JPS5916596A - Removal device for excess sludge - Google Patents

Abstract

PURPOSE:To make the amt. of the sludge to be accumulated in each basin uniform, by determining the deviation value of the flow rate of the return sludge from each basin from the flow rate of the return sludge to be returned with a return sludge pump from the respective basin of a final settling basin and removing the excess sludge in accordance with the results thereof. CONSTITUTION:The activated sludge scraped by a sludge scraper 3 in, for example, four sludge accumulating inlets 2 in a settling basin 1 is returned by a return sludge pump 4 into an aeration tank, and the flow rates of the return sludge removed from the inlets 2 are measured with electromagnetic flowmeters 5 for return sludge. The excess sludge is branched from the removal pipings of the respective sludge accumulating inlets and is removed through electrically driven selector valves 6 provided for each of the basins by means of an excess sludge pump 7. The removal flow rate of the excess sludge in this stage is measured with an electromagnetic flowmeter 8 for the excess sludge. When a removal command is emitted to an excess removal command 9 in such constitution, the command is inputted to a calculator 10.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an excess sludge extraction device for extracting excess sludge accumulated in a final settling tank in a water treatment facility using an activated sludge method.

[Technical background]

Normally, the final settling tank is divided into nine sections, each consisting of two or more ponds, and each pond has a sludge scraping machine that scrapes the sludge into one sludge collection basin.

The return sludge pump is commonly installed for each sludge accumulation basin, and its operation is continuously controlled so that the total flow rate of the sludge drawn out from the sludge accumulation basin should match a preset return sludge target amount. Common.

On the other hand, the operation of the surplus sludge removal pump is by quantitative drawing using a time scheduler, and since this equipment is common to each sludge accumulation material, it is set in advance to pull out all sludge accumulation materials at the same time. This is an intermittent operation that ends when the target total withdrawal amount is reached.

Conventionally, the return sludge pump was operated based on the total return sludge flow rate as described above, and the drawing deviation amount for each pond was not considered a problem.

However, according to this operation, for example, the piping resistance loss from the sludge collection basin for each pond to the return sludge pump will inevitably occur due to the pump arrangement, the length and structure of the piping to the sludge output point of the six ponds, and the structure. The amount of loss is not uniform for each sludge collection basin. As a result, deviations occur in the amount of return sludge drawn from each pond that is continuously drawn by the return sludge pump, etc.
The amount of sludge extracted from ponds with high losses is extremely low (9), which leads to the accumulation of surplus sludge, which eventually leads to sludge flowing out of the final settling tank as sludge flocs.

[Summary of the invention]

The present invention consists of a sedimentation tank divided into a plurality of ponds for treating water with activated sludge, a sludge accumulating material installed in each of these settling basins for accumulating sludge, and a sludge accumulating material installed in the settling basin to scrape sludge into the sludge accumulating material. A sludge scraper that collects sludge, a return sludge pump that sends the sludge collected on the sludge accumulating material back to the aeration tank, and a sludge collected on the sludge accumulating material that does not need to be returned to the aeration tank. an electric switching valve for removing surplus sludge, which has one end connected to the surplus sludge pump and the other end connected to a sludge accumulating material or a pipe that has been pulled out from the sludge accumulating material; In the surplus sludge extraction equipment, which consists of an α magnetic flowmeter connected to the distribution system and which measures the total flow rate of the extracted surplus sludge, and a control device that controls the opening and closing of the electric switching valve and the operation of the surplus sludge pump. , a return sludge electromagnetic flowmeter that measures the flow rate of the returned sludge that is connected to the sludge accumulation material at one end and a return sludge pump at the other end, and the deviation value of the return sludge flow rate measured by these return sludge electromagnetic flowmeters. This surplus sludge extraction device is equipped with a computing unit that calculates and outputs the amount of surplus sludge to be extracted by the surplus sludge pump to a control device.

That is, the present invention calculates the deviation t' of the return sludge flow rate of the 6 ponds from the return sludge flow returned by the return sludge pump from the 6 final settling tanks, and from this result, the surplus sludge that is extracted by the surplus sludge pump. This is an excess sludge extraction device that determines the amount of sludge to be extracted.

Since the present invention is configured as described above, it is possible to perform excess sludge extraction control that averages the sludge accumulated as a deviation of the withdrawal flow rate due to return sludge withdrawal from the six ponds, and the surplus sludge is transferred to the final settling tank as sludge flocs. This has the effect of preventing sludge from flowing out overflow.

