JPS608880B2 - Wastewater treatment method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a wastewater treatment method for biologically treating organic wastewater.

Generally, biological treatment methods for organic wastewater include the floating activated sludge method and the pump circulation catalytic oxidation method.As a preliminary step, raw water storage control is performed to store the raw water of organic wastewater while preventing its decay. There is a tank.

This raw water storage adjustment tank (hereinafter referred to as the raw water tank), the aeration tank using the floating activated sludge method (hereinafter referred to as the aeration tank), and the contact oxidation tank using the pump circulation type contact oxidation method (hereinafter referred to as the aeration tank)
(hereinafter abbreviated as contact oxidation tank) means, for example, raw water tank -
When organic wastewater is treated by connecting the aeration tank and contact oxidation tank in this order, or when the wastewater concentration is low, the intermediate aeration tank can be omitted and the raw water tank and contact oxidation tank are connected to process the wastewater. There is something to do. Conventionally, as the above-mentioned raw water tank, moat tank, and contact oxidation tank, structures shown in FIGS. 1, 2, and 3 are known. FIG. 1 shows the raw water tank. In the figure, reference numeral 1 denotes a raw water tank. This raw water tank 1 contains raw water 2, and an aeration part 3 is provided in the lower part of the raw water tank 1. Air is supplied to the aeration section 3 from a blower 4 via an aeration pipe 5, and is blown into the raw water 2 from the aeration □3a. Reference numeral 7 is a bypass pipe for discharging excess air, and reference numerals 8 and 9 are valves. Further, numeral 10 is inflow raw water, and 11 is outflow raw water. Here, the purpose of circulating air into the raw water 2 is to
This is to prevent spoilage and to prevent artificial mixing. Figure 2 shows an explosive tank. Reference numeral 20 is an aeration tank, and this aeration tank 2 is filled with a mixed liquid 21.
An air diffuser 22 having an air diffuser □ 22a is provided at the inner lower side. The aeration section 22 has a raw water tank 1 shown in FIG.
As in the case of , the valve 24 and the blower 25 are connected in this order via the aeration pipe 26, and the valve 24 and the blower 25 are connected in this order through the aeration pipe 26.
A surplus air bypass pipe 27 is provided between the air blower 4 and the blower 25. In addition, the code|symbol 28 is a valve, L29 is inflow waste water, and 30 is an aeration tank processing mixed liquid. Here, the mixed liquid 21 contains activated sludge, and as air flows into the mixed liquid 21 from the holes 22a of the aeration section 22, oxygen is supplied, and the flies in the mixed liquid 21 , together with the circulation, the wastewater 29 is treated. FIG. 3 shows a catalytic oxidation tank, and reference numeral 40 is a catalytic oxidation tank. In the center of this contact oxidation tank 40, a filler 4 made of a plastic molded product, a nonwoven silk-like product, etc., is used to fix microorganisms.
1 is installed. Reference numeral 42 indicates inflow wastewater, and this inflow wastewater 42 is supplied to the contact oxidation tank 40 and becomes wastewater 43 in the pot.

This in-tank wastewater 43 passes through the filling material 41 and heads toward a draining section 44 having a large number of suction ports 44a provided at the bottom of the filling material 41. In-tank wastewater 43 sucked into the circulation pipe 46 from the liquid draining part 44 by the pump 45
faces the discharge part 47, and the discharge part 47a of this discharge part 47
It is being discharged from the water to the Naranai water surface. The tank wastewater 43 that has been treated through this circulation process becomes treated water 48 and is discharged outside the tank. By the way, if the raw water tank 1 and the aeration tank 20 are to use the same aeration device consisting of an air blower, a flow rate control device, etc., the amount of aeration will change depending on the raw water storage level.

On the other hand, since the water level in the aeration tank 20 is always constant, it is not preferable for the aeration tank 2 to have the amount of aeration changed as described above. Therefore, for raw water tank 1 and aeration tank 20,
It becomes necessary to provide a separate blower for each tank, and therefore, conventionally, in the raw water tank 1, a blower having the blowing capacity required when the tank is full of water is selected and installed. However, in the above-mentioned conventional raw water generator 1 and 4, when the water level in the raw water tank 1 decreases, the amount of stored raw water decreases and the amount of aeration decreases, but the amount of air blown depends on the discharge pressure of the blower. decreases, but instead increases, resulting in the blowing of excess air. In this way, the raw water tank 1 for vegetables has the disadvantage of wasting energy. Further, in general, when treating wastewater by the activated sludge method, the required oxygen amount 02 [k9/day] is roughly calculated by the following formula.

02 = aL + bS Here, L: Amount of BOD removed [k9/day] S = MLSS [k9] (amount of sludge) a'b: Coefficient Here, taking domestic wastewater (sewage) throughout the day as an example, The amount and quality of inflow water change as shown in Figure 4.

