KR100926268B1 - Process and apparatus of four stages biological treatment including combination of pre oxic and post denitrification through none driven internal recycles and submerged membrane filtration for treating sewage and waste water - Google Patents

Abstract

PURPOSE: A wastewater processing method and device thereof are provided to reduce processing cost, and to improve removing efficiency of organic compounds, suspended materials, nitrogen and phosphorus while increasing nitrification and denitrification efficiency. CONSTITUTION: A wastewater processing device using biological and submerged membrane filtering comprises an anaerobic process bath(20), a pre-aerobic bath(30), a post-anoxic processing bath(40), a transfer pump facility, a flow rate shock-absorbing distribution tank(60), an aerobic submerged membrane bath(50), a separation membrane device, a residual sludge pulling pump(160), a first transfer line(80), and a second transfer line(90). The anaerobic process bath includes a mixer(100). The separation membrane unit includes a separation unit(130) having a plurality of separation membrane modules and a filtering pump(150). The residual sludge pulling pump removes the absorbed phosphorus while maintaining concentration of microbial mixed liquor. The first transfer line transfers a part of the microbial mixed liquor to the pre-aerobic bath, and the second transfer line transfers a part of the microbial mixed liquor to the anaerobic process bath.

Description

Wastewater treatment method and apparatus using biological treatment and immersion membrane filtration and its apparatus

The present invention relates to a method for treating sewage and wastewater using biological treatment and submerged membrane filtration, and more particularly, to an anaerobic treatment tank, an aerobic treatment tank, and an anaerobic treatment tank for sewage, sewage, or wastewater pretreated through a fine screen. After passing through the treatment tank and the aerobic immersion membrane tank, it is pumped from the oxygen-free treatment tank to the flow buffer distribution tank at the front of the aerobic separation membrane immersion tank for internal transport, and then flows directly from the flow buffer distribution tank to the anaerobic treatment tank by water level difference. The solid-liquid separation of the biological treatment process which flows into the aerobic immersion membrane tank from the conveying line and the flow buffer distribution tank into natural flow and then conveys it back to the pre-exposure treatment tank by force level difference and the microbial mixed solution which has undergone such biological treatment process by the separation membrane MBR (Membrane BioReactor) process combined with membrane separation process A method and apparatus for removing nitrogen and phosphorus with high efficiency.

     The conventional treatment of sewage water is a biological treatment process, which includes an anaerobic process in which phosphorus release reaction is carried out from activated sludge returned from a sedimentation basin, an anoxic process in which denitrification occurs, and an aerobic process in which nitrification and organic matter decomposition and phosphorus excess intake occur. Anaerobic Anoxic Oxic Process has been commonly used.

     However, these processes have a problem related to the sedimentation of microorganisms during operation, which causes deterioration of flocculation and deterioration of bulking or foaming, which leads to loss of microorganisms in sedimentation tanks, resulting in poor water quality. As a result, the concentration of microorganisms in the reactor was reduced, resulting in a decrease in treatment efficiency.

     In recent years, the interest and desire for water quality and environment are gradually increasing with the improvement of living standard, and considering the recent trend that the effluent water quality standards are gradually being strengthened, In recent years, the introduction of new technologies, such as the MBR process that enables a stable treatment is increasing.

     In the first stage introduction stage (from the beginning of 1990), the membrane is simply added to the general activated sludge process without the nitrogen removal process. In the second stage of diffusion (since 1993), an oxygen-free tank for nitrogen removal was adopted, and the two stages were changed from a single reactor to two reactors. The trend is changing from dogs to three and lowering the SRT to 25-40 days.

     As a result, the global market is recognized for its efficiency, stability, and reliability in terms of efficiency, stability, and reliability. In addition, the membrane is immersed in a bioreactor for suction filtration. There is a tendency to change into a removable multistage reactor type.

     In addition, MBR process requires a large amount of aeration to maintain high microbial mixture, which generates high energy cost because it forms low mixing condition by high microbial concentration and eventually leads to poor oxygen transfer. To this end, there is a need for an optimization method of the abandonment method.

