JP5425680B2 - Wastewater treatment method using microorganisms - Google Patents

Description

  The present invention relates to a wastewater treatment method using two or more kinds of microorganisms belonging to the genus Bacillus and a microorganism belonging to the genus Bacillus having the ability to reduce BOD used in such wastewater treatment methods.

Wastewater from factories or business establishments causes water pollution due to discharge into rivers and oceans. Therefore, BOD (Biochemical Oxygen Demand) is one of the indicators for evaluating the water quality in wastewater. It is regulated by the wastewater standard used as an indicator. For example, the daily mean discharge water is 50 m ³ or more factory or workplace wastewater, BOD is effluent standards for acceptable limit 160 mg / L, the days mean 120 mg / L and the limit is determined. Therefore, in general factories or business establishments, in order to prevent wastewater exceeding the standard, wastewater treatment is performed in a septic tank attached to the facility and installed individually to reduce the BOD of the wastewater and discharge it.

  In general, wastewater is treated by the activated sludge treatment method in the septic tank, and microorganisms are responsible for one step of the decomposition treatment. The decomposition treatment by microorganisms changes the water temperature due to the climate, the nature of the wastewater, or the dissolved oxygen in the wastewater. There is a problem that the processing efficiency varies depending on the amount. For this reason, in a large septic tank, an adjustment tank or the like is provided in the preceding stage, and measures are taken to prevent a decrease in processing efficiency, such as adjusting the change in water quality of the microorganism treatment tank as uniformly as possible. On the other hand, in small septic tanks where it is difficult to provide an adjustment tank, it is difficult to prevent changes in the water quality of the treatment tank, and in particular, it is susceptible to seasonal changes in water temperature due to the small septic tank volume. There is. For this reason, if the water temperature of the treatment tank decreases in winter, the wastewater treatment capacity by microorganisms declines, making it difficult to keep the BOD of wastewater within the wastewater standard.

  In order to solve such problems and to efficiently perform wastewater treatment even at low temperatures, conventionally, measures such as providing temperature control in the septic tank or embedding in the ground have been taken. In addition, a sewage septic tank (see Patent Document 1) in which heating means is provided in the aeration tube and heated air is supplied into the contact aeration tank to raise the sewage temperature, and drainage is performed by sulfuric acid respiration of anaerobic microorganisms. The organic matter is decomposed, the wastewater from the anaerobic treatment tank is decomposed by aerobic microorganisms in the aerobic treatment tank, and the hydrogen sulfide and sulfide in the wastewater are oxidized to obtain sulfate ions. There is known a wastewater treatment method using an upward flow anaerobic sludge bed type anaerobic treatment tank that returns treated water to the wastewater inflow side of the anaerobic treatment tank (see Patent Document 2). However, improvement of equipment such as septic tanks or wastewater treatment equipment has a problem in terms of cost due to new equipment introduction costs and maintenance costs.

  On the other hand, it is also known to use Bacillus bacteria for wastewater treatment. For example, “yu”, which is discharged in the process of manufacturing tofu, frozen tofu, fried dough, etc. A processing method of “yu” characterized by decomposition by microorganisms mainly composed of Bacillus bacteria as a main component (see Patent Document 3), and reticulated rotation to which a microorganism film made predominantly of Bacillus species mixed bacteria is attached A method of performing biological treatment by introducing sewage containing an organic substance and nutrients into a reticulated rotary bacillus contact tank equipped with a bacillus contact body has been proposed (see Patent Document 4).

Japanese Patent Laid-Open No. 10-192875 JP 2004-148242 A JP 2008-178841 PR JP 2008-253948 A

  An object of the present invention is to provide a low-cost and simple wastewater treatment method for efficiently treating wastewater having a high BOD value without being affected by changes in water temperature, and a BOD belonging to the genus Bacillus that can be used in the wastewater treatment method. The object is to provide a microorganism having a reducing ability.

