JP2005193125A - Waste sludge treatment method of water purification plant - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a waste sludge treatment method of a water purification plant capable of treating sludge at a low cost by miniaturizing a sedimentation basin waste sludge storage tank for temporarily reserving sludge until the sludge is fed to a sludge treatment apparatus and the sludge treatment apparatus. <P>SOLUTION: In the waste sludge treatment method of the water purification plant constituted so that raw water is subjected to sedimentation/separation treatment in a sedimentation basin 1 and the supernatant water of the sedimentation basin 1 is filtered and purified in a filter basin 2 while the separated sedimented sludge is temporarily reserved in the sedimentation basin waste sludge storage tank 4 until feeding to the sludge treatment apparatus, backwashing water used for backwashing the filter basin 2 is subjected to sedimentation/separation treatment in a backwashing drain tank 5 and the separated sedimented sludge of high concentration is fed to the sedimentation basin waste sludge storage tank 4 while discharging the supernatant water of the drain tank 5. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a wastewater treatment method for a water purification plant that purifies raw water taken from river water, dams, and groundwater by precipitation separation and filtration.

  The conventional wastewater treatment facility has a sedimentation pond that stores raw water and settles sludge in the raw water, and a filtration pond that filters the supernatant water from which sludge has been removed. In general, there is a settling basin sludge storage tank that temporarily stores backwash water and sludge in the settling pond, and a sludge treatment device that concentrates and dehydrates the sludge in the settling pond drainage sludge tank. It is.

  By the way, since the backwash water in the filtration pond is drained in a large amount in a short time with a low concentration, it is necessary to enlarge the sedimentation pond waste mud storage tank, and there is a problem that costs for civil engineering work are increased. Moreover, since the concentration of sludge stored by lowering backwash water with low concentration is drained directly into the sedimentation basin sludge storage tank, it is necessary to enhance the sludge treatment equipment accordingly, which is inefficient and There was also a problem that would increase the size.

On the other hand, Patent Document 1 discloses a technique in which backwash water is filtered by a membrane filtration device and only the remaining concentrated sludge is sent to a sludge treatment device. However, since the membrane filtration device is expensive, there is a problem that a large amount of cost is required for processing.
Japanese Patent Laid-Open No. 11-19696

  The problem to be solved by the present invention is to solve these conventional problems and reduce the size of the sedimentation pond waste mud storage tank and the sludge treatment apparatus that temporarily store sludge until the sludge is sent to the sludge treatment apparatus. It is to provide a wastewater treatment method for a water purification plant that can be efficiently treated at a cost.

The configuration of the present invention that solves this problem is as follows.
1) The raw water is separated and settled in a sedimentation basin, and the supernatant water is filtered and purified in a filtration pond, and the separated sludge is temporarily stored in the sedimentation pond waste mud storage tank until it is sent to the sludge treatment unit. In the field wastewater treatment method, the backwash water obtained by backwashing the filtration basin was separated by precipitation in the backwash drainage tank, and the separated high-concentration sedimentation sludge was sent to the sedimentation pond wastewater storage tank. 2) The sludge treatment method of the water purification plant according to the above 1), wherein the sludge treatment device concentrates, condenses and dehydrates the sludge in the sedimentation pond waste mud storage tank. 3) The sludge treatment method of the water purification plant according to 1) or 2) wherein the supernatant water of the backwash drainage tank is filtered and discharged 4) The wastewater of the water purification plant according to any one of 1) to 3) above The treatment method is in the sludge treatment method of a water purification plant that is used for waterworks.

  According to the present invention, the backwash water in the filtration pond is precipitated and separated in the backwash drainage tank, and the supernatant water is filtered and discharged. Therefore, only the precipitated high concentration and small amount of sludge is settled in the sedimentation pond waste mud storage tank. It is possible to reduce the size of the sedimentation basin mud storage tank and drastically reduce the construction work costs associated with the installation, as well as to reduce the size of the sludge treatment device, thereby enabling efficient treatment at low cost.

  As the sludge treatment apparatus of the present invention, a known sludge treatment apparatus such as one that concentrates and agglomerates sludge in a sedimentation pond waste mud storage tank to dehydrate it is used. A filter press is most effective as the dehydrator, but other centrifugal separators (decanters), vacuum dehydrators, roll dehydrators, and the like can also be used. The supernatant water of the backwash drain is further filtered and discharged as necessary. Embodiments of the present invention will be specifically described below with reference to the drawings.

