WO2015019382A1 - Two-stage methane gas generating system having front end aggregation step - Google Patents

Abstract

[Problem] To achieve an easily operated treatment system for treatment of organic waste with a high water content such as sewage and livestock waste, that has little treated water and a low residual environmental impact, is efficient with a high yield for methane gas generation, has comparatively small equipment, and has inexpensive construction costs. [Solution] A two-stage methane gas generating system has an aggregation step disposed in a preliminary stage of a fermentation step formed from a solubilization tank in which sludge is solubilized by aerobic fermentation and a methane generating tank in which the solubilized sludge is made to undergo anaerobic methane fermentation, and the water content of the sludge is made 70 wt% or less so that a drying treatment can be carried out.

Description

Two-stage methane gas generation system with pre-flocculation process

The present invention relates to a system for processing organic waste having a high water content such as sewage and livestock excrement. In particular, the present invention relates to a system that efficiently obtains methane gas by separating raw material biomass into sludge and treated water by a coagulation process, and then methanating the sludge portion in a dry manner.

As shown in the process diagram of FIG. 3, conventionally, the raw material biomass is generally first treated by the activated sludge treatment apparatus 6, and the remaining sludge is treated by a method such as fermentation. The activated sludge treatment apparatus 6 used in this requires a large aeration tank 62 and a sedimentation basin 63, and requires a large amount of power for aeration, which is a problem in terms of initial construction cost, operation cost, operating energy, and site area. There is.

Moreover, the treated water 102 of the activated sludge treatment apparatus 6 and the treated water at the time of solid-liquid separation of the concentrated sludge 104 have high BOD and COD, and there is a problem that advanced water treatment is necessary.

After the concentrated sludge 104 discharged from the activated sludge method treatment apparatus 6 passes through the coagulation tank 81 and passes through the solid-liquid separation / dehydration apparatus 82, it becomes a sludge cake 106 and is sent to the next stage process. In the activated sludge method, the amount of sludge increases due to assimilation of microorganisms, but on the other hand, there is also a phenomenon that the amount of sludge decreases due to the generation of carbon dioxide and water by the decomposition of microorganisms. In the conventional treatment, the production load of compost / methane 111 by the fermentation process 91 of the next stage, the production of incinerated ash / charcoal 112 by the incineration / carbonization treatment 92, and the production of the soil conditioner 113 by the drying treatment 93 are reduced. Therefore, the amount of sludge is aimed at minimization. For example, in an agricultural settlement drainage facility in western Akeno, Chikusei City, Ibaraki Prefecture, the BOD flowing into the activated sludge treatment apparatus is 110 mg / l and SS is 64 mg / l (January 2013). In ordinary household wastewater, 35 to 45% of the removed BOD is sludge (Non-patent Document 1). If 40% of the removed BOD is sludge, assuming that the SS is surplus sludge, 110 × 0.4 = 44 mg / l SS is surplus sludge. Actually, since there is a contribution of dissolved components other than SS in the BOD portion, it is considered that at most about 2/3 of the organic matter contributing to the original BOD has become sludge.

This indicates that there is a problem that resources are wasted if sludge is regarded as a resource. Therefore, methods other than the activated sludge method have been proposed in terms of effective use of resources. For example, the generated sludge can be methanated by anaerobic fermentation. In that case, the generated methane gas can be used as fuel. Furthermore, the fermentation residue can be used as a fertilizer. In this case, the larger the amount of sludge, the larger the amount of methane gas that can be obtained.

However, there is another problem with the aim of producing methane gas. An anaerobic environment is required for methane fermentation, but in most cases, it is realized by a wet method (or a water seal type) in which raw material biomass is immersed in a large amount of water to block oxygen. As a result, a mixture of fermentation residue and water is obtained as a product of anaerobic fermentation.

It would be advantageous if there were conditions that could be used as liquid fertilizer. However, in an environment where there is no use for liquid fertilizer, there is a problem that solid-liquid separation operation and water treatment of this mixture are further required.

In order to avoid this, there was a dry method in which the moisture content of the raw material biomass was reduced and the water content was reduced to 70 wt% or less instead of being wet. The inventors of the present application have already placed an aerobic fermentation drying tank immediately before the anaerobic fermentation tank as a means for drying to reduce the moisture of the raw material biomass, and further, the residue of the anaerobic fermentation process is placed in the aerobic fermentation drying tank. A recycling method was proposed (Patent Document 1).

