JP2013013896A - Anaerobiotic treatment method and device of organic waste - Google Patents

Abstract

PROBLEM TO BE SOLVED: To optimize a biological treatment process which easily and efficiently makes an organic solid soluble and decomposes it into a low molecule in a short time by utilizing a reaction characteristic of an anaerobiotic microorganism, to a hydrogen-methane two-stage fermentation treatment process of garbage-based organic waste.SOLUTION: In this anaerobiotic treatment process and its device, in garbage-based organic waste treatment in which sugar-based waste is a main component or in garbage-based organic waste treatment including a cellulose solid, hydrogen and methane are biologically recovered which are returned to a process in which complete-mixture type solubilization and hydrogen fermentation for treating a raw material which is refined and homogenized in a preceding process and whose density is VS 5 to 15 wt.% by a biological reaction at 30 to 70°C, pH 5 to 8.5 and at a hydraulic retention time of 2 to 3 days in a font stage are combinedly performed, and a process in which a two-stage fermentation method composed of a complete-mixture type methane fermentation process at a succeeding rear stage is performed, and the anaerobiotic solubilization and hydrogen fermentation for solubilizing and fermenting a part of a flow-out component from a methane fermentation process are combinedly performed.

Description

  The present invention relates to a method and apparatus for anaerobic treatment of organic waste such as sewage sludge, surplus sludge, livestock manure, food waste, food production waste, etc., by a two-stage fermentation method of hydrogen fermentation and methane fermentation, and in particular, anaerobic Organic waste anaerobic, characterized by having both a biological treatment process and a hydrogen fermentation process that easily and efficiently solubilizes and lowers the molecular weight of organic solids in a short period of time using the reaction characteristics of microbial microorganisms The present invention relates to a sex processing method and apparatus.

In recent years, anaerobic treatment methods (methane fermentation methods) targeting organic wastewater and waste (biomass) have been attracting attention with the aim of building a resource recycling society. This means that biomass energy such as methane gas and hydrogen gas can be biologically converted from wastewater / waste, that liquid fertilizers and compost resources can be recovered, that mild biological reactions are used, and that they do not depend on incineration. This is because it has features such as that it can contribute to CO ₂ reduction derived from fossil fuels.

  On the other hand, in the methane fermentation technology, in organic wastewater systems, speeding up and expanding the use of wastewater are R & D issues, and in organic waste, solid solubilization and improvement in methane gas conversion rate are listed as R & D issues. Various techniques have been proposed. At the present stage, although technological innovation is progressing by applying high-speed organic wastewater treatment by UASB (upward flow anaerobic sludge blanket) method and high-temperature methane fermentation method of organic waste, There is still no sufficient solution for solubilization technology. In particular, regarding the unused biomass resources that will become the most important in the future in the resource circulation, the solubilization and low molecular weight technologies for cellulose components and sludge, which occupy most of them, are not yet established.

  In addition, research and development issues in hydrogen fermentation technology include technologies for hydrogen fermentation from soluble carbohydrates such as glucose, starch, and sucrose using Clostridium bacteria, Enterobacter bacteria, Bacillus bacteria, and anaerobic enrichment cultures. Various proposals have been made. In addition, hydrogen fermentation technology for organic solid waste is not established, target organic matter that can be converted to hydrogen gas is limited to glucose and starch, hydrogen fermentation for organic solid waste Many research and development issues remain, such as the lack of control technology.

Furthermore, for organic waste liquids, a method for anaerobically recovering hydrogen gas and methane gas using a biogas generator that combines hydrogen fermentation and methane fermentation via piping has been proposed. No efficient technical proposal has been made for objects (see, for example, Patent Document 1).
In addition, when anaerobically treating dense organic wastewater, sludge, sewage sludge, etc. to stabilize minerals, hydrogen and methane are separately produced and recovered for effective use of energy and improved treatment efficiency and A technology related to an anaerobic treatment device that enables stabilization of operation is registered as a patent (Japanese Patent No. 3191400). This consists of an acid generation tank for receiving organic wastewater and generating acid, a methane generation tank for receiving a part of the effluent of the acid generation tank and generating methane, and a part of the effluent of the acid generation tank. Receiving and reducing pressure to transfer the dissolved gas to the gas phase, means for returning the liquid in the pressure reduction tank to the acid generation tank, and recovering hydrogen from the gas phase discharged from the pressure reducing tank with an aqueous storage alloy An anaerobic treatment device characterized in that it is provided with a means for carrying out the above, but is not a proposal relating to the solubilization / hydrogen fermentation technology which is one of the subjects of the present invention.

  In the case of targeting such organic waste, conventionally known methods for solubilizing and reducing the molecular weight of organic solids (hereinafter referred to as pretreatment) include physicochemical treatment as blasting. There are many known methods such as a method, an ultrasonic crushing method, a wet oxidation method, a wet mill method, a heat treatment method, an alkali treatment method, a thermal alkali treatment method, and an ozone treatment method. As biological treatment methods, microbial treatment methods, enzyme treatment methods and the like are known.

