JP5914930B2 - Biological treatment apparatus and biological treatment method - Google Patents

Description

  The present invention relates to a biological treatment apparatus and biological treatment method for treating a liquid to be treated by biological treatment.

  Conventionally, as a technique for treating waste, wastewater, sewage, sewage sludge, etc. in agriculture, livestock industry, fishery industry, etc., a method of biologically treating these with anaerobic microorganisms has been developed and put into practical use. In such conventionally used biological treatment apparatuses and methods, organic substances contained in wastes, wastewater, etc. are fermented by anaerobic microorganisms. And when fermenting organic matter with anaerobic microorganisms, methane, carbon dioxide, ammonia, hydrogen gas, etc. are finally generated, so in order to treat these gases, waste and wastewater are treated in parallel. The gas released into the gas phase is collected, and a specific gas such as methane gas is separated from the collected gas.

  In such biological treatment apparatus and method, chemical absorption method, physical absorption method, PSA (Pressure Swing Adsorption) can be used as a method for concentrating and separating methane gas by removing carbon dioxide from gas generated from waste or waste water. And separation methods using a separation membrane are known. Among these methods, it is known that a system can be easily configured and a device can be made relatively small by adopting a separation method using a separation membrane (for example, Patent Documents 1 and 2). .

JP 61-53994 A Japanese Patent Laid-Open No. 4-177013

In Patent Document 1, gas generated from a landfill site due to the action of anaerobic microorganisms and recovered in the gas phase is recovered, and methane gas is separated using a separation membrane through the gas into a separation membrane through which carbon dioxide easily passes. A method is described.
Further, Patent Document 2 collects a mixed gas of methane gas and carbon dioxide gas generated by wastewater treatment by anaerobic microorganisms and released into the gas phase, and further separates and uses the methane gas from the mixed gas using a separation membrane. The device to do is shown.

  However, in the biological treatment method and biological treatment apparatus, the gas generated by the anaerobic microorganisms is released into the gas phase and recovered, but the biological treatment method and biological treatment apparatus that have been used conventionally are used. However, the generated gas remains in the waste, waste water, and microbial aggregate (that is, biofilm) without being released into the gas phase, and there is a problem that the generated gas cannot be sufficiently recovered. For this reason, the gas recovery amount of the whole system in the biological treatment method or the biological treatment apparatus cannot be increased, and the energy recovery amount cannot be increased.

  Therefore, in the present invention, a biological treatment apparatus and a biological treatment method capable of increasing the amount of recovered gas by recovering a gas that has been consumed or remained in a processing object such as waste or wastewater. The purpose is to provide.

In order to solve the above-described problems, the present invention provides a biological treatment apparatus for treating a liquid to be treated by biological treatment, wherein the biological treatment tank generates a gas by biologically treating the liquid to be treated, and the biological treatment. A gas separation tank disposed downstream of the tank and receiving a liquid to be treated biologically treated in the biological treatment tank , wherein the gas separation tank is immersed in the liquid to be treated biologically treated in the biological treatment tank; A gas separation unit having a separation membrane for transmitting the generated gas, a gas separation tank having a decompression unit for decompressing the inside of the gas separation unit, and a gas for storing the gas discharged from the biological treatment tank and the gas separation tank A storage unit; and a control unit that controls the temperature of the liquid to be processed to a predetermined temperature. Reducing the pressure of the inside of the stage.

Further, the present invention is that the liquid to be treated body by biological treatment, the gas generated by the biological treatment, is separated from the treated liquid using a gas separation membrane which is immersed in the processing liquid which is biologically treated, separated A biological treatment method for recovering the gas, comprising a decompression means connected to the gas separation membrane, while driving the decompression means only when the liquid to be treated falls below a predetermined temperature. Perform gas separation.

  As described above, according to the present invention, the amount of gas recovered can be increased by recovering the gas that has been consumed or remained in the processing object such as waste or wastewater.

It is a block diagram of the biological treatment apparatus by embodiment of this invention.

  Hereinafter, a biological treatment apparatus and a biological treatment method according to an embodiment of the present invention will be described with reference to the drawings.

