JPH11104690A - Septic tank - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a septic tank capable of adjusting filtration quantity according to inflow quantity of raw water to a denitrification tank and reducing flow equalization capacity of the denitrification tank. SOLUTION: A permeated water pipe 25 of a membrane separation apparatus 22 is provided with a diverging pipe 29, and the permeated water pipe 25 and the diverging pipe 29 are provided with a first determinate flow valve 28 and a second determinate flow valve 31 respectively, and a magnet valve 30 is provided for opening and closing the diverging pipe 29. Thereby when inflow quantity of raw water 34 is great and a liquid level inside a denitrification tank 21 is high, filtration quantity inside a nitrification tank 23 is allowed to be large by the permeated water being introduced and discharged by the permeated water pipe 25 and the diverging pipe 29, and liquid 35 mixed with activated sludge inside the denitrification tank 21 and having a quantity according to the filtration quantity can be flowed into the nitrification tank 23 to shorten time of retention of the raw water in the denitrification tank 21.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a purification tank having a denitrification tank and a nitrification tank, wherein a membrane separation device is immersed in the nitrification tank.

[0002]

2. Description of the Related Art As a conventional purification tank, for example, there is a purification tank provided with a denitrification tank 1 and a nitrification tank 3 in which a membrane separation device 2 is immersed as shown in FIG. The membrane separation device 2 is configured by arranging tubular or flat membrane elements 2a, and is installed so that each membrane element 2a is located above the air diffuser 4, and the permeated water flow of each membrane element 2a The permeated water pipe 5 communicating with the passage is provided with the medicine tube 6 and the suction pump 7 therebetween, and is opened outside the septic tank.

In such a septic tank, the raw water 8 is supplied to the denitrification tank 1
Activated sludge mixture 9 in the denitrification tank 1 is introduced into the nitrification tank 3.
The activated sludge mixed liquid 10 in the nitrification tank 3 is returned to the denitrification tank 1 while flowing to the denitrification tank 1. In this state, the pollutants in the raw water 8 are denitrified in the denitrification tank 1 under anaerobic conditions, and are nitrified in the nitrification tank 3 under aerobic conditions where air is diffused from the diffuser 4. The activated sludge mixture 10 is filtered by the membrane element 2a by applying a suction pressure by the suction pump 7, and the permeated water permeates through the membrane surface of the membrane element 2a and flows into the permeated water flow path (not shown) inside the membrane element 2a. Is led to the outside of the septic tank through the permeated water pipe 5, and at that time, it is disinfected by being brought into contact with a solid chlorine agent or the like charged into the drug cylinder 6 in the conduit of the permeated water pipe 5.

[0004]

However, in the above-mentioned conventional septic tank, the suction pump 7 is usually driven at a constant speed to quantitatively filter the activated sludge mixture 10 in the nitrification tank 3. Therefore, even when a large amount of raw water 8 flows into the denitrification tank 1, the amount of the activated sludge mixed liquid 9 much larger than the designed amount cannot flow into the nitrification tank 3, so that a large amount of There is a problem that it is necessary to secure a large flow control capacity in case raw water flows in.

An object of the present invention is to solve the above-mentioned problems, and an object of the present invention is to provide a purification tank in which the amount of filtration can be adjusted in accordance with the amount of raw water flowing into the denitrification tank, and the flow rate adjustment capacity of the denitrification tank can be reduced. Is what you do.

[0006]

In order to solve the above-mentioned problems, a septic tank according to claim 1 of the present invention has a structure in which raw water flows,
A denitrification tank that performs anaerobic treatment, a nitrification tank in which the activated sludge mixed liquid in the denitrification tank flows in, and an aerobic treatment; and a membrane separation device that is immersed and installed in the nitrification tank to filter the activated sludge mixed liquid. A purification tank provided with a membrane permeate flow path of the membrane separation device, a permeate pipe provided with a suction pump, and a permeate pipe for guiding permeate flowing into the membrane permeate flow path out of the tank. A branch pipe communicating with the permeate pipe at a position downstream of the suction pump via an electromagnetic valve is provided, a first constant flow valve is interposed at a position downstream of the branch pipe branch part of the permeate pipe, and electromagnetic waves in the branch pipe are provided. A second constant flow valve is interposed at a position downstream of the valve, and a liquid level measuring means for measuring the liquid level of the activated sludge mixed liquid in the denitrification tank is provided, and the liquid level measuring means and the solenoid valve are electrically connected to each other. And a predetermined high and low liquid level measured by the liquid level measuring means. And control means for controlling the opening and closing of the solenoid valve.

