JP2006007121A - Method and apparatus for treating organic waste - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a method and an apparatus for treating organic waste, in each of which a decomposition rate of a cell membrane is high and efficient treatment results can be obtained with respect to the thrown energy. <P>SOLUTION: This method for treating organic waste comprises an impact hydraulic treatment step of generating impact hydraulic pressure in organic waste to fracture the cell membrane of a microbe before a dehydration step. When this method for treating organic waste comprises a methane fermentation step, the impact hydraulic treatment step is carried out before the methane fermentation step. When the methane fermentation step is carried out by two steps of an acid fermentation step and a methanation step, the impact hydraulic treatment step is carried out before and after the acid fermentation step. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method and apparatus for treating organic waste.

The treatment of organic waste such as feces, livestock urine, sewage sludge, septic tank sludge, combined septic tank sludge, agricultural sludge, dredging and various biomass is a major social problem in recent years. Various proposals have been made.
Many treatment methods for such organic waste containing a lot of water include a dehydration step and a methane fermentation step. Methane gas is widely used because it can recover energy from organic waste and can reduce the amount of incineration and landfill.
However, organic waste contains a large amount of animal and plant cells and microbial cells, and these cells are covered with a very persistent and strong cell membrane. For this reason, even if dehydration is performed, these cell membranes cannot be destroyed, so that intracellular moisture is maintained as it is, and it is difficult to reduce the moisture content. In addition, even when performing methane fermentation, since it is covered with the cell membrane, decomposition at the cellular level does not proceed, and fermentation of intracellular materials cannot be performed, resulting in a small amount of gas generation, There was a problem that a large amount of residue was generated.

As a solution to such problems, for example, sludge generated in wastewater treatment, after sludge decomposition in the sludge decomposition process, ultrasonic treatment in the ultrasonic treatment process, and the sludge treatment method of treating in the methane fermentation process Has been proposed (see Patent Document 1). The thing of this patent document 1 improves the decomposition efficiency of sludge by performing an ultrasonic treatment to what decomposed | disassembled in the sludge decomposition process.
In addition, ozone treatment, heat treatment, and pulverization treatment using a ball mill have been studied as methods for improving sludge decomposition efficiency.
JP 2002-336898 A

  However, none of the above conventional methods have a cell membrane degradation rate and a treatment effect commensurate with the input energy cannot be obtained.

  The present invention has been made to solve such a problem, and an object of the present invention is to obtain an organic waste treatment method and apparatus capable of obtaining an efficient treatment effect with respect to input energy having a high cell membrane decomposition rate. Yes.

(1) The organic waste treatment method according to the present invention is characterized in that the impact water pressure treatment is performed to generate a shock water pressure on the organic waste before the dehydration step to destroy the cell membrane of the microorganism. .

(2) In addition, the organic waste treatment method according to the present invention is characterized in that impact water pressure treatment is performed to generate a shock water pressure on the organic waste before the methane fermentation step to destroy cell membranes of microorganisms. To do.

(3) Moreover, when performing a methane fermentation process in two steps of an acid fermentation process and a methane production | generation process among the things of said (2), an impact hydraulic pressure process is performed before and behind an acid fermentation process. is there.

(4) Further, the impact water pressure in the impact water pressure treatment in the above (1) to (3) is an impact water pressure induced by a gas convergent detonation wave.

(5) Moreover, the organic waste processing apparatus according to the present invention includes a processing chamber for storing organic waste, and an impact hydraulic pressure for generating impact hydraulic pressure on the organic waste in the processing chamber to perform impact hydraulic processing. A generator and a dehydrator for dehydrating the organic waste subjected to the impact water pressure treatment are provided.

(6) Further, a processing chamber for storing organic waste, an impact hydraulic pressure generating device for generating impact hydraulic pressure in the organic waste in the processing chamber to perform impact hydraulic pressure processing, and the organic material subjected to the impact hydraulic pressure processing And a methane fermentation apparatus that performs methane fermentation of waste.

