JPH06106198A - Method and device for microbiological reduction of amount of surplus sludge - Google Patents

Abstract

PURPOSE:To obtain a bacteriolytic action without the need of any special auxiliary equipment and a method for reducing the amt. of surplus sludge through recycling of bacteria by a method wherein the surplus sludge discharged from a process for biological treatment of dirty water is inoculated with one or more strans of the slime bacteria having a bacteriolytic action and the surplus sludge is subjected to the action of the bacteria in an aerobic condition. CONSTITUTION:The method for microbiological reduction of the amt. of surplus sludge includes introducing surplus sludge 4 from a microbiological treating tank into a surplus solid concn. tank 2 to concentrate the same to about 20,000-30,000mg/l; thereafter sending the surplus sludge 4 into a sludge amt. reducing tank 3; inoculating the surplus sludge 4 in the sludge amt. reducing tank 3 with a biomass 12 consisting of one or more strains of the slime bacteria having a bacteriolytic action on the surplus sludge 4 by using any one of supply means such as shower, sprayer, injector and simple pipe; and subjecting the surplus sludge 4 to the action of the inoculated bacteria for 3-5 days at a normal temp. of around 25 deg.C in an aerobic condition, whereby the surplus sludge 4 is bacteriolyzed, the slime bacteria is reconstructed by assimilation and the amt. of the surplus sludge 4 is reduced due to a loss entailed by the respiration of the bacteria.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention has a bacteriolytic action that allows surplus sludge generated in the course of microbiologically treating wastewater such as human waste, sewage and / or organic wastewater to be widely distributed in nature. The present invention relates to a microbiological weight reduction method for excess sludge that is reduced by slime bacteria.

[0002]

2. Description of the Related Art Conventionally, excessive sludge generated from biological treatment of human waste, sewage and / or organic wastewater, particularly aerobic biological treatment, has a huge amount of generation.
The processing and disposal of them requires consumption of large amounts of energy and resources.

Currently, there are about 1, 2 human waste treatment sites in Japan.
00 places, sewage treatment plant (urban sewage) is 800-1, 00
There are 0 places, and even if the treatment of organic wastewater is excluded, the amount of surplus sludge to be treated and disposed of will be enormous. Although some of these excess sludges are effectively used, most of the excess sludges are concentrated and the dehydration auxiliary is added to the excess sludges to dehydrate them by mechanical means or method to obtain a water content of 80 to 85%. And then
A large amount of energy and resources for incineration in an incinerator are input and treated and disposed of. However, as the amount of surplus sludge increases, the facility for concentrating and dehydrating is inevitably increased in size, and the dehydration rate is also limited, and the incinerator is required to process a large amount. For this reason, each local government is not only struggling with the economic burden of treatment / disposal, but also from the perspective of technical measures against secondary pollution such as air pollution and water pollution, and global warming. Are being asked for a solution.

Therefore, a method for reducing the amount of excess sludge generated has been sought. For example, in sewage treatment, etc., excess sludge and first settling basin (hereinafter referred to as “first settling”) are each concentrated and then mixed at a generation rate, and methane fermentation (anaerobic digestion) is applied to reduce excess sludge. Has been. However, since surplus sludge is, as it were, surplus bacterial cells of activated sludge microorganisms, the decomposition rate of the cell walls and cell membranes of the bacterial cells is poor in ordinary methane fermentation treatment, and it takes about 20 to 30 days for digestion days, which is required for the equipment. Requires excessive investment in maintenance.

On the other hand, a microbiological method for destroying cell walls and cell membranes of cells without depending on digestion has been investigated. For example, Japanese Unexamined Patent Publication No. 61-129098 proposes a method of adding bacteriophage to sludge generated by biological treatment of wastewater, and reducing the amount of sludge by the bacteriolytic action. However, bacteriophages are extremely host-specific, and certain bacteriophages parasitize and lyse only certain bacteria. Therefore, when trying to reduce the amount of sludge in a mixed culture system of multiple bacterial species such as activated sludge with bacteriophage, practically the same number of types of bacteriophage as the bacterial species inhabiting activated sludge are screened from the natural world and formulated. It is necessary to apply this method to sludge reduction.