A septic tank according to a second aspect of the present invention includes a denitrification tank in which raw water flows and performs anaerobic treatment, and a nitrification tank in which an activated sludge mixed liquid in the denitrification tank flows and performs aerobic treatment. A membrane separation device immersed and installed in the nitrification tank to filter the activated sludge mixed solution, and a membrane separation device provided in communication with the membrane permeate flow passage of the membrane separation device, and a suction pump interposed therebetween; In a septic tank provided with a permeated water pipe for guiding permeated water flowing out of the tank, a liquid level measuring means for measuring the liquid level of the activated sludge mixed liquid in the denitrification tank, and the liquid level measuring means and a suction pump. And a control means for controlling the suction pump by an inverter based on the liquid level measured by the liquid level measuring means and controlling the suction flow rate.

[0008] According to the configuration of the first aspect, the liquid level of the activated sludge mixed liquid in the denitrification tank is continuously or intermittently measured by the liquid level measuring means, and the measured liquid level is a predetermined level. When the liquid level is lower than the high liquid level, the branch pipe is closed by the control means and the solenoid valve, and the permeated water having a constant flow rate (hereinafter referred to as C1) defined by the first constant flow valve in the permeated water pipe is downstream. The flow and the amount of the activated sludge mixture in the nitrification tank corresponding to C1 are filtered.

In this state, when the liquid level in the denitrification tank rises and a predetermined high liquid level is measured, the branch pipe is opened by the control means and the solenoid valve, and the branch pipe is opened in the permeated water pipe.
(1) While the permeated water having the constant flow rate C1 defined by the constant flow valve flows downstream, the permeated water having the constant flow rate (hereinafter referred to as C2) defined by the second constant flow valve flows downstream in the branch pipe, The activated sludge mixture in the nitrification tank in an amount corresponding to C1 + C2 is filtered.

In this state, when the liquid level in the denitrification tank drops and a predetermined low liquid level is measured, the branch pipe is closed by the control means and the solenoid valve, and in the same manner as described above, In the permeated water pipe, the permeated water having a constant flow rate C1 defined by the first constant flow valve flows downstream, and an amount of the activated sludge mixture in the nitrification tank corresponding to C1 is filtered.

Such an operation is repeated. However, as described above, when the inflow of raw water is large and the liquid level in the denitrification tank is high, the amount of filtration in the nitrification tank is increased. A large amount of the activated sludge mixture in the denitrification tank can be sent to the nitrification tank to shorten the residence time of the raw water in the denitrification tank, and the flow rate adjustment capacity of the denitrification tank can be small.

According to the above configuration, the liquid level of the activated sludge mixture in the denitrification tank is continuously or intermittently measured by the liquid level measuring means, and the suction pump is controlled by the control means. By performing inverter control to a preset rotation speed corresponding to the measured liquid level, the suction flow rate is controlled to a predetermined value, and an amount of the activated sludge mixture in the nitrification tank corresponding to the suction flow rate is filtered.

[0013] Also in this configuration, when the flow rate of raw water is large and the liquid level in the denitrification tank is high, the amount of filtration in the nitrification tank is increased. The liquid can be sent to the nitrification tank to shorten the residence time of the raw water in the denitrification tank, and the flow control capacity of the denitrification tank can be small.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. As shown in FIG. 1, the septic tank according to the first embodiment of the present invention has substantially the same configuration as the conventional septic tank described above with reference to FIG.
Nitrification tank 23 immersed in denitrification tank 21 and membrane separation device 22
An overflow port 21a is formed between the denitrification tank 21 and the nitrification tank 23, and a transfer pipe 23a is guided from the nitrification tank 23 to the denitrification tank 21. The membrane separation device 22 is configured by arranging tubular or flat membrane elements 22 a, and is installed such that each membrane element 22 a is located above the air diffuser 24.

A permeated water pipe 25 communicating with a permeated water flow path (not shown) of each membrane element 22a is led to a discharge flow path (not shown) outside the septic tank. And a first constant flow valve 28. The permeated water pipe 25 also has a branch pipe 29 communicating at a position between the suction pump 27 and the first constant flow valve 28 and at a downstream position of the first constant flow valve. An electromagnetic valve 30 and a second constant flow valve 31 are interposed in order from the upstream side.

A liquid level measuring means such as a liquid level meter 32 is provided inside the denitrification tank 21. The liquid level meter 32 is connected to the solenoid valve 30 by lines L1 and L2.
Is provided with a control device 33 that controls the opening and closing of the solenoid valve 30 at a predetermined high liquid level HL and a low liquid level LL measured by the following equation.

