High-sulfate municipal wastewater treatment method and system

Abstract

Embodiments of the present application provide a high sulfate municipal wastewater treatment method and system. The high sulfate municipal wastewater treatment method comprises: passing high sulfate municipal wastewater into an AnMBR system to obtain first intermediate wastewater after treatment; aerating the first intermediate wastewater in a regulating tank to reduce the content of dissolved sulfide in the wastewater to 40 mg / L to obtain second intermediate wastewater; and passing the second intermediate wastewater into a PN / A reaction system for treatment. The water quality indexes of the high sulfate municipal wastewater are: COD 400-500 mg / L, and sulfate-sulfur (SO4 2‑ -S) content 20-120 mg / L. The high sulfate municipal wastewater treatment system comprises an AnMBR system, a regulating tank, and a PN / A reaction system. The method and device provided by the present application can effectively remove sulfate-sulfur, COD, and N, and have high methane production. In addition, compared with the traditional activated sludge method, the method and device can reduce energy consumption and sludge production.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of sewage treatment, and in particular, relates to a high-sulfate municipal sewage treatment method and system. BACKGROUND

[0002] If municipal sewage containing sulfates is discharged into rivers, lakes and other surface water bodies without effective treatment, it will have an adverse effect on aquatic organisms. Sulfate ions in sewage can promote the formation of sulfates, thereby harming aquatic organisms and producing toxic gases. In addition, sulfate ions can react with other chemicals to form compounds that can corrode pipelines and other infrastructure. Therefore, it is urgent to efficiently treat municipal wastewater containing sulfates.

[0003] Currently, there are chemical precipitation, ion exchange, reverse osmosis and biological treatment methods for treating municipal sewage containing sulfates (Sahinkaya et al. 2018). The chemical precipitation method can effectively remove sulfate ions, but it produces a large amount of sludge and has high operating costs. Ion exchange and reverse osmosis can efficiently remove sulfate ions, but such processes consume a large amount of energy and have high installation and maintenance costs. Compared with other treatment methods, biological treatment is generally considered a more sustainable option because the process relies on natural processes and does not require the addition of chemicals or other treatment agents.

[0004] In view of this, the present application is proposed SUMMARY

[0005] The present application aims to, for example, provide a high-sulfate municipal sewage treatment method and system.

[0006] Embodiments of the present application can be implemented as follows:

[0007] In a first aspect, the present application provides a high-sulfate municipal sewage treatment method, comprising:

[0008] passing the high-sulfate municipal sewage into an AnMBR system for treatment to obtain first intermediate sewage;

[0009] aerating the first intermediate sewage in a regulating tank to reduce the dissolved S 2- content to 40 mg / L to obtain second intermediate sewage;

[0010] passing the second intermediate sewage into a PN / A reaction system for treatment;

[0011] The water quality indicators of the high-sulfate municipal sewage are: COD 400-500 mg / L, and sulfate-sulfur content 20-120 mg / L.

[0012] In an alternative embodiment, when the water quality index of the high-sulfur municipal sewage is COD 428.6-532.2 mg / L and sulfate-sulfur content is 23.6-26.8 mg / L, the hydraulic retention time of the AnMBR system is set to 11-13 h;

[0013] When the water quality index of the high-sulfur municipal sewage is COD 458.8-511 mg / L and sulfate-sulfur content is 37.8-41.8 mg / L, the hydraulic retention time of the AnMBR system is set to 11-13 h;

[0014] When the water quality index of the high-sulfur municipal sewage is COD 432.5-531.9 mg / L and sulfate-sulfur content is 37.7-44.1 mg / L, the hydraulic retention time of the AnMBR system is set to 5-7 h;

[0015] When the water quality index of the high-sulfur municipal sewage is COD 432.3-523.9 mg / L and sulfate-sulfur content is 105.2-116.6 mg / L, the hydraulic retention time of the AnMBR system is set to 5-7 h.

