entering the reactor, and the adjusted pH value is adjusted to 7.2-8; In the step S3, the urban domestic wastewater is subjected to pH adjustment treatment before entering the reactor, and the adjusted pH value is 7.2-8.

[0028] In the present application, in step S2, the pH value of the simulated wastewater is adjusted to a range that is more suitable for the growth of anaerobic ammonia-oxidizing bacteria.

[0029] Optionally, a trace element stock solution is also added to the simulated wastewater, with 5-5.5 mL of the trace element stock solution being added to every 15 L of simulated wastewater.

[0030] Optionally, the trace element stock solution contains the following components at concentrations: 3515 mg / L FeCl 3 6H 2 O, 359 mg / L MnCl 2 ·4H 2 O, 75mg / L CuSO 4 ·5H 2 O, 300mg / L ZnSO 4 7H 2 O, 375mg / LCoCl 2 6H 2 O.

[0031] The present application can provide future elements required for microbial growth by adding a reserve solution containing trace elements into simulated wastewater, thereby improving the metabolic activity of the microorganisms.

[0032] Optionally, in step S3, a continuous water inlet mode is adopted, and the hydraulic retention time is adjusted by controlling the water inlet flow rate.

[0033] Optionally, in step S3, light is provided inside the reactor and the temperature inside the reactor is controlled to be maintained within the range of 28-32°C.

[0034] The present application promotes the photosynthesis of Chlorella and the growth of microorganisms by providing light inside the reactor and controlling the temperature inside the reactor to remain within a suitable range.

[0035] In summary, the present application includes at least one of the following beneficial effects: 1. This application introduces the anaerobic ammonium oxidation-algae-bacteria symbiosis system into the bio-ribbon reactor to achieve low-energy consumption and low-emission treatment of low C / N urban domestic sewage. The reactor selects bio-ribbons as the load material, which is used to simulate aquatic plants and has a rich pore structure inside, providing about 180-200m for the growth and reproduction of algae and other microorganisms in the water. 2The large biological attachment surface area provides a large number of attachment sites and strong growth conditions, thereby improving the sewage treatment effect.

[0036] 2. This application uses Chlorella as photosynthetic bacteria. Chlorella not only uses the oxygen produced by photosynthesis to provide oxygen for heterotrophic bacteria, but also absorbs nutrients such as nitrogen and phosphorus in the wastewater and organic products of anaerobic ammonium oxidation reaction for its own growth and removal of ammonia nitrogen (NH 4 + -N), total nitrogen (TN), total phosphorus (TP) and chemical oxygen demand (COD) to improve its degradation capacity; in addition, Chlorella improved the settling performance of anaerobic ammonium oxidation sludge through mucus production, particle aggregation, surface charge, bioadhesion, pH adjustment, oxygen supply, organic matter degradation and microbial community structure.

[0037] 3. The present invention further degrades organic matter by attaching heterotrophic bacteria such as nitrifying bacteria and denitrifying bacteria on the surface and inside of the bio-ribbon, and uses the oxygen produced by photosynthesis of Chlorella to oxidize the remaining ammonia nitrogen; under the anaerobic conditions inside the bio-ribbon, anaerobic ammonia-oxidizing bacteria convert ammonia nitrogen (NH 4 + -N) and nitrite nitrogen (NO 2 - -N) into nitrogen (N 2 ), thereby achieving efficient denitrification effect.

