JPH02207787A - Inclusive immobilized micro-organism - Google Patents

Abstract

PURPOSE:To secure larger space of micro-organism multiplication in polymer gel by sealing a micro-organism used for micro-organism treatment and a solid material of fine particles having properties of being dissolved during the micro- organism treatment. CONSTITUTION:A concentrated solution of micro-organism to be used for micro- organism treatment, obtained by pure culture or trained culture is sufficiently blended with a given amount of a fine particulate solid material having properties of being gradually dissolved during the micro-organism treatment and 10-300mu particle diameter. Then the blend is mixed with an aqueous solution of polymer gel material such as PVA or polyacrylamide to give a mixture of the micro-organism and the polymer gel material containing fine particles of the solid material. Then the mixture is frozen, gelatinized and then iced materials such as coexisting water are melted to give bulk of inclusive immobilized micro-organism. Consequently, a greater amount of micro-organisms can be retained than by a conventional procedure and organisms can be efficiently treated.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention is directed to the use of microorganisms used in so-called microbial treatment, typified by the microbiological treatment of water such as sewage water or tap water, in a polymer gel. This invention relates to the improvement of entrapped and immobilized microorganisms.

<Prior art> A method for microbiologically removing pollutants such as organic substances and inorganic nitrogen compounds contained in wastewater such as sewage and industrial wastewater, or relatively polluted water such as river water. As one example, the comprehensive immobilization microbial method has recently attracted attention.

The comprehensive immobilization microorganism method encapsulates and immobilizes the microorganisms involved in the removal of the contaminants in a so-called polymer gel that does not penetrate the microorganisms but allows the contaminants dissolved in water to pass through. This is a method of performing microbial treatment using entrapped immobilized microorganisms, for example, in which the immobilized microorganisms are filled into a fixed bed type or fluidized bed type glue actor to treat water to be treated.

In this method, a target microorganism or a group of microorganisms containing a relatively large amount of target microorganisms, obtained by culturing or acclimatization in advance, are encapsulated in a polymer gel and immobilized in an irremovable state. Perform processing. Therefore, the target microorganisms can be retained in a relatively large amount within the treatment system, and in so-called floating microbial treatment methods such as ordinary activated sludge treatment, a large amount of the target microorganisms can be retained within the system. It is particularly suitable for water treatment using microorganisms that are difficult to control, have a slow growth rate, or microorganisms with weak floc-forming ability, and has the advantage of being able to perform efficient treatment even in such cases.

In addition, the problems that tend to occur in floating microbial treatment methods,
Another advantage is that it is extremely easy to separate microorganisms from treated water after treatment.

As a polymer gel material for comprehensive immobilization of microorganisms,
Generally, synthetic polymers such as polyvinyl alcohol (PVA), polyacrylamide, and photocurable resins, or natural polymers such as sodium alginate and K-carrageenan are used. When immobilizing microorganisms using these polymer gel materials, the polymer gel material before gelling and the microorganisms to be immobilized are mixed, and then the mixture is gelled by an appropriate method to form a sphere. , we have produced entrapping immobilized microorganisms in the shape of horns, etc.

For example, when using PVA as a polymer gel material, a mixture of PVA aqueous solution and microorganisms is placed in a suitable container, frozen to form a gel, and then the coexisting ice bodies such as water are melted and the remaining The entrapping immobilized microorganisms are created by shredding the gel (PVA-freezing method), or by dropping a mixture of PVA aqueous solution and microorganisms into a boric acid solution to form a gel (PVA-boric acid). There are known methods to do this.

<Problems to be solved by the invention> However, in the conventional entrapping immobilized microorganism method as described above, entrapping immobilized microorganisms in which only microorganisms are encapsulated within a polymer gel are used. There is a problem in that the space in which microorganisms can grow is limited, and therefore the amount of microorganisms retained within the polymer gel cannot be increased very much. As a result, a problem arises in that the volumetric load in the reactor cannot be made very high.

The present invention solves the above-mentioned problems, and is capable of securing more space for microorganisms to grow within the polymer gel than before, and therefore enables more efficient water treatment than before. The purpose is to provide biochemical microorganisms.

Means for Solving the Problems> The present invention, which was made to solve the above problems, combines microorganisms used in microbial treatment and fine particulate solids that have the property of dissolving during microbial treatment into a polymer gel. It is an entrapping immobilized microorganism characterized by being enclosed in a material.

