JP2008188552A - Method and device for treating organic waste - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and a device for treating organic waste by which the production of hydrogen from organic waste such as waste sludge and decomposition treatment for the organic waste can be efficiently and stably performed. <P>SOLUTION: The treatment method comprises: a fermentation stage where, with an adjustment liquid in which organic waste is diluted as nutrition, hydrogen production hyperthermophilic bacteria are reproduced at 60 to 105°C in an anaerobic atmosphere, for producing hydrogen from the bacterial cells; and a fermented sludge decomposition stage where, with the fermented residue formed in the fermentation stage as nutrition, activated sludge is reproduced in an aerobic atmosphere at ordinary temperature using an oxygen feeding means 31, thus, while the fermented residue is decomposed into carbon dioxide and water, the fermented residue is passed through a solid-liquid separation means 32, and liquid components passed through the solid-liquid separation means 32 are exhausted as waste water. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a processing method and a processing apparatus used to effectively use organic waste such as excess sludge, for example.

  The activated sludge method has been widely used as a method for treating sewage such as municipal sewage and industrial wastewater. In the activated sludge tank in which this activated sludge method is performed, it is said that about 200 million tons of excess sludge is generated annually. These surplus sludges are currently subjected to disposal such as incineration. However, not only disposal of surplus sludge, but also technological development that effectively utilizes surplus sludge, such as methane fermentation, is underway ( For example, see Patent Document 1).

JP 2003-1299 A

  By the way, hydrogen is attracting attention as clean energy, and there is a demand for technological development for efficiently producing hydrogen from excess sludge. However, at present, there is no promising system that can be put into practical use.

  The present invention has been made in view of the above circumstances, and its purpose is organic waste that can efficiently and stably produce hydrogen from organic waste such as excess sludge and decompose organic waste. The object is to provide a processing method and a processing apparatus for an object.

That is, the gist of the present invention is as follows.
[1] A fermentation process in which hydrogen-producing hyperthermophilic bacteria are grown at 60 to 105 ° C. and in an anaerobic atmosphere to produce hydrogen from the cells using nutritionally prepared liquid prepared by diluting organic waste. And the fermentation residue formed in the fermentation step as nutrition, the activated sludge is grown in an aerobic atmosphere using normal temperature and oxygen supply means, the decomposition of the fermentation residue into carbon dioxide gas and water, A fermentation residue decomposition step of passing the fermentation residue through solid-liquid separation means and discharging the liquid component that has passed through the solid-liquid separation means as waste water,
[2] The treatment method according to [1], wherein the hydrogen-producing hyperthermophilic bacterium is Thermococcus kodakaraensis KOD1 (FERM P-15007),
[3] An adjustment tank for storing the adjustment liquid;
A fermenter for performing a fermentation step with the hyperthermophilic bacterium, comprising a hydrogen-producing hyperthermophilic bacterium, a nitrogen supply means, and a gas outlet pipe for deriving the produced hydrogen to the outside of the tank;
A non-sludge wastewater treatment tank comprising an activated sludge, an oxygen supply means and a solid-liquid separation means, and a fermentation residue decomposition step;
An organic waste processing apparatus used for the processing method according to [1], comprising:
[4] The processing apparatus according to [3], wherein the hydrogen-producing hyperthermophilic bacterium is Thermococcus kodakaraensis KOD1 (FERM P-15007).

  According to the treatment method of the present invention, in the fermentation process, microorganisms contained in the supplied adjustment liquid can be sterilized, and various organic substances in the cells constituting the microorganisms can be used as nutrients. Therefore, hydrogen can be produced stably for a long time. In the fermentation residue decomposition step, even when hydrogen-producing hyperthermophilic bacteria are contained in the fermentation residue, the fermentation residue can be stably decomposed for a long time without being affected by the hyperthermophilic bacteria. it can.

  FIG. 1 is a schematic configuration diagram showing an example of an embodiment of the present invention. The organic waste treatment apparatus A includes an adjustment tank 1, a fermentation tank 2, and a non-sludge wastewater treatment tank 3 (hereinafter referred to as “drainage treatment tank 3”), and the adjustment tank 1, the fermentation tank 2, and the fermentation tank. 2 and the waste water treatment tank 3 are connected to each other by an adjustment liquid transfer pipe 4 and a fermentation residue transfer pipe 5.

