JPH0638957B2 - Wastewater treatment equipment - Google Patents

Description

TECHNICAL FIELD The present invention relates to a wastewater treatment apparatus using immobilized microorganisms.

(Prior Art) The activated sludge method is most popular for the treatment of municipal sewage and organic industrial wastewater. However, in this activated sludge method, the concentration of microorganisms per volume of the treatment equipment is low, and the treatment time is long, so that the equipment becomes large in size and requires a large area. In addition, there are many problems such as bulking development often occurring in the solid-liquid separation step after the treatment and generation of a large amount of excess sludge. On the other hand, a fixed-type processing device for adhering microorganisms to various carriers has been considered, and a dipping hearth method, a rotating disk method, and the like have been put into practical use. These utilize the phenomenon that microorganisms spontaneously adhere to the surface of a carrier to form a film, and it is possible to maintain a high concentration of microorganisms per unit volume of a processing apparatus, and to reduce the size of the processing apparatus. Also, solid-liquid separation is easy when the treatment is carried out stably. However, maintenance of the biofilm may be difficult because the biofilm may be peeled off or the biofilm may be difficult to produce due to a decrease in microbial activity, a change in treated water quality, or the like.

On the other hand, in the fields of pharmaceutical manufacturing and fermentation industry, a bioreactor method has been developed in which microorganisms are entrapped and immobilized in a resin or the like and used in the form of pellets or membranes, and in recent years it has also begun to be adopted in the field of wastewater treatment. In this method, since the microorganisms are previously cultured at a high concentration and immobilized, the concentration of the microorganisms can be arbitrarily increased to some extent.
Further, the immobilization stabilizes the biological activity, and the permissible range of treatment temperature, pH, etc. may be widened. Furthermore, since the cells are entrapped and fixed, solid-liquid separation is easy. Therefore, there is a feature that processing can be performed in a short time with a small processing device.

(Problems to be solved by the invention) Microorganisms to be immobilized are used by concentrating activated sludge obtained from general sewage treatment plants, or by culturing activated sludge as seed sludge in any artificial medium and separating it. By operation,
Highly concentrated microorganisms are obtained. In this case, when the composition of the wastewater to be treated is different from the composition of the artificial medium in which the microorganism is cultured, sufficient treatment efficiency may not be obtained.

Further, the treatment efficiency may decrease even when the quality of the wastewater to be treated changes. Furthermore, when the wastewater to be treated contains harmful substances or substances which are hardly decomposed, the treatment efficiency is significantly reduced.

Usually, as an immobilization carrier used for immobilization of microorganisms,
Alginic acid, k-carrageenan, acrylamide, photo-curable resin, etc. are known and have sufficient strength at the time of immobilization of microorganisms, but with the progress of treatment time, they are produced by the growth and metabolism of microorganisms. The carrier may expand and eventually collapse due to the influence of the generated gas and the components in the waste water. As a result, free microorganisms and carrier debris may flow out into the treated water, and the treated water quality may deteriorate.

An object of the present invention is to solve the above-mentioned problems of the prior art and to provide an apparatus for treating wastewater by immobilized microorganisms, which can efficiently perform treatment for a long period of time and can obtain good quality treated water.

(Means for Solving Problems) That is, according to the present invention, a part of raw water is introduced, an organic component in the raw water is used as a main substrate, and an appropriate microorganism corresponding to the raw water component is concentrated and cultured at a high concentration. And a culture tank for separating the obtained microorganisms, concentrated microorganisms, and a device for obtaining separated water,
An apparatus for treating wastewater, comprising: a device for entrapping and immobilizing the obtained concentrated microorganisms to obtain immobilized microorganisms, supplying the immobilized microorganisms to a treatment reactor, and returning the separated water to the first treatment reactor. When supplying the immobilized microorganisms, the deteriorated immobilized microorganisms in the first-stage treatment reactor are discarded, and when a new immobilized microorganism is filled, the first-stage treatment reactor filled with the new immobilized microorganism is It is characterized in that the order of inflow of wastewater into the treatment reactor can be changed so that the second-stage treatment reactor and the subsequent stages are positioned one stage before the last-stage treatment reactor.

