JPH02265699A - Batch activated sludge treatment method and device for sewage - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method and apparatus for treating sewage, and particularly to a batch activated sludge treatment method for sewage in which sewage is treated by sequentially repeating aeration, precipitation, and wastewater treatment. and its apparatus.

[Conventional technology]

Conventionally, when sewage discharged from factories, etc. is treated with activated sludge in a batch manner, the sewage is aerated in the same tank, then subjected to sedimentation treatment to separate settled sludge and supernatant water, and the supernatant water is sent to a drainage system. Drained. In this case, when new sewage flows into the sedimentation process or drainage process, the supernatant water becomes turbulent, and the separated supernatant water and sludge mix again. There is a problem of mixing. Therefore, since the wastewater needs to flow in during the aeration process, the time for the wastewater to flow is limited.

Therefore, in order to solve this problem, Tokuko Sho: 18-3823
Publication No. 3 discloses a wastewater treatment method that allows wastewater to be discharged even during the precipitation process and the drainage process. This processing method is
A partition wall is installed inside the treatment tank to form a new inflow zone,
It is characterized by using a sewage treatment device in which an opening is provided at the lower end of the partition wall to communicate the inflow zone and the treatment tank.

According to this sewage treatment equipment, sewage flows into the inflow zone, and the sewage in the inflow zone flows into the treatment tank through the opening in the partition wall, so even during the sedimentation process and the drainage process, the sewage in the treatment tank flows into the inflow zone. No turbulence occurs. Therefore, the inflowing sewage does not short-circuit with the sewage in the treatment tank, so that the sewage can continuously flow into the treatment tank during any of the aeration, precipitation, and drainage treatments.

[Problem to be solved by the invention]

However, in this method, the excess sludge extracted from the treatment tank has a low concentration, and unless it is concentrated again, it will be difficult to perform dewatering treatment in the subsequent process. For this reason, a glue tank is installed outside;
Excess sludge is reconcentrated and then dehydrated.

In addition, the supernatant water from the reconcentration is returned to the raw wastewater side.

Therefore, in order to obtain highly concentrated thickened sludge, equipment such as tank A, a drawing pump, and piping must be installed externally, which increases the size of the equipment.Also, the sedimentation process in the thickening tank is carried out efficiently, and the total amount of sludge drawn out is In order to turn sludge into thickened sludge, it is necessary to maintain a large amount of surplus extraction at the minimum necessary level, which poses a problem in that the operation is difficult.

The present invention was made in view of these circumstances, and uses simple a-condensation treatment equipment and simple equipment operation to treat high-concentration awJ.
An object of the present invention is to provide a batch activated sludge treatment method for sewage that can yield sludge, and an apparatus therefor.

[Means for Solving the Problems] In order to achieve the above-mentioned object, the present invention adds activated sludge from a thickening tank to sewage that continuously flows into a pre-aeration tank to form mixed sewage, and aerates the mixed sewage. After that, the Sawaai sewage is allowed to flow into the treatment tank in a state that prevents turbulence, and the Sawaai sewage is aerated in the treatment tank, and then subjected to sedimentation treatment to be separated into sludge and supernatant water, and the separated supernatant water is released from the treatment tank. The water was drained, and the treatment steps were repeated in the order of steps, and the mixed sewage during the aeration step, or the sludge separated during the precipitation step or after the precipitation, was flowed from the treatment tank into the thickening tank as activated sludge, and then flowing into the thickening tank. The system is characterized in that the activated sludge is precipitated and discharged from the thickening tank, and the activated sludge that does not settle is allowed to overflow from the thickening tank and is charged into the pre-aeration tank.