  In order to solve the above-mentioned problems, the present inventor isolated microorganisms from soil, septic tank or the like. From a total of 893 microorganisms, 658 strains isolated from soil samples and 235 strains isolated from wastewater samples in septic tanks, etc., they grow well over a wide temperature range and efficiently produce organic matter at low temperatures. We have discovered microorganisms belonging to the genus Bacillus that can be decomposed and greatly reduce the BOD of low temperature waste water. Furthermore, by combining and using two isolated microbial strains belonging to the genus Bacillus, it has been found that wastewater treatment can be performed stably and efficiently even if the water temperature of the wastewater fluctuates, and the present invention is completed. It came.

That is, the present invention provides (1) biochemical oxygen demand in wastewater by adding and culturing a mixture of two or more microorganisms belonging to B. thuringiensis having BOD reducing ability to the wastewater ( A wastewater treatment method for reducing BOD), wherein a microorganism belonging to the Bacillus thuringiensis has a culture solution of the microorganism in a tryptic soy medium in an amount of 0.1 v relative to a model wastewater [1] having the following composition: / v% was added, and the BOD reduction of 50% or more in the model waste water after 48 hours at 25 ° C., and a viable der Ru microorganism at 10 to 15 ° C. in tryptic soy medium (pH 7), wherein mixtures of two or more of a microorganism belonging to Bacillus thuringiensis, the equal mixture of the individual culture in tryptic soy medium of the microorganism, versus the model waste water [2] Was added 0.1 v / v% combined Te is a mixture of two or more microbial BOD reduction rate is 50% or more in the model waste water after 48 hours at 15 ° C.,
The present invention relates to a wastewater treatment method.
(1) Model wastewater [1] Composition
・ Soluble starch; 0.092 g / L
・ Peptone; 0.196 g / L
・ Yeast extract; 0.196 g / L
・ Meat extract; 0.224 g / L
・ Sodium chloride; 0.020 g / L
・ Magnesium sulfate heptahydrate; 0.012 g / L
・ Potassium dihydrogen phosphate; 0.056 g / L
・ Potassium chloride; 0.040 g / L
・ Ammonium chloride; 0.060 g / L
BOD: 600mg / L
(2) Model wastewater [2] Composition: Glucose; 0.60 g / L
・ Collagen peptide; 1.20 g / L
・ Yeast extract; 0.60 g / L
・ Pork bouillon; 0.60 g / L
・ Sodium chloride; 0.10 g / L
・ Magnesium sulfate heptahydrate; 0.28 g / L
・ Potassium dihydrogen phosphate; 0.20 g / L
・ Potassium chloride; 0.06 g / L
・ Ammonium chloride; 0.30 g / L
BOD: 2000mg / L

The present invention is also characterized in that (2) a mixture of two or more microorganisms belonging to Bacillus thuringiensis having the ability to reduce BOD is added to and cultured in wastewater in a septic tank without temperature control equipment (1 ) The waste water treatment method described in ( 3 ), or ( 3 ) Bacillus thuringiensis is Bacillus thuringiensis HS-25 (FERM P- 21940) or Bacillus thuringiensis HS-41 (FERM P- 21194). It is related with the processing method of the waste_water | drain as described in said ( 2 ).

Furthermore, the present invention provides ( 4) Bacillus thuringiensis having a B OD lowering ability, wherein the culture solution of the Bacillus thuringiensis in tryptosoy medium is 0.1 v / v relative to the model waste water [1]. % was added, and the BOD reduction of 50% or more in the model waste water after 48 hours at 25 ° C., and Bacillus thuringiensis, characterized in that in tryptic soy medium (pH 7) is capable of growing at 10 to 15 ° C. Or ( 5 ) Bacillus thuringiensis HS-25 (FERM P- 21940) or Bacillus thuringiensis HS-41 (FERM P- 21194), which relates to Bacillus thuringiensis according to ( 4 ) above .

  According to the method of the present invention, it is possible to stably and efficiently treat low-temperature wastewater or wastewater whose water temperature fluctuates without introducing large-scale equipment or improving the apparatus, and lower BOD.

