KR101085872B1 - Wastewater treatment system using a membrane - Google Patents

Abstract

PURPOSE: A system for treating waste water using a membrane is provided to prevent the damage of the membrane by diluting chlorine dioxide at a pre-set concentration before the chlorine dioxide is used. CONSTITUTION: A system for treating waste water using a membrane includes a bioreactor. The bioreactor includes an anaerobic bath, an anoxic bath, and an aerating bath. The bioreactor further includes an immersing membrane(110), a treating water circulating pipe(261), and a chlorine dioxide supplying pipe(221). A sodium hydroxide supplying pipe(231), an organic acid supplying pipe(241), and a washing water supplying pipe(251) are further included in the bioreactor. A controlling valve(300) is installed at the chlorine dioxide supplying pipe, the sodium hydroxide supplying pipe, the organic acid supplying pipe, and the washing water supplying pipe.

Description

Wastewater treatment system using a membrane

The present invention relates to a wastewater treatment system using a separator, and more particularly, to immerse an immersion type membrane in an aerobic tank of a bioreactor in a wastewater treatment system using a MBR (Membrane Bio-Reactor) process, and dilute the membrane to a predetermined concentration. By supplying chlorine dioxide, citric acid, sodium hydroxide and washing water at regular intervals for a certain time, to improve the cleaning efficiency of the membrane, and to a wastewater treatment system using a separator that can be continuously operated without downtime.

The general sewage treatment and wastewater treatment process is a biological process using activated sludge and adopts a method of reducing the concentration of organic substances in sewage and wastewater by allowing aerobic microorganisms to oxidize and acquire organic matters under aerobic conditions. In addition, to maintain the concentration of microorganisms in the reaction tank, to operate the precipitation tank to prevent the outflow of particulate matter and activated sludge in the treated water. However, these standard activated sludge processes settle due to changes in ambient conditions such as temperature, pH, and concentration of contaminants in influent, resulting in severe fluctuations in the water quality of the final treated water. When activated sludge is included in the final treated water due to deterioration of sedimentation property, the sludge has a high organic matter concentration by the activated sludge.

In addition, the general standard activated sludge process can only process organic matter based on carbon, but cannot process nitrogen and phosphorus which cause eutrophication in rivers and lakes. Various processes have been proposed to satisfy the discharged water quality standards of sewage treatment facilities. The most common and common method for the treatment of nitrogen and phosphorus is the A2O (Anaerobic + Anoxic + Oxic) process, which is an organic material of sewage and wastewater introduced through a multi-step process in which microorganisms are varied to anaerobic, anaerobic and aerobic conditions. And nutrients. Phosphorus is released in the anaerobic state, and the released phosphorus is removed by luxury uptake as the microorganism grows in aerobic conditions and the excess sludge is removed from the process. In the aerobic state, as described above, microorganisms grow, phosphorus is excessively ingested, organic matter is oxidized, and ammonia nitrogen is converted into nitrite nitrogen (NO3-Nitrate) via nitrite nitrogen (NO2-, Nitrite). do. The nitrogen component thus converted is introduced into the anoxic tank through the internal transport, is reduced to nitrogen gas (N2) in the anoxic state and disappeared into the atmosphere.

Most biological nitrogen and phosphorus removal processes are based on A2O processes. However, in the case of the A2O process, the final step for producing the final treated water is passed through the settling tank, as in the standard activated sludge method described above, there is a problem of deterioration of the treated water due to sedimentation of the activated sludge.

In order to prevent the deterioration of treated water quality due to the sedimentation of activated sludge, a membrane filtration process for separating microorganisms and treated water has been introduced since the 1980s. Membrane filtration process is made of polyethylene (PE), polypropylene (PP), polysulfone (PSf), polyisulfone (PES), PVDF, etc., and the surface diameter of Da (Dalton) to several hundred thousand Da (Dalton) on the surface It is a process using a separator produced in the form of a flat plate or hollow fiber having a. Separation membranes commonly used in sewage or water treatment processes are microfiltration membranes (MF) or ultrafiltration membranes (UF, Ultra-Filtration) and have pore diameters ranging from 0.001 μm to 1.0 μm.