[0038] 4. The present application utilizes oxygen generated by photosynthesis of Chlorella to replace aeration, thereby reducing energy consumption to the greatest extent, and does not require an external carbon source, thereby reducing denitrification costs and carbon emissions. Therefore, it shows sufficient superiority in treating low C / N urban domestic sewage. This method does not require COD removal pretreatment, thereby improving the overall denitrification effect of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 This is a schematic diagram of the connection relationship of an algae-bacteria symbiotic synergistic denitrification device based on anaerobic ammonia oxidation according to an embodiment of the present application; Figure 2 yes Figure 1 The process flow diagram of the algae-bacteria symbiotic synergistic denitrification device based on anaerobic ammonia oxidation is shown; Figure 3 yes Figure 2 A physical picture of the reactor of the algae-bacteria symbiotic synergistic denitrification device based on anaerobic ammonium oxidation is shown; Figure 4 yes Figure 3 A physical picture of the bio-streamers in the reactor shown; Figure 5 It is a scanning electron microscope image of the activated sludge sampled after the operation of step S3 is stabilized.

[0040] In the figure: 1. Water distribution tank; 2. Equalization tank; 3. Reactor; 4. LED energy-saving light strip; 5. Dissolved oxygen detector; 6. Sedimentation tank; 7. Biological streamer; 8. Reflux pump; 9. Water inlet pump. DETAILED DESCRIPTION

[0041] In response to the technical problems raised by the background technology, the applicant discovered that the oxygen produced by photosynthesis of algae can promote the nitrification reaction, that is, converting ammonia nitrogen into NO 2 -, thus providing a stable and sufficient supply of NO for anaerobic ammonium-oxidizing bacteria 2 - However, the presence of oxygen is not conducive to the denitrification reaction. Therefore, the applicant uses biological ribbons as the loading material, which has a rich pore structure inside and can provide anaerobic conditions for the denitrification reaction, so that it does not affect the conversion of ammonia nitrogen to NO 2 - / NO 3 - conversion, nor does it affect NO 2 - / NO 3 -Conversion into nitrogen gas, thus achieving efficient denitrification of wastewater.

[0042] The technical solution of the present application will be described in detail below with reference to the accompanying drawings.

[0043] First, the reaction device used in this application is described in detail. Figure 1-4 The reaction device comprises a reaction tank (3), which is made of organic glass, has a length of 40 cm, a width and a height of 15 cm, a reactor volume of 9 L, an effective volume of 7.8 L, and a sealable upper cover to facilitate the collection of water samples in different reaction sections and the replacement of fillers.

[0044] Eight biological streamers are arranged in the reaction pool (3), thereby dividing the interior of the reaction pool into nine reaction spaces, and every three reaction spaces are set as a reaction section, and the direction from the water inlet to the water outlet is the first reaction section, the second reaction section and the third reaction section. The biological streamer is made of a fiber cloth strip with a length of 15 cm and a width of 13 cm, and is used to simulate aquatic plants in the water body and provide attachment points for microorganisms. The advantages are that algae and microorganisms are easier to attach, the biofilm is fast, the price is low, and the cost performance is outstanding.

[0045] The outer layer of the reaction tank is equipped with heating, insulation and lighting facilities (used to simulate sunlight) to ensure that algae and microorganisms grow under suitable conditions. At the same time, the outer layer of the reactor is wrapped with a heating soft plate to adjust the temperature inside the reactor to keep the temperature at 30±2℃. Because light has a certain inhibitory effect on anaerobic ammonia-oxidizing bacteria, the insulation layer can also play a shading role.

[0046] The reaction device also includes a regulating tank located at the front end of the reactor and a sedimentation tank located at the rear end of the reactor. The regulating tank is connected to the water inlet of the reactor through a water inlet pump, and the sedimentation tank is connected to the regulating tank through a reflux pump.

[0047] The activated sludge used in the following examples was taken from the secondary sedimentation tank of Xinglin Sewage Treatment Plant in Xiamen, China, and the MLVSS (volatile suspended solids of sludge mixed liquor) was 4.2 g / L; the Chlorella used in the following examples was purchased from Hainan Yuanquan Biotechnology Co., Ltd.; the biological streamers used in the following examples were made of polymer fibers, which had a suitable pore structure inside and a high biological attachment surface area, and were purchased from Xiangtan Yunfan New Materials Co., Ltd.