  As shown in FIG. 1, the biological treatment apparatus 1 includes a biological treatment tank 3 for biologically treating a liquid to be treated to generate gas, and a gas separation tank 5 for separating the gas generated in the biological treatment tank 3. And a decompression pump 7 for decompressing the inside of the gas separation tank 5 and a gas storage unit 9 for storing gas.

  The biological treatment tank 3 is a so-called UASB (Up-flow Anaerobic Sludge Blanket) reactor. If necessary, a holding carrier 11 holding microorganisms may be provided therein. A temperature control means (cooling means) 13 is provided for controlling the temperature of the fluid to be treated when the temperature of the fluid to be treated exceeds a certain temperature. In addition, the biological treatment tank 3 discharges the biological treatment tank inlet 15 through which the liquid to be treated flows into and the biological treatment liquid to be treated from the biological treatment tank 3 toward the gas separation tank 5. The biological treatment tank outlet 17 and a biological treatment tank gas discharge port 19 for discharging a part of the gas generated by the biological treatment toward the gas storage unit 9 are provided. And the biological treatment tank 3 ferments the to-be-processed liquid which flowed in from the biological treatment tank inlet 15 by the microorganisms currently hold | maintained in the biological treatment tank 3, A part of gas generated by the fermentation process is a biological treatment tank. The gas is discharged to the gas storage unit 9 through the gas discharge port 19. Further, the liquid to be treated in which a part of the gas generated by the fermentation process remains is discharged from the biological treatment tank outlet 17 toward the gas separation tank 5. In this embodiment, the microorganism is held on the holding carrier, but may be suspended in the tank by granulating it.

  As the holding carrier 11, a carrier provided with a microorganism carrying mechanism with high bioadhesiveness can be used. The holding carrier 11 is made of a porous material having a high specific surface area and / or a material to which microorganisms easily adhere, and is preferably made of foamed plastic or carbon fiber. Further, an organism such as an anaerobic microorganism may be attached to the holding carrier 11 in advance.

  As the cooling means 13, a heat exchanger, an air-cooled gas blower, or the like can be used. The installation position of such a cooling means is not limited to the inside of the biological treatment tank 3, but may be any position as long as the biological treatment tank 3 including the vicinity of the biological treatment tank inlet 15 can be efficiently cooled. Good.

  The gas separation tank 5 includes a gas separation tank inlet 21 connected to the biological treatment tank outlet 17, a gas separation means 23 for separating the gas from the liquid to be treated in which the gas is dissolved, and the gas is separated. And a gas separation tank outlet 25 for discharging the liquid to be treated from the gas separation tank 5. Moreover, it is preferable that the upper part of the gas separation tank 5 is sealed in order to prevent re-dissolution of the gas.

  The gas separation means 23 has a separation membrane that allows gas to pass therethrough. Examples of the gas separation means include known separation membrane modules (hollow fiber membrane modules, flat membrane modules, etc.), but they are hollow from the viewpoint that the inside can be easily decompressed, the membrane has a large specific surface area, and a high filling rate. It is preferable to use a thread membrane module. The hollow fiber membrane module includes a plurality of hollow fiber membranes 29 (separation membranes) and an air collection tube 31, and is fixed to the air collection tube 31 with at least one end of the hollow fiber membrane 29 communicating with the air collection tube 31. Yes. Similarly, the other end of the hollow fiber membrane 29 may be fixed in a state where it communicates with the air collecting tube 31, or the end may be sealed, or folded in a loop shape. Also good. Such a gas separation means 23 is, for example, in the gas separation tank 5 so as to be immersed in the processing object and not to obstruct the flow of the processing object, for example, substantially parallel to the longitudinal direction of the gas separation tank 5. Is arranged.

  Further, as the separation membrane, a non-permeable separation membrane is used because it is easy to separate and recover a gas not containing moisture even when biologically treating an object to be treated with a high moisture content. Preferably, a water-impermeable hollow fiber membrane is used. Examples of the non-permeable hollow fiber membrane include a separation membrane made of a hydrophobic material and a three-layer structure membrane in which a gas-permeable non-porous separation layer is sandwiched between porous support layers.