[0016] In an alternative embodiment, when the S / N of the second intermediate sewage is 0.01-0.32, the hydraulic retention time of the PN / A system is 22-26 h;

[0017] When the S / N of the second intermediate sewage is 0.25-0.34, the hydraulic retention time of the PN / A system is 10-14 h.

[0018] In an alternative embodiment, the aeration mode in the PN / A reaction system is that aeration is stopped for 50-70 min every 25-35 min of continuous aeration, and the cycle is repeated.

[0019] Alternatively, the aeration is the aerobic stage, and the DO value in the sewage is controlled to be 0.8-1.3 mg / L; the stop of aeration is the anoxic stage, and the DO value in the sewage is controlled to be 0.2-0.6 mg / L.

[0020] In an alternative embodiment, the processing temperature of the AnMBR system is 30-35℃.

[0021] In an alternative embodiment, the processing temperature of the PN / A reaction system is 28-32℃.

[0022] In an alternative embodiment, the sludge containing anaerobic fermentation bacteria and sulfate-reducing bacteria is inoculated in the AnMBR system, and the sludge concentration is 8-12 g / L;

[0023] The sludge containing anaerobic ammonia oxidation bacteria is inoculated in the PN / A reaction system;

[0024] Optionally, the sludge in the AnMBR system has a sludge age of 120-150 days, and the sludge in the PN / A reaction system has a sludge age of 14 days.

[0025] In a second aspect, the present application provides a high-sulfur municipal wastewater treatment system, comprising an AnMBR system, a conditioning tank, and a PN / A reaction system.

[0026] The effluent outlet of the AnMBR system is connected to the conditioning tank, and the effluent outlet of the conditioning tank is connected to the influent inlet of the PN / A reaction system.

[0027] In an optional embodiment, the AnMBR system comprises a membrane tank, a gas circulation unit, a membrane fouling detection unit, and a first influent and effluent unit.

[0028] The membrane tank is provided with a membrane module made of polyvinylidene fluoride, the gas circulation unit is used to circulate the headspace gas of the membrane tank to the bottom of the membrane module, the membrane fouling detection unit is used to detect the degree of membrane fouling, and the first influent and effluent unit is used to control the influent and effluent of the membrane tank.

[0029] In an optional embodiment, the PN / A reaction system comprises an SBR reactor, an aeration unit, a stirrer, and a second influent and effluent unit.

[0030] The aeration unit is used to aerate the SBR reactor at regular intervals, the stirrer is used to stir the SBR reactor, and the second influent and effluent unit is used to control the influent and effluent of the SBR reactor.

[0031] The beneficial effects of the embodiments of the present application include, for example:

[0032] The present application provides a high-sulfur municipal wastewater treatment method, which combines AnMBR and PN / A processes to achieve efficient removal of organic matter, sulfate, and total nitrogen in wastewater. The membrane bioreactor part combines anaerobic fermentation and membrane separation technology, and good effluent water quality can be obtained through the membrane bioreactor. The removal rates of COD and sulfate are much higher than those of traditional biological treatment technology, the sludge yield is lower than that of traditional anaerobic process, and the methane production is relatively high. At the same time, the coupled PN / A process as a subsequent treatment process of the membrane reactor achieves efficient removal of high ammonia nitrogen content in the effluent. Therefore, this method can effectively remove sulfate-sulfur, COD, and N, and has high methane production. In addition, compared with the traditional activated sludge method, the method provided by the present application can reduce energy consumption and environmental pollution, and effectively reduce greenhouse gas emissions. BRIEF DESCRIPTION OF DRAWINGS

[0033] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments. It should be understood that the following drawings only show some of the embodiments of the present application, and therefore should not be regarded as a limitation on the scope, and for those skilled in the art, other related drawings can also be obtained without creative labor on the basis of these drawings.

[0034] Figure 1 The structure of the high-sulfur municipal sewage treatment system provided by the present application is a schematic diagram.