  Among these, physicochemical pretreatment is a waste treatment because of the large amount of energy input, the consumption of chemicals such as acids and alkalis, and the heavy burden of cost and maintenance on equipment. The current situation is that it is not fully satisfactory in terms of cost effectiveness when viewed as a hydrogen fermentation / methane fermentation system. On the other hand, representative examples of biological pretreatment include enzyme treatment and microbial treatment. In the former, although various industrial enzymes are becoming highly active and inexpensive due to the recent use of gene recombination technology, (1) the target solids are limited, (2) The action and effect differ depending on the properties of the solid, and (3) the action is likely to proceed with relatively easily degradable solids, but problems still remain with persistent solids. In the microorganism treatment method, a method of adding a specific useful microorganism species or group of microorganisms such as Clostridium bacterium, Enterobacter bacterium, Bacillus bacterium, anaerobic enrichment culture, etc. (bioaugmentation), There is a known method (biostimulation) that activates multiplication by adjusting the nutritional requirements and growth environment of useful microorganisms, but it has not reached a practically applicable technology. .

  Furthermore, there is also a technique for promoting solubilization and low molecular weight solids by maintaining the concentration of anaerobic sludge or microorganisms in the decomposition tank (reaction tank) at a high concentration using a separation membrane. From an engineering point of view, the aim is to promote microbial degradation by increasing the SRT (sludge residence time) without changing the HRT (hydraulic residence time). However, when separation membrane technology is applied to organic waste, there are many practical problems such as clogging of the separation membrane and foaming problems, and the initial cost and running cost are also high. It is not.

JP 2001-149983 A

  Thus, in the two-stage fermentation process of organic waste hydrogen fermentation and methane fermentation, the key is efficient conversion of solids to hydrogen gas and methane gas.・ Low molecular weight technology is the biggest key to controlling fermentation performance. Accordingly, there is a demand for the construction of a hydrogen / methane two-stage fermentation process with more efficient solubilization and molecular weight reduction processes.

  In view of such conventional problems, the present invention is a method for subjecting organic waste containing solids such as sewage sludge, surplus sludge, livestock manure, garbage, food production waste, etc., to hydrogen fermentation and methane fermentation In particular, the biological treatment process that efficiently and efficiently solubilizes and lowers the molecular weight of organic solids in a short time using the reaction characteristics of anaerobic microorganisms is optimized for the hydrogen / methane two-stage fermentation process It is intended to provide a method.

  The inventors of the present invention focused on organic solids and intensively studied the efficient solubilization method and hydrogen fermentation method. First, based on a case study of high-temperature methane fermentation of organic waste, we analyzed and considered the organic matter decomposition reaction and microbial characteristics. The inventors have devised a solubilization / hydrogen fermentation process utilizing the anaerobic microbiological characteristics to complete the present invention.

That is, the present invention achieves the above object with the following configuration.
(1) In garbage-based organic waste processing mainly consisting of saccharide-based waste or garbage-based organic waste processing containing cellulosic solids, the concentration is reduced and homogenized in the pretreatment process. Completely mixed anaerobic solubilization and hydrogen fermentation treated with a biological reaction of 30 to 70 ° C., pH 5 to 8.5, hydraulic residence time 2 to 3 days for the raw material of VS 5 to 15 wt% And a two-stage fermentation method consisting of a fully mixed methane fermentation process in the subsequent stage, and a part of the effluent from the methane fermentation process is returned to the process that combines anaerobic solubilization and hydrogen fermentation. An anaerobic treatment method for biologically recovering hydrogen and methane, characterized by:

  (2) Garbage organic waste treatment mainly composed of saccharide-based sugar waste or garbage organic waste treatment equipment containing cellulosic solids, which is refined and homogenized in the pretreatment process An anaerobic solubilization process in which a raw material tank in which a raw material whose concentration is adjusted to 5 to 15 wt% is placed, and a biological reaction is performed at 30 to 70 ° C., pH 5 to 8.5, hydraulic residence time 2 to 3 days in the previous stage A two-stage fermentation method with a fully mixed anaerobic solubilization / hydrogen fermenter that performs a process that combines hydrogen fermentation and a methane fermenter that performs a fully mixed methane fermentation process at the subsequent stage A return pipe is provided for returning a part of the effluent component from the methane fermenter to the anaerobic solubilization / hydrogen fermenter for performing a process having both anaerobic solubilization and hydrogen fermentation. Biologically recover hydrogen and methane That anaerobic treatment apparatus.

  According to the method and apparatus for anaerobic treatment of organic waste of the present invention, a step having both anaerobic solubilization and hydrogen fermentation in the previous stage of the treatment of organic waste, followed by a two-stage consisting of a methane fermentation process in the subsequent stage Biologically recovering hydrogen and methane by fermentation, organic solids can be easily and efficiently solubilized and reduced in molecular weight in a short time, resulting from organic waste treatment While reducing BOD and COD of organic waste liquid, hydrogen and methane can be produced as biogas. Even if most of the organic matter in the raw water is carbohydrate organic waste or solid matter such as cellulose, the hydraulic residence time in the anaerobic solubilization / hydrogen fermentation process is 2 to 3 days. It can be processed.

  Hereinafter, the present invention will be described in more detail, but the present invention is not limited thereto. Hereinafter, the solubilization / hydrogen fermentation method and the methane fermentation method will be described for convenience, but the present invention is not limited thereto.

