KR101005422B1 - Apparatus and method for high flux membrane wastewater treatment using early stage control of membrane fouling - Google Patents

Abstract

The present invention relates to an apparatus and a method for treating sewage water, wherein the treated water is produced by immersion membranes, and membranes using initial membrane fouling control to filter with high flux by performing chemical backwashing through automatic control at the initial stage of membrane fouling of immersion membranes. Provided is a filtration sewage treatment system and treatment method. Here, the chemical backwash through automatic control calculates the instantaneous differential pressure change rate calculated from the interlayer differential pressure of the immersion membrane, and if the calculated instantaneous differential pressure change rate is constant, the filtration is continued without chemical backwashing, and if the calculated instantaneous differential pressure change rate changes rapidly It is a method of backwashing drugs to remove initial membrane contaminants. According to the present invention, by effectively controlling membrane fouling at an early stage, the filtration performance can be improved, and through this, the amount of membrane used and additional equipment required for membrane filtration can be reduced to 1/2.

Membrane Separation, Membrane Contamination, Chemical Backwash, Initial Membrane Control, Instantaneous Pressure Change Rate, High Flux

Description

Application and method for high flux membrane wastewater treatment using early stage control of membrane fouling

The present invention relates to a wastewater treatment apparatus and a treatment method, and more particularly, to a high flux membrane filtration wastewater treatment apparatus and treatment method using an initial membrane contamination control that can efficiently control membrane contamination at an early stage to improve filtration performance. It is about.

Membrane filtration activated sludge method can achieve a stable treated water quality by completely performing solid-liquid separation with a membrane and maintaining a high concentration of microorganisms in a bioreactor, can significantly reduce the volume of the bioreactor and can be operated automatically.

However, despite these various advantages, the commercialization is difficult due to excessive initial investment and energy costs for membrane use and membrane cleaning and replacement due to contamination of the membrane. Therefore, to minimize the use of membranes, efforts are being made to increase the amount of water produced per membrane area (flux, ℓ / ㎡ / h), but membrane fouling rate increases with increasing flux. There is a disadvantage to operate below the so-called critical flux. Most membrane filtration activated sludge process using hollow fiber membrane of PVDF material adopts flux of 20ℓ / ㎡ / h to maintain stable filtration performance.

When membrane filtration is carried out below the critical flux, contamination of the membrane proceeds slowly and the filtration performance remains stable. However, when a certain point is reached, membrane fouling progresses rapidly, resulting in a drastic change in filtration performance. Therefore, in order to prevent such changes, maintenance cleaning is periodically performed by adding chemicals during backwashing, but for this purpose, a separate chemical backwash pump is used, and in this case, membrane filtration is not performed beyond the critical flux. I can't.

As a solution to this problem, an object of the present invention is to effectively remove membrane fouling components at the early stage of membrane fouling to operate high flux membrane filtration above the critical flux.

Another object of the present invention is to filter the membrane using a high flux of 40 l / ㎡ / hr, which is twice as high as the conventional membrane filtration activated sludge method, and the amount of auxiliary equipment such as valve, suction pump, blower, etc. required for membrane filtration. To reduce to half.

In order to achieve these objects, the present invention provides a sewage treatment apparatus including a membrane filtration activated sludge device provided with an immersion membrane and a filtration backwash device. The filtration backwashing device includes a treated water storage tank, a backwash chemical pump, an automatic valve, a pressure gauge, and an automatic control device. The treated water storage tank stores the treated water filtered by the immersion membrane during suction filtration. The backwashing chemical pump supplies the backwashing chemical to the backwashing line at the time of chemical backwashing. The automatic valve adjusts the flow direction of the treated water between the immersion membrane and the treated water storage tank. The pressure gauge measures the interlayer differential pressure of the immersion membrane. And the automatic control device calculates the instantaneous differential pressure change rate using the measured intermembrane differential pressure, and if the calculated instantaneous differential pressure change rate is constant, continues filtration, and if the calculated instantaneous differential pressure change rate changes abruptly, the automatic valve The control to send the treated water of the treated water storage tank to the immersion membrane, the backwashing chemicals mixed with the treated water to perform the chemical backwash to send to the immersion membrane.

The present invention provides a wastewater treatment method of the high flux membrane filtration sewage treatment apparatus. The wastewater treatment method according to the present invention comprises the steps of: filtering the contaminants by the immersion membrane; calculating the instantaneous differential pressure change rate calculated from the interlayer differential pressure of the immersion membrane; and if the calculated instantaneous differential pressure change rate is constant, filtering is performed. The step of continuing, and if the calculated instantaneous differential pressure change rate is suddenly changed, by controlling the automatic valve to send the treated water of the treated water storage tank to the immersion membrane, by mixing the backwash chemical to the treated water And implanting into the immersion membrane and allowing it to settle for a period of time to dissolve and remove the membrane fouling material.