[0035] Icon: 100-high-sulfur municipal sewage treatment system; 101-timer; 110-AnMBR system; 111-membrane tank; 112-gas circulation pipe; 113-septum pump; 114-first water inlet peristaltic pump; 115-first water outlet peristaltic pump; 116-membrane module; 117-gas flow meter; 120-regulating tank; 130-PN / A reaction system; 131-oxygenation pump; 132-flow meter; 133-SBR reactor; 134-stirrer; 135-second water inlet peristaltic pump; 136-second water outlet peristaltic pump. DETAILED DESCRIPTION

[0036] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the following will combine the drawings in the embodiments of the present application to make a clear and complete description of the technical solutions in the embodiments of the present application. Obviously, the described embodiments are some of the embodiments of the present application, but not all the embodiments. The components of the embodiments of the present application described and shown in the drawings can be arranged and designed in various different configurations.

[0037] Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the claimed present application, but only represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0038] It should be noted that: similar labels and letters represent similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0039] In the description of the present application, it should be noted that if the terms "upper", "lower", "inner", "outer" and the like indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship when the product of the present application is usually placed, which is only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present application.

[0040] In addition, if the terms "first", "second" and the like appear, they are only used to distinguish the description and cannot be understood as indicating or implying relative importance.

[0041] It should be noted that the features in the embodiments of the present application can be combined with each other without conflict.

[0042] Based on the problems pointed out in the background art, the inventors have made the following considerations:

[0043] Anaerobic membrane bioreactor (AnMBR) has many advantages (Maaz et al., 2019), membrane filtration process is more effective than other types of filtration process in removing pollutants, in addition, AnMBR has low sludge yield because the anaerobic digestion process has high renewable energy methane production. However, the nitrogen removal effect of membrane bioreactor for treating wastewater is not obvious, which may not meet the effluent standard of wastewater treatment plant. Coupled partial nitritation-anammox (PN / A) can effectively achieve wastewater denitrification, under the joint action of ammonia oxidizing bacteria and anammox bacteria, NH4 + -N in AnMBR effluent is converted to N2, thereby achieving the purpose of denitrification. Compared with traditional nitrification-denitrification denitrification process, this new denitrification process has the characteristics of low energy consumption, no need for external carbon source and low residual sludge yield (Wu et al., 2022), so it is considered to be the most economical denitrification technology.

[0044] The inventors consider combining the above two processes for treating high-sulfur municipal wastewater, but there is still a problem: the high sulfate-sulfur content in the wastewater has an adverse effect on the life activities of microorganisms in the sludge, and it is still a challenge to improve methane production or improve N treatment capacity. In view of this, the following scheme is proposed:

[0045] In this scheme, high-sulfur wastewater refers to wastewater with high sulfate-sulfur content, and low-sulfur wastewater refers to wastewater with low sulfate-sulfur content; sulfide product or sulfide refers to S 2- .

[0046] The application provides a high-sulfate municipal sewage treatment method, which comprises the following steps:

[0047] The high-sulfate municipal sewage is introduced into an AnMBR system for treatment to obtain first intermediate sewage;

[0048] The first intermediate sewage is subjected to aeration in a regulating tank to reduce the content of S 2- to 40 mg / L to obtain second intermediate sewage;

[0049] The second intermediate sewage is introduced into a PN / A reaction system for treatment;

[0050] The water quality indexes of the high-sulfate municipal sewage are as follows: COD is 400-500 mg / L, and sulfate-sulfur content is 20-120 mg / L.

[0051] The AnMBR system can effectively remove sulfur and COD in the sulfur-containing municipal sewage, and the sludge yield of the system is low and the methane yield is high; however, the AnMBR system has no obvious effect on the removal of nitrogen in the sewage, in the application, the effluent of the AnMBR system is further treated by using the PN / A reaction system to effectively remove nitrogen and convert ammonia nitrogen into nitrogen; however, due to the high sulfate content of the raw water, the effluent contains high-concentration sulfide product (S 2- ) after being treated by the AnMBR system, and the activity of microorganisms in the PN / A reaction system is affected when the effluent of the AnMBR system is directly introduced into the PN / A reaction system, which is not conducive to the removal of nitrogen, therefore, the content of S 2- in the dissolved ions in the sewage is reduced to 40 mg / L in the regulating tank before the effluent of the AnMBR system is introduced into the PN / A reaction system, so that the PN / A reaction system has a good treatment effect on nitrogen in the sewage.

