JPH0127998B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of operating an aeration tank that is used for treating livestock human waste and is equipped with a cutter that is rotatably driven in a space above the liquid level and a water spray type defoamer.

Conventionally, it has been widely practiced to install an aeration device in a sewage treatment pit and blow oxygen from the air into the sewage to purify the sewage.

By the way, conventionally, when sewage with a high concentration, such as sewage consisting only of cow and pig excrement or human waste, is treated using an aeration device, the air introduced bubbles when it floats to the surface, creating a layer of bubbles on the surface of the sewage. If the sewage treatment tank is a closed type, the upper space will be filled with foam, and if the sewage treatment tank is an open type, the foam will overflow to the ground, making it more difficult for hygiene and maintenance inspection. This may lead to undesirable results.

Bubbles make it impossible to inspect the sewage treatment tank, and removing the bubbles is not easy. Although the above is an example, bubbles may generally be generated when wastewater is aerated or stirred.

However, foam is useful for keeping the liquid to be treated in the aeration tank warm, and on the other hand, when bacteria enter the endogenous respiration phase due to aeration, the amount of gas generated in the liquid to be treated increases, and it is necessary to release the gas. Since bubbles will appear, it is necessary to remove the bubbles and allow the gas to escape.

The defoaming device in the aeration tank devised in Utility Application No. 56-153449 is ``a closed upper wall of the aeration tank equipped with an aeration device that blows air into the tank that collects sewage and a covering inside the aeration tank. This is a foam defoaming device in an aeration tank that is equipped with a foam cutter that is rotated between the surface of the treated liquid and a water sprinkler type defoamer. This has the effect of helping to raise the temperature of the liquid to be treated and shortening the number of days required for fermentation.

However, in the above-mentioned device, a bubble detector is installed at the top of the aeration tank, and the condition of the bubbles is determined by the bubble detector, and the bubble cutter and defoamer are operated. Although there is a relationship between the amount of foam generated and the process of composting and fermentation in human waste treatment, the amount of foam generated and the amount of oxygen required do not show a close correspondence. In addition, there are variations in the generation of bubbles, and although it is excellent to have a bubble detector for control, there are limits to the detection and control of the composting process using a bubble detector. Therefore, in the above-mentioned device, the operation of the aeration device is manually controlled.

As described above, the present invention is an aeration tank equipped with an aeration device, a foam cutter equipped with a foam cutter, and a spray defoamer in the human waste treatment, and the present invention provides an appropriate method adapted to the composting process of the human waste treatment using the aeration device. driving and
The object of the present invention is to provide a method for operating an aeration tank equipped with an antifoaming device that can appropriately operate the antifoaming device so as to appropriately utilize foam generated from human waste for heat retention and dissipate gas.

The first invention of the present invention is a method of operating an aeration tank equipped with a foam cutter, a liquid defoamer, and an aeration device, and when human waste is placed in the aeration tank and aeration is performed by the aeration device, The aeration tank is equipped with a temperature sensor that detects the temperature of human waste, and the signal generated when the temperature sensor detects the temperature of the human waste is sent via a control device to a temperature close to the point at which the initial bacteria in the composting process begin to grow sufficiently. This is a method of operating an aeration tank equipped with an antifoaming device, characterized in that the aeration device is continuously operated until the antifoaming device is reached.

The second invention of the present invention is a method of operating an aeration tank equipped with a foam cutter, a liquid defoamer, and an aeration device, and when human waste is placed in the aeration tank and aeration is performed by the aeration device, The aeration tank is equipped with an acidity detector that detects the pH value of human waste, and the signal generated when the acidity detector detects the pH value of human waste is sent via a control device to ensure that the initial bacteria in the composting process are sufficiently grown. This is a method of operating an aeration tank equipped with an antifoaming device, characterized in that the aeration device is continuously operated until the temperature reaches a temperature close to the starting temperature.

FIG. 1 is a flow sheet showing an embodiment of the present invention. At the bottom of the aeration tank 1, an aeration device, generally indicated by 2, and a submersible motor pump, generally indicated by 3, are installed.