  The adjustment tank 1 has a sealed structure having an internal space, and includes a waste transfer pipe 6 that leads from the outside of the tank to the inside of the tank. In the adjustment tank 1, the organic waste is transferred through the waste transfer pipe 6, and the concentration, pH, and the like are adjusted so as to be in a state suitable for the fermentation process in the next fermentation tank 2, and stored as the adjustment liquid. is doing. In the present invention, “organic waste” refers to discarded organic resources derived from living organisms, and examples thereof include excess sludge, raw garbage, human waste and the like.

  The fermenter 2 has a sealed structure having an internal space. The fermenter 2 is provided with hydrogen-producing hyperthermophilic bacteria in the tank, and has a nitrogen gas supply pipe 21 that leads from the outside of the tank to the inside of the tank and a gas that leads from the inside of the tank to the outside of the tank. A lead-out tube 22 is provided. Moreover, the heating part (not shown) for heating and heat-maintaining the fermenter 2 is provided from the trunk | drum to the bottom part.

  The hydrogen-producing hyperthermophilic bacterium is not particularly limited as long as it is capable of growing in an anaerobic atmosphere at 60 ° C. to 105 ° C. and has the ability to produce hydrogen using the above-mentioned adjustment liquid as a nutrient. Examples thereof include Thermococcus kodakaraensis, Pyricoccus furiosus, Thermotoga maritima, and the like. Among these, Thermococcus kodakaraensis is preferable because it is excellent in hydrogen production ability when the above-mentioned adjustment liquid is used as a nutrient. As Thermococcus kodakaraensis, Thermococcus kodakaraensis KOD1 is available. This strain is deposited at the National Institute of Advanced Industrial Science and Technology (currently the National Institute of Advanced Industrial Science and Technology, Patent Biological Deposit Center) under the accession number: FERM P-15007 (“Pyrococcus sp (Pyrococcus sp. .) KOD1 ”, but more precisely“ Thermococcus kodakaraensis KOD1 ”).

  The operation of the fermenter 2 is performed as follows. That is, in the heating unit, the temperature in the fermenter 2 is 60 to 105 ° C., more preferably 70 to 95 ° C., particularly preferably 80 to 90 ° C., and nitrogen gas is supplied from the nitrogen gas supply pipe 21. Is appropriately supplied to make the fermenter 2 a high temperature anaerobic atmosphere. Then, the adjustment liquid in the adjustment tank 1 is transferred into the fermentation tank 2 through the adjustment liquid transfer pipe 4, and this is used as a nutrient to grow hydrogen-producing hyperthermophilic bacteria, so that gas (hydrogen and Carbon dioxide). Subsequently, the produced gas is led out of the fermenter 2 through the gas lead-out pipe 22. The gas led out of the tank is then separated into hydrogen and carbon dioxide. The separated hydrogen is used in various applications such as a fuel cell vehicle, a hydrogen station, and a stationary fuel cell.

  According to the fermentation process performed in the fermenter 2, the microorganisms contained in the supplied adjustment liquid are sterilized at a high temperature of 60 to 105 ° C., and various organic substances in the cells constituting the microorganisms are leaked. Since it can be used as nutrition, hydrogen production by fermentation of hydrogen-producing hyperthermophilic bacteria efficiently proceeds, and the operation of the fermenter 2 can be performed stably for a long time.

  The waste water treatment tank 3 has an open structure having an internal space, and includes activated sludge, oxygen supply means 31 and solid-liquid separation means 32 in the tank, and is communicated with the solid-liquid separation means 32 and led out of the tank. A drain pipe 33 is provided.

  “Activated sludge” is not particularly limited as long as it can grow in an aerobic atmosphere at room temperature and can decompose the fermentation residue formed in the fermenter 2. In addition to normal activated sludge, the decomposition efficiency of fermentation residue In order to increase the amount of the fermentation residue, a suitable one can be used depending on the type of fermentation residue, that is, the type, properties, etc. of the organic waste and the hydrogen-producing hyperthermophilic bacterium.

  For example, when processing organic waste containing a large amount of oils and fats, known oil-degrading bacteria can be used. Among these, when it is desired to increase the decomposition efficiency of oil and fat, the oil and fat-degrading bacilli described in JP-A-2001-61468 by the present inventor is suitable. Moreover, when processing the organic waste containing polyvinyl alcohol (PVA), a well-known PVA degrading bacterium can be used. Among these, when it is desired to increase the degradation efficiency of PVA, the PVA-degrading bacterium described in JP-A-2006-180706 by the present inventor is suitable.

  As representative examples of the oil-degrading gonococci, Bacillus subtilis FERM BP-7270 and Bacillus subtilis FERM BP-7271 may be mentioned (Institute of Industrial Technology Life on August 11, 1999, respectively) (Deposited at the National Institute of Engineering and Technology (currently: National Institute of Advanced Industrial Science and Technology Patent Biological Depositary), and transferred from the original deposit to the deposit under the Budapest Treaty on August 10, 2000).