  FIG. 1 is an explanatory diagram of a wastewater treatment facility of a water purification plant according to an embodiment, and FIG. 2 is a chart showing steps of a backwash drainage tank according to the embodiment. In the figure, 1 is a sedimentation basin, 2 is a filtration pond, 3 is a drainage pit, 4 is a sedimentation basin mud storage tank, 4a is an underwater wastewater pump, 5 is a backwash drainage tank, 5a is a float pump, 5b is an underwater wastewater pump , 6 is a sand filtration device, 7 is a metering tank, 8 is a quick stirrer, 9 is a slow stirrer, 10 is a pH adjuster supply device, 11 is a flocculant supply device, 12 is a coagulation sedimentation tank, and 12a is an air lift pump. , 13 is a measuring tank, 14 is a concentrated sludge tank, 14a is a suction pump, 15 is a sludge tank, 16 is a filter press, 17 is a dehydrator shooter, 18 is a roll-on container, 19 is a truck, and 20 is a control panel.

  As shown in FIG. 1, the wastewater treatment facility of the water purification plant of this embodiment is provided with a plurality of sedimentation basins 1 for storing raw water and precipitating sludge in the raw water, and the sludge is removed in each sedimentation basin 1. A filtration pond 2 for collecting and filtering the clear water, a drain pit 3 for controlling the discharge of backwash water from the filtration pond 2, and a sediment for collecting and temporarily storing sludge precipitated in each sedimentation basin 1 A pond drainage mud storage tank 4 is provided, a backwash drainage tank 5 for storing the backwash water of the filtration pond 2 drained in the drainage pit 3 and precipitating sludge in the backwash water is provided. An underwater sewage pump 5b for sending the precipitated sludge to the settling pond waste mud storage tank 4 is provided, and a sand filtration device 6 for further filtering and discharging the supernatant water of the backwash drainage tank 5 is provided.

  In addition, a measuring tank 7 for measuring and discharging a predetermined amount of mud from the sedimentation tank waste mud storage tank 4 is provided, and a quick stirrer 8 for rapidly stirring the sludge sent from the measuring tank 7 is provided. 8 is provided with a slow agitator 9 for slowly stirring the sludge agitated in 8 and a pH adjuster supply device 10 for supplying a pH adjuster to the rapid agitator 8. A flocculant supply device 11 for supplying a flocculant is provided, a coagulation sedimentation tank 12 for precipitating and separating the coagulated sludge is provided, a measuring tank 13 for measuring the precipitated coagulated sludge and feeding a predetermined amount is provided, and the mud is fed. A concentrated sludge tank 14 for concentrating the aggregated sludge is provided, and a suction pump 14a for sending the concentrated concentrated sludge is provided.

  Further, a sludge tank 15 for temporarily storing the concentrated sludge sent by the suction pump 14a is provided, a filter press 16 for dewatering the concentrated sludge in the sludge tank 15 is provided, and the dewatered dehydrated sludge is rolled on the truck 19. A dehydrator shooter 17 for discharging to the container 18 is provided, and a control panel 20 for controlling the valves of each part is provided.

  In this embodiment, first, raw water taken from rivers, dams, groundwater, etc. is stored in a plurality of sedimentation basins 1 to precipitate and separate sludge in the raw water, and the separated supernatant water is sent to the filtration basin 2 and settled. The settling sludge is sent to the settling pond waste mud storage tank 4. In the filtration pond 2, the supernatant water is filtered and supplied to the outside as clean water, and the backwash water obtained by backwashing the filter pond 2 is stored in the backwash drain 5. The supernatant water precipitated and separated in the backwash drain 5 is sent to the sand filter basin 6 by the float pump 5a, filtered and discharged to the water source, and the precipitated sediment sludge is stored in the sediment basin drainage tank by the submersible sewage pump 5b. 4 to send mud. In addition, the process of the backwash drainage tank 5 is shown in the chart of FIG.

  Here, since the backwash water was conventionally sent to the sedimentation basin sludge storage tank 4 as it is, it is necessary to make the sedimentation basin sludge storage tank 4 large-capacity, and a large amount of low-concentration sludge can be removed in a short time. In addition, a large-scale sludge treatment device is required, which requires equipment costs and treatment efficiency. However, in this embodiment, since the backwash water is once separated and separated in the backwash drain 5 and only the high-concentration sediment sludge is sent to the sediment basin sludge storage tank 4, the volume of the supernatant water to be discharged is the volume. The size of the sludge treatment device can be reduced because the sludge has a small amount and high concentration, and the backwash drainage tank 5 is less expensive than the membrane filtration device, and the cost is high. It becomes efficiency.