[0052] In summary, the high-sulfate municipal sewage treatment method provided by the application combines the AnMBR and PN / A processes, and realizes the efficient removal of organic matter, sulfate and total nitrogen in the sewage; the membrane bioreactor part combines anaerobic fermentation and membrane separation technology, and good effluent water quality can be obtained through the membrane bioreactor, the removal rates of COD and sulfate are much higher than those of traditional biological treatment technology, the sludge yield is lower than that of the traditional anaerobic process, and the methane yield is relatively high; meanwhile, the coupled PN / A process as a subsequent treatment process of the membrane reactor realizes the efficient removal of high ammonia nitrogen content in the effluent. Compared with the traditional activated sludge method, the method provided by the application can reduce energy consumption and sludge yield, and effectively reduce greenhouse gas emissions.

[0053] Specifically, the AnMBR system is inoculated with flocculent sludge containing anaerobic fermentation bacteria and sulfate-reducing bacteria; and the PN / A reaction system is inoculated with granular sludge containing ammonia-oxidizing bacteria and anaerobic ammonia-oxidizing bacteria.

[0054] Optionally, the sludge inoculated into the AnMBR system has a sludge age of 120-150 days, and the sludge in the PN / A reaction system has a sludge age of 14 days.

[0055] Preferably, to enable the microorganisms in the AnMBR system to more efficiently treat wastewater, before formal wastewater treatment, low-sulfur-content wastewater with a sulfate concentration of 1 / 12-1 / 2 of the sulfate concentration in high-sulfur municipal wastewater is introduced into the AnMBR system for 5-50 hours to achieve the effect of domesticating the microorganisms in the AnMBR system.

[0056] Further, to achieve better removal of COD and S and higher methane production in the AnMBR system:

[0057] When the water quality indicators of the high-sulfur municipal wastewater are: COD 428.6-532.2 mg / L, and sulfate-sulfur content 23.6-26.8 mg / L, the hydraulic retention time of the AnMBR system is set to 11-13 hours.

[0058] When the water quality indicators of the high-sulfur municipal wastewater are: COD 458.8-511 mg / L, and sulfate-sulfur content 37.8-41.8 mg / L, the hydraulic retention time of the AnMBR system is set to 11-13 hours.

[0059] When the water quality indicators of the high-sulfur municipal wastewater are: COD 432.5-531.9 mg / L, and sulfate-sulfur content 37.7-44.1 mg / L, the hydraulic retention time of the AnMBR system is set to 5-7 hours.

[0060] When the water quality indicators of the high-sulfur municipal wastewater are: COD 432.3-523.9 mg / L, and sulfate-sulfur content 105.2-116.6 mg / L, the hydraulic retention time of the AnMBR system is set to 5-7 hours.

[0061] Preferably, to achieve better COD and S treatment effects and more methane production, the treatment temperature of the AnMBR system 110 is 30-35°C (e.g., 30°C, 32°C, 34°C, or 35°C).

[0062] Preferably, to enable the microorganisms in the PN / A reaction system to more efficiently treat the sewage, the low-PN / A reaction system sewage pretreatment is performed for 12-100 hours before formal sewage treatment, so as to achieve the effect of domesticating the microorganisms in the PN / A reaction system.

[0063] Further, to achieve a better N treatment effect in the PN / A reaction system:

[0064] when the S / N of the second intermediate sewage is 0.01-0.32, the hydraulic retention time is 22-26 hours;

[0065] when the S / N of the second intermediate sewage is 0.25-0.34, the hydraulic retention time is 10-14 hours.

