JP2007152268A - Sludge reducing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a system for efficiently reducing excess sludge produced in the treatment of organic sewage. <P>SOLUTION: In the sludge reducing device, a cavitation generation device is disposed in the middle of a pipe extended from a sedimentation tank to an aerobic biological treatment tank and a solubilization device for solubilizing excess sludge by cavitation generated in the cavitation generation device is disposed, wherein the cavitation generation device is composed of: a transfer pressure pump; a funnel type shock wave generating pipe which becomes thicker on the downstream side; a pipe for crushing microorganism connected to the shock wave generating pipe; and a low pressure generation facilitating plate disposed between the shock wave generating pipe and the pipe for crushing microorganism. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a sludge reduction treatment apparatus for reducing excess sludge generated in the treatment of organic sewage and a sewage treatment system including the sludge reduction treatment apparatus.

  FIG. 4 is a structural diagram of microbial cells. The cell membrane is a membranous structure that surrounds the outside of the microbial cell, and forms a cytoplasmic membrane, cell wall, mucus layer, or capsule from the inside. The cell wall is a hard membrane outside the cytoplasm. The life phenomenon proceeds safely while being protected by various layers of various films. The conventional sludge treatment treats sludge cells in a complete state wrapped in a strong cell membrane, whether living sludge cells or dying sludge cells. With this, dehydration and biological treatment must be completed incompletely. If the cell membrane is destroyed here, the water in the cell can be easily dehydrated. Not only that, but the cytoplasm is also exposed to the outside, so it is of course subject to processing. The cytoplasm in FIG. 4 is a complex colloidal system wrapped in a cell membrane. The cytoplasm contains granules that are closely related to metabolism such as ribosomes and granules such as polysaccharides and lipids that are storage substances. If these nutrients break through the cell membrane and jump out, they can be used as substrates for other microorganisms, so new biological treatment can be expected. Sludge cell membrane destruction, this process is the starting point for a new biological treatment, that is, an innovative process of biodegradation → dissipation → elimination of sludge components. That is, the biological treatment process of sewage is a process in which microorganisms ingest organic substances and inorganic substances in sewage as a substrate while decomposing organic substances and inorganic substances, and the microbial mass (floc) is sludge. The final biological treatment is the sludge dewatering process and the next sludge cake manufacturing process. Although dehydrated, the water content of the dewatered cake is as high as 80%. No matter how good the dehydrator, the water content is about 70% at most. This is because a lot of moisture remains in the cells only after the extracellular moisture has been dehydrated. So far, as a method for treating this surplus sludge, generally, after dehydration, landfill, ocean dumping, incineration and the like have been performed. However, since these methods require a large amount of expenses and facilities, a proposal for a new surplus sludge treatment method has been required.

As an excess sludge treatment method that meets this requirement, an ozone treatment method, a high-temperature microorganism treatment method, a mechanical treatment method, a cavitation treatment method, and the like have been proposed so far. One of the cavitation processing methods among them is disclosed in Patent Document 1. The treatment method disclosed in this article is a solubilization treatment tank for sludge generated in an aerobic biological treatment tank and a nozzle disposed so that an injection port faces the solubilization treatment tank. And a pressurizing pump that pressurizes the sludge and supplies it to the nozzle, and injects the sludge into the solubilization treatment tank from the nozzle injection port to solubilize the sludge by cavitation. A part of the sludge is solubilized by the solubilization device to enhance biodegradability. Then, by returning this sludge to the aerobic biological treatment tank again, the excess sludge can be greatly reduced.

Specifically, a solubilization tank is installed in the middle of a pipe extending from the sedimentation tank to the aerobic biological treatment tank, and cavitation (local and rapid pressure drop of the liquid) is performed by the nozzle in the solubilization tank. The excess sludge is solubilized by this. In other words, the nozzle disposed so that the injection port faces the solubilization tank and the sludge are pressurized and supplied to the nozzle, and the sludge is injected into the solubilization tank from the nozzle injection port. Then, cavitation is generated, so that the microbial cells constituting the excess sludge are destroyed and solubilization occurs.
JP 2003-10890 A

However, in order to sufficiently destroy microbial cells in the treatment method disclosed in the above publication, a solubilization treatment tank is provided, and cavitation is generated by the nozzle in the solubilization treatment tank. Could not be avoided.

In addition, the pressure of the pressure pump used in the solubilization processing apparatus is set to 3 MPa or more, and there is a problem with the energy saving effect, and it becomes a large equipment cost burden, so it becomes a limited market. Yes.

This invention is made | formed in view of this point, The place made into the objective is to avoid the enlargement of the whole apparatus, and to make it possible to solubilize sludge reliably by a cavitation effect.

