CN115448459A - A Membrane Fouling Control Method for Autotrophic-Heterotrophic Granular Sludge MBR Denitrification System of Urban Sewage and Its Application - Google Patents

Abstract

The invention relates to the technical field of water treatment, in particular to a membrane pollution control method for an urban sewage autotrophic-heterotrophic granular sludge MBR (membrane bioreactor) denitrification system and application thereof. The method comprises the steps of treating urban sewage by autotrophic-heterotrophic granular sludge and a hollow fiber membrane component to obtain produced water; carrying out on-line hydraulic backwashing on the hollow fiber membrane component by using the produced water; then, carrying out on-line chemical backwashing on the hollow fiber membrane component by using a chemical agent; the urban sewage treatment, the online hydraulic backwashing and the online chemical backwashing are sequentially carried out once respectively to form an online backwashing period, and the membrane pollution control method is the cyclic operation of a plurality of online backwashing periods. According to the invention, by circularly operating the online backwashing period consisting of urban sewage treatment, online hydraulic backwashing and online chemical backwashing, the membrane module in the membrane bioreactor can be periodically cleaned, the membrane pollution behavior can be controlled in real time, and the permeability of the membrane can be effectively maintained.

Description

Membrane pollution control method for autotrophic-heterotrophic granular sludge MBR denitrification system of urban sewage law and its application

technical field

The invention relates to the technical field of water treatment, in particular to a method for controlling membrane pollution in an autotrophic-heterotrophic granular sludge MBR denitrification system for urban sewage and an application thereof.

Background technique

With the development of industry and the improvement of people's living standards, the problem of water eutrophication caused by excessive nitrogen discharge needs to be solved urgently, and urban sewage is one of the sources of water environmental pollution in my country.

The anaerobic ammonium oxidation (Anammox) process has the characteristics of economy and high efficiency, and has received extensive attention in the industry. The anaerobic ammonium oxidation biological denitrification process technology is based on the anaerobic ammonium oxidation bacteria (AnAOB) using ammonia nitrogen and nitrite nitrogen as substrates to achieve a bioautotrophic denitrification process, which is usually used in the treatment of high nitrogen wastewater ( Anaerobic digestion of sludge, landfill leachate, etc.).

Recent studies have found that Anammox biological denitrification technology can also be used for the treatment of urban low-nitrogen sewage. In addition, because urban sewage contains a certain concentration of organic matter, the process of nitrification, anammox and denitrification (Simultaneous partial Nitrification, Anammox and Denitrification, SNAD) has also emerged as the times require. This process can not only remove ammonia nitrogen in urban sewage, but also use organic matter in sewage to further remove nitrate nitrogen (accounting for about 10% of total nitrogen) produced by anaerobic ammonium oxidation reaction, so as to achieve deep removal in a single-stage process Nitrogen and carbon removal. Among them, anammox is the core reaction process of the SAND process. However, the effective retention of anammox bacteria (AnAOB) is crucial for the realization of anammox (Anammox) and nitrification, and anammox coupled heterotrophic denitrification. (SNAD) reaction process is crucial. However, there are problems such as slow growth of anammox bacteria and easy loss of flocs. Therefore, there are technical difficulties in forming granular sludge of anammox bacteria.

Utilizing the high-efficiency separation of the hollow fiber membrane module of the membrane bioreactor (MBR), it can intercept microorganisms, which is of great significance for the formation of nitrosation, anaerobic ammonium oxidation coupled heterotrophic denitrification (SNAD) granular sludge. However, when membrane bioreactors achieve high-efficiency separation, membrane fouling problems will inevitably occur; how to effectively inhibit the membrane fouling behavior caused by granular sludge clogging membrane bioreactors has become the key to maintaining the stability of membrane bioreactor systems .

At present, online backwashing of membrane modules mainly includes two backwashing modes: hydraulic backwashing and chemical backwashing. Hydraulic backwashing cannot effectively remove the residual pollutants in the membrane pores; the main agent for chemical backwashing is sodium hypochlorite (NaClO). Due to the concentration of NaClO and the frequency of backwashing, it is easy to stress the microorganisms in the membrane bioreactor, resulting in membrane fouling. Effective solution.