The separator can completely exclude the passage of particulate matter larger than the pore size. Due to this characteristic, when the membrane filtration process is introduced into the sewage and wastewater treatment process, it is possible to completely remove the particulate matter regardless of the sedimentation of activated sludge, thereby ensuring a stable treatment water at all times. In addition, the outflow of activated sludge from the microbial reactor can be completely excluded, and it is possible to maintain the high microbial concentration in the reactor because it is easy to control the activated sludge concentration. Maintaining a high microbial concentration in a biological treatment process means maintaining a concentration of a large number of active microorganisms per unit volume, which allows for the treatment of larger amounts of sewage and wastewater through smaller sites. It also enables stable processing for high organic loads. This is commonly referred to as MBR (Membrane Bio-Reactor) process.

However, the MBR process has limitations due to the advantage of maintaining high microbial concentration in the reactor. The high concentration of activated sludge flowing into the membrane filtration tank accumulates on the membrane surface, causing a problem of membrane fouling.

Membrane contamination serves to raise the filtration pressure by the accumulation of contaminants (or activated sludge) in the membrane surface or membrane pores. Increasing the filtration pressure reduces the efficiency of treated water production and requires physical and chemical cleaning to remove it.

The most common method for controlling membrane fouling is to provide air to the membrane surface at the same time the membrane performs membrane filtration so that the direction of the fluid to form a cross-flow direction with the filtration direction. Typically, when the activated sludge concentration is high or a high flux is required, the amount of air supplied increases rapidly. Since a blower or compressed air is required for the air supply, a higher air supply requires more energy use.

In addition, in order to restore the filtration capacity of the contaminated membrane, a high concentration of acid or base wash is performed. However, the high concentration of acid and base used at this time may affect the membrane material, resulting in shortening the life span of the membrane, and affecting microorganisms.

In addition, the MBR process is generally operated for 7 minutes and interrupted operation for 3 minutes to prevent the blockage of the separator. In this case, since the actual membrane operating time is about 17 hours in 24 hours, the treatment efficiency is lowered.

Accordingly, there is a need for the development of an MBR process that can solve the membrane contamination problem as described above and at the same time improve the processing efficiency by extending the operation time.

The present invention has been made to solve the problems described above, an object of the present invention is to immerse the immersion membrane in the aerobic tank of the bioreactor in the wastewater treatment system using the MBR (Membrane Bio-Reactor) process, By supplying chlorine dioxide, citric acid, sodium hydroxide, and washing water diluted to a certain concentration at regular intervals for a predetermined time, to improve the cleaning efficiency of the membrane to provide a wastewater treatment system using a separator that can be continuously operated without downtime.

In addition, it is an object of the present invention by diluting chlorine dioxide to a certain concentration, the wastewater treatment system using a separation membrane that can effectively clean the membrane contaminants without damaging the material of the membrane, without affecting the microorganisms To provide.

In addition, the object of the present invention is to clean the separation membrane with citric acid and sodium hydroxide as well as chlorine dioxide, it is possible to improve the cleaning efficiency by acid and base washing, and wastewater treatment system using a separation membrane that can simultaneously suppress inorganic occlusion and organic occlusion To provide.

The wastewater treatment system using the separation membrane of the present invention is a wastewater treatment system (1) using a separation membrane having a bioreactor (100) including an anaerobic tank (40), an anaerobic tank (50) and an aerobic tank (60), wherein the bioreactor 100 is an immersion type membrane 110 immersed in the aerobic tank 60 so that the mixture outside the separator is introduced into the separator through the separator pore and separated into a solid solution; And a chlorine dioxide generator 210 for electrolytically dissolving sodium chlorite such that chlorine dioxide and sodium hydroxide diluted to a certain concentration are produced, a chlorine dioxide tank 220 in which the chlorine dioxide generated by electrolysis is stored, and sodium hydroxide. A membrane cleaning device 200 including the sodium hydroxide tank 230 to be stored, the organic acid tank 240 to store the organic acid, and the washing water tank 250 to store the washing water; Is further provided, the chlorine dioxide, sodium hydroxide, organic acid and the washing water through the membrane cleaning device 200 is injected into the aerobic tank 60 at regular intervals for a predetermined time to clean the immersion membrane 110 It features.