  In order to achieve the above object, according to the first aspect of the present invention, a cavitation generator is provided in the middle of a pipe extending the sludge generated in the aerobic biological treatment tank from the sedimentation tank to the aerobic biological treatment tank. In the sludge reduction processing apparatus provided with a solubilization device for surplus sludge by cavitation generated in the device, the cavitation generation device is used for crushing microorganisms connected to a transfer pressure pump, a shock wave generation pipe, and a shock wave generation pipe By comprising the piping and the low-pressure generation promoting plate disposed between the shock wave generating piping and the microorganism crushing piping, sludge can be effectively reduced.

  Further, according to the invention of claim 2, since the transfer pressurizing pump is a hose pump, sludge is easily transferred to attract fluid by generating a vacuum by elastic recovery force when the shoe is separated from the hose. It was possible to press.

  Furthermore, according to the invention described in claim 3, since the cavitation diameter to be generated is approximately the same as that of microbial cells, the microbial cells can be surely destroyed, and sludge can be reduced more efficiently. did.

  According to the present invention, the sludge is pressurized to a predetermined pressure by the transfer pressurization pump, and when the water flow passes through the funnel portion, it changes to a jet water flow, and cavitation due to low-temperature boiling occurs due to the water flow. Microbial cells constituting sludge are destroyed and solubilized by the combined action of the energy when this cavitation bursts and the impact that hits the collision plate. In addition, the microorganism crushing pipe creates a stronger shock wave and effectively destroys the microbial cell membrane. At the same time, a relatively medium pressure pump can be used, and the apparatus itself can be miniaturized.

Specifically, a hose pump is employed as the transfer pressure pump. As a result, the sludge can be brought into the medium pressure range (0.3 Mpa to 1.0 Mpa) relatively easily, which is practical.

Further, by setting the cavitation diameter to be generated to be approximately the same as that of the microbial cell, it is possible to reliably destroy the microbial cell when the cavitation is ruptured, and it is possible to efficiently solubilize.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing a schematic configuration of a sludge reduction treatment apparatus. As shown in this figure, the sludge reduction treatment apparatus treats organic sewage 9 in the aerobic biological treatment tank 1 from the upstream side to the downstream side in the sludge flow direction, and solid-liquid separation in the sedimentation tank 2. Then, it is treated in a wastewater treatment process to obtain treated water 10 and return sludge 11, introduced into the solubilizer 3 as return sludge 11, solubilized and decomposed return sludge, and then biological treatment in the wastewater treatment process It returns to the tank 1 and performs biodegradation of soluble organic matter and sludge.

The return sludge 11 introduced into the solubilizer 3 is guided into the shock wave generating pipe 5 by the hose pump 4 as a transfer pressurizing pump, the return sludge 11 is accelerated, and then the pipe 5 is expanded to lower the pipe internal pressure. Causes cavitation. Further, the efficiency is further improved by arranging the low pressure generation promoting plate 6 immediately after the shock wave generating pipe 5. The low-pressure generation promoting plate 6 can make a fine and uniform bubbling flow, whereby the microorganisms can be effectively crushed and the solubilization treatment can be performed efficiently. In addition, when the collision plate 7 is provided as shown in FIG. 3, the microorganisms can be crushed by causing the generated cavitation to collide with the collision plate 7.

A filter may be provided as a pretreatment on the suction side of the transfer pressurization pump 4, and in that case, relatively insoluble materials such as relatively large dust and hair in the sludge can be removed. In addition, it is preferable that the suction side of the transfer pressurization pump 4 is sucked from the layer region of the sedimentation tank 2 because the sediment in the bottom layer is not sucked.

Further, a heating device may be provided as a pretreatment on the suction side of the transfer pressurization pump 4, and in that case, a decrease in the strength of the cell membrane of the microbial cells constituting the sludge is promoted with heating, and the solubilizer The microbial cells can be easily destroyed by cavitation at this point, or the sludge pressure increases by heating the sludge, leading to a reduction in the load on the transfer pressurization pump. Specifically, an electric heater is used for the piping as the heating means.

A detailed configuration of the solubilizer 3 is shown in FIG. The shock wave generating pipe 5 has two funnels 5a and 5b facing each other, and a low pressure generation promoting plate 6 is provided at the outlet. The return sludge 11 is accelerated at the inlet-side funnel 5a and the pipe diameter is abruptly widened at the outlet-side funnel 5b, so that the pressure in the pipe can be reduced. As a result, fine cavitation can be generated. For this reason, the flow mode of the gas-liquid two-phase flow between the cavitation and the return sludge 11 is a uniformly dispersed bubble flow. When this bubbly flow passes through the microorganism crushing pipe 8, cavitation and microorganisms such as rotifer and weasel insect come into contact with each other to crush the microorganisms. Thereby, microbial cells are refined and solubilized. Note that the microorganism crushing pipe 8 is configured as a double pipe so as to prevent the return sludge 11 from flowing out even if a hole is formed in the pipe due to wear due to cavitation.

