Pure membrane MBBR (Moving Bed Biofilm Reactor) sewage treatment method

Abstract

The invention discloses a pure membrane MBBR sewage treatment method which is applied to a sewage treatment system. Introducing the sewage into an anoxic denitrification zone, and controlling the sewage to be subjected to amination reaction, organic matter hydrolysis reaction and denitrification reaction with nitrate and nitrite in the anoxic denitrification zone under an anoxic condition; introducing the reacted sewage into an anaerobic ammonia oxidation zone, and enabling the sewage to react with nitrite to generate nitrogen; the sewage treated in the anaerobic ammonia oxidation zone is guided into an aerobic oxidation zone, residual soluble organic matters in the sewage are subjected to a biological oxidation reaction, and residual ammonia nitrogen in the sewage is subjected to a biological nitrification reaction and a short-cut nitrification and denitrification reaction; introducing the sewage treated in the aerobic oxidation zone into a high-density settling zone, and carrying out a second hydrolysis reaction on residual refractory organic matters in the sewage; the sewage treated in the high-density settling zone is finally guided into an MBBR biological filtration zone, so that total phosphorus and suspended solids in the sewage are separated.

Description

Technical Field

[0001] The present application relates to the field of sewage treatment, and in particular to a pure membrane MBBR sewage treatment method. Background Art

[0002] The AO process is the earliest traditional activated sludge process developed by humans to treat sewage. It can effectively remove organic matter from sewage, is simple to operate, and has low cost. It is deeply loved by water treatment manufacturers at home and abroad. However, with economic development, the phenomenon of eutrophication of water bodies has become more and more serious, and the impact on the environment has become more and more obvious. Therefore, phosphorus removal and nitrogen removal are also listed as the goals of sewage treatment.

[0003] In the traditional AO process, during the anoxic stage, denitrifying bacteria use nitrates or nitrites as electron acceptors to convert organic matter into nitrogen and water. This process requires sufficient carbon sources to support the growth and metabolic activities of microorganisms. If the carbon source is insufficient, the denitrification reaction will be affected, resulting in reduced denitrification efficiency.

[0004] Anaerobic ammonium oxidizing bacteria (AnAOB) is a unique microorganism that can use carbon dioxide or carbonate as a carbon source, ammonium salt as an electron donor, and nitrite or nitrate as an acceptor under anaerobic conditions to convert ammonia nitrogen in sewage into nitrogen gas for removal through biochemical methods. However, the growth rate of anaerobic ammonium oxidizing bacteria (AnAOB) is extremely slow, which limits the large-scale application of anaerobic ammonium oxidation technology. Summary of the invention

[0005] The present application provides a pure membrane MBBR sewage treatment method. The method is applied to a sewage treatment system, which includes: an anoxic denitrification zone, an anaerobic ammonia oxidation zone, an aerobic oxidation zone, a high-density sedimentation zone, and an MBBR biological filtration zone;

[0006] The sewage is introduced into the anoxic denitrification zone, and the sewage is controlled to undergo amination reaction, organic matter hydrolysis reaction and denitrification reaction with nitrate and nitrite in the anoxic denitrification zone under anoxic conditions;

[0007] introducing the reacted sewage into the anaerobic ammonium oxidation zone to react the sewage with nitrite to generate nitrogen;

[0008] The sewage treated in the anaerobic ammonium oxidation zone is introduced into the aerobic oxidation zone to cause the remaining dissolved organic matter in the sewage to undergo biological oxidation reaction, and the remaining ammonia nitrogen in the sewage to undergo biological nitrification reaction and short-range nitrification and denitrification reaction;

[0009] The sewage treated in the aerobic oxidation zone is introduced into the high-density sedimentation zone to separate the total phosphorus and suspended solids in the sewage;

[0010] The sewage treated in the high-density sedimentation area is finally introduced into the MBBR biological filtration area to filter the sewage.