The aeration device 2 includes a motor 4 at the top and a pump 5 below. A nozzle body 7 is connected to the discharge port of the pump 5, and a diff user 8 is connected to the nozzle body 7 in a straight line.
The nozzle body 7 is provided with a nozzle (not shown), and is connected to a straight air introduction pipe 9 for introducing air that opens in an air chamber near the opening of the nozzle, and the air introduction pipe 9 is connected to an aeration tank. 1, and the other end of the air introduction pipe 9 is connected to the outlet passage of the outer cylinder 11 of the bubble cutter.

The foam cutter 10 includes a motor 12 in an outer cylinder 11 with a gap between the outer cylinder 11 and the outer cylinder 11. The outer cylinder 11 and the motor 12 are fixed to a base 13 fixed to the outside of the upper wall. The motor shaft passes through the base 13, and a foam cutter 14 is provided at the end of the shaft with a foam cutter blade located away from the liquid level in the aeration tank 1.
is fixed. The upper part of the outer cylinder 11 communicates with the atmosphere from a hole in the outer cylinder 11 via a muffler 15.

The submersible motor pump 3 has a pump 17 connected to the lower part of a motor 16 like a normal submersible motor pump, and a discharge pipe 18 is connected to the discharge port of the pump 17, and the discharge pipe 18 is inserted through the upper wall and connected to a T-joint 19. On-off valves 20 and 21 are fixed to both sides of the T-joint 19. A downward outlet pipe 22 connected to an elbow is fixed to the on-off valve 20, and a defoamer 23 is fixed to the end of the outlet pipe 22. The defoamer 23 is equipped with an umbrella-shaped liquid scattering plate spaced apart from the open end of the outlet pipe 22, and the liquid ejected from the outlet pipe 22 hits the liquid scattering plate and spreads the liquid over a wide liquid surface in the aeration tank 1. It is used to defoam by spraying.

A detector 24 is attached to the upper wall and measures the temperature or pH of the liquid in the aeration tank 1.
It is now possible to detect

That is, the detector 24 is a temperature detector or an acidity detector.

The on-off valve 21 is connected to a pipe 25 to a secondary storage tank for the next process or a pipe joint for connection to a tank car for transferring composted manure to a tank car.

The foam cutter 10 is a device based on Utility Model Application No. 56-79472, which is suitable for effectively utilizing the heat generated by the motor 12, but is not limited thereto. Reference numeral 26 denotes a liquid supply pipe through which a primarily treated liquid of cow and pig excreta is sent to the aeration tank 1. The detector 24 is wired to a control device 27 such as a microcomputer. The control device 27 discriminates the signal sent from the detector 24 and issues commands to control the aeration device 2, submersible motor pump 3, and bubble cutter 10. The control signal according to the command is sent to the amplifier circuit 28 and amplified. The amplifier circuit 28 is configured to open and close the output circuit 29. The output circuit 29 supplies electric power to the motor 4 of the aeration device 2, the motor 16 of the submersible motor pump 3, and the motor 12 of the bubble cutter 10, respectively.

In Figure 2, the horizontal axis shows the number of days that have passed since the human waste liquid (hereinafter sometimes simply referred to as liquid 30) was added to the aeration tank 1, and the vertical axis shows the temperature and pH of liquid 30, and the aeration tank. FIG. 1 is a diagram showing the temperature around No. 1. FIG.