In addition, the wastewater treatment system 1 using the separator is a treated water circulation pipe 261 for circulating the treated water to the immersion type membrane 110, the chlorine dioxide tank 220, sodium hydroxide tank 230, organic acid A chlorine dioxide supply pipe 221, a sodium hydroxide supply pipe 231, an organic acid supply pipe 241, and a wash water supply pipe 251 to which the tank 240 and the washing water tank 250 are connected, respectively; And a control valve 300 installed in the chlorine dioxide supply pipe 221, the sodium hydroxide supply pipe 231, the organic acid supply pipe 241, and the washing water supply pipe 251 to control the supply of chlorine dioxide, sodium hydroxide, organic acid, and washing water; And is formed to include a plurality of protrusions.

In addition, the wastewater treatment system 1 using the separator is installed in connection with the control valve 300, the control unit 400 to adjust the chlorine dioxide, sodium hydroxide, organic acid and washing water to be sequentially supplied at a predetermined interval for a predetermined time It is characterized in that it further comprises a).

In addition, the wastewater treatment system 1 using the separation membrane is further provided with a differential pressure gauge for measuring the filtration pressure in the surface of the immersion separation membrane 110 or the membrane supply, the control unit 400 is connected to the differential pressure gauge of the differential pressure gauge When the pressure reaches a predetermined pressure, the control valve 300 is opened to supply chlorine dioxide, sodium hydroxide, organic acid and washing water.

In addition, the wastewater treatment system 1 using the separator is characterized in that chlorine dioxide, sodium hydroxide, organic acid is sequentially supplied, washing water is supplied between the chlorine dioxide, sodium hydroxide, organic acid is supplied.

In addition, the organic acid tank 240 is characterized in that citric acid or oxalic acid is stored.

In addition, the wastewater treatment system 1 using the separator is characterized in that chlorine dioxide is diluted to a concentration of about 450 ~ 550mg / L is stored in the chlorine dioxide tank 220.

The wastewater treatment system using the membrane of the present invention is immersed in the aerobic tank of the bioreactor in the wastewater treatment system using the MBR (Membrane Bio-Reactor) process, chlorine dioxide, citric acid, hydroxide diluted to a certain concentration in the membrane By supplying sodium and washing water at regular intervals for a certain time, it improves the cleaning efficiency of the membrane and has the advantage of being able to operate continuously without downtime.

In addition, the wastewater treatment system using the separation membrane of the present invention by diluting the chlorine dioxide to a certain concentration, without damaging the material of the membrane, and does not affect the microorganisms and at the same time can effectively perform the cleaning of the membrane contaminants There is this.

In addition, the wastewater treatment system using the separation membrane of the present invention can improve the cleaning efficiency by acid and base cleaning, by cleaning the separation membrane with citric acid and sodium hydroxide as well as chlorine dioxide, and can simultaneously suppress inorganic and organic blockage. There is this.

In addition, the wastewater treatment system using the separator of the present invention has the advantage that it does not need to add a basic cleaning material by using sodium hydroxide which is naturally produced by the electrolysis of sodium chlorite as the membrane cleaning material.

In addition, the wastewater treatment system using the separation membrane of the present invention has the advantage that by improving the separation membrane cleaning effect to enable the continuous operation of the separation membrane, it is possible to increase the wastewater treatment capacity and greatly improve the treatment efficiency.