  Further, as the separation membrane, it is preferable to use a gas selective permeable separation membrane because it is easy to separate and recover a useful gas such as hydrogen, ammonia, methane, etc. at a high concentration. It is more preferable to use a thread membrane. Examples of the gas permselective hollow fiber membrane include a three-layer structure membrane having a non-porous separation layer made of polyurethane.

  As the hollow fiber membrane 29, a water-impermeable hollow fiber membrane is used because it is easy to separate and collect a gas that does not contain moisture even when biologically treating an object to be treated with a high moisture content. Are preferable, and the same as those mentioned in the biological treatment apparatus can be used.

  Moreover, as the hollow fiber membrane 29, it is preferable to use a gas permselective hollow fiber membrane from the viewpoint that it becomes easy to separate and recover useful gases such as hydrogen and methane at a high concentration. The same ones are listed.

  The decompression pump 7 is not particularly limited as long as it can exert a decompression action on the gas separation means 23. For example, the decompression pump 7 is constituted by a suction pump. The decompression pump 7 is connected to the air collecting pipe 31 of the gas separation means 23, and decompresses the inside of the hollow fiber membrane 29 to suck the gas separated from the liquid to be treated.

  The gas storage unit 9 is connected to the decompression pump 7, the biological treatment tank gas discharge port 19, and the gas separation tank gas discharge port 27, and collects and stores the gas flowing in from these. The gas storage unit 9 is not particularly limited as long as it can store the separated and recovered gas, and an aluminum bag, a pressure vessel, or the like can be used.

Next, a biological treatment method using the biological treatment apparatus described above will be described.
First, a processing object is put in the biological treatment tank 3, the processing object is biologically processed, and gas is generated. At the same time, the decompression pump 7 is operated to decompress the gas separation means 5 and permeate and separate the gas generated in the object to be treated. The gas discharged from the biological treatment tank gas outlet 19 and the decompression pump 7 in the upper part of the biological treatment tank 3 is collected in the gas storage unit 9.

  When the liquid temperature in the biological treatment tank 3 reaches a predetermined temperature, that is, the amount of gas generated in the gas phase exceeds the amount dissolved in the liquid to be treated, the cooling means 13 is operated to activate the biological treatment tank. By lowering the liquid temperature in 3, the gas can be recovered more suitably from the liquid to be treated. Since the amount of gas generated in the gas phase changes as appropriate depending on the type of gas, the concentration of organic substances in the liquid to be treated, and the activity of microorganisms, the temperature for determining whether or not to operate the cooling means 13 depends on the type of gas. It is set as appropriate according to the courage concentration of the liquid to be treated or the activity of the microorganism. Under actual use conditions, it is more preferable to change the temperature conditions as appropriate by monitoring the organic substance concentration and gas generation amount of the liquid to be treated. Moreover, it is preferable to use a microorganism having activity even under low temperature conditions so that biological treatment can be performed even under low temperature conditions. In this way, when the liquid temperature in the biological treatment tank 3 is high, the cooling means 13 is operated to lower the liquid temperature, thereby enabling operation under temperature conditions in which almost no gas is generated in the gas phase. Become. Thereby, remelting from the gas phase is substantially eliminated, and the generated gas can be recovered from the liquid using only the separation membrane. In particular, when gas is not recovered from the gas phase, the only means for recovering the gas is the separation membrane, which contributes to simplification of the apparatus. Even when the cooling means 13 is not provided, when the gas concentration in the liquid to be processed is low, recovery is performed only from the gas phase, and the gas concentration in the liquid to be processed is high (that is, the liquid temperature of the liquid to be processed is predetermined). It is preferable to operate the decompression pump 7 for decompressing the inside of the gas separation means 23 only when In this way, by operating the decompression pump 7 only when the liquid temperature falls below a predetermined temperature, it is possible to increase the recovery efficiency of the entire system while reducing the energy loss required for the decompression means of the separation membrane. .

  In the biological treatment apparatus 1 described above, the gas separation means is arranged in the gas separation tank so as to come into contact with the treatment object, so that the gas remaining in the treatment object can be recovered. Further, in the biological treatment method described above, the gas separation means is brought into contact with the treatment object, so that the gas remaining in the treatment object can be recovered.