As shown in Fig. 2, the temperature of the liquid 30 filled into the aeration tank 1 from the liquid pipe 26 is as low as 21°C, which is almost equal to or slightly higher than the air temperature, and the preparation time for the bacteria in the liquid 30 to capture organic matter. temperature required for sufficient bacterial growth.
The initial temperature of the liquid 30 is therefore lower in winter. Therefore, a command from the control device 27 is sent to the motors 4 and 12 via the amplifier circuit 28 and the output circuit 29, the aeration device 2 is operated, and the motor 12 rotates the cutter 14. The air required for aeration is silenced by silencer 1.
5-outer cylinder 11-air introduction pipe 9-nozzle body 7, and is drawn into the liquid discharged by the pump 5 in the diffuser 8 and dispersed into the liquid 30.
Part of the oxygen in the air that has entered the liquid 30 dissolves into the liquid, but the rest rises to the top of the liquid 30 in the form of bubbles. Since the liquid 30 is highly concentrated human waste, the bubbles do not disappear and form a foam layer on the liquid surface. The aeration air cools the motor 12 in the barrel 11 and the air is warmed. Therefore, due to the air having a higher temperature than the liquid temperature, the liquid temperature initially becomes 30.
is heated. From the beginning until the liquid temperature reaches about 20 to 30°C, the temperature of the liquid 30 increases due to fluid friction caused by agitation due to aeration in order to prepare conditions for bacterial growth. Thus, as shown in Figure 2 as an example, when the temperature reaches around 30°C, bacterial growth rapidly increases. However, even when bacteria rapidly increase, the total amount of oxygen required is not large, so if the aeration device 2 is operated as it is, the amount of oxygen required will be the same as in the latter half of the stage when bacteria undergo endogenous respiration. Since it is set to meet the maximum oxygen demand, it causes overaeration and kills bacteria. Therefore, when the detector 24 detects a liquid temperature of 30°C, the signal is sent to the control device 27, which issues a command to operate the motor 4 intermittently.
9, the motor 4 enters intermittent operation, for example, running for 2 hours and stopping for 1 hour, and the amount of oxygen supplied is limited so that an appropriate amount of oxygen is given to the bacteria.

On the other hand, since the foam cutter 10 remained in operation, the foam generated is liquefied by the cutter 14 of the foam cutter 10. Since the defoaming effect of the cutter is limited to the area near where the cutter rotates, the cutter 1 is lower than the liquid level of the liquid 30.
4 is far apart, so the foam layer remains on the liquid surface.
Therefore, the bubble remover 10 is operated until the liquid temperature has risen sufficiently and the amount of gas generated from the liquid 30 is not large. In other words, the liquid temperature is 20 to 30℃, and in the example shown in Figure 2, it is approximately
The bubble cutter 10 is operated continuously up to 30°C.

Thus, at the same time as the motor 4 enters intermittent operation, or when the temperature of the liquid 30 rises further and the liquid temperature reaches 40 to 50°C, the amount of bacteria becomes the largest and the generation of bubbles increases, the detector 24 detects that the liquid temperature is about 40°C. A set value of .degree. C. to about 50.degree. C. is detected and the signal is sent to the control device 27. The control device 27 de-energizes the motor 12 of the bubble cutter 10, issues an energization command to the motor 16 of the submersible motor pump 3, de-energizes the motor 12 via the amplifier circuit 28 and output circuit 29, and de-energizes the motor 16. The pump 17 sucks in the liquid 30 and sends it out through the discharge pipe 18 through the T-joint 19, the previously opened on-off valve 20, and the outlet pipe 22, and is sprayed with water by the defoamer 23 to form the liquid 30. Disappear the bubbles on top.
The liquid spray type defoamer 23 completely extinguishes foam within the liquid spray range. At this point, the liquid 30 is in the process of reaching its maximum amount of bacteria, and the heat of fermentation is also increasing, so there is no need to keep it warm, and the amount of gas containing steam generated from the liquid 30 is increasing, so it is necessary to dissipate it. comes out. The temperature of liquid 30 further increases to 40
When the temperature reaches ~50°C and bacteria begin to breathe naturally, the amount of oxygen required also reaches its maximum.When the detector 24 detects a temperature between 40 and 50°C, the signal is sent to the control device 27. control device 2
7, the motor 4 is switched to continuous operation via the amplifier circuit 28 and the output circuit 29, and aeration is performed continuously. Alternatively, depending on the state of the liquid 30, the amount of organic matter also decreases at this stage, so the aeration device 2 may continue to be operated intermittently. When the temperature of the liquid reaches about 50℃, the temperature will rise due to fermentation heat alone, so you can just take in the atmosphere. In this state, the aeration tank is operated and a large amount of gas containing steam is generated above the liquid level. On the other hand, although many bubbles are generated, they are eliminated by the defoamer 23, so that gas dissipation is not hindered. Surface aeration is also performed by water sprinkling. In addition, since the defoaming effect of the water sprinkler type defoamer is so remarkable that no foam is left on the liquid surface, such defoaming may not be necessary depending on the liquid 30, so the motor 12 and 16 are operated alternately to moderate the generation of foam and to reduce power costs.