On the other hand, the MBR process is not high biological dephosphorization efficiency due to the maintenance of relatively high microbial concentration and high sludge age, so to overcome this through chemical aggregation.

       The present invention has been made to solve the conventional problems as described above, the object of the present invention is to provide a reaction tank configuration and conveying method, such as to efficiently use the air volume compared to the existing MBR process for the advanced treatment of sewage, sewage and wastewater The MBR process combines biological treatment process and membrane filtration process to optimize the nitrification and denitrification efficiency, and can significantly improve the removal rate of organic matter, suspended solids, phosphorus as well as nitrogen removal rate. The present invention provides a method and apparatus for treating sewage and sewage that can reduce costs in terms of economics.

       In order to achieve the above object, the present invention,

      (A) introducing a substantial portion (about 80%) of wastewater, pretreated by a microscreen, into an anaerobic treatment tank to maximize the release of phosphorus in the microbial mixture;

      (B) In order to optimize the nitrification of the microbial mixture returned internally to natural oil in the aerobic submerged membrane tank at the next stage, the tanks are divided into 3 to 4 tanks. Improving nitrification efficiency under aerobic conditions;

      (C) denitrifying the nitrified microbial mixture conveyed internally through a preliminary aerobic treatment tank and a previous aerobic immersion tank and a preliminary aerobic treatment tank under a pretreated, a portion (about 20%) of waste water;

      (D) after the denitrification step, waste water is treated aerobicly in an aerobic immersion membrane tank to induce residual organic matter decomposition and nitrification, and then the nitrified microbial mixture at a predetermined ratio in the water level difference in the step (B). Internal conveyance by natural flow of water; And

      (E) solid-liquid separation of the microbial mixed solution passed through the step (D) by a membrane module to produce treated water;

     (F) Phosphorus ingested in the microbial mixture in the anaerobic treatment tank, preaerobic treatment tank, after anaerobic treatment tank, and aerobic immersion membrane tank in the front end is included in the excess sludge discharged to maintain the concentration of the microbial mixture in the whole treatment process. Removing phosphorus by discharging it from the tank;

      (G) The microbial mixed solution passed through step (C) is transferred to a flow buffer distribution tank located at the upper end of the aerobic immersion tank using a pump, and the flow rate at a predetermined bar rate (about 0.5 to 1.0 times the inflow amount). ) Is distributed and returned to the anaerobic treatment tank as natural flow, and another predetermined ratio of flow rate (about 2 to 4 times the amount of inflow) is distributed to the aerobic immersion membrane tank, characterized by the wastewater treatment method.

       In addition, the present invention,

      (A) anaerobic treatment tank equipped with a stirrer for maximizing the discharge of phosphorus in the waste water, pretreated by a fine screen;

      (B) a pre-treatment treatment tank equipped with an acid system to induce decomposition and nitrification of organic matter divided into three to four tanks to improve the nitrification efficiency and control the air volume;

      (C) a post-oxygen treatment tank equipped with a stirrer for denitrifying the waste water flowing down;

      (D) pump transfer equipment to the aerobic immersion membrane tank in consideration of the internal transport amount and the treated water amount in the post-oxygen treatment tank described above;

      (E) through the buffer and distribution of the flow rate transferred from the anaerobic tank, the predetermined flow rate is conveyed to the anaerobic treatment tank under natural flow, and the predetermined flow rate is a flow buffer distribution tank to flow into the aerobic immersion membrane tank;

      (F) an aerobic immersion membrane tank which induces organic decomposition and nitrification by aerobic treatment of wastewater introduced from the flow buffer distribution tank;

      (G) a membrane device including a membrane unit including a plurality of membrane modules for solid-liquid separation of the microbial mixture from the aerobic immersion membrane tank and a filtration pump;

      (H) the excess sludge discharge pump device for maintaining the concentration of the microorganism mixture in the treatment process and remove the phosphorus absorbed in the aerobic immersion membrane tank;

(I) a part of the nitrified microbial mixture treated in the second conveying line and the aerobic immersion membrane tank for returning a part of the microbial mixture solution from the flow rate buffer tank to the anaerobic treatment tank to the natural oil tank. A waste water treatment apparatus comprising a first conveying line for conveying is characterized by the above-mentioned.