[0048] The simulated wastewater used in the following examples includes conventional nutrients in addition to water, wherein the conventional nutrients include carbon sources (glucose, sodium bicarbonate), nitrogen sources (ammonium chloride), etc., and the corresponding pollutants are chemical oxygen demand (COD) and N (NH 4 + -N, TN), etc. At the same time, in order to provide a good growth environment for microorganisms, a quantitative trace element solution needs to be added to the simulated wastewater, and 5.125mL of trace element stock solution is added to every 15L of simulated wastewater. The trace element stock solution contains the following components at the following concentrations: 3515mg / L FeCl 3 6H 2 O, 359 mg / L MnCl 2 ·4H 2 O, 75mg / LCuSO 4 ·5H 2 O, 300mg / LZnSO 4 7H 2 O, 375mg / L CoCl 2 6H 2 O.

[0049] An embodiment of the present application provides a method for treating urban domestic wastewater based on an anaerobic ammonium oxidation reaction coupled with an algae-bacteria symbiotic process, comprising the following steps: Step S1: inoculating activated sludge into the reactor, and adding Chlorella into the reaction tank at the same time, the mass ratio of Chlorella to activated sludge is 5:1; the effective volume of the reactor is 7.8L, the input amount of activated sludge is 7.8L, filling the effective volume of the reactor, the activated sludge concentration MLVSS is 4.2g / L, and the Chlorella concentration is 4.3-4.4g / L.

[0050] Step S2: The simulated wastewater is passed through a regulating tank to adjust the pH value to 7.2-8 and then introduced into a reaction tank to cultivate the microbial system, which is specifically divided into three stages, namely: Step S21, partial nitrite start-up acclimatization stage: simulated wastewater with NH 4 Cl as nitrogen source, NaHCO 3 As a carbon source, control NH4 in simulated wastewater + -N concentration is 50~100mg / L, HCO 3 - With NH4 + The mass ratio of -N is 1.0 to 1.5. Other components include components that provide alkalinity suitable for the growth of microorganisms, namely: KH 2 PO 4 2.7mg / L, MgSO 4 7H 2 O is 30mg / L, CaCl 2 is 13.6 mg / L; in this stage, the dissolved oxygen concentration in the reactor is controlled to be maintained at 0.5-0.8 mg / L, the hydraulic retention time is 24h, the sewage return ratio is 100%, and when NO 2 - / NH 4 + When it is approximately 1, it is considered that partial nitrification has been successfully started and enters the next stage; Step S22, acclimatization of anaerobic ammonium-oxidizing bacteria: maintain the simulated influent in step S21, control the NH4+-N concentration in the simulated wastewater to 120-150 mg / L, the mass ratio of HCO3- to NH4+-N to 1.0-1.5, and add NaNO 2 Provide NO2- so that the ratio of NO2- to NH4+-N is 1 to 1.32. The other components in the simulated wastewater are the same as those in the partial nitrite startup acclimation stage of the previous stage. In this stage, the dissolved oxygen concentration in the reactor is controlled to be a gradient decrease trend, the first reaction stage is controlled at 0.8 mg / L, the second reaction stage is controlled at 0.6 mg / L, and the third reaction stage is controlled at 0.4 mg / L. The hydraulic retention time is 18 hours, and the sewage return ratio is 100%; Step S23, synchronous nitrification and denitrification stage: maintaining the simulated influent in step S21, controlling the NH 4 + -N concentration is 120-140 mg / L, HCO 3 - With NH 4 +-N mass ratio is 1.0~1.5, nitrite in step S22 is cancelled, glucose is added to the simulated wastewater to provide COD, COD is 120-150mg / L, the influent C / N is kept at 1, and other components in the simulated wastewater are the same as the partial nitrite startup acclimation stage in the previous stage; in this stage, the dissolved oxygen concentration in the reactor is controlled to be a gradient decrease trend, the first reaction section is controlled at 0.6mg / L, the second reaction section is controlled at 0.4mg / L, the third reaction section is controlled at 0.2mg / L, the hydraulic retention time is 12h, and the sewage return ratio is 100%. In this stage, due to the presence of COD, the growth rate of denitrifying bacteria is higher than that of nitrite bacteria and anaerobic ammonia oxidizing bacteria, so there is no need to additionally inoculate denitrifying bacteria in the reactor.

