WO2012036408A2 - Submerged-membrane bioreactor that easily responds to load regulation, and method of treating wastewater using the same - Google Patents

Abstract

The present invention relates to an advanced treatment process for sewage or wastewater using a membrane filter, and more particularly, to a submerged- membrane bioreactor that easily responds to load regulation, and to a method of treating wastewater using the same. An object of the present invention is to provide a submerged-membrane bioreactor that easily responds to load regulation, and specifically, to low loads. To achieve the above-described object, the present invention relates to a submerged-membrane bioreactor that easily responds to load regulation so that an advanced treatment of sewage and wastewater may be effectively realized using a submerged-membrane filter in which a portion of air (gas) used for cleaning a membrane is recirculated to easily adjust a dissolved oxygen concentration while maintaining a membrane-cleaning function, and a method of treating wastewater using the same. Since the submerged-membrane bioreactor may easily respond to load regulation, and specifically, to low loads, domestic sewage and wastewater treatment processes, which are frequently performed under low load in an initial test operation and operating processes, may be effectively and stably performed. Also, the quality of water may be improved, and the use of a treatment apparatus using the submerged membrane filter may be promoted.

Description

 [Specifications

 [Name of invention]

 Submerged membrane bioreactor and easy sewage treatment method

 Technical Field

 The present invention relates to a membrane bioreactor used for sewage or wastewater treatment, and more particularly, to a submerged membrane bioreactor and a sewage treatment method using the same. will be.

 Background Art

 <2> In sewage or wastewater treatment, the demand for cleaner discharged water quality continues to increase in order to strengthen the discharged water quality standards and protect the water quality environment.

In the past, it has been difficult to effectively remove SS (sustained substances), bacteria, viruses, and harmful protozoa from effluents in the sewage or wastewater treatment methods, mainly biological methods and gravity sedimentation.

 In particular, some harmful protozoa, such as giardia cysts or cyptosporidium, protozoa-induced lesions in the intestinal tract are not included in the water quality criteria, but are also removed by chlorine disinfection. The difficulty is increasing the need to remove these.

 <5> Membrane bioreactors replace the precipitation function with membranes in conventional bioreactors, and microfiltration membranes (MF) and ultrafiltration membranes are widely used in general applications. It is widely used because it is very effective for removing suspended solids, bacteria and protozoa.

 <6> Submerged membrane bioreactors in which membranes are immersed in submerged aerobic tanks (submerged in water) are widely used to save membrane installation area and improve membrane cleaning function.

 Submerged membrane bioreactors have the above advantages, while the membrane pores are so small that the membranes must be continuously cleaned to prevent the membranes from clogging and a large amount of air is required for cleaning. do.

<8> The amount of air required for membrane cleaning is 00 to 150 m ³ / itf.hr for the bottom area of the membrane, and the inflow load must be continuously supplied and cleaned at the time the membrane is operating regardless of the load of sewage. If less, the amount of air required for membrane cleaning may be much greater than the amount of air needed for biological treatment in the aerobic tank. Since the dissolved oxygen concentration of excessively increases, there is a big problem that the dissolved oxygen concentration in the aerobic tank cannot be adjusted to an appropriate value.

 As described above, the amount of cleaning air required for membrane cleaning is large and cannot be changed (reduced). Therefore, when the load of sewage flowing into the immersion membrane bioreactor is small, excess oxygen is supplied to the aerobic tank to increase the dissolved oxygen concentration. Total nitrogen and total nitrogen by increasing the dissolved oxygen concentrations in the anaerobic and anaerobic tanks, which are returned from the aerobic tank, and the anaerobic and anaerobic tanks to be aerobic, resulting in no phosphorus release or denitrification of microorganisms that occur only in anaerobic conditions. Phosphorus removal is extremely low or causes problems that cannot be removed.

 Since the amount of cleaning air of the filtration membrane described above corresponds to the amount of air required for the sewage treatment of the inflow sewage B0D concentration of 100 mg / L, the above problems occur in the advanced treatment of sewage having a lower B0D concentration.

 The above example illustrates the case of a microfiltration membrane (MF), but in the case of a high-treatment process in which an ultrafiltration (UF) membrane is applied to a bioreactor with a similar amount of membrane cleaning air but a much smaller membrane permeation rate than a microfiltration membrane. As described above, the amount of air required for cleaning becomes more excessive, and the influence on the advanced treatment process is absolute, and thus the application is further limited.