      As described above, the wastewater treatment method and apparatus according to the present invention divides the aerobic tank into three to four to control the amount of air required for each to secure an optimum nitrification rate and to supply the amount of air necessary for loading in place. By eliminating heterogeneous oxygen distribution in the aerobic tank, which is a problem in the MBR process, and reducing unnecessary air supply, it is possible to maintain a high concentration of microorganisms in the reaction tank by producing treated water using a membrane. Its capacity can be optimized to reduce the site due to the compactness of sewage and wastewater treatment systems, and to ensure stable treatment efficiency even under high load conditions, and to reduce the production of sludge. The preaerobic treatment tank, the anaerobic oxygen treatment tank and the aerobic immersion membrane tank By performing internal transfer from the aerobic immersion membrane tank to the aerobic treatment tank than the general anaerobic treatment tank, the anaerobic treatment tank, the aerobic treatment tank and the aerobic immersion tank, the nitrification rate can be increased and the denitrification rate can be improved. After one pump transfer from the anaerobic treatment tank to the aerobic immersion membrane tank, the internal transfer of the anaerobic treatment tank and the aerobic treatment tank through the aerobic treatment tank is made possible by natural flow, thereby reducing the equipment and maintenance costs. Most of the coliforms are removed by the separation membrane applied to the cough membrane tank, and the treated water quality is good, so that the treated water can be reused without a separate tertiary treatment.

Process reactor configuration

      In general, in the MBR process, due to the high microbial mixture, the mixing in the aerobic tank is often poor. As a result, the oxygen transfer rate is lowered, which makes it difficult to secure the required dissolved oxygen concentration and requires more air than necessary.

       Therefore, in the present invention, in order to develop an advanced treatment process of wastewater, which can solve this problem, a general high-treatment type MBR process consisting of existing general anaerobic treatment tank, anoxic treatment tank, aerobic treatment tank, and aerobic immersion membrane tank (FIG. 2) Anaerobic treatment tank, pre-aerobic treatment tank, after-oxygen treatment tank and aerobic immersion membrane tank prepared for this (Fig. 1) were studied through an experimental apparatus of an appropriate scale.

      According to the experimental results, the results of the investigation of the achievement of the nitrification rate of the aerobic treatment tank and the aerobic immersion membrane tank in the conventional general MBR process (Fig. 2), respectively, appeared as 53.5% and 46.5%. Based on this, the amount of air supplied for nitrification is governed by the efficiency of the diffuser. When examining the efficiency of the diffuser of the aerobic treatment tank and the aerobic submerged membrane tank, the aerobic treatment of the aerobic treatment tank can be applied variously, so While there is no problem in supplying the air, the air supply of the aerobic immersion tank depends on the diffuser installed at the bottom of the membrane unit, and it is composed of a structure having a relatively low oxygen transfer rate. Not only that, but a large amount of air must be additionally supplied, too much air can adversely affect the membrane module.

      Therefore, in order to solve this, the experiment was performed by the anaerobic treatment tank, the preaerobic treatment tank, the post anaerobic treatment tank, and the aerobic immersion membrane tank (FIG. 1). Joe's nitrification rate was divided into 83.7% and 16.3%, respectively.

      By such experiments, it can be seen that the method of the present invention can more efficiently supply the required air amount, as well as minimize the influence on the membrane module and excessive air supply.

       In order to secure a predetermined nitrification efficiency in the preaerobic treatment tank and to distribute the amount of air appropriately, the preaerobic treatment tank was divided into three equal volumes in three steps for the process of the present invention (Fig. 1). The nitrification rate at each stage of the preaerobic treatment tank was 70.6%, 23.5%, and 5.9%, respectively, indicating that most nitrification occurred in the first two divisions. The device should be configured for differential supply.

