JPH0316695A - Biological treating device for waste water - Google Patents

Abstract

PURPOSE:To maintain the sufficient quantity of microorganisms in a tank even in a low load region and to prevent the unnecessary stripping of the microorganisms formed on the surface of carriers by using pumice suitable for sticking of the microorganisms as the carriers of aerobic and anaerobic fluidized beds. CONSTITUTION:The org. matter in the waste water is aerobically decomposed by the aerobic microorganisms sticking to the pumice 5 which is the carrier in a reaction column section 3. The waste water rising in the reaction column section 3 is supplied to a carrier separating section 4. The pumice 5 and bubbles are separated by a separating cylinder 12 in the carrier separating section 4. The waste water is transferred through a weir 13 on the outer periphery to a circulating tank 7. The waste water in the tank 7 is partly sent to a settling chamber 14 where solids are settled and separated and final treated water 15 is obtd. The pumice 5 consists of recesses 17 which are suitable for the sticking of the microorganisms and protect the microorganisms from stripping by the collision of the carriers and fine pores provided over the entire surface, i.e., pockmark parts 16. The sufficient quantity of the microorganisms is maintained in the column part 3 even in the low load region.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for biologically treating wastewater containing organic matter such as urban wastewater and industrial wastewater.

[Conventional technology]

Currently, the treatment of urban wastewater, industrial wastewater, etc. is mainly carried out by the activated sludge method.

However, this method has problems in that it requires a large treatment area and a large amount of aeration power, and in recent years aerobic and anaerobic fluidized beds have been attracting attention as methods that can solve these problems.

The above fluidized bed treatment method involves filling a tank with carriers, fluidizing the carriers with upward flow and blown air (in aerobic cases), and decomposing organic matter in the wastewater by microorganisms naturally occurring on the carrier surface. It is something to do.

Therefore, in this fluidized bed treatment method, the selection of the carrier is a very important factor in determining the performance of the fluidized bed.

Conditions that the carrier must satisfy include adhesion of microorganisms and strength.

Generally, porous materials with a pore diameter of about 10 microns are considered to have good adhesion, and depending on the strength, zeolite, spherical activated carbon, etc. are used.

The surfaces of these carriers are finely porous, and if kept in a static state, conditions are suitable for the attachment of microorganisms.

[Problem to be solved by the invention]

However, with the above-mentioned conventional carriers, there is a problem that in an aerobic fluidized bed, the inside of the tank is in a state of intense agitation due to the upward flow and blown air, and the attached microorganisms are peeled off due to collisions between the carriers.

Micropores of several tens of microns are suitable for microorganisms to enter and adhere to them, but the amount of microorganisms that can be retained within the micropores is extremely small. The amount of microorganisms present in the pores is insufficient to remove organic matter.

In order to maintain a sufficient amount of microorganisms for treatment with such carriers, it is necessary for the microorganisms attached to the pores to proliferate and form a biofilm over the entire surface, but as mentioned above, collisions between the carriers This causes microorganisms to detach and prevent biofilm formation. This phenomenon becomes a problem particularly when the volumetric load on the fluidized bed is small, for example when high-level processing is performed in the fluidized bed. Also, it takes a long time to start up the fluidized bed. Furthermore, since the microorganisms are unnecessarily removed, the number of microorganisms increases in the treated water, leading to deterioration of the quality of the treated water.

In the case of an anaerobic fluidized bed, there is no need for blown air, so stirring is gentle, but since anaerobic bacteria grow slowly, separation due to carrier collision during startup becomes a more important problem.

Generally, anaerobic fluidized beds are said to require several months to start up, and how to shorten this time is an important issue in the development of anaerobic fluidized beds.

Furthermore, among the above-mentioned carriers, zeolite, which is commonly used, has a problem in strength, and there is a concern that the carrier may become fine and run out.

The present invention was developed in consideration of the above, and it is possible to maintain a sufficient amount of microorganisms in the tank even in a low load area, and it is possible to prevent unnecessary detachment of microorganisms generated on the surface of the carrier. Deterioration of the quality of treated water can be prevented,
Furthermore, to provide a biological treatment device for wastewater that can prevent peeling during start-up, shorten the number of days required for start-up, and further eliminate cracking and pulverization of the carrier, thereby extending its lifespan. The purpose is to

[Means to solve the problem]

In order to achieve the above object, the present inventors conducted a detailed study on the shape of the carrier, and found that it has pores of approximately several tens of micrometers that encourage the attachment of microorganisms, as well as pores that protect microorganisms from collisions with the carrier. We came up with the idea that a carrier with larger recesses that serve as hideouts is optimal as a microbial adhesion carrier. Furthermore, as a result of investigating the surface structure of various granules, it was found that pumice granules have such 2ffi
It was discovered that the carrier has a structure, that is, a combination of large recesses and pores, and is also excellent in strength.