[Detailed Description of the Invention]

 [Technical problem]

 In sewage or wastewater treatment, even when the inflow load is low, the needle can maintain the membrane cleaning ability, and easily adjust the dissolved oxygen concentration in the aerobic tank to facilitate the change of load, and always maintain the normal treatment capacity. The present invention provides a membrane bioreactor and a sewage treatment method using the same.

Technical Solution

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

 Pretreatment to remove sand and contaminants in sewage;

 A flow rate adjusting step of storing the influent sewage for a predetermined time and transferring the sewage to the subsequent process evenly;

An anaerobic treatment step of mixing the inflow sewage and the return water returned from the degassing tank and releasing phosphorus absorbed by the microorganisms in the sludge while staying in the anaerobic tank for a predetermined time; An oxygen-free treatment step of removing nitrogen by denitrification by denitrifying bacteria by mixing the sewage passed through the anaerobic treatment step and the return water returned from the degassing tank for a predetermined time;

 An aerobic treatment step of supplying air to the sewage that has passed through the anoxic treatment step, staying in the aerobic tank for a predetermined time, and oxidizing the organic substance under aerobic conditions and causing nitrification;

 <21> Inject air from the membrane cleaner blower to the diffuser installed in the lower part of the immersion membrane filter in the membrane filtration tank, and wash the surface of the membrane of the immersion membrane filter by using the air cleaning function. After washing, some or all of the rising air (gas) is circulated to the inlet of the membrane cleaning blower to clean the membrane filter, and the dissolved oxygen concentration of the membrane filter tank is adjusted by adjusting the ratio of the circulating gas amount and the air amount. A membrane filtration treatment step of separating supernatant from sewage using a membrane filter;

 A degassing step of stopping air supply to the sewage passing through the membrane filtration step and holding it for a certain time to lower the dissolved oxygen concentration in the sewage; And

 Provided is a sewage treatment method using an immersion membrane bioreactor that can easily cope with load fluctuation, wherein the sewage from the degassing treatment step is returned to the anaerobic treatment step and the anaerobic treatment step.

 <24>

 Advantageous Effects

 The immersed membrane bioreactor of the present invention maintains the cleaning function by cleaning the air necessary for cleaning the membrane using a separate blower and recirculating some or all of the air rising above the water surface. The dissolved oxygen concentration in the membrane filtration tank can be maintained appropriately by adjusting the ratio of the gas volume and the air volume to be recycled, and the appropriate dissolved oxygen concentration can be maintained by controlling the air volume separately by installing an acid base and an aerobic blower in the aerobic tank. Even under heavy load fluctuations, it is easy to respond, so that the sewage can always be treated in the best condition.

<26>

 [Brief Description of Drawings]

<27> Figure 1 is an illustration of A _2/0 process using a membrane filtration tank according to the present invention.

<28> Figure 2 is an exemplary view of the _second A / 0 processes using a membrane filtration aerobic tank of the present invention.

3 is an exemplary diagram of an aerobic denitrification process using the membrane filtration tank of the present invention.

4 is a diagram illustrating the configuration of the anaerobic tank of the present invention. 5 is an exemplary view of the configuration of an aerobic denitrification tank of the present invention.

 6 is an exemplary view of the configuration of the membrane filtration tank of the present invention.

 7 is a diagram illustrating the configuration of an aerobic tank according to the present invention.

 8 is an exemplary view showing automatic control of an aerobic tank according to the present invention.

 9 is an embodiment of an aerobic tank used in the small sewage treatment facility of the present invention.

 <36>

 [Form for implementation of invention]

 Membrane filters form a unit by fixing a membrane to a frame and combining these units together to form a membrane filter.

 Membranes include microfiltration membranes (MF) and ultrafiltration membranes, depending on the eye size.

 (UF), nano membrane (NF), reverse osmosis membrane (R0), and microfiltration membrane and ultrafiltration membrane are mainly used for advanced treatment of sewage and wastewater.

 In addition, there are flat membranes, spiral membranes, cylindrical membranes, hollow fiber membranes, and the like, and hollow fiber membranes having a stable mechanical structure with a large volume of water can be secured in a small volume.

 As described above, the microfiltration membrane has a pore size in the range of 0.1 to 0.4, and can generally remove bacteria, Escherichia coli, protozoa, and fine suspended solids (SS).

 <4i> The ultrafiltration membrane has a pore size in the range of 0.001 to 0.05 mi, and can usually remove bacteria, E. coli, protozoa and viruses, and fine suspended solids (SS).

Due to the above characteristics, the water after membrane filtration is very clean, the use thereof is increasing.

 Membrane filters, however, have a very good performance in water treatment as described above, while the eye size is so small that they tend to be clogged.