[0066] Further, to better avoid the community migration of dominant NOB species under the condition of low ammonia nitrogen, the aeration mode in the PN / A reaction system is to stop aeration for 25-35 minutes every 50-70 minutes of continuous aeration, and the cycle is repeated.

[0067] Optionally, the aeration is the aerobic stage, and the DO value in the sewage is controlled to be 0.8-1.3 mg / L; the stop of aeration is the anoxic stage, and the DO value in the sewage is controlled to be 0.2-0.6 mg / L.

[0068] Preferably, to better achieve the N treatment effect, the treatment temperature of the PN / A reaction system is 28-32°C (for example, 28°C, 29°C, 30°C or 32°C).

[0069] As shown in Figure 1 The present application also provides a high-sulfur municipal sewage treatment system 100, which comprises an AnMBR system 110, a conditioning tank 120 and a PN / A reaction system 130.

[0070] The effluent outlet of the AnMBR system 110 is in communication with the conditioning tank 120, and the effluent outlet of the conditioning tank 120 is in communication with the influent inlet of the PN / A reaction system 130.

[0071] Specifically, the AnMBR system 110 comprises a membrane tank 111, a gas circulation unit, a membrane pollution detection unit and a first water inlet and outlet unit.

[0072] The membrane tank 111 is provided with a membrane assembly 116 made of polyvinylidene fluoride, the gas circulation unit is used to circulate the headspace gas of the membrane tank 111 to the bottom of the membrane assembly 116, the membrane pollution detection unit is used to detect the degree of membrane pollution, and the first water inlet and outlet unit is used to control the water inlet and outlet of the membrane tank 111.

[0073] Further, the gas circulation unit comprises a gas circulation pipe 112 and a diaphragm pump 113 arranged on the gas circulation pipe 112, the diaphragm pump 113 circulates a part of the gas produced above the AnMBR system 110 to the bottom of the membrane assembly 116, and the circulating floating gas can realize hydraulic mixing of the system and removal of sludge adsorbed to the membrane surface; the membrane pollution detection unit periodically detects the degree of membrane pollution, and if the degree of pollution is high, timely backwashing or replacing the membrane assembly 116 is performed; the first water inlet and outlet unit comprises a first water inlet pipe, a first water inlet peristaltic pump 114 arranged on the first water inlet pipe, and the sewage is introduced into the AnMBR system 110 through the first water inlet peristaltic pump 114, and the first water inlet and outlet unit further comprises a first water outlet pipe and a first water outlet peristaltic pump 115 arranged on the first water outlet pipe, and the treated sewage in the AnMBR system 110 is discharged into the adjusting tank 120 through the first water outlet peristaltic pump 115.

[0074] Further, the AnMBR system 110 further comprises an exhaust pipe, and a gas flow meter 117 is arranged on the exhaust pipe, and the exhaust pipe is used to exhaust the methane produced in the AnMBR system 110.

[0075] Specifically, the PN / A reaction system 130 comprises an SBR reactor 133, an aeration unit, a stirrer 134, and a second water inlet and outlet unit.

[0076] The aeration unit is used for aeration into the SBR reactor 133 at a time, the stirrer 134 is used for stirring in the SBR reactor 133, and the second water inlet and outlet unit is used for controlling the water inlet and outlet of the SBR reactor 133.

