JPH0122835B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a batch activated sludge treatment method and apparatus that utilize a rotating disk for wastewater.

(Prior art) In the batch activated sludge method, each process such as aeration, sedimentation, discharge of treated water, and injection of waste water is carried out in one treatment tank, and the duration of each process and the length of one cycle are limited. By adjusting the time, it is possible to deal with fluctuations in the inflow volume and sewage load, and since there is only one treatment tank, there is no need to return sludge, making the equipment compact and reducing construction costs and land. One of its characteristics is that it requires less space. Furthermore, since the sludge is settled in a static state, clear treated water can be obtained, and operation management is easy, so it has recently been attracting attention as a treatment technology suitable for small-scale treatment plants.

However, the batch activated sludge method, like the standard activated sludge method, had the disadvantage of difficulty in controlling the bulking phenomenon, but in recent years, unlike the conventional continuous aeration method, wastewater It has been experimentally discovered that by stopping aeration when injecting sludge, it is possible to temporarily create an anaerobic state and suppress the bulking phenomenon. (Refer to Special Publication No. 55-24957).

(Problems to be Solved by the Invention) However, it is desired that this type of sewage treatment apparatus and method be more compact than existing ones, consume less energy, have good purification efficiency, and be easy to maintain.

(Means for Solving the Problems) In order to achieve the above-mentioned requirements, in the method of the present invention, sewage is poured into the treatment tank to a low water level where the rotating disk is immersed by about 40%, and the rotating disk is placed in this state. The first step is acclimatization operation at high speed, the second step is when the biofilm purification ability is stabilized, the jet aerator is operated with the rotating disk at high speed to perform nitrification operation, and the jet aerator is stopped. At the same time, there is a third step in which wastewater is poured to a high water level where the rotating disk is 100% immersed, and denitrification operation is performed in this state, and the jet aerator is restarted while the water level remains high to circulate wastewater and aerate the tank. a fourth step of performing an aeration operation that causes
The fifth step is to stop the jet aerator and operate the rotary disk at low speed to perform sedimentation, the sixth step is to extract the supernatant of the purified treated water, and a part of the settled sludge is pulled out from the sludge discharge port. The seventh step of sending the sludge to the sludge tank is repeated.

Furthermore, the apparatus of the present invention includes a rotary disk device provided in a recirculation type treatment tank, a jet aerator, and a sewage inflow device for this treatment tank;
A batch type activated sludge treatment apparatus using a rotating disk is constructed by providing a supernatant water discharge device, a sludge discharge device for discharging sludge settled in a treatment tank, and a sludge tank for storing the discharged sludge.

(Function) As described above, since the present invention has a rotating disk device and a jet aerator added to the recirculation type treatment tank, the rotating disk increases the contact area with wastewater, and The aeration effect can be enhanced by a jet aerator. Therefore, the apparatus of the present invention can reduce the installation area and improve processing efficiency.

In addition, the method of the present invention creates an aerobic state, an anaerobic state, or a static state by changing the degree of immersion and rotational speed of the rotating disk, thereby controlling the inflow of wastewater → denitrification operation → aeration operation → By creating a treatment cycle consisting of sedimentation → supernatant water discharge → nitrification operation, by adjusting the duration of each process, it is possible to achieve the optimal treatment method for treated wastewater, and also to By using the limited aeration method, the bulking phenomenon can be suppressed and the treatment efficiency can be improved.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

First, as an apparatus, as shown in the plan view of FIG. A disk device 2 is provided. 2a is its rotating disk, 2b is a motor, and 2c is a transmission device such as a chain.

Further, 3 is a jet aerator provided on the upstream side and the downstream side of the rotating disk device 2, 3a is a pressure water supply pipe thereof, and 3b is a nozzle. Fig. 3 shows the details of this process, which is performed by ejecting treated water or water from another water source through the pipe 3a from the nozzle 3b, and by the negative pressure generated at the ejecting part. The air is sucked in through a pipe 3c, and the air is injected into the processing tank 1 together with the jetted water. Alternatively, the jet aerator 3 may be configured to blow compressed air directly into the treatment tank 1, but in any case, the jet aerator 3 causes wastewater to circulate inside the treatment tank 1 and at the same time , which performs an aeration effect.

Further, 4 is a wastewater inflow device for the treatment tank 1 provided between the jet aerator 3 on the upstream side of the rotating disk device 2 and the rotating disk device 2, 4a is its pump, 4b is a wastewater inflow pipe, and 4c is a wastewater inflow device. It is an on-off valve. Further, 5 is a processing tank 1 provided between the jet aerator 3 on the downstream side of the rotating disk device 2 and the rotating disk device 2.
In the supernatant water discharge device, 5a is its discharge pipe, 5b
is an on-off valve. Furthermore, 6 is for discharging the sludge settled in the treatment tank 1 between the jet aerator 3 installed on the upstream side of the rotating disk device 2 and the jet aerator 3 installed on the downstream side to the outside of the treatment tank 1. 6a is the discharge pipe, and 6b is the on-off valve. Further, 7 is a sludge tank connected to the discharge pipe 6a and installed outside the treatment tank 1.

Next, the method of the present invention performed using the apparatus of the present invention configured as described above will be explained.

First, as the first step, a rotating disk 2 is placed inside the processing tank 1.
Sewage is poured to a low water level L where a is immersed by about 40%, and in this state, the rotating disk device 2 is operated at high speed to perform acclimatization operation in which biofilm is deposited on the disk surface.