The high flux membrane filtration sewage water treatment method using the initial membrane fouling control of the present invention can remove the membrane fouling component at an early stage and thus perform the high flux membrane filtration, thus requiring a pressure gauge, a suction pump, a blower, a valve required for membrane use and membrane filtration. Reduce the usage of the back to 1/2.

In addition, it is easy and economical to install and maintain because the same pump is used without separately installing a filtration pump that sucks during filtration and a backwashing pump that supplies a backwashing solution for chemical backwashing.

Hereinafter, the present invention will be described in detail by the accompanying drawings.

1 is a view showing a schematic configuration of a high flux membrane filtration sewage treatment apparatus using the initial membrane fouling control of the present invention, the sewage treatment apparatus of the present invention is an immersion type membrane separation activated sludge apparatus 100 and filtration backwash apparatus 200 It is configured to include).

The submerged membrane filtration activated sludge device 100 is provided with an anaerobic tank 111, an anaerobic tank 112, and a membrane separation aeration tank 113. Raw water introduced into the anaerobic tank 111 is introduced into the membrane separation aeration tank 113 through the anaerobic tank 112. In addition, the sludge in the membrane separation aeration tank 113 is conveyed to the anaerobic tank 112 by the first sludge conveying apparatus 130, and the sludge in the anoxic tank 112 is transferred to the anaerobic tank 111 by the second sludge conveying apparatus 140. Is returned.

In the anaerobic tank 111, the phosphorus component is released from the microorganism. In the oxygen-free tank 112, nitrate nitrogen is reduced to nitrogen gas to remove nitrogen. In the membrane separation aeration tank 113, ammonia nitrogen in the influent is oxidized to nitrate nitrogen, phosphorus components in the influent are excessively ingested by the microorganism, and organic components in the influent are oxidized and removed by the microorganism. Phosphorus component excessively ingested by the microorganisms in the membrane separation aeration tank 113 is included in and removed from the microorganisms in the sludge discharged by the sludge discharge pump 150.

The sludge discharge pump 150 for intermittently discharging the sludge is installed at the outer lower portion of the membrane separation exhalation tank 113. Inside the membrane separation aeration tank 113, an immersion type membrane 114 for filtering solids during filtration operation is installed. In addition, in order to prevent the solids filtered out by the filtration operation from being attached to the immersion membrane 114, the first diffuser device 115 is installed below the immersion membrane 114. In order to supply oxygen necessary for microbial growth in the membrane separation aeration tank 113, a second acid generator 116 is installed. An air supply device 120 is installed outside the membrane separation exhalation tank 113 to supply air to the first and second air dispersing devices 115 and 116.

The filtration backwash device 200 includes a filtration backwash pump 430, a pressure gauge 260, and an automatic control device 250. And there is an automatic valve (210, 220, 230, 240), the treated water storage tank 310 and the backwash chemical pump 420, which controls the filtration and chemical backwash direction, the backwash chemical tank backwash chemical tank (410) )

The filtration backwash pump 430 sucks the treated water during the filtration operation of the immersion membrane 114 and sends the treated water to the treated water storage tank 310. During the chemical backwash, the filtered backwash pump 430 immerses the treated water in the treated water storage tank 310. Injection into the membrane 114. In the conventional membrane filtration activated sludge method, a filtration pump suctioned during filtration and a chemical backwash pump for backwashing are separately installed, but in the present invention, the filtration backwash pump 430 is used together for filtration and chemical backwashing.

The pressure gauge 260 measures the interlayer differential pressure of the membrane, and the automatic control unit 250 receives the interlayer differential pressure measured by the pressure gauge 260 to calculate the instantaneous differential pressure change rate and backwash the chemical pump at the time of filtration and at the backwash of the chemical. 420 and the function of controlling the operation and opening and closing of the automatic valve (210, 220, 230, 240). Automatic valve 210, 220, 230, 240 is composed of four. The first automatic valve 210 controls the flow to transfer the treated water to the filtration backwash pump 430 during filtration. The second automatic valve 220 controls the flow to be transferred to the treated water storage tank 310 through the filtration backwash pump 430 during filtration. The third automatic valve 230 controls the flow so that the treated water stored in the treated water storage tank 310 is transferred to the filtered backwash pump 430 during chemical backwashing. In addition, the fourth automatic valve 240 controls the flow such that the treated water stored in the treated water storage tank 310 is supplied to the immersion membrane 114 through the filtered backwash pump 430 during the chemical backwash.