1 is a block diagram of a wastewater treatment system using a conventional membrane.
2 is a block diagram of a wastewater treatment system using a separator according to the present invention.
Figure 3 is a schematic diagram showing the immersion separator and the membrane cleaning device provided in the wastewater treatment system using a separator according to the present invention.

Hereinafter, the wastewater treatment system using the separator of the present invention as described above will be described in detail with reference to the accompanying drawings.

1 is a block diagram of a wastewater treatment system using a conventional membrane, Figure 2 is a block diagram of a wastewater treatment system using a separator according to the present invention, Figure 3 is provided in a wastewater treatment system using a separator according to the present invention It is a schematic diagram showing the immersion membrane and the membrane cleaning device.

Wastewater treatment system 1 using the separation membrane of the present invention is a wastewater treatment system 1 using a separation membrane provided with a bioreactor 100 including an anaerobic tank 40, an anaerobic tank 50 and an aerobic tank 60, The bioreactor 100 is provided with an immersion type membrane 110 and a membrane cleaning device 200.

The immersion separator 110 is immersed in the aerobic tank 60 so that the mixture outside the separator flows into the separator through the separator pore and is separated into a solid solution.

The separator cleaning device 200 is a chlorine dioxide generator 210 for electrolyzing sodium chlorite so that chlorine dioxide and sodium hydroxide diluted to a certain concentration, chlorine dioxide stored in the chlorine dioxide generated by electrolysis A tank 220, a sodium hydroxide tank 230 in which the sodium hydroxide is stored, an organic acid tank 240 in which the organic acid is stored, and a washing water tank 250 in which the washing water is stored are formed.

At this time, the wastewater treatment system 1 using the separator is injected into the aerobic tank 60 at regular intervals for a predetermined time period through the separator cleaning device 200 and chlorine dioxide, sodium hydroxide, organic acid and washing water. By cleaning the knowledge separation membrane 110, it is possible to prevent the separation membrane from being blocked.

As shown in FIG. 2, the wastewater treatment system 1 using the separator is compared with the wastewater treatment system 1 using the conventional separator shown in FIG. 1, and the aeration tank 60 of the bioreactor 100 is used. The immersion separator 110 and the membrane cleaning device 200 are further installed.

The wastewater treatment system 1 using the separation membrane is a wastewater that is treated water introduced into a sedimentation tank through the sedimentation tank, a screen tank 10, a flow adjustment tank 30, an anaerobic tank 40, an anaerobic tank 50, a separation membrane It can be processed through the aerobic tank 60, the stabilization tank, and the treatment tank.

In brief, the screen tank 10 is naturally supplied with the water to be treated in the immersion tank when the water to be introduced into the immersion tank is a predetermined level or more, and the flow rate adjusting tank 30 is the screen tank ( Located at a lower level than 10), the treated water filtered by the screen tank 10 is supplied by natural drops.

In the anaerobic tank 40, when the water to be introduced into the flow regulating tank 30 is equal to or higher than a predetermined level, the raw water pump immersed the water to be treated in the flow regulating tank 30 in the flow regulating tank 30. It is supplied via a microfiltration screen.

The anaerobic tank 50 is naturally supplied with the treated water of the anaerobic tank 40 when the treated water flowing into the anaerobic tank 40 is a predetermined level or more. The mixed liquid in the anoxic tank 50 may be supplied to the anaerobic tank 40 by a transfer pump immersed in the anoxic tank 50.

The aerobic tank 60 is naturally supplied with the mixed liquid of the anoxic tank 50 when the mixed liquid stored in the anoxic tank 50 is above a predetermined level. And when the residual liquid containing the nitrate nitrogen and the sludge remaining by the solid-liquid separation by the immersion type membrane 110 immersed in the aerobic tank 60, the stabilized tank 70 naturally To feed.

When the sludge introduced from the exhalation tank 60 is a predetermined level or more, the stabilization tank 70 may be selectively supplied to the anoxic tank 50 or the sludge concentration storage tank 90 by a conveying pump immersed in the stabilization tank 70. Can be.