(1) Pretreatment conditions In the organic waste treatment method according to the present invention, the step preceding the step having both anaerobic solubilization and hydrogen fermentation (hereinafter also referred to as “solubilization / hydrogen fermentation step” for the sake of simplicity) Refinement and homogenization of raw materials by physical crushing is very effective for biological reactions in the subsequent solubilization / hydrogen fermentation process and methane fermentation process. Especially for solid organic wastes of different sizes, such as food waste, food processing waste, cooking residue, and paper waste, stone mill crushing, minc crushing, shredder crushing, cutter pump crushing, etc. It is preferable to refine the solid shape by providing a solid. As a crushing process, after roughly crushing the raw material, the organic substance concentration (VS concentration, volatile solids) is 1 to 20 wt.% Using a sewage, drainage, tap water, hydrogen / methane fermentation process treated water, etc. in a raw material adjustment tank equipped with an underwater stirrer. %, Preferably 5 to 15 wt%, and is preferably refined and homogenized. Furthermore, the slurry is preferably refined and homogenized with a stone mill type grinder or the like. As a mechanical device used for such a crushing process, for example, a coarse crusher can be roughly crushed to a particle size of 5 to 20 mm with a high-speed crusher RSC series (manufactured by Nippon Ealing Co., Ltd.), and an underwater mixer SM series ( Shin Meiwa Kogyo Co., Ltd.) can be slurried and homogenized to a VS concentration of 1-15%, and using a stone mill grinder Serendipita MKCA series (Masuyuki Sangyo Co., Ltd.), the particle size can be increased at high speed. Wet refinement can be performed to 1 to 0.1 mm.

(2) Solubilization / hydrogen fermentation conditions In the solubilization / hydrogen fermentation process of the organic waste treatment according to the present invention, the reaction temperature is 30 to 70 ° C., the pH is 5 to 8.5, and the hydraulic residence time (HRT) is 0. It is preferable to carry out in 2 to 5 days. In particular, depending on the type of organic waste, the solubilization stage tends to be rate-determining. Therefore, it is preferable to perform HRT for 3 to 5 days by a high-temperature reaction at a reaction temperature of 45 to 70 ° C. This is because heat treatment by high-temperature reaction and solubilization by thermophilic organisms are achieved at the same time, and furthermore, by selectively controlling HRT in this process, hydrogen producing microorganisms that usually have high growth rate ability are selectively dominant. This enables an anaerobic solubilization and hydrogen fermentation process.

  In this solubilization / hydrogen fermentation process, the solubilized organic waste quickly proceeds to hydrolysis and acid fermentation, so anaerobic fermentation such as lactic acid fermentation, acid fermentation, and hydrogen fermentation is almost simultaneously performed. It will be a progressive form. Therefore, the solubilization / hydrogen fermentation process requires fermentation environment conditions in which solubilized bacteria and hydrogen-producing bacteria predominately coexist. However, depending on the type of organic waste, lactic acid-fermenting bacteria predominate or propionic acid-producing bacteria often act. In order to promote the recovery of hydrogen gas by dominating anaerobic hydrogen-producing bacteria in such an environment, the doubling time of many anaerobic hydrogen-producing bacteria must have a very fast growth rate of 4 to 24 hours. It is optimal to perform fermentation operation by dividing the inside of the solubilization / hydrogen fermenter into two chambers of a solubilization phase and a hydrogen fermentation phase based on the HRT control conditions. In this case, the setting conditions of the solubilization phase and hydrogen fermentation phase inside the solubilization / hydrogen fermenter differ depending on the type of organic waste. The hydrogen fermentation process may be operated with an HRT of 0.2 to 2 days, preferably 0.2 to 1 day, and a solubilization process with an HRT of 3 to 4.8 days, preferably 1.5 to 2.5 days. Is preferred.

  Furthermore, in order to dominate hydrogen-fermenting bacteria, a method of introducing an anaerobic hydrogen-producing microorganism belonging to the genus Clostridium into a solubilizing / hydrogen-fermenting tank is also effective. For example, it is effective to use an anaerobic hydrogen-producing bacterium Clostridium butyricum SC-E1 strain (Accession No .: FERM P-14790). When introducing an anaerobic hydrogen-fermenting bacterium into a fermenter, it is preferable to add the microbial cell in liquid or powder form. The rate of addition varies depending on the type of organic waste and the concentration of the cells, but as a guideline, it is 0.01 to 0.5 vol%, preferably 0.02 to 0.2 vol% with respect to the reaction volume of hydrogen fermentation. is there

(3) Methane fermentation conditions In the methane fermentation process of organic waste treatment according to the present invention, the reaction treatment format is floating bed type, fixed bed type, fluidized bed type, UASB (upflow anaerobic sludge blanket). Although it is applicable to any type, it is necessary to select according to the raw material properties supplied from the solubilization / hydrogen fermentation process. In this selection, it is necessary to pay particular attention to the SS concentration (Suspended Solids) and the oil and fat concentration. Specifically, when the SS concentration is 2,000 mg / liter or more, it is preferable to apply floating bed type methane fermentation. In addition, when the oil and fat concentration is 1,000 mg / liter or more, it is preferable to apply floating bed type methane fermentation.