According to this method, since the moisture content of the raw material biomass input to the anaerobic fermentation process is reduced to 70 wt% or less and dry anaerobic fermentation is performed, the throughput can be significantly reduced. For example, when the raw material biomass having a moisture content of 97 wt% is set to a moisture content of 70 wt%, the volume reduction rate and the weight loss rate are about 1/10. In addition, methane yield (methane production per unit raw material biomass) is increased by recycling the residue in the anaerobic fermentation process.

However, the problem that the energy which raw material biomass has consumed for the drying process which uses the aerobic fermentation heat of raw material biomass remained.

In another example, as a method of combining coagulation sedimentation and fermentation, an organic wastewater containing organic solids was separated in this coagulation sedimentation tank by solid-liquid separation treatment by adding an inorganic coagulant. Proposed a processing system comprising an acid generation tank that causes an acid fermentation reaction of organic components contained in the processing liquid, and an anaerobic processing tank that anaerobically treats the processing liquid processed in the acid generation tank (Patent Document 2).

In this example, in order to remove fine organic solids such as suspended solids contained in organic wastewater by coagulating sedimentation in the coagulation sedimentation tank, passing through the anaerobic treatment tank in the latter stage is not However, the quality of the treated water is improved, but the purpose is not to recycle the organic solids that have been coagulated and precipitated, but to improve the efficiency of the treatment of the anaerobic treated water in the subsequent stage.

In general, in the organic waste treatment, maximization of energy conversion of sludge resources has not been realized.

By the way, the conventional coagulation method using the coagulant has the following problems. In other words, since inorganic flocculants such as aluminum sulfate and iron chloride are used in combination with polymer flocculants, and natural or artificial zeolite is added, multiple raw material sources and production processes There have been problems such as complication, complication process, increase in agglomeration cost, low tendency to dewater, and adverse effect of flocculant on the environment. Further, the BOD of the supernatant liquid after aggregation does not sufficiently decrease, and it is necessary to add advanced water treatment in order to discharge it outside the treatment facility.

PCT / JP2011 / 002270 JP 2005-125202 A

The problem to be solved by the present invention is that in the treatment of organic waste with a high water content such as sewage and livestock excrement, the environmental impact of the generated treated water and products (residues) is low and the yield of raw material sludge that can be converted to energy is reduced. By increasing the number, it is possible to realize a processing system with high yield of methane gas generation, relatively small equipment, low construction cost, and easy operation.

The present invention is a system for generating and recovering methane gas by treating raw water biomass such as sewage and livestock excreta, and mixing and aggregating the flocculant with the raw material biomass, so that the solid floating in the raw material biomass A coagulating sedimentation tank to obtain sludge by coagulating and sedimenting the product and lysate, optionally with adsorption, ion exchange or adsorption and ion exchange;
A solubilization tank that is mechanically sealed from the outside air, includes a stirring means, a hot air generation means, and an aeration means, and solubilizes the precipitated sludge by aerobic fermentation;
A methane production tank that is mechanically sealed from the outside air, provided with stirring means and heat exchange means, and anaerobic methane fermentation of the solubilized sludge;
A two-stage methane gas generation system comprising a transfer device for connecting the coagulation sedimentation tank, the solubilization tank, and the methane generation tank in the order described, and transferring the sludge between the tanks. is there.

The basic idea of the present invention is that in a two-stage methane gas generation apparatus in which a methane generation tank that performs anaerobic methane fermentation is connected to the next stage of a solubilization tank that performs aerobic fermentation, It is arranged. An appropriate dehydrator can be added to the coagulation sedimentation tank.

Since the moisture content of the raw material biomass can be lowered by the coagulation sedimentation tank and the dehydrator, the raw material biomass is reduced in volume and processed in the front and rear fermentation tanks. Therefore, compared with the case where the volume is reduced by heating and drying, the required energy can be reduced and the energy efficiency is improved.

The flocculant of the present invention is a flocculant containing a multifunctional inorganic carbide as a main component in order to solve the conventional problems. In addition to the aggregating function, the multi-function has the ability as a fungus bed to grow and propagate fermented fungi on the surface even in the fermentation process of separated sludge, adjust the pH of the fermentation process, anaerobic It refers to possessing multiple functions that suppress the generation of hydrogen sulfide generated in methane fermentation and that the final residue can be used for land improvement.

