JP2515256B2 - Automatic adjustment device for sludge concentration in sewage treatment tank - Google Patents

Description

Description: TECHNICAL FIELD [0001] The present invention relates to a method and an apparatus for automatically adjusting sludge concentration in a sewage treatment tank.

[Background of the Invention]

In order to keep the treatment efficiency high in activated sludge treatment, a certain amount of microorganisms working on the inflow raw water to be treated is required. Conventionally, in continuous treatment such as the activated sludge method, a preliminary storage tank, etc. is provided to keep the inflow load into the treatment tank constant, and the sludge concentration is regularly measured to keep the sludge concentration constant. A certain amount of sludge is discharged as excess sludge out of the system. This includes JIS
MLSS using the dry weight method for suspended substances specified in
Alternatively, measure the MLVSS or measure the concentration of the treatment tank liquid using a photoelectric densitometer, and if the concentration is high, reduce the amount of sludge returned from the sedimentation tank, and change the sludge volume ratio discharged as excess sludge. Increase it.

However, in the activated sludge method for the purpose of denitrification, the sludge must be carefully extracted in order to keep the nitrifying bacteria in the treatment tank or the nitrification tank. Especially in the intermittent aeration automatic operation method (Patent No. 1160241) in which the sludge settling speed is used as an index of aeration and non-aeration, it is an essential requirement to keep the sludge concentration within a certain range.

[Object of the Invention]

An object of the present invention is to constantly maintain a constant sludge microorganism in a treatment tank liquid, reduce the amount of excess sludge, and automatically adjust the sludge concentration suitable for intermittent aeration conditions.

[Structure of Invention]

The apparatus for automatically adjusting the sludge concentration in the sewage treatment tank according to the present invention has a sewage treatment tank for performing aeration or stirring, and a sludge concentration adjustment tank for performing aeration as well as a precipitation action, From the lower part of the sewage treatment tank, a pump is attached to the pipeline that is led out from the lower part of the sewage treatment tank and has its leading end opening to the upper part of the sewage treatment tank. A sludge transfer mechanism is constructed by attaching a pump to the pipeline that is led out and introduced into the sludge adjusting tank, and is led out from the lower part of the sludge concentration adjusting tank to the upper part inside the wastewater treatment tank. A sludge reduction mechanism is constructed by attaching a pump to the opened pipe, and the upper part of the sludge concentration adjusting tank is used to overflow the supernatant water into the wastewater treatment tank when the water level of the sludge concentration adjusting tank rises. A clear water overflow channel is provided and sewage treatment When the sludge concentration in the sewage treatment tank is judged to be higher than the specified concentration by the transmission type optical sensor inside or in the circulation circuit of the sludge, the sludge transfer mechanism is activated by the pump, and also in the sewage treatment tank. When the sludge concentration is determined to be lower than a predetermined concentration, the pump is electrically connected so that the sludge reducing mechanism is operated.

〔Example〕

In the drawings of the embodiments, 1 is a sewage treatment tank, 1a is a device for aerating or stirring the sewage treatment tank 1, and 2 is a pump 4 in a pipe line 3 opened in the upper part of the sewage treatment tank 1. A sludge circulation circuit to be equipped, 5 is a sedimentation tank type sludge concentration adjusting tank, 5a is a device for aerating the sludge concentration adjusting tank 5, and 6 is a high concentration sludge from the lower part in the sludge adjusting tank 1. A sludge transfer mechanism for transferring the sludge to the sludge concentration adjusting tank 5, and a pump 4b is attached to the pipeline 3b which is led out from the lower part of the wastewater treatment tank 1 and introduced into the sludge concentration adjusting tank 5. It is composed of Reference numeral 8 is a supernatant water overflow channel which is led out from the upper part in the sludge concentration adjusting tank 5 and has its outlet opening end opened into the wastewater treatment tank 1, and clears the supernatant water when the water level in the sludge concentration adjusting tank 5 rises. It has a role of overflowing into the sewage treatment tank 1. Reference numeral 9 denotes a sludge return mechanism for reducing the settled sludge in the lower part of the sludge concentration adjusting tank 5 into the sewage treatment tank 1.
A pump 11 is provided in a pipe 10 which is led out from a lower part in the sludge concentration adjusting tank 5 and whose leading end is opened to an upper part in the sewage treatment tank 1. 12 is a discharge channel led out from the lower part of the sludge concentration adjusting tank 5, 13 is a pump for discharging excess sludge from the lower part of the sludge concentration adjusting tank 5 by the discharge channel 12, and 14 is the inside of the wastewater treatment tank 1. Alternatively, a transmission type optical sensor provided in the sludge circulation circuit, wherein when the optical sensor 14 determines that the sludge concentration in the wastewater treatment tank 1 is higher than a predetermined concentration, the sludge transfer mechanism by the pump 4 6
Is activated, and when the sludge concentration in the sewage treatment tank 1 is determined to be lower than a predetermined concentration, the sludge reduction mechanism 9 by the pump 11 is electrically connected so as to be activated. Reference numeral 15 is a tap water supply valve that opens when the water level in the sludge concentration adjusting tank 5 drops, and 16 is set to a level slightly lower than the constant water level in the sludge concentration adjusting tank 5. These are the water level detectors, and after these settled sludge is returned from the lower part of the sludge concentration adjusting tank 5 into the wastewater treatment tank 1, the water level in the sludge concentration adjusting tank 5 is restored to the constant water level and the next This is to prepare for the adjusting action.