  Representative examples of the PVA-degrading bacterium include Pseudomonas FERM P-19204 strain, Acinetobacter IAM-3 strain, and IAM-4 strain. Pseudomonas FERM P-19204 strain was deposited on February 7, 2003 at the National Institute of Advanced Industrial Science and Technology Patent Biological Depositary Center. In addition, Acinetobacter IAM-3 and IAM-4 strains are stored at Kyoto University Graduate School of Engineering (Yoshida Honmachi, Sakyo-ku, Kyoto City) and distributed upon request.

  When using Thermococcus kodakaraensis KOD1 described above as a hydrogen-producing hyperthermophilic bacterium, activated sludge, for example, a halophilic salt formed in a wastewater treatment facility of a soy sauce factory or seawater product treatment plant Activated sludge containing bacteria can be used. Further, if a water supply pipe for supplying water is separately provided in the waste water treatment tank 3 and the fermentation residue transferred to the waste water treatment tank 3 is diluted about 3 to 5 times, normal activated sludge is used. You can also.

  The oxygen supply means 31 includes an air introduction pipe 31a and an oxygen supply unit 31b, and is configured to send oxygen taken from outside the tank into the tank. The oxygen supply means 31 is not particularly limited as long as it can send oxygen into the tank, and examples thereof include an air pump.

  The solid-liquid separation means 32 enables wastewater treatment with high-concentration microorganisms exceeding about 13,000 ppm by solid-liquid separation. As the solid-liquid separation means 32, for example, a microfiltration membrane, an ultrafiltration membrane, a reverse osmosis membrane or the like can be used. Typically, a metal film is used as the solid-liquid separation means. For example, the metal film is produced by spraying stainless metal particles onto a stainless steel wire net and sintering. This solid-liquid separation metal membrane has physical strength not found in resin membranes and can be used even under severe conditions. In summary: (1) High heat resistance and steam sterilization at 121 ° C; (2) High chemical resistance; can be washed with strong alkalis and strong acids; (3) Organic solvents can be handled ; (4) High mechanical strength and highly viscous fluids can be handled; (5) The membrane itself is not assimilated by microorganisms and does not need to be immersed in a bacteriostatic agent during storage; Etc. If fouling of the film occurs, decomposition of the organic component by alkali and dissolution of the inorganic scale by acid may be performed. The deterioration of function due to deterioration is almost negligible. The metal film is a porous film, and typically has a pore size of about 0.2 μm in diameter.

  The operation of the waste water treatment tank 3 is performed as follows. That is, by supplying oxygen into the tank from the oxygen supply means 31, the inside of the wastewater treatment tank 3 is brought to a normal temperature aerobic atmosphere, and the fermentation residue in the fermentation tank 2 passes through the fermentation residue transfer pipe 5 in the wastewater treatment tank 3. It is transferred to. Then, by allowing activated sludge to grow using the fermentation residue transferred into the wastewater treatment tank 3 as nutrition, the fermentation residue is passed through the solid-liquid separation means 32 while decomposing the fermentation residue into carbon dioxide gas and water. The liquid component that has passed through the liquid separation means 32 is discharged as waste water.

  According to the fermentation residue decomposition process performed in the wastewater treatment tank 3, since it is performed at room temperature and in an aerobic atmosphere, even if the hydrogen-producing superthermophilic bacteria are transferred to the wastewater treatment tank 3 together with the fermentation residue, Since the hyperthermophilic bacteria cannot grow and only activated sludge can grow, not only fermentation residues but also hydrogen-producing hyperthermophilic bacteria can be decomposed, and the operation of the waste water treatment tank 3 is also stable for a long time. It can be carried out.

  Although the fermentation residue decomposition step has been described above, in order to further increase the decomposition efficiency of the fermentation residue, in addition to the oxygen supply unit 31, a fine bubble generation unit may be provided.

  Typically, the fine bubble generating means can generate fine bubbles (ultrafine bubbles) having a diameter (φ) smaller than about 3 μm. As the fine bubble generating means, for example, an ultrafine bubble generating device (Suzuki Sangyo Co., Ltd., 5 Yamada Nakayoshimi-cho, Nishikyo-ku, Kyoto-shi, 6), an air diffuser described in JP-A-2001-314888, and the like are used. Can do. For example, an air diffuser described in Japanese Patent Application Laid-Open No. 2001-314888 has a bell-shaped gas-liquid mixing tube, generates an ultra-high speed spiral flow, and collides with a protrusion disposed on the upper part (upper hemisphere). Releases fine bubbles. As a result, a highly diffused eddy current containing a large amount of dissolved oxygen can be convected into the wastewater treatment tank 3.