Contents of the invention

In view of the above technical problems, the present invention provides a method for controlling membrane pollution in an autotrophic-heterotrophic granular sludge MBR denitrification system of urban sewage and its application. The membrane fouling control method can effectively solve the membrane fouling problem, effectively maintain the membrane permeability, and avoid microbial stress, thereby maintaining the stable operation of the membrane bioreactor.

In order to solve the problems of the technologies described above, the present invention adopts the following technical solutions:

In a first aspect, the present invention provides a method for controlling membrane pollution in an urban sewage autotrophic-heterotrophic granular sludge MBR denitrification system, the method comprising: treating urban sewage through autotrophic-heterotrophic granular sludge and hollow fiber membrane modules, Obtain produced water; use the produced water to perform online hydraulic backwashing on the hollow fiber membrane module; then use chemical agents to perform online chemical backwash on the hollow fiber membrane module; sequentially perform the treatment of urban sewage, the online hydraulic backwashing and Each of the on-line chemical backwashing is an on-line backwashing cycle, and the membrane pollution control method is cyclic operation of several on-line backwashing cycles.

In the membrane bioreactor of the present invention, after the urban sewage is biologically denitrified through the autotrophic-heterotrophic granular sludge layer, the sludge and organic matter are filtered out through the hollow fiber membrane module, and the produced water is discharged; the produced water is used In the online hydraulic backwashing of the hollow fiber membrane module, after removing the pollutants attached to the hollow fiber membrane module, the online chemical backwash is used to further oxidize and decompose the membrane pollutants remaining on the membrane module; Backwashing and online chemical backwashing completely remove membrane pollutants from hollow fiber membrane modules. The membrane fouling control method can effectively solve the membrane fouling problem of the membrane bioreactor, effectively maintain the membrane permeability, and effectively prolong the operation period of the membrane bioreactor. In the embodiment of the present invention, treatment of urban sewage, online hydraulic backwashing and online chemical backwashing each constitute an online backwashing cycle. By circulating several online backwashing cycles, periodic cleaning of the membrane bioreactor can be realized, the membrane fouling behavior can be controlled in real time, and the permeability of the membrane can be effectively maintained.

Preferably, the online backwash cycle is 10-30min; the online backwash cycle includes 8-28min for urban sewage treatment, 1.0-1.2min for online hydraulic backwash and 1.0-1.2min for online chemical backwash; The produced water flux of the sewage is 6.7L/(m ² ·h); the hydraulic backwash flux is 3-4 times of the produced water flux; the chemical backwash flux is the 3-4 times of the amount; the chemical agent for chemical backwashing is 50-150mg/L NaClO solution.

In the embodiment of the present invention, by optimizing the above-mentioned online backwash cycle, the water production efficiency of the membrane bioreactor is guaranteed; by optimizing the time of hydraulic backwash, the concentration of chemical agents and the time of chemical backwash, the failure of microbial stress can be avoided occur. Therefore, the above-mentioned preferred online backwash cycle, hydraulic backwash time, concentration of chemical agents and chemical backwash time can effectively maintain membrane permeability and slow down membrane fouling while ensuring the denitrification and carbon removal efficiency of membrane bioreactor. rate, thereby effectively prolonging the operation period of the membrane bioreactor and ensuring the water production efficiency, which has good engineering application value.

In the embodiment of the present invention, the online backwashing can effectively remove the membrane pollutants of the hollow fiber membrane module, thereby restoring the permeability of the membrane. Compared with the offline cleaning of the membrane module, it has the advantages of simple and convenient operation steps.

In the embodiment of the present invention, when the concentration of the chemical agent NaClO is lower than 50 mg/L, due to the low concentration of the chemical agent, the chemical cleaning of membrane pollutants is not complete, thereby affecting the efficiency of membrane pollution removal; when the concentration of the chemical agent NaClO is higher than 150 mg /L, the activities of aerobic ammonium oxidizing bacteria (AerAOB), anaerobic ammonium oxidizing bacteria (AnAOB) and heterotrophic denitrifying bacteria (DNB) will be affected, resulting in microbial stress, leading to the generation of membrane fouling factors, and then affecting Membrane fouling removal efficiency. Therefore, the concentration of the above-mentioned preferred chemical agents can prevent the occurrence of microbial stress and ensure the complete removal of membrane fouling substances. The concentration of the chemical agent NaClO is preferably 50-100 mg/L.