  Regarding the operation method in a methane fermentation process, fermentation temperature is 30-70 degreeC, Preferably it is a high temperature methane fermentation area | region of 50-65 degreeC, Most preferably, it carries out at 50-60 degreeC. This is because the optimum temperature for growth of many thermophilic methanogenic microorganisms and other anaerobic bacteria is within these ranges. In the fermenter, neutral fats and higher fatty acids have higher dispersibility at higher temperatures. Therefore, when applying waste materials that contain a large amount of fat and oil components, a high-temperature methane fermentation method of 50 to 65 ° C. It is preferable to select. Moreover, the suitable pH at the time of methane fermentation is pH 5-8.5, Most preferably, it is pH 6.5-8.5.

  In a methane fermentation method packed with a microorganism-supporting carrier such as a fixed bed type or a fluidized bed type, a binding method or a comprehensive method can be applied as a method for binding microorganisms to the carrier, but in the microbial reaction in the methane fermentation process of the present invention, sand is used. Organisms by attaching microbes to particles such as silica sand, activated carbon, ceramics, synthetic resin, plastic beads, glass beads, polyethylene glycol, polyvinyl alcohol, polyurethane, polypropylene, sludge incineration ash, charcoal powder, coal ash fly ash It is advantageous to form a film. These holding carriers are roughly classified into a fixed bed and a fluidized bed depending on the form of existence in the anaerobic treatment tank and the flow state, but both types can be applied in the present invention. However, in the fixed bed type, clogging of the immobilized carrier and sludge levitation due to excessive adhesion of oils and fats, and in the fluidized bed type, separation of sludge microorganisms adhering to each other due to collision between the carriers is likely to be a problem. It is necessary to pay attention to properties such as fat and oil concentration and solid matter concentration, raw water supply method during fermentor operation, organic matter load, sludge concentration and sludge properties. In determining these operating conditions, the operating conditions are determined in consideration of the raw water condition, the amount of water fluctuation, and the target treated water quality.

(4) Return method The method of returning part of the effluent components from the methane fermentation process to the solubilization / hydrogen fermentation process is to remove anaerobic sludge such as solubilized / hydrogen fermentation sludge or methane fermentation sludge that has flowed out of the anaerobic treatment process. The method of returning as it is and the method of concentrating the discharged anaerobic sludge by gravity sedimentation or mechanical concentration and returning the concentrated sludge to the solubilization / hydrogen fermenter are applied. In this sludge concentration step, a method for promoting sludge concentration / aggregation by adding 0.1 to 1.0 wt% of a polymer coagulant such as a polymer coagulant per SS to the spilled sludge is also effective. In addition, as a mechanical concentration method, those used as a sludge dehydrator such as a centrifugal dehydrator or a screw press dehydrator can be applied. Moreover, when dewatered sludge is returned to the solubilization / hydrogen fermenter, there is no problem in introducing the sludge dehydrated by these dehydrators.

  It is also effective to introduce aerobic sludge such as surplus activated sludge from the outside. This is because sludge mainly composed of microorganisms such as surplus activated sludge also acts as a nutrient source for microorganisms in anaerobic treatment, and thus is effective in improving the efficiency of organic matter decomposition and promoting digestion. In this case, in the introduction of microorganisms, sludge is subjected to ultrasonic crushing, wet mill crushing, ball mill crushing, homogenizing crushing, heat treatment, high-temperature high-pressure treatment, hydrothermal treatment, hydrothermal treatment in a supercritical or subcritical region, acid or alkali treatment, It is more effective to introduce into the solubilization / hydrogen fermentation process after performing physical and chemical crushing treatments typified by ozone oxidation.

  On the other hand, when returning a part of the effluent from the methane fermentation process to the solubilization / hydrogen fermentation process for the purpose of supplying alkali to the solubilization / hydrogen fermentation process, It is also effective to return concentrated separated water (supernatant) or dehydrated filtrate. In particular, in the solubilization / hydrogen fermentation process, a large amount of lower fatty acids (formic acid, acetic acid, propionic acid, lactic acid, butyric acid, valeric acid, caproic acid, etc.) are produced, and in most cases, the pH drops to about 3 to 5. Therefore, the effect of returning concentrated separated water (supernatant) and dehydrated filtrate from the methane fermentation process is great.

Next, embodiments of the present invention will be described with reference to the drawings.
Note that components having the same function are denoted by the same reference symbols throughout the drawings for describing the embodiments.

FIG. 8 is a block diagram showing conventional organic waste methane fermentation.
That is, FIG. 8 is a block diagram for explaining a methane fermentation method, which is a conventional one-stage fermentation method, and is also a block diagram showing a material balance of a processing example of garbage 10 t / day.
In the one-stage fermentation method, the garbage 4 is introduced into the methane fermentation tank 2 together with the dilution water 8 to generate the biogas 9 by the methane-producing bacteria and discharge the fermentation residue 10 out of the system. The case where the garbage is treated at 10 t / day will be described as an example. The garbage 4 uses a methane-producing fungus in the methane fermentation tank 2 and is subjected to high temperature methane fermentation at 55 ° C. for a hydraulic residence time (HRT) of 20 to 25. Methane is fermented in a day to generate biogas 9 at 850 to 1000 m ³ / day. The proportion of methane in biogas 9 was 60%.

FIG. 1 is a block diagram showing one embodiment of an organic waste hydrogen / methane two-stage fermentation apparatus according to the present invention.
In FIG. 1, a solubilization / hydrogen fermentation tank 1 is provided as a preceding stage of the organic waste treatment, and a methane fermentation tank 2 is provided as a subsequent stage.