The operation of the above configuration will be described. The raw water 34 is introduced into the denitrification tank 21, and the activated sludge mixture 35 in the denitrification tank 21 is allowed to flow to the nitrification tank 23 while
The activated sludge mixed liquid 36 having a predetermined liquid level or higher is returned to the denitrification tank 21 at a constant flow rate. And in this state, raw water 3
4 is denitrified under anaerobic conditions in a denitrification tank 21, nitrified in a nitrification tank 23 under aerobic conditions where air is diffused from a diffuser 24, and suction pressure is applied by a suction pump 27. The activated sludge mixture 36 is filtered by the membrane element 22a of the membrane separation device 22 by the action of.

At this time, the permeated water that has passed through the membrane surface of the membrane element 22a and has flowed into the membrane permeated water flow path inside the membrane element 22a is drawn out of the purification tank through the permeated water pipe 25. The liquid level of the activated sludge mixture liquid 35 is continuously or intermittently measured by the liquid level meter 32,
When the measured liquid level is lower than the high liquid level HL, the control device 3
3 and the permeated water pipe 25 is closed.
The constant flow rate C1 defined by the first constant flow valve 28
Permeate flows downstream, and the amount of nitrification tank 2 corresponding to C1
The activated sludge mixture 36 in 3 is filtered.

In this state, when the liquid level in the denitrification tank 21 rises and the high liquid level HL is measured, the solenoid valve 30 is opened by the control device 33 and the first constant flow valve 28 in the permeated water pipe 25 is opened. The permeated water having the prescribed constant flow rate C1 flows downstream, and the second constant flow valve 3
The permeated water having a constant flow rate C2 defined by 1 flows downstream, and the activated sludge mixture liquid 36 in the nitrification tank 23 corresponding to C1 + C2 is filtered.

In this state, when the liquid level in the denitrification tank 21 drops and the low liquid level LL is measured, the control device 33 closes the solenoid valve 30 and, similarly to the above, passes through the permeated water pipe 25. The permeated water having a constant flow rate C1 defined by the first constant flow valve 28 flows downstream, and an amount of the activated sludge mixture 36 in the nitrification tank 23 corresponding to C1 is filtered.

As described above, when the flow rate of the raw water 34 is large and the liquid level in the denitrification tank 21 is high, the amount of filtration in the nitrification tank 23 is increased, and the permeated water is led out of the purification tank. The activated sludge mixed liquid 35 in the denitrification tank 21 in an amount corresponding to the filtration amount flows into the nitrification tank 23, the raw water residence time in the denitrification tank 21 is shortened, and the flow control capacity of the denitrification tank 21 is smaller than in the past. Yes.

Incidentally, as the electromagnetic valve 30, a valve or the like which can maintain the permeate pipe 25 in an open state may be provided at a branch portion of the branch pipe 29 with respect to the permeate pipe 25. The septic tank according to the second embodiment of the present invention has a structure shown in FIG.
And the permeated water pipe 25 communicating with the permeated water flow path of each membrane element 22a is led to the discharge flow path outside the septic tank, A medicine tube 26 and a suction pump 27 are interposed in the middle of the road.

Inside the denitrification tank 21, there is provided a liquid level measuring means such as a liquid level meter 32 for measuring the liquid level of the activated sludge mixed liquid 35 in the tank. Are connected by lines L3 and L4. The controller 37 is configured to inverter-control the suction pump 27 based on the liquid level measured by the liquid level meter 32, and a designed amount of raw water flows in and a designed amount of permeated water is derived. Based on the liquid level and the suction pressure at the time, the rotation speed of the suction pump 27 is controlled so that the suction flow rate is increased or decreased at a predetermined rate as the liquid level rises or falls.

The operation of the above configuration will be described. No.
As in the case of the septic tank of the first embodiment, the activated sludge mixed liquid 36 in the nitrification tank 23 is generated by the suction pressure acting from the suction pump 27.
Is filtered by the membrane element 22a.
The permeated water that has passed through the membrane surface and flowed into the permeated water flow path inside thereof is led out of the septic tank through the permeated water pipe 25.

At this time, the liquid level of the activated sludge mixed liquid 35 in the denitrification tank 21 is continuously or intermittently measured by the liquid level meter 32, and when the high liquid level HL is measured, the high liquid level is measured. The suction pump 27 is controlled by the control device 37 so that the rotation speed becomes a preset rotation speed R1 with respect to the HL, and the permeated water having a flow rate Q1 corresponding to the rotation speed R1 is sucked.
An amount of activated sludge mixture 36 corresponding to 1 is filtered.

When the low liquid level LL is measured, a predetermined rotation speed R2 (<R1) for the low liquid level LL is used.
The control device 37 controls the suction pump 27 so that the permeated water having a flow rate Q2 (<Q1) corresponding to the rotation speed R2 is suctioned, and the activated sludge mixed liquid 36 having an amount corresponding to the flow rate Q1 is filtered. .