It is a figure which shows the result of the waste water treatment test which added HS-25 stock | strain and HS-41 stock each independently. It is a figure which shows the result of the waste water treatment test which mixed and added HS-25 stock | strain and HS-41 stock | strain.

  As a Bacillus microorganism of the present invention, 0.1 part by volume of the culture solution of the microorganism in tryptosoy medium is added to 100 parts by volume of the model waste water [1] having a BOD of 600 mg / L, and the mixture is 48 at 25 ° C. There is no particular limitation as long as the microorganism has a BOD reduction rate in a model drainage after time culture of 50% or more and has a BOD reduction ability belonging to the genus Bacillus that can grow at 10 to 15 ° C. in a tryptic soy medium (pH 7). In addition, as a method for treating waste water of the present invention, an equal volume mixture of individual culture solutions in tryptosoy medium is used in an amount of 0.1 parts by volume with respect to 100 parts by volume of the model waste water [2] having a BOD of 2000 mg / L. And a mixture of two or more of the aforementioned Bacillus microorganisms of the present invention, which has a BOD reduction rate of 50% or more in the model waste water after 48 hours of incubation at 15 ° C., is added to the waste water. -If it is the method of culture | cultivating and reducing BOD in waste_water | drain, it will not restrict | limit in particular, Here, the culture solution in the said tryptic soy culture medium is 30 by tryptic soy culture medium ("tryptosome broth" by Nissui Pharmaceutical Co., Ltd.) This refers to a suspension of each bacterium obtained by culturing at 24 ° C. for 24 hours and adjusting the culture solution to an absorbance value of 0.2 (wavelength 660 nm).

  The Bacillus microorganism of the present invention is preferably a Bacillus microorganism capable of growing in a wide temperature range from 10 to 40 ° C., preferably 10 to 50 ° C., from a low temperature region to a high temperature region. Bacillus microorganisms that can grow in a wide temperature range can be suitably used for wastewater treatment in an indoor or outdoor septic tank without temperature control equipment, for example, in a septic tank having a capacity of 500 to 3000 L. The microorganism of the genus Bacillus of the present invention is a mixture of a preculture in a tryptic soy medium or the like, preferably an equivalent mixture, and is 0.05 to 0.5 parts by volume, preferably 0.1 to 0. Two parts by volume are preferably added periodically.

Examples of Bacillus microorganisms of the present invention include Bacillus microorganisms such as Bacillus thuringiensis, Bacillus subtilis, B. licheniformis, and more specifically Bacillus thuringiensis HS-25 ( Suitable examples include microorganisms belonging to Bacillus thuringiensis, such as FERM P- 21940) and Bacillus thuringiensis HS-41 (FERM P- 211941).

  Further, when the wastewater to be treated by the wastewater treatment method of the present invention contains a large amount of fats and oils, in addition to the Bacillus microorganisms of the present invention, it belongs to microorganisms having oil-fat decomposability, for example, the genus Burkholderia. Microorganisms having oil-and-fat degradability, especially B. multivorans SB-B strain (Accession No. FERM P-21784) and B. multivorans SB-H strain (Trust) No. FERM P-21783) and known microorganisms commonly used for wastewater treatment such as Bacillus sp., Pseudomonas sp., Micrococcus sp. You can also.

  In the wastewater treatment of the present invention, a carbon source, a nitrogen source, and the like can be blended as necessary, but it is preferable not to blend. During continuous decomposition, air is exhausted through the exhaust port at the same time as air is fed into the processing tank by a diffuser tube or by rotating a stirring plate installed in the processing tank continuously or intermittently. It is preferable. The decomposition treatment temperature and pH do not usually need to be controlled, but can be controlled to 20 to 40 ° C. and pH 6 to 8 as necessary.

  EXAMPLES Hereinafter, although an Example demonstrates this invention more concretely, the technical scope of this invention is not limited to these illustrations.