In the embodiment of the present invention, the shorter the online backwashing period, the higher the frequency will be, and the higher backwashing frequency will reduce the treatment capacity of the membrane bioreactor for urban sewage, thereby reducing the water production of the membrane bioreactor, thereby reducing Water production efficiency. Therefore, choosing a reasonable online backwash cycle is very important for water production efficiency.

In the second aspect, the present invention also provides the application of the above-mentioned membrane pollution control method in the treatment of urban sewage by using a membrane bioreactor.

Preferably, the membrane bioreactor is an upflow microautotrophic-heterotrophic granular sludge layer membrane bioreactor; the upflow microautotrophic-heterotrophic granular sludge layer contains an aeration disc connected to The aeration pump can be used for intermittent aeration.

Preferably, the upflow microautotrophic-heterotrophic granular sludge layer of the membrane bioreactor is used to remove nitrogen and carbon from urban sewage, and then the hollow fiber membrane module is used to separate the granular sludge and organic matter to obtain produced water.

Preferably, the operating conditions of the membrane bioreactor include: controlling the temperature of the membrane bioreactor to 30±2°C; the pH value being 7-8, the hydraulic retention time of the membrane bioreactor being 9.6-11.2h, and the The water production flux of the reactor is 9.7-11.3L; the reflux ratio of the membrane bioreactor is 31.2-36.5, and the rising flow rate is between 2.6-3.5m/h; the membrane bioreactor uses an aeration pump for intermittent aeration, Stop aeration ratio: 5-7min:1min, aeration rate is 0.08-0.10L/min, maintain dissolved oxygen at 0.3-0.6mg/L.

In the embodiment of the present invention, urban sewage enters water from the bottom of the upflow micro-aerobic autotrophic-heterotrophic granular sludge layer membrane bioreactor, and after denitrification and carbon removal through the autotrophic-heterotrophic granular sludge layer from bottom to top, passes through The hollow fiber membrane module realizes the separation of mud and water and obtains produced water. The form of autotrophic-heterotrophic granular sludge can be maintained in the membrane bioreactor, which has a good sedimentation ratio and can form obvious mud layer and water layer, and the intermittent micro-aerobic aeration of the aeration pump can affect the hollow fiber membrane The membrane surface of the module is aerated and scoured to reduce the accumulation rate of sludge on the membrane surface.

Preferably, the autotrophic-heterotrophic granular sludge of the upflow micro-aerobic autotrophic-heterotrophic granular sludge layer contains active functional bacteria, and the active functional bacteria are composed of aerobic ammonia oxidizing bacteria, anaerobic ammonia oxidizing bacteria and It is composed of heterotrophic denitrifying bacteria, and the average particle diameter of the autotrophic-heterotrophic granular sludge is 1.00-2.00mm.

In the embodiment of the present invention, the active functional bacteria contained in the autotrophic-heterotrophic granular sludge can remove the ammonia nitrogen in the urban sewage, and can also use the organic matter in the sewage to further remove the nitrate nitrogen produced by the anammox reaction, thereby Realize the denitrification and carbon removal of urban sewage by autotrophic-heterotrophic granular sludge layer.

Preferably, the material of the hollow fiber membrane module is PVDF, the transmembrane pressure difference of the hollow fiber membrane module is 5.0-10.5kpa, and the permeate flux is 6.7L/(m ² ·h).

In the embodiment of the present invention, the hollow fiber membrane module can completely intercept the flocs of anammox bacteria, thereby avoiding the loss of anammox bacteria, and can effectively improve the formation efficiency of anammox bacteria granular sludge. It is of great significance to quickly form autotrophic-heterotrophic granular sludge with nitrification, anammox coupled with heterotrophic denitrification and maintain the stability of granular sludge.

In the embodiment of the present invention, after the urban sewage is treated by a membrane bioreactor, the total nitrogen and COD of the obtained water are greater than 90%.

