JPH0985289A - Waste water treatment apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a waste water treatment apparatus capable of accurately controlling the return flow rate of a nitration soln. and capable of keeping the return flow rate constant regardless of the fluctuations of the water level in a nitration tank. SOLUTION: In a waste water treatment apparatus equipped with a nitration soln. return means returning the nitration soln. in a nitration tank 2 to a denitrifying tank 1, the nitration soln. return means is equipped with a water wheel type storage pump 3 pumping up the treated water in the nitration tank 2, a water receiving tank receiving the treated water pumped up by the water wheel type storage pump 3, a nitration soln. return passage 4 and treated water sending-out passage 5 connected to the water receiving tank and a flow rate control means regulating the ratio of the flow rates from the water receiving tank to the nitration soln. return passage 4 and the treated water sending-out passage 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wastewater treatment apparatus, and more specifically, it is provided with a denitrification tank and a nitrification tank for removing nitrogen components in wastewater by biological nitrogen removal by a circulating nitrification denitrification method. It relates to a wastewater treatment device.

[0002]

2. Description of the Related Art A circulating nitrification denitrification method having a denitrification tank and a nitrification tank has been widely used as a method for removing nitrogen from wastewater. This circulation type nitrification denitrification method basically consists of a denitrification tank under anoxic conditions in the first stage and a nitrification tank under aerobic conditions in the second stage, and removes nitrate nitrogen and nitrite nitrogen produced in the nitrification tank. This is a treatment method in which the nitrification solution containing the nitrogen is returned to the denitrification tank in the previous stage and circulated, and brought into contact with raw water to denitrify.

Conventionally, a general pumping pump has been used as a means for returning the nitrification liquid from the nitrification tank to the denitrification tank, but in the circulation type nitrification denitrification method, it is usually returned from the nitrification tank to the denitrification tank. Since the amount of nitrification liquid to be used is set to about twice as much as the raw water, and about 6 times when it is large, the return flow rate of nitrification liquid is extremely large, the energy consumption of the pump is large, and it greatly affects the running cost. It was In addition, since the nitrification tank and the denitrification tank are usually provided at the same level, the performance of the pump itself (head and the like) is excessive, which has contributed to an increase in cost.

For this reason, the nitrification solution is also returned from the nitrification tank to the denitrification tank by utilizing the air lift effect of the aeration air in the nitrification tank. That is, by adding air bubbles generated from the air diffuser to the treated water in order to keep the nitrification tank under aerobic conditions, the apparent specific gravity of the treated water is reduced and the water level is increased by the amount corresponding to the specific gravity difference. By raising the water level in the nitrification tank to be higher than that in the denitrification tank, the treated water (nitrification solution) is made to flow down into the denitrification tank.

[0005]

However, the air bubbles supplied to the nitrification tank are for keeping the inside of the nitrification tank under aerobic conditions, and the pumping by the air lift effect is secondary. If the inflow or outflow of treated water changes only with the air lift effect, it may not be possible to secure a predetermined return flow rate, and the return flow rate is adjusted because the pumping rate is affected by the water level. There was also a problem that it was difficult.

Therefore, the object of the present invention is to provide a wastewater treatment apparatus capable of precisely controlling the return flow rate of nitrification liquid and keeping the return flow rate constant regardless of fluctuations in the water level in the nitrification tank. I am trying.

[0007]

In order to achieve the above object, a wastewater treatment apparatus of the present invention comprises a denitrification tank into which raw water and a nitrification liquid flow, and a nitrification tank into which the treatment water of the denitrification tank flows. In a wastewater treatment apparatus for biological nitrogen removal by a circulating nitrification denitrification method, a water wheel pumping pump is used as a nitrification solution returning means for returning the nitrification solution in the nitrification tank to the denitrification tank. Further, the nitrification liquid return means, in the water tank type pump pump for pumping the treated water in the nitrification tank, a receiving tank for receiving the treated water pumped by the water turbine type pump, and the receiving tank. A connected nitrification solution return flow path and a treated water delivery flow path, and a flow rate adjusting means for adjusting a flow rate ratio of the outflow from the water receiving tank to the nitrification solution return flow channel and the treated water delivery path, Preferably, the valve body moves horizontally to open and close. It is characterized by comprising a preparative valve.

The above-mentioned water turbine type pumping pump is disclosed in, for example, Japanese Patent Laid-Open Publication No. 50-140905 and Japanese Utility Model Laid-Open No. 53-113413.
As described in the publication, pumping water by rotating a wheel that has a liquid reservoir for pumping water on the circumference with a motor or the like, and it is difficult to raise the head, but during operation There is almost no blockage, and it is possible to easily change the pumping volume by adjusting the number of rotations of the wheel, which requires less power and has a higher pumping efficiency. It has performance suitable for pumping low head and large flow rate, such as easy management.