Furthermore, the destroyed bacterial contents are released into water, which causes new organic pollution. In the above-mentioned patent publication, the organic matter released seems to be bacteriophage, but the virus containing bacteriophage is an extremely minute particle of colloidal level, as it was called a filterable pathogen in the old days, and it can be separated by solid-liquid separation. Removal is not easy. In the patent publication, the separated water that has been subjected to solid-liquid separation is discharged, but it is clear that a large number of bacteriophages are contained in this and this becomes a new contaminant. On the other hand, it is easy to think of introducing some kind of purification device,
When it is returned to the biological treatment process, the activated sludge is inoculated with a bacteriophage solution having an extremely high lytic power, which may impair the treatment.

Therefore, a means for treating bacteriophage must be provided, but as described above, the virus has a colloidal size, and it is not possible to carry out the usual precipitation and separation, and it is also possible to use the usual filtration method. Separation is difficult,
It is necessary to separate by ultrafiltration or reverse osmosis filtration equipment. Alternatively, inactivating / sterilizing means must be provided, and in some cases, a disinfection device for the disinfectant used therefor is also required. As a result, the number of ancillary facilities is enormous and it is extremely difficult to put them to practical use.

[0008]

SUMMARY OF THE INVENTION It is an object of the present invention to develop a sludge reduction method and a sludge reduction device suitable for the method, which does not require special incidental equipment, by lysing and reutilizing microorganisms. .

[0009]

[Means for Solving the Problems] In order to achieve the purpose of reducing sludge, the present inventors have used surplus sludge by a lytic enzyme produced outside mycelia by myxobacteria, which are in general distribution in nature. The present invention has been made paying attention to the action of lysing bacterial cells such as BOD-assimilating bacteria, which is the main constituent bacterium, and assimilating them to self-cell construction. That is, the above-mentioned object is achieved by the development of the method and apparatus for reducing the amount of surplus sludge by the present invention. 1) Microbiological weight loss of surplus sludge, which is characterized by inoculating surplus sludge discharged from the biological treatment process of wastewater with a single strain or multiple strains of myxobacteria having a bacteriolytic action and operating under aerobic conditions. Method. 2) The excess sludge discharged from the biological treatment process of sewage is inoculated with a single strain or multiple strains of myxobacteria having a bacteriolytic action, and a weight reduction process in which the strains are allowed to act under aerobic conditions, and a waste reduction process is performed. A method for microbiologically reducing excess sludge, comprising the step of solid-liquid separating the reduced sludge, and recycling a part of the solid-liquid separated separated sludge to the reducing step. 3) The excess sludge discharged from the biological treatment process of wastewater is inoculated with a single strain or multiple strains of myxobacteria having a bacteriolytic action, and the sludge is discharged from the reduction process and the reduction process in which it is allowed to act under aerobic conditions. Microorganisms of excess sludge characterized by having a step of solid-liquid separation of the reduced sludge, and circulating and returning part of the solid-liquid separated separation sludge to the reduction step, and guiding the separated liquid to a biological treatment step. Weight reduction method. And 4) a sludge reduction tank having a means for introducing an oxygen-containing gas,
A solid-liquid separator for solid-liquid separation of the reduced sludge discharged from the sludge reduction tank is provided, and means for guiding a part of the solid-liquid separated separated sludge to the sludge reduction tank, and biological treatment of the separated liquid. An apparatus for reducing the amount of excess sludge by a microbiological method, which comprises means for guiding the apparatus. Is.