When a multifunctional inorganic carbide is used as a flocculant, the cost and the coagulation sedimentation rate are the same as those of conventional flocculants, but the coagulation efficiency is excellent due to the effects of adsorption and ion exchange functions. At the same time, the environmental load is low and the dehydration tendency is excellent. The process of attaching sludge to the periphery of the multifunctional inorganic carbide by an operation called coagulation sedimentation in advance realizes further increase in efficiency of the fermentation process.

By adding multifunctional inorganic carbide to the solubilization tank that performs the aerobic fermentation of the previous stage in the two-stage fermentation process, the solubilization rate by aerobic fermentation is increased, and the acidity that becomes an inhibitory factor for the subsequent anaerobic methane fermentation Since the conditions are relaxed, the rate of methane production by anaerobic methane fermentation increases.

In addition, ammonia, which is an anaerobic fermentation inhibitor, can be removed in the acid production step for producing an organic acid following the solubilization step by aerobic fermentation (here, a low molecular weight process involving hydrolysis). Fermentation can be accelerated (Non-patent Document 2).

In addition, it has been demonstrated that the hydrolysis and acid generation processes in solubilization by aerobic fermentation in the previous stage proceed, and that the organic acids produced in the latter stage are used and consumed for methane fermentation. It has been shown by experiments (Non-Patent Document 3).

In addition, on the surface of the multifunctional inorganic carbide referred to in the present invention, the presence of microorganisms exhibiting a branched cell morphology found in the Cellulomones genus and the like that secrete cellulolytic enzymes can be increased by the SEM microscope. Since it was confirmed from the measurement experiment, when the multifunctional inorganic carbide is introduced into the aerobic solubilization fermentation process, the multifunctional inorganic carbide increases the solubilization efficiency by the aerobic fermentation (Non-patent Document 4).

In addition, as shown in the pH column of Table 1, the multifunctional inorganic carbide suppresses a decrease in pH due to organic acid even in methane production by anaerobic methane fermentation at the later stage due to the alkaline maintenance function of the surface and inside. Reduces the inhibition of the activity of fermenting bacteria. Furthermore, the multifunctional inorganic carbide is generated with anaerobic fermentation and suppresses hydrogen sulfide that causes device corrosion. In order to enhance these functions, the multifunctional inorganic carbide can be additionally supplied in the solubilization tank and / or the methane production tank.

The multifunctional inorganic carbide added as a coagulant in the coagulation settling tank can of course perform these functions other than coagulation in the subsequent fermentation tank, but is additionally added in the solubilization tank and / or methane production tank as necessary. Thus, a desired function can be enhanced.

In the system of the present invention, a part of the residue remaining in the methane production tank can be recycled to the solubilization tank. This is to return part or all of the sludge from the methane production tank to the solubilization tank as appropriate, and to further ferment the unfermented sludge.

As the structure of the solubilization tank and the methane production tank, a horizontal drum type is desirable. In the structure using the rotating stirring blade, the torque for rotation is large due to the viscosity of the raw biomass having a low water content, so that the mechanical load on the rotating blade is large and the power consumption for driving is also large. There are also raw material biomass that cannot be stirred by rotating blades.

On the other hand, in the horizontal drum type, the center fixed shaft is fixed, and the body portion is rotatably supported. As the drum fermenter rotates, the internal raw material biomass is reversed, and the drum rotates. In addition, there are few parts that cannot be stirred due to the effect of the stirring blades inside.

In processing raw biomass, promote the recycling of produced sludge without using the activated sludge method and advanced water treatment. The moisture content of the raw material biomass is reduced not by thermal drying that consumes energy but by agglomeration and dehydration processes. For this reason, the fermentation time in the front and rear stages shortens the processing time. For these reasons, a compact methane gas generation system with a high yield of methane gas can be realized.

Furthermore, if a horizontal drum-type structure is used for the solubilization tank that performs the aerobic fermentation in the previous stage, since the raw material biomass is reversed and stirred by the rotation of the solubilization tank itself, solubilization is high. Speed can be increased. Since the stirring efficiency is also high in the latter methane generation tank, the methane gas generation rate can be increased.

In addition, in the solubilization tank that performs the aerobic fermentation of the previous stage, the addition of multifunctional inorganic carbides increases the solubilization rate and relaxes the acidic conditions that are the inhibiting factors of the subsequent anaerobic methane fermentation, so the production of methane gas Increases speed. Furthermore, the corrosive hydrogen sulfide generated with methane generation is suppressed.

