JPH0611438B2 - Biological reaction method - Google Patents

Description

Description: TECHNICAL FIELD OF THE INVENTION The present invention relates to a biological reaction method for degrading a substrate by catabolic metabolism of a microorganism in the field of utilizing a microorganism such as water treatment and fermentation.

[Prior art]

BACKGROUND ART In wastewater and waste treatment and fermentation production using microorganisms, a bioreaction that decomposes a substrate by catabolism of microorganisms is performed. Such biological reaction is carried out by aerobic or anaerobic microorganisms under aerobic or anaerobic conditions. As a conventional biological reaction method, a method of allowing the reaction to proceed without controlling the temperature of the reaction system, and a method of controlling the temperature suitable for the growth of microorganisms, that is, a temperature near the maximum growth rate, are carried out. Although there are methods, in any case, there is a problem that the rate of substrate decomposition is low and the conversion rate of the substrate into microbial cells becomes high. The higher conversion rate to microbial cells means that the amount of microbial cells in the reaction system increases, and in the field of wastewater and waste treatment,
The increased amount of microbial mass is discharged as excess sludge, which causes a problem of secondary pollution in its treatment and disposal. In addition, in the fermentation field, the process of separating the final product from the microbial cells becomes complicated, and the surplus microbial cells are produced as a waste, which causes a problem in the treatment.

On the other hand, it is known that there are temperature conditions that show the maximum substrate decomposition rate in a temperature region different from the temperature region of the maximum growth rate, and attempts have been made to carry out biological reactions in such a temperature region (critical point). (Bact
eriological Review, Vol 26, P95-107). However, the maximum substrate decomposition rate in such a biological reaction method was obtained for dormant microorganisms, and if the biological reaction is continued in the above temperature range, the catabolic activity of the microorganisms will decrease and the substrate decomposition ability will decrease. As it drops
In some cases, since the amount of microorganisms decreases and the efficiency decreases, it is practically difficult to continue the biological reaction under the temperature condition of the maximum substrate decomposition rate to decompose the substrate.

[Object of the Invention]

The present invention is to solve the above problems, and the substrate decomposition efficiency can be improved by repeating the reaction in an environment in which the temperature conditions near the maximum substrate decomposition rate and the temperature conditions near the maximum growth rate of the microorganism are repeated. It is an object of the present invention to provide a biological reaction method which has a high biodegradation and a small increase in the amount of microorganisms.

[Structure of Invention]

The present invention is a biological reaction method for degrading a substrate by catabolic metabolism of a microorganism, characterized in that the microorganism is reacted in an environment in which temperature conditions near the maximum substrate decomposition rate and temperature conditions near the maximum growth rate are repeated. It is a biological reaction method.

In the present invention, biological reaction means water treatment, waste treatment,
This is a biological reaction that decomposes the substrates in the wastewater, raw materials, and other substances to be treated by the catabolic metabolism of microorganisms such as fermentation to produce treated products such as treated water and products.Aerobic and anaerobic biological reactions Including both. Examples of microorganisms used for such biological reactions include bacteria, filamentous fungi, yeasts, other microorganisms conventionally used for biological reactions, biomass composed of these organisms, activated sludge and the like.

When these microorganisms are allowed to carry out biological reactions under their own unique biological reaction conditions, for example, aerobic or anaerobic conditions, by changing the temperature of the reaction system, the maximum substrate decomposition rate at which the catabolic activity of the microorganism is maximized is obtained. The temperature condition shown and the temperature condition showing the maximum growth rate at which the increase of the microorganisms is maximum appear in different temperature regions. Since the substrate decomposition rate changes while continuing the biological reaction under the same temperature condition, the biological reaction is performed using dormant microorganisms, and the temperature at which the substrate decomposition rate becomes maximum is the temperature condition that shows the maximum substrate decomposition rate. To do.

The temperature conditions showing the maximum substrate decomposition rate and the maximum growth rate differ depending on each microorganism. For example, a mesophilic methanogen that is an absolutely anaerobic bacterium has a maximum substrate decomposition rate of 4
Klebsiella neumonie, which is a facultative anaerobic bacterium, has a maximum substrate decomposition rate of 41.
Aerobic aerobic bacteria Aerobic aerogenes has a maximum substrate decomposition rate of 41.8 at 8 ° C and a maximum growth rate of 27 ° C.
C., the maximum growth rate is 37.degree.

The substrate decomposition rate and the growth rate are substantially large in the temperature conditions of the maximum substrate decomposition rate and the maximum growth rate, and the temperature conditions in the vicinity thereof, usually within a range of ± 2 to 3 ° C. The temperature conditions near the substrate decomposition rate and the temperature conditions near the maximum growth rate are adopted.

Maximum substrate degradation rate, measured using dormant microorganisms, is the maximum intrinsic catabolic activity of the microorganism. However, this maximum substrate decomposition rate, which is specific to the microorganism, appears only when the maximum conditions are set, and therefore the activity gradually decreases when a biological reaction is carried out under a temperature condition near the maximum substrate decomposition rate. Further, under this temperature condition, the growth rate of the microorganisms shows a negative value, and the microorganisms tend to decrease.