(Operation) Next, the operation of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing an example of a wastewater treatment apparatus according to the present invention. In the present invention, a part of the raw water 8 is introduced into the culture tank 1, and suitable microorganisms corresponding to the components of the raw water are accumulated and cultured,
The obtained culture broth 13 containing microorganisms at a high concentration is introduced into the sedimentation / separation tank 2, where the culture broth is sedimented and separated to obtain concentrated microorganisms 14 and separated water 9. The concentrated microorganisms are sent to the microorganism immobilization tank 3 to produce the immobilized microorganisms. The obtained immobilized microorganisms are used in the first stage treatment reactor 4,
It is supplied to the second stage treatment reactor 5 and the third stage (final stage) treatment reactor 6, and the separated water 9 is returned to the raw water flowing into the treatment reactor. Part of the raw water 8 flows into the culture tank 1, where appropriate microorganisms corresponding to the components of the wastewater are integrated and cultured by using the organic components of the raw water as a main substrate. In addition, if necessary, a substrate such as glucose, acetic acid, etc., nitrogen, phosphorus inorganic salts yeast extract, etc. for assisting the culture of microorganisms, etc.
You may supply more. The first microorganisms to inoculate are:
General municipal sewage treatment sludge or industrial wastewater treatment sludge may be used, but if the wastewater to be treated is used in advance and microorganisms accumulated in a small scale are used, a quick start-up can be expected. When the raw water contains a hardly-decomposable substance, an appropriate amount of the hardly-decomposable substance is introduced into the culture tank from the nutrient tank 7, and a special strain that decomposes the hardly-decomposable material is cultured. By inoculating the tank 1, it is possible to deal with waste water containing hardly decomposable substances. The culture conditions of the microorganism in the culture tank 1 vary depending on the microorganism, but it is generally desirable that the temperature is 25 to 35 degrees Celsius and the pH is 6 to 8. In addition, when aerobic conditions are used, aeration is performed with air, oxygen, etc., and dissolved oxygen is supplied. Culture solution accumulated in the culture tank 1
13 flows into the sedimentation separation tank 2. In the sedimentation / separation tank 2, the culture solution 13 is allowed to stand and separated into separated water 9 and concentrated microorganisms 14. In order to carry out the separation, it is desirable that the microorganisms contained in the culture solution 13 are aggregated and settled in the form of activated sludge upon standing. Therefore, part of the concentrated microorganisms 14 is contained in the culture tank 1
Return to. By repeating this operation, the number of microorganisms that settle in the culture tank 1 increases, which in turn increases the concentration of microorganisms in the culture tank. The separated water 9 generated in the sedimentation separation tank 2 is mixed with the raw water 8 and flows into the treatment reactor.

Next, the concentrated microorganisms 14 obtained in the sedimentation separation tank 2 are sent to the immobilization tank 3. Here, it is entrapped in the polymer supplied from the polymer tank 15 to obtain an immobilized microorganism. Currently, as a polymer used for immobilization, a natural polymer, alginic acid,
Although k-carrageenan, agar, gelatin, albumin, and other synthetic polymers such as acrylamide and photocurable resins are known, any polymer may be used in the present invention. In addition, the shape of the immobilized microorganisms can be formed into a pellet shape, a sheet shape, a fiber shape or the like depending on the production method, and this can be arbitrarily selected depending on the structure of the treatment reactor.
The concentrated microorganisms 14 are mixed with the polymer supplied from the polymer tank 15 at an arbitrary ratio and sent to the immobilization tank 3,
Perform the immobilization reaction. A large number of fine pores are formed on the surface of the obtained immobilized microorganism, and the components in the raw water pass through these fine pores and diffuse inside. On the other hand, since the microorganisms immobilized inside cannot pass through these micropores, while metabolically decomposing the components in the raw water that are difficult to leak to the outside and diffused,
Retained in the carrier.

As described above, the concentration of microorganisms in the immobilized microorganisms can be arbitrarily selected according to the load amount of raw water, and by being included in the polymer, physical stability can be obtained and the buffering action of the polymer can be obtained. Therefore, the temperature range and pH range that can be handled are often widened. The obtained immobilized microorganism is supplied to the processing reactor. Various structures have been proposed as structures of bioreactors using immobilized microorganisms and immobilized enzymes. The fixed bed system includes a packed bed type, a membrane type, a tube type and a plate type, and the fluidized bed system includes a particle dispersion type and a plate type. Furthermore, an ultra-reactor over-membrane type by combining with a separation membrane has been devised. Immobilized microorganisms have sufficient strength immediately after the immobilization reaction, but as the treatment time elapses, the carrier expands due to the effects of gas generated by metabolism and components in raw water, and the carrier will eventually collapse. There is. Therefore, by connecting a plurality of treatment reactors and performing multi-stage treatment, the load applied to the treatment reactor of the subsequent stage is reduced, the expansion of the carrier of the treatment reactor of the succeeding stage is reduced, and the inflow from the preceding stage is released. It is effective to capture microorganisms and debris of the carrier in the treatment reactor in the subsequent stage.

As a feature of the present invention, when supplying the immobilized microorganisms to the treatment reactor, the deteriorated immobilized microorganisms in the first-stage treatment reactor are discarded in consideration of the above points, and sufficient strength immediately after immobilization is obtained. It is possible to load the immobilized microorganisms, make this treatment reactor the final treatment reactor, and sequentially shift the inflow order so that the second stage treatment reactor and the subsequent stages are positioned one stage forward.