 As a means to solve the above drawbacks, the membrane filter is immersed in the aerobic tank in which a large microbial floc is present, and the membrane filter is installed at the lower part of the membrane filter to prevent the membrane filter. Air is blown through the device to prevent clogging of the outer surface of the membrane filter using the cleaning power of air bubbles blown out from the diffuser.

 <45> The amount of air used to clean the membrane filter generally corresponds to the bottom area of the membrane filter.

150mVm ² .hr of air is required, and the greater the amount of air, the better the cleaning effect. In addition, the hypochlorite solution is periodically refluxed inside the hollow fiber membrane to clean the contaminants attached to the membrane.

 The amount of air cleaning the membrane filter, however, is a fixed value and must be kept constant at all times, regardless of the inflow load of sewage.

If the inflow load is small due to the low inflow of sewage or low pollution concentration, the air volume required in the aerobic tank decreases.In the case of a sewage treatment plant in Korea, the inflow load of sewage during the commissioning stage or the initial stage of operation is typically 30 ~ 50 ^< ¾ Since there are many places, the air volume required for the aerobic tank should also be supplied only 30-50% of the air volume calculated during design.

 However, the amount of air required for the membrane filter is usually 70 «¾ of the total required air volume, so that the aerobic tank becomes an excessively high dissolved oxygen concentration, and therefore, the anaerobic tank and the anoxic tank also become aerobic, which leads to extremely low nitrogen removal efficiency. And a treatment method using a membrane filter causes a problem in operation at the initial low load for the same reason.

 In the air, nitrogen is 78% and oxygen is 21%. The concentration of nitrogen and oxygen in water is determined by each Henry's constant.

Henry's constant E of nitrogen is 9.24 (EX10 ^-4 ) for water at 30 ^° C, Henry's constant of oxygen is 4/75 (EX10 一⁴ ), and the larger the Henry's constant, the less dissolved in water.

 Therefore, nitrogen is dissolved in water about 1/2 times less than oxygen, and in nitrogen at low pressure, inorganic nitrogen is dissolved at a low solubility that is equilibrium with the partial pressure of nitrogen gas in the air. Since it is not consumed by the air, nitrogen is not further dissolved even if it is continuously given up by supplying air or nitrogen gas into sewage.

 When air is supplied to the membrane filtration tank and the membrane filter is washed, oxygen in the supplied air is dissolved in sewage, but nitrogen is not dissolved.

In the air after being used to clean the membrane filter, the oxygen gas ratio decreases as much as dissolved, but the nitrogen gas remains as it was originally supplied, collects the air used for cleaning, and enters the membrane cleaning blower 620. In the circulating air (hereinafter referred to as the "circulating gas"), the oxygen gas rate is lowered and reduced to the partial pressure equilibrated with the dissolved oxygen concentration in the water. If no external air is supplied, all the oxygen in the circulating gas is consumed, and the oxygen partial pressure becomes zero, and the dissolved oxygen concentration in the membrane filtration tank becomes zero, resulting in anaerobic condition. will be.

 21% oxygen and 78% nitrogen are present in the air, so when the oxygen gas of the circulating gas recycled to the membrane cleaning blower is consumed, the volume of the circulating gas is reduced by the volume, but a small amount of air is continuously supplied from the outside. The volume of the circulating gas is then recovered as much as the initial volume of air, and nitrogen is the major part of the circulating gas and there is very little oxygen.

 Therefore, if the circulating gas is supplied to the inlet of the membrane cleaning blower, and only a part of the external air is supplied to adjust the ratio of the circulating gas amount and the external air amount, for example, when the inflow load of the sewage is small, the external air supply amount is reduced. When the inflow load of sewage increases, it increases the external air supply, circulates the circulating gas, maintains the amount of gas necessary for membrane cleaning, and effectively washes the membrane filter, while easily maintaining the dissolved oxygen concentration in the membrane filtration tank to the desired level. I can regulate it.

 In the present invention, the membrane filtration treatment step is configured using the same principle as above, and the configuration of the membrane filtration tank of the membrane filtration step is shown in FIG. 6.

The membrane filter 630 is installed in the water of the membrane filtration tank 610, and the membrane cleaning air diffuser 640 is installed below the membrane filter, and the membrane cleaning air diffuser is discharged from the outlet of the membrane cleaning blower 620. An air line was connected to the inlet of the device 640.

In addition, a blocking cover 650 was installed to seal the top of the membrane filtration tank 610 so that the air (= circulating gas) cleaned by the membrane filter could be collected at the top of the membrane filtration tank. A ventilation pipe 670 was provided in the shutoff cover to prevent negative pressure or static pressure from acting on the space sealed by the shutoff cover through the exhaust of remaining gas.

