JPS5840196A - Preparation of methane-fermenting sludge - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a highly concentrated sludge for methane fermentation.

Methane fermentation has attracted attention as a means of producing energy using microorganisms since the first oil crisis, and has been carried out using agricultural, forestry, fisheries, livestock waste, urban waste, industrial wastewater, etc. as raw materials. Generally, the methane-fermenting bacteria used are collected from nature and used after being acclimatized according to the raw material. The methane fermentation capacity of acclimatized sludge varies and is easily changed depending on various conditions. For this reason, the product that is sedimented and concentrated in the device is usually transported to a fermentation tank using a pump or the like.

Methane fermentation is preceded by microorganisms converting high-molecular organic compounds into low-molecular molecules, producing and accumulating volatile organic acids,
Dehydrogenation from the organic acids generated there.

The process follows the synthesis of methane from hydrogen and carbon dioxide after decarboxylation. In order to perform methane fermentation with high efficiency, it is necessary to carefully select a group of microorganisms that are useful for the acid production process in the first stage, and a group of methane bacteria that perform methane production in the second stage, and to maintain an appropriate number of bacteria.

The conventionally used concentrated sludge contains C/C, which is a culture raw material.
Due to an inappropriate N ratio, a large amount of organic acids that methane bacteria do not like are produced, the methane production ability is low, and the concentrated sludge is so viscous that it is difficult to obtain it.

As a result of research focusing on these points, the present inventors have arrived at the present invention, and have recognized that it is necessary to grow methane bacteria in a short period of time and to adjust the growth balance between acid-producing bacteria and methane bacteria. As a result of repeated efforts regarding this adjustment method, we have found that the above-mentioned bacterial group can be adjusted by adding a mixture of bentonite and polishing sand in a certain ratio or river bottom silt, which is a homogeneous inorganic substance, and performing anaerobic culture to grow the bacteria. It was confirmed that this can be achieved extremely effectively. The culture solution contains cellulose and hemicellulose as the main carbon source, and polypeptone and hemicellulose as the main nitrogen source.
Use yeast eski etc. More preferably, it enhances the growth of bacteria)
By adding a small amount of a substance that promotes bacterial growth, the growth of bacteria was greatly promoted, leading to the completion of the present invention. As the hemicellulose material, soybean seed coat (agricultural waste produced during the soybean oil manufacturing process) is used, which is slightly decomposed and solubilized with enzymes, and then cellulose and a small amount of glucose are mixed with it.

A medium is prepared by adding polypeptone, yeast extract, tributicase, etc. as a nitrogen source, and trace amounts of glutamine, asparagine, and inositol as growth promoting substances.

Add to this the above, bentonite and polishing sand (mixing ratio of 1:9)
Add 600y of mixture, river bottom silt, etc. to 1ρ of culture solution,
Methane-fermenting bacteria are grown rapidly under anaerobic conditions while keeping the temperature and pH at optimal conditions to prepare a sludge with a large number of methane bacteria, which is then provided as methane sludge.

The method for culturing methane-fermenting bacteria in the present invention will be described in detail. The hemicellulose material to be added to the culture solution is made by suspending soybean seed coat (agricultural waste produced in the soybean oil manufacturing process) 752 in tap water, sterilizing it under high pressure at 126°C for 216 minutes, allowing it to cool, and adding the enzyme cellulase (cellulase).・Added 0.1 to 1% (weight ratio) of Lurosin AC (produced by Ueda Chemical Co., Ltd., matured black mold), pH around 3.5 to 4.0, temperature 26 to 5.
Enzyme is allowed to act at 0°C to obtain a solution containing low molecular weight hemicellulose. Cellulose powder (P paper powder, Toyo Kagaku Sangyo product, 1% by weight) and glucose (0.3% by weight) were added to this solution, and polypeptone (manufactured by Daigo Nutrition Co., Ltd., 0.06% by weight) was added as a nitrogen source. weight), yeast extract (DIFC
0.06% by weight (manufactured by Wako Pure Chemical Industries, Ltd.) and tributicase (manufactured by BBL, 0.06% by weight) and tributicase (manufactured by BBL, 0.06% by weight) and L-glutamine (manufactured by Wako Pure Chemical Industries, Ltd., 0.005% by weight) as a growth promoting substance. Anti-jukui λL-asparagine (manufactured by Wako Pure Chemical Industries, Ltd.).