In the hydrogen / methane two-stage fermentation method, the garbage 4 is first introduced into the solubilization / hydrogen fermenter 1 together with the diluting water 8 and subjected to anaerobic fermentation to decompose organic matter, and hydrogen and methane raw material organic matter such as organic acid or Produces alcohol. The methane raw material organic matter generated in the solubilization / hydrogen fermenter 1 is introduced into the methane fermenter 2, and the methane raw organic matter is decomposed by the methane-producing bacteria to produce methane and carbon dioxide, and the fermentation residue 10 is discharged out of the system. To do. If the case where a garbage is processed 10t / day is demonstrated to an example, the garbage 4 will be anaerobic-treated for HRT 1-3 days in the solubilization and hydrogen fermenter 1 of the temperature of 30 degreeC, and hydrogen and a methane raw material organic substance will be produced | generated. Methane raw material organic matter generated in the solubilization / hydrogen fermenter 1 is introduced into the methane fermenter 2, high temperature methane fermentation at 55 ° C. is carried out for 10 to 15 days, and biogas 9 is generated at 1,100 to 1,300 m ³ / day. To do. The proportion of methane in biogas 9 was 60% and the proportion of hydrogen was 2-3%.

FIG. 2 is a block diagram showing an embodiment of an organic waste solubilization / hydrogen fermentation apparatus according to a reference example of the present invention.
The hydrogen / methane two-stage fermentation apparatus includes a solubilization / hydrogen reactor 1 divided into a solubilization fermentation unit 1A and a hydrogen fermentation unit 1B, and a methane reactor 2 that performs methane fermentation. The organic waste 7 is introduced into the solubilization / hydrogen reactor 1, but the easily decomposable waste 5 can be introduced into the hydrogen fermentation unit 1B, and the hardly decomposable waste 6 can be introduced into the solubilization unit 1A. In addition, a physicochemical reactor is provided after the methane reactor 2, and the generated hydrogen is used as biogas, and part of it is returned to the hydrogen fermentation unit 1B and the methane reactor 2 for use in hydrogen fermentation and methane fermentation, respectively. It can also be configured to. In addition, it cannot be overemphasized that the fermentation residue 10 may receive the further process by a fermentation residue processing process.

FIG. 3 is a schematic view showing another embodiment of the organic waste solubilization / hydrogen fermentation apparatus according to the present invention.
The embodiment shown in FIG. 3 is a block diagram of a process for treating raw water 4A containing organic waste 7 instead of the above-described garbage 4. Solubilization of the organic waste in the raw water 4A is introduced into the hydrogen fermenter 1 and the anaerobic sludge 12 in the methane fermenter 2 is solubilized in order to make the treatment in the hydrogen fermenter 1 efficient. It is characterized by having means for returning to the hydrogen fermenter 1. In order to efficiently perform solubilization in the solubilization / hydrogen fermenter 1 and hydrogen fermentation by hydrogen-producing bacteria or the like, the pH of the tank 1 is generally maintained at about 5.5 to 7.

FIG. 4 is a schematic diagram showing a first embodiment of an indoor experiment using the organic waste hydrogen / methane two-stage fermentation apparatus according to the present invention.
In the embodiment shown in FIG. 4, the methane fermentation tank 2 shown in FIG. 3 is changed to a high-temperature methane fermentation tank 2A, and the treatment days, that is, the HRT is shortened. The anaerobic sludge 12 from the high-temperature methane fermentation tank 2A is sludge. Divided into liquid 13 and solid content 14 and returned separately to the solubilization / hydrogen fermentation tank 1, while maintaining the pH of the tank 1 at about pH 6 and introducing only the supernatant 11 into the high-temperature methane fermentation tank 2. This is a further improvement in the efficiency of two-stage fermentation.

FIG. 5 is a schematic view showing a second embodiment of the laboratory experiment using the organic waste hydrogen / methane two-stage fermentation apparatus according to the reference example of the present invention.
The embodiment shown in FIG. 5 illustrates an example in which the Clostridium butyrium SC-El strain is used as a hydrogen-producing bacterium in order to further improve the treatment efficiency of the solubilization / hydrogen fermenter 1 in the step shown in FIG. It is a process outline figure for doing.
FIG. 6 is a schematic view showing an embodiment of an outdoor experiment using the organic waste hydrogen / methane two-stage fermentation apparatus according to the present invention.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not restrict | limited at all by these Examples.

Example 1
Continuous experiments of hydrogen / methane two-stage fermentation were conducted using simulated food waste (Table 1) and food leftovers (factory A, 3,000 people, Table 2). For the preparation of the experimental materials, the mixture was mixed with simulated garbage or canned food: tap water = 1: 1 (weight ratio), and crushed with a blender (Model LBC-10 type; Waring) for about 3 minutes. Table 3 shows the water quality of the raw materials adjusted by crushing treatment.
The experimental equipment is a fully mixed solubilization / hydrogen fermenter (Tokyo Rika Kikai Co., Ltd. Jar Fermenter MBF, total volume 2.5L, operating volume 1.0L, jacket hot water circulation type) and methane fermenter (cylindrical) Type, made of vinyl chloride, total volume 4.5L, effective volume 3.5L, jacket hot water circulation type). In the experiment, continuous operation of solubilization / hydrogen fermentation and methane fermentation was performed under high temperature fermentation conditions at 55 ° C. The operating conditions of the experimental apparatus were 55 ° C. for both the solubilization / hydrogen fermenter and the methane fermenter. The raw water input was 300 mL / day, the hydraulic residence time (HRT) was 2.5-3 days for solubilization / hydrogen fermentation, and 12 days for methane fermentation.
In addition, as a comparative experiment, simulated garbage and leftovers from the cafeteria were continuously operated on a HRT 18 day by one-stage high-temperature methane fermentation.