Furthermore, in order to achieve the above object, the present invention provides a batch type activated sludge treatment apparatus for sewage in which sewage in a treatment tank is subjected to aeration and precipitation treatment to separate it into sludge and supernatant water, and the supernatant water is treated as waste water. There is a thickening tank into which mixed sewage during the aeration process or separated sludge from the sedimentation process or after sedimentation flows from inside the treatment tank, activated sludge overflowing from the thickening tank, and newly released sewage flow into the thickening tank. A pre-aeration tank, mixed sewage during the aeration process, or separated sludge from the sedimentation process or after precipitation flows from the treatment tank into the thickening tank, the precipitated sludge is discharged into the thickening tank, and from the thickening tank it flows into the pre-aeration tank. A treatment device that mixes the overflow activated sludge and sewage that has newly flowed into the pre-aeration tank to form mixed sewage, aerates the mixed sewage, and causes the mixed sewage to flow from the pre-aeration tank into the treatment tank in a state of preventing turbulence; It is characterized by having the following.

[Effect]

According to the invention, the waste water is stored in a pre-aeration tank (1
6), it mixes with the activated sludge that has flowed in from the thickening tank (14) to become mixed sewage.The mixed sewage is aerated and flows into the inflow pipe (3).
2) and the turbulence prevention plate (30) into the treatment tank (12) without causing turbulence, and is separated into precipitated sludge and supernatant water through aeration and precipitation treatment. Clear water is drained by a drainage device (36).

While repeating the above steps sequentially, the mixed sewage during the aeration process or the sludge separated during the precipitation process or after the precipitation is flowed as activated sludge from the treatment tank (12) to the thickening tank (14) by the transfer pump (26), The sludge settled in the thickening tank (14) is discharged through the discharge pipe (44). The activated sludge that does not precipitate flows from the thickening tank (14) to the pre-aeration tank (16) and mixes with the sewage that has newly flowed into the aeration tank (16) to form mixed sewage. The mixed wastewater is aerated and flows into the treatment tank (12) through the inflow pipe (32) and the turbulence prevention plate (30).

Therefore, even during precipitation or discharge treatment other than aeration treatment, wastewater is passed through the treatment tank (16) through the pre-aeration tank (16).
2) It can flow into the interior.

Also, processing f! ! Since there is no need to settle all of the sludge that has flowed into the thickening tank (14) from (12), there is no need to maintain the minimum necessary amount of sludge to be drawn out, and it is easy to operate from the thickening line type (14) to the high concentration sludge. By pulling out the thickened sludge,
The sludge concentration in the treatment tank (12) can be maintained at a desired value.

Furthermore, since the concentration treatment equipment can be integrated with the treatment tank (12), the equipment can be made more compact.

〔Example〕

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the batch activated sludge treatment method and apparatus for wastewater according to the present invention will be described in detail below with reference to the accompanying drawings.

The sewage treatment equipment 10 shown in FIG. 1 mainly includes treatment h12,
It consists of a tvi 4 and a pre-aeration tank 16.

The processing tank 12 mainly includes a bottom surface 12A, a wall B17, and a wall portion 18.
and a stirrer 20.20 on the bottom surface 12A.
is included. The stirrer 20.20 is connected to the blower 24 via the supply pipe 22. Also, this bottom surface 12
A is provided with a transfer pump 26, and this transfer pump 26
A transfer pipe 28 is connected to. Discharge of transfer pipe 28-
28A is provided above the concentration tank 14, which will be described later.

Further, a turbulence prevention plate 30 is provided on the side wall 17 of the processing tank 12, and a lower end portion of an inflow pipe 32 is fixed to the turbulence prevention plate 30. The upper end of the inflow pipe 32 opens through the wall surface 17 to a set water level A of a pre-aeration tank 16, which will be described later. Therefore, the bottom of the treatment tank 12 is communicated via the inlet pipe 32 to the pre-aeration tank 16 at the set water level. Furthermore, a drain pipe 34 that opens to the outside of the processing tank 12 is provided on the wall surface 18 of the processing tank 12 . The drain pipe 34 is provided with an outlet 36 for discharging supernatant water. The discharge port 36 descends as the water level B decreases during the discharge process.

The concentration tank 14 is mainly formed of a wall 38 and a wall 40, the height of the wall 40 is lower than the height of the wall 38, and
The wall portion 40 is formed higher than the set water level of the pre-aeration tank 16.