The membrane bioreactor of the present invention combines the autotrophic-heterotrophic granular sludge, the intermittent aeration of the aeration pump to wash the membrane surface and real-time online backwashing, while ensuring the stable operation performance of the membrane bioreactor, it can also effectively Membrane fouling behavior is slowed down, and the system operation cycle of the membrane bioreactor is extended; the denitrification and carbon removal function of the autotrophic-heterotrophic granular sludge of the membrane bioreactor and the high-efficiency separation of organic matter of the hollow fiber membrane module and the continuation of the granular sludge Operation, can efficiently treat urban nitrogen-containing organic wastewater, efficiently degrade total nitrogen and COD in wastewater, realize water resource recycling, avoid environmental pollution, and can also promote autotrophic-heterotrophic granular sludge membrane bioreactor in urban sewage Generalization and application of the processing field.

Description of drawings

Figure 1 shows the TN removal rate, COD removal rate and activity of functional bacteria AerAOB, AnAOB and DNB in the upflow micro-aerobic autotrophic-heterotrophic granular sludge membrane bioreactor at different backwashing frequencies/concentrations.

Figure 2 is a diagram of the TMP change of the upflow micro-aerobic autotrophic-heterotrophic granular sludge membrane bioreactor under different backwashing frequencies/concentrations.

detailed description

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with specific embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention, not to limit the present invention.

In the existing technology of urban sewage treatment, the high-efficiency separation of the hollow fiber membrane module of the membrane bioreactor (MBR) can be used to intercept microorganisms. The formation of mud is of great significance. However, when membrane bioreactors achieve high-efficiency separation, the problem of membrane fouling will inevitably occur. The mechanism of membrane fouling is that after the granular sludge flows into the membrane module, it accumulates on the membrane surface of the membrane module, and blocks or forms gel inside the membrane pores, thereby forming membrane fouling.

The present invention uses online hydraulic backwashing and online chemical backwashing in combination to completely remove the membrane pollutants accumulated in the membrane holes and membrane surfaces of the hollow fiber membrane module; the membrane pollution control method can effectively solve the membrane pollution of the membrane bioreactor problems, effectively maintain membrane permeability, and effectively prolong the operation period of membrane bioreactors.

The invention reversely injects the produced water obtained by treating urban sewage into the membrane module through online hydraulic backwashing to realize the removal of some particles or colloidal pollutants on the surface of the membrane module; and then reversely injects chemical agent solution into the membrane module through online chemical backwashing , to realize the removal of the pollutants inside the membrane pores and the gel pollutants on the surface of the membrane module. On-line hydraulic backwashing and on-line chemical backwashing are combined into a cleaning process. Continuously running this cleaning process intermittently can effectively remove membrane fouling substances and restore membrane permeability, which is of great significance to the stable operation of membrane bioreactors. Moreover, the membrane fouling control method provided by the present invention is an online cleaning method, which has simpler steps and more convenient operation than offline cleaning of membrane modules.

The present invention will be further described below in conjunction with specific embodiments.

Example 1

This embodiment provides a method for controlling membrane pollution in an autotrophic-heterotrophic granular sludge MBR denitrification system for urban sewage, which mainly includes the following steps:

Step 1): Municipal sewage enters the upflow type micro-oxygen auto-oxygen-hetero-oxygen granular sludge layer membrane bioreactor, and after being treated with autotrophic-heterotrophic granular sludge, the produced water is discharged through the hollow fiber membrane module. Autotrophic-heterotrophic granular sludge contains active functional bacteria composed of ammonium oxidizing bacteria, anammox bacteria and heterotrophic denitrifying bacteria. When the membrane bioreactor is running, the temperature and pH of the urban sewage are controlled to be 30±2°C and 7-8 respectively, the hydraulic retention time (HRT) in the membrane bioreactor is controlled at 11.2h, and the water production rate is 9.7L/d; Membrane bioreactor is set with internal reflux, the reflux ratio is controlled at 36.5, and the ascending flow rate is controlled at about 2.8m/h; the membrane bioreactor uses an aeration pump for intermittent aeration, the stop aeration ratio: 5min:1min, and the aeration rate is 0.08 L/min, maintain dissolved oxygen at 0.3-0.6mg/L; the average concentrations of ammonia nitrogen and COD in the influent water are 50.2mg/L and 252.5mg/L respectively. The material of the hollow fiber membrane module is PVDF, the length is 18cm, and the effective membrane The area is 0.075m ² , and the permeate flux is 6.7L/(m ² ·h).