[0011] Optionally, the amination reaction includes: converting organic nitrogen in the sewage into ammonia nitrogen;

[0012] The hydrolysis reaction of organic matter includes: decomposing macromolecular organic matter in sewage into small molecular fatty acids that can be used by denitrifying bacteria;

[0013] The denitrification reaction includes: converting small molecular fatty acids produced by the hydrolysis reaction and nitrates and nitrites in the anoxic denitrification zone into nitrogen gas.

[0014] Optionally, the aerobic oxidation zone is provided with a nitrification reflow facility, and the nitrified liquid in the aerobic oxidation zone is reflowed to the anoxic denitrification zone and the anaerobic ammonia oxidation zone through the nitrification reflow facility.

[0015] Optionally, the high-density sedimentation zone is provided with a coagulation zone, a flocculation zone and a separation zone;

[0016] The coagulation zone is used to add a coagulant into the sewage so that the coagulant reacts with the sewage to obtain small flocs;

[0017] The flocculation zone is used to accelerate the stirring of the small flocs to obtain large floc particles;

[0018] The separation zone is used to accelerate the sedimentation of the large floc particles to obtain sludge and supernatant.

[0019] Optionally, a sludge treatment system is provided in the MBBR biological filtration area; the sludge generated after filtration in the MBBR biological filtration area is discharged to the sludge treatment system, and the sludge treatment system performs drying treatment on the sludge.

[0020] Optionally, MBBR biological fillers are added to both the anoxic denitrification zone and the anaerobic ammonium oxidation zone, and the MBBR biological fillers serve as attachment beds for the growth and reproduction of anaerobic ammonium oxidizing bacteria and nitrifying bacteria.

[0021] Optionally, the proportion of the MBBR biological filler added is 55% to 75%.

[0022] Optionally, the aerobic oxidation zone includes an aeration zone, and the aeration zone is provided with a removable belt aerator, and the removable belt aerator is used to provide oxygen.

[0023] It can be seen from the above technical solutions that this application has the following advantages:

[0024] 1. This application can greatly reduce the dependence of anaerobic ammonia-oxidizing bacteria on carbon sources during the denitrification and phosphorus removal process, and achieve effective removal of nitrogen and phosphorus in sewage, so that the total hydraulic retention time (HRT) of the system is less than 11h.

[0025] 2. Separate the denitrification and anaerobic ammonium oxidation denitrification processes, that is, complete the removal of soluble small molecular fatty acids in the water body through the anoxic denitrification zone, and then limit the growth of denitrifying bacteria and other heterotrophic bacteria in the anaerobic ammonium oxidation zone to promote the growth of anaerobic ammonium oxidizing bacteria, making anaerobic ammonium oxidizing bacteria the dominant species in the competition.

[0026] 3. In the sewage treatment system, a nitrification reflux system is set up to avoid or reduce the inhibitory or competitive effects of a small amount of microorganisms in the nitrification reflux liquid on the fixed bacterial flora in each area through nitrification reflux facilities. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solution in the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0028] Figure 1 This is a schematic diagram of the process of Example 1 of the pure membrane MBBR sewage treatment method provided in this application;

[0029] Figure 2 A schematic diagram of the structure of the sewage treatment system provided for this application;

[0030] Figure 3 This is a schematic diagram of the process flow of Example 2 of the pure membrane MBBR wastewater treatment method provided in this application. DETAILED DESCRIPTION

[0031] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0032] For example, see Figure 1 and Figure 2 , the present application provides a pure membrane MBBR sewage treatment method. The method is applied to a sewage treatment system, the sewage treatment system includes: anoxic denitrification zone, anaerobic ammonia oxidation zone, aerobic oxidation zone, high-density sedimentation zone and MBBR biological filtration zone;

[0033] S101, introducing the sewage into the anoxic denitrification zone, and controlling the sewage to undergo amination reaction, organic matter hydrolysis reaction and denitrification reaction with nitrate and nitrite in the anoxic denitrification zone under anoxic conditions;