  Thereafter, the sludge in the settling pond waste mud storage tank 4 is weighed in the measuring tank 7 and discharged in a predetermined amount, and the pH adjusting agent supply device 10 and the flocculant supply device 11 add predetermined amounts of the pH adjusting agent and the flocculant. The agitation sludge is agitated in order by the rapid agitator 8 and the slow agitator 9, and the agglomerated sludge is sent to the agglomeration sedimentation basin 12.

  The fed sludge is separated and separated in the coagulation sedimentation tank 12, and the supernatant water is discharged to the water source, and the precipitated coagulated sludge is sent to the measuring tank 13 by the air lift pump 12a. The agglomerated sludge sent to the sludge is concentrated by discharging a predetermined amount to the concentrated sludge tank 14 in the measuring tank 13, and sent to the sludge tank 15 by the suction pump 14a. The sludge in the sludge tank 15 is dehydrated by a filter press, and the dehydrated sludge is accommodated in a roll-on container 18 by a dehydrator shooter 17 and conveyed to a predetermined place by a truck 19.

For reference, the facility cost and the amount of treated water in this example and the conventional example were compared. In this embodiment, 120 m ³ / day of sediment sludge from each sedimentation basin 1 is sent to the sediment basin sludge storage tank 4, and 66 m ³ / day of backwash water obtained by backwashing the filtration pond 2 is backwash drainage tank. 5 is sent to the water. 20m ³ / day of sediment sludge separated and separated in the backwash drain 5 is sent to the sedimentation basin sludge storage tank 4, and the sediment sludge in the sedimentation basin waste sludge storage tank 4 is treated 140m ³ / day and dehydrated cake. Is generated at 500 L / day. The volume of the backwash drain 5 is 90 m ³ , and the volume of the sedimentation basin mud storage tank 4 is 60 m ³ .

In the conventional example, 120 m ³ / day of sediment sludge from each sedimentation basin and 66 m ³ / day of backwash water obtained by backwashing the filtration pond are respectively sent to the sedimentation pond waste mud storage tank, and the same sedimentation pond waste mud storage tank Of 186 m ³ / day is processed to produce 500 L / day of dehydrated cake. The volume of the sedimentation tank waste mud storage tank is 150 m ³ .

As a result, the civil engineering work cost associated with the installation of the sedimentation basin mud storage tank 4 and the backwash drainage tank 5 of this example is approximately 30 million yen, and the civil engineering work cost associated with the installation of the sedimentation pond waste mud storage tank of the conventional example is approximately It was 40 million yen. In addition, the amount of sludge to be treated is 140 m ³ in this example, and 186 m ^{3 in} the conventional example, and this example reduces the amount of discharge due to the high concentration, thereby reducing the scale and capacity of the sludge treatment apparatus by about 20%. We were able to reduce it.

  The wastewater treatment method of the water purification plant of the present invention is mainly used for waterworks, but can also be applied to purification of lake water and river water.

It is explanatory drawing of the waste mud treatment equipment of the water purification plant of an Example. It is a chart which shows the process of the backwashing drainage tank of an Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Sedimentation basin 2 Filtration pond 3 Drainage pit 4 Sedimentation basin mud storage tank 4a Submersible sewage pump 5 Backwash drainage tank 5a Float pump 5b Submersible sewage pump 6 Sand filter 7 Measurement tank 8 Rapid stirrer 9 Slow agitator 10 pH Conditioner supply device 11 Coagulant supply device 12 Coagulation settling tank 12a Air lift pump 13 Metering tank 14 Concentrated sludge tank 14a Suction pump 15 Sludge tank 16 Filter press 17 Dehydrator shooter 18 Roll-on container 19 Truck 20 Control panel

Claims (4)

  A water purification plant that separates the raw water into a sedimentation basin, purifies the supernatant water through a filtration pond and purifies it, and temporarily stores the separated sludge in the sedimentation pond waste mud storage tank until it is sent to the sludge treatment unit. In the wastewater treatment method, the backwash water obtained by backwashing the filtration basin is separated by precipitation in a backwash drainage tank, and the separated high concentration sedimentation sludge is sent to the sedimentation pond wastewater storage tank. A wastewater treatment method at a water purification plant.   The wastewater treatment method for a water purification plant according to claim 1, wherein the sludge treatment device concentrates and agglomerates the sludge in the settling pond wastewater storage tank for dehydration.   The wastewater treatment method of a water purification plant according to claim 1 or 2, wherein the supernatant water of the backwash drainage tank is filtered and discharged.   A wastewater treatment method for a water purification plant, wherein the wastewater treatment method for a water purification plant according to any one of claims 1 to 3 is used for water supply.

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