KR102521662B1 - Thickening system for low concentration of sludge generated in water treatment process - Google Patents

Abstract

Disclosed is a method for minimizing a separator required when sludge in a low concentration is thickened through the separator. The method is used in thickening sludge using a separator in a thickening system of sludge generated in a water treatment process. The present invention provides a sludge thickening system, which is a thickening system of sludge generated in a water treatment process, and comprises: a first separator tank which has a first separator therein, has sludge introduced therein and thickens the sludge through the first separator to discharge or return treated water to an introduction facility; a buffer tank which stores sludge transferred from the first separator tank; and a second separator tank which has a second separator therein, has the sludge introduced from the buffer tank to thicken the sludge through the second separator, discharges or returns treated water to the introduction facility, and draws the thickened sludge to the outside.

Description

Thickening system for low concentration of sludge generated in water treatment process}

The present invention relates to a sludge thickening system, and more particularly, to a low-concentration sludge thickening system generated in a water treatment process.

A technique for efficiently concentrating sludge inevitably generated in a biological treatment process in sewage and sewage treatment and stably securing the quality of treated water separated from solids has been disclosed.

The sludge generated in the biological treatment process is concentrated and stabilized to secure the inlet solids concentration required for each dewatering facility. 2 to 3% (wt/v), 0.4 to 0.8% (wt/v) for screw press dehydrators, 2 to 3% (wt/v) for belt press dehydrators, and 2 to 3% (wt/v) for centrifugal dehydrators. 0.8 to 2% (wt/v).

In general, in the water treatment process excluding the MBR (Membrane Bio Reactor) process, the solids concentration in the aerobic reactor is around 3,000 mg/L (0.3%), and the solids concentration in the surplus sludge in the secondary settling tank is 6,000 to 10,000 mg/L (0.6 to 1%) ), the drawn sludge must be adjusted to the concentration of the inlet sludge exemplified above through the thickening and stabilization process in order to properly operate the dehydrator.

At this time, in order to adjust the concentration of the inflow sludge suitable for the dehydrator, it is necessary to adjust the amount of the surplus sludge entering the final dehydrator to about 10% through the thickening and stabilization process. Since it is transported to the inlet in the form of return water, it increases by about 2% compared to the design flow rate, which causes a decrease in the efficiency of the water treatment process.

On the other hand, in order to prevent contamination of the filter when separating the liquid contained in the sludge, the higher the concentration of the sludge, the lower the amount of treated water (permeation flux) produced by the separator. There is a problem that excessive separation membranes must be used when drawing low-concentration sludge using a separation membrane, such as in an aeration tank (aeration tank).

[Prior patent literature]

- Korean Registered Patent No. 10-0401720 (registered on October 1, 2003)

The present invention is to provide a sludge concentration system using a separation membrane in a sludge concentration system generated in a water treatment process, which can minimize the separation membrane required when low-concentration sludge is concentrated using a separation membrane.

In order to solve the above problems, the present invention is a system for concentrating sludge generated in a water treatment process, a first separation membrane is provided therein, the sludge is introduced and the sludge is concentrated through the first separation membrane to discharge treated water or a first membrane tank returned to the inflow facility; a buffer tank for storing the sludge transported from the first membrane tank; And a second separation membrane is provided therein, the sludge is introduced from the buffer tank, the sludge is concentrated through the second separation membrane, the treated water is returned to the discharge or inflow facility, and the concentrated sludge is drawn out of the system. It provides a sludge thickening system comprising a; 2 membrane tank.

In addition, the inflow sludge provides a sludge thickening system, characterized in that the concentration is a low concentration of 5,000 mg / L or less.

In addition, it is concentrated to a concentration of 10,000 to 20,000 mg / L in the first membrane tank, and concentrated to a concentration of more than 20,000 mg / L and less than 30,000 mg / L in the second membrane tank.

In addition, the sludge concentrating system is characterized in that an aeration tube is installed under the first membrane tank, the buffer tank, and the second membrane tank, respectively.

According to the present invention, a sludge concentrating system using a separation membrane is provided with a first separation membrane tank and a second separation membrane tank equipped with a separation membrane therein, and a buffer tank between each membrane tank, so that the first separation membrane tank mediates the buffer tank The low-concentration sludge introduced into the membrane tank is continuously primary concentrated, and in the second membrane tank, the primary concentrated sludge introduced from the buffer tank is secondaryly concentrated to the target concentration in consideration of the dewatering process in a batch manner, thereby achieving continuous and batchwise When low-concentration sludge is drawn out using a separation membrane through a mixing method, it is possible to provide a sludge concentrating system capable of minimizing excessive separation membranes.