[0077] Specifically, the aeration unit comprises an aeration pipe, an oxygenation pump 131, a timer 101, and a flow meter 132, the aeration pipe is in communication with the aerator inside the reactor, the flow meter 132 is arranged on the aeration pipe, the end of the aeration pipe is connected with the oxygenation pump 131, and the oxygenation pump 131 is in communication connection with the timer 101, under the timing action of the timer 101, the oxygenation pump 131 intermittently introduces air into the SBR reactor 133 for aeration. The stirring part of the stirrer 134 is located inside the reactor to stir the sewage, so as to accelerate the treatment process; the second water inlet and outlet unit comprises a second water inlet pipe, a second water inlet peristaltic pump 135 arranged on the second water inlet pipe, and a timer 101 in communication connection with the second water inlet peristaltic pump 135, the second water inlet peristaltic pump 135 pumps the sewage with reduced S content in the adjusting tank 120 into the SBR reactor 133 at a time; the second water inlet and outlet unit further comprises a second water outlet pipe, a second water outlet peristaltic pump 136 arranged on the second water outlet pipe, and a timer 101 in communication connection with the second water outlet peristaltic pump 136, and the second water outlet peristaltic pump 136 pumps out the treated water in the SBR reactor 133 at a time.

[0078] Experimental example

[0079] The working volume of the AnMBR membrane tank is 3L. During the start-up phase, excess sludge from the municipal wastewater treatment plant is inoculated into the AnMBR. The concentration of mixed liquor volatile suspended solids (MLVSS) in the AnMBR is controlled at 6-8g / L, the reactor temperature is set at 35℃, and the sludge age is 120-150 days during stable operation.

[0080] The simulated high-sulfur urban wastewater was prepared using a configuration where the carbon source was glucose and sodium acetate, the sulfate source was sodium sulfate, and the nitrogen source was ammonium chloride. Five sets of this simulated high-sulfur urban wastewater were prepared in total, and the specific water quality indicators and hydraulic retention times are shown in Table 1.

[0081] Table 1. Water quality and hydraulic retention time in the AnMBR system for each experimental group.

[0082]

[0083]

[0084] In the table above, the sulfur content increases sequentially from the start-up group to the fourth group. When conducting the experiment, the start-up group experiment was carried out first in the same reactor, and then the first to fourth group experiments were carried out in sequence. The start-up group reaction stage is equivalent to the domestication stage of the microorganisms in the reactor before the first group experiment, while the first group experiment is equivalent to the domestication stage of the second group experiment, and so on.

[0085] After the AnMBR reactor completes its reaction, the effluent is fed into an equalization tank for further treatment of the wastewater. 2- After the concentration was below 40 mg / L, the water quality of each group was measured, and the hydraulic retention time of the PN / A reaction system reactor was set according to the water quality. The details are shown in Table 2.

[0086] Table 2. Inlet water conditions and hydraulic retention time of the PN / A reaction system

[0087]

[0088] A laboratory-scale sequencing batch reactor (SBR) with a working volume of 2L was used to implement a single-stage partial nitrification-anaerobic ammonia oxidation (PN / A) process. The reactor was inoculated with granular sludge containing anaerobic ammonia oxidizing bacteria that had been cultured for many years.

[0089] PN / A system water distribution process: Water is pumped from the equalization tank at regular intervals every day by a peristaltic pump (BT300-3J) with flow control to complete the continuous water inflow and outflow. Aeration is stopped 10 minutes before each water outflow, and the water inflow and outflow are controlled within 30 minutes (the water inflow and outflow rate is 66ml / min each time).

[0090] The speed of the electric agitator arranged at the top of the SBR reactor is 90 rpm, the gas flow rate is controlled in the range of 5-15 ml / min by a gas flow meter, and the gas circulation is started from 0:00 every day, continuously aerated for 30 minutes, then stopped for 1 hour, and then continuously aerated for 30 minutes, and the cycle is repeated. The influent DO is controlled to be less than 0.2 mg / L, the DO in the reactor is controlled to be 0.2-0.6 mg / L in the anoxic stage, and the DO is controlled to be 0.6-1.4 mg / L in the aerobic stage. The outer layer of the reactor uses a silicone rubber heating plate to keep the water temperature at 30±2℃.

[0091] The granular sludge of anaerobic ammonia oxidation bacteria is cultivated by using tap water, NH4Cl and NaHCO3 to synthesize sewage in the PN / A start-up stage, the initial ammonia nitrogen concentration is controlled to be 100 mg / L, the pH is controlled to be between 7.5-8.0, the hydraulic retention time (HRT) is 24 hours, the reactor is intermittently aerated, the DO is 0.4-0.6 mg / L in the non-aeration state, and the DO is 0.6-1.4 mg / L in the aeration state.