Process diagram of two-stage methane gas generation system with pre-flocculation process Conceptual diagram of horizontal drum type fermenter Process diagram of raw water biomass treatment system using activated sludge method

Hereinafter, a two-stage methane gas generation system having a pre-aggregation process according to the present invention will be described with reference to examples.

FIG. 1 is a process diagram of a two-stage methane gas generation system having a pre-aggregation process according to the present invention. A process flow will be described with reference to FIG. The raw material biomass, which is organic waste with a high water content such as sewage and livestock excrement received by the methane gas generation system 1, passes through the raw material inlet 51 and is the first stage of the coagulation / dehydration apparatus 20. to go into.

Here, the flocculant containing a multifunctional inorganic carbide is mixed and stirred in the raw material biomass, and the solid suspended matter and the dissolved matter in the raw material biomass are coagulated and precipitated. The coagulated and settled sludge is extracted from the lower side of the coagulation sedimentation tank 21, passed through the sedimentation sludge transfer pump 23, and charged into the dehydrator 22. As the dehydrator 22, an appropriate method such as a centrifugal dehydrator method or a belt press method can be selected. The treated water after the coagulation sedimentation is discarded from the treated water pipe 25 without performing a special treatment. Or you may put the simple process process which is not illustrated.

The sludge is dehydrated by the dehydrator 22 and the water content becomes 70 wt% or less. A drying apparatus can be disposed after the dehydrator 22 to further reduce the moisture content of the raw material biomass to be introduced into the solubilization tank 31. The entire amount of treated water generated by dehydration is returned to the coagulation sedimentation tank 21 through the return water pipe 24. The remaining sludge after dehydration is sent to the solubilization tank 31 via the transfer device 52.

The solubilization tank 31 is mechanically sealed and includes stirring means, hot air generating means, and aeration means. Hot air generated by hot air generating means (not shown in FIG. 1) can be blown into the tank of the solubilization tank 31 by the ventilation means to keep the inside of the tank at a desired temperature. When inoculated bacteria to be aerobically fermented that have been preheated in the solubilization tank 31, the transferred sludge is agitated by agitation means to come into contact with oxygen in the air and aerobic fermentation at a desired temperature. Solubilization proceeds. Further, the odor generated with the fermentation can be deodorized by the exhaust means and the deodorizing means (not shown in FIG. 1) before being diffused to the atmosphere.

The reason why the solubilization tank 31 is mechanically sealed is that the heat energy in the tank is not dissipated and used for heating the methane generation tank in the next stage, and the generated ammonia odor is dissipated. This is to prevent it from happening.

In the sludge that has been aerobically fermented in the solubilization tank 31, the high-molecular polysaccharides, fats, and proteins contained therein are decomposed into low-molecular monosaccharides, fatty acids, and amino acids, respectively. Furthermore, these single molecules are rapidly decomposed into organic acids. This is sent to the methane production tank 41 through the transfer device 53.

The methane production tank 41 is mechanically sealed and includes stirring means and heat exchange means. The heat exchange means guides the exhaust heat of the solubilization tank 31 to the methane generation tank 41 and warms the sludge as the contents. The sludge is agitated in a timely manner by agitation means, and anaerobic methane fermentation proceeds, and the produced methane is easily released from the sludge. The reason for mechanically sealing the methane generation tank 41 is to maintain the anaerobic environment necessary for methane generation, and to recover the methane gas generated through the anaerobic methane fermentation of the sludge through the gas pipe 13 and accumulate it in the gas tank 11. It is. The accumulated gas is used as fuel for hot air generating means, a power generation gas engine, and the like.

The portion that becomes a residue in the methane generation tank 41 is recycled to the solubilization tank 31 through a transfer device 55 within a necessary range. Since the residue of the methane production tank 41 includes a portion where the methane fermentation has not been completed, the residue may be recycled to the inlet of the methane production tank 41 through the transfer device 55.

Here, the flocculant used in the coagulation sedimentation tank 21 placed at the beginning of the process will be described. The flocculant is a multifunctional inorganic carbide or a multifunctional inorganic carbide added with an existing flocculant. Multifunctional inorganic carbides, as shown in Table 1 and Table 2, refer to those having raw materials, production methods and functions different from those of general charcoal and activated carbon.