       Hereinafter, the present invention will be described with reference to the accompanying drawings in conjunction with the accompanying drawings, the present invention is the same as the following examples, but is not limited to the following examples.

Example 1

1. Experiment apparatus

     The present inventors, as shown in Figure 1, the inflow water through the pre-treatment facility for the MBR treatment process through the raw water inlet pipe 10, anaerobic treatment tank 20, preaerobic treatment tank 30, after anaerobic treatment tank ( 40) and aerobic immersion membrane tank (50) was carried out for 6 months of treatment efficiency experiment.

     This experimental device is divided into raw water distribution tank, treatment process MBR tank, each treatment tank and operation control panel (PLC panel), flow buffering tank (60), first conveying line (80), second conveying line (90), flow rate Flow meter 170, differential pressure gauge 190, air cleaning blower (for aeration, including control valve 180, suction pump (membrane filtration pump 150, sludge drawing pump 160, microbial mixed solution transfer pump 200)) Blower 120, separator blower 140), flow meter 170, preaerobic treatment tank diffuser 110, anaerobic treatment tank 20 and post-oxygen treatment tank 40, agitator 100 and membrane unit 130 and the like.

     The raw water used in this experiment was raw water from 00 sewage treatment plant, the treatment capacity was 200L / day, and the total residence time of the reaction tank was 8.0 hours, 0.7 hours for anaerobic treatment tank (20), 2.5 hours for preaerobic treatment tank (30). After, the oxygen free treatment tank 40 3.0 hours, the aerobic immersion membrane tank 1.8 hours, and the internal transport amount of the first transfer line 80 is 2.5Q and the second transfer line 90 was 0.7Q. The experimental flat membrane was immersed in the aerobic immersion membrane tank and quantitative suction filtration was performed and the operation cycle was 10 minutes of filtration and 2 minutes of rest. The filtration flux was operated at about 25 l / hr.

The average properties of the raw water used in the process according to this experiment were BOD 126.6mg / L, COD _Mn 104.5mg / L, SS 143.0mg / L, TN 31.9mg / L, TP 3.5mg / L.

   Microbial concentration of bioreactor was slightly different for each reactor, but 5,467 ~ 7,890 (average 6,398) mg / L, water temperature was 20.1 ~ 26.8 (average 22.8), and average sludge retention time (SRT) ) Was about 23 days.

2. Evaluation

1) Evaluation of Biological Treatment Performance

      The results of the treatment of the present invention MBR process for the influent water is shown in Table 1 below.

      Table 1

      Performance Evaluation of Biological Treatments of the Invention

Item Influent sewage (mg / L) Result of treatment with the method of the present invention (mg / L) Removal efficiency Concentration range Average Average (%) BOD 111.4-146.5 126.6 1.4 98.9 COD _Mn 89.1 ~ 113.2 104.5 6.0 94.3 SS 129.5-156.6 143.0 0.2 99.9 T-N 28.5-37.6 31.9 8.1 74.7 T-P 2.5 ~ 4.5 3.5 1.1 68.7

As can be seen from the above table, the removal rate of BOD and SS was stable and high efficiency of 98.9 and 99.9%, respectively, and the removal efficiency is similar to that of the general sewage MBR process, but the COD _Mn removal rate is 94.3. The percentage was somewhat higher, which is related to complete solids removal by the membrane.

      The treated water of T-N is 6.2 ~ 10.2 (average 8.1) mg / L, which shows stable treatment efficiency, which is presumably due to the stable operation that can sufficiently maintain nitrification and denitrification microorganisms through the membrane with the introduction of MBR process.

      The T-P removal rate is about 68.7%, which is presumed to be the effect of the SRT (Sludge Retention Time), which operated somewhat higher.

      Inflow water quality and treatment water quality for BOD, T-N, and T-P are shown to be high with stable treatment efficiency as shown in the following graphs in FIGS. 4, 5, and 6.

2) Performance Evaluation of Membrane Separation Process

     As can be seen from the graph shown in Fig. 7, the flux range per unit area was about 25 L / m 2, and the transmembrane pressure was about 0.24 bar and relatively stable operation was performed. There was also a small amount of contaminants, which was a problem with the mask, and the drug was not cleaned.

