JPS58128198A - Method and device for methane fermentation - Google Patents

Abstract

PURPOSE:To ferment methane effectively even from base material such as animal org. waste by supplying the liquid base material obtained by making org. waste soluble into a methane fermenting tank in a way as to contact successively with the bacteria held in said tank. CONSTITUTION:First, a 3-way valve 7 is operated to communicate a suction pipe 9 with a circulating pipe 2, and the liquid base material 4 which is beforehand made soluble in a tank 8 is sucked up with a pump 3 into a methane fermenting tank 1. Then, the valve 7 is operated to disconnect the pipe 7 and to open the pipe 2. Thereafter, the material 4 in the tank 1 is circulated with the pump 3 and the solubilized liquid base material 4 is subjected to required methane fermentation by the facultative anaerobic bacteria and methane bacteria held in bacterium holding members 5, whereby methane is formed. The formed methane is removed with a removing pipe 11, and the overflow liquid is discharged into a settling tank 13. The sludge accumulated in the inside bottom is discharged with a drain part 10.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a methane fermentation method and apparatus for producing methane using waste products such as agricultural waste, fishery waste, and other agricultural waste.

In general, incineration is often used to dispose of waste such as livestock products, marine products, agricultural products, etc., but in recent years, the use of this waste as an energy resource has been developed.

That is, methane is obtained by subjecting the waste to methane fermentation. The present inventors conducted various studies on the methane fermentation and found that there were various problems.

As is well known, methane is produced by carbohydrates and fats.

Organic base materials such as proteins are decomposed and solubilized by aerobic bacteria in advance, and then facultative anaerobic bacteria are applied to produce higher fatty acids, amino acids, sugars, and lower fatty acids, which are then converted into hydrogen and carbon dioxide. , acetic acid, propionic acid, lower fatty acids, are alcoholized, and methane bacteria are applied to these to obtain methane. Since methane bacteria are anaerobic bacteria, methane fermentation is generally carried out in a sealed tank.

By the way, among the base materials, especially animal organic wastes such as electricity storage processing wastes and fishery wastes have a high fat content, and this can be used as it is to efficiently or continuously carry out the general methane fermentation mentioned above. That is almost impossible.

This means that animal organic waste generally contains 10-26% fat;
These fats are decomposed into glycerin and higher fatty acids, but the higher fatty acids such as palmitic acid, stearic acid, and oleic acid are chemically and biochemically stable, and their low Molecularization is delayed.

As new substrates are added through the daily treatment of waste, higher fatty acids precipitate and accumulate in the tank, and are adsorbed onto the bacterial surface, inhibiting methane fermentation.

In order to effectively methane ferment all of these animal organic wastes, it is necessary to reduce the fat concentration in the tank to a low fat concentration of 500 PPM or less, which requires diluting the fermentation stock solution by at least 200 times. In processing several tons of waste every day, the equipment would be extremely large, making it practically unfeasible.

The present invention takes these problems into consideration and aims to effectively carry out methane fermentation even when the base material is animal organic waste.

In order to achieve this object, the present invention holds bacteria in a methane fermentation tank with a holding member, and sequentially supplies liquid raw materials made by solubilizing organic waste to the bacteria so that they come into contact with the bacteria. This is the basic method.

Further, in order to achieve the above object, the present invention includes a seedling holding member that holds bacteria in a methane fermentation tank, a circulation pipe that circulates the base material in the methane fermentation tank, The basic configuration is that a pump is provided in the circulation pipe.

With the above method and configuration, the bacteria in the methane fermentation tank will not flow out or settle, and will not only multiply on the seedling holding member, but the substrate will come into contact with the bacteria one after another and methane fermentation will be carried out well. effective.

An embodiment of the present invention will be described below with reference to the drawings. In FIG. is provided so that the solubilized liquid base material 4 in the methane fermentation tank 1 is circulated. 1IfI A plurality of seedling holding members 6 are arranged in the methane fermentation tank 1. The seedling holding member 5 has a shape that allows methane bacteria and other facultative anaerobic bacteria to easily adhere thereto. For example, as shown in Figure 4a, a combination of several to several dozen Saran fibers or plastic fibers of 10 to 400 deniers, a branch-like structure as shown in Figure 4, and a fiber separator as shown in Figure C. - It can be made into a zigzag shape as shown in the figure d, or a perforated sheet shape as shown in the figure e.

The seedling holding members 6 may be arranged in parallel to the flow of the base material 4 as shown in FIG. 2, or may be arranged horizontally as shown in FIG. 3.