On the other hand, when the biological reaction is carried out under the temperature condition near the maximum growth rate, the substrate decomposition rate is smaller than that under the temperature condition near the maximum substrate decomposition rate, the conversion rate to the microbial cells is high, and the amount of the microbial cells increases remarkably.

Therefore, when a microorganism is placed in an environment in which these two different temperature conditions are repeated, a catabolic activity in a biological reaction is high under a temperature condition near the maximum substrate decomposition rate, and a biological reaction with a large substrate decomposition rate is performed. When a similar biological reaction is performed on a microorganism whose activity has decreased due to temperature conditions near the maximum growth rate, the decreased activity of the microorganism increases due to growth, the decreased activity is activated, and maximum substrate decomposition occurs again. It was discovered that biological reactions could be performed at a speed. This tendency is due to the difference between aerobic and anaerobic microorganisms and
It is widely accepted regardless of differences in bacteria, filamentous fungi, yeasts, other microorganisms and their aggregates.

The time for performing a biological reaction in a temperature condition near the maximum substrate decomposition rate of a microorganism is the time before the catabolic activity decreases, and it varies depending on the microorganism that performs the biological reaction, but it is generally several hours to several days. For example, it is about 5 hours to 5 days. In addition, the time for carrying out the biological reaction under the temperature condition near the maximum growth rate is based on the time when the reduced activity is activated and the time when the decreased microbial body becomes constant, and it is desirable that both are the same, but in general, Is based on the time when the activity is activated, and at this time, the number of microbial cells tends to increase somewhat.
This time also varies depending on the microorganism, but it is generally about 10 hours to 5 days.

As a method of placing microorganisms in an environment in which these two temperature conditions are repeated, a biological reaction is performed under the temperature conditions near the maximum substrate decomposition rate and a main reaction part where the biological reaction is performed under the temperature conditions near the maximum substrate decomposition rate. A method of circulating a microorganism between two reaction parts of a growth activation part, and a method of alternately switching the two reaction parts between a biological reaction under a temperature condition near the maximum substrate decomposition rate and a biological reaction under a temperature condition near the maximum growth rate, etc. There is. By placing these two temperature conditions in a repetitive environment by these methods, high-rate substrate decomposition at temperature conditions near the maximum substrate decomposition rate and activated growth at the maximum growth rate are repeated, and the substrate as a whole It is possible to carry out a biological reaction with a high decomposition efficiency and a small amount of microorganisms.

The load given to these two reaction parts gives most of the load to the reaction part near the maximum substrate decomposition rate, increases the efficiency of biological reaction as the main reaction, and activates the activity in the reaction part near the maximum growth rate. And a small amount of load necessary for the growth for maintaining the microbial mass is given to make it a secondary reaction. The ratio of the load divided into the two reaction parts varies depending on the microorganism and the kind of the load to be applied, but in general, the reaction part 1 near the maximum substrate decomposition rate is 5 to 50% of the reaction part near the maximum growth rate.
It is a degree.

In the biological reaction near the maximum growth rate, if the growth corresponding to the decrease of the microbial cells in the reaction near the maximum substrate decomposition rate is carried out, the amount of microbial cells in the reaction system becomes constant and excess microbial cells do not occur, but the activity is activated. To do so, the microbial load may increase somewhat. For this reason, in an actual system, it is desirable to set the load amount and reaction time of the reaction section near the maximum growth rate so that the increase in the amount of microorganisms is minimized within the range where the activity is activated.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
1 to 3 are system diagrams showing different embodiments. In FIG. 1, 1 is a main reaction part, 2 is a separation part attached to this main reaction part, 3 is an activation multiplication part, and 4 is a separation part attached to this activation growth part. Most of the materials to be treated 5 such as fermentation raw materials and wastewater are introduced into the main reaction part 1, where biological reactions are carried out while maintaining the temperature conditions near the maximum substrate decomposition rate, and most of the substrates are converted as the main reaction. Disassemble. The reaction liquid is separated into a treated product 6a and a microbial body 7a in the separation unit 2,
The microbial body 7a is sent to the activated growth part 3. In the activation / proliferation part 3, the remaining portion 5a of the object to be treated is introduced to cause a biological reaction, and as a secondary reaction, the fed microorganism body 7a is activated and propagated. The reaction solution is separated into a treated product 6b and a microbial body 7b in the separation section 4, and the microbial body 7b circulates in the main reaction section 1. When the amount of microorganisms increases, it is discharged as surplus microorganisms 7c.

In FIG. 2, the separation part 2 is omitted, and the main reaction part 1 and the reaction liquid 8 are introduced into the activation multiplication part 3 as they are. Further, there are cases where all of the object 5 to be treated is introduced into the main reaction part 1 and cases where most of it is introduced into the main reaction part 1 and the remainder 5a is introduced into the activation multiplication part 3. Activated growth part 3 in reaction solution 8
If the required substrate is included in the main reaction part 1
You just have to install it. Other configurations and operations are similar to those in FIG. In the method of FIG. 2, the separating operations are integrated into one. Further, in the method shown in FIG. 2, the positions of the main reaction section 1 and the activation / proliferation section 3 may be exchanged, and the reaction liquid having undergone the activation / proliferation may be directly introduced into the main reaction section.