1. Screening of strains In order to obtain microorganisms that grow in a wide range of environments and are capable of stable wastewater treatment, strains were screened by the direct separation method. Samples were collected from 37 places such as soil in various places in Japan and wastewater in septic tanks of food factories, suspended in sterilized distilled water and diluted 10-fold, and then standard agar medium (meat extract 5.0 g / L, peptone 10 0.0 g / L, sodium chloride 5.0 g / L, Kanten 15.0 g / L, pH 7.0: Nissui Pharmaceutical Co., Ltd.) and cultured at 30 ° C. for 48 hours. After the culture, 893 strains of microorganisms were isolated from the emerged colonies, 658 strains for soil samples and 235 strains for drainage samples such as waste water in the septic tank.

2. Organic matter resolution test on solid medium The resulting 893 strains of microorganisms were evaluated for protein or fat resolution. A solid medium for resolution evaluation was prepared by the following method using pork protein, milk protein (casein) and gelatin for proteins and animal fat (lard) for fats as substrates.

(1) Production method of agar medium using pork protein as substrate Substrate minced pork loin is immersed in an equal amount of sterile physiological saline overnight, and then centrifuged at 6000 rpm for 20 minutes. Heat-sterilized for a minute to obtain a pork protein suspension. Add 10.0 g of agar to 1 L of 0.1 M phosphate buffer (pH 6.8), dissolve by heating, sterilize at 120 ° C. for 15 minutes, add 10 g of the pork protein suspension and stir well, then sterilize It was dispensed into a petri dish and solidified.

(2) Preparation method of agar medium using milk protein as substrate Substrate 1L of 0.4% sodium citrate solution 2.5g yeast extract, 5.0g tryptone, 1.0g glucose, 15.0g agar, 1M calcium chloride solution 20 0.0 ml and 10.0 g of sodium caseinate (Wako Pure Chemical Industries, Ltd.) were added and dissolved by heating, sterilized at 120 ° C. for 15 minutes, then dispensed into a sterilized petri dish and solidified.

(3) Preparation method of medium using gelatin as substrate Add 1.0 g of meat extract, 10.0 g of polypeptone, 1.0 g of yeast extract, and 200 g of gelatin (Wako Pure Chemical Industries, Ltd.) to 1.0 L of sterile distilled water. After hot dissolution and dispensing 5 mL each into a small test tube, sterilization was performed at 120 ° C. for 15 minutes to solidify.

(4) Preparation method of agar medium using animal fat / oil as a substrate Standard agar medium (meat extract 5.0 g / L, peptone 10.0 g / L, sodium chloride 5.0 g / L, agar 15.0 g / L, pH 7) 0.0: made by Nissui Pharmaceutical Co., Ltd.) 1 L of pure lard (Primaham Co., Ltd.) was added and dissolved by heating, sterilized at 120 ° C. for 15 minutes, then dispensed into a sterile petri dish and solidified. It was.

(5) Evaluation of resolution With respect to an agar medium using pork protein, milk protein, and animal fat as a substrate, a well having a diameter of 5 mm is aseptically opened on the prepared plate agar medium, and an absorbance value of 0.2 is placed in the well. 30 μL of the suspension of the isolated strain adjusted to (wavelength 660 nm) was injected and cultured at 32 ° C. for 5 days. The evaluation of the resolution is based on the size of the clear zone formed by decomposing each substrate after culturing, with “−” indicating that the clear zone was not formed, “+” indicating that the diameter is less than 10 mm, and diameter. The evaluation was made in four grades, “++” for 10 mm or more and less than 20 mm, and “++++” for diameters of 20 mm or more. For the high-layer medium using gelatin as a substrate, colonies of the isolated strain were collected with a platinum wire, punctured into the high layer of the medium, and cultured at 32 ° C. for 5 days. For the evaluation of resolution, tilt the small test tube after culturing, and from the appearance evaluation of the liquefied state of the culture medium, “−” indicates that it was not liquefied, “+” indicates that the trace amount was liquefied, and “++” indicates that it was slightly liquefied. The completely liquefied product was evaluated in four grades, “++++”. The evaluation results of the resolution for each substrate are shown in Table 1.