The circulating gas collected in the upper space of the membrane filtration tank is supplied to the membrane cleaning blower 620 through the gas circulation pipe 660 connected to the inlet pipe of the membrane cleaning blower 620 at the upper portion of the blocking cover 660. In order to circulate to the inlet of, and to control the amount of circulating gas circulating gas amount control valve 680 was installed.

An inlet pipe is installed at the inlet side of the membrane cleaning blower 620 to suck external air, and an air volume control valve 690 is installed at the inlet pipe to adjust the intake air amount.

According to the above-described configuration, the membrane filtration tank is maintained while controlling the ratio of supplying circulating gas and external air to the membrane cleaning blower according to the load amount of the inflow sewage, while maintaining the air amount (gas amount) required for membrane cleaning. The dissolved oxygen concentration in 610) can be easily adjusted to the desired concentration. Figure 1 is an exemplary view configure the membrane using a filtration tank, A _2/0 process described above.

A _2/0 process is one of the advanced treatment process of wastewater treatment, the method for removing the organic matter as well as nitrogen and phosphorus at the same time, how the biological process contained in the sewage, the most widely used worldwide, showing a good treatment outcome .

Figure 1 shows a modification of the example ₂ a standard A / 0 processes of the invention, numerous modifications, such as changing the process sequence or to a part omitted should be considered to be within the scope of the invention.

 Referring to the configuration of the process of Figure 1 as follows.

 Removes contaminants and sand contained in the sewage introduced in the pre-treatment step (100). Removed debris and sand are temporarily stored and released to the outside.

 The sewage from which the contaminants and sand are removed is introduced into the flow adjustment tank in the flow adjustment step and the flow rate is reduced while staying for a predetermined time, and the sewage is transferred to the anaerobic treatment step 300, which is the next process, by the inflow pump.

 In the anaerobic treatment step, the return water 1 (860) returned from the degassing treatment step (700) and the sewage are equally mixed in the anaerobic tank, and the microorganisms in the sewage discharge the phosphorus in the living body while remaining in the anaerobic state for a certain time. .

 4 illustrates the configuration of the anaerobic tank, and the sewage and the return water are introduced into the anaerobic tank 310, and the sewage and the return water are equally mixed by the action of the anaerobic agitator 320. In order to promote phosphorus release, the 0RP (redox potential) value should be maintained at -300 ~ 400mV and the dissolved oxygen concentration should be kept below O.lmg / L.

 The sewage that has passed through the anaerobic stage is sent to an anaerobic treatment stage 400.

* In the anaerobic treatment step, the sewage and return water 2 (850) flows into the anaerobic tank 410 and is mixed evenly by the action of the anaerobic tank stirrer 320.

 In the anaerobic treatment step, the nitrate nitrogen is converted to inorganic nitrogen by the denitrification of the denitrifying bacteria in the anaerobic state, and released into the atmosphere, thereby removing nitrogen from the sewage.

 The anaerobic and anaerobic tanks need to be sealed or covered with a top to prevent contact with oxygen or air.

The sewage that has passed the anaerobic treatment step is sent to the aerobic treatment step 500. In the aerobic treatment step, the organic matter in the sewage is decomposed, nitrification is carried out to convert ammonia nitrogen to nitrate nitrogen, and the phosphorus-treated microorganism that has released phosphorus in the anaerobic treatment step 300 is about 2 to 6 times more than the normal phosphorus absorption amount. Phosphorus over-absorption acts to absorb a larger amount of phosphorus in the vessel, and the phosphorus in the sewage is removed by releasing the excess phosphorus microorganisms into the excess sludge in the subsequent degassing step.

 The aerobic treatment step maintains the dissolved oxygen concentration at 2.0 to 4.0 mg / L in the advanced treatment process for nitrogen and phosphorus removal. However, the aerobic treatment step should be kept low unless the concentration of organic matter in the sewage is low, as long as it does not interfere with nitrification. It is desirable to maintain 1.5 ~ 2.0mg / L.

 In the aerobic treatment stage, especially when the sludge is charged or not completely mixed when supplying air to maintain the dissolved oxygen concentration in the diffuser due to the small load of inflow sewage, the air diffuser for supplying air as shown in FIG. In addition to the apparatus 530, an aeration tank stirrer 520 for agitation may be optionally installed.

 The sewage passing through the aerobic treatment step is transferred to the membrane filtration treatment step 600, as shown in FIG. 6, the supernatant is separated from the membrane filter 630, and the remaining sewage is transferred to the degassing treatment step 700.