0.005% by weight), inositol (manufactured by King Chemical Co., Ltd., 0.005% by weight) and L-cystine hydrochloride (manufactured by Hikari Pure Chemical Industries, Ltd., 0.005% by weight). In addition, 0.0005% each of vitamins B1 and B2, 0.001% of vitamin B6, and 0.004% of vitamins (all vitamins, manufactured by Wako Pure Chemical Industries, Ltd.) are added (vitamin B1 and B2, which are essential for growth). = Thiamine hydrochloride,
Vitamin B2 = riboflavin, vitamin B6 = pyridoxine hydrochloride, vitamin = vitamin 1).

In the present invention, various organic compounds added to the culture solution are summarized as 1 to 4 below.

1 Hemicellulose solubilized liquid (obtained from soybean seed coat).

Cellulose powder, glucose 2, yeast extract, tributicase, polypeptide 7'/3
L-glutamine, L-asparagine, inositol, L
-Cystine hydrochloride 4 Vitamin B1. B2. B6. Concerning the concentration of the main carbon source supplied in the culture medium in step 1, the hemicellulose solubilized solution is prepared after enzymatic reaction at the concentration described above, and is diluted to 7 to 10 parts before use. The total sugar content in the culture solution derived from the hemicellulose solubilized solution may be 0.02 h (relative to weight).

2.3.4 each shows the effect of strengthening the growth of acid-producing bacteria and methane bacteria, and if added to the total, the growth of acid-producing bacteria will be abnormally increased, so ultimately the inclusion of methane bacteria will increase the growth of acid-producing bacteria. This has the effect of lowering the ratio. The upper limit of addition is O, OS or about 0.3%.

The mixing ratio of bentonite, which is an inorganic substance containing acid-producing bacteria and methane bacteria, and polishing sand is 1:9 and 2:8, and the addition ratio to the culture solution is preferably 20 to 60% (by volume). The inorganic material may be silt θ11 bottom blue clay) or sometimes tuffaceous sand (derived from volcanic ash). However, the pf (pf) when mixed into the culture solution must be maintained at 6.0 to 7.Oi/i.

The culture solution containing the clay or silicic acid-based fine powder such as neutralized bentonite described in detail above is brought to an anaerobic state, and in this case, it can be kept in a large syringe, or more conveniently, it can be placed in a large container and allowed to stand still. It is done. Inoculate the inoculum into a container kept at 37℃ and let it grow for 3 to 4 days, then collect and analyze the castle gas to confirm methane production, and at the same time measure the number of methane bacteria in the sediment by diluting it on a plate. Growth was confirmed by the anaerobic culture method (anaerobic gas pack was used, replacement gas included s o % N2°, 10% H2, 10% CO2 (relative to volume)), and Kyokou (derived from 7 lapin F42°, which is unique to methane bacteria). Through detection, the number of bacteria can be measured.

A mixture of bentonite and polishing sand (1:9 mixture), silt sludge or tuffaceous sand 102, 10 me of culture solution, and 10 me of sterilized water are added to grow methane-fermenting bacteria anaerobically. The number of inoculated methane fermenting bacteria (acid producing bacteria and methane bacteria) is 5 x 106/1m
As e, the number of reeds when cultured at 37℃ for 4 days is
Shown in the table.

Table 1 *(Acid-producing bacteria) + (Methane bacteria) After the methane fermentation bacteria have grown, the sludge is left to stand naturally and the sludge is examined for the presence of methane fermentation bacteria in the slag. Table 2 shows the results of examining the distribution of methane fermentation bacteria. Some of the methane-fermenting bacteria are contained in the sediment.

Table 2 As described above, according to the present invention, a highly concentrated sludge for methane fermentation can be obtained by enclosing methane-fermenting bacteria with clay or silicic acid-based fine powder such as neutralized bentonite to form a sludge. did it.

Name of agent: Patent attorney Toshio Nakao and 1 other person = 5

Claims (1)

[Claims] A method for producing a sludge for methane fermentation in which methane-fermenting bacteria are encapsulated in clay or silicic acid-based fine powder such as neutralized bentonite.