The analysis was performed by the following method.
・ TS (Total Solids): 105 ℃ evaporation residue weight (JIS K 0102)
・ VS (Volatile Solids, loss on ignition): 600 ° C loss on ignition (JIS K 0102)
COD _Cr (chemical oxygen demand): potassium dichromate method (JIS K 0102)
・ BOD (Biochemical Oxygen Demand): Winkler ・ Modified Sodium Azide (JIS K 0102)
・ TOC (Total Organic Carbon): Shimadzu TOC-500 meter ・ Protein: (Kjeldahl Nitrogen-Ammonia Nitrogen) x 6.25
・ Total reducing sugars: phenol-sulfuric acid method (absorbance 488nm)

・ Cellulose substance: Weight measurement by ethanol / benzene extraction method ・ Lipid: Hexane: Isopropanol (5: 3) extraction method using mixed solvent (hexane extract is calculated from the weight of the extracted substance after drying at 80 ℃)
・ Volatile organic acid (VFA): High performance liquid chromatograph (Elmer Optics ERC-8710, detector RI, column Shodex Ionpack KC-811, column temperature 60 ° C, mobile phase 0.1% phosphoric acid 0.7ml / min)
・ Methane gas and carbon dioxide gas chromatograph (GL Science GC-320, detector TCD, TCD current value 120mA, separation column Active Carbon 30/60, column temperature 95 ℃, carrier gas He 35ml / min)
・ Hydrogen gas: Gas chromatograph (GL Science GC-320, detector TCD, TCD current value 70mA, separation column Molecular sieve 13X, column temperature 40 ℃, carrier gas Ar 25ml / min)
・ Hydrogen sulfide, ammonia: Gas detector tube method (manufactured by Gastec Co., Ltd.)
・ Solubility fraction: Filtrate in GF / B (1μm)

  Table 4 shows the experimental results of two-stage fermentation of simulated raw garbage and food leftovers from hydrogen / methane. In addition, as a comparative experiment, Table 5 shows the results of continuous experiments using simulated raw garbage and leftovers from the cafeteria by one-stage high-temperature methane fermentation. From these results, it is clear that the hydrogen and methane two-stage fermentation method according to the present invention can recover hydrogen gas and methane gas from simulated garbage and food leftovers. It is also clear that organic waste can be processed stably and at high speed. That is, the effect of the solubilization / hydrogen fermentation process based on the present invention is shown.

Example 2
The processing performance of hydrogen / methane two-stage fermentation process for cellulosic solids was investigated.
A series of hydrogen and methane two-stage fermentation experiments were conducted using experimental materials prepared by mixing 10.6 liters of simulated garbage with 20.6 g of toilet paper.
As experimental materials, simulated garbage (Table 1) and toilet paper (Penguin (registered trademark) toilet paper manufactured by Marutomi Paper Co., Ltd.) (hereinafter abbreviated as TP) were used. As a pretreatment of TP, the TP was cut into a suitable size with a scissors, spread so as not to overlap on the stellenless bat, covered with aluminum foil, and dried at 65 ° C. for 1 day or more with a laboratory drier.

The garbage + T.P. raw water used in this experiment was prepared by the following procedure.
-Simulated garbage: Mixing with water = 1: 3 (weight ratio)-Crushing in High mode for about 3 minutes with blender (Model LBC-10 type; Waring)-Dry TP20.6g (cellulose equivalent 18.8) in simulated garbage slurry g) / L (garbage slurry) added ・ Crushing process for about 3 minutes in High mode of the blender

  The experimental equipment is a fully mixed solubilization / hydrogen fermenter (Tokyo Rika Kikai Co., Ltd. Jar Fermenter MBF, total volume 5.0L, effective volume 4.0L, jacket type hot water circulation, hot water circulation device HS-1) and methane. A fermenter (cylindrical type, made of vinyl chloride, total volume 30 L, effective volume 25 L, jacket hot water circulation type) was used. The operating conditions of the experimental apparatus were 55-70 ° C. for the solubilization / hydrogen fermenter, stirring speed 100 r / min, 55 ° C. for the methane fermentation tank, and stirring speed 80 r / min. The raw water input was 2 L / day, the hydraulic residence time was 2-2.5 days for solubilization / hydrogen fermentation, and 13 days for methane fermentation (Table 6). Table 7 shows the raw aqueous state. In this experiment, a part of the overflow liquid from the methane fermentation tank was continuously operated while returning 1.0-2.0 L / day to the solubilization / hydrogen fermentation tank. For the return operation, a roller pump (RP-1000 type, manufactured by Tokyo Rika Kikai Co., Ltd.) was used, and the operation was performed by timer operation divided into four times a day.