[0092] After the start-up stage is over, the water discharged from the adjusting tank is introduced into the SBR reactor for treatment.

[0093] The sewage treatment effects of the whole system on each experimental group are shown in Table 3:

[0094] Table 3 Sewage treatment effects of each experimental group

[0095]

[0096] As can be seen from the above table, the four experimental groups provided in the experimental example have very good treatment effects on the simulated high-sulfur municipal sewage, and have high methane production.

[0097] Comparison group 1

[0098] This comparison group is compared with the fourth group in the experimental example, and the difference between the two is that the effluent of the AnMBR reaction system is not aerated in the adjusting tank but directly introduced into the PN / A reaction system.

[0099] Comparison group 2

[0100] This comparison group is compared with the first group in the experimental example, and the difference between the two is that the AnMBR reaction system does not set up a start-up group to domesticate anaerobic fermentation and sulfate-reducing bacteria before formal reaction.

[0101] Comparison group 3

[0102] This comparison group is compared with the first group in the experimental example, and the difference between the two is that the PN / A reaction system does not set up a start-up stage to domesticate anaerobic ammonia oxidation bacteria before formal reaction.

[0103] The treatment results for each control group are shown in Table 4:

[0104] Table 4. Wastewater treatment effects of each comparison group

[0105]

[0106] Table 4 shows that the treatment effects of each control group were worse than those of the corresponding experimental groups. Control group 1 had a significantly lower TN removal rate than group 4, indicating that aeration to reduce S was necessary before PN / A treatment. 2- The concentration significantly improved the TN removal rate. Comparing control group 2 with group 1, group 1 showed slightly higher COD and sulfate removal rates, as well as slightly higher methane production. This is likely due to the anaerobic fermentation and sulfate-reducing bacteria in the reactor not yet adapting to the high-sulfur environment in the early stages of treatment. Therefore, appropriate acclimatization of the anaerobic fermentation and sulfate-reducing bacteria in the reactor before formal treatment can improve the treatment effect during formal treatment. Comparing control group 3 with group 1, group 1 showed slightly higher TN removal rate. This is likely due to the anaerobic ammonia-oxidizing bacteria in the reactor not yet adapting to the high-sulfur environment in the early stages of treatment. Therefore, appropriate acclimatization of the microorganisms in the reactor before formal treatment can improve the treatment effect during formal treatment.

[0107] In summary, the high-sulfate urban wastewater treatment method provided by this invention addresses the drawbacks of traditional biological wastewater treatment processes, such as high sludge production and large land area requirements, by combining AnMBR and PN / A processes. By integrating anaerobic digestion and the PN / A process into the wastewater treatment process, it achieves efficient energy recovery and deep autotrophic denitrification. This process is first based on a membrane bioreactor design, integrating membrane filtration technology into anaerobic biological treatment to efficiently decompose and remove organic matter from wastewater and generate recyclable energy. The coupled nitrification / anaerobic ammonia oxidation process utilizes ammonia-oxidizing bacteria and anaerobic ammonia-oxidizing bacteria for autotrophic denitrification, converting ammonia in the anaerobic digestion effluent into nitrogen gas. Therefore, the high-sulfate urban wastewater treatment method provided by this invention can effectively remove sulfur, COD, and nitrogen from wastewater.