[0051] Step S3: Use the reactor to treat urban domestic wastewater. The urban domestic wastewater to be treated enters the regulating tank through the water distribution tank and mixes with part of the returned wastewater. The pH value is adjusted to 7.2-8, and then enters the reactor. The eight biological streamers set up in the reactor divide the inside of the reactor into nine reaction sections. With the entry of the water flow, the water in one reaction section enters the next reaction section through overflow, without the need for an additional peristaltic pump. Finally, the treated sewage enters the sedimentation tank and part of it flows back to the regulating tank, and part of it is discharged after sedimentation. A sludge outlet is set at the bottom of the sedimentation tank, and part of the sludge flows back to the reactor to replenish the lost microbial concentration.

[0052] In the above step S3, the hydraulic retention time of each reaction section can be controlled by controlling the water inlet flow rate. Specifically, the water inlet flow rate is controlled to 10.83 mL / min, and the hydraulic retention time can be controlled to 12 h. Moreover, each reaction section can also control the growth position of Chlorella by the number of inoculated Chlorella and the light, and control the dissolved oxygen concentration in the reactor. Moreover, in step S3, the dissolved oxygen concentration of each reaction section in the reactor is consistent with the dissolved oxygen concentration in step S23, that is, the first reaction section is controlled at 0.6 mg / L, the second reaction section is controlled at 0.4 mg / L, and the third reaction section is controlled at 0.2 mg / L.

[0053] In the above step S3, there are three main types of microorganisms in the reactor, chlorella, anaerobic ammonia oxidizing bacteria and other bacteria (nitrite bacteria, denitrifying bacteria, etc.). Adequate lighting conditions are provided in the reactor to promote the photosynthesis of chlorella. Chlorella uses sunlight, water and carbon dioxide to produce organic matter through photosynthesis and releases oxygen. Other bacteria can just use the products produced by chlorella, while anaerobic ammonia oxidizing bacteria can use the metabolites of other microorganisms for metabolic activities, such as ammonia nitrogen, nitrite nitrogen, carbon dioxide, etc. At the same time, anaerobic ammonia oxidizing granular sludge can significantly improve the sedimentation performance of the algae-bacteria synergistic symbiotic system, change the community structure of activated sludge, and increase microbial abundance. In addition, the suspended growth of chlorella has a protective effect on the light damage of ammonia oxidizing bacteria (AOB) and nitrite oxidizing bacteria (NOB).

[0054] After step S3 runs stably, water samples are taken regularly for water quality testing to measure nitrogen concentration and COD in the water samples. Cr , the analysis methods of nitrogen content in water samples are: COD Cr GBT11914-1989 "Water Quality Chemical Oxygen Demand - Dichromate Method" was used for testing; HJ535-2009 "Water Quality - Ammonia Nitrogen - Nessler Reagent Spectrophotometric Method" was used for testing of ammonia nitrogen; HJ / T346-2007 "Water Quality - Nitrate Nitrogen - Ultraviolet Spectrophotometric Method" was used for testing of nitrate nitrogen; GB / T7493-1987 "Water Quality - Nitrite Nitrogen - Spectrophotometric Method" was used for testing of nitrite nitrogen; total nitrogen was calculated as the sum of ammonia nitrogen, nitrate nitrogen and nitrite nitrogen. The test results of water samples for 3 days are shown in Table 1.