From this, the biological treatment device for wastewater according to the present invention has the following features:
This system is characterized by using pumice as a carrier to be filled into the fluidized tank.

[For production]

In the treatment of wastewater using a fluidized bed, microorganisms adhere to and proliferate on the surface of pumice, which is a carrier, and are retained in the recesses of the carrier.

〔Example〕

A tip embodiment of the present invention will be described based on the drawings.

FIG. 1 shows an example of an aerobic three-phase fluidized bed, and this device can be roughly divided into:
It consists of a dispersion section 2, a reaction force ram section 3, and a carrier separation section 4. Then, in the reaction column section 3, a particle size of 0.25 to 0.
．． Pumice stone 5 of 27 mm was filled at a volume ratio of 25%.

The dispersion section 2 of the fluidization tank 1 is supplied with waste water, in this case treated water from an existing treatment device, through a supply bomb 6, and circulating water from a circulation tank 7 through a circulation bomb 8, respectively. Then, this supply water passes through the outlet 9 and flows into the reaction force ram N3. The inside of this reaction force ram section 3 is aerated with air from a blower 11 through an aeration pipe 10, and the carrier is fluidized by this aeration and the above-mentioned waste water. In this reaction cam section 3, organic matter in the waste water is aerobically decomposed by aerobic microorganisms attached to pumice 5, which is a carrier. Pumice 5 and air bubbles are separated from the waste water that has ascended through the reaction force ram section 3 by a separation tube 12 installed in the carrier separation section 4, and then transferred to the circulation tank 7 through a weir 13 on the outer periphery. A part of the waste water in the circulation tank 7 is sent to the sink #Wjl4 as treated water of the fluidized bed, where solids are separated by precipitation, and the final treated water 15 is obtained.

Table 1 shows the treatment results of the treated water obtained at each stage as described above. Note that SS in the table indicates detached microorganisms.

As shown in FIG. 2, the surface of the pumice stone 5 used as the carrier has relatively large stripes with convex portions 16 having pock-like fine pores of about 10 μm, and the surface has pock-like fine pores as described above. It has a two-stage surface structure of recesses 17 having holes.

After the treated water has been treated, the surface of the pumice stone 5 becomes as shown in FIG.
is retained. This shows good processing characteristics even in short retention periods. Moreover, no cracking or pulverization of the carrier (pumice 5) was observed two months after the start of operation.

In addition, although the above embodiment shows a case of a circulating tank configuration, it is also possible to draw circulating water directly from the upper part of the device. Depending on the conditions, it is also possible to fluidize the carrier using supplied water and air without using a circulation pump. Further, here, the diameter of the carrier used was 0.25 to 0.27n+, but this does not impose any restrictions, and the optimum diameter should be selected depending on the amount of microorganisms attached.

Although an aerobic three-phase fluidized bed is shown here, it is also applicable to a draft tube type fluidized bed. Furthermore, it is also possible to use pumice 5 as a carrier for an anaerobic fluidized bed. In this case, since the microorganisms adhering to the striped recesses 7a are protected from collisions between the carriers, the start-up period can be shortened even for anaerobic microorganisms with a slow growth rate.

Table 1 Table 2 Note that the pumice 5 used in the above example is natural pumice (dried rock natural glass), which is made up of small particles and sand, and the topsoil etc. are completely removed by sieving by washing with water and stirring. Drying is done in a cylindrical furnace,
The particles were classified by particle size using a vibrating sieve.

Further, the standard composition of this pumice stone 5 is shown in Table 2.

Moreover, the specific gravity of this is 0.59 to 0.9.

〔Effect of the invention〕

According to the present invention, as a carrier for aerobic and anaerobic fluidized beds, the four parts 17 are suitable for attachment of microorganisms and protect the microorganisms from peeling off due to collision of the carrier, and the fine pores, that is, the pocked parts, have over the entire surface. By using the pumice stone 5 which has a double structure surface condition, it is possible to maintain a sufficient amount of microorganisms in the tank even in a low load range, and it is possible to prevent unnecessary detachment of microorganisms generated on the carrier surface.
It can prevent the quality of treated water from deteriorating due to detached microorganisms, and furthermore, it can prevent detachment during start-up, shorten the number of days required for start-up, and eliminate the cracking and fragmentation of the carrier, extending its life. be able to.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of the configuration of an aerobic Sanwa fluidized bed type wastewater treatment apparatus, FIG. 2 is an enlarged sectional view of pumice, and FIG. 3 is a plan view of pumice used as a carrier. 1 is a fluidized tank, 2 is a dispersion section, 3 is a reaction force ram section, 4 is a carrier separation section, 5 is a pumice stone, 16 is a pocked section, and 17 is a recessed section.

Claims (1)

[Claims] The use of pumice as a carrier in a fluidized bed type biological wastewater treatment device that biologically treats wastewater in the tank by flowing a granular carrier in the tank and generating a microbial film on the surface of the carrier. A biological treatment device for wastewater.