Therefore, when the concentration tank 14 is supplied with wastewater and filled,
Sewage overflows from the upper end of the wall portion 40 and flows into a pre-aeration tank to be described later. A baffle plate 42 is provided in the upper part of the concentration tank 14 along the wall 38 to the left. Further, a mud drainage pipe 4 is provided at the lower end of the wall portion 38.
4, the sludge settled in the thickening tank 14 is discharged to the outside of the thickening tank 14 via the sludge drain pipe 44.

The pre-aeration tank 16 is mainly formed with a wall portion 40 and a wall portion 17, and an air diffuser 46 is provided at the bottom thereof. The air diffuser 46 is connected to the blower 24 via the supply pipe 22. A discharge port 48A of a sewage discharge pipe 48 is provided above the pre-aeration tank 16.

The operation of the batch-type activated sludge treatment method for sewage and the apparatus configured as described above according to the present invention will be explained.

Sewage discharged from factories and the like flows into the pre-aeration tank 16 through the sewage discharge pipe 48 and the discharge port 48A. The sewage that has flowed into the pre-aeration tank 16 is
It mixes with the activated sludge overflowing from the thickening tank 14 to become mixed sewage, which is aerated with air bubbles released from the air diffuser 46 via the blower 24 and supply pipe 22.

- When the aerated mixed wastewater exceeds the set water level A, it flows into the bottom of the treatment tank 12 via the inflow pipe 32 and the turbulence prevention plate 30. The mixed sewage that has flowed into the treatment tank 12 is mixed with the activated sludge in the treatment tank 12 by an agitator 20, 20, and is aerated to become activated sludge, which is then separated into sludge and supernatant water by a subsequent sedimentation process.

The separated supernatant water is drained to the outside of the treatment tank 12 through a descending drain port 36 and a drain pipe 34.

While repeating the above steps sequentially, the mixed sewage during the aeration process or the separated sludge during the precipitation process or after the precipitation is sucked up from the treatment tank 12 by the transfer pump 26, and the transfer pipe 2
8 and is transferred to a thickening tank 14 as activated sludge. In this case, the activated sludge is distributed between the wall portion 38 and the barafour plate 42.
Therefore, the released activated sludge is temporarily stored in the thickening tank 14 without overflowing into the pre-aeration tank 16. Therefore, sludge is precipitated in the poor grade 14, and the precipitated sludge passes through the sludge pipe 44 to the thickening tank 14.
is discharged from. In this way, the sludge that settles in the thickening tank 14 has a higher density than the precipitated sludge in the treatment tank 12 because the sludge in the treatment tank 12 is reprecipitated. Further, since the thickening tank 14 is provided with the sludge drain pipe 44, the settled sludge can be smoothly drained.

Furthermore, when the activated sludge that does not precipitate fills the thickening tank 14, this activated sludge overflows the wall portion 40 and flows into the pre-aeration tank 16. In this case, aw
Since the scum generated in the i-tank 14 flows into the pre-aeration tank together with the waste water, the scum does not stay in the concentration tank I4. The activated sludge that has flowed into the pre-air lane sump tank 16 is aerated with the sewage that has flowed in from the discharge port 48A of the sewage discharge pipe 48 in the same way as described above, and is treated by the aeration device 46 to eliminate sewage that tends to settle due to the initial adsorption action. It is possible to prevent spoilage by supplying oxygen.

Therefore, short circuit with the supernatant water in the treatment tank can be prevented. Furthermore, since the pre-aeration tank 16 is connected to the processing tank 12 via the inflow pipe 32 and the turbulence prevention plate 30, the pre-aeration tank 16 communicates with the processing tank 12
Even when the activated sludge flows into the treatment tank 12, turbulence does not occur in the activated sludge in the treatment tank 12. Thereafter, each process is repeated in the order of the above treatment steps to treat the wastewater.

〔Effect of the invention〕

As explained above, according to the batch-type activated sludge treatment method and apparatus for sewage according to the present invention, mixed sewage that has been aerated in advance in the pre-aeration tank can flow into the treatment tank without causing turbulence. The sewage can be discharged into the treatment tank even during aeration, sedimentation, or discharge treatment without reducing the sewage treatment capacity.