1 is a block diagram showing a sludge thickening system according to an embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In describing the present invention, if it is determined that a detailed description of related known technologies may obscure the gist of the present invention, the detailed description will be omitted. In order to clearly describe the present invention in the drawings, parts irrelevant to the description have been omitted, similar reference numerals have been assigned to similar parts throughout the specification, and throughout the specification, certain parts can be said to "include" certain components. When, this means that other components may be further included, rather than excluding other components, unless otherwise stated.

1 is a block diagram showing a sludge thickening system according to an embodiment of the present invention.

Referring to FIG. 1 , a sludge concentration system 100 according to an embodiment of the present invention includes a first membrane tank 110 , a buffer tank 120 and a second membrane tank 130 .

The first separation membrane tank 110 is a tank into which excess sludge generated in the water treatment process is introduced, and has a first separation membrane 111 therein so that the introduced sludge is concentrated through the first separation membrane 111 . The concentrated sludge is transferred to the buffer tank 120 through the first sludge transfer pump 112, and the treated water from the first separation membrane 110 is discharged or introduced through the first suction pump 113. may be released outside.

In the present invention, the water treatment process is not particularly limited as long as it is a water treatment process that generates excess sludge, and may be, for example, a biological treatment process. can be made

The concentration of the inflowing surplus sludge may be in the form of relatively low-concentration raw water considering the number of first separators 111 used, preferably 5,000 mg / L or less, more preferably 1,000 to 4,000 mg It can be /L. Considering such a low-concentration raw water, it is preferable that the water treatment process generating excess sludge in the present invention is an aeration tank (aeration tank).

In addition, in the present invention, the first separation membrane 111 is not particularly limited in its type and shape, but considering the concentration of influent raw water, it is preferable to apply a submerged microfiltration membrane (MF).

In general, in sludge concentration, sludge concentration for dehydration is secured through several steps, but sludge concentration using a separation membrane can be simplified with one separation membrane equipment process. However, the process of thickening and stabilizing the sludge to secure the sludge concentration for dehydration causes odors because there is no aerobic condition, and the inflow concentration is increased by about 5% compared to the inflow concentration due to the high concentration of the return water.

In the present invention, the first air diffuser 114 is provided at the bottom of the first separation membrane tank 110 so that air can be supplied through the first blower 115. It is possible to minimize the generation of odor, minimize the production of treated water (reflux water), and reduce the load of inflow water when returning it to the inlet facility because the concentration of treated water (reflux water) is very low. In particular, suspended solids (SS) are rarely generated, and it is possible to secure stable water quality by reducing the inflow load by treated water (return water) by minimizing phosphorus release. Here, a second diffuser pipe 121 and a third diffuser pipe 131 are installed at the bottom of not only the first separation membrane tank 110, but also the buffer tank 120 and the second membrane tank 130, which will be described later, respectively. Of course, it is possible to supply air through the second blower 122 and the third blower 132.

In addition, since the concentration of inflow sludge can be adjusted according to the operation time of the first membrane tank 110 and the second membrane tank 130 to be described later, the efficiency of the dehydrator can be maximized by securing an inflow concentration suitable for all dehydrators.

Here, in the case of operating only the first membrane tank 110 equipped with the first separation membrane 111 during sludge concentration, it is difficult to simultaneously perform the sludge concentration, discharge of treated water, and the process of drawing concentrated sludge, but in the present invention, sludge concentration and means for allowing the drawing process to be performed simultaneously.

That is, in the present invention, the buffer tank 120 is provided to store the sludge transferred from the first membrane tank 110, and the sludge introduced from the buffer tank 120 through the second sludge transfer pump 123 is transferred to the second Continuous operation in which condensation in the first separation membrane tank 110 and drawing in the second separation membrane tank 130 are performed simultaneously by providing the second separation membrane tank 130 for concentrating through the separation membrane 133 and drawing it out of the system. make this possible

Specifically, the buffer tank 120 is filled with sludge transferred from the first membrane tank 110 by the first sludge transfer pump 112, and the second membrane tank 130 is filled with the buffer tank 120. Since the medium is separated, the sludge that has reached the target concentration can be drawn out of the system in the second membrane tank 130 independently of the concentration process in the first membrane tank 110, Continuous operation that allows raw water inflow, concentration in the first membrane tank 111, sludge transfer from the first membrane tank 110 to the buffer tank 120, and sludge drawing from the second membrane tank 130 to be simultaneously performed possible. Sludge is drawn from the second membrane tank 130 by means of a concentrated sludge draw pump 134 .