(7) Also, a first treatment chamber for storing organic waste, a first impact hydraulic pressure generating device for generating impact hydraulic pressure on the organic waste in the first treatment chamber to perform impact hydraulic treatment, 1 Acid fermentation apparatus that performs acid fermentation of organic waste that has been subjected to impact hydraulic pressure treatment by an impact hydraulic pressure generation apparatus, a second treatment chamber that stores organic waste acid-fermented by the acid fermentation apparatus, and the second A second impact water pressure generating device for generating impact water pressure on organic waste in the processing chamber to perform impact water pressure processing, and methane for generating methane of the organic waste subjected to the impact water pressure treatment by the second impact water pressure generating device And a generating device.

(8) In addition, the impact water pressure generator in (5) to (7) described above converges detonation waves generated by the combustion of fuel to generate an ultrahigh-pressure convergent detonation wave, It is a gas converging detonator that generates impact water pressure on organic waste by propagating to the organic waste in the processing chamber.

In the present invention, since the cell membrane of the microorganism in the organic waste is destroyed by impact water pressure, since the components in the microorganism can be decomposed, the biodegradability in the methane fermentation process is high, and the amount of methane gas generated is reduced. The amount of dehydrated cake generated can be greatly reduced. Moreover, since the liquid component in the microorganism can be dehydrated, the dehydration efficiency can be increased, the water content of the dehydrated cake can be decreased, and the disposal efficiency can be improved.
In addition, underwater shock waves are generated by convergent detonation waves to destroy the cell membranes of microorganisms, and the shock water pressure is applied to the microorganisms by these underwater shock waves to destroy the cell membranes. The destruction performance is superior, and the treatment efficiency is higher than that of the conventional ultrasonic treatment.

[Embodiment 1]
FIG. 1 is an explanatory diagram of a processing flow of an organic waste processing method according to an embodiment of the present invention.
The organic waste treatment method according to the present embodiment is targeted for sludge generated in the process of sewage treatment as an example of organic waste, and generates impact water pressure in the sludge concentration step 1 and the concentrated sludge. Impact water pressure treatment step 3 for destroying the cell membrane of microorganisms in the sludge, methane fermentation step 5 for performing methane fermentation of the sludge subjected to microorganism cell membrane destruction, and dehydration step 7 for dewatering the sludge after methane fermentation, It has.
Hereinafter, it demonstrates with the apparatus used about each process.

(1) Sludge concentration step Sludge concentration step 1 is a step of concentrating the concentration of 0.5 to 1.0% sludge discharged in the process of sewage treatment to about 4.0% concentration. Examples of equipment used in the sludge concentration step include a gravity sludge concentration device and a centrifugal concentration device.

(2) Impact water pressure treatment process The impact water pressure treatment process 3 is a process of generating a shock water pressure on the sludge concentrated in the sludge concentration process 1 to destroy the cell membrane of microorganisms in the sludge. As a means for generating the impact water pressure, for example, a gas convergence detonator can be used. A gas convergent detonator is a device that converges detonation waves generated by the combustion of fuel to generate ultrahigh-pressure detonation waves, and propagates the detonated waves to sludge in a processing chamber. It generates shock water pressure.
FIG. 2 is a cross-sectional view of a main part of the gas convergence detonator 8. As shown in FIG. 2, the gas convergent detonator 8 includes an ignition chamber 9 that receives a fuel and an oxidant to generate detonation waves, a later-described dispersion unit 17 that communicates with the ignition chamber 9, and a convergence chamber. And a combustion chamber 10 composed of 23.

The ignition chamber 9 is formed in a cylindrical shape, and an ignition plug 9a as an ignition device for igniting fuel intermittently is provided at one end of the ignition chamber 9.
The ignition chamber 9 is provided with a shellkin spiral 9 b made of a spiral metal extending in the axial direction of the ignition chamber 9. The shellkin spiral 9b induces detonation by accelerating the flame generated by the ignition plug 9a igniting the fuel.
As shown in FIG. 2, the ignition chamber 9 is supplied with a fuel such as propane and an oxidizing agent (air) for combustion.