Hereinafter, the membrane filtration sewage treatment method using the initial membrane contamination control according to the present invention will be described with reference to FIGS.

First, the immersion membrane 114 undergoes a filtration step (S11) of producing treated water. That is, Figure 2 shows the filtration step of the high flux membrane filtration sewage treatment apparatus using the initial membrane fouling control, the first automatic valve 210 and the second automatic valve 220 is opened, the third automatic valve 230 and The fourth automatic valve 240 is closed to form the filtration line 300.

Raw water introduced into the anaerobic tank 111 of the submerged membrane filtration activated sludge device 100 passes through the anaerobic tank 112 and flows into the membrane separation aeration tank 113. The sludge in the membrane separation aeration tank 113 is conveyed to the anaerobic tank 112 by the first sludge conveying apparatus 130, and the sludge in the anoxic tank 112 is conveyed to the anaerobic tank 111 by the second sludge conveying apparatus 140. do.

In addition, the solids in the membrane separation aeration tank 113 are filtered from the surface of the immersion membrane 114 during filtration, and only purified water is introduced into the separation membrane. At this time, the solid material adhered to the surface of the immersion membrane 114 is shaken while the air supplied from the air supply device 120 rises in the form of air bubbles through the first diffuser device 115 installed below the immersion membrane 114. Removed.

Next, the instantaneous differential pressure change rate calculated from the interlayer differential pressure of the immersion type film 114 is calculated (S12).

As a result of the calculation of step S12, if the rate of change of the instantaneous differential pressure is constant, step S11, which is a filtration step, is continuously performed.

On the other hand, if the instantaneous differential pressure change rate calculated from the interlayer differential pressure as a result of the comparison of step S12, the immersion membrane 114 is backwashed with the chemical (S14). Here, the chemical backwashing is performed by the automatic control device 250 receiving the interlayer differential pressure sensed by the pressure gauge 260 to calculate the instantaneous differential pressure change rate (ΔP / ΔT), that is, the membrane fouling rate, and thus, each automatic valve 210, 220, 230, By controlling the opening and closing of 240, the backwashing solution in which the treated water and the backwashing chemical are mixed is sent to the immersion membrane 114 in the reverse direction of the filtration operation.

Figure 3 shows the chemical backwashing step of the high flux membrane filtration sewage treatment apparatus using the initial membrane fouling control of the present invention, the first automatic valve 210 and the second automatic valve 220 is closed, the third automatic valve 230 and the fourth automatic valve 240 is opened to form a back washing line 400.

The filtered water of the treated water storage tank 310 is supplied to the backwashing line 400 by the filtration backwash pump 430, which is mixed with the backwashing chemical injected through the backwashing chemical pump 420 at a predetermined position. do. The mixed backwashing solution is injected into the submerged membrane 114 for a predetermined time and backwashed to remove the reversible membrane fouling material attached to the surface or inside of the separator. After backwashing, all automatic valves 210, 220, 230, and 240 are closed by the signal of the automatic control device 250, and the filtration backwash pump 430 is also stopped and backwashed in the immersion membrane 114. It is allowed to stand for a while with the solution filled. This is to remove and remove irreversible membrane contaminants by chemical action of backwash solution.

By backwashing such chemicals, membrane fouling components can be removed within a short time with chemicals of low concentration than conventional chemical cleaning information, and stable membrane filtration operation can be continued even at high flux (40 L / m 2 / hr).

As the backwash chemical, any chemical may be used as long as it is effective for cleaning the immersion membrane 114. Preferably, sodium hypochlorite (NaOCl) is used. This is because it is known to be economical and effective for cleaning the immersion type membrane 114 in the membrane filtration activated sludge method.

When the series of chemical backwash is finished, the filtration performance of the immersion membrane 114 is restored, and the filtration operation is resumed (S11).

The amount of water treated during chemical backwashing varies depending on the shape and size of the immersion membrane 114, and 10-40 L per membrane module is used, and the backwashing solution mixed with the treated water and backwashing chemical is sodium hypochlorite 0.01 ~. Conduct at a concentration of 0.06%. If the concentration of the backwashing solution is less than 0.01%, the cleaning effect is lowered. If the concentration of the backwashing solution is more than 0.06%, the economic burden is increased due to the increase in the amount of the backwashing solution.