Here, in the second membrane tank 130, since it is necessary to secure the sludge concentration for the subsequent dehydration process, it is difficult to simultaneously perform concentration and sludge drawing through the second membrane 133, so the second membrane tank 130 itself is batchwise Therefore, the sludge thickening system according to the present invention will be considered as a system in which continuous and batch mixing methods are applied.

In the present invention, the buffer tank 120 serves to store the sludge transferred from the first membrane tank 110 and transfer the sludge to the second membrane tank 130 according to the concentration state of the second membrane tank 130 do

In the present invention, the second separation membrane tank 130 is a tank into which sludge primarily concentrated from the buffer tank 120 is introduced, and a second separation membrane 133 is provided therein so that the inflowed sludge flows into the second separation membrane 133. ) to be concentrated. The concentrated sludge is drawn into the dewatering facility through the concentrated sludge draw pump 134, and the treated water treated from the second separation membrane 130 is discharged through the second suction pump 135. there is.

The type and shape of the second separation membrane 133 are not particularly limited, but considering the concentration of influent raw water, it is preferable to apply a submerged microfiltration membrane (MF).

Here, in the second membrane tank 130, the sludge introduced from the buffer tank 120 is at a concentration of more than 20,000 mg/L and less than 30,000 mg/L, preferably 23,000 to 27,000 mg/L, which is a target concentration considering the dehydration process In contrast, in the first separation membrane tank 110, raw water introduced at a low concentration may be primarily concentrated to a concentration of 10,000 to 20,000 mg/L, preferably 13,000 to 17,000 mg/L. Therefore, in the second membrane tank 130, the firstly concentrated medium concentration level is received and secondarily concentrated to a high concentration level to secure the sludge concentration considering dehydration. At this time, the second membrane tank 130 is required The number of second separation membranes 133 to be used can be significantly reduced compared to the case of operating only the first separation membrane tank 110 .

Specifically, if the sludge withdrawal amount is 90 kg/d, when the membrane area required for concentration at a high concentration of 25,000 mg/L is 72 m2 using a membrane under the condition of a high concentration of 10,000 mg/L, 2,500 mg In the condition of inflow at a low concentration of /L, a separation membrane of 4 times the normal area, that is, 288 m2, is required. In this case, as in the present invention, when the primary concentration at a certain level of medium concentration in the first separation membrane tank 110 and the secondary concentration at a certain level of high concentration in the second separation membrane tank 130 are performed, for example, the sludge withdrawal amount is 90 In the case of kg/d, for the low-concentration sludge of 2,500 mg/L, a membrane of about 144 m2 is required for primary concentration at a medium concentration of 15,000 mg/L in the first membrane tank (110), and the second membrane tank (130 ), when the medium-concentration sludge is concentrated to a high concentration of 25,000 mg/L, a separation membrane of about 72 m2 is required, a total of 216 m2 of separation membrane, which is about 25% of the separation membrane requirement compared to the case of using a single membrane tank will have a reducing effect.

On the other hand, in the sludge concentration system according to the present invention, the time and time for concentrating the sludge in the first separation membrane tank 110 and the second separation membrane tank 130 in which the first separation membrane 111 and the second separation membrane 133 are installed 2 No dehydration process is required during the time when the membrane tank 130 is emptied and the sludge is concentrated to a concentration that allows the dehydration process. .

Example of designing a concentration system using a separation membrane

For example, when raw water with a BOD of 200 mg/L flows in from a treatment facility with a capacity of 1,000 ㎥/day, the amount of sludge withdrawn is about 90 kg/day, and 0.25% aerobic sludge is directly drawn from the bioreactor to raise the sludge concentration to 2.5%. In the case of concentration, the concentration facility using a separation membrane is as follows, and the expected results of the operation of the concentration system are shown in Table 1 below.