[0055] Table 1 Water sample test results From the results in Table 1, it can be seen that the urban domestic wastewater treatment method of the present application can reduce the COD Cr The content is reduced from 124.2-172.8 mg / L to 16.27-21.84 mg / L, and the removal rate is at least 86.5%. The total nitrogen content in the sewage is reduced from 141.6-153.6 mg / L to 22.2-27.47 mg / L, and the removal rate is at least 80.6%.

[0056] Figure 5 This is a SEM image of the activated sludge sampled after the operation of step S3 stabilized. Figure 5 It can be seen that there are a large number of extracellular polymers (EPS) on the surface of Chlorella and activated sludge. The morphological characteristics of Chlorella are relatively smooth and plump, and there are no bacteria attached to the surface. The surface of anaerobic ammonium oxidation granular sludge has a multi-hollow structure, which can provide a large number of adsorption sites and anaerobic environment.

[0057] In addition, the microbial characteristics and metabolic functions in the system at different times were analyzed by metagenomic sequencing, and the results are shown as follows. In the initial sludge, the relative abundances were ranked from high to low as Proteobacteria, Actinobacteria, Chloroflexi, Acidobacteria, Bacteroidetes and Planctomycetes, with relative abundances of 32.48%, 18.17%, 13.28%, 9.02%, 8.61% and 5.6%, respectively. In the final stage of the process operation (i.e., the end of step S23), the top five phyla in relative abundance included Planctomycetes, Proteobacteria, Chloroflexi, Bacteroidetes and Actinobacteria, accounting for 33%, 12.3%, 10.1%, 9.8% and 4.9%, respectively. g__Candidatus_Brocadia, as a typical genus of anaerobic ammonia-oxidizing bacteria, had a relative abundance of 29.85%, making it the main contributor to nitrogen removal in the anaerobic ammonia-oxidation reaction.

[0058] The above results effectively demonstrate that the co-cultivation of Chlorella and activated sludge significantly changes the bacterial community structure, forms a specific community structure dominated by functional microorganisms, increases the abundance of microbial species, and effectively inhibits the occurrence of sludge bulking.

[0059] The above are all preferred embodiments of the present application, and the protection scope of the present application is not limited thereto. Therefore, any equivalent changes made according to the structure, shape, and principle of the present application should be included in the protection scope of the present application.

Claims

1. A method for treating urban domestic wastewater based on anaerobic ammonium oxidation reaction coupled with algae-bacteria symbiotic process, characterized in that: The treatment method is carried out in a reactor provided with a plurality of biological streamers, wherein the plurality of biological streamers are arranged vertically along the water flow direction to form a soft isolation in the reactor; The method comprises the following steps: Step S1: inoculating activated sludge into the reactor and adding Chlorella into the reaction tank; Step S2: introducing simulated wastewater containing a carbon source and a nitrogen source into the reaction tank to culture a microbial system containing anaerobic ammonia-oxidizing bacteria, wherein the simulated wastewater contains NH4Cl as a nitrogen source, NaHCO3 as an inorganic carbon source, and glucose as an organic carbon source; Step S3: using the reactor to treat urban domestic wastewater.

2. The method for treating urban domestic wastewater based on anaerobic ammonium oxidation reaction coupled with algae-bacteria symbiotic process according to claim 1, characterized in that: The activated sludge concentration MLVSS is 4.0-4.4 g / L, the Chlorella concentration is 4.3-4.4 g / L, and the mass ratio of the Chlorella to the activated sludge is 4.89-5.50:

1.