(Functions of the Invention) The excellent functions and effects of the present invention will be described below with reference to FIG. However, the embodiment of the present invention is not limited to this. In FIG. 1, the excess sludge 4 from the biological treatment tank 1 to be reduced is introduced into the excess sludge thickening tank 2, and the excess sludge concentration of 20,0
After being concentrated to about 00 to 30,000 mg / liter, it is transferred to the sludge reduction tank 3. On the other hand, it is advisable that the slime bacterium used for reducing the surplus of bacterial cells is subjected to increasing culture of one or more kinds of original strains from the natural world, and then used as seed bacteria for reducing sludge. In addition, it is also possible to select a strain having an excellent lytic action from among the strains distributed by the preservation organization and use it.

Myxobacteria 12 inoculated into the sludge reduction tank 3
May be a liquid mixed culture, or a so-called dry cell obtained by culturing myxobacteria in a liquid medium and / or a solid medium, separating and concentrating the cells by an ordinary means, and freeze-drying the cells. May be used. Furthermore, the combined use of both types of bacterial cells does not hinder the present invention. These inoculum cells 12 are inoculated and mixed into the sludge reduction tank 3 by any means such as a shower, a spray, an injector or simple piping.
Then, it is usually operated at around 25 ° C for 3 to 5 days under aerobic conditions to lyse excess sludge, rebuild assimilate into slime bacteria, and reduce sludge due to loss associated with respiration. .

The remaining sludge is the decomposition residue of activated sludge and the re-propagation of slime bacteria. These are led to a concentrating device 7, concentrated to an appropriate concentration, and if necessary, an organic and / or inorganic coagulant is injected, and then the remaining sludge is dehydrated by a dehydrator 8 which is usually used to form a dehydrated cake. obtain. As the concentrating device 7 and the dehydrator 8, any conventional device for biological treatment sludge can be used. Further, it is effective to mix the concentrated sludge 14 and / or the coagulated sludge 15 before dehydrating the residual sludge and then dehydrate it. Of course, the solid-liquid separation means may be other means.

In this separated liquid 10 (spill water), some of the mycelial bacteria and the bacterial cell contents in the excess sludge lysed by the mycobacterium are dissolved without being assimilated. Since the bacterial cell contents are mainly easily decomposable organic substances and, in turn, become BOD components, they are taken out of the system by the excess water pipe 9 and merged with the biological treatment apparatus 1 for human waste, sewage or organic waste water for treatment. Efficient and preferred. Alternatively, the BOD is introduced into the biological treatment step 11 which is separately and independently provided.
The components may be decomposed and then discharged to the outside. For these biological treatment steps 1 and 11, conventional biological treatment methods such as ordinary activated sludge treatment and carrier-introduced fluidized bed biofilm treatment can be appropriately applied. Further, the treatment of the separated liquid 10 by a method that does not depend on biological treatment is not hindered.

The myxobacteria slightly contained in the residual water are
It does not hinder the operation of activated sludge due to its slow growth rate compared to BOD assimilating bacteria in activated sludge, etc. It can be removed with. If applied to the membrane separation type activated sludge method, which has made remarkable progress in recent years, a particularly preferable system can be constructed.

On the other hand, since concentrated myxobacteria are present in the separated sludge, it can be used repeatedly if it is returned to the weight-reducing tank through the return pipe, and if it becomes stable as an inoculum, new inoculation of myxobacteria is not possible. It becomes unnecessary. However, in order to prepare for the initial enrichment culture and the reduction of myxobacteria due to some accident, it is preferable consideration to provide a culture facility for myxobacteria near the facility of the present invention or to prepare a transfer means from the outside. It does not prevent this.

(Function) The method for reducing excess sludge by the microorganism of the present invention is a microorganism, for example, Myxococcus (Myxo).
genus Coccus and Stigmatera
Lla), Cystobacter
r) genus, Melittangium
Myxobacteria including genus secrete lytic enzymes outside the microbial cells under aerobic conditions, lyse other viable microbial cells that exist around the mycelial bacterium, and use them as their own nutrient sources for growth. This is a completely new method of reducing excess sludge, focusing on the fact that The characteristic of the myxobacteria used in the present invention is that the specificity for predation is low,
The lytic enzyme produced outside the bacteria acts on and dissolves a wide range of microorganisms present in the sludge, so that the reduction of the sludge can be reliably achieved.