  A total of 15 strains (12 isolates from soil) that are evaluated as “++++” for the degradation degree of 3 or more of 4 types of substrates of pork protein, milk protein (casein), gelatin, and animal fat (lard) (Strain Nos. S-7, No. S-25, No. S-41, No. S-162, No. S-163, No. S-180, No. S-184, No. S-202, No. S-361, No. S-427, No. S-496, No. S-511), 3 strains separated from wastewater (No. J-52, No. J-61, No. J-216) )was gotten. As a result of simple determination of microbial classification based on morphological and physiological properties of 15 isolates, 12 strains of 15 strains belonged to the genus Bacillus, 2 strains belonged to the genus Enterobacteriaceae, and 1 strain consisted of Flavobacterium. (Flavobacterium) (Table 2).

(3) BOD reduction test by model waste water The drainage treatment ability of the 15 microorganisms obtained was evaluated based on the BOD reduction rate of the model waste water. Each of the 15 isolates was treated with tryptic soy medium (peptone 17.0 g / L, soybean peptone 3.0 g / L, sodium chloride 5.0 g / L, glucose 2.5 g / L, potassium monohydrogen phosphate 2.5 g / L: 400 μL of each bacterial suspension obtained by culturing for 24 hours at 30 ° C. with “Tryptosome Bouillon” manufactured by Nissui Pharmaceutical Co., Ltd. and adjusting the culture solution to an absorbance value of 0.2 (wavelength 660 nm) Was added to 400 mL of model wastewater [1] (BOD: 600 mg / L), and cultured with shaking at 25 ° C. for 48 hours.

<Model wastewater [1] composition> (g / L)
・ Soluble starch * 1 0.092
・ Bact Pepton * 1 0.196
・ Yeast Extract * 1 0.196
・ Meat extract (Beef Extract) * 1 0.224
・ Sodium chloride * 2 0.020
・ Magnesium sulfate heptahydrate * 2 0.012
・ Potassium dihydrogen phosphate * 2 0.056
・ Potassium chloride * 2 0.040
・ Ammonium chloride * 2 0.060
* 1 BD Difco * 2 Wako Pure Chemical Industries, Ltd.

  After 48 hours of culturing in the model wastewater, the number of bacteria in the culture solution is measured, and the BOD of each model wastewater is measured according to a standard method (JIS K 0102 21 and 32) to the initial BOD (240 mg / L) of the wastewater. BOD reduction rate was calculated. The results are shown in Table 2. Since the BOD of the wastewater was reduced by 22.5% to 59.4% depending on the added isolate, as a microbial strain with particularly high wastewater treatment capacity, the strain that reduced the BOD concentration in the model wastewater by 45.0% or more, No. . J-52, no. J-61, no. S-25, No. S-41, No. S-163, no. Six strains of S-180 were selected.

(4) Growth characteristic test About 6 selected strains, the growth characteristic with respect to pH and temperature was evaluated. 100 mL of a suspension of the isolated strain adjusted to an absorbance value of 0.2 (wavelength 660 nm) was added to 10 mL of tryptosoy medium (Nippon Seiyaku Co., Ltd. "Tryptosoya bouillon") adjusted to pH 7, 7, and 9, respectively. After addition, shaking culture was performed at 10 ° C., 15 ° C., 40 ° C., and 50 ° C. for 4 days, respectively. Evaluation of the growth characteristics is based on the degree of growth of each strain after culturing using the absorbance value at a wavelength of 660 nm as an index, 0.0 being no growth, “−”, 0.1 to less than 0.2 being growth “+”, 0. Two or more were evaluated in three stages of growth “++”. The results are shown in Table 3.

  Strain No. 1 which was observed to grow at 10 ° C. S-25 and No. Two strains of S-41 were selected. No. The S-25 strain grows under conditions of pH 7 to 10-15 ° C and pH 5 to 40-50 ° C. The S-41 strain was a strain that grew at 10 to 40 ° C. at pH 7. Therefore, no. S-25 and No. S-41 was a strain that grew even at 10 ° C. in tryptic soy medium (pH 7), and treated model drainage [1] (BOD: 600 mg / L) at 25 ° C. for 48 hours to reduce BOD by 50%.

