JPS60244283A - Preparation of methane-fermentation microorganism - Google Patents

Abstract

PURPOSE:To facilitate the handling of microorganism in the methane fermentation process using microorganisms separated in a nearly pure state, by carrying out the collection of cultured microorganisms in the presence of a clay mineral capable of promoting the agglutination of the microorganism and protecting the microorganism. CONSTITUTION:Microorganisms are separated in pure or nearly pure state from the methane fermentation microorganisms by the conventional technique for the separation of microorganisms. The separated microorganisms are cultured by conventional technique, and the cultured microorganisms are collected. The collection of the microorganisms is carried out in the passage of a clay mineral capable of promoting the agglutination of the microorganisms, protecting the microorganisms, and accelerating the fermentation. The clay mineral is montmorillonite, kaolinite, halloysite, etc. or their mixture. The microorganisms are agglutinated around the particles of the clay mineral, and can be precipitated and separated by small centrifugal force. The collected microorganisms are mixed, and reconstituted as the methane-fermentation microorganism.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a methane fermentation process. More specifically, it relates to the production of methane-fermenting microorganisms.

Structure of conventional examples and their problems Methane fermentation is a reaction in which methane is produced from organic matter through a biochemical reaction carried out by multiple types of microorganisms under anaerobic conditions. The multiple types of microorganisms that carry out this reaction are collectively called methane-fermenting microorganisms.

In nature, methane fermentation is observed in sludge at the bottom of rivers, ponds, and the sea. In current methane fermentation, these microorganisms in the sludge are transferred together with the sludge into a fermenter, and used after being adapted to various fermentation raw materials. Additionally, when constructing a new fermenter or repairing a fermenter, it is necessary to transport and handle the sludge extracted from the fermenter, but this requires handling of sludge that is large in volume. There are many problems such as handling and uncleanliness.

In response, attempts have been made to separate the methane-fermenting microorganisms in sludge into pure or near-pure forms, industrially culture them, collect them, and mix them to reconstitute the methane-fermenting microorganisms for use. be. This has many advantages, such as being advantageous in terms of volume, being less likely to become unclean, and being able to replace the microbial content with something that has a faster biochemical reaction rate. However, since methane-fermenting microorganisms are anaerobic bacteria, they are susceptible to contact with oxygen (air), and because they have lived in stable environments, they are vulnerable to drastic changes in the environment. Therefore, handling such as bacterial collection, storage, and transportation is fraught with difficulties.

Purpose of the Invention The present invention provides a method for culturing the aforementioned pure or nearly pure microorganisms, collecting and mixing them, and facilitating handling of the microorganisms and increasing their stability when used as methane-fermenting microorganisms. It is something to do.

Structure of the Invention In the present invention, a microorganism isolated in a pure or nearly pure form from among methane-fermenting microorganisms is used. This is done using known microbial isolation techniques. The culture method is also an application of known technology.

Now, in the present invention, when collecting the cultured microorganisms, clay minerals are added which help the flocculation of the microorganisms, have the effect of protecting the microorganisms, and have the effect of promoting fermentation.

Furthermore, the collected microorganisms are mixed to reconstitute the methane-fermenting microorganisms.

The methane-fermenting microorganism thus obtained is used in a fermenter to perform fermentation.

Description of Examples The methane-fermenting microorganisms used in the present invention are further subdivided into:
There are three groups of microorganisms. The first type of microorganisms are those that decompose organic matter and produce low-molecular decomposition products, mainly acetic acid (decomposers). can be done. Therefore, as this microorganism, preserved strains of bacterial strain preservation institutions can be used, and pure isolation can be easily carried out using the plate culture method. In addition, a nearly pure mixed microorganism can be easily obtained using the enrichment culture method. Any microorganism may be used.

The second microorganism is a methane-producing microorganism, and is a microorganism that performs a methane production reaction, which is the final stage of methane fermentation. Although it is not easy to isolate pure microorganisms, the technology for pure isolation is already known, and as with degrading bacteria, strains from preservation institutions or strains isolated by oneself can be used.

The third microorganism is involved in the reaction of producing methane from acetic acid in cooperation with methane-producing bacteria, and its taxonomic position and mycological properties are unknown.

This microorganism can be concentrated to a near-pure form by performing enrichment culture using a medium containing acetic acid as a carbon source. Furthermore, culture can be promoted by allowing methane-producing bacteria to coexist during enrichment culture. - This enrichment culture is also reproducible and the enrichment culture is generally available.

Cultivation methods for decomposing bacteria and methane-producing bacteria are known, and cultivation is performed according to known culture methods.For microorganisms involved in the reaction of producing methane from acetic acid, first culture the methane-producing bacteria. An enriched culture of microorganisms involved in the reaction of producing methane from acetate and acetic acid is added to this and further cultivation is continued.

Now, when collecting microbial cells from the culture (collecting bacteria), clay is added to the culture. This is montmorillonite
Even clay minerals such as kaolinite and halloysite,
It may be a mixture thereof, or it may be clay mined from a geological layer mainly composed of clay minerals.

Microorganisms aggregate using clay mineral particles as cores, and as the particle size increases, the sedimentation rate increases. Next, microorganisms are collected by centrifugation, and microorganisms that aggregate and have an increased sedimentation rate are sedimented and separated by a small centrifugal force. That is, since bacteria can be collected under mild conditions, damage to microorganisms can be kept to a minimum.

The amount of clay mineral required at this time is equal to or greater than the dry weight of the microbial cells. Also, the centrifugal force required for centrifugation is 20
It is about 00G.

Furthermore, due to aggregation, microorganisms with a reduced surface area become less susceptible to the influence of air.

Next, the microorganisms collected in this way are mixed, stored, transported, and then transferred to a fermentation tank for use, during which time the clay minerals act as a protective agent. That is, although the killing rate of microorganisms has a negative correlation with the concentration of microorganisms (a well-known general rule), the protective effect is great because the microorganisms are densely packed due to aggregation. In addition, because the surface area is reduced, it is less susceptible to the effects of the outside world, so a protective effect is exerted.

Finally, it is transferred to a fermentation tank and used, and the accelerating effect is observed. Salts or hydroxides of iron and calcium also have the effect of promoting fermentation, and many clay minerals contain these.

Furthermore, small amounts of metal elements with multiple valences have the effect of promoting fermentation, and clay minerals usually contain these elements.

As described above, the effects of the present invention are that it facilitates bacterial collection, stabilizes handling, and promotes fermentation.

Claims (1)

[Claims] Methane-fermenting microorganisms are isolated in a pure or near-pure state using an enrichment culture method, cultured, and then clay minerals are added to collect the bacteria and mixed to reconstitute the methane-fermenting microorganisms. Production method of fermentation microorganisms.