The bacteria in the other excess sludge cannot grow because the organic substances available to the outside are depleted. However, the myxobacteria used in the present invention have the above-mentioned effects, and thus the bacteria of other species can be grown under such conditions. Propagate as a source of organic matter. Further, since myxobacteria have a complicated life cycle, their energy efficiency is low, and the conversion rate of the food source used is low. Therefore, the yield is low when the organic matter is reconstructed as myxobacterial cells, and the effect of weight reduction is great. According to the present invention, the final excess sludge amount can be reduced to ½ amount or less, and the conventional troublesome sludge treatment is released.

[0018]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited thereto.

Example 1 The lytic action and function of each of the 6 types of strains of the tested myxobacteria shown in Table 2 below were confirmed. Excess activated sludge (sludge concentration of about 7,000 mg / liter) discharged from the nitrification and denitrification process of human waste was placed in a 0.5-liter round bottom flask, and expanded culture was performed with the two-membered culture medium of Table 1 The liquid culture of each myxobacteria shown in (3) was added and allowed to act at 3 cc / liter.
When shaking culture was carried out at a culture temperature of 25 ° C. and a culture time of 5 days,
Although a slight difference was observed depending on each strain, it was confirmed that the cell walls of the surplus activated sludge cells were almost completely dissolved and that the cell content liquid discharged to the liquid side was assimilated by myxobacteria. It was

[0020]

[Table 1]

* Escherichia coli Escherichia coli may be used as a viable bacterium added to the above-mentioned medium, or a prey may be obtained from the biological treatment step.

[0022]

[Table 2]

(Example 2) Excess activated sludge discharged from a nitrification solution circulation type nitrification and denitrification process was used as a target for weight reduction by slime bacteria. The general composition of this excess sludge is shown in Table 3.

[0024]

[Table 3]

On the other hand, as myxobacteria for lysing and reducing the excess sludge, there are Myxococcus xanthus Myxococ.
cus xanthus ATCC 25232 was selected. Using commercially available baker's yeast as a dietary bacterium of bacteria obtained from the microbial strain preservation organization (ATCC), the medium for two-membered culture shown in Table 1 was placed in a 1-liter round bottom flask.
Inoculate 0 cc, inoculate the fungus into 2 platinum loop culture solution,
The cells were cultivated at 5 ° C. for 5 days with shaking (aerobic growth culture).

Further, the sample (1) shown in Table 3 was selected as the test surplus activated sludge, and two 1 liter round bottom flasks (A,
500 cc each in B), 5 cc of the above-mentioned Myxococcus xanthus culture solution in A, and B as a control for 5 days at 25 ° C. (room temperature) with shaking culture, and after 5 days with shaking culture solution (A), ( Regarding B), the concentration of organic matter in the excess sludge and its reduction rate were obtained. The results are shown in Table 4.

[0027]

[Table 4]

As can be seen from Table 4, the reduction of the amount of excess activated sludge of night soil caused by the myxobacteria Myxococcus xanthus was extremely remarkable.

(Example 3) A surplus activated sludge obtained by treating the group groundwater substantially free from factory wastewater by the standard activated sludge method was selected, and two kinds of slime bacteria were inoculated to reduce the weight. First, add the activated sludge mixture from the aeration tank of the standard activated sludge facility.
0 liter was sampled and allowed to stand for 1.5 hours by the usual gravity precipitation method, and the activated sludge that had been precipitated and concentrated at the bottom was used as a test sample.
The analytical values of this sample are shown in Table 5.