Specifically, as shown in Table 1, the multifunctional inorganic carbide is produced by firing the raw material at a high temperature that is about 200 ° C. higher than that for producing general coal used as a normal fuel, blocking oxygen at all. Therefore, it is almost completely made of carbon, the specific gravity is very light as 0.28 to 0.3, the specific surface area is 300 m2 / g or more, which is larger than 50 m2 / g of ordinary steam coal, and is particularly conductive. There is.

On the other hand, as shown in Table 2, activated carbon requires a two-stage manufacturing process in which the material is steamed at 200 to 600 ° C. and then activated at a high temperature of 600 to 1000 ° C. Since it can be manufactured by only one-stage baking process, the process is simple and the required energy can be reduced. In addition, multifunctional inorganic carbides are weakly alkaline and advantageous for fermentation, whereas activated carbon is strongly alkaline and microorganisms such as fermenting bacteria stop their activities or die. In addition, activated carbon is produced from wood, coconut shells, coal, etc. as raw materials, but it is general biomass that can be produced from multifunctional inorganic carbides, for example, from sludge residues generated after sewage treatment. It will be a countermeasure.

As a specific example of the multifunctional inorganic carbide, high-performance inorganic charcoal manufactured by Venture Visor Pro Co., Ltd. is used as a powder, and a portion having a particle size range of 250 to 600 μm is selected with a metal sieve.

This multifunctional inorganic carbide was subjected to an experiment on the coagulation function according to the following method. (1) Multifunctional inorganic carbides that have been pulverized in advance in a mortar and arranged to a particle size of 250 to 600 microns using a metal sieve. (2) The target wastewater used is a dilution of concentrated sludge produced in an activated sludge aeration tank at a domestic wastewater treatment plant in Chikusei City, Ibaraki Prefecture. (3) Using 0.1 g per liter of multifunctional inorganic carbide as a flocculant, stirring with a stirring motor, transferring to a graduated cylinder, and determining the coagulation sedimentation rate from the temporal change in the position of the supernatant liquid and sludge layer. taking measurement. (4) The sludge after a certain time is filtered, and the water content of the sludge after filtration is measured. (5) The COD of the supernatant is measured by a pack test.

In Table 3, when multifunctional inorganic carbide, natural zeolite, and commercially available inorganic flocculant Pulclean (trade name manufactured by Sies Chemical Industry Co., Ltd.) are used alone as flocculants, they are natural for multifunctional inorganic carbides. The agglomeration experiment results when using a flocculant added with zeolite and aluminum sulfide are shown. Stirring speeds other than Pulclean were 650 rpm and the stirring time was 5 minutes. For Pulclean, stirring was performed at 650 rpm for 2.5 minutes and then at 150 rpm for 2.5 minutes. After stirring, the mixture was transferred to a 1000 cc graduated cylinder, and the sedimentation rate was measured by the time change of the height of the upper surface of the coagulated sludge. Table 3 shows the measurement results of the volume below the upper surface of the coagulated sludge.

From the sedimentation rate experimental results shown in Table 3, it was shown that the multifunctional inorganic carbide has almost the same aggregating function as that of the natural zeolite, Parklein, which is a commercially available flocculant. This is because the multifunctional inorganic carbide has a positive charge and is electrically conductive, so that the negative charge of the sludge fine particles is neutralized and the solid suspended matter and dissolved matter are adsorbed, ion-exchanged or adsorbed and ionized. This is considered to promote aggregation in some cases with exchange. The gravity dehydration tendency of multifunctional inorganic carbides was not inferior to that of commercially available flocculants such as natural zeolite and parklean.

Next, Table 4 shows a comparison between the multifunctional inorganic carbide and Pulclean regarding the BOD of the supernatant liquid after the coagulation sedimentation by the above experiment. The measurement of BOD of the supernatant was entrusted to Oosumi Co., Ltd. This measurement showed that the BOD of the supernatant liquid was low when the multifunctional inorganic carbide was used. The BOD is set to 160 mg / l or less for the industrial wastewater (water discharged to areas other than the sea and lakes), and is set by the Ministry of the Environment. Therefore, the supernatant liquid of the coagulation sedimentation tank 21 in the present invention has a sufficiently low BOD due to the coagulation ability of the multifunctional inorganic carbide, and can be discharged almost as it is without any other treatment.