  Furthermore, according to the biological treatment apparatus 1 described above, the efficiency can be improved by controlling the dissolution of the generated gas in the gas phase / liquid phase or switching the processing method in accordance with the dissolution of the generated gas in the gas phase / liquid phase. Biogas can be recovered. That is, since the biological treatment apparatus 1 is configured to be operable under temperature conditions in which almost no gas is generated in the gas phase, the gas can be prevented from being re-dissolved from the gas phase. The biogas remaining inside can be recovered later using a separation membrane. Thus, by separating the gas recovery process from the gas phase and the gas recovery process from the liquid phase, each process can be optimized, and as a result, an improvement in the total gas recovery rate is expected. it can. In addition, by performing the gas recovery process from the liquid phase after the gas recovery process in this way, the gas phase recovery can be performed in the preceding biological treatment tank, and the gas can be recovered from the liquid in the subsequent separation membrane tank. This enables efficient system design.

  Furthermore, by providing a control means for controlling the temperature of the liquid to be treated, it becomes possible to operate under low temperature conditions where almost no gas is generated in the gas phase. It is also possible to recover the evolved gas from When the gas is not recovered from the gas phase, a separation membrane is sufficient as a means for recovering the gas, so that the apparatus can be simplified.

  In addition, by operating the separation membrane only when the concentration of the generated gas in the liquid is high (that is, the liquid temperature of the liquid to be treated is low temperature or lower than the predetermined temperature), energy loss required for the decompression means of the separation membrane is reduced. Recovery efficiency can be increased.

  Further, by using a hollow fiber membrane as the separation membrane, a highly integrated separation membrane module with good contact efficiency can be manufactured. Furthermore, control and purification of the recovered gas concentration can be performed simultaneously because the hollow fiber membrane has gas selectivity.

DESCRIPTION OF SYMBOLS 1 Biological treatment apparatus 3 Biological treatment tank 5 Gas separation tank 7 Depressurization pump 9 Gas storage part 11 Holding carrier 13 Cooling means

Claims (6)

A biological treatment apparatus for treating a liquid to be treated by biological treatment,
A biological treatment tank for biologically treating the liquid to be treated to generate gas;
A gas separation tank that is disposed downstream of the biological treatment tank and receives a liquid to be treated biologically treated in the biological treatment tank , and is immersed in the liquid to be treated biologically treated in the biological treatment tank. A gas separation unit having a separation membrane that transmits gas generated in the treatment tank , and a decompression unit that depressurizes the inside of the gas separation unit; and
A gas storage section for storing the gas discharged from the biological treatment tank and the gas separation tank;
Control means for controlling the temperature of the liquid to be treated to a predetermined temperature,
The biological treatment apparatus, wherein the decompression means decompresses the inside of the gas separation means only when the temperature of the liquid to be treated becomes a predetermined temperature or lower. A biological treatment apparatus for treating a liquid to be treated by biological treatment,
A biological treatment tank for generating a gas to be treated liquid body by biological treatment,
And control means for controlling the temperature of the liquid to be treated body,
A gas separation means having a separation membrane immersed in a liquid to be treated biologically treated in the biological treatment tank and permeable to the gas;
Decompression means for decompressing the inside of the gas separation means;
A gas storage section for storing the gas discharged from the biological treatment tank and the gas separation means,
The biological treatment apparatus, wherein the decompression means decompresses the inside of the gas separation means only when the temperature of the liquid to be treated becomes a predetermined temperature or lower.   The biological treatment apparatus according to claim 1 or 2, wherein the temperature control means is a cooling device provided in the biological treatment tank.   The biological treatment apparatus according to any one of claims 1 to 3, wherein the gas separation membrane is a water-impermeable hollow fiber membrane.   The biological treatment apparatus according to claim 4, wherein the hollow fiber membrane is a gas selective permeable separation membrane. The liquid to be treated body by biological treatment, the gas generated by the biological treatment, is separated from the treated liquid using a gas separation membrane which is immersed in the treatment liquid that has been biologically treated to recover the separated gas organisms A processing method,
A biological treatment method comprising a decompression unit connected to the gas separation membrane, and performing gas separation while driving the decompression unit only when the liquid to be treated falls below a predetermined temperature.

Images