[0030]

[Table 5]

This concentrated excess sludge was dispensed into two 1-liter round bottom flasks (A) and (B) in 500 cc aliquots,
(A) was inoculated with 2.5 cc each of the following two types (a) and (b) selected from the above-mentioned myxobacteria and 2.5 cc each of them was inoculated, and (B) was not added with the strain solution. a) Myxococcus xanthus
us xanthus ATCC25232) (b) Myxococcus fulbus
s fulvus ATCC23093) The medium, the culture conditions and the culture method used for the expansion culture of each myxobacteria are the same as in Example 2.

Further, the reduction of the concentration of the concentrated activated sludge by the myxobacteria was all carried out in accordance with Example 2. The execution results are shown in Table 6.

[0033]

[Table 6]

As shown in Table 6, the reduction of sludge was remarkable even in the reduction test of sewage system activated sludge using a mixed bacterial cell liquid of two kinds of myxobacteria Myxococcus xanthus and Myxococcus fulbus. Therefore, it was demonstrated that the present invention has a sufficient possibility of practical application.

[0035]

According to the present invention, as detailed above,
It is an invention from a completely different viewpoint from the prior art, and has the following operational effects. (1) To almost halve the amount of excess sludge that is extremely difficult to treat discharged from human waste treatment, sewage treatment or biological treatment of organic wastewater, especially biological oxidation treatment. You can (2) In addition, by adopting the present invention, the sludge treatment facility can be reduced in size and the treatment cost can be remarkably reduced.

(3) Of the various sludges discharged from the biological treatment process, the generation amount of surplus sludge, which is the most difficult to treat, is halved, so sludge treatment as a total process, particularly dehydration, becomes extremely easy. (4) It is possible to significantly reduce the amount of myxobacteria to be inoculated by circulating and returning a part of the separated sludge from the concentration step and dehydration step to the sludge reduction tank. Inoculation of bacteria can be omitted.

[Brief description of drawings]

FIG. 1 is a block diagram showing an example of a method and apparatus of the present invention.

[Explanation of symbols]

 1 Biological Treatment Tank 2 Excess Sludge Concentration Tank 3 Sludge Reduction Tank 4 Excess Sludge 5 Sludge Return Pipe 7 Concentrator 8 Dehydrator 9 Excess Moisture Pipe 10 Separation Water 11 Biotreatment Process 12 Mucus Bacteria 13 Air 14 Concentration Initial Sludge 15 Concentration Coagulated sludge 16 Surplus water pipe 17 Separation water

Claims (4)

[Claims] 1. A surplus sludge microorganism characterized in that surplus sludge discharged from a biological treatment process of wastewater is inoculated with a single strain or multiple strains of myxobacteria having a bacteriolytic action and allowed to act under aerobic conditions. Weight reduction method. 2. A weight-reducing step in which surplus sludge discharged from the biological treatment step of wastewater is inoculated with a single strain or a plurality of strains of myxobacteria having a bacteriolytic action and allowed to act under aerobic conditions.
Microbiology of excess sludge characterized by having a step of solid-liquid separation of the reduced sludge discharged from the weight reduction step, and recycling a part of the solid-liquid separated separation sludge to the weight reduction step Weight reduction method. 3. A weight-reducing step in which surplus sludge discharged from the biological treatment step of wastewater is inoculated with a single strain or multiple strains of myxobacteria having a bacteriolytic action and allowed to act under aerobic conditions.
In addition to having a step of solid-liquid separation of the reduced sludge discharged from the weight reduction step, a part of the solid-liquid separated separation sludge is circulated back to the weight reduction step to guide the separated liquid to the biological treatment step. A method for reducing the amount of excess sludge by a microbe. 4. A separation sludge that is solid-liquid separated, including a sludge reduction tank having a means for introducing an oxygen-containing gas, and a solid-liquid separation device for solid-liquid separation of the reduction sludge discharged from the sludge reduction tank. And a means for guiding a part of the sludge to the sludge reduction tank, and a means for guiding the separated liquid to the biological treatment apparatus.