JPH022479Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a batch type activated sludge treatment apparatus that treats wastewater by alternately repeating an aeration process and a precipitation process in a single reaction tank.

In conventional batch-type activated sludge treatment equipment, treated water is discharged by precipitating sludge in a reaction tank and separating the supernatant liquid into an upper layer using a decanter. Sludge extraction is also carried out at a time when the sludge is settling.
Pulling out the precipitated sludge is advantageous in that highly concentrated sludge can be extracted, but it has the disadvantage that it is difficult to control the amount of sludge that is drawn out, and the amount of sludge present in the reaction tank is likely to be too large or too small. If the amount of sludge in the reaction tank is too small, the quality of the treated water will deteriorate because biological treatment is not carried out sufficiently, and if it is too large, the sludge will carry over when the supernatant liquid is discharged from the decanter. This may cause inconveniences such as
Control of the amount of sludge drawn is extremely important.

The purpose of this invention is to provide a batch type activated sludge treatment apparatus that can treat sewage under stable treatment conditions by always maintaining the amount of sludge in the reaction tank within a predetermined preferred range.

Next, an embodiment of this invention will be described with reference to the drawings. In the figure, an aeration pipe 2 for blowing air into the wastewater in an aeration process is disposed at the bottom of a reaction tank 1 capable of containing wastewater. Further, the vertically arranged baffle 3 is for preventing newly inflowing sewage from being immediately discharged.

The decanter 4 for discharging the supernatant liquid includes a discharge pipe 6 rotatably connected to a shaft pipe 5 about a horizontal axis, and an overflow pipe 7 attached to the free end of the discharge pipe 6. and floats 8, which also serve as scum baffles, located on both sides of this overflow pipe 7. The overflow pipe 7 is provided with an overflow port, and when the overflow pipe 7 is floating on the water surface,
The liquid in the reaction tank 1 enters the overflow pipe 7 from this overflow port, and is then discharged to the outside via the discharge pipe 6 and the shaft pipe 5. Further, in a state where the overflow pipe 7 is supported at a position higher than the water surface, the liquid in the reaction tank 1 is not discharged.

Further, a drawing pipe 9 for drawing sludge out of the reaction tank 1 is connected to a centrifugal superconcentrator 10, which is a type of centrifugal thickener. This centrifugal superconcentrator 10 is of a type in which a cloth is spread on the inner surface of a cone-shaped rotating drum, and the liquid to be concentrated is supplied onto the cloth while rotating the rotating drum at high speed. The thickened sludge returned to the inside of the cloth and released from the cloth by centrifugal force is taken out to the outside.
Further, in order to control the operation of the centrifugal superconcentrator 10, an MLSS meter 11 having a detection end 11a disposed at an appropriate position within the reaction tank 1 is provided. this
The MLSS meter 11 measures the MLSS of the liquid in the reaction tank 1 during the aeration process, and only when the measured value is higher than a preset value, the drawn pipe 9
After the liquid in the reaction tank 1 is drawn out through the centrifugal thickener 10, the thickened sludge is taken out to the outside, thereby reducing the MLSS of the liquid in the reaction tank 1. The drawing of this thickened sludge may be carried out only for a certain period of time after it is detected that the measured value of MLSS is equal to or higher than a set value, or the MLSS concentration may be measured even during drawing, and this measured value may be a predetermined lower limit. It may continue until the value is reached.

The MLSS meter 11 can also be used as an indicator to prevent sludge from carrying over when the supernatant liquid is discharged from the decanter 4. In this case, the detection end 11a of the MLSS meter 11
is installed at a position where it can detect the sludge surface at the highest level within the range where carry over does not occur during discharge, and MLSS measurements are also performed during discharge. If the sludge surface is lower than the detection end 11a, the measured value of MLSS is low, which indicates that there is no risk of carry over. In addition, if the sludge surface is higher than the position of the detection end 11a, take appropriate measures such as stopping the discharge and increasing the settling time or increasing the aeration air volume to shorten the aeration time. Can be done.

As described above, according to this invention, there is an MLSS meter that measures MLSS in a batch type single aeration tank and outputs only when the measured value exceeds a set value, and
The MLSS in the aeration tank can be controlled simply by combining it with a centrifugal concentrator operated by the output signal of the MLSS meter, and no other control elements are required.
The configuration is simple, significantly reducing costs, and maintenance is easy.Moreover, the centrifugal concentrator draws out the liquid in the reaction tank and converts it into concentrated sludge and filtrate when activated by the output signal of the MLSS meter. The concentrated sludge is separated and the concentrated sludge is discharged, while only the filtrate is returned to the reaction tank. By returning the filtrate, the MLSS that is becoming excessive in the reaction tank is diluted to the above set value, and the reaction begins. inside the tank
The MLSS can be maintained in a stable state at all times, allowing stable activated sludge treatment to be performed, and has the effect of preventing inconveniences such as sludge carry-over within a single reaction tank.

[Brief explanation of the drawing]

The figure is a schematic longitudinal sectional view showing a batch type activated sludge treatment apparatus according to an embodiment of the invention. 1... Reaction tank, 2... Diffusion pipe, 3... Buzzful, 4... Decanter, 9... Drawn pipe, 10...
...Centrifugal superconcentrator, 11...MLSS meter, 11a
...Detection end.

Claims (1)

[Scope of utility model registration request] a single reaction tank that receives inflow sewage and repeats an aeration process, a precipitation process, and a discharge process in that process order; an aeration pipe for blowing air into the liquid in the reaction tank during the aeration process; A decanter that is installed in the reaction tank and discharges the supernatant liquid in the discharge process, a centrifugal concentrator that takes in the atomized mixed liquid in the reaction tank and separates it into a filtrate and thickened sludge, and The concentration of suspended solids in the atomized mixed liquid in the reaction tank is immersed and fixed in the liquid, and only when the measured value exceeds a set value, a start signal is output to the centrifugal concentrator. and an MLSS meter that operates the centrifugal thickener, and when the centrifugal thickener is operated by an input signal from the MLSS meter, the thickened sludge separated by the centrifugal thickener is discharged to the outside, and the filtrate is returned to the reaction tank. Batch-type activated sludge treatment equipment featuring: