JPS5930158B2 - How to treat sewage - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a method for treating wastewater with activated sludge.

Activated sludge treatment methods are becoming widespread as a treatment method for wastewater such as factory wastewater, domestic wastewater, sewage, and human waste.

Batch processing is one of the activated sludge processing methods. Batch processing does not require a return means, and the aeration tank and sedimentation tank are all in one tank (furthermore, the sedimentation process can be carried out in a completely still state). It has many advantages such as

However, in conventional batch processing, wastewater generally flows in only during the aeration process, and when dealing with wastewater whose inflow time is not limited, the inflow water from one discharge cycle to the next discharge cycle is processed. It is necessary to store the water, and in particular, this capacity is determined according to the maximum inflow, so a large-capacity storage tank has become an essential requirement.

For this reason, batch processing is not used for such wastewater treatment, and is only used to a limited extent when specific conditions are met for the inflow of sewage, such as factory wastewater where sewage is generated only during the day.

In addition, a treatment method has been proposed in which the inflow of sewage is made to flow continuously without being restricted according to the treatment cycle, and the cycle of aeration, sedimentation, and discharge is repeated in the tank.With this method, there is no need for a settling chamber or return of sludge. Continuously flowing general wastewater can be efficiently treated while retaining the effects of batch processing.

In other words, this method has the advantage that there is almost no need to provide a wastewater storage tank (it can be treated in one tank).

However, even with this method, since the tank interior stores inflow water from one discharge cycle to the next discharge cycle, a surplus volume is required for this purpose, and this surplus volume also needs to be determined according to the maximum inflow volume. There was a drawback that the volume of the tank interior had to be increased when there were large fluctuations in the inflow amount.

This invention eliminates the above problems by repeatedly controlling the continuous process of aeration, sedimentation, and supernatant discharge of wastewater in a tank body into which wastewater flows, and also by adjusting the cycle time of this process to match the inflow amount. The purpose of the present invention is to provide a sewage treatment method that can be modified to reduce tank capacity.

Embodiments of the present invention will be described below based on the drawings.

FIG. 1 shows a sectional view of a sewage treatment device used in the sewage treatment method of the present invention, and FIG. 3 is an explanatory diagram of a control device that controls the sewage treatment device of FIG. 1.

A sewage inlet 2 is provided for continuous flow of sewage into one end 1a of a rectangular tank body 1 made of reinforced concrete or other suitable material, and a partition is provided adjacent to this end 1a to prevent short circuits. Wall 3 has a lower end of about 30
It is arranged to form an opening 3a with a height of about 07W7M.

The partition wall 3 and one end 1a constitute an inflow zone 4, and the partition wall 3 and the other end 1b of the tank body 1 constitute an air chamber 5.

In order to discharge supernatant liquid from the surface of the sewage contained in the tank body 1, a decanter 6 is disposed adjacent to the other end 1b on the opposite side of the sewage inlet 20.

This decanter 6 can take any suitable shape, but in this example, flow pipes 6b serving as scum baffles are fixed on both sides of the discharge vibro a, and are connected to a shaft pipe 7 by a bent pipe 6C. Penetrates the tank wall and is suitable for a drainage ditch.

The decanter 6 is supported by a shaft pipe 7, and its height can be moved up and down by rotating the shaft pipe with a drive device 8.

Further, a large number of air supply devices 9 are arranged at the bottom of the tank body 1, so that air can be fed under pressure from the outside in order to carry out aeration treatment for a predetermined period of time.

In addition, the inside of this tank body 1 includes an aeration process in which air is diffused and diffused over a predetermined period of time into the wastewater that has continuously flowed in, a precipitation treatment process in which air is precipitated over a predetermined period of time, and a supernatant liquid is discharged over a predetermined period of time. It is controlled to repeat a series of cycles of the clear discharge treatment process.

For this purpose, a control device, for example, a control panel 10, is disposed outside, and this control device controls the time required for each step in accordance with the inflow amount measured by a flow meter.

For example, as shown in the 2-port cycle pattern diagram in Figure 2, it takes 6 hours for one cycle in which the aeration treatment is set for 4.5 hours, the sedimentation treatment is set for 1 hour, and the supernatant discharge treatment is set for 0.5 hours6. It has two cycle patterns: a 3-hour cycle, in which the aeration treatment is set to 1.5 hours, the sedimentation treatment is set to 1 hour, and the supernatant discharge treatment is set to 0.5 hours. It is designed to be selected appropriately.

If the normal cycle is 6 hours, then the upper part of the tank body 1 has an extra volume V for the inflow amount for 6 hours, but if this is a 3 hour cycle, then the above V is the extra volume for the inflow water for 3 hours. Because of the extra capacity, processing is possible even if the inflow volume is doubled.

Note that the precipitation time and discharge time should be kept approximately constant because the minimum time is determined physically.

Furthermore, if necessary, the aeration intensity of the aeration treatment may be changed as the cycle is changed, but even if this is constant, it will not be a problem as long as the total amount of organic matter removed per day does not change significantly.

However, if all 6-hour cycles are used, the distraction period will be 18 hours per day, and if all 3-hour cycles are used, the distraction period will be 12 hours per day.
Therefore, it is desirable to plan changes to the cycle pattern according to the inflow pattern, etc.

Note that the height of the lower end opening 3a of the partition wall 3 in the tank body 1 is set to 30
The reason why it is set to 0 mm is that the degree of mixing of wastewater with the inflow zone 4 during agitation in the aeration chamber 5 is appropriate.

In this way, the sludge is placed in a state where the organic matter load is very high in the inflow zone 4, so that the settling property is improved and the treatment effect is enhanced.

As described above, according to the sewage treatment method of the present invention, the time required for one cycle of aeration, sedimentation, and supernatant discharge of sewage can be changed according to the inflow amount, and when the inflow amount is large, one cycle By shortening the time for sewage and lengthening the time for one cycle when the amount of inflow is small, the volume of the tank for storing sewage can be reduced even if the amount of sewage flowing in fluctuates, and sufficient treatment can be achieved.

Furthermore, there is no need for extra equipment such as a settling tank or return means.

In addition, in the above example, only the sewage treatment method in which the inflow is continuously inflowed without being restricted according to the treatment cycle, but even in the normal batch treatment method in which the inflow is restricted, the volume for storing the sewage can be reduced. A similar effect can be obtained.

[Brief explanation of drawings]

Figure 1 is a sectional view of a sewage treatment equipment used in the method of this invention, Figure 2 A is a cycle pattern diagram showing an embodiment of this invention, and Figure 3 is an explanatory diagram of the control system of the treatment equipment of Figure 1. It is. 1... Tank body, 1a... One end, 1b...
...Other end, 2...Sewage inlet, 3...
...Partition wall, 4...Inflow zone, 5...
・Air chamber, 6...Decanter, 10...
·Control device.

Claims (1)

[Claims] 1. An aeration step for aerating the sewage contained in the tank body, a precipitation step for precipitating the sewage contained in the tank body, and a discharge step for discharging the supernatant liquid obtained in this precipitation step. In a sewage treatment method using a batch activated sludge method in which sewage is treated by repeating these steps, the time of one cycle from one of the discharge steps to the next discharge step is determined according to the amount of inflow of sewage. A method for treating sewage characterized by changing the length to be short when the inflow is large and to long when the inflow is small.