JPH0139838B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] This invention does not require a complicated supernatant liquid discharge device, and the supernatant liquid can be discharged by simply allowing wastewater to flow into a treatment tank at a predetermined time. The purpose is to provide a batch-type wastewater treatment method that can be carried out.

[Conventional technology]

Conventionally, in batch type activated sludge treatment equipment,
Since the water level in the tank fluctuates, the supernatant liquid discharge device becomes complicated, and there are times when the water level is low, so the effective volume is small.

[Summary of the invention]

This invention was made in order to eliminate the above-mentioned drawbacks, and when discharging inflow wastewater into a single treatment tank that repeats each treatment process of aeration, precipitation, and discharge, new water is added to the treatment tank. By supplying sewage and forcibly raising the water level in the tank, the supernatant liquid after the precipitation step can be smoothly and efficiently discharged without the need for a complicated supernatant liquid discharge device, It is an object of the present invention to provide a batch-type sewage treatment method that can improve sewage treatment efficiency and effectively utilize the inside of the tank.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings.

As shown in FIG. 2, the treatment tank 1 shown in FIG. 1 performs wastewater treatment by repeating the steps of aeration, sedimentation, and inflow and discharge. This treatment tank 1 is provided with an overflow weir 2 at its upper part. On the other hand, an aeration device 3 for blowing air into wastewater in the aeration process and a sludge drawing section 4 are provided at the bottom.
The sludge extracted by the sludge extraction section 4 is disposed of separately.

The aeration device 3 is normally connected to an aeration blower (not shown) that is controlled on and off. It is preferable to use one that is difficult to clean. In addition, 6 is a buttful for short circuit prevention. Since the inflowing sewage is always brought into contact with and adsorbed by the precipitated activated sludge by this baffle 6, it is not discharged untreated together with the supernatant liquid.

The storage tank 5 temporarily stores wastewater to be treated, and a pump (sewage supply means) for supplying wastewater into the treatment tank 1 is provided in the storage tank 1.
7 is installed.

Next, the operation of the present invention will be explained.

The wastewater to be treated first flows into the storage tank 5,
It will be stored here. As shown in FIG. 2, when the treatment tank 1, in which each process is repeated, shifts to the inflow/discharge process, the pump 7 is driven, and the storage tank 5
The wastewater inside is supplied to the treatment tank 1. Due to the inflow of this wastewater, the water level in the treatment tank 1 rises from the aeration level (WL ₁ ), and the treated supernatant liquid is discharged overflow from the overflow weir 2. Then, when the inflow/discharge process is completed, the surplus sludge from the sludge extraction section 4 is pulled out of the system, or the tank liquid such as the extracted sludge is returned to the storage tank 5, thereby reducing the amount of water in the treatment tank 1. The water level is lowered to the aeration level (WL ₁ ) to prevent sludge from overflowing during the aeration process, and the process moves to the aeration process.

The purpose of lowering the water level in the tank in this way is to prevent sludge from overflowing during the aeration process, so the overflow weir 2 may be of an interlocking movable type as shown in FIG.

That is, in the overflow weir 2 of FIG. 3a, the overflow port 2a at the discharge position (during discharge) is rotated and held above the water surface during aeration. In addition, in FIG. 3b, the overflow weir 2 is raised during aeration, and the overflow weir is held in the direction of the water surface during the aeration process to prevent sludge from overflowing due to aeration. Moreover, the overflow of sludge during the aeration process is not restricted, and the supernatant liquid mixed with sludge at the time of discharge may be returned to a storage tank or the like.

As described above, in this invention, wastewater flows into the treatment tank 1 during the discharge process, the water level in the tank is raised, and the treated supernatant liquid is discharged overflow, so the supernatant liquid is discharged from a decanter or the like having a complicated structure. Effective treatment can be performed without using a discharge device. Moreover, since the water level in the tank can be kept almost constant, the capacity can be used effectively.

FIG. 4 shows an embodiment in which the processing tank 1 is composed of two tanks, tank A and tank B. Both tanks have the structure shown in FIG. 5, but the processing steps in tank A are shifted as shown in FIG. 6a, and in tank B as shown in FIG. 6b.

In this way, if the treatment tank 1 is made into two tanks and sewage is sequentially supplied, the sewage will be discharged from the storage tank almost continuously, and the capacity of the storage tank 5 can be reduced.

In addition, if two or more tanks are used, completely continuous supply of wastewater is also possible.