[0034] The anoxic denitrification zone is an area where microorganisms are used to remove nitrogen pollutants from water. Sewage containing high concentrations of ammonia nitrogen is introduced into the anoxic denitrification zone through pipes, making the anoxic denitrification zone in anoxic state. Under anaerobic conditions, organic nitrogen compounds in sewage, such as proteins and amino acids, are decomposed into ammonia by microorganisms, which is called amination reaction. Complex organic matter in sewage is hydrolyzed into organic acids and alcohols under the action of microorganisms, which is called organic matter hydrolysis reaction.

[0035] Denitrifying bacteria are widely distributed in anoxic environments such as soil, water bodies, and sewage treatment systems. Under anoxic conditions, nitrates and nitrites in the anoxic denitrification zone are reduced to nitrogen gas by denitrifying bacteria, which is the denitrification reaction. Under anoxic conditions, denitrifying bacteria are used to reduce nitrates to nitrogen gas, achieving effective nitrogen removal, thereby reducing the nitrogen content in the water body and alleviating eutrophication.

[0036] S102, introducing the reacted sewage into the anaerobic ammonium oxidation zone to react the sewage with nitrite to generate nitrogen;

[0037] The organic matter that is difficult to be utilized by organisms in the anoxic denitrification zone and the ammonia nitrogen produced by the amination reaction enter the anaerobic ammonium oxidation zone. The anaerobic ammonium oxidation zone is a zone where anaerobic ammonium oxidation denitrification is completed under anaerobic conditions using ammonia as the electron donor and nitrite as the electron acceptor through anaerobic ammonium oxidizing bacteria.

[0038] The anaerobic ammonium oxidation zone mainly carries out anaerobic ammonium oxidation reaction. Under anaerobic conditions, the ammonia nitrogen in the sewage reacts with nitrite to generate nitrogen gas through the action of anaerobic ammonium oxidizing bacteria. The following is the chemical reaction equation of ammonia nitrogen and nitrite.

[0039] NH 3 +HNO 2 →N 2 +2H 2 O

[0040] In order to promote the growth of anaerobic ammonium oxidizing bacteria and nitrifying bacteria, MBBR biological fillers are added in the anoxic denitrification zone and the anaerobic ammonium oxidation zone. The MBBR biological fillers serve as attachment beds for the growth and reproduction of anaerobic ammonium oxidizing bacteria and nitrifying bacteria. The proportion of MBBR biological fillers added is 55% to 75%.

[0041] MBBR biological filler is a carrier that provides an environment for microorganisms to attach and grow. It is made of polymer materials, such as polyethylene, polypropylene and their modified materials, so that microorganisms can form biofilms on it, thereby promoting the degradation and transformation of pollutants. The addition of MBBR biological filler not only provides a place for microorganisms to attach, but also promotes the denitrification reaction, thereby improving the denitrification efficiency of the sewage treatment system.

[0042] S103, introducing the sewage treated in the anaerobic ammonium oxidation zone into the aerobic oxidation zone, so that the remaining dissolved organic matter in the sewage undergoes a biological oxidation reaction, and the remaining ammonia nitrogen in the sewage undergoes a biological nitrification reaction and a short-range nitrification and denitrification reaction;

[0043] Ammonia nitrogen in the sewage is initially removed through the denitrification zone and the anaerobic ammonium oxidation reaction zone, and the sewage containing nitrate, nitrite and soluble small molecular organic matter enters the aerobic oxidation zone. In the aerobic oxidation zone, sufficient oxygen can promote the degradation of organic matter by microorganisms and the further conversion of ammonia nitrogen.