     In the process of the present invention, the nitrified microbial mixture from the aerobic immersion membrane tank 50 is internally transported to the preaerobic treatment tank 30 of the front end through the first conveying line 80 at a predetermined ratio and then the preaerobic treatment tank ( After nitrifying once again in 30), it is introduced into the after anoxic treatment tank 40, and the denitrified microorganism mixture sufficiently depleted in the after oxygen treatment tank 40 is anaerobic treated under natural flow through the flow buffer distribution tank 60. And a membrane separation process for solidifying the treated biomixture using a separation membrane and the biological treatment process including the step of internal transfer through the second transfer line 90 to the tank 20 to improve the water quality of the treated water. By introducing the MBR process, it is possible to secure safe and stable processing efficiency even under various load conditions. Introduction of the system and an additional carbon source is cheaper inputs and chemicals put into the process is not required to be maintained as well as easy operation management costs.

      Hereinafter, the present invention will be described in detail for each process with reference to FIGS. 1 and 2.

Phosphorus release process in anaerobic treatment tank

      Referring to FIG. 1, about 80% of influent water from which fine contaminants have been removed by a microscreen (not shown) flows into the anaerobic treatment tank 20 and emits phosphate (PO4-P) contained in the influent. The reaction takes place. At this time, the inside of the anaerobic treatment tank 20 is conveyed internally through the second conveying line 90 from the flow-rate distribution tank 60 at the inlet and the rear end, and the microbial mixture of the anaerobic treatment tank 20 does not sink. The stirrer 100 is installed to give a contact opportunity. The hydraulic retention time (HRT) in the anaerobic treatment tank 20 is about 1 hour.

Degradation and Nitrification Process of Organic Matter in Pre-treatment Tank

      Referring to FIG. 1, organic matter and nitrogen in the microbial mixed solution returned through the first conveying line 80 from the inflow water from the front anaerobic treatment tank 20 and the aerobic immersion membrane tank 50 at the rear stage are aerobic treatment tank. It is introduced into the preaerobic treatment tank 30 in which the acid generator 110 is installed, and organic matter decomposition and nitrification reaction are performed. HRT in this process is 2 hours to 3 hours.

      In order to optimize the nitrification of the influent and the internally transported microbial mixture, the tanks are divided into 3 to 4 tanks.These tanks are linked with dissolved oxygen (DO) or redox potential (ORP) concentrations to provide the appropriate amount of air to the tanks. Aeration blower 120 of the facility and the flow meter 170 to be provided.

Denitrification Process in Post Oxygen Treatment Tank

      Referring to FIG. 1, a denitrification reaction is performed in which a nitrogen oxide is reduced by using an internal transported nitrified microbial mixture introduced from the preaerobic treatment tank 30 and an organic material in a portion (about 20%) of the pretreated influent.

      At this time, in the after oxygen treatment tank 40, the stirrer 100 is installed to give a contact opportunity between the inflow water and the nitrified microbial mixture. The influent HRT (Hydraulic Retention Time, hydraulic retention time) in the post-oxygen treatment tank 40 is 2 hours to 3.5 hours.

       The microbial mixture is a microorganism for forcibly transferring the sum of the amount of each internal transfer to the anaerobic treatment tank 20 and the preaerobic treatment tank 30 and the amount of water treated by membrane separation filtration to the aerobic immersion membrane tank 50 at the rear stage. The mixed liquid transfer pump 200 is provided.

Organic Decomposition and Nitrification Process in Aerobic Submerged Membrane

       After passing through the anoxic treatment tank 40, the waste water is decomposed in the organic matter and nitrification of a predetermined portion as in the pre-treatment tank 30 described above by the separator blower 140 installed under the membrane unit 13. Happens. In addition, the flow buffer buffer tank 60 is installed at the front of the aerobic immersion membrane tank 50 to buffer the microbial mixture that has been conveyed from the post-oxygen treatment tank 40 and to return it internally to the anaerobic treatment tank 20 under natural flow. The second conveying line and a predetermined flow rate to be introduced into the natural flow into the aerobic immersion membrane tank 50.