Equalizing plates 6 are provided in the methane fermentation tank 1 at positions corresponding to the upper and lower portions of the seedling holding member 5. Therefore, the liquid base material 4 flows while contacting each seedling holding member 6 at a constant flow rate. A three-way valve 7 is provided in a part of the circulation pipe 2, and the liquid base material 4 can be freely sucked up from the base material tank 8 using a suction pipe 9.
A drain/section 1o is provided at the bottom of the methane fermentation tank 1. A methane extraction pipe 11 and an overflow pipe 12 are connected to the upper part of the methane fermentation tank 1.
is connected to the settling tank 13.

In the above configuration, first, the three-way valve 7 is operated to connect the suction pipe 9 to the circulation pipe 2. By operating the pump 3 in this state, the pre-solubilized liquid base material 4 in the base material tank 8 is sucked into the methane fermentation tank 1. When the required amount of base material 4 flows into the methane fermentation tank 1, the three-way valve 7 is operated to shut off the suction pipe 9.
Open the circulation vibrator 2.

Next, the base material 4 in the methane fermentation tank 1 is circulated by the operation of the pump 3. This circulation can be carried out either slowly (4 rotations per day) or rapidly (1) intermittently for 10 minutes every 2 hours.
The number of cycles per minute is preferably increased if the base material 4 has a large amount of fat.

The solubilized and liquid base material 4 undergoes the required methane fermentation by the facultative anaerobic adult seedlings held by the seedling holding member 6 and methane bacteria to produce methane. This generated methane is taken out by a methane take-out pipe 11. In addition, the overflow liquid is appropriately discharged to the settling tank 13 through the overflow pipe 12,
The sludge that accumulates on the inner bottom of the methane fermentation tank 1 is removed from the drain section 1.
It is discharged from o.

The results of fermentation using the above device are as shown in Figure 6.

Base material 4 is ham/sausage 60. Piece of meat 40. Material with fat content of 13% at organic loading of 2.5%, /p, D
Ferment it with The solid line in the graph shows the methane generation situation when fermentation was carried out using a device that does not have bacterial cell retention in a general tank. Fermentation inhibition occurs after about 4 weeks, and it has almost stopped by the 6th week. Become. The broken line in graph B indicates fermentation using the apparatus of the present invention.

This result is because the bacteria are stably held in the seedling holding member 6 and are multiplied, while the base material 4 circulates and comes into contact with the bacteria, so the bacteria settles downward or fat content is absorbed by the bacteria. This is thought to be due to the fact that it does not adsorb and inhibit bacterial activity.

Moreover, the fact that it temporarily decreased in the 6th week and stabilized in the 8th to 9th week is probably due to the fact that the circulation direction of the base material 4 was reversed. That is, the circulation direction is basically from the bottom to the top of the methane fermentation tank 1, but in this case, many soap-like bubbles are generated on the liquid surface of the base material 4, and some bubbles come out to the methane extraction vibrator 11. Therefore, in order to eliminate the air bubbles, the circulation was reversed after 7 weeks, which probably caused a change in the state of bacterial cell retention and resulted in a decrease in bacterial cell retention.

As explained above, according to the present invention, the bacteria in the methane fermentation tank are stabilized, and the circulating substrate sequentially comes into contact with the bacteria, that is, the substrate is in an agitated state, and the bacteria are It is a device that effectively performs methane fermentation under the action of methane, and is particularly effective in methane fermentation even in animal organic waste with a high content of fat, and is useful for industrial waste treatment.
It is effective for energy production and has great industrial effects.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a methane fermentation device according to an embodiment of the present invention;
2 and 3 are explanatory diagrams of the arrangement of the seedling holding member in the same device, FIGS. 4 a to 4 e are configuration diagrams of the seedling holding member, and FIG.
The figure is a gas conversion rate characteristic diagram. 1...Methane fermentation tank, 2...Circulation pipe, 3...Pump, 4...Base material, 5.
... Seedling holding member, 7... Three-way valve, 8...
... Base material tank, 9 ... Suction pipe, 1
1...Methane extraction pipe. Name of agent: Patent attorney Toshio Nakao and 1 other person 2nd
Figure 3 Figure 4 (tsu,) tb+ ccn (d)
(ε) Figure 5 - 10 shells 1 ■ Yield

Claims (1)

[Claims] (1) Bacteria are held in a methane fermentation tank by a holding member, and a liquid base material made of soluble organic waste (F) is sequentially supplied to the bacteria so as to be in contact with the bacteria. ('4) The methane fermentation method according to claim 1, characterized in that the substrate is supplied to the bacteria held by a circulation means. (3) Substrate The method for methane fermentation according to claim 2, characterized in that the circulation direction of the methane fermentation tank can be switched. A methane fermentation device comprising: a circulation pipe for circulating the base material in the methane fermentation tank; and a pump provided on the circulation pipe. (6) The methane fermentation device according to claim 4, wherein the pump is provided so as to be rotatable in forward and reverse directions.