 In the membrane filtration step, the washing of the membrane filter is important in relation to the separation of the supernatant water, so that the dissolved oxygen concentration in the membrane filtration tank 610 is not higher than the optimum value (1.5 to 2.0 mg / L) due to the washing air. shall.

 As described above, the present invention can effectively clean the membrane filter by adjusting the ratio of supplying circulating gas and external air to the membrane cleaning blower 620, and also maintain the dissolved oxygen concentration in the membrane filter tank 610 in an appropriate range. It was. (See Figure 6)

 The sewage remaining after separating the supernatant from the membrane filtration treatment step (600), is maintained in the degassing step (700) with the air supply interrupted for a certain time, so that the dissolved oxygen concentration in the sewage to less than 0.5mg / L Lowering, a part is returned to the anaerobic treatment step 300 (860), and a part is returned to the anaerobic treatment step 400 (850). (Returning refers to the transfer of a mixture containing sewage and activated sludge to an anaerobic or anaerobic treatment step, and the returned sewage is called "return water")

In the degassing step, the remaining sludge is more than the amount of sludge needed in the treatment process, and the excess sludge is disposed of by discharging it out of the process to remove phosphorus in the sewage due to the disposal of the excess sludge. Although not shown, it is preferable to install a stirrer to prevent sludge settling in the degassing step.

 The sewage is treated while repeating the above process.

2 is by way of illustration of A _2/0 process using a membrane filtration aerobic tank of the present invention, wherein Fig.

In the process exemplified in step 1, the aerobic treatment step and the membrane filtration treatment step are combined into one step to form a membrane filtration aerobic treatment step.

 The contaminant treatment step 100 and the flow rate adjustment step 200 of the present process are the same as those already described above, and thus description thereof is omitted.

 In the anaerobic treatment step 300, while the return water 2 860 and the sewage returned from the degassing treatment step 700 are equally mixed in the anaerobic tank by the action of the stirrer, the phosphorus-removing microorganism is living in the anaerobic state for a certain time. The phosphorus accumulated in the body is released.

 The sewage that has passed through the anaerobic treatment stage is an anaerobic treatment stage in the anaerobic treatment stage 400 and the sewage and return water 1 (850) evenly mixed in the anaerobic tank, the action of the stirrer, while staying in an anaerobic state for a certain time With the action of denitrifying bacteria, nitric acid nitrogen in sewage is converted to inorganic nitrogen gas and released into the atmosphere to remove nitrogen. The sewage that has passed through the anaerobic treatment step is sent to the membrane filtration aerobic treatment step 500B.

 7 is an example attempt for the construction of an aerobic tank of the membrane filtration aerobic treatment step 500B of the present invention.

 A membrane filter 630 is installed in the internal water of the aerobic tank 510, and a membrane cleaning diffuser 640 is installed at the lower portion of the membrane filter to remove the membrane cleaner. The outlets were connected by air piping.

 In addition, near the bottom of the bottom of the exhalation tank 510, an air diffuser 530 for supplying air to the exhalation tank was installed, and also connected to the discharge port of the membrane filtration exhalation tank blower 550 by an air pipe.

 The upper portion of the exhalation tank 510 was installed by blocking the cover 650, the upper space of the exhalation tank was sealed by air, and the ventilation cover 670 was installed in the blocking cover to communicate with the atmosphere.

 The aeration pipe is to prevent the occurrence of negative pressure (-pressure) or positive pressure (+ pressure) in the space above the aeration tank and to exhaust the air (circulating gas) remaining after the aeration.

A gas circulating pipe 660 was connected from the upper portion of the blocking cover 650 to the inlet of the membrane filtration aeration tank blower 550, and a circulating gas flow control valve 560 was installed in the gas circulation pipe. It was done.

 <ιοο> When the membrane filtration exhalation tank blower 550 is operated to supply air to the exhalation tank, the air is supplied to the air purifier 530 and the membrane cleaning air purifier 640, and the air is supplied to the sewage inside the exhalation tank to be dissolved. The oxygen concentration is maintained, and the membrane of the membrane filter is cleaned by using the cleaning action generated when air is floating.

 <ιοι> After the air is supplied to the sewage and the membrane is cleaned, the air collects in the upper space of the aerobic tank, and this air is a gas with relatively high nitrogen and relatively low oxygen. 660 is circulated through the membrane filtration aeration tank blower 550.

 At the inlet side of the membrane filtration exhalation tank blower, an air inlet pipe for inhaling air in the atmosphere is installed, and an air volume control valve for adjusting the intake air amount is installed.