In case of chemical backwashing, the backwashing solution injection time is 2 ~ 5 minutes, the backwashing flux is the same 40ℓ / ㎡ / hr as the filtration time, and the settling time is 30 ~ 60 minutes. Do.

The present invention is not limited by the embodiments and drawings described herein, and various modifications may be made by those skilled in the art to which the present invention pertains.

In the present invention, the membrane is returned to the initial state by chemical backwashing at the beginning of membrane fouling, so that the filtration efficiency is improved to allow operation at a high flux of 40 l / m 2 / hr or more.

In addition, the filtration backwash pump can be used for both filtration and chemical backwash, and the backwashing agent and the treated water can be mixed in the backwash line, thereby eliminating the need for a separate backwash solution tank to improve the economics of the apparatus. have.

1 is a view showing a schematic configuration of a high flux membrane filtration sewage treatment apparatus using the initial membrane fouling control of the present invention

Figure 2 is a view showing the filtration step of the high flux membrane filtration sewage treatment apparatus using the initial membrane fouling control of the present invention

Figure 3 is a diagram showing the chemical backwashing step of the high flux membrane filtration sewage treatment apparatus using the initial membrane fouling control of the present invention

Figure 4 is a flow chart showing a high flux membrane filtration sewage treatment method using the initial membrane fouling control according to an embodiment of the present invention

** Description of symbols for the main parts of the drawing **

100: activated sludge device 110: agitator

111: anaerobic tank 112: anaerobic tank

113: membrane separation aerobic tank 114: immersion membrane

115: first mountain device 116: second mountain device

120: air supply device 130: first sludge conveying device

140: second sludge conveying device 150: sludge discharge pump

200: filtration backwash device 210: first automatic valve

220: second automatic valve 230: third automatic valve

240: fourth automatic valve 250: automatic control device

260: pressure gauge 300: filtration line

310: treated water storage tank 400: backwash line

410: backwash chemical tank 420: backwash chemical pump

430: filtration backwash pump

Claims (5)

In the sewage treatment apparatus comprising a membrane filtration activated sludge device with an immersion membrane and a filtration backwash device, The filtration backwash device, A treated water storage tank storing the treated water filtered by the immersion membrane during suction filtration; A backwashing chemical pump for supplying backwashing chemicals to the backwashing line at the time of chemical backwashing; An automatic valve controlling a flow direction of the treated water between the immersion membrane and the treated water storage tank; A pressure gauge for measuring the interlayer differential pressure of the immersion membrane; The instantaneous differential pressure change rate is calculated using the measured interlayer differential pressure. If the calculated instantaneous differential pressure change rate is constant, the filtration is continued. If the calculated instantaneous differential pressure change rate is rapidly changed, the automatic valve is controlled to control the treated water. And an automatic control device for sending the treated water from the storage tank to the immersion membrane, and mixing the backwashing chemical with the treated water to perform the reverse chemical washing to the immersion membrane. When the immersion type membrane is a hollow fiber membrane of PVDF material, high flux membrane filtration sewage and wastewater treatment apparatus using an initial membrane contamination control, characterized in that the filtration with high flux (40ℓ / ㎡ / h). The method of claim 1, A high flux membrane filtration sewage water treatment system using initial membrane fouling control, characterized in that the concentration of sodium hypochlorite (NaOCl) in the backwashing solution mixed with the treated water and the backwashing chemical is 0.01 to 0.06%. delete In the wastewater treatment method of the membrane filtration sewage treatment apparatus according to claim 1, Filtering contaminants by the immersion membrane; Calculating an instantaneous differential pressure change rate calculated from the interlayer differential pressure of the immersion type film; If the calculated instantaneous differential pressure change rate is constant, continuing filtration; When the calculated instantaneous differential pressure change rate changes rapidly, the automatic valve is controlled to send the treated water from the treated water storage tank to the immersion membrane, and the backwashing chemical is mixed with the treated water to inject the immersion membrane. It includes a step of standing for a predetermined time to dissolve and remove the membrane contaminant, When the immersion membrane is a hollow fiber membrane of PVDF material, high flux membrane filtration sewage water treatment method using the initial membrane fouling control, characterized in that the filtration with high flux (40ℓ / ㎡ / h). The method of claim 4, wherein The chemical backwashing step may be performed by mixing the backwashing chemical with the treated water and injecting the submerged membrane with high flux as in the case of filtration with the submerged membrane for 2 to 5 minutes, and dissolving and removing the membrane contaminant. High flux membrane filtration sewage treatment method using the initial membrane fouling control, characterized in that it comprises a step of standing for ~ 60 minutes.

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