[0108] The above are merely specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A high-sulfate municipal wastewater treatment method, characterized by, The method comprises the following steps: The high-sulfate municipal sewage is treated in the AnMBR system to obtain first intermediate sewage; aerating the first intermediate sewage in a conditioning tank to dissolve S in the sewage 2- obtaining a second intermediate sewage after the content is reduced to 40 mg / L; The second intermediate sewage is treated in the PN / A reaction system; The water quality index of the high-sulfate municipal sewage is: COD 400-500 mg / L, and sulfate-sulfur content is 20-120 mg / L; The AnMBR system is inoculated with sludge containing anaerobic fermentation bacteria and sulfate-reducing bacteria, and the sludge concentration is 8-12 g / L; When the water quality index of the high-sulfate municipal sewage is: COD 428.6-532.2 mg / L, and sulfate-sulfur content is 23.6-26.8 mg / L, the hydraulic retention time of the AnMBR system is set to 11-13 h; When the water quality index of the high-sulfate municipal sewage is: COD 458.8-511 mg / L, and sulfate-sulfur content is 37.8-41.8 mg / L, the hydraulic retention time of the AnMBR system is set to 11-13 h; When the water quality index of the high-sulfate municipal sewage is: COD 432.5-531.9 mg / L, and sulfate-sulfur content is 37.7-44.1 mg / L, the hydraulic retention time of the AnMBR system is set to 5-7 h; When the water quality index of the high-sulfate municipal sewage is: COD 432.3-523.9 mg / L, and sulfate-sulfur content is 105.2-116.6 mg / L, the hydraulic retention time of the AnMBR system is set to 5-7 h.

2. The high-sulfate municipal wastewater treatment method according to claim 1, characterized in that, When the S / N of the second intermediate sewage is 0.01-0.32, the hydraulic retention time of the PN / A system is 22-26 h; When the S / N of the second intermediate sewage is 0.25-0.34, the hydraulic retention time of the PN / A system is 10-14 h.

3. The high-sulfate municipal wastewater treatment method according to claim 1, characterized in that, The aeration mode in the PN / A reaction system is that aeration is stopped for 50-70 min every 25-35 min of continuous aeration, and the cycle is repeated. Optionally, the aeration is the aerobic stage, and the DO value in the sewage is controlled to be 0.8-1.3 mg / L; the stop of aeration is the anoxic stage, and the DO value in the sewage is controlled to be 0.2-0.6 mg / L.

4. The high-sulfate municipal wastewater treatment method of claim 1, wherein, The processing temperature of the AnMBR system is 30-35 ℃.

5. The high-sulfate municipal wastewater treatment method of claim 1, wherein, The processing temperature of the PN / A reaction system is 28-32 ℃.

6. The method for treating high-sulfate municipal sewage according to claim 1, wherein the sludge inoculated in the PN / A reaction system contains anaerobic ammonia oxidation bacteria. Optionally, the sludge age of the sludge inoculated in the AnMBR system is 120-150 days, and the sludge age of the sludge in the PN / A reaction system is 14 days. The method is applied to a high-sulfate municipal sewage treatment system, which comprises an AnMBR system, a regulating tank and a PN / A reaction system; 7. The high-sulfate municipal wastewater treatment method according to any one of claims 1-6, characterized in that, The water outlet of the AnMBR system is communicated with the regulating tank, and the water outlet of the regulating tank is communicated with the water inlet of the PN / A reaction system. The AnMBR system comprises a membrane tank, a gas circulation unit, a membrane pollution detection unit and a first water inlet and outlet unit.

8. The high-sulfate municipal wastewater treatment method according to claim 7, characterized in that, ​ The membrane pool is provided with a membrane assembly made of polyvinylidene fluoride, the gas circulation unit is used for circulating the headspace gas of the membrane pool to the bottom of the membrane assembly, the membrane pollution detection unit is used for detecting the degree of membrane pollution, and the first water inlet and outlet unit is used for controlling the water inlet and outlet of the membrane pool.

9. The high-sulfate municipal wastewater treatment method according to claim 7, characterized in that, The PN / A reaction system comprises an SBR reactor, an aeration unit, a stirrer and a second water inlet and outlet unit. The aeration unit is used for aeration in the SBR reactor at a time, the stirrer is used for stirring in the SBR reactor, and the second water inlet and outlet unit is used for controlling the water inlet and outlet of the SBR reactor.

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