When ripening is completed in this way, the motors 4, 12, 1
6 is cut off, the on-off valve 20 is closed and the on-off valve 21 is opened, and the liquid 30 is pumped out by the pump 17 to the pipe 2.
Sent from 5.

If the detector is to detect the PH of the liquid 30, the liquid temperature and PH are related, so the PH that corresponds to the temperature
The control is similar to that described above. As shown in Figure 2, the temperature corresponded to approximately 30℃.
Since the pH is in the initial saturated state at 8.0, the aeration device 2 is switched to intermittent operation when the pH is slightly lower than 8.0. For example, the pH corresponding to a temperature of 42℃ between 40 and 50℃ is 8.2.
is stopped and the liquid is sent to the defoamer 23. The pH corresponding to a temperature of about 45° C. is 8.4, but it is in a saturated state, so the aeration device 2 is switched to continuous operation at around PH8.4, which is lower than PH8.4. Alternatively, continue intermittent operation when the amount of organic matter is decreasing.

As described above, according to the method of operating an aeration tank equipped with a foam cutter, a liquid defoamer, and an aeration device according to the present invention, during the preparatory period for bacterial growth, the action of the foam cutter allows the foam to be properly liquefied. The aeration equipment remaining on the surface is operated continuously and the temperature rises. Additionally, the input to the foam cutter motor is transferred as heat into the aeration tank. When the bacteria enters the growth phase, it is necessary to operate intermittently to prevent overaeration and at the same time measure the temperature rise, so the foam cutter is operated and the foam is left behind. When the amount of bacteria approaches the maximum amount, the bubble cutter is stopped and either a water spray type defoamer is used to extinguish the bubbles on the liquid surface, or the bubble cutter and defoamer are operated alternately to eliminate the gas in the liquid. Make it easier to escape. At this time, the temperature of the liquid is maintained by the fermentation heat, so there is no need to keep it warm. Then, when the liquid temperature reaches about 40 to 50°C, the amount of oxygen required is the highest, so continuous aeration is carried out, or depending on the amount of organic matter remaining, intermittent aeration is continued. This process is carried out automatically, and the aeration treatment of livestock human waste is carried out in an optimal manner.

[Brief explanation of drawings]

FIG. 1 is a flow sheet explaining an embodiment of the present invention, and FIG. 2 is a diagram showing the relationship between the number of days elapsed after composting and the condition of human urine in FIG. 1. 1... Aeration tank, 2... Aeration device, 3... Submersible motor pump, 4... Motor, 5... Pump, 7...
... Nozzle body, 8 ... Diffusion user, 9 ... Air introduction pipe, 10 ... Bubble cutter, 11 ... Outer cylinder, 12
... Motor, 13 ... Base, 14 ... Foam cutter, 15 ... Silencer, 16 ... Motor, 17 ...
...Pump, 18...Discharge pipe, 19...T joint, 2
0... On-off valve, 21... On-off valve, 22... Outlet pipe, 23... Defoamer, 24... Detector, 25...
Piping, 26...Liquid feeding pipe, 27...Control device, 28
...Amplification circuit, 29...Output circuit, 30...Liquid.

Claims (1)

[Claims] 1. A method for operating an aeration tank equipped with a foam cutter, a liquid defoamer, and an aeration device, in which human waste is placed in the aeration tank and aeration is performed by the aeration device. The tank is equipped with a temperature sensor that detects the temperature of the human waste, and a signal generated when the temperature sensor detects the temperature of the human waste is sent via a control device to reach a temperature close to the point at which the initial bacteria in the composting process begin to sufficiently proliferate. A method for operating an aeration tank equipped with an antifoaming device, characterized by continuously operating the aeration device until 2. A method of operating an aeration tank equipped with a foam cutter, a liquid defoamer, and an aeration device, and when human waste is placed in the aeration tank and aeration is performed by the aeration device, the PH of the human waste in the aeration tank is Equipped with an acidity detector that detects the pH value of human waste, the acidity detector detects the pH value of human waste and generates a signal that is used to control the aeration until the temperature reaches a temperature close to the point at which the initial bacteria in the composting process begin to grow sufficiently. A method of operating an aeration tank equipped with an antifoaming device, characterized in that the device is operated continuously.