Next, in the second step, when the biofilm purification ability is stabilized, nitrification operation is performed by operating the jet aerator 3 while keeping the rotating disk device 2 at high speed.
Next, as a third step, the jet aerator 3 is stopped, and the waste water is introduced by the waste water inflow device 4 to a high water level H where the rotating disk 2a is 100% immersed.
Denitrification operation is performed in this state. In the fourth step, the jet aerator 3 is restarted while the water level remains high, and an aeration operation is performed in which the wastewater is circulated and aerated within the treatment tank 1. After performing this aeration operation, as the fifth step,
The jet aerator 3 is stopped, and the rotary disk device 2 is operated at a low speed of 1/3 to 1/5 of the high speed operation to bring the inside of the treatment tank 1 into a gentle state with little circulation to perform the sedimentation action. Next, as a sixth step, the supernatant of the treated water purified as described above is extracted from the high water level H to the low water level L via the supernatant water discharge device 5. After that, as the seventh step, once a day
A part of the sludge that has settled for several times is extracted through a sludge discharge device 6 and sent to a sludge tank 7. The method of the present invention involves repeating the first to seventh steps described above.

The batch activated sludge treatment method using the rotating disk of the present invention consists of the treatment process as described above, namely, sewage inflow → denitrification operation → aeration operation → sedimentation → supernatant water discharge → sludge discharge (approximately once a day). ) → Since the cycle of nitrification operation is repeated, it is possible to suppress the bulking phenomenon and improve treatment efficiency by using a type of limited aeration method that is different from the continuous aeration method.

In the treatment process that is repeated in this way, the rotating disk 2a is operated in a 100% immersed state during the denitrification operation, so the surface of the disk becomes anaerobic.
The nitrite nitrogen and nitrate nitrogen that were nitrified in the previous process are reduced to nitrogen gas by the action of denitrifying bacteria, resulting in denitrification. Furthermore, in the subsequent aeration operation, the rotary disk 2a is operated at high speed with 100% immersion, so combined with the action of the jet aerator 3, the DO increases and the pre-processing is performed so that clean treated water can be obtained by re-aeration. The remaining BOD is removed by the process, and then the water is allowed to settle in a gentle state, allowing for effective wastewater purification.

Further, after the supernatant water discharge and sludge discharge process, the rotating disk 2a is operated at high speed in a state of approximately 40% immersion, and nitrification operation is performed while circulating and aerating, to ensure sufficient activity of nitrifying bacteria. Another feature of the method of the present invention is that the process prepares for the subsequent inflow of new wastewater and denitrification operation.

As described above, the present invention utilizes the rotating disk as an important part of the apparatus in the batch activated sludge process, thereby increasing the contact area with wastewater, improving purification efficiency, and making the apparatus more compact. aerobic, anaerobic or gentle conditions are created by varying the degree of immersion and rotational speed of the rotating disk device, especially during the treatment process;
It allows various processing processes to emerge. Furthermore, by adding a jet stream from a jet aerator to this, the aeration effect can be further enhanced and the treatment efficiency can be increased.

Moreover, by adjusting the duration of each process in the treatment cycle, it is possible to perform optimal treatment for various types of wastewater, and it is also possible to automate the treatment, so according to the present invention, maintenance management is possible. It is possible to obtain a batch type activated sludge treatment device that is easy and labor-saving.

(Effects of the Invention) As described above, the present invention has a rotating disk device and a jet aerator added to the circulation type treatment tank, so the rotating disk increases the contact area with wastewater. At the same time, the jet aerator can enhance the aeration effect. Therefore, compared to conventional devices of this type, the device of the present invention has excellent effects in that the installation area can be reduced and processing efficiency can be increased.

In addition, the method of the present invention creates an aerobic state, an anaerobic state, or a static state by changing the degree of immersion and rotational speed of the rotating disk, thereby controlling the inflow of wastewater → denitrification operation → aeration operation → By creating a treatment cycle consisting of sedimentation → supernatant water discharge → nitrification operation, by adjusting the duration of each process, it is possible to achieve the optimal treatment method for treated wastewater, and also to Since the bulking phenomenon can be suppressed by using the limited aeration method, the present invention has the excellent effect of significantly improving treatment efficiency.

[Brief explanation of drawings]

Fig. 1 is a plan view of a batch type activated sludge treatment equipment using a rotating disk according to the present invention, and Fig. 2 is its A-
A sectional view and FIG. 3 are partial sectional views showing an example of a jet aerator. 1... Treatment tank, 2... Rotating disk device, 3... Jet aerator, 4... Sewage inflow device, 5...
Supernatant water discharge device, 6...Sludge discharge device, 7...Sludge tank.

Claims (1)

[Claims] 1. A first step in which wastewater is poured into one treatment tank to a low water level at which the rotating disk is immersed by about 40%, and the rotating disk is acclimatized at high speed in this state; The second step is to operate the jet aerator while keeping the rotating disk at high speed to perform nitrification operation once the purification ability of the wastewater has stabilized, and the second step is to stop the jet aerator and increase the water level so that the rotating disk is 100% immersed in the wastewater. Fill it up to
The third step is to carry out denitrification operation in this state, the fourth step is to restart the jet aerator while the water level is still high and perform an aeration operation to generate wastewater circulation and aeration in the tank, and the fourth step is to stop the jet aerator. A fifth step in which the rotating disk is operated at low speed to perform sedimentation, a sixth step in which the supernatant of the purified treated water is extracted, and a portion of the settled sludge is pulled out from the sludge discharge port and sent to the sludge tank. A batch activated sludge treatment method using a rotating disk, characterized in that seven steps are repeated. 2 A rotating disk device is installed in one treatment tank of the circulation type, and a jet aerator is installed, and a sewage inflow device and a supernatant water discharge device are installed for this treatment tank to discharge the sludge that has settled in the treatment tank. A batch-type activated sludge treatment device that utilizes a rotating disk that includes a sludge discharge device and a sludge tank that stores the discharged sludge.