After performing intermittent aeration in the sewage treatment tank 1, the sludge is precipitated and the supernatant water is discharged, and when the intermittent aeration process is performed again, the concentration is adjusted at a predetermined low water level l _0. The liquid in the tank is made uniform by the stirring device 1a,
The liquid in the tank is circulated through the circulation circuit 2 by driving the pump 4, and the sludge concentration is detected by the transmission type optical sensor 14 set in the sewage treatment tank 1 or in the middle of the circulation circuit 2,
When the concentration is higher than a predetermined value, the pump 4b is driven to cause the sludge transfer mechanism 6 to flow all or part of the circulating liquid into the sludge concentration adjusting tank 5. At this time, in the sludge concentration adjusting tank 5, intermittent or continuous aeration synchronized with the sewage treatment tank 1 is performed except for the concentration adjusting time, and the aeration is stopped during the concentration adjusting time. As a result, the sludge concentration adjusting tank 5 is in a stationary sedimentation time for about 1 to 3 hours, and during the sludge adjusting time, the sludge particles in the sludge mixture transferred into the sewage treatment tank 1 are sludge. The sedimentation occurs in the lower part of the concentration adjusting tank 5, and the supernatant water flows into the wastewater treatment tank 1 through the supernatant water overflow channel 8 as overflow.

While the supernatant water from which the sludge has been removed in this way is refluxed, while the high-concentration sludge is continuously transferred from the lower part of the sewage treatment tank 1 into the sludge concentration adjusting tank 5, the inside of the sewage treatment tank 1 The sludge concentration gradually becomes low, and is diluted until it reaches a predetermined concentration detected by the transmission type optical sensor 14.

Further, when the amount of sludge in the sewage treatment tank 1 decreases, the pump 11 of the sludge reduction mechanism 9 operates according to the detection signal of the transmission type optical sensor, and sedimentation occurs in the lower part of the sludge concentration adjusting tank 5. The thick sludge is returned to the sewage treatment tank 1 and is continued until the transmission optical sensor 14 detects that the sludge concentration in the sewage treatment tank 1 has reached a predetermined value.

When the water level in the sludge concentration adjusting tank 5 is lowered due to the continuation of the sludge transfer, the tap water supply valve 15 is opened by the detection signal of the water level detector 16 to supply water to the constant water level and to supply water to the next water level. In preparation for the adjusting action of.

〔The invention's effect〕

According to the present invention, when the growth rate of sludge microorganisms in the sewage treatment tank is large, the sludge is drawn out and stored in the sludge concentration adjusting tank, and when the concentration decreases due to self-digestion, the sewage is discharged from the sludge concentration adjusting tank. By replenishing the sludge to the treatment tank, the sludge concentration in the wastewater treatment tank can be adjusted, and there is an advantage that a certain amount of sludge microorganisms can be always retained in the liquid in the wastewater treatment tank.

In addition, in the sludge concentration adjustment tank, the amount of sludge is reduced by performing intermittent aeration without adding a substrate that is a nutrient source for microorganisms in addition to the extraction sludge, reducing the amount of excess sludge and intermittent aeration conditions. The activation of adapted sludge microorganisms is embodied. Thereby, microorganisms most suitable for replenishment into the sewage treatment tank can be obtained, and methane gas or the like can be generated by anaerobic fermentation to prevent the concentrated sludge from expanding and floating.