[Embodiments of the invention]

Next, the present invention will be explained in detail. The drawing shows a sedimentation tank J that is divided into multiple ponds and processes water using activated sludge, a sludge accumulation material 2 installed in the sedimentation tank 1 that collects sludge, and a sludge accumulation material 2 installed in the sedimentation tank 1 that collects sludge. A sludge scraper 3 that collects sludge, a return sludge pump 4 that sends the sludge collected on the sludge accumulating material 2 back to the aeration tank, and the sludge accumulated on the sludge accumulating material 2 does not need to be returned to the aeration tank. A surplus sludge pump 7 that pulls out surplus sludge, and a pipe 2a whose one end is connected to the surplus sludge pump 7 and whose other end is drawn out from the sludge accumulating material 2 or the sludge accumulating material 2.
An electromagnetic flow meter 8 connected to the piping system of the surplus sludge pump 7 for measuring the flow rate of the extracted surplus sludge, and an electric switching valve 6 for controlling the opening and closing of the electric switching valve 6 and for controlling the surplus sludge. A control device 11 that controls the operation of the sludge pump 7.
13, a return sludge electromagnetic flow meter 5 which is connected to the sludge accumulating material 2 at one end and the return sludge pump 4 at the other end and measures the flow rate of the return sludge to be drawn; and a return sludge electromagnetic flow rate meter 5. 5 shows an excess sludge extraction device equipped with a calculator 10 that calculates the deviation value of the return sludge flow rate measured by the total 5 and outputs the amount of excess sludge extracted by the excess sludge pump 7 to the control device 11. .

In the settling tank 1, for example, activated sludge is sent to the sludge collection basins 2 of four ponds by the sludge scraper 3, and the collected activated sludge is sent to the return sludge pump 4.
The amount of returned sludge drawn out from each sludge collection basin 2 to be returned to the aeration groove is measured by a magnetic flow pointer 5 in the returned sludge 1.

On the other hand, excess sludge is transferred to multiple branches from the extraction piping of each sludge collection basin, passed through the electric switching valve 6 installed in each bank, and then passed through the excess sludge pump 7.
It is pulled out. At this time, the surplus sludge extraction flow rate is measured by the surplus sludge electromagnetic flow meter 8.

In such a configuration, when a withdrawal command is issued by the surplus withdrawal command 9, it is input to the arithmetic unit 0.

The calculation unit 10 integrates the total amount of sludge returned to each bank from the previous extraction command to the current extraction command, and combines this value with the preset surplus sludge extraction total target flow rate ΣQs.
A target value ΔQs of the flow rate of excess sludge on the pond surface to be extracted as excess sludge from each pond is calculated and given to the controller 11. The controller 11 inputs a control signal 12 to the sequence controller 13 when the excess sludge extraction measured by the A4 magnetic flow meter 8 matches the target value of the surplus sludge extraction flow rate of the local bank. Based on this command, the electric switching valve 6 for excess sludge removal is switched to shift to the secondary pond extraction, and the same process is carried out until the final extraction, and the excess sludge pump is stopped and the switching valve is fully closed. Tonanashi waits until the next surplus sludge removal Iji 4 start command is issued.

The calculator 10 performs the following calculations.

± value Qs: Surplus sludge withdrawal flow rate target value QRI: Return sludge flow cap integrated value for the 1st pond (previous surplus withdrawal command) Q old: Accumulated return sludge flow rate for the 2nd pond (~current surplus withdrawal command) m details) Qim: Integrated value of return sludge flow rate from No.3 pond QR42 No.4
Since the deviation value of the return amount can be obtained from the integrated value of the return sludge flow rate from the ponds, that is, the integrated result of the return amount of the six ponds, the value obtained by multiplying the reciprocal proportional value by the preset excess sludge withdrawal flow rate target value is calculated. A target value of the flow rate for excess sludge removal from each pond is determined, such that a proportion of the excess sludge from ponds with a large number of returned sludges is removed from ponds with few returned sludges.

[Brief explanation of drawings]

The drawings are explanatory diagrams showing one embodiment of the present invention. 1... Sedimentation pond 2...Sludge collection basin 3...Sludge scraping machine 4...Return sludge pump 5...Return sludge '9L magnetic flowmeter 6...Excess sludge removal electric switching valve 7... Surplus sludge pump 8... Surplus sludge electromagnetic flowmeter 10... Arithmetic unit 11...Controller 13...Sequence controller

Claims (1)

[Claims] A sedimentation basin divided into a plurality of ponds for treating water with activated sludge, a sludge collection basin installed in each of these sedimentation basins for accumulating sludge, and a sludge accumulation basin installed in the sedimentation basin for collecting sludge into the sludge accumulation basin. A sludge scraping machine, a return sludge pump that sends the sludge collected in the sludge accumulation basin back to the aeration tank, and a sludge collecting machine that collects surplus sludge that does not need to be returned to the aeration tank. an excess sludge pump for extracting sludge; an electric switching valve for extracting excess sludge, one end of which is connected to the excess sludge pump and the other end connected to the sludge collection basin or a pipe drawn out from the sludge collection basin; an electromagnetic flowmeter connected to the piping system of the surplus sludge pump and measuring the flow rate of the extracted surplus sludge;
In the surplus sludge extraction device comprising a control device for controlling the opening/closing of the movable shut-off valve and controlling the operation of the surplus sludge pump, one end is connected to the sludge storage tank and the other end is connected to the return sludge pump. A return sludge electromagnetic flowmeter that is connected and measures the total flow rate of the return sludge to be drawn out, and a deviation value of the return sludge flow rate measured by these return sludge electromagnetic flowmeters is calculated and extracted by the surplus sludge pump. An apparatus for extracting excess sludge, comprising a computing unit that outputs the amount to the control device.