Also in this configuration, when the flow rate of the raw water 34 is large and the liquid level in the denitrification tank 21 is high, the amount of filtration in the nitrification tank 23 is increased, and the permeated water is led out of the purification tank. The amount of the activated sludge mixture 35 in the denitrification tank corresponding to the amount of filtration flows into the nitrification tank 23, the raw water residence time in the denitrification tank 21 is shortened, and the flow rate adjustment capacity of the denitrification tank 21 can be smaller than before. .

In the above description, the activated sludge mixture 35 in the denitrification tank 21 is allowed to flow into the nitrification tank 23 while
The activated sludge mixed liquid 31 in the nitrification tank 23 is transferred to the nitrification tank 23 at a constant flow rate while the activated sludge mixed liquid 31 in the inside is returned to the denitrification tank 21. The above-described configuration can also be applied to a purification tank in which 36 is allowed to overflow to the denitrification tank 21.

[0029]

As described above, according to the present invention, a branch pipe is provided in a permeated water pipe of a membrane separation apparatus, and a constant flow valve is interposed in each of the permeated water pipe and the branched pipe to open and close the branched pipe. By providing a large amount of raw water, when the liquid level in the denitrification tank is high, the permeated water is led out by the permeated water pipe and the branch pipe to increase the amount of filtration in the nitrification tank, and according to the amount of filtration. Amount of the activated sludge mixture in the denitrification tank can flow into the nitrification tank,
The flow control capacity of the denitrification tank can be designed to be small, and the septic tank can be made compact.

Further, by providing a control means for inverter-controlling the suction pressure of the suction pump based on the liquid level in the denitrification tank, a large amount of permeated water can be supplied when the raw water inflow is large and the liquid level in the denitrification tank is high. The amount of activated sludge mixed in the denitrification tank can be made to flow into the nitrification tank in an amount corresponding to the filtration amount by deriving the amount of filtration in the nitrification tank. It can be designed and the septic tank can be made compact.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a schematic overall configuration of a septic tank according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a schematic overall configuration of a septic tank according to a second embodiment of the present invention.

FIG. 3 is an explanatory diagram showing a schematic overall configuration of a conventional septic tank.

[Explanation of symbols]

 21 Denitrification tank 21a Overflow port 22 Membrane separator 22a Membrane element 23 Nitrification tank 25 Permeate pipe 27 Suction pump 28 First constant flow valve 29 Branch pipe 30 Solenoid valve 31 Second constant flow valve 32 Liquid level gauge 33 Control device 34 Raw water 35 Activated sludge mixture 36 Activated sludge mixture 37 Control deprivation

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Koichi Okada 1-1-1 Hama, Amagasaki-shi, Hyogo Inside Kubota Research Institute of Technology (72) Inventor Kazuyuki Honda 2 Takamatsu, Kosai-cho, Koga-gun, Shiga Prefecture 1 Kubota Shiga Plant

Claims (2)

[Claims] 1. A denitrification tank in which raw water flows in to perform anaerobic treatment, an activated sludge mixed liquid in the denitrification tank flows in, and a nitrification tank in which aerobic treatment is performed. A membrane separation device for filtering the sludge mixture, provided in communication with the membrane permeated water flow path of the membrane separation device, with a suction pump interposed,
A purifying tank provided with a permeated water pipe for guiding permeated water flowing into the membrane permeated water flow path to the outside of the tank, wherein a branch pipe communicating with a suction pump downstream of the permeated water pipe via an electromagnetic valve is provided; A first constant flow valve is interposed at a position downstream of the branch pipe branch portion in the above, a second constant flow valve is interposed at a position downstream of the solenoid valve in the branch pipe, and an activated sludge mixed liquid in the denitrification tank is provided. A liquid level measuring means for measuring the liquid level is provided, and is electrically connected to the liquid level measuring means and the solenoid valve, and electromagnetically measures at predetermined high and low liquid levels measured by the liquid level measuring means. A septic tank provided with control means for controlling opening and closing of a valve. 2. A denitrification tank in which raw water flows and performs an anaerobic treatment, an activated sludge mixed liquid in the denitrification tank flows in and a nitrification tank which performs an aerobic treatment, A membrane separation device for filtering the sludge mixture, provided in communication with the membrane permeated water flow path of the membrane separation device, with a suction pump interposed,
In a purification tank provided with a permeated water pipe for leading permeated water flowing into the membrane permeated water flow path to the outside of the tank, a liquid level measuring means for measuring a liquid level of the activated sludge mixed liquid in the denitrification tank, and the liquid level measurement A purification unit electrically connected to the means and the suction pump, and a control means for controlling the suction flow rate by inverter-controlling the suction pump based on the liquid level measured by the liquid level measurement means.