       In addition, the microbial mixed solution nitrified in the aerobic immersion membrane tank 50 is composed of a first conveying line which naturally flows to the preaerobic treatment tank 30 at the front end at a predetermined flow rate fraction.

       At this time, the internal conveyance is controlled to interlock with the flow meter 170 and the flow control valve 180, respectively.

       At this time, the amount of the microbial mixed liquor conveyed to the pre-aerobic treatment tank 30 and the anaerobic treatment tank 920 via natural flow via the first conveying line 80 and the second conveying line 90 is about the amount Q of the influent. 2-4Q and 0.5-1Q are preferable, respectively. HRT in this process is about 1.5 to 2.5 hours.

      Phosphorus ingested in the microorganisms in the anaerobic treatment tank 20, the preaerobic treatment tank 30, the after anaerobic treatment tank 40, and the aerobic immersion membrane tank 50 at the front end is used to maintain the concentration of the microbial mixture in the entire treatment process. Sludge drawing pump 160 is provided to discharge excess sludge.

Membrane Filtration Process in Aerobic Submerged Membrane

       The anaerobic treatment tank 20 and the preaerobic treatment tank 30 by the first and second conveying lines 80 and 90 in the microbial mixed liquor forcedly transferred to the aerobic immersion membrane tank 50 by the microbial mixed liquor transfer pump 200. Except for the amount to be returned to the) is subjected to the solid-liquid separation process, such as the membrane filtration pump 150 and the membrane unit (130). The membrane device used in the solid-liquid separation process includes a membrane filtration pump 150 for producing treated water, a membrane unit 130 for performing solid-liquid separation, a washing tank for periodic chemical cleaning, and a periodic water backwash system if necessary. Consists of included equipment.

       Filtrate production through the membrane unit 130 allows the flow meter 17 and the membrane filtration pump 150 to monitor the amount of filtered water to interlock and produce a predetermined flow rate.

      Under the membrane unit 130, there is provided a separator blower 140 including an air diffuser associated with air cleaning to minimize clogging of the membrane.

      Membrane unit 130 is composed of a separate membrane module of the appropriate scale, in this case, the membrane used in the membrane separation process of the present invention, it is preferable to use an immersion flat membrane or immersion hollow fiber membrane, in addition to the pressurized tubular type by the properties of the influent Tubular membranes may also be used.

1 is a process diagram schematically showing a sewage, sewage and wastewater treatment process according to the present invention, a flow buffer distribution tank is introduced to reconfigure the reactor arrangement in order to secure the optimum efficiency of nitrification and to make the internal transfer non-powered. A diagram showing a state where two pump feeds are arranged.

     Figure 2 is a general anaerobic treatment tank + anaerobic tank + aerobic tank + aerobic immersion membrane configuration showing a process by a general two-stage power use internal transport.

     Figure 3 is a graph showing the BOD and its removal efficiency of the influent and treated water undergoing the process of the present invention.

     Figure 4 is a graph showing the T-N and its removal efficiency of the influent and treated water undergoing the process of the present invention.

     5 is a graph showing the T-P and its removal efficiency of the influent and treated water undergoing the process of the present invention.

     6 is a graph showing changes over time of the flux range and the intermembrane differential pressure in the membrane separation process of the present invention.

※ Explanation of symbols for main part of drawing.