The treatment tank 80 receives the treated liquid separated from the liquid through the immersion separation membrane 110 immersed in the aerobic tank 60 to discharge to the outside.

At this time, the wastewater treatment system 1 using the separator is a treated water circulation pipe 261 and the chlorine dioxide tank 220, sodium hydroxide tank 230, circulating the treated water to the immersion type membrane 110, An chlorine dioxide supply pipe 221, a sodium hydroxide supply pipe 231, an organic acid supply pipe 241, and a wash water supply pipe 251, to which the organic acid tank 240 and the washing water tank 250 are connected and installed, respectively; And a control valve 300 installed in the chlorine dioxide supply pipe 221, the sodium hydroxide supply pipe 231, the organic acid supply pipe 241, and the washing water supply pipe 251 to control the supply of chlorine dioxide, sodium hydroxide, organic acid, and washing water; It may be formed to include.

In addition, the wastewater treatment system 1 using the separator is installed in connection with the control valve 300, the control unit for controlling the chlorine dioxide, sodium hydroxide, organic acid and washing water to be sequentially supplied at a predetermined interval for a predetermined time ( 400 may be formed to further include.

The wastewater treatment system 1 using the separator may further include a differential pressure gauge for measuring the filtration pressure in the surface of the immersion separator 110 or the membrane supply, wherein the controller 400 is connected to the differential pressure gauge. When the pressure of the differential pressure gauge reaches a predetermined pressure, the control valve 300 may be opened to supply chlorine dioxide, sodium hydroxide, organic acid, and washing water.

In addition, the control unit 400 opens the control valve 300 when the pressure of the differential pressure reaches a predetermined pressure, the chlorine dioxide supply pipe 221 so that chlorine dioxide, sodium hydroxide, organic acid can be sequentially supplied, The control valve 300 connected to the sodium hydroxide supply pipe 231, the organic acid supply pipe 241 and the washing water supply pipe 251 is sequentially opened one by one.

The wastewater treatment system using the separator may be washed with water between the cleaning chemicals in the order of (chlorine dioxide)-(washing water)-(organic acid)-(washing water)-(sodium hydroxide)-(washing water). Washing water can be supplied to ensure that

In one embodiment of the operation of the wastewater treatment system 1 using the separation membrane, the chlorine dioxide is supplied once a week for 20 minutes to clean the separation membrane, and then washed with washing water for 1 minute, and then the organic acid and Sodium hydroxide may be alternately supplied once every two months for 1 hour to clean the separator, and then again with washing water for 1 minute.

At this time, hydrochloric acid and nitric acid in the organic acid has a high acid concentration and affects microorganisms, and is difficult to handle, so that the citric acid or oxalic acid is preferably stored in the organic acid tank 240, and the concentration of citric acid and oxalic acid is about 1%. Is suitable.

In particular, the wastewater treatment system 1 using the separation membrane according to the present invention is chlorine dioxide is diluted to a concentration of 450 ~ 550mg / L is stored in the chlorine dioxide tank 220 does not have to provide a device for diluting the concentration separately It is easy to use.

In addition, when the wastewater treatment system 1 using the separator is diluted with chlorine dioxide, the temperature of the water to be treated in the aerobic tank 60 using the separator rises to 30-40 ° C., which is a temperature suitable for cleaning. Even without a separate heater as in the conventional wastewater treatment system, the temperature can be naturally maintained by the dilution of chlorine dioxide, thereby increasing the cleaning effect.

Accordingly, the wastewater treatment system using the separator of the present invention has the advantage that the wastewater treatment capacity can be increased by greatly improving the cleaning efficiency of the separator and allowing continuous operation of the separator without downtime, thereby greatly improving the treatment efficiency. .

In addition, by diluting the chlorine dioxide to a certain concentration, there is an advantage that it is possible to effectively clean the membrane contaminants without damaging the material of the membrane, without affecting the microorganisms.