 In order to maintain the dissolved oxygen concentration in the aerobic tank at a desired value, the opening degree of the air flow control valve 570 and the circulating gas flow control valve 560 provided at the inlet of the membrane filtration aerobic blower 550 is controlled. Adjust the ratio between the amount of intake air and the amount of circulating gas to achieve the desired dissolved oxygen concentration.

Although the amount of air sucked in and the amount of circulating gas change depending on the opening degree of the valve, the amount of air discharged from the membrane filtration aeration tank blower ₅₅₀ (combined air of the air and the circulating gas) is constant. Due to the low load, the amount of air required to maintain the dissolved oxygen concentration appropriately decreases, so that even if the amount of air supplied from the outside is reduced, the cleaning action for cleaning the membrane filter is kept constant.

 8 shows the oxygen concentration meter 10, the automatic controller 30, the circulating gas volume automatic control valve 560a and the air volume automatically in the water of the aerobic tank 510 in the membrane filtration aerobic treatment step of the present invention. The example which installed the valve 570a and controls it automatically so that the dissolved oxygen concentration in an aerobic tank may be kept at the set value is shown.

 If the dissolved oxygen concentration in the aerobic tank measured by the dissolved oxygen concentration meter 10 is smaller than the set value, the automatic controller 30 increases the opening degree of the air volume control valve 570a and increases the amount of air sucked from the outside. If the dissolved oxygen concentration in the exhalation tank is larger than the set value, the automatic controller sets the dissolved oxygen concentration in the exhalation tank by increasing the opening degree of the circulating gas amount automatic control valve 560a and decreasing the opening degree of the air volume automatic control valve 570a. Keep it constant at one value.

9 shows an embodiment of an aerobic tank in which the present invention is applied to a small sewage treatment facility. All.

 If the number of membrane filters 630 is small, such as a small sewage treatment plant or village sewage system, between one and two or three, the upper portion of the aerobic tank may be closed with a shield cover, and the upper portion of each membrane filter 630 may be closed. It is often more economical to install the blocking covers 650 individually.

 In the case described above, the membrane filter 630 is installed in the water of the aerobic tank 510, the membrane cleaning diffuser 640 is installed below the membrane filter, and the membrane cleaning diffuser and the membrane cleaning blower 620 are provided. ) Between the discharge port is connected to the air piping.

 From the upper part of the blocking cover 650 installed separately for each membrane filter, the inlet side of the membrane cleaning blower 620 was connected to the gas circulation pipe 660, and the gas circulation pipe was provided with a circulating gas flow control valve 680. On the inlet side of the membrane cleaning blower 620, a suction pipe for inhaling air in the atmosphere was installed, and an air volume control valve 690 for adjusting the intake air amount was installed.

 In addition, an air diffuser 530 for abandoning the aerobic tank was installed near the inner bottom of the aerobic tank 510, and the air outlet was connected between the air diffuser and the discharge port of the membrane filtration aerobic blower 550.

 In order to control the dissolved oxygen concentration, the amount of air supplied to the air diffuser is controlled by releasing some discharged air into the atmosphere from the noise blower 590 and controlling the number of revolutions of the blower. Can be.

 In order to clean the membrane filter 630 and to adjust the dissolved oxygen concentration, the method of adjusting the ratio of the amount of circulating gas and the amount of hop-in air is the same as described above.

 3 is an exemplary view of a sewage treatment process using the membrane filtration tank of the present invention.

 A pretreatment step (100) for removing contaminants and sand in the introduced sewage;

 Flow rate adjustment step 200 to maintain the sewage for a certain time;

 An anaerobic treatment step 300 of mixing sewage and return water to release phosphorus in the microorganism in the anaerobic state;

 An aerobic denitrification treatment step 500A that maintains a low dissolved oxygen concentration and a specific redox potential value, decomposes organic matter in the sewage, denitrates nitrogen, and allows the microorganism to absorb excessively phosphorus;

Membrane that keeps dissolved oxygen concentration of sewage at l ~ 2.0mg / L, activates microorganism, converts some untreated ammonia nitrogen to nitrate nitrogen, and separates supernatant Filtration treatment step 600;

 Degassing treatment step 700 to lower the dissolved oxygen concentration in the sewage;

 Provided is a sewage treatment method using a submerged membrane bioreaction device that is easy to vary in load, characterized by consisting of a conveying pump 800 and a conveying water 900.