Step 2): Set every 10 minutes of the membrane bioreactor as an online backwash cycle. In each cycle, the hollow fiber membrane module first produces water for 8 minutes, and the water flux is 6.7L/(m ² ·h), and then stops the production. Water, use the produced water to carry out hydraulic backwashing on the hollow fiber membrane module for 1min, the backwashing flux of water is 22.3L/(m ² ·h), stop hydraulic backwashing; then carry out chemical backwashing on the hollow fiber membrane module for 1min, chemical The backwash flux of the agent is 22.3L/(m ² ·h), and the backwash chemical agent is 50mg/L NaClO solution. Cycle through the in-line backwash cycle.

Example 2

Compared with Example 1, this embodiment reduces the frequency of backwashing and increases the concentration of the agent, mainly including the following steps:

Step 1): Municipal sewage enters the upflow micro-oxygen auto-oxygen-hetero-oxygen granular sludge layer membrane bioreactor, is treated with autotrophic-heterotrophic granular sludge, and then discharges the produced water through the hollow fiber membrane module. Autotrophic-heterotrophic granular sludge contains active functional bacteria composed of ammonium oxidizing bacteria, anammox bacteria and heterotrophic denitrifying bacteria. When the membrane bioreactor is running, the temperature and pH of the membrane bioreactor are controlled to be 30±2°C and 7-8 respectively, the hydraulic retention time (HRT) in the membrane bioreactor is controlled at 10.0h, and the water production rate is 10.9L/ d; Membrane bioreactor is set with internal reflux, the reflux ratio is controlled at 32.3, and the ascending flow rate is controlled at about 3.2m/h; the membrane bioreactor uses an aeration pump for intermittent aeration, the stop aeration ratio: 7min:1min, the aeration volume 0.1L/min, maintain dissolved oxygen at 0.3-0.6mg/L; influent ammonia nitrogen concentration 50mg/L, hollow fiber membrane module material is PVDF, length is 18cm, effective membrane area is 0.075m ² , water flux It is 6.7L/(m ² ·h).

Step 2): Set every 20min of the membrane bioreactor as an online backwashing cycle. In each cycle, first produce water for 18min, and the flux of the produced water is 6.7L/(m ² ·h), then stop the water production, and use the produced water Perform hydraulic backwashing on the hollow fiber membrane module for 1min, the backwashing flux of water is 22.3L/(m ² h), stop the hydraulic backwashing; then perform chemical backwashing on the hollow fiber membrane module for 1min, the backwashing of chemical agents The throughput is 22.3L/(m ² ·h), and the backwashing chemical is 100mg/L NaClO solution. Cycle through the in-line backwash cycle.

Example 3

Compared with Examples 1 and 2, this embodiment further reduces the frequency of backwashing and increases the concentration of the medicament, including the following steps:

Step 1): Municipal sewage enters the upflow micro-aerobic autotrophic-heterotrophic granular sludge layer membrane bioreactor, and after being treated with the autotrophic-heterotrophic granular sludge, the produced water is discharged through the hollow fiber membrane module. Autotrophic-heterotrophic granular sludge contains active functional bacteria composed of ammonium oxidizing bacteria, anammox bacteria and heterotrophic denitrifying bacteria. When the membrane bioreactor is running, the temperature and pH of the membrane bioreactor are controlled to be 30±2°C and 7-8 respectively, the hydraulic retention time (HRT) in the membrane bioreactor is controlled at 9.6h, and the water production is 11.3L /d; the membrane bioreactor is set with internal reflux, the reflux ratio is controlled at 31.2, and the ascending flow rate is controlled at about 3.3m/h; the membrane bioreactor uses an aeration pump for intermittent aeration, and the stop aeration ratio: 6min:1min, aeration The amount of dissolved oxygen is 0.09L/min, and the dissolved oxygen is maintained at 0.3-0.6mg/L; the concentration of ammonia nitrogen in the influent is 50mg/L, the material of the hollow fiber membrane module is PVDF, the length is 18cm, and the effective membrane area is 0.075m ² . The amount is 6.7L/(m ² ·h).