Generally, measures are taken to suppress this fluctuation to a certain extent by installing a raw water tank 1 in front, but this is not sufficient, and the amount and quality of water used generally differs between summer and winter. Furthermore, the sludge concentration (MBS) in the aeration tank actually varies in the range of 2,000 to 4,000 blood.
The blower 25 is installed with enough capacity to operate under conditions close to the maximum concentration of contaminants in the inflow water, so in reality, it can be operated under 1/salt of the blowing capacity for a sufficient period of time. This results in a relatively high proportion of cases. Therefore, if the excess air is not released outside the tank, the inside of the tank will become over-aerated, which will worsen the properties of microorganisms and reduce the wastewater treatment capacity. Therefore, most of the air is normally released into the atmosphere through the bypass pipe 27, and the amount of air released is 10 to 45% of the amount of air actually blown into the aeration tank 27.
Like Kawama and Raw Water Tank 1, it has the disadvantage of wasting energy. In the catalytic oxidation method, methods for supplying oxygen include, as mentioned above, a method that uses oxygen absorption from the surface of the rice cake through pump circulation (Figure 3), a method that uses oxygen absorption from bubbles using air diffusion, and a method that uses surface aeration. However, if oxygen is supplied only by pump circulation, the power consumption of the pump will inevitably increase, which is economically disadvantageous.

This invention was made in view of the above circumstances, and its purpose is to make it possible to effectively utilize one or both of the surplus air released from the raw water tank or the aeration tank, thereby increasing the efficiency of the contact oxidation tank pump. Our objective is to provide a method for treating organic wastewater that reduces power consumption and achieves overall energy savings. By using the above air as diffused air or by introducing the excess air into an injector installed in the middle of the circulation piping of the contact oxidation tank, oxygen is dissolved in the wastewater in the tank, and dissolved oxygen (Do) in the contact oxidation tank is dissolved. One or more of the following: a Do meter to detect the same pH, a pH meter to detect the same pH, and a flow rate meter to detect the flow rate in the filling material in the tank, or a combination of two or more of these are installed in the tank, and the above-mentioned A control circuit is installed to detect the value detected by a Do meter, etc., and a command from this control circuit is sent to the pump motor, and by adjusting the rotation speed of this motor, the circulating flow rate is controlled, resulting in overall energy savings. It is measured by

The present invention will be explained below with reference to the drawings.

5 and 6 show an embodiment of the present invention. In these figures, the same reference numerals as in FIGS. 1 to 3 indicate the same components, and the explanation thereof will be omitted. Figure 5 shows
This figure shows a case where excess air coming out of the raw water tank 1 or the aeration tank 20 is used as diffused air from the lower part of the contact oxidation tank 40, and the raw water tank 1 and the aeration tank 20 are omitted.

In the figure, reference numeral 5 indicates piping, and this piping 50 is connected to one or both of the bypass pipe 7 of the raw water tank 1 (Fig. 1) or the bypass pipe 27 of the explosive tank 20 (Fig. 2). In the contact oxidation tank 40, it is connected to an aeration part 51 provided slightly above the draining part 44. The surplus air is released from this air diffuser 51 into the waste water 43 in the pot,
Oxygen in the air is absorbed into the waste water 43 inside the pot. Reference numeral 52 indicates a pH meter for wastewater in the tank, and 53 indicates dissolved oxygen (
54 is a flow rate meter that detects the flow rate of wastewater flowing through the filling material in the same tank,
The output signals of these pH meter 52, Do meter 53, and flow rate meter 54 are connected to a control circuit 55.
This control circuit 55 detects the values detected by the pH meter 52, the Do meter 53, and the flow rate make 54, and based on the detected values, sends a command to the pump 45 to rotate the motor of the pump 45. Let the speed be adjusted. Therefore, surplus air released from one or both of the raw water tank 1 and the aeration tank 20 is introduced into the air diffuser 51 installed at the lower part of the filler 41 via the piping 50, and becomes bubbles to form waste water in the tank. 43
supply oxygen inside. As a result, the pH value, Do value, etc. of the waste water 43 in the pot fluctuate. These fluctuations are detected by the pH meter 52, Do meter 53, and flow rate meter 54, and the pH meter 52 and Do meter 53 detect the fluctuation values.
, the flow rate meter 54 supplies a detection signal to the control circuit 55. The control circuit 55 supplied with the detection signal sends a command to the pump 45 to change the rotational speed of the pump's motor. Accordingly, the power consumption of the pump 45 is reduced, and as a result, the entire processing device can save energy. Next, as shown in FIG.
This figure shows the case where it is introduced and used in the circulation piping 46 of , and the raw water tank 1 and the aeration tank 20 are omitted.