 The pretreatment step 100 and the flow rate adjusting step 200 are as described above, and in the anaerobic treatment step 300, the return water 900 and the sewage are mixed in the anaerobic tank 310 as shown in FIG. During a certain period of time, the phosphorus contained in the microorganisms is released, and the nitric acid nitrogen contained in traces in the return water is converted to nitrogen gas by the action of denitrifying bacteria.

In the aerobic denitrification step 500A, an air diffuser 530 is installed near the inner bottom of the aerobic denitrification tank 510a, and an aerobic denitrification stirrer 520a is installed. The discharge port of the air diffuser and the blower blower ₅₄₀ was connected by air piping.

 The dissolved oxygen concentration of the aerobic denitrification tank (510a) is kept relatively low at 0.3 ~ 0.5mg / L by controlling the air supply of the aerobic blower, and the redox potential (0RP) is maintained at + 330mV based on the hydrogen electrode. In this case, ammonia nitrogen in sewage is oxidized to nitrate nitrogen by the action of aerobic denitrification bacteria, and at the same time, denitrification occurs by conversion to nitrogen gas.

 In addition, the microorganisms that released phosphorus in the anaerobic treatment step absorb excess phosphorus in aerobic state, and organic matter is decomposed and treated in aerobic state.

 The membrane filtration tank of the membrane filtration treatment step 600 was configured as shown in FIG. 6, and the configuration and operation were as described above, but the dissolved oxygen concentration in the membrane filtration tank 610 was maintained at 1.0 to 2.0 mg / L for a predetermined time. By treatment, the activity of the microorganism is increased, and ammonia nitrogen, which may not be partially nitrified in the aerobic denitrification tank 510a due to the action of nitrifying bacteria, is oxidized to nitrate nitrogen.

 Also in the membrane filtration treatment step, sewage and supernatant are separated in membrane filter 630.

 The advantage of aerobic denitrification is that the amount of air required is low, and in theory, 100% of denitrification is possible if the operating conditions such as pH, ORP and HRT are ideally maintained.

 In the degassing treatment step 700, the supply of air to the sewage is stopped for a certain time, and the dissolved oxygen concentration of the sewage is kept lower than 0.5 mg / L to increase the treatment effect of the anaerobic treatment step, which is a connecting process.

 By removing excess sludge in the degassing step, phosphorus in the sewage is removed.