(5) Identification of strains S-25 and No. In order to classify the two strains of S-41 more accurately, identification based on morphological and physiological properties and identification based on genetic properties were performed. Identification based on morphological and physiological properties confirmed Gram stainability, shape, spore-forming ability, catalase oxidase activity, and glucose degradability. In identification based on genetic properties, No. S-25 and No. Genomic DNA was extracted from the S-41 strain, and genetic analysis based on the base sequence of 16S rRNA gene was performed according to a conventional method. The analyzed isolate No. The 16S rRNA gene sequence of S-25 is represented by SEQ ID NO: 1, and the isolated strain no. The 16S rRNA gene sequence of S-41 is shown in SEQ ID NO: 2, respectively. As a result of the homology search, no. S-25 and No. Since S-41 showed the highest homology of 99.2% and 99.8% with respect to Bacillus thuringiensis ATCC 10792 strain, both isolated microorganisms were Bacillus thuringien. It was identified as a bacterial species close to cis (B. thuringiensis). The results of identification are shown in Table 4.

From the identification results of the above bacterial species, No. The S-25 strain is a B. thuringiensis HS-25 strain, no. S-41 strain was named B. thuringiensis HS-41 strain. HS-25 strain, independently in 2010, March 16, with National Institute of Advanced Industrial Science and Technology, International Patent Organism Depositary consignment number to (Japan Higashi, Tsukuba, Ibaraki chome address 1 Central 6) FERM P -21940 deposited as, the HS-41 strain, 2010 March 16, with an independent National Institute of Advanced industrial Science and technology, International Patent organism Depositary consignment number to the (sixth center Higashi, Tsukuba, Ibaraki address chome 1, Japan) Deposited as FERM P- 211941.

The safety of the selected HS-25 strain and HS-41 strain was confirmed by an acute oral toxicity test using mice. Five 5-week-old ICR mice (manufactured by Japan SLC Co., Ltd.) were bred in an environment of 23 ° C. ± 2 ° C. and an illumination time of 12 hours / day, and the strains HS-25 and HS-41 were used. A suspension (10 ⁸ CFU / mL) 20 mL / kg was orally administered once daily. Mouse specimens were observed for 14 days, and autopsy was performed after the observation period. No abnormalities were observed in the mice administered with the suspensions of the HS-25 and HS-41 strains, and the LD50 value was 20 mL / kg or more, and there was no problem with safety.

(6) BOD reduction test of model wastewater by wastewater treatment experimental device To confirm the practicality of HS-25 and HS-41 strains in wastewater treatment, 700L wastewater treatment experimental device as a system close to the actual wastewater treatment process Was used to measure the BOD reduction rate due to wastewater treatment of two strains.

(6-1) A wastewater treatment test was performed using each of the HS-25 and HS-41 strains alone as a test strain to which strains were added alone. HS-25 strain or HS-41 strain was cultured for 24 hours at 30 ° C. in Tryptosoy medium (Nissui Pharmaceutical Co., Ltd. “Tryptosoya bouillon”), and the culture solution was adjusted to an absorbance value of 0.2 (wavelength 660 nm). 700 mL of the resulting bacterial suspension was added to 700 L of model wastewater [2] (BOD: 2000 mg / L) having the following composition, followed by culture treatment by aeration using an air diffuser at 15 ° C. for 48 hours. went.

<Model wastewater [2] composition> (g / L)
・ Glucose (Glufinal) * 3 0.60
・ Collagen peptide (CPB-5) * 4 1.20
・ Yeast extract (super yeast extract) * 5 0.60
・ Pork bouillon (A-6521) * 6 0.60
・ Sodium chloride * 2 0.10
・ Magnesium sulfate heptahydrate * 2 0.28
・ Potassium dihydrogen phosphate * 2 0.20
・ Potassium chloride * 2 0.06
・ Ammonium chloride * 2 0.30
* 2 Wako Pure Chemical Industries, Ltd. * 3 Sanei Saccharification Co., Ltd. * 4 Zerice Co., Ltd. * 5 Ajinomoto Co., Ltd. * 6 Nikken Foods Co., Ltd.