[0044] Biological oxidation reaction is that aerobic microorganisms use oxygen as an electron acceptor to oxidize organic matter into carbon dioxide and water, while releasing energy for their own growth and metabolism. In this process, organic matter is completely decomposed, reducing the organic matter in the sewage; biological nitrification reaction is that under aerobic conditions, ammonia oxidizing bacteria oxidize ammonia nitrogen into nitrite, and then nitrifying bacteria further oxidize nitrite into nitrate; short-term nitrification and denitrification reaction is when the biological nitrification reaction reaches the stage of oxidizing ammonia nitrogen into nitrite, denitrifying bacteria use organic matter as electron donors to reduce nitrite to nitrogen gas and release it into the atmosphere. Short-term nitrification and denitrification reaction can effectively reduce carbon source consumption and sludge production.

[0045] The aerobic oxidation zone is equipped with a nitrification reflow facility. The nitrification liquid in the aerobic oxidation zone is returned to the anoxic denitrification zone through the nitrification reflow facility. The returned nitrification liquid contains a large amount of nitrate and nitrite. In the anoxic denitrification zone, anaerobic ammonia-oxidizing bacteria use nitrate or nitrite as electron acceptors to convert ammonia nitrogen into nitrogen gas, thereby achieving efficient denitrification effect.

[0046] The aerobic oxidation zone includes an aeration zone, which is equipped with a removable belt aerator. The removable belt aerator provides oxygen for the aerobic oxidation zone to meet the growth and metabolic needs of aerobic microorganisms, thereby promoting the degradation of organic pollutants. Aeration is performed using a half-removable hose circulation aeration method, in which the rising buoyancy of air bubbles drives the filler and the surrounding water to flow. When the airflow passes through the gap between the water flow and the filler, it is blocked by the filler and divided into small bubbles. This process increases the contact area between the biofilm and oxygen and the oxygen transfer efficiency, thereby improving the effect of sewage treatment.

[0047] S104, introducing the sewage treated in the aerobic oxidation zone into the high-density sedimentation zone to separate the total phosphorus and suspended solids in the sewage;

[0048] The high-density sedimentation tank mainly utilizes the difference in specific gravity of substances to allow suspended matter to settle to the bottom through gravity, thereby achieving water purification.

[0049] The high-density sedimentation area is provided with a coagulation area, a flocculation area and a separation area; the coagulation area is used to add a coagulant to the sewage so that the coagulant reacts with the sewage to obtain small flocs; the flocculation area is used to accelerate the stirring of the small flocs to obtain large floc particles; the separation area is used to accelerate the sedimentation of the large floc particles to obtain sludge and supernatant. When a coagulant is added to the sewage, the coagulant forms larger flocs by chemically reacting with the suspended matter and colloidal particles in the sewage. These flocs are easy to settle, thereby achieving efficient separation of suspended matter. When a dephosphorization agent is added to the sewage, the dephosphorization agent converts phosphates in the sewage into precipitates through a chemical precipitation reaction, thereby removing total phosphorus.

[0050] The high-density sedimentation area is equipped with a sludge treatment system, which dries the sludge, such as sludge concentration and dehydration, to reduce the volume and weight of the sludge for easy storage and transportation. For sludge that cannot be used, it can be incinerated for harmless treatment.

[0051] S105, the sewage treated in the high-density sedimentation area is finally introduced into the MBBR biological filtration area to filter the sewage.

[0052] The MBBR biological filtration area is equipped with a deep filtration system; the sewage treated in the high-density sedimentation area enters the MBBR biological filtration area, which is equipped with MBBR filter materials, which are used to provide a growth environment for microorganisms to reproduce. The MBBR biological filtration area is equipped with a deep filtration system to filter the separated clean water, disinfect and test the filtered clean water, and then discharge it after the test meets the standards.