In FIG. 3, the first reaction section 9 and the second reaction section 10 are arranged in parallel, and the reaction near the maximum substrate decomposition rate and the reaction near the maximum growth rate are alternately performed. Then, separation is performed in the separation units 2 and 4, respectively, and processed products 6a and 6
However, in the reaction near the maximum substrate decomposition rate, the amount of microbial cells decreases, so that excess microbial cells 7c are not generated. Only in the reaction near the maximum growth rate, the amount of microbial cells increases. Excessive microorganism body 7c is generated.

In all of the above methods, the reaction near the maximum substrate decomposition rate is the main reaction, and most of the substrate is decomposed here, thereby increasing the substrate removal efficiency, and in the reaction near the maximum growth rate, a large load as a secondary reaction. It is possible to carry out mild growth without applying the strain, thereby reducing the increase of microbial cells and activating the activity.

The method of FIGS. 1 to 3 shows a general embodiment, and the basic configuration can be changed, and the detailed configuration can be freely selected. For example, the separation units 2 and 4 are shown as an accessory, but they may be independent,
Further, as the heating means and the temperature control means, commonly used means can be adopted. Furthermore, the present invention is widely applicable regardless of the type of microorganism, reaction method, field of use, and the like.

〔The invention's effect〕

According to the present invention, since the microorganisms are allowed to react in an environment where temperature conditions near the maximum substrate decomposition rate and temperature conditions near the maximum growth rate are repeated, the substrate decomposition efficiency is high, and The effect is that the increase can be significantly reduced.

Example of Invention

Anaerobic fermentation with methanogens was performed by the method shown in FIG. 2 using glucose as a substrate. Main reaction section 1 has a capacity of 50
The reaction temperature is 45 ° C. at 0 ml, the volume of the activation / proliferation part 3 is 500 ml, the reaction temperature is 35 ° C., and the COD concentration is 18,000 to 20,000 m.
g / raw water is the main load in the tank 7.2 to 8 kg COD / m ³ da
y, the reaction is carried out so that the residence time is 5 days in both parts, separated in a sedimentation tank with a capacity of 500 ml, and 0.05-0.1 ml / mi
All the microorganisms separated at the rate of n were circulated to the main reaction section.

As Comparative Example 1, the same raw water was injected into a reaction part having a capacity of 1 and a temperature of 35 ° C. so that a tank load was 3.6 to 4 kg COD / m ³ day and a residence time was 5 days, and a reaction by a conventional method was performed. Further, as Comparative Example 2, the same raw water was injected into a reaction part having a capacity of 1 and a temperature of 45 ° C. so that a tank load was 3.6 to 4 kg COD / m ³ day and a residence time was 5 days, and a reaction by a conventional method was performed.

After performing the above three series of reactions continuously for one month,
In Example and Comparative Example 1, the substrate could be decomposed continuously, but in Comparative Example 2, the gas generation stopped 5 days after the start of the reaction and the methane fermentation did not proceed thereafter. The results of these treatments are summarized in Table 1.

From the above results, in Comparative Example 2, no biological reaction continues, and in Comparative Example 1, the COD removal rate is low and the sludge increase rate is large in spite of the small tank load and the long residence time. In the examples, it can be seen that the COD removal rate is high and the sludge increase rate is extremely small even though the tank load is high and the residence time is short.

[Brief description of drawings]

1 to 3 are system diagrams showing another embodiment of the present invention. In each figure, the same reference numerals indicate the same or corresponding parts, 1 is a main reaction part, 2 and 4 are separation parts, 3 is an activation and multiplication part, 5 is an object to be treated, 6a and 6b are treated objects, 7a and 7b are Microbial body, 7c
Is a surplus microorganism body, 8 is a reaction solution, 9 is a first reaction part, and 10 is a second reaction part.

Continuation of the front page (51) Int.Cl. ⁵ Identification number Office reference number FI technical display location C12P 1/00 Z 2114-4B

Claims (4)

[Claims] 1. A biological reaction method for degrading a substrate by catabolic metabolism of a microorganism, characterized in that the reaction is carried out in an environment in which the microorganism is repeatedly subjected to temperature conditions near the maximum substrate decomposition rate and temperature conditions near the maximum growth rate. Biological reaction method. 2. The biological reaction method according to claim 1, wherein the reaction near the maximum substrate decomposition rate is the main reaction. 3. The biological reaction method according to claim 1 or 2, wherein the microorganism is circulated between the reaction part near the maximum substrate decomposition rate and the reaction part near the maximum growth rate. 4. The biological reaction method according to claim 1 or 2, wherein the reaction near the maximum substrate decomposition rate and the reaction near the maximum growth rate are alternately carried out in a plurality of reaction sections.