The main body 11 constituting the combustion chamber 10 is divided into an upper main body 11A and a lower main body 11B, which are sealed by a seal 11C and connected by bolts or the like (not shown).
The upper body 11 </ b> A is provided with a dispersing portion 17, and the above-described ignition chamber 9 communicates with the dispersing portion 17. The dispersion part 17 is formed by an upper member 19 and a lower member 21, and has a disk-like space 17 </ b> A that greatly expands in the radial direction from the ignition chamber 9 and a plurality of positions in the circumferential direction at the outer periphery of the disk-like space 17 </ b> A. The primary pores 17B are formed through, an annular space 17C that communicates with the plurality of primary pores 17B, and a plurality of secondary pores 17D that are formed through the annular space 17C. A mixture of fuel and oxidant is supplied to the ignition chamber 9, the dispersion portion 17, and the convergence chamber 23 described later. Thus, the detonation wave generated by the detonation induced by the air-fuel mixture in the ignition chamber 9 is propagated through the disk-shaped space 17A, the primary pore 17B, the annular space 17C, and the secondary pore 17D. And are introduced into the next convergence chamber 23.

The converging chamber 23 is formed between the curved rotating inner surface of the lower main body 11B and the outer peripheral surface of the lower protruding portion 21A of the lower member 21, and the space cross section gradually decreases toward the center and toward the central portion. It is formed to change direction.
A stepped piston 25 is housed in the inner space of the lower projection 21A of the lower member 21 so as to be movable up and down. Pipes 27A and 27B from the hydraulic control device 27 communicate with the upper and lower spaces of the large-diameter member 25A of the stepped piston 25, respectively.

  The lower end portion of the small diameter member of the stepped piston 25 forms a valve portion 25B having a tapered portion, and cooperates with a tubular valve seat body 29 attached to the central portion of the curved rotation surface of the lower main body 11B. The tubular valve seat body 29 has a large-diameter valve seat portion 29A formed at an upper portion and a tubular portion 29B extending downward therefrom. In the center of the upper surface of the valve seat portion 29A, a tapered valve seat that is locked by a valve portion 25B that is a tapered portion formed at the lower end portion of the stepped piston 25 is provided. A cylindrical injection hole 31 that extends and opens is connected to a treatment chamber 33 that stores sludge to be treated at its outlet opening end 31A.

The operation | movement at the time of impact water pressure processing by the gas convergence detonation generator 8 comprised as mentioned above is demonstrated.
First, in the state of FIG. 2, the mixture of fuel and oxidant is ignited in the ignition chamber 9, and the generated flame is accelerated by the shellkin spiral 9b to induce detonation. The generated detonation wave is dispersed through the dispersion chamber 17 and introduced into the convergence chamber 23. In this state, the stepped piston 25 receives the back pressure from the pipe 27A according to the hydraulic control device 27 as shown in FIG. 2, and the valve portion 25B of the stepped piston 25 closes the valve seat portion 29A. Yes.

A plurality of detonation waves introduced from the dispersion chamber 17 to the convergence chamber 23 travel downward in the convergence chamber 23. However, since the cross-sectional area of the convergence chamber 23 decreases downward, The detonation wave is converged into a super high pressure convergent detonation wave.
In synchronism with the generation of the convergent detonation wave, hydraulic pressure is instantaneously applied from the pipe 27B by the hydraulic control device 27, and the stepped piston 25 is raised by this instantaneous pressure, and the valve portion 25B, the valve seat portion 29A, A flow path is formed between the two. Therefore, the convergent detonation wave instantaneously travels downward through the injection hole 31 from this flow path and propagates from the outlet opening end 31A to the sludge 35 of the processing chamber 33.
This operation can be performed several times to several tens of times per second, and the number of times that the convergent detonation wave propagates to the sludge may be appropriately adjusted according to the amount of the processing target, the size of the microorganism, and the like. In order to prevent the combustion exhaust gas in the convergence chamber 23 from flowing into the processing chamber, the stepped piston 25 is lowered immediately after propagation of the convergent detonation wave to close the flow path, and the combustion exhaust gas is exhausted from an exhaust hole (not shown). To do.