  The ultrafine bubbles are bubbles having a diameter of 0.1 μm to 3 μm and smaller than the fine bubbles (diameter is 10 to 100 μm). Since the ultrafine bubbles have a small diameter, their buoyancy is small, and they are placed on the swirling water flow and easily trapped in the downward flow in the wastewater treatment tank 3, thereby retaining in the treatment tank 3, and the wastewater treatment tank 3 is uniformly diffused. Thereby, the fine bubbles are not dissolved in water, but rather dispersed and suspended in water, and may be present in water at a concentration corresponding to 180 to 200 ppm.

The fine bubble generating means may be connected to an oxygen supply device, thereby providing a higher concentration oxygen environment. The high-concentration oxygen supply means including the fine bubble generation means and the oxygen supply device can dissolve oxygen having a purity of about 93% at a concentration of 180 ppm, and inject oxygen into bubbles having a diameter of about 3 μm, thereby The BOD treatment capacity is about 10 times that of the conventional activated sludge process. For example, the standard activated sludge BOD volume load 0.5~1.5kg / ^{m 2} · day, may increase to approximately 5 kg / ^{m 2} · day.

  In FIG. 1, the present invention has been described using the batch processing apparatus A. However, the present invention may be a continuous type as well as a batch type. That is, in the case of configuring a continuous treatment apparatus, for example, in the treatment apparatus A shown in FIG. 1, the wastewater treatment tank 3 and the adjustment tank 1 are connected by a pipe line, and the fermentation is in the wastewater treatment tank 3. What is necessary is just to make it perform a fermentation process and a fermentation residue decomposition | disassembly process, returning a residue to the adjustment tank 1 grade | etc.,.

  As described above, the embodiment of the present invention has been described. However, in the apparatus shown in FIG. 1, the present inventor uses surplus sludge as the organic waste, and thermococcus Using activated sludge formed in the wastewater treatment facility of Kodakaraensis (Thermococcus kodakaraensis) KOD1 (FERM P-15007) and soy sauce factory, fermenter 2 is controlled at 85 ° C and wastewater treatment tank 3 is controlled at room temperature. When the apparatus A was operated, it was confirmed that hydrogen can be stably produced for a long time in the fermenter 2 and that the fermentation residue can be stably decomposed for a long time in the wastewater treatment tank 3.

  INDUSTRIAL APPLICABILITY The present invention can be widely used as an organic waste processing method and processing apparatus having hydrogen production capability.

It is a schematic structure figure showing an example of an embodiment of the present invention.

Explanation of symbols

A treatment apparatus 1 adjustment tank 2 fermenter 3 waste water treatment tank 21 nitrogen supply means 22 gas outlet pipe 31 oxygen supply means 32 solid-liquid separation means

Claims (4)

Fermentation process for producing hydrogen from the cells by growing hydrogen-producing hyperthermophilic bacteria under an anaerobic atmosphere at 60 to 105 ° C., using nutritionally prepared organic waste solution as a nutrient,
While fermenting activated sludge under normal temperature and an aerobic atmosphere using an oxygen supply means using the fermentation residue formed in the fermentation process as nutrition, the fermentation residue is decomposed into carbon dioxide gas and water while the fermentation residue is decomposed. Through a solid-liquid separation means, and a fermentation residue decomposition step for discharging the liquid component that has passed through the solid-liquid separation means as waste water,
A method for treating organic waste.   The processing method according to claim 1, wherein the hydrogen-producing hyperthermophilic bacterium is Thermococcus kodakaraensis KOD1 (FERM P-15007). An adjustment tank for storing the adjustment liquid;
A fermenter for performing a fermentation step with the hyperthermophilic bacterium, comprising a hydrogen-producing hyperthermophilic bacterium, a nitrogen supply means, and a gas outlet pipe for deriving the produced hydrogen to the outside of the tank;
A non-sludge wastewater treatment tank comprising an activated sludge, an oxygen supply means and a solid-liquid separation means, and a fermentation residue decomposition step;
The processing apparatus of the organic waste used for the processing method of Claim 1 which comprises.   The processing apparatus according to claim 3, wherein the hydrogen-producing hyperthermophilic bacterium is Thermococcus kodakaraensis KOD1 (FERM P-15007).

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