According to the above experiment, as shown in Table 4, the BOD removal rate of the supernatant when the multifunctional inorganic carbide is used as the flocculant is 99.6% or more. In the domestic wastewater treatment plant in Chikusei City, Ibaraki Prefecture, the inflow water flowing into the activated sludge process, that is, the BOD of the raw wastewater is about 110 ppm in January 2013. Since the BOD of the discharged water subjected to the advanced water treatment after the activated sludge method is 0.9 ppm, the BOD removal rate is about 99.2%. If the multifunctional inorganic carbide is used as a flocculant for the influent water, and it has the same removal rate of 99.6% for the inflow water, the BOD of the supernatant after the coagulation sedimentation is It can be suppressed to 0.5 ppm or less. This indicates that advanced water treatment is not always necessary after coagulation sedimentation.

In the activated sludge process, organic matter undergoes adsorption and assimilation by an aerobic microorganism group, and then flocks (particles become coarse) to generate sludge. Therefore, the treatment takes a relatively long time. On the other hand, in the coagulation sedimentation by the multifunctional inorganic carbide, the aggregation occurs due to the physicochemical interaction, so the aggregation rate is high, and the precipitation rate is also large because the floculated particles are large. In addition, the running cost of the flocculant is lower than the electricity cost for aeration in the activated sludge method. Furthermore, since most of the aggregated sludge is a raw material for recycling, the present invention is superior to the case using the activated sludge method from the viewpoint of recycling.

The following conclusions were obtained from the above experiment. Compared with the existing flocculant, the multifunctional inorganic carbide showed the same effect in other flocculating functions, and showed an excellent effect in removing BOD. Therefore, it was found that the disadvantage of the existing multi-component flocculant can be improved by using the multifunctional inorganic carbide alone.

In addition, in a solubilization tank and / or a methane generation tank, a desired function such as maintaining alkalinity or suppressing generation of hydrogen sulfide is enhanced by additionally supplying a multifunctional inorganic carbide as necessary. You can also.

FIG. 2 is a conceptual diagram of a horizontal drum type fermenter. In the two-stage methane gas production system having the pre-flocculation process according to the present invention, it is desirable that the solubilization tank and the methane production tank constituting the two-stage fermentation tank are of a horizontal drum type. This is because if the moisture content is 70 wt% or less in order to achieve a dry process, the sludge has a viscosity that does not flow, so that a large stirring torque is required in an apparatus having rotating stirring blades.

As can be seen in FIG. 2, the solubilization tank 31 and the methane generation tank 41 have the same basic structure except that the length of the horizontal drum is different. The same reference numerals in both tanks denote the same numbers, and the subscript “a” indicates that it is a part of the solubilization tank 31, and the subscript “b” indicates a part of the methane generation tank 41. Indicates that there is. In the following description and drawings, subscripts may be omitted when common to both tanks.

In both the solubilization tank 31 and the methane generation tank 41, a cylindrical drum body 121 is rotatably supported by a front chamber 122 and a rear chamber 123 fixed on the base 120.

A rotary sealing mechanism is provided between the fixed front chamber 122 and rear chamber 123 and the drum body 121, and is mechanically sealed from the outside air. Moreover, the solubilization tank 31 is provided with a stirring means, a hot air generation means, and an aeration means, and the methane generation tank 41 is provided with a stirring means and a heat exchange means.

Both tanks are provided with a center fixed shaft 124 fixedly supported by the front chamber 122 and the rear chamber 123.

Both tanks are provided with shutters that block airflow between the two tanks, and are connected in the order shown in FIG. 1 by a transfer device 53 sealed from the outside air. Further, at the outlet of the methane production tank 41, a cutting machine 54 for discharging the fermentation residue is installed, from which the fermentation residue is recycled to the solubilization tank 31.
In FIG. 2, illustration of a gas holder for storing the generated methane gas and other attached devices is omitted.

Both tanks are equipped with three types of paddle-shaped stirring blades as stirring means. In FIG. 2, only one symbol is attached to the same stirring blade to avoid the drawing from becoming complicated.
A plurality of transfer blades 126, which are first stirring blades, are arranged in a spiral pattern on the inner wall of the tank and are arranged upright, and each blade moves the contents in the tank outlet direction as the tank rotates (see FIG. 2) Proceed and transfer toward the right).

The reversing blades 127, which are the second stirring blades, are also arranged in a row parallel to the center fixed shaft 124 at each of the upper, lower, left and right positions of the inner wall of the tank, and each blade is accompanied by the rotation of the tank. Then scoop up the contents in the direction of rotation and invert the contents.