<Effect> Below, microorganisms involved in the reaction of decomposing ammonia nitrogen (NH4-N) in water and nitrifying it to nitrate nitrogen (No, -N), that is, nitrifying bacteria, are comprehensively immobilized by the PVA-freezing method. The present invention will be described in detail by taking a case in which:

FIG. 1 is a block diagram showing an example of the method for producing entrapping immobilized microorganisms of the present invention. However, in a culture system in which nitrifying bacteria are the dominant species (for example, microorganisms in an already operating nitrification equipment), for example, calcium carbonate (Ca
A predetermined amount of a finely divided solid substance, such as COz), which preferably has a property of gradually dissolving during microbial treatment, is added and thoroughly mixed. Next, this is processed, for example, to a polymerization degree of 500 to
1 of PVA with a saponification degree of 70% or more at 3,000%
Mix with 0-30% (wt) aqueous solution, c a c O3
Nitrifying bacteria (microorganisms) and pVA (
(polymer gel material) to obtain a mixture. The mixture is placed in a suitable container and frozen at a temperature of -20°C or lower for a predetermined period of time to gel the PVA, and then the ice bodies such as coexisting water are melted at room temperature to combine the nitrifying bacteria and the above. A mass of entrapping immobilized microorganisms is obtained in which the solid matter is encapsulated with PVA gel.

Inside the entrapping immobilized microorganism thus obtained, in other words, inside the polymer gel, the added Ca CO3 fine particles are encapsulated in fine particle form together with the nitrifying bacteria. This is because CaCO3 is a poorly soluble substance in neutral or alkaline water, and hardly dissolves even during the above operation. And the trapped caco
The sa particles exist within the polymer gel with nitrifying bacteria attached to them or in combination with nitrifying bacteria.

Next, the obtained mass of entrapping immobilized microorganisms of the present invention is washed with water, and then shaped into cubes of about 3 day squares by shredding or the like, and subjected to nitrification treatment of wastewater or the like.

Encapsulatively immobilized microorganisms of the present invention obtained as described above (
When treated water containing NH4-N is treated using nitrifying bacteria (in this case, nitrifying bacteria), the CaCOs fine particles contained in the immobilized microorganisms together with the microorganisms gradually dissolve in the treatment system.

This is because, as mentioned above, CaC0 is poorly soluble in neutral or alkaline water, but has the property of being soluble in acidic water. On the other hand, the nitrification reaction is a reaction that requires alkali in the process, so in the nitrification process, the alkali in the system is consumed, and the pH in the system becomes 1. In particular, the pH in the polymer gel that immobilizes the nitrifying bacteria becomes acidic. easy to become,
Therefore, the CaCoza particles encapsulated in the polymer gel gradually dissolve.

After the cacos fine particles are dissolved in this manner, a space is created in that part. Of these spaces, the spaces created by the dissolution of CaC01 particles adhering to nitrifying bacteria or bonding with nitrifying bacteria are naturally used effectively as growth spaces for nitrifying bacteria, and as a result, the unit volume It is now possible to hold more nitrifying bacteria than before in the entrapping immobilized microorganisms, in other words, within the polymer gel, and therefore it is possible to perform nitrification treatment more efficiently than with conventional entrapping immobilized microorganisms.

In the above-described embodiment of the method for producing entrapping immobilized microorganisms of the present invention, as a procedure for causing CaCO3 fine particles to coexist in a mixture of nitrifying bacteria as microorganisms and PVA as a polymeric material, first, nitrifying bacteria and CaCO , fine particles were mixed, and then the PVA aqueous solution was mixed.
The procedure for making CaCO3 particles coexist is not limited to this, and there are no options; for example, CaCOs particles and PVA may be mixed at the same time, or CaCOs particles and PVA may be mixed first, and then nitrifying bacteria may be mixed. You can do it like this.

The solid substances used in the present invention that have the property of being soluble during microbial treatment include those that are poorly soluble in neutral or alkaline water but soluble in acidic water, such as the above-mentioned CaCO5, or those that have the property of dissolving in acidic water. It is preferable to use a material that has a property of gradually dissolving, that is, a material that has low solubility in water and does not inhibit the activity of microorganisms when dissolved. For example, the above Ca CO
Solid substances other than s include magnesium carbonate (MgCO
l), calcium phosphate (Ca s (P 04) z
), hydroxyapatite phosphate (Ca s (OH)
(PO2), barium carbonate (p, aCO), etc. can be used, and furthermore, ores containing these substances as main components can also be used.

In addition, the particle size of the solid material is not preferable because if the particle size is too large, the space created by dissolution will become large and reduce the physical strength of the entrapping immobilized microorganisms (and if the particle size is too small) This is also undesirable because the resulting space is smaller than the size of the microorganism (usually about 1μ), making it impossible for microorganisms to grow.
It is best to use a 300μ thick one.

Further, the amount of solid matter to be added is preferably 5 to 50% by weight based on the polymer gel material used.

In addition, in the above-mentioned embodiment, an example was explained in which nitrifying bacteria were used as the microorganism and PVA was used as the entrapping polymer gel material, but the present invention is not limited to this, and it can be used in general use in water treatment. It can be applied to any microorganism, including microorganisms such as It can be used.

<Example> The present invention will be explained in detail below.