[0053] In this embodiment, the pure membrane MBBR sewage treatment method is applied to the sewage treatment system. The pure membrane MBBR sewage treatment method can greatly reduce the dependence of the denitrification process on the carbon source, and realize the effective removal of nitrogen and phosphorus in sewage, so that the total hydraulic retention time (HRT) of the system is less than 11h. The denitrification denitrification is separated from the anaerobic ammonia oxidation denitrification process, that is, the removal of soluble small molecular fatty acids in the water body is completed through the anoxic denitrification zone, and then the growth of denitrifying bacteria and other heterotrophic bacteria is restricted in the anaerobic ammonia oxidation zone to promote the growth of anaerobic ammonia oxidizing bacteria, so that anaerobic ammonia oxidizing bacteria become the dominant species in the competition. In the sewage treatment system, a nitrification reflux facility is set up to avoid or reduce the inhibitory or competitive effects of a small amount of microorganisms in the nitrification reflux liquid on the fixed bacterial flora in each area.

[0054] For example 2, please refer to Figure 2 In the anoxic denitrification zone, amination reaction, organic matter hydrolysis reaction and denitrification reaction are mainly carried out. The following is a detailed description of the three reactions:

[0055] S201, performing an amination reaction in the anoxic denitrification zone, the amination reaction comprising: converting organic nitrogen in the sewage into ammonia nitrogen;

[0056] In the anoxic denitrification zone, the amination reaction converts nitrogen-containing organic matter into ammonia nitrogen under the action of microorganisms. In this process, organic nitrogen compounds are decomposed by microorganisms, releasing ammonia nitrogen and other products, such as carbon dioxide and water, which provide the necessary ammonia nitrogen substrate for the subsequent denitrification reaction.

[0057] S202, performing an organic matter hydrolysis reaction in the anoxic denitrification zone, wherein the organic matter hydrolysis reaction includes: decomposing macromolecular organic matter in the sewage into small molecular fatty acids that can be utilized by denitrifying bacteria;

[0058] In sewage treatment, hydrolysis reactions decompose macromolecular organic matter in sewage into small molecular fatty acids that can be used by denitrifying bacteria. For example, fatty acid esters are decomposed into fatty acids and glycerol under the action of microbial enzymes.

[0059] Through the hydrolysis reaction of organic matter, large molecular organic matter is decomposed into small molecular fatty acids, preparing for the denitrification reaction, thereby improving the removal effect of nitrogen pollutants.

[0060] S203. Performing a denitrification reaction in the anoxic denitrification zone. The denitrification reaction includes: converting small molecular fatty acids produced by the hydrolysis reaction and nitrates and nitrites in the anoxic denitrification zone into nitrogen gas.

[0061] Denitrification reaction includes the reduction of nitrate and nitrite.

[0062] The reduction of nitrate is the process by which denitrifying bacteria use nitrate as an electron acceptor. Taking methanol as an electron donor, for example, nitrate is reduced to nitrite. The reaction equation is as follows:

[0063] 3NO 3 - +CH 3 OH→3NO 2 - +2H 2 O+CO 2

[0064] The reduction of nitrite, under anaerobic conditions, uses nitrite as an electron acceptor and hydrogen ions as proton donors. Taking methanol as an electron donor as an example, nitrite is reduced to nitrogen gas. The reaction equation is as follows:

[0065] 2H + +2NO 2 - +CH 3 OH→N 2 +3H 2 O+CO 2

[0066] S204, introducing the reacted sewage into the anaerobic ammonium oxidation zone to react the sewage with nitrite to generate nitrogen;

[0067] S205, introducing the sewage treated in the anaerobic ammonium oxidation zone into the aerobic oxidation zone, so that the remaining dissolved organic matter in the sewage undergoes a biological oxidation reaction, and the remaining ammonia nitrogen in the sewage undergoes a biological nitrification reaction and a short-range nitrification and denitrification reaction;

[0068] S206, introducing the sewage treated in the aerobic oxidation zone into the high-density sedimentation zone to separate the total phosphorus and suspended solids in the sewage;

[0069] S207, the sewage treated in the high-density sedimentation area is finally introduced into the MBBR biological filtration area to filter the sewage.