The fixed blade 125, which is the third stirring blade, is attached to the center fixed shaft 124 in a cross shape. The fixed blade 125 generates a force for transferring the contents in the front direction (left direction in FIG. 2). This stirs the contents against the driving force by the transfer vanes 126.

Except for the above points, the second embodiment is the same as the first embodiment.

According to the present embodiment, since the solubilization tank 31 and the methane generation tank 41 have basically the same structure, the cost for manufacturing and maintaining the apparatus is low.
By making the solubilization tank 31 and the methane generation tank 41 into a horizontal drum type, the contents of the tank can be agitated with small power, and there are few parts that are not agitated.

Inside the solubilization tank 31, the contact between the hot air blown and the contents of the tank is improved by the stirring means, and the aerobic fermentation proceeds quickly. Inside the methane production tank 41, the biomass mass in the course of anaerobic fermentation is crushed by the stirring means, and the emission of methane gas from the sludge is improved.

The present invention contributes to the development of various industries that discharge raw material biomass, in particular, many industries such as agriculture, fisheries, livestock, food processing, and sales distribution, and can contribute to the activities of local governments that handle garbage.

DESCRIPTION OF SYMBOLS 1 Methane gas production system 11 Gas tank 12 Horizontal drum type fermenter 120a, 120b Base 121a, 121b Body part 122a, 122b Front chamber 123a, 123b Rear chamber 124a, 124b Center fixed shaft 125a, 125b Fixed blade 126a, 126b Transfer blade 127a, 127b Inverting blade 13 Gas pipe 20 Coagulation / dehydration apparatus 21 Coagulation sedimentation tank 22 Dehydrator 23 Precipitation sludge transfer pump 24 Return water pipe 25 Treated water pipe 31 Solubilization tank 41 Methane generation tank 51 Raw material inlet 52 Transfer apparatus 53 Transfer apparatus 54 Cutting Unloader 55 Transfer device 6 Activated sludge treatment device 61 Initial sedimentation basin 62 Aeration tank 63 Sedimentation basin 7 Advanced water treatment 81 Coagulation tank 82 Solid-liquid separation / dehydration device 91 Fermentation treatment 92 Incineration / carbonization treatment 93 Drying treatment 101 Raw water 102 Treatment Water 103 Highly treated water 104 Concentrated sludge 105 Return sludge 106 Sludge cake 111 Compost, methane 112 Incinerated ash, charcoal 113 Soil conditioner

Claims (6)

1. A system that generates and recovers methane gas by processing high moisture content raw material biomass such as sewage and livestock excreta,
   A flocculant that mixes and stirs the raw material biomass with solid flocculent and dissolved matter in the raw material biomass, adsorbs, ion-exchanges or adsorbs and ion-exchanges in some cases, and coagulates and precipitates to obtain sludge ,
   A solubilization tank that is mechanically sealed from the outside air, includes a stirring means, a hot air generation means, and an aeration means, and solubilizes the precipitated sludge by aerobic fermentation;
   A methane production tank that is mechanically sealed from the outside air, provided with stirring means and heat exchange means, and anaerobic methane fermentation of the solubilized sludge;
   2 having a pre-flocculation step characterized in that the coagulation sedimentation tank, the solubilization tank and the methane generation tank are connected in the order described, and a transfer device for transferring the sludge is provided between the tanks. Stage type methane gas generation system.
2. The two-stage methane gas generation system having the pre-aggregation step according to claim 1, wherein the flocculant contains a multifunctional inorganic carbide.
3. A two-stage methane gas generation system having a pre-aggregation step according to claim 1, wherein the solubilization tank and / or the methane generation tank is additionally supplied with a multifunctional inorganic carbide. Methane gas generation system.
4. A two-stage methane gas generation system having a pre-aggregation step according to claim 1, wherein a part of sludge generated in the methane generation tank is recycled to the solubilization tank and / or the methane generation tank. Characteristic two-stage methane gas generation system.
5. A two-stage methane gas generation system having a pre-aggregation process according to claim 1, wherein the solubilization tank and the methane generation tank have a center fixed shaft fixed and a trunk portion rotatably supported. A two-stage methane gas generation system characterized by being a horizontal drum type tank mechanically sealed from outside air.
6. A two-stage methane gas generation system having a pre-flocculation step according to claim 1, further comprising a dehydrator for dewatering sludge, and after dewatering the concentrated sludge in the condensation sedimentation tank, to the solubilization tank A two-stage methane gas generator characterized by transporting.

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