JPH04108597A - Adjustment of flow amount in sewage septic tank - Google Patents

Abstract

PURPOSE:To control the speed of a rise in the water level of untreated sewage in a succeeding settling tank so as to prevent the overflow thereof by a method wherein, in a septic tank, the transfer of the sewage is controlled by an intermittent operation of an air lift tank so as to be in a predetermined average amt. CONSTITUTION:A septic tank 1 consists of a treating tank 1A. wherein sewage is held stationary to be settled and separated or treated by anaerobic microorganisms, a fluidized bed tank 1B for treating the sewage with aerobic microorganisms or contact aeration tank 1C, a settling tank 1D for settling sludge in suspension and a disinfecting tank 1E for disinfecting the liq. to be discharged. When the water level of the treating tank 1A reaches the highest water level HWL and the amt. of the sewage received is reduced, a control device 3 starts the force feeding thereof to the next treating tank. At this time, since the treating tank 1A has the highest water level HWL, the amt. of the liq. can be transferred in a large amt. by operating an air lift pump 2 at one time for a short period of time and, as the water level goes down, the driving time of the air lift pump 2 becomes longer and, for this reason, the amt. of the sewage transferred per unit time can be made nearly constant after all, thereby preventing the overflow or short pass of the sewage due to an abrupt rise in the water level of the next treating tank.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] This invention relates to a sewage septic tank, and relates to an improvement of a sewage septic tank.

[Conventional technology]

Conventionally, a small combined septic tank is equipped with a sedimentation separation tank No. 1.2 or an anaerobic filter bed tank box No. 1.2, a fluidized bed tank, a contact aeration tank, a sedimentation tank, a disinfection tank, etc., and sewage is sequentially advected to these tanks. Sewage septic tanks are known that purify wastewater.

Normally, in this type of sewage septic tank, the sewage generation time is uneven, so it is necessary to lower the water level in each treatment tank in advance to coincide with the peak inflow.
2 room or anaerobic filter bed box Publication No. 58-39836).

[Problems with conventional technology]

However, when advection is performed using an air lift pump or the like, there is a problem in that although the amount of air passage to the air lift pump is constant, the amount of advection to the downstream treatment tank varies considerably depending on the water level in the upstream treatment tank. For example, as shown in Figure 3, when the air supply rate is constant, 10β/min at full water level decreases rapidly with attenuation, and at the lowest water level Iff/min.
minute, and the effectiveness as a flow rate adjustment decreases.

Therefore, during times when a large amount of sewage is generated, the amount of transferred water increases as the water level in the first stage treatment tank rises, and as a result of the rapid rise in the water level in the second stage treatment tank, untreated water is discharged and flows into the second stage treatment tank. When there is a bed tank, there is a problem that the fluidized bed overflows and the water quality standards of the discharged water cannot be maintained sufficiently.

[Problem to be solved by the invention]

In view of the above-mentioned problems, the present invention has been made with the object of providing a sewage septic tank that can maintain a constant transfer amount of treated sewage regardless of the water level of the pre-treatment tank and can perform stable sewage purification.

[Technology that has led to solving the problem] That is, the sewage septic tank of the present invention has two types: a tank in which wastewater is left to stand for sedimentation separation or treatment using anaerobic microorganisms, and a fluidized bed tank or a tank in which treatment is performed using aerobic microorganisms. It is equipped with a contact aeration treatment tank, a settling tank for settling the final suspended sludge, and a disinfection tank for disinfecting the discharged liquid, and is transported from the tank where the sedimentation separation or treatment using anaerobic microorganisms is performed to the downstream treatment tank by an air lift pump. In a sewage septic tank that purifies sewage while adjusting the flow rate by forced advection of primary treated water, the air lift pump is controlled to operate intermittently by a control device, and the interval of the intermittent operation is determined by the water level in the pre-treatment tank. The spacing is coarse at the upper limit water level, and as the water level gets lower, the spacing becomes closer, so that the amount of advection is always constant regardless of whether the water level is up or down.

〔Example〕

Next, this invention will be explained in detail.

FIG. 1 is a sectional view of an embodiment of this invention, and FIG. 2 is a graph showing the operating state of the embodiment.

The sewage septic tank 1 of the present invention includes a tank IA that performs sedimentation separation or treatment using anaerobic microorganisms by leaving sewage still, a fluidized bed tank IB or contact aeration treatment tank IC that performs treatment using aerobic microorganisms, and a final treatment tank IC. It is equipped with a sedimentation tank ID to precipitate suspended sludge and a disinfection tank 1E to disinfect the discharged liquid, and the primary treated water is transferred from tank IA, which performs sediment separation or treatment using anaerobic microorganisms, to a subsequent treatment tank IB or IC by an air lift pump 2. In the sewage septic tank 1 that purifies sewage while adjusting the flow rate by forced advection of W, the air lift pump 2 is controlled to operate intermittently by a control device W3, and the intervals of the intermittent operation are shown in FIG. Pre-treatment tank IA
The water level is coarse at the upper limit water level HWL, and as the water level becomes lower, the intervals are made closer, so that the amount of advection is always constant regardless of whether the water level is up or down.

Note that two people in the figure represent near blowers that drive the air lift pump 2.

As shown in Fig. 2, the control mode of the control device 3 is such that at the highest water level HWL of the pre-treatment tank, the standby time S is long due to instantaneous driving, and as the water level decreases, the driving time t increases, and at the lowest water level When reaching LWL, the operation is stopped and a reset state is entered, and the above-mentioned operation is restarted again at the highest ice level HWL.

[Function] In the sewage septic tank 1 of the present invention, when the water level of the front-stage treatment tank IA reaches the highest level HWL and the amount of sewage received decreases, the control device 3 starts forced advection of the sewage to the rear-stage treatment tank.

At this time, at the highest water level (HWL), the driving time of the air lift pump 2 is short, but since the water level in the pre-treatment tank IA is high, the amount of transfer in one drive is large, and as the water level decreases, the driving time of the air lift pump 2 is Since the length is increased, the amount of transfer per unit time can be kept approximately constant, and overflow and short bath caused by a sudden rise in water level in the downstream treatment tank can be prevented.

〔effect〕

As explained above, in the sewage septic tank of the present invention, the amount of sewage transferred is kept constant on average by controlling the intermittent operation of the air lift pump, so the water level of the treated water in the downstream settling tank increases at a high rate. This prevents the discharge of untreated water.

[Brief explanation of drawings]

Figure 1 is a sectional view of an embodiment of this invention. Figure 2 is A graph showing the control state of the embodiment, Figure 3 is a conventional example '7/fD ? 2 [E]

Claims (1)

[Claims] (1) A tank that performs sedimentation separation or treatment using anaerobic microorganisms by leaving sewage still, a fluidized bed tank or contact aeration treatment tank that performs treatment using aerobic microorganisms, and a sedimentation tank that ultimately precipitates suspended sludge. A flow rate of a sewage septic tank, which is equipped with a tank and performs purification treatment of sewage while adjusting the flow rate by forcibly advecting the primary treated water from the tank where the treatment is performed using precipitation separation or anaerobic microorganisms to the downstream treatment tank using an air lift pump. In the adjustment method, the air lift pump is controlled to operate intermittently by a control device, and the interval between the intermittent operations is coarse when the water level of the pre-treatment tank is at the upper limit water level, and becomes closer as the water level decreases, regardless of whether the water level is up or down. A method for adjusting the flow rate of a sewage septic tank, characterized in that the amount of advection is kept constant at all times.