[Enrichment facility]

- 1st membrane tank: 3.0 mW × 3.0 mL × 2.0 mHe

- Buffer Tank: 3.0 mW × 3.0 mL × 2.0 mHe

- Second membrane tank: 3.0 mW × 3.0 mL × 2.0 mHe

- Membrane facility: 1 meal

- With an effective capacity of 18 ㎥ in the membrane tank, the sludge dewatering process is operated once every 5 days, and when the capacity of the dehydration facility is 5 ㎥/h, it is completed after about 4 to 5 hours of operation.

- Depending on the capacity of the membrane tank, the operating cycle of the dehydration process can be changed

division 1 day 2 days 3 days 4 days 5 days 6 days 7 days 8 days 9 days 10 days 11 days 12 days 13th 14 days 15th 16th 0.25% sludge injection (kg/day) 90 180 270 90 180 90 180 270 90 180 90 180 270 90 180 90 1st separation membrane crude sludge concentration (%) 0.5 1.0 1.5 0.5 1.0 0.5 1.0 1.5 0.5 1.0 0.5 1.0 1.5 0.5 1.0 0.5 1st production number generated (㎥/day) 18 36 36 18 36 18 36 36 18 36 18 36 36 18 36 18 Buffer Tank 0 0 0 0 18 9 0 18 0 18 9 0 18 0 18 9 Sludge amount (kg/day) 0 0 270 270 270 360 450 450 270 270 360 450 450 270 270 360 2nd membrane crude sludge concentration (%) 0 0 1.5 1.5 1.5 2.0 2.5 2.5 1.5 1.5 2.0 2.5 2.5 1.5 1.5 2.0 Generation of secondary production (㎥/day) 0 0 0 0 0 9 9 0 0 0 9 9 0 0 0 9 Operation of dehydrator × × × × × × × ◎ × × × × ◎ × × × Total number of production (㎥/day) 18 36 36 18 36 27 45 36 18 36 27 45 36 18 36 27

Referring to Table 1, the operation of the dehydrator is carried out after the first 8 days (the dewatering process is unnecessary for about 8 days when restarting after the entire amount of the membrane tank and buffer tank is drawn), and then 5 days later, it can be seen that the number of dehydration processes is greatly reduced. there is. Produced water (separation membrane treated water) can be generated (0.75~1.88㎥/h production) for 24 hours, and is transferred to discharge facilities (final discharge) or inflow facilities (raw water distribution tank, flow control tank) depending on the conditions of the treatment facility. can be designed to be possible.

In addition, the concentrated sludge concentration can be adjusted according to the operation time of the membrane tank, so that the inflow concentration suitable for all dehydrators can be secured, and the efficiency of the dewatering facility can be maximized.

In the above, preferred embodiments of the present invention have been described in detail with reference to the drawings. The description of the present invention is for illustrative purposes, and those skilled in the art will understand that it can be easily modified into other specific forms without changing the technical spirit or essential features of the present invention.

Therefore, the scope of the present invention is indicated by the following claims rather than the above detailed description, and all changes or modifications derived from the meaning, scope and equivalent concept of the claims are included in the scope of the present invention. should be interpreted

100: sludge concentration system 110: first membrane tank
111: first separator 112: first sludge transfer pump
113: first suction pump 114: first diffuser
115: first blower 120: buffer tank
121: second diffuser 122: second blower
123: second sludge transfer pump 130: second membrane tank
131: 3rd diffuser 132: 3rd blower
133: second separator 134: concentrated sludge draw pump
135: second suction pump 140: screen

Claims (4)

As a sludge thickening system generated in the water treatment process,
a first separation membrane tank having a first separation membrane therein, in which the sludge is introduced, and concentrating the sludge through the first separation membrane to return the treated water to a discharge or inflow facility;
a buffer tank for storing the sludge transported from the first membrane tank; and
A second separation membrane is provided inside, sludge is introduced from the buffer tank, the sludge is concentrated through the second separation membrane, the treated water is returned to the discharge or inflow facility, and the concentrated sludge is drawn out of the system. Separation membrane tank;
Including,
The sludge concentration system, characterized in that the concentration of the sludge flowing into the first membrane tank is a low concentration of 1,000 to 4,000 mg / L. delete According to claim 1,
Concentrating to a concentration of 10,000 to 20,000 mg / L in the first membrane tank, and concentrating to a concentration of more than 20,000 mg / L and less than 30,000 mg / L in the second membrane tank. Sludge concentration system. According to claim 1,
The sludge concentrating system, characterized in that a diffuser is installed in the lower part of the first membrane tank, the lower part of the buffer tank, and the lower part of the second membrane tank.

Images