The convergent detonation wave propagated to the sludge induces an underwater shock wave in the sludge, and this underwater shock wave propagates to minute animals and plants and microorganisms in the sludge as shown in FIG. 3, and is shocked to these animals and plants and microorganisms. Applying forces such as compression, expansion, and shearing, the membranes of these animals and plants and microorganisms are destroyed. In addition, in FIG. 3, the mechanism of the microbial cell membrane destruction accompanying the progress of the underwater shock wave is illustrated in (a) to (e) as time elapses.
As described above, in the present embodiment, an underwater shock wave is generated by a convergent detonation wave, and a shock water pressure is applied to a microorganism by this underwater shock wave so as to destroy the cell membrane. It is excellent in cell membrane destruction performance and has higher processing efficiency than conventional ultrasonic treatment.

(3) Methane fermentation process The methane fermentation process 5 is a process that decomposes the BOD / COD components in sludge in which the cell membrane of microorganisms has been destroyed by anaerobic microorganisms, mainly methane bacteria, into methane gas, carbon dioxide and water. is there.
In the present embodiment, since the cell membrane of the microorganism is destroyed in the impact water pressure treatment step 3 and biodegradability is increased, the amount of methane gas generated can be increased, compared with the case where such treatment is not performed. Therefore, an increase of about 1.5 times of methane gas is expected.

(4) Dehydration process The dehydration process is a process of dewatering sludge after methane fermentation. Examples of the apparatus include a belt press and a centrifugal dehydrator.
In the present embodiment, since the microbial cell membrane has been destroyed in the impact water pressure treatment step 3 and the contents of the microorganisms have leaked, the dehydration efficiency is high and the amount of dehydrated cake generated can be reduced by about 40%.
The dehydrated cake that has been dehydrated is either used for landfill or incinerated.

As described above, in the present embodiment, the impact water pressure treatment step is provided before the methane fermentation step, and the cell membrane of the microorganism is destroyed by the impact water pressure in the impact water pressure treatment step. Is highly biodegradable and can increase the amount of methane gas generated. Also, the dewatering efficiency is high and the amount of dehydrated cake generated can be greatly reduced.
In addition, underwater shock waves are generated by convergent detonation waves to destroy the cell membranes of microorganisms, and the shock water pressure is applied to the microorganisms by these underwater shock waves to destroy the cell membranes. The destruction performance is excellent, and the processing efficiency is higher than that of the conventional ultrasonic treatment.
In addition, since the impact water pressure generator in the present embodiment is a gas convergent detonator, by adjusting the gas mixture filling pressure, the intensity of the underwater shock wave can be easily adjusted according to the properties of the organic waste. (Processing effect) can be significantly changed, and an optimum response can be made according to the properties of the processing object.
In addition, since no poisonous substances or harmful substances are used, there is a feature that there is no concern about secondary pollution during the treatment work and the disposal work of the treated organic substances.

  In the above example, it is assumed that there is a methane fermentation process, but even if there is no methane fermentation process, as shown by the broken line in FIG. It goes without saying that performing step 3 can increase the dewatering efficiency and reduce the amount of dehydrated cake generated.

[Embodiment 2]
FIG. 4 is a flowchart for explaining the flow of the second embodiment of the present invention, and the same reference numerals are assigned to the same processes as those in FIG. In this Embodiment, when performing the methane fermentation process in Embodiment 1 in two steps, the acid fermentation process 9 and the methane production | generation process 13, before and after the acid fermentation process 9, an impact hydraulic pressure process (1st impact hydraulic pressure process). Step 3 and the second impact water pressure treatment step 11) are performed.
By performing the impact water pressure treatment (first impact water pressure treatment step 3) before the acid fermentation step 9, the efficiency of acid fermentation is increased and the dehydrated cake is reduced due to the cell membrane destruction of the microorganism described in the first embodiment. it can.
In addition, by performing impact hydraulic pressure treatment (second impact hydraulic pressure treatment step 11) after the acid fermentation step 9, the acid-fermenting bacteria grown in the acid fermentation step 9 can be killed. Bacteria can be mainly used, and the efficiency of the methane production treatment can be further increased.