  Tables 8 and 9 show the experimental results of two-stage fermentation of hydrogen and methane using simulated food waste + T.P. as experimental materials. From these results, it is clear that according to the hydrogen / methane two-stage fermentation method of the present invention, hydrogen gas and methane gas can be recovered even with organic waste containing a large amount of cellulosic substances. In particular, by carrying out two-stage fermentation while returning a part of the effluent component from the methane fermenter to the solubilization / hydrogen fermentation process, even if most of the organic matter in the raw water is a solid matter such as cellulose, the embodiment It was shown that the treatment can be performed under substantially the same conditions as the hydraulic residence time (solubilization / hydrogen fermentation 2.5-3 days, methane fermentation 12 days) tested in 1. That is, the effect of the solubilization / hydrogen fermentation process based on the present invention is clearly shown. The decomposition rate of the cellulosic substance in the hydrogen / methane two-stage fermentation method according to the present invention was 91% or more (based on the total sugar amount based on the phenol / sulfuric acid method).

Reference example 1
A two-stage fermentation test with hydrogen and methane was conducted using coffee lees as food waste. At this time, in order to promote the hydrogen fermentation reaction in the solubilization / hydrogen fermenter, anaerobic hydrogen-producing microorganisms were introduced into the solubilization / hydrogen fermenter, and the performance effect was also investigated.
In the experiment, the coffee extraction residue (hereinafter referred to as coffee mash) discharged from the factory office is collected, adjusted with tap water to a solids concentration (TS concentration) of 10%, and then milled wet milling The mixture was pulverized with a high-speed mill (high-speed grinder Serendipeater (registered trademark) MKCA6-3 (manufactured by Masuko Sangyo Co., Ltd.)). Table 10 shows the water quality. In the experiment, 10 g of NaHCO ₃ was added to 1 liter of raw water ground to adjust the raw water pH and subjected to continuous experiments. Also, in order to maintain stable methane production activity, Fe / Ni / Co mixed solution [FeCl ₃ (29 g / L), NiCl ₂ · 6H ₂ O (4.4 g / L), CoSO ₄ · 7H as required ₂ O (4.7 g / L)] 1.0 ml was added to 1 L of raw water.

  The experimental equipment is a two-phase partition type solubilization / hydrogen fermentation tank (made of vinyl chloride, total volume 5.5L, effective volume 5.0L, jacketed hot water circulation) and a fully mixed methane fermentation tank (cylindrical type) as shown in FIG. , Made of vinyl chloride, total volume 30L, effective volume 25L, jacket warm water circulation type). The internal configuration of the solubilization / hydrogen fermenter was a solubilized phase in the lower part of the tank and a hydrogen fermented phase in the upper part, and the hydrogen fermentation phase was 40% and the solubilized phase was 60% in volume ratio. The operating conditions of the experimental apparatus were 37-55 ° C for the solubilization / hydrogen fermenter, 55 ° C for the methane fermenter, and a stirring speed of 80 r / min. For the solubilization and agitation of the hydrogen fermenter, the stirring method is based on liquid circulation using a tube pump RP-60 (manufactured by Tokyo Rika Kikai Co., Ltd.). It was done by timer operation twice a day. The raw water input was 1.2 L / day, the hydraulic residence time was about 4 days for solubilization and hydrogen fermentation, and about 20 days for methane fermentation. The raw water input to the solubilization / hydrogen fermenter was injected from the lower part of the side of the fermenter with a tube pump RP-60 type, and the overflow flow from the solubilization / hydrogen fermenter flowed into the methane fermenter. Moreover, continuous operation was carried out while returning a part of the overflow liquid from the methane fermenter 0.6-1.2 L / day to the solubilization / hydrogen fermenter. Use a roller pump (RP-1000 model manufactured by Tokyo Rika Kikai Co., Ltd.) for the return operation. Divide into 4 times a day, solubilize by timer operation, and inject into the hydrogen fermenter from the bottom of the fermenter in an upward flow manner. .

Furthermore, in this experiment, an anaerobic hydrogen-producing microorganism Clostridium butyricum SC-E1 strain (Fukui No. FERM P-14790) was introduced to promote the hydrogen fermentation reaction. For the introduction of the SC-E1 strain, adjust the centrifugal concentration of the culture solution (3,000r / min, 5min) and use a roller pump (RP-1000, manufactured by Tokyo Rika Kikai Co., Ltd.) four times a day. It was divided into two, and it was introduced into the solubilization / hydrogen fermenter by the timer operation from the upper part of the fermenter in a downward flow manner. The amount of introduced bacterial solution was 20-40 mL / day. SC-E1 strain was prepared using 1.0 g of inorganic salt solution and 5.0 g glucose; Polypeptone (Nippon Pharmaceutical Co., Ltd.) 5.0 g; Yeast extract (Difco) 0.1 g; l-cysteine · HCl · H ₂ O 0.5 g; Na ₂ S · 9H ₂ O 0.5 g; A medium for hydrogen fermentation adjusted to resazurin 1.0 was used (pH 6.7-6.8). The composition of the inorganic salts is as follows. (NH ₄ ) ₂ SO ₄ 3.0 g / L; KH ₂ PO ₄ 0.2 g / L; K ₂ HPO ₄ 1.6 g / L; MgSO ₄ 7H ₂ O 0.2 / L g; NaCl 0.1 g / L; CaCl ₂ 2H ₂ O 0.02g / L; FeSO ₄・ 7H ₂ O 0.01g / L; MnCl ₂・ 4H ₂ O 0.5mg / L; l-cysteine ・ HCl ・ H ₂ O 0.25g / L; Na ₂ S ・ 9H ₂ O 0.25 g / L; Resazurin 1 mg / L; pH 7.0. The SC-E1 strain is cultured using a jar fermenter MBF manufactured by Tokyo Rika Kikai Co., Ltd. (total volume 5.0L, effective volume 4.0L, jacketed hot water circulation), and the fermenter gas phase at the start of the culture is 100% nitrogen gas The hydrogen fermentation temperature was 37 ° C. and the HRT was 40 h.