Step 2): Set every 30 minutes of the membrane bioreactor as an online backwashing cycle. In each cycle, water is first produced for 28 minutes, and the water production flux is 6.7L/(m ² ·h). The hollow fiber membrane module is subjected to hydraulic backwashing for 1.2 minutes, and the backwashing flux of water is 22.3L/(m ² ·h). After stopping the hydraulic backwashing, the hollow fiber membrane module is then chemically backwashed for 1.2 minutes. The washing flux is 22.3L/(m ² ·h), and the backwashing agent is 150mg/L NaClO solution. Cycle through the in-line backwash cycle.

Verification example 1

The membrane bioreactors of Examples 1-3 were run for 30 days, during which the system operating efficiency (TN and COD removal efficiency), the activity of autotrophic-heterotrophic granular sludge functional bacteria and the change of transmembrane pressure difference were detected.

The results at the end of run 30d are shown in Figure 1.

Figure 1 shows the total nitrogen (TN) removal rate, COD removal rate and the activity of functional bacteria AerAOB, AnAOB and DNB in the upflow microaerobic autotrophic-heterotrophic granular sludge membrane bioreactor at different backwashing frequencies/concentrations.

As can be seen from Fig. 1, the TN and COD removal rates of embodiment 1 can reach 95.01% and 89.91% respectively; d) and 0.27mgN/(gVSS·d), the activity of each functional bacteria was not affected. The removal rates of TN and COD in Example 2 can reach 94.95% and 89.74% respectively; the activities of functional bacteria AerAOB, AnAOB and DNB are maintained at 0.39mgN/(gVSS·d), 0.41mgN/(gVSS·d) and 0.25mgN /(gVSS·d), which is close to the result of Example 1, and the activity of each functional bacteria is not affected. The removal rates of TN and COD in Example 3 were only 87.98% and 81.41%, respectively, and the activities of functional bacteria AerAOB, AnAOB and DNB were maintained at 0.30mgN/(gVSS·d), 0.32mgN/(gVSS·d) and 0.20mgN /(gVSS·d) left and right, compared with embodiment 1 and 2, each functional bacterium activity of embodiment 3 significantly reduces.

Figure 2 is a diagram of the TMP change of the upflow micro-oxygen auto-oxygen-hetero-oxygen granular sludge membrane bioreactor under different backwashing frequencies/concentrations.

As can be seen from Figure 2, the membrane pressure difference (TMP) of Example 1 increased from 5.02kpa to 5.63kpa, and the membrane fouling rate was 0.02kpa/d.

The transmembrane pressure (TMP) in Example 2 increased from 5.03kpa to 6.23kpa, and the membrane fouling rate was 0.04kpa/d.

The transmembrane pressure difference (TMP) of Example 3 increased from 5.04kpa to 10.26kpa. The membrane fouling rate is 0.17kpa/d.

Among the above three different examples, the transmembrane pressure difference between Example 1 and Example 2 was significantly lower than that of Example 3, and the removal rates of TN and COD both reached more than 90%, and there was no significant difference in the activity of various functional bacteria. Show that the removal effect and microbial activity of TN and COD of embodiment 1 and embodiment 2 are all at a higher level. And in embodiment 3, TN and COD removal rate are only 87.98% and 81.41%, and each functional bacterium activity significantly reduces, and this is mainly because the NaClO concentration used in embodiment 3 is higher, to the microbial production in the membrane bioreactor caused by coercion.

In addition, the backwashing frequency of the membrane bioreactor will directly affect the water production efficiency, because a higher backwashing frequency will reduce the effective water production time, thereby reducing the water production efficiency. Therefore, under the condition of ensuring a similar operating period, the water production rate of Example 2 is higher than that of Example 1.

Verification example 2

The membrane bioreactor of Example 1-3 was operated for 30 days, during which the system for detecting the membrane bioreactor detected the change of the transmembrane pressure difference.

The result shows, embodiment 1-3 under 3 kinds of different backwash frequency/concentration, the system transmembrane pressure difference (being respectively 5.63kpa, 6.23kpa, 10.26kpa) of membrane bioreactor all is lower than that of the membrane bioreactor Off-line chemical cleaning pressure difference limit of the system (50kpa).