By using the above-mentioned water turbine type pumping pump, an appropriate amount of nitrification liquid can be efficiently returned, and nitrogen removal and wastewater treatment can be stably performed. Further, the return flow rate of the nitrification solution can be easily changed by providing a flow rate adjusting means for adjusting the flow rate ratio of the treated water (nitrification solution) flowing out from the receiving tank to the nitrification solution return flow channel and the treated water delivery flow channel. Also, by providing a gate valve that opens and closes by moving the valve body horizontally as the flow rate adjusting means, it is easy to see the ratio of the amount of water flowing from the water receiving tank to each flow path simply by looking at the open position of the valve body. Can be confirmed.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in more detail with reference to the drawings. FIG. 1 shows an example of a wastewater treatment apparatus to which the present invention is applied, FIG. 2 is a front view showing an example of a water turbine pumping pump, and FIG. 3 is a plan view of the same.

This wastewater treatment system comprises a denitrification tank 1 into which raw water and a nitrification liquid flow, a nitrification tank 2 into which the treatment water from the denitrification tank 1 flows, and a water pump pump 3 for pumping the treatment water in the nitrification tank 2. And a nitrification liquid return flow path 4 for returning the treated water pumped up by the water turbine pumping pump 3 to the denitrification tank 1, and a treated water delivery passage for delivering the pumped treated water to the next treatment step. 5 and.

At the bottom of the denitrification tank 1 for anaerobic treatment,
An underwater stirrer 11 is provided, and an air diffuser 21 is provided at the bottom of the nitrification tank 2 that performs aerobic treatment. A flow path 12 extending from the upper part of the denitrification tank 1 to the bottom of the nitrification tank 2 is provided between the denitrification tank 1 and the nitrification tank 2, and the water treated in the denitrification tank 1 is From the top of the nitrification tank 2
Flows into the bottom of the.

The water pump type pump 3 is shown in FIGS.
As shown in, the wheel 31 and the water receiving tank 32 are provided. The wheel 31 is provided on one side surface of the disk-shaped side plate 33.
An outer cylinder 34 having a diameter substantially equal to that of the side plate 33, an inner cylinder 35 having a smaller diameter than the outer cylinder 34, and a plurality of partition plates 36 for partitioning the outer cylinder 34 and the inner cylinder 35 at substantially equal intervals are provided. 33, an outer cylinder 34, an inner cylinder 35, and adjacent partition plates 36, 36 form a liquid reservoir 37 having an open front surface.

The water receiving tank 32 is provided adjacent to the front surface of the wheel 31, and the vertical dimension of the back plate 32a thereof reaches at least the uppermost portion or the lowermost portion by the rotation of the wheel 31. 37 are set so as to fully open above and below the back plate 32a, respectively, and further, at least on the rotation rising side of the wheel 31, the liquid reservoir 3
It is formed so that the front opening of 7 can be closed. The water level in the nitrification tank 2 is set to be higher than the lower end of the back plate 32a.

That is, the hydraulic pump 3 having the above structure
The water in the nitrification tank 2 flows into the liquid reservoir 37 located below the back plate 32a as the wheel 31 driven by the motor 38 rotates, and the liquid reservoir 37 moves upward. When doing so, the front opening of the liquid reservoir 37 is attached to the rear plate 32.
Water is retained in the liquid reservoir 37 by being blocked by a,
Further, when the wheel 31 rotates and the liquid reservoir 37 is located above the back plate 32a, the water in the liquid reservoir 37 flows down into the water receiving tank 32.

Further, in the water receiving tank 32, the nitrification solution return flow path 4 and the treated water delivery flow path 5 are connected to each other through gate valves 41 and 51, which are flow rate adjusting means, respectively. . The gate valves 41 and 51 include a valve body (gate) 42,
52 moves in the horizontal direction to open and close the valve ports 43 and 53, respectively, and the gates 42 and 52 rotate the gate opening and closing handles 44 and 54 to move through the rack and pinion parts 45 and 55. It is formed so as to open and close.

Thus, the gate valve 4 of the type in which the gates 42 and 52 move horizontally to open and close the valve ports 43 and 53.
By connecting the nitrification solution return flow path 4 and the treated water delivery flow path 5 via 1, 51, from the water receiving tank 32 to the nitrification solution return flow path 4 and the treated water delivery path 5. Since the ratio of the amount of flowing water can be adjusted by the opening ratio of the gates 42 and 52, the flow rate of the nitrification liquid returned from the nitrification tank 2 to the denitrification tank 1 can be easily set.

For example, since the amount of treated water sent from the treated water delivery passage 5 to the next treatment step is substantially the same as the amount of treated raw water flowing into the denitrification tank 1, the denitrification tank 2 is denitrified. When the amount of the nitrifying solution to be returned to 1 is set to be twice the treated raw water, the opening ratio of the gate valve 41 and the gate valve 51 is set to 2:
All you need to do is 1 (4: 2)
The aperture ratio may be 5: 1.