In addition, the new sewage that has flowed into the pre-aeration tank mixes with the activated sludge that has flowed from the thickened tank to become mixed sewage, and the mixed sewage is aerated and flows into the treatment tank.
The a-shrinkage sludge easily settles at the bottom of the treatment tank, and the thickened sludge that has settled at the bottom of the treatment tank in the thickening tank is reprecipitated, so highly concentrated thickened sludge can be discharged from the thickening tank.

Furthermore, since the activated sludge flows from the thickening tank into the pre-aeration tank, there is no need to precipitate the entire amount of sludge that has flowed into the thickening tank. Therefore, it is possible to improve the aggregation properties of excess sludge using compact equipment that is easy to replicate.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a batch-type activated sludge treatment apparatus for wastewater according to the present invention. IO...sewage treatment equipment, 12 river treatment tank, 14.
... amW, 16... pre-aeration tank, 26... transfer pump, 3o... turbulence prevention plate,
32... Inflow pipe, 42... Puffful plate,
44...Sludge drainage pipe, 48...Sewage discharge pipe, A
, B... Set water level.

Claims (3)

[Claims] (1) Activated sludge is added from the thickening tank to the sewage that continuously flows into the pre-aeration tank to form mixed sewage, and after the mixed sewage is aerated, it is continuously flowed into the treatment tank in a state that prevents turbulence. After the mixed sewage is aerated in the treatment tank, it is separated into sludge and supernatant water by sedimentation treatment, the separated supernatant water is drained from the treatment tank, and the above treatment steps are repeated in the order of the steps, and the water in the treatment tank is The mixed sewage during the aeration process, or the sludge separated during the precipitation process or after the precipitation, flows from the treatment tank into the thickening tank as activated sludge, and the activated sludge that has flowed into the thickening tank is precipitated and discharged from the thickening tank, A batch activated sludge treatment method for sewage characterized by overflowing unsettled activated sludge from a thickening tank and charging it into a pre-aeration tank. (2) In a sewage batch activated sludge treatment equipment that aerates and settles sewage in a treatment tank to separate it into sludge and supernatant water, and then treats the supernatant water as wastewater, mixed sewage during the aeration process, or A thickening tank into which sludge separated during the sedimentation process or after settling flows into the treatment tank; a pre-aeration tank into which activated sludge overflowing from the thickening tank and newly released sewage flow; and a mixing tank during the aeration process. Sewage or sludge separated from the sedimentation process or after settling flows into the thickening tank from the treatment tank, the settled sludge is discharged into the thickening tank, activated sludge overflows from the thickening tank into the pre-aeration tank, and activated sludge flows into the pre-aeration tank. A treatment device for mixing newly inflowing sewage to form mixed sewage, aerating the mixed sewage, and causing the mixed sewage to flow from a pre-aeration tank into a treatment tank in a state of preventing turbulence. type activated sludge treatment equipment. (3) The treatment device includes a transfer pump installed in the treatment tank to transfer the mixed sewage during the aeration process or the separated sludge after the sedimentation process or sedimentation to the thickening tank as activated sludge; When activated sludge transferred from the tank flows into the thickening tank,
In order to prevent overflow due to short circuit with the pre-aeration tank, a baffle plate installed in the thickening tank, a sludge pipe installed in the thickening tank to discharge the sludge settled in the thickening tank, and a thickening tank and pre-aeration tank are installed. Partition, a partition wall formed lower than other walls of the thickening tank and pre-aeration tank, an aeration device installed in the pre-aeration tank for aeration processing, and a partition wall set lower than the partition wall of the pre-aeration tank. It is installed at the inflow pipe that opens at a set water level and communicates the pre-aeration tank and the treatment tank, and at the drain port of the inflow pipe, and prevents the turbulent flow of sewage in the treatment tank when sewage flows in from the drain port. The batch activated sludge treatment apparatus for wastewater according to claim 2, further comprising: a turbulence prevention plate for preventing turbulence.