Claims

 [Range of request]  [Claim 11  A membrane filter 630 installed in an aerobic tank 510 or a membrane filtration tank 610 in a sewage treatment process to separate supernatant water; Membrane dispersing device (640) for cleaning the membrane of the membrane filter by installing in the lower part of the membrane filter and blocking cover (650) installed on the upper part of each membrane filter (630) to collect the air (gas) after washing. )Wow; Air piping, a circulating gas flow control valve 680, and an air flow control valve connecting a gas circulation pipe 660 connecting the cutoff cover to the inlet of the membrane cleaning blower 620, an outlet of the membrane cleaning air blower, and an outlet of the membrane cleaning blower. An immersion membrane bioreactor easy to respond to load variations, characterized in that it comprises a (690). [Claim 2]  Pretreatment step 100 to remove sand and contaminants in sewage;  A flow rate adjusting step 200 for storing the inflow sewage for a predetermined time and transferring the sewage to a subsequent process evenly;  An anaerobic treatment step 300 of mixing the inflow sewage and the return water returned from the degassing tank and releasing the phosphorus absorbed by the microorganisms in the sludge while staying in the anaerobic tank for a predetermined time;  An oxygen-free treatment step 400 for mixing nitrogen from the sewage passing through the anaerobic treatment step and return water returned from the degassing tank to remove nitrogen by denitrification by denitrifying bacteria while staying in the oxygen-free tank for a predetermined time;  An aerobic treatment step (500) of supplying air to the sewage that has passed through the anoxic treatment step, and staying in the aerobic tank for a predetermined time, oxidizing organic matter and nitrifying under aerobic conditions; Injects the air transferred from the membrane cleaning blower 620 to the membrane cleaning air disperser 640 installed in the lower part of the immersion membrane filter 630 located in the membrane filtration tank 610, and utilizes the cleaning action of the floating air. To clean the membrane surface of the submerged membrane filter, and to collect the air (gas) which rises after washing in the blocking cover 650 provided at the upper part of the membrane filtration tank 610 to block some or all of the gas. The membrane filter is cleaned while circulating to the inlet of the cleaning blower, the ratio of the amount of circulating gas to the amount of air is adjusted, the dissolved oxygen concentration in the membrane filtration tank is also controlled, and the immersion membrane filter is used in the sewage through the aerobic treatment stage. Membrane filtration treatment step 600 of separating the supernatant; Degassing step to stop air supply to the sewage through membrane filtration step and stay for a certain time to lower dissolved oxygen concentration in the sewage and discharge excess sludge (700); and  A sewage treatment method using an immersion membrane bioreactor, which is easy to change in load, characterized in that the sewage from the degassing step is returned to the anaerobic step and the anaerobic step. [Claim 3]  Pretreatment step 100 to remove sand and contaminants in sewage;  A flow rate adjusting step 200 for storing the inflow sewage for a predetermined time and transferring the sewage to a subsequent process evenly;  An anaerobic treatment step 300 of mixing the inflow sewage and the return water returned from the degassing tank and releasing the phosphorus absorbed by the microorganisms in the sludge while staying in the anaerobic tank for a predetermined time;  An oxygen-free treatment step 400 for mixing nitrogen from the sewage passing through the anaerobic treatment step and return water returned from the degassing tank to remove nitrogen by denitrification by denitrifying bacteria while staying in the oxygen-free tank for a predetermined time;  An immersion type membrane filter 630 is installed inside the aerobic tank 510 having a blocking cover 650 on the upper side, and a membrane filtration aeration tank blower 550 in the membrane cleaning air disperser 640 installed at the lower part of the membrane filter. Spray the air transported from the air) and clean the membrane surface of the submerged membrane filter using the cleaning action of the rising air, and then remove some or all of the rising air (gas) to the inlet of the membrane filtration tank blower. The membrane filter is washed while circulating, the air purifier 530 installed near the bottom bottom of the aerobic tank is sprayed with air from the membrane filtration aeration tank blower, and the ratio of the amount of circulating gas flowing into the membrane filtration aeration tank blower and the amount of air flows. Adjusting the dissolved oxygen concentration in the membrane filtration tank, and using a submerged membrane filter, a membrane filtration aerobic treatment step of separating supernatant from the aerobic sewage treatment step (500B);  A degassing treatment step 700 of stopping the air supply to the sewage passing through the membrane filtration aerobic treatment step and dwelling for a predetermined time to lower the dissolved oxygen concentration in the sewage and discharging excess sludge; And The submerged membrane bioreactor device, which is configured to return the sewage from the degassing step to the anaerobic step and the anaerobic step, is easy to change the load. Sewage Treatment Method [Claim 4]  A pretreatment step (100) for removing contaminants and sand in the introduced sewage;  A flow rate adjusting step of maintaining the sewage for a predetermined time (200);  An anaerobic treatment step 300 of mixing sewage and return water to release phosphorus in the microorganism in the anaerobic state;  An aerobic denitrification treatment step 500A that maintains a low dissolved oxygen concentration and a specific redox potential value to decompose organic matter in the sewage, denitrify nitrogen, and allow the microorganism to absorb excess phosphorus;  Injects the air transferred from the membrane cleaning blower 620 to the membrane cleaning air disperser 640 installed in the lower part of the immersion membrane filter 630 located in the membrane filtration tank 610, and utilizes the cleaning action of the floating air. To clean the membrane surface of the submerged membrane filter, and to collect the air (gas) which rises after washing in the blocking cover 650 installed on the upper part of the membrane filtration tank 610, to block some or all of the gas. The membrane filter is washed while circulating through the inlet of the cleaning blower, and the ratio of the amount of circulating gas and the amount of air is controlled to adjust the dissolved oxygen concentration in the membrane filter tank, while maintaining the dissolved oxygen concentration in the sewage at 1 ᅳ 2.0mg / L. A membrane filtration treatment step 600 of increasing the activity of microorganisms and converting some untreated ammonia nitrogen to nitrate nitrogen, and separating the supernatant from sewage using an immersion membrane filter; A degassing treatment step 700 for lowering dissolved oxygen concentration in the sewage and discharging excess sludge;  A sewage treatment method using an immersion membrane bioreactor that is easy to cope with load fluctuation, characterized in that it comprises a conveying pump 800 for conveying the return water 900 in the anaerobic treatment step. [Claim 5] The method according to claim 3, wherein the dissolved oxygen concentration meter 10 is installed in the aerobic tank, the dissolved oxygen concentration is received, and the circulating gas volume automatic control valve and the air volume automatic control valve are adjusted so that the dissolved oxygen concentration matches the set dissolved concentration value. A sewage treatment method using an immersion type membrane bioreactor that is easy to cope with load fluctuation, characterized by including an automatic controller (30) for controlling. [Claim 6]  The submerged membrane bioreactor according to any one of claims 2 to 4, wherein the blocking cover 650 is provided on an upper portion of each membrane filter 630. Sewage treatment method using.