10: raw water inlet 140: blower for membrane

20: anaerobic treatment tank 150: membrane filtration pump

30: pre-treatment tank 160: sludge drawing pump

40: back oxygen free treatment tank 170: flow meter

50: aerobic immersion membrane tank 180: flow control valve

60: flow buffer distribution tank 190: differential pressure gauge

70: treated water 200: microbial mixed solution transfer pump

80: first conveying line

90: second conveying line

100: Stirrer

110: aerobic treatment tank diffuser

120: aeration blower

130: membrane unit

Claims (7)

       In the method of treating wastewater,       (A) introducing a substantial portion (about 80%) of wastewater, pretreated by a microscreen, into an anaerobic treatment tank to maximize the release of phosphorus in the microbial mixture; (B) nitrifying the nitrogen component in the microbial mixture liquid introduced or internally transported in a natural flow in a subsequent aerobic immersion membrane tank under aerobic conditions and decomposing organic matters; (C) denitrifying the nitrified microbial mixture conveyed internally through a preliminary aerobic treatment tank and a preliminary aerobic treatment tank after introducing a portion (about 20%) of the wastewater into the post-oxygen treatment tank under pretreatment; (D) after the denitrification step, waste water is treated aerobicly in an aerobic immersion membrane tank to induce residual organic matter decomposition and nitrification, and then the nitrified microbial mixture at a predetermined ratio in the water level difference in the step (B). Internal conveyance by natural flow of water; And (E) solid-liquid separation of the microbial mixed solution passed through the step (D) by a membrane unit to produce treated water; (F) Phosphorus ingested in the microbial mixture in the anaerobic treatment tank, preaerobic treatment tank, after anaerobic treatment tank, and aerobic immersion membrane tank in the front end is included in the excess sludge discharged to maintain the concentration of the microbial mixture in the whole treatment process. Including the step of removing the phosphorus by discharging from the last tank, The microbial mixed solution passed through step (C) is transferred to a flow rate buffer distribution tank located at an upper portion of the aerobic immersion membrane tank at the rear end by using a transfer pump, and is distributed at a predetermined rate and returned to the anaerobic treatment tank as natural flow. And the flow rate of another predetermined ratio is distributed to the aerobic immersion membrane tank, In the step (D), the internal conveyance to the (A) and (B) step is made of natural flow and the internal conveying amount is 0.5 to 1.0Q in the (B) step, respectively, for the amount Q of the influent, (C Return to step) is 2.0Q to 4.0Q for the quantity Q of influent, In the step (B), in order to optimize nitrification, the preaerobic treatment tanks are divided into three to four, and the dissolved oxygen (DO) or redox potential (ORP) concentrations of these tanks are interlocked to supply an appropriate amount of air to each tank. Wastewater treatment method using biological treatment and immersion membrane filtration characterized by improving the nitrification efficiency under the conditions. delete delete delete         In the apparatus for treating wastewater, (A) anaerobic treatment tank equipped with a stirrer for maximizing the discharge of phosphorus in the waste water, pretreated by a fine screen; (B) a pre-treatment treatment tank equipped with an acid system to induce decomposition and nitrification of organic matter divided into three to four tanks to improve the nitrification efficiency and control the air volume; (C) a post-oxygen treatment tank equipped with a stirrer for denitrifying the waste water flowing down; (D) a transfer pump transfer facility to the aerobic immersion membrane tank in consideration of the internal transport amount and the treated water amount in the post-oxygen treatment tank described above; (E) a flow-buffering distribution tank for allowing a predetermined flow rate to be internally transferred to the anaerobic treatment tank through buffering and distributing the flow rate transferred from the post-oxygen treatment tank, and the predetermined flow rate to enter the aerobic immersion membrane tank; (F) an aerobic immersion membrane tank which induces organic decomposition and nitrification by aerobic treatment of wastewater introduced from the flow buffer distribution tank; (G) a membrane device including a membrane unit including a plurality of membrane modules for solid-liquid separation of the microbial mixture from the aerobic immersion membrane tank and a filtration pump; (H) the excess sludge drawing pump for maintaining the concentration of the microbial mixture in the treatment process and remove the absorbed phosphorus in the aerobic immersion membrane tank; (I) a part of the nitrified microbial mixture treated in the second conveying line and the aerobic immersion membrane tank for returning a part of the microbial mixture solution from the flow rate buffer tank to the anaerobic treatment tank to the natural oil tank. A first conveying line for conveying, The separator is a wastewater treatment apparatus using biological treatment and immersion membrane filtration characterized in that the immersion membrane. delete delete

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