The method and apparatus of the present invention are not only required for automatic intermittent aeration control, but also play a large role in, for example, small-scale wastewater treatment tanks and recreational facility wastewater treatment tanks with large fluctuations in inflow load. The method is useful for all biological suspension treatment methods such as the oxidation method, oxidation date method, and oxidation pond method, and can contribute to automation, unmanned operation, and energy saving of equipment. It is.

[Brief description of drawings]

The drawing shows a longitudinal sectional view of one embodiment of the device of the present invention. 1 ... sewage treatment tank, 2 ... circulation circuit, 3 ... pipe, 3b ...
... Pipe line, 4 ... Pump, 4b ... Pump, 5 ... Sludge concentration adjusting tank, 6 ... Sludge transfer mechanism, 8 ... Supernatant water overflow channel, 9
…… Sludge reduction mechanism, 10 …… Pipeline, 11 …… Pump, 14 ……
Transmissive optical sensor.

Claims (2)

(57) [Claims] 1. A sewage treatment tank (1) having an aeration or stirring action and a sludge concentration adjusting tank (5) having a precipitation action, which is led out from a lower portion in the sewage treatment tank (1). Inside the sewage treatment tank (1), a pump (4) is attached to a pipe line (3) with its leading end opening to the upper part of the sewage treatment tank (1) to form a sludge circulation circuit (2). A sludge transfer mechanism (6) is constructed by attaching a pump (4b) to the pipeline (3b) that is led out from the lower part of the sludge and introduced into the sludge adjustment tank (5), and the sludge temperature adjustment tank (5) A sludge reduction mechanism (9) is constructed by attaching a pump (11) to a pipeline (10) that is led out from the lower part of the pipe and has its leading end opened to the upper part in the wastewater treatment tank (1). In the upper part of the sludge concentration adjusting tank (5), when the water level in the sludge concentration adjusting tank (5) rises, supernatant water is added to the wastewater treatment tank (1). A clear water overflow channel (8) for overflowing is provided, and a transmission type optical sensor (14) is provided in the wastewater treatment tank (1) or in the sludge circulation circuit (2) to provide the optical sensor ( When the sludge concentration in the sewage treatment tank (1) is determined to be higher than the predetermined concentration by 14), the sludge transfer mechanism (6) is operated by the pump (4), and the sewage treatment tank (1) When it is determined that the sludge concentration in) is lower than the predetermined concentration, the sludge reduction mechanism (9) is electrically connected by the pump (11).
Automatic adjustment device for sludge concentration in the sewage treatment tank. 2. A sewage treatment tank (1) which is aerated or stirred and a sludge concentration adjusting tank (5) which is aerated and settled, and is led from a lower part in the sewage treatment tank (1). Then, a pump (4) is attached to a pipeline (3) having an outlet end thereof opened upward in the wastewater treatment tank (1) to form a sludge circulation circuit (2). ) Pipe line (3b) led out from the lower part inside and introduced into the sludge adjusting tank (5)
A sludge transfer mechanism (6) is configured by attaching a pump (4b) to the sludge, and the sludge concentration adjusting tank (5) is led out from the lower portion and the leading end portion thereof is directed to the upper portion in the wastewater treatment tank (1). A sludge reduction mechanism (9) is configured by attaching a pump (11) to the opened pipeline (10), and the sludge concentration adjusting tank (5) is provided with an upper portion above the sludge concentration adjusting tank (5). An upper overflow channel (8) for overflowing the clear water into the sewage treatment tank (1) when the water level rises is provided, and a permeation type is provided in the sewage treatment tank (1) or the sludge circulation circuit (2). Light sensor (1
When the sludge concentration in the sewage treatment tank (1) is determined to be higher than a predetermined concentration by the optical sensor (14) equipped with the 4), the sludge transfer mechanism (6) is activated by the pump (4). When the sludge concentration in the sewage treatment tank (1) is determined to be lower than a predetermined concentration, it is electrically connected by a pump (11) so that the sludge reduction mechanism (9) is activated. Automatic adjustment device for sludge concentration in the sewage treatment tank.