In summary, the membrane fouling control method of the membrane bioreactor of the present invention, with the combination of periodic online hydraulic backwash and chemical backwash, as well as the preferred backwash frequency and backwash concentration, can ensure the denitrification of the membrane bioreactor At the same time of carbon removal efficiency, it can also maintain the activity of various functional bacteria. The removal effect of total nitrogen (TN) and COD and microbial activity are at a high level. The transmembrane pressure difference of the membrane bioreactor system is lower than that of off-line chemical cleaning. The difference limit value can completely remove the membrane pollutants of the membrane bioreactor; the membrane pollution control method can effectively solve the membrane fouling problem of the membrane bioreactor, effectively maintain the membrane permeability, and effectively prolong the system operation cycle of the membrane bioreactor , has good engineering application value.

The above description is only a preferred embodiment of the present invention, and is not intended to limit the present invention. Any modification, equivalent replacement or improvement made within the spirit and principles of the present invention shall be included in the protection of the present invention. within range.

Claims (8)

1. A membrane pollution control method of an urban sewage autotrophic-heterotrophic granular sludge MBR denitrification system is characterized in that urban sewage is treated by autotrophic-heterotrophic granular sludge and hollow fiber membrane components to obtain produced water;

carrying out online hydraulic backwashing on the hollow fiber membrane module by using the produced water;

then, carrying out on-line chemical backwashing on the hollow fiber membrane component by using a chemical agent;

and sequentially carrying out the urban sewage treatment, the online hydraulic backwashing and the online chemical backwashing once respectively to form an online backwashing period, wherein the membrane pollution control method is circularly operated for a plurality of online backwashing periods.

2. The membrane pollution control method as claimed in claim 1, wherein the period of the online backwashing is 10-30min, and comprises 8-28min of the treated municipal sewage, 1-1.2min of the online hydraulic backwashing and 1-1.2min of the online chemical backwashing;

the water production flux for treating the urban sewage is 6.7 L.m ^-2 ·h ^-1 ；

The flux of the hydraulic backwashing is 3 to 4 times of the flux of the produced water;

the flux of the chemical backwashing is 3 to 4 times of the flux of the produced water;

the chemical agent for the chemical backwashing is NaClO solution with the concentration of 50-150 mg/L.

3. Use of the membrane fouling control process of claim 1 or 2 in the treatment of municipal wastewater with a membrane bioreactor.

4. The use of claim 3, wherein the membrane bioreactor is an upflow micro-aerobic autotrophic-heterotrophic granular sludge blanket membrane bioreactor; the upflow type micro-aerobic autotrophic-heterotrophic granular sludge layer contains an aeration disc which is connected with an aeration pump and then can be used for intermittent aeration.

5. The use of claim 4, wherein the water is produced by removing carbon from municipal sewage by using an upflow micro-aerobic autotrophic-heterotrophic granular sludge blanket of a membrane bioreactor and then separating granular sludge and organic matter by a hollow fiber membrane module.

6. Use according to claim 4 or 5, wherein the operating conditions of the membrane bioreactor comprise:

controlling the temperature in the membrane bioreactor to be 30 +/-2 ℃ and the pH value to be 7-8;

the hydraulic retention time of the membrane bioreactor is 9.6-11.2h, and the water yield is 9.7-11.3L/d;

controlling the reflux ratio of the membrane bioreactor to be 31.2-36.5, and controlling the ascending flow rate to be 2.6-3.5 m/h;

the membrane bioreactor adopts an aeration pump to carry out intermittent aeration, and the aeration stop ratio of the intermittent aeration is as follows: 5-7min, aeration amount of 0.08-0.10L/min, and dissolved oxygen of 0.3-0.6mg/L.

7. The use according to claim 4, wherein the autotrophic-heterotrophic granular sludge of the upflow microaerophilic autotrophic-heterotrophic granular sludge blanket contains active functional bacteria, wherein the active functional bacteria consist of aerobic ammonia-oxidizing bacteria, anaerobic ammonia-oxidizing bacteria and heterotrophic denitrifying bacteria, and the average particle size of the autotrophic-heterotrophic granular sludge is 1.00-2.00mm.

8. The use according to claim 4, wherein the hollow fiber membrane module is made of PVDF, the transmembrane pressure difference of the hollow fiber membrane module is 5.0-10.5kpa, and the water flux is 6.7L-m ^-2 ·h ^-1 。

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