In the first and second embodiments, the dehydration process is performed after the methane fermentation without performing the impact hydraulic process. However, the impact hydraulic process may be performed after the methane fermentation process. By performing the impact water pressure treatment after methane fermentation, microorganisms grown in methane fermentation can be killed and their cell membranes can be destroyed, dehydration efficiency can be increased, and the amount of dehydrated cake generated can be reduced.
In the first and second embodiments, the sludge generated in the sewage treatment is shown as an example of treatment. However, the organic waste targeted by the present invention is not limited to this, and other Examples of such items include feces, raw urine, sewage sludge, septic tank sludge, combined septic tank sludge, agricultural sludge, and sludge.

It is explanatory drawing explaining the flow of a process of the organic waste processing method which concerns on one embodiment of this invention. It is explanatory drawing explaining a part of gas convergence detonation generator used for one embodiment of this invention in detail. It is explanatory drawing explaining the effect | action of the underwater shock wave with respect to microorganisms. It is explanatory drawing explaining the flow of a process of the organic waste processing method which concerns on other embodiment of this invention.

Explanation of symbols

8 Gas convergence detonator 9 Ignition chamber 10 Combustion chamber 33 Processing chamber

Claims (8)

In the organic waste processing method, the organic waste processing method is characterized in that, before the dehydration step, impact hydraulic pressure treatment is performed to generate a shock hydraulic pressure on the organic waste to destroy cell membranes of microorganisms. In the organic waste processing method, the organic waste processing method is characterized in that before the methane fermentation step, impact hydraulic pressure treatment is performed to generate a shock hydraulic pressure on the organic waste to destroy cell membranes of microorganisms. The organic waste treatment method according to claim 2, wherein impact water pressure treatment is performed before and after the acid fermentation step when the methane fermentation step is performed in two stages of an acid fermentation step and a methane production step. The organic waste treatment method according to any one of claims 1 to 3, wherein the impact water pressure in the impact water pressure treatment is a shock water pressure induced by a gas convergent detonation wave. A treatment chamber for storing organic waste, an impact water pressure generating device for generating impact water pressure on the organic waste in the treatment chamber and performing impact water pressure treatment, and dewatering of the organic waste subjected to the impact water pressure treatment An organic waste treatment apparatus comprising: a dehydrating apparatus for performing the dehydration apparatus. A processing chamber for storing organic waste, an impact hydraulic pressure generating device for generating impact hydraulic pressure on the organic waste in the processing chamber and performing impact hydraulic processing, and methane fermentation of the organic waste subjected to the impact hydraulic processing An organic waste treatment apparatus comprising: a methane fermentation apparatus that performs A first treatment chamber for storing organic waste, a first impact hydraulic pressure generating device for generating impact hydraulic pressure on the organic waste in the first treatment chamber to perform impact hydraulic pressure processing, and the first impact hydraulic pressure generating device Acid fermentation apparatus that performs acid fermentation of organic waste that has been subjected to impact hydraulic pressure treatment, a second treatment chamber that stores the organic waste that has been acid-fermented by the acid fermentation apparatus, and organicity in the second treatment chamber A second impact water pressure generating device for generating an impact water pressure by generating an impact water pressure on the waste, and a methane generating device for generating methane of the organic waste subjected to the impact water pressure treatment by the second impact water pressure generating device. An organic waste disposal apparatus characterized by comprising. The impact water pressure generator generates an ultra high pressure convergent detonation wave by converging detonation waves generated by fuel combustion, and propagates the convergent detonation waves to organic waste in the processing chamber. The organic waste disposal apparatus according to any one of claims 5 to 7, wherein the apparatus is a gas convergent detonator that generates impact water pressure on the waste.

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