[0070] In this embodiment, steps S204 to S207 are similar to steps S102 to S105 of the aforementioned embodiment, and are not described again here.

[0071] In this embodiment, the denitrification zone undergoes amination reaction, organic matter hydrolysis reaction and denitrification reaction. The amination reaction provides the necessary ammonia nitrogen substrate for the subsequent nitrification and denitrification reactions, and the organic matter hydrolysis reaction provides available small molecule fatty acids for denitrifying bacteria. The denitrification reaction mainly reduces nitrate and nitrite in the water to nitrogen gas, thereby removing nitrogen pollutants in the water.

Claims

1. A pure membrane MBBR sewage treatment method, characterized in that: The method is applied to a sewage treatment system, which comprises: an anoxic denitrification zone, an anaerobic ammonium oxidation zone, an aerobic oxidation zone, a high-density sedimentation zone and an MBBR biological filtration zone; The sewage is introduced into the anoxic denitrification zone, and the sewage is controlled to undergo amination reaction, organic matter hydrolysis reaction and denitrification reaction with nitrate and nitrite in the anoxic denitrification zone under anoxic conditions; introducing the reacted sewage into the anaerobic ammonium oxidation zone to react the sewage with nitrite to generate nitrogen; The sewage treated in the anaerobic ammonium oxidation zone is introduced into the aerobic oxidation zone to cause the remaining dissolved organic matter in the sewage to undergo biological oxidation reaction, and the remaining ammonia nitrogen in the sewage to undergo biological nitrification reaction and short-range nitrification and denitrification reaction; The sewage treated in the aerobic oxidation zone is introduced into the high-density sedimentation zone to separate the total phosphorus and suspended solids in the sewage; The sewage treated in the high-density sedimentation area is finally introduced into the MBBR biological filtration area to filter the sewage.

2. The pure membrane MBBR sewage treatment method according to claim 1, characterized in that ； The amination reaction comprises: converting organic nitrogen in sewage into ammonia nitrogen; The hydrolysis reaction of organic matter includes: decomposing macromolecular organic matter in sewage into small molecular fatty acids that can be used by denitrifying bacteria; The denitrification reaction includes: converting small molecular fatty acids produced by the hydrolysis reaction and nitrates and nitrites in the anoxic denitrification zone into nitrogen gas.

3. The pure membrane MBBR sewage treatment method according to claim 1, characterized in that: The aerobic oxidation zone is provided with a nitrification reflow facility, and the nitrified liquid in the aerobic oxidation zone is reflowed to the anoxic denitrification zone through the nitrification reflow facility.

4. The pure membrane MBBR sewage treatment method according to claim 1, characterized in that: The high-density sedimentation zone is provided with a coagulation zone, a flocculation zone and a separation zone; The coagulation zone is used to add a coagulant into the sewage so that the coagulant reacts with the sewage to obtain small flocs; The flocculation zone is used to accelerate the stirring of the small flocs to obtain large floc particles; The separation zone is used to accelerate the sedimentation of the large floc particles to obtain sludge and supernatant.

5. The pure membrane MBBR sewage treatment method according to claim 1, characterized in that: The high-density sedimentation area is provided with a sludge treatment system; the sludge treatment system performs drying treatment on the sludge.

6. The pure membrane MBBR sewage treatment method according to claim 1, characterized in that: MBBR biological fillers are added into the anoxic denitrification zone and the anaerobic ammonium oxidation zone, and the MBBR biological fillers serve as attachment beds for the growth and reproduction of anaerobic ammonium oxidizing bacteria and nitrifying bacteria.

7. The pure membrane MBBR sewage treatment method according to claim 6, characterized in that: The proportion of the MBBR biological filler added is 55% to 75%.

8. The pure membrane MBBR sewage treatment method according to claim 1, characterized in that: The aerobic oxidation zone includes an aeration zone, and the aeration zone is provided with a removable belt aerator, and the removable belt aerator is used to provide oxygen.

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