FIG. 1 is an example of a three-stage process in which three process reactors are connected. At the start of treatment, the raw water 8 flows into the No. 1 treatment reactor 4, which is the first stage treatment reactor,
Most of the components to be processed are processed here. Second then
It flows into the No. 2 treatment reactor 5 which is the stage treatment reactor, and finally into the No. 3 treatment reactor which is the final stage treatment reactor. In the second-stage and final-stage treatment reactors, the components to be treated that could not be treated in the first stage are treated and discharged as treated water 12. No. 1 processing reactor 4, which has the largest load as the processing time elapses
The immobilized microorganisms in the inside deteriorate, expand, and begin to collapse,
The liberated microorganisms, carrier debris, etc. become mixed in the effluent. However, while passing through the No. 2 treatment reactor 5 and the No. 3 treatment reactor 6, the liberated microorganisms, carrier debris, etc. are captured, and the quality of the treated water 12 does not deteriorate. When the immobilized microorganisms in the No. 1 treatment reactor 4 are severely deteriorated, the immobilized microorganisms in the reactor are discarded and the immobilization tank 3 is obtained. Fill with the immobilized microorganisms. At this point, the inflow path of the raw water 8 is switched to first flow into the No. 2 treatment reactor 5. Next, it flows into the No. 3 treatment reactor 6, finally flows into the No. 1 treatment reactor 4, and is discharged as treated water 12. here
No.2 processing reactor 5 is
o.3 Processing reactor 6 is the second stage processing reactor, No.
This means that the 1-treatment reactor 4 is sequentially displaced from the final-stage treatment reactor.

Similarly, when the immobilized microorganisms in the No. 2 treatment reactor 5 are deteriorated, the deteriorated immobilized microorganisms are discarded, the newly obtained immobilized microorganisms are filled, and the raw water 8 is
It flows into the No. 3 treatment reactor 6, then into the No. 1 treatment reactor 4, finally into the No. 2 treatment reactor 5, and is discharged as treated water 12.

As described above, the deteriorated immobilized microorganisms are discarded, and the treatment reactor filled with the newly obtained immobilized microorganisms is used as the final stage treatment reactor to prevent deterioration of the treated water quality, and as the second stage treatment reactor, Bear a moderate load,
Effective treatment can be performed by using the treatment reactor in which the microorganisms in the carrier grow and the activity of the immobilized microorganisms becomes large as the first stage treatment reactor. Although a small amount of surplus sludge 11 is generated from each treatment reactor, a part of the sludge is returned to the culture tank 1 as return sludge 10 and the rest is discharged outside the system.

(Effects of the Invention) As described in detail above, according to the present invention, the following effects can be obtained.

(1) By setting the treatment reactor filled with new immobilized microorganisms at the final stage, it is possible to capture the floating microorganisms and carrier debris flowing in from the previous stage, and the quality of the treated water is good.

(2) When the immobilized microorganisms in the first-stage treatment reactor are recharged with new ones due to the deterioration of the immobilized microorganisms,
Until now, the first stage treatment reactor was used as the final stage to prevent deterioration of the treated water quality, and the order of the wastewater inflow to the treatment reactor was changed so that the second stage treatment reactor and the subsequent stages were positioned one stage before the other stage. As a result, the stabilization of the treatment can be achieved by using the second-stage treatment reactor in which the activity of the immobilized microorganisms has increased during that period as the first-stage treatment reactor into which the raw water with the largest load flows.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an example of an apparatus according to the present invention. In the figure, 1: culture tank, 2: sedimentation separation tank, 3: immobilization tank, 4: first stage treatment reactor, 5: second stage treatment reactor, 6: third stage treatment reactor, 7: nutrient tank 8: raw water , 15: Polymer tank.

Claims (1)

[Claims] 1. In a wastewater treatment apparatus for performing a multi-stage treatment by connecting a plurality of treatment reactors filled with immobilized microorganisms, a culture tank in which a part of raw water is introduced and the microorganisms are accumulated and cultured, and the accumulated microorganisms are cultured. Equipped with a device for separating concentrated microorganisms and separated water, and a device for entrapping and fixing the concentrated microorganisms to obtain immobilized microorganisms, returning the separated water to the first-stage treatment reactor, and supplying the immobilized microorganisms to the treatment reactor A waste water treatment apparatus for supplying the immobilized microorganisms, when the deteriorated immobilized microorganisms in the first-stage treatment reactor are discarded and new immobilized microorganisms are filled,
It is possible to change the order of inflow of wastewater into the treatment reactor so that the first-stage treatment reactor filled with the new immobilized microorganism is located in the final-stage treatment reactor and the second-stage treatment reactor and the subsequent stages are located in the preceding stages one by one. Wastewater treatment equipment.