Further, the same reference numerals as in FIG. 5 indicate the same constituent elements, and the explanation thereof will be omitted. In the figure, the number 6 is the piping up to the river, and this piping 6
The engine is connected to one or both of the bypass pipe 7 of the raw water tank 1 (Fig. 1) or the bypass pipe 27 of the aeration tank 20 (Fig. 2), and is provided in the middle of the circulation pipe 46. Connected to Yu-61. This injector 6
1, the surplus air is released into the circulating tank waste water 43, and oxygen in the air is absorbed into the tank waste water 43. Even with this configuration, the surplus air as described above is transferred to the contact oxidation tank 4.
When using as diffused air from the bottom of 0 (Figure 5)
You can obtain the same action and effect as. In the above embodiment, a pH meter 52, a Do meter 53, and a flow rate meter 54 are all installed and used; All you have to do is combine them.

For example, when using the contact oxidation tank 40 for secondary treatment,
Due to the oxidative decomposition of organic matter, more Do in the tank is consumed than in the tertiary treatment, but if too much oxygen is supplied, the nitrification reaction progresses too much and the pH decreases. Therefore, in this case, it is better to use one or both of Do and pH as the main control factors.Also, when used in tertiary treatment, although the consumption of Do in the tank is not as large, the nitrification of ammonia nitrogen If the circulating flow rate is too high, the biofilm attached to the surface of the filler material may easily peel off, which can cause problems such as pH and/or flow rate being the main controlling factor. As explained above, the wastewater treatment method according to the present invention uses one or both of the surplus air coming out of the raw water tank or the aeration tank as diffused air from the lower part of the filler of the contact oxidation tank. A Do meter that dissolves oxygen in the wastewater in the tank by introducing air into an injector installed in the middle of the circulation piping of the contact oxidation tank, and detects dissolved oxygen (Do) in the contact oxidation tank;
A pH meter that detects the same pH and a flow rate meter that detects the flow rate of the filling material in the tank, or a combination of these two or more are installed in the tank, and
A control circuit is provided to detect the value detected by an o-meter, etc.
The structure controls the amount of circulating flow Z by sending commands from this control circuit to the pump and adjusting the rotational speed of the pump's electric motor, so either or both of the surplus air released from the raw water tank or the aeration tank can be effectively used. can be used,
This reduces the power consumption of the contact oxidation tank pump,
It has the excellent advantage of being able to achieve comprehensive energy savings.

[Brief explanation of the drawing]

Figures 1 to 3 show conventional organic wastewater treatment equipment. Figure 1 is an explanatory diagram of the raw water tank, Figure 2 is an explanatory diagram of the aeration tank, and Figure 3 is an illustration of the contact oxidation tank. An explanatory diagram, Figure 4 is a diagram showing changes over time in BOD, water volume, and sludge volume of inflow raw water, Figures 5 and 6 show examples of the present invention, and Figure 5 shows a raw water tank or an aeration tank. An explanatory diagram showing a case where the surplus air coming out of the contact oxidation tank is used as diffused air from the lower part of the contact oxidation tank. Figure 6 shows a case where the surplus air is introduced into the circulation piping of the contact oxidation tank and used. It is a diagram. 1... Raw water tank, 20... Aeration tank, 40...
...Contact oxidation tank, 41...Filling material, 45...
・Pump, 51... Diffuser, 52...
pH meter, 53...Do meter, 54...
...Flow velocity meter, 55...Control circuit, 61...
...Injector. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6

Claims (1)

[Scope of Claims] 1. A wastewater treatment method in which a raw water tank, an aeration tank, and a pump circulation type contact oxidation tank, which are devices for treating organic wastewater by a biological treatment method, are combined and connected to treat wastewater. One or both of the surplus air released from the water tank or the aeration tank is introduced into the wastewater of the contact oxidation tank, and a Do meter detects dissolved oxygen (DO) in the contact oxidation tank, and a pH meter detects the pH of the same. and one or more of these flow rate meters for detecting the flow rate of the filling material in the tank, and the above-mentioned Do
A control circuit is provided to detect the value detected by a meter, etc., and a command from this control circuit is sent to the pump's motor to adjust the rotational speed of the pump's motor, thereby controlling the circulating flow rate and saving energy. A wastewater treatment method characterized by: 2. Claim 1, characterized in that one or both of the surplus air released from the raw water tank or the aeration tank is guided into the wastewater through an aeration section installed under the filler of the contact oxidation tank. Wastewater treatment method described. 3. The wastewater according to claim 1, characterized in that one or both of the surplus air released from the raw water tank or the aeration tank is introduced into the wastewater through an injector installed in the circulation piping of the contact oxidation tank. Processing method.