  Table 11 shows the experimental results of two-stage hydrogen / methane fermentation using coffee grounds as an experimental material. According to the hydrogen / methane two-stage fermentation method of the present invention, hydrogen gas and methane gas can be recovered even with hardly decomposable organic waste, and the treatment effect of the solubilization / hydrogen fermentation process was shown. In particular, hydrogen fermentation was promoted by introducing anaerobic hydrogen-producing microorganisms into the solubilization / hydrogen fermenter, and stable treatment was possible without accumulating organic acids even in the methane fermentation process. In addition, the VS decomposition rate of coffee koji in the hydrogen / methane two-stage fermentation method according to the present invention was 59%.

  The organic waste anaerobic treatment method of the present invention can easily solubilize and reduce the molecular weight of organic solids in a short time, so that sewage sludge, surplus sludge, livestock manure, garbage, It is particularly useful in environmental protection industries such as organic waste processing industries such as food manufacturing waste.

The block diagram which shows one Embodiment of the hydrogen and methane two-stage fermentation apparatus of the organic waste concerning this invention. The block diagram which shows embodiment of the solubilization and hydrogen fermentation apparatus of the organic waste which corresponds to the reference example of this invention. Schematic which shows another embodiment of the solubilization and hydrogen fermentation apparatus of the organic waste concerning this invention. Schematic which shows 1st embodiment of the laboratory experiment using the hydrogen and methane two-stage fermentation apparatus of the organic waste concerning this invention. Schematic which shows 2nd embodiment of the laboratory experiment using the hydrogen and methane two-stage fermentation apparatus of the organic waste concerning the reference example of this invention. Schematic which shows embodiment of the outdoor experiment using the hydrogen and methane two-stage fermentation apparatus of the organic waste concerning this invention. The material balance of the hydrogen / methane two-stage fermentation process is shown. The block diagram which shows the conventional organic waste methane fermentation.

1 Solubilization / hydrogen fermentation tank (solubilization / hydrogen fermentation reactor)
1A Solubilization fermentation section 1B Hydrogen fermentation section 2 Methane fermentation tank (methane fermentation reactor)
2A High-temperature methane fermentation tank 3 Physicochemical reactor 4 Garbage 4A Raw water 5 Easy degradable waste 6 Refractory waste 7 Organic waste 8 Diluted water 9 Biogas 10 Fermentation residue 11 Supernatant liquid 12 Anaerobic sludge 13 Sludge Liquid 14 Solid 15 Hydrogen 16 Methane 17 Pretreatment tank 18 Raw material storage tank 19 Solubilization / hydrogen fermentation reactor 20 Completely mixed methane fermentation reactor 21 Fermentation residue storage tank 22 Hydrogen tank 23 Methane tank 24, 25 Desulfurization tower

Claims (2)

  In the waste organic waste treatment mainly including carbohydrate waste or the waste organic waste treatment containing cellulosic solids, it is refined and homogenized in the pretreatment step and the concentration is VS 5 Combines anaerobic solubilization and hydrogen fermentation of a fully mixed type that is processed in a biological reaction of 30 to 70 ° C., pH 5 to 8.5, hydraulic residence time 2 to 3 days, with respect to 15 wt% of the raw material. Performing a two-stage fermentation method consisting of a fully mixed methane fermentation process in the subsequent stage, and returning a part of the effluent components from the methane fermentation process to the process having both anaerobic solubilization and hydrogen fermentation. Biologically anaerobic treatment method to recover hydrogen and methane.   In a garbage-based organic waste treatment apparatus mainly comprising a sugar-based waste or a garbage-based organic waste treatment apparatus containing cellulosic solids, the concentration is reduced to VS 5 while being refined and homogenized in a pretreatment process. A raw material tank in which raw materials adjusted to ˜15 wt% are put together, and anaerobic solubilization and hydrogen fermentation treated in a biological reaction at 30 to 70 ° C., pH 5 to 8.5, hydraulic residence time 2 to 3 days are combined in the previous stage An apparatus for performing a two-stage fermentation method comprising a fully mixed type anaerobic solubilization / hydrogen fermenter that performs a process, and a methane fermenter that performs a fully mixed type methane fermentation process in the subsequent stage. Biologically, hydrogen is provided with a return pipe for returning a part of the outflow component from the tank to the anaerobic solubilization / hydrogen fermentation tank for performing a process having both anaerobic solubilization and hydrogen fermentation. Anaerobic treatment to recover methane Apparatus.

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