In addition, by cleaning the membrane with citric acid and sodium hydroxide as well as chlorine dioxide, it is possible to improve the cleaning efficiency by the acid and base washing, it is possible to suppress the inorganic occlusion and organic occlusion at the same time.

In addition, by using sodium hydroxide which is naturally produced by the electrolysis of sodium chlorite as the membrane cleaning material, there is an advantage that the basic cleaning material does not need to be added separately.

It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. It goes without saying that various modifications can be made.

1: Wastewater treatment system using membrane
10: tide tank
20 screen
30: flow adjustment tank
40: anaerobic tank
50: anaerobic tank
60: aerobic tank
70: stabilization tank
80: treatment tank
90: sludge concentrate algae tank
100: bioreactor
110: immersion membrane
200: separator cleaning device
210: chlorine dioxide generator
220: chlorine dioxide tank 221: chlorine dioxide supply pipe
230: sodium hydroxide tank 231: sodium hydroxide supply pipe
240: organic acid tank 241: organic acid supply pipe
250: washing water tank 251: washing water supply pipe
261: treatment water circulation pipe
300: control valve
400:

Claims (7)

In the wastewater treatment system (1) using a separation membrane provided with a bioreactor (100) including an anaerobic tank (40), an anaerobic tank (50) and an aerobic tank (60),
The bioreactor 100
An immersion type separation membrane 110 immersed in the aerobic tank 60 so that the mixture outside the separation membrane is introduced into the separation membrane through the separation membrane pore and solid-liquid separation;
Chlorine dioxide generator 210 for electrolyzing sodium chlorite to produce chlorine dioxide diluted to a concentration of 450 ~ 550mg / L , chlorine dioxide tank 220 for storing the chlorine dioxide generated by electrolysis , Separation membrane cleaning device 200 is formed, including a sodium hydroxide tank 230, the sodium hydroxide produced by the electrolysis of sodium chlorate , the organic acid tank 240, the organic acid is stored and the washing water tank 250, the washing water is stored ;
A treated water circulation pipe 261 configured to circulate the treated water to the immersion separator 110;
The chlorine dioxide supply pipe 221, the sodium hydroxide supply pipe 231, and the organic acid supply pipe 241 to which the chlorine dioxide tank 220, the sodium hydroxide tank 230, the organic acid tank 240, and the washing water tank 250 are connected to each other. ) And washing water supply pipe 251; And
A control valve 300 installed in the chlorine dioxide supply pipe 221, the sodium hydroxide supply pipe 231, the organic acid supply pipe 241, and the washing water supply pipe 251 to control the supply of chlorine dioxide, sodium hydroxide, organic acid, and washing water; Is equipped with more,
Chlorine dioxide, sodium hydroxide, organic acid and washing water are injected into the aeration tank 60 at regular intervals for a predetermined time through the membrane cleaning device 200 to clean the immersion type membrane 110.
Waste water treatment system using a separator, characterized in that the washing water is supplied between the order of supplying chlorine dioxide, sodium hydroxide, organic acid.
delete The method of claim 1,
Waste water treatment system using the separator (1)
Separation membrane is installed in connection with the control valve 300, and further comprising a control unit 400 for adjusting to supply chlorine dioxide, sodium hydroxide, organic acid and the washing water at regular intervals for a predetermined time sequentially Wastewater treatment system using.
The method of claim 3, wherein
Waste water treatment system using the separator (1)
The differential pressure gauge for measuring the filtration pressure in the immersion membrane 110 surface or the membrane supply is further installed,
When the control unit 400 is connected to the differential pressure gauge and the pressure of the differential pressure reaches a predetermined pressure, the control valve 300 is opened to supply chlorine dioxide, sodium hydroxide, organic acid and washing water, characterized in that for supplying the separator. Wastewater Treatment System.
delete The method of claim 1,
In the organic acid tank 240
Wastewater treatment system using a separator, characterized in that citric acid or oxalic acid is stored. delete

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