3. The method for treating urban domestic wastewater based on anaerobic ammonium oxidation reaction coupled with algae-bacteria symbiotic process according to claim 1, characterized in that: The step S2 includes three stages, namely: Step S21: Controlling NH4 in simulated wastewater + -N concentration is 50~100 mg / L, HCO3 - With NH4 + -N mass ratio is 1.0~1.5, sewage return ratio is 100%, when NO2 - / NH4 + When it is 1, it is considered that partial nitrification has been successfully started and enters the next stage; Step S22: Keep the simulated influent in step S21, and add NaNO2 to the simulated wastewater to control the NH4 + -N concentration is 120-150 mg / L, HCO3 - With NH4 + -N mass ratio is 1.0~1.5, and NO2 - The ratio to NH4+-N is 1-1.32, the sewage return ratio is 100%, and the hydraulic retention time is 18h; Step S23: Keep the simulated influent of step S21, and add 120-150 mg / L of glucose to the simulated wastewater, keep the influent C / N at 1, and control the NH4 + -N concentration is 120-140 mg / L, HCO3 - With NH4 + The mass ratio of -N is 1.0~1.5, the sewage return ratio is 100%, and the hydraulic retention time is 12h.

4. The method for treating urban domestic wastewater based on anaerobic ammonium oxidation reaction coupled with algae-bacteria symbiotic process according to claim 3 is characterized in that: In step S21, the dissolved oxygen concentration at each location along the water flow direction in the reactor remains consistent; in steps S22 and S23, the dissolved oxygen concentration along the water flow direction in the reactor shows a decreasing trend.

5. The method for treating urban domestic wastewater based on anaerobic ammonium oxidation reaction coupled with algae-bacteria symbiotic process according to claim 4, characterized in that: The reactor is divided into a first reaction section, a second reaction section and a third reaction section in sequence along the water flow direction. In the step S21, the dissolved oxygen concentration in each reaction section in the reactor is maintained at 0.5-0.8 mg / L; In step S22, the dissolved oxygen concentration of the first reaction section is controlled at 0.75-0.85 mg / L, the dissolved oxygen concentration of the second reaction section is controlled at 0.55-0.65 mg / L, and the dissolved oxygen concentration of the third reaction section is controlled at 0.35-0.45 mg / L; In step S23, the dissolved oxygen concentration of the first reaction section is controlled at 0.55-0.65 mg / L, the dissolved oxygen concentration of the second reaction section is controlled at 0.35-0.45 mg / L, and the dissolved oxygen concentration of the third reaction section is controlled at 0.15-0.25 mg / L.

6. The method for treating urban domestic wastewater based on anaerobic ammonium oxidation reaction coupled with algae-bacteria symbiotic process according to claim 1, characterized in that: In the step S2, the simulated wastewater is subjected to a pH adjustment treatment before entering the reactor, and the adjusted pH value is adjusted to 7.2-8; In the step S3, the urban domestic wastewater is subjected to pH adjustment treatment before entering the reactor, and the adjusted pH value is 7.2-8.

7. The method for treating urban domestic wastewater based on anaerobic ammonium oxidation reaction coupled with algae-bacteria symbiotic process according to claim 1, characterized in that: Trace element stock solution is also added to the simulated wastewater, with 5-5.5 mL of trace element stock solution added to every 15 L of simulated wastewater.

8. The method for treating urban domestic wastewater based on anaerobic ammonium oxidation reaction coupled with algae-bacteria symbiotic process according to claim 7, characterized in that: The trace element stock solution contains components with the following concentrations: 3515 mg / L FeCl3·6H2O, 359 mg / L MnCl2·4H2O, 75 mg / L CuSO4·5H2O, 300 mg / L ZnSO4·7H2O, and 375 mg / L CoCl2·6H2O.

9. The method for treating urban domestic wastewater based on anaerobic ammonium oxidation reaction coupled with algae-bacteria symbiotic process according to claim 1, characterized in that: In the step S3, a continuous water inlet mode is adopted, and the hydraulic retention time is adjusted by controlling the water inlet flow rate.

10. The method for treating urban domestic wastewater based on anaerobic ammonium oxidation reaction coupled with algae-bacteria symbiotic process according to any one of claims 1 to 9, characterized in that: In the step S3, light is provided inside the reactor and the temperature inside the reactor is controlled to be maintained in the range of 28-32°C.

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