FIGS. 7 and 8 show another embodiment in which dirt on the side wall 1a above the aeration water level and inside the overflow weir 2 can be washed, and sewage is dividedly introduced into the lower part of the sludge zone 10.

In this embodiment, a plurality of nozzles 8 that inject liquid toward the inside of the side wall 1a and the overflow weir 2 are arranged above the aeration water level [WL ₁ can be lowered.

Furthermore, in this embodiment, although the baffle 6 shown in FIGS. 1 and 5 is not arranged, the sludge zone 1
A wastewater supply pipe 11 is arranged inside the tank 0, and the wastewater is divided into parts. Therefore, in addition to the above-mentioned effects, since contact with sewage and sludge can be carried out efficiently, it is difficult to cause short-circuit discharge, and furthermore, since sewage can quietly flow in, there is no risk of the settled sludge being rolled up and sludge being discharged.

Moreover, if the baffle 6 is provided, disturbances at the time of inflow can be further suppressed.

〔Effect of the invention〕

As described above, according to the present invention, in the batch activated sludge treatment cycle in which aeration, precipitation, and discharge steps are repeated, the sewage supply means is operated only during the discharge step to forcefully flow sewage into the treatment tank. ,
By raising the water level in the treatment tank due to the forced inflow of sewage, the supernatant liquid in the tank after the precipitation process can be smoothly discharged from the overflow weir, and therefore, in the discharge process, The supernatant liquid after the precipitation step can be efficiently discharged without requiring any complicated supernatant liquid discharge device.

Moreover, after the discharge process, the water level in the tank can be adjusted by stopping the operation of the sewage supply means, and by withdrawing excess sludge in the treatment tank to the outside of the system or returning tank liquid such as sludge to the storage tank. Lower the water level than the overflow weir, that is, lower the water level so that it will not be released from the overflow weir even if aerated. Since the aeration/sedimentation step is carried out in this state, the sludge in the tank will not be discharged overflow from the overflow weir, especially during the aeration step. In addition, in any of the above aeration and precipitation steps, the supernatant liquid is not discharged from the overflow weir into the overflow, so although the structure is extremely simple and costs can be reduced, the above batch type The activated sludge treatment cycle can be repeated smoothly and reliably, the sewage treatment efficiency can be improved, the capacity inside the tank can be effectively utilized, and it can be easily applied to existing treatment tanks, among other excellent effects.

Further, in the embodiment of the present invention, a buttful having an opening at the bottom is provided on the sewage inflow side of the treatment tank, so that the wastewater flowing into the treatment tank is partitioned by the buttful inside the tank. The precipitated activated sludge is oxidized and adsorbed in the formed sewage inlet, and then led to the lower opening of the baffle, where it also flows into the lower layer of the precipitated activated sludge and is purified by oxidation and adsorption. For this reason,
The above-mentioned inflowing sewage can effectively contact the sludge in the tank and will not be short-circuited and the sewage will flow in quietly, so the effect is that the settled sludge will not roll up and only the clear supernatant liquid can be discharged. be.

[Brief explanation of drawings]

Fig. 1 is a longitudinal cross-sectional view of one embodiment of the present invention;
The figure is a treatment process diagram of the treatment tank, Figure 3 is an explanatory diagram of the movement of the overflow weir, Figure 4 is a plan view of another embodiment, Figure 5 is a longitudinal cross-sectional view of the same, and Figure 6 is a diagram of the treatment tank. 7 is a plan view of another embodiment, FIG. 8 is a longitudinal sectional view thereof, and FIG. 9 is a sectional view taken along the line X--X of FIG. 8. 1...Treatment tank, 2...Overflow weir, 5...Storage tank, 7...Pump, 11...Sewage supply amount.

Claims (1)

[Claims] 1. A batch-type activated sludge treatment tank that treats sewage by repeating the aeration process, precipitation process, and discharge process of inflow sewage, and an overflow weir installed at the top of this treatment tank for discharging supernatant liquid. and a sewage supply means for intermittently supplying sewage into the treatment tank. New wastewater is supplied into the treatment tank, thereby forcibly raising the water level in the treatment tank, and the supernatant liquid generated in the treatment tank after the completion of the sedimentation process is overflowed. The above discharge process is carried out by overflowing the water out of the system through the weir,
The discharge process is terminated by stopping the operation of the sewage supply means, and then the water level in the treatment tank is raised to be lower than the upper end of the overflow weir by drawing out tank liquid such as sludge from the treatment tank. A sewage treatment method characterized by lowering the wastewater to a low position and moving to the aeration/sedimentation step in this state.