In the waste water treatment apparatus thus formed, the treated raw water that has flowed into the denitrification tank 1 from the dust remover, the first settling tank, etc., flows from the nitrification solution return flow path 4 to 2 to 6 times the amount of circulating nitrification. After being denitrified under oxygen-free conditions while being mixed with the liquid and being stirred by the underwater stirrer 11, while flowing into the nitrification tank 2 from the flow path 12 and being stirred by the air supplied from the air diffuser 21 It is nitrified by nitrifying bacteria under aerobic conditions.

Then, the treated water in the nitrification tank 2 is pumped to the water receiving tank 32 by the water wheel type pump 3, and the nitrification solution return flow path 4 and the treated water are sent from the water receiving tank 32 through the gate valves 41 and 51. By flowing the treated water into the flow path 5 at a predetermined flow rate ratio, the nitrification solution can be returned to the denitrification tank 1 at a stable flow rate as compared with the return flow of the nitrification solution using the air lift effect, and in general, Cost can be reduced compared to pumping pumps.

The water turbine pumping pump may be provided with a plurality of groups in series on both sides of the water receiving tank. Also, a distribution tank may be provided separately from the water receiving tank, and both flow paths may be connected to the distribution tank via respective flow rate control valves. For example, a plurality of water wheel pump pumps may be provided with the water receiving tanks, respectively.
The water in each water receiving tank may be collected in one distribution tank and then distributed to both channels via the flow rate control valve. Further, the flow rate adjusting means is not limited to the gate valve, and other types of valves, weirs, and the like can be used.

Further, it is also possible to construct such that the whole amount of the nitrification liquid pumped up by the water turbine type pump is returned to the denitrification tank without providing the treated water delivery passage, and a part of the nitrification liquid (return flow rate) is returned. The above nitrification solution) may be returned to the nitrification tank.
In this case, in order to send the treated water in the nitrification tank to the next treatment step, an appropriate outflow means such as an overflow may be provided.

Further, in order to adjust the ratio of the amount of water flowing through the nitrification liquid return flow path and the treated water delivery flow path, in the above embodiment,
Each was equipped with a gate valve, which is a flow rate control means.
The opening ratio of the valve opening may be changed by laterally moving the gates. That is, by continuously moving one gate from the state where one valve opening is fully open and the other valve opening is fully closed, one valve opening is continuously closed until the other valve opening is fully opened. It is also possible to use a flow rate adjusting means having a structure capable of changing the opening ratios of both valve openings.

[0024]

As described above, in the wastewater treatment apparatus of the present invention, the treatment liquid in the nitrification tank is pumped up by the water turbine type pump and returned to the denitrification tank. The liquid can be efficiently returned, and nitrogen removal and wastewater treatment can be performed stably. Further, the nitrification solution pumped by the water turbine pump is distributed from the water receiving tank through the flow rate adjusting means to the nitrification solution return flow path and the treated water delivery flow path at a predetermined flow rate, thereby returning the nitrification solution. The flow rate can be easily adjusted, and the processing efficiency can be improved.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing an example of a wastewater treatment device to which the present invention is applied.

FIG. 2 is a front view showing an example of a water pump type pump.

FIG. 3 is a plan view of the same.

[Explanation of symbols]

1 ... Denitrification tank, 2 ... Nitrification tank, 3 ... Water pump pump, 4 ...
Nitrification liquid return flow passage, 5 ... Treated water delivery flow passage, 11 ... Submersible stirrer, 21 ... Diffuser, 31 ... Wheel, 32 ... Water tank, 37 ... Liquid reservoir, 41, 51 ... Gate valve

Claims (3)

[Claims] 1. A wastewater treatment apparatus for biological nitrogen removal by a circulating nitrification denitrification method, comprising: a denitrification tank into which raw water and a nitrification liquid flow, and a nitrification tank into which treated water of the denitrification tank flows. A wastewater treatment device characterized in that a water pump pump is used as a nitrification solution returning means for returning the nitrification solution in the nitrification tank to the denitrification tank. 2. A denitrification tank into which raw water and a nitrification solution flow, a nitrification tank into which treated water of the denitrification tank flows, and a nitrification solution return means for returning the nitrification solution in the nitrification tank to the denitrification tank. In the wastewater treatment device for removing biological nitrogen by the circulation type nitrification denitrification method, the nitrification liquid returning means is a water wheel pump pump for pumping the treated water in the nitrification tank, and the water wheel pump pump. A water receiving tank for receiving treated water, a nitrification solution returning flow path and a treated water delivery path connected to the water receiving tank, a nitrification solution returning flow path from the water receiving tank, and the treated water delivery path And a flow rate adjusting means for adjusting a flow rate ratio of the wastewater flowing out to the wastewater treatment apparatus. 3. The wastewater treatment apparatus according to claim 2, wherein the flow rate adjusting means is a gate valve that opens and closes by moving a valve body in a horizontal direction.