If there is no low pressure generation promotion plate 6, the diameter of the cavitation becomes large, and the flow mode of the gas-liquid two-phase flow between the cavitation and the return sludge 11 is slag flow, floss flow or annular spray. End up. For this reason, the contact opportunity between the generated cavitation and the microorganism is reduced, and the microorganism cannot be sufficiently crushed.

The diameter of the narrow opening 6a of the low pressure generation promoting plate 6 is preferably about 1/6 to 1/2 of the diameter of the outlet funnel 5b. If it is too thin, the return sludge 11 is likely to be clogged, and if it is too thick, the diameter of the cavitation is large. As a result, the bubble flow cannot be obtained, and the opportunity for contact with the microorganisms is reduced, so that the microorganisms are not sufficiently crushed.

Further, the distance between the low pressure generation promoting plate 6 and the collision plate 7 is preferably about 1/2 to 2 of the diameter of the narrow mouth portion 6a. If the distance is too close, the return sludge 7 is likely to be clogged, and if too long, the cavitation disappears. Amplification piping is required for a long time, and the entire apparatus becomes large. In the present invention, the contact time between the cavitation and the microorganisms is lengthened, the fine liquid cavitation is generated, the gas-liquid two-layer flow with the returned sludge is made into a bubble flow state, and the contact opportunity is increased, thereby effectively preventing the destruction of the microbial cell membrane. The main purpose is to make it change, and changes can be made without departing from the spirit.

For example, a pressure sensor may be provided as a safety device in a pipe (for example, between the pump 4 and the shock wave generating pipe 5), and the pump 4 may be stopped when an abnormal pressure is detected by the pressure sensor. it can. In addition, by providing a flow sensor (for example, in the vicinity of the pressure sensor) and a throttle valve (for example, between the pump 4 and the shock wave generating pipe 5 and upstream of the flow sensor) in the pipe, the flow rate and flow velocity flowing into the shock wave generating pipe 5 Can be controlled optimally. In addition, a timer can be provided so that periodic maintenance can be promoted by stopping the pump at the maintenance time and turning on an indicator lamp or the like.

The experimental results conducted to confirm the sludge solubilization treatment according to this embodiment will be described below. In this experimental example, after adjusting to the optimum pressure of the pressure pump (0.9 Mpa), the sludge that passed through the solubilization apparatus 3 once or five times and the sludge that did not pass through were each centrifuged, and then soluble in clean water. COD (chemical oxygen demand) was measured. This solubility COD shows that solubilization of sludge progresses, so that the value is high. Table 1 shows the experimental results.

It is the table | surface which compared the soluble COD with respect to the water of sludge.

From these experimental results, it was confirmed that the solubilization processor 5 of this embodiment can surely solubilize sludge. In addition, the excess sludge was not pulled out and the MLSS concentration in the aeration tank was not increased, and the sludge reduction rate was 82% compared with that before the introduction of this apparatus, confirming that the sludge reduction was promoted.

As described above, according to the present invention, it can be used for sewage, rural village drainage, various organic wastewater treatment facilities, and the like.

It is the block diagram which showed schematic structure of the sludge reduction processing apparatus. It is sectional drawing which showed the outline of the solubilization processing apparatus. It is sectional drawing which showed the outline of another Example of the solubilization processing apparatus. It is a structural diagram of microbial cells

Explanation of symbols

1, aerobic biological treatment tank 2, sedimentation tank 3, solubilizer 4, transfer pressurization pump 5, shock wave generation pipe 6, low pressure generation promotion plate 6a, narrow mouth portion 7, collision plate 8, pipe for microorganism crushing

Claims (3)

A cavitation generator is installed in the middle of the pipe that extends sludge generated in the aerobic biological treatment tank from the sedimentation tank to the aerobic biological treatment tank, and a solubilizer is provided to solubilize excess sludge by cavitation generated in the cavitation generator. In the sludge reduction processing apparatus, the cavitation generator is disposed between the transfer pressurization pump, the shock wave generating pipe, the microorganism crushing pipe connected to the shock wave generating pipe, and the shock wave generating pipe and the microorganism crushing pipe. Sludge reduction treatment device characterized by comprising a low pressure generation promotion plate 2. The sludge reduction processing apparatus according to claim 1, wherein the transfer pressure pump is a hose pump. 3. The sludge reduction treatment apparatus according to claim 1 or 2, wherein the generated cavitation diameter is approximately the same as that of microbial cells.