A solution containing nitrifying bacteria (not a pure culture system of nitrifying bacteria, but in which nitrifying bacteria are the dominant species) that has been acclimated with a substrate containing ammonium chloride as a main component is centrifugally concentrated to an MLSS concentration of 40.00.
Add 25 g of fine particulate CaCOs (commercially available powdered CaCO, reagent used as is) with an average particle size of 10 μm to a concentrated solution of nitrifying bacteria 5 Qmj2 with a concentration of 0 μ/l, mix thoroughly, and then Degree of polymerization 1,700-2,4
00, 75ml of 20% aqueous solution of PVA with 100% saponification degree
j+ was added and mixed again. The resulting mixture was placed in a container, frozen at -50°C for 24 hours to form a gel, and then thawed at room temperature to obtain a mass of entrapping immobilized microorganisms.

The resulting mass of entrapping immobilized microorganisms was thoroughly washed with tap water and then shredded into cubes with 311 sides. The entire amount of entrapping immobilized microorganisms thus produced was filled into an experimental fluidized bed type glue reactor as shown in FIG. 2, and the following nitrification experiment was conducted using the reactor.

That is, the prepared entrapment-immobilized microorganism 1 is placed in the acta 2, and NH4-N is contained at 50 μ/l, and in addition, P Oa
P 1 rair/j! and N a HCO
Synthetic water 3 containing z 600■/l is continuously introduced,
At the same time, air was introduced from an aeration method 4 attached to the bottom of the reactor 2 through an air introduction pipe 5 communicating with the aeration method 4. The synthetic water 3 was nitrified while the entrapped immobilized microorganisms 1 were fluidized by aeration caused by the introduction of the air, and the treated water 6 was caused to flow out of the reactor 2 by overflow. In FIG. 2, reference numeral 7 indicates a baffle plate for preventing the entrapment-immobilized microorganisms 1 from overflowing to the outside of the reactor 2 together with the treated water 6.

The above-mentioned nitrification experiments were continued, and the residual NH4-N concentration in the resulting treated water was appropriately measured. /d・day) was calculated. The relationship between the nitrification rate and the number of days elapsed at this time is shown in the graph of FIG. 3 by a solid line.

As a comparative example, 5 Q ml of a concentrated solution of nitrifying bacteria was
Add 25 ml of tap water instead of adding Ca CO:l (
A conventional entrapping immobilized microorganism was prepared in exactly the same manner as in the example except that about 25 g) was added and mixed with the PVA aqueous solution, and a nitrification experiment similar to that in the example was conducted using the immobilized microorganism. The relationship between the nitrification rate and the number of days elapsed at this time is shown in the graph of FIG. 3 by the dotted line.

As shown in FIG. 3, in the case of the example, approximately 3
Although the nitrification rate still tends to increase even after 5 days have elapsed, in the case of the comparative example, the nitrification rate reaches a nearly constant value after about 35 days.

The nitrification rate at this time in the comparative example was approximately 0°7.
kg-N Ha N/n? - Days, whereas in the example it is already about 1.6 kg-N Ha
The nitrification rate reached N/rrr·day, which is more than twice that of the comparative example. In other words, when using the entrapping immobilized microorganism of the present invention, it is possible to perform treatment with a volume load that is more than twice as large as when using the conventional entrapping immobilized microorganism, and therefore the equipment can be used accordingly. It can be made compact.

<Effects> As explained above, the entrapping immobilized microorganism of the present invention confines the microorganism used for microbial treatment and fine particulate solid matter having the property of dissolving during the microbial treatment within a polymer gel. When the entrapping immobilized microorganism of the present invention is used for water treatment, the solids are gradually dissolved in the treatment system, making it possible to create more space in the polymer gel than before. Naturally, microorganisms proliferate in this space, and as a result, more microorganisms can be retained in the enclosing immobilized microorganisms per unit volume than before, making it possible to carry out efficient biological treatment. It becomes possible to do so.

[Brief explanation of the drawing]

FIG. 1 is a block explanatory diagram showing an example of the method for producing entrapping immobilized microorganisms of the present invention, FIG. 2 is a schematic diagram of a fluidized bed reactor used in Examples and Comparative Examples, and FIG. is a graph showing the relationship between the number of elapsed days and the nitrification rate in Examples and Comparative Examples, where the horizontal axis shows the number of elapsed days and the vertical axis shows the nitrification rate. 1... Comprehensive immobilized microorganisms 2... Reactor 3...
・Synthetic water 4...Aeration method 5...Aeration pipe 6...Treated water 7...Baffle plate Figure 2 Figure 3 Number of elapsed days (days)

Claims (1)

[Claims] 1. An entrapping immobilized microorganism characterized in that microorganisms used for microbial treatment and fine particulate solid matter having a property of dissolving during microbial treatment are encapsulated in a polymer gel material.