  The BOD of the model wastewater collected at each time point of the culture treatment was measured according to a standard method (JIS K 0102 21 and 32), and the BOD reduction rate relative to the initial BOD (2000 mg / L) of the wastewater was calculated. The results are shown in FIG. It was confirmed that the treatment for 48 hours at 15 ° C. decreased the BOD by 53% for the HS-25 strain and 51% for the HS-41 strain, respectively.

(6-2) Addition of strains A wastewater treatment test was performed in which HS-25 and HS-41 strains were mixed and added as test strains. The HY-25 and HY-41 strains were each cultured for 24 hours at 30 ° C. in Tryptosoy medium (“Tryptosoya bouillon” manufactured by Nissui Pharmaceutical Co., Ltd.), and the culture solution was adjusted to an absorbance value of 0.2 (wavelength 660 nm). An equal amount of the suspension of each bacterium thus obtained was mixed, and 700 mL of the mixed microbial solution was added to 700 L of model waste water [2] (BOD: 2000 mg / L) having the above composition, and 48 at 15 ° C. The culture treatment was carried out by aeration using a diffuser for a time. In addition, as a comparative control, a culture treatment was performed under the same conditions using a commercial bacterium for septic tank as a test strain.

  The BOD of the model wastewater collected at each time point of the culture treatment was measured according to a standard method (JIS K 0102 21 and 32), and the BOD reduction rate relative to the initial BOD (2000 mg / L) of the wastewater was calculated. The results are shown in FIG. It was confirmed that the wastewater treatment at a low temperature (15 ° C.) can be effectively performed by adding the HS-25 strain and the HS-41 strain in comparison with the case of using a commercially available conventional bacterium.

Claims (5)

A wastewater treatment method for reducing the biochemical oxygen demand (BOD) in wastewater by adding and culturing a mixture of two or more microorganisms belonging to Bacillus thuringiensis having BOD lowering ability to wastewater There,
The microorganism belonging to the Bacillus thuringiensis added a culture solution of the microorganism in a tryptic soy medium to a model wastewater [1] having the following composition at 0.1 v / v% and cultured at 25 ° C. for 48 hours. of BOD reduction rate in the model waste water is at least 50%, and a viable der Ru microorganism at 10 to 15 ° C. in tryptic soy medium (pH 7),
A mixture of two or more types of microorganisms belonging to the Bacillus thuringiensis is added to the model wastewater [2] by adding 0.1 v / v% of an equal amount of each culture solution in the tryptic soy medium of the microorganisms. and a mixture of two or more microbial BOD reduction rate is 50% or more in the model waste water after 48 hours at 15 ° C.,
A method for treating wastewater.
(1) Model wastewater [1] Composition
・ Soluble starch; 0.092 g / L
・ Peptone; 0.196 g / L
・ Yeast extract; 0.196 g / L
・ Meat extract; 0.224 g / L
・ Sodium chloride; 0.020 g / L
・ Magnesium sulfate heptahydrate; 0.012 g / L
・ Potassium dihydrogen phosphate; 0.056 g / L
・ Potassium chloride; 0.040 g / L
・ Ammonium chloride; 0.060 g / L
BOD: 600mg / L
(2) Model wastewater [2] Composition: Glucose; 0.60 g / L
・ Collagen peptide; 1.20 g / L
・ Yeast extract; 0.60 g / L
・ Pork bouillon; 0.60 g / L
・ Sodium chloride; 0.10 g / L
・ Magnesium sulfate heptahydrate; 0.28 g / L
・ Potassium dihydrogen phosphate; 0.20 g / L
・ Potassium chloride; 0.06 g / L
・ Ammonium chloride; 0.30 g / L
BOD: 2000mg / L The wastewater treatment method according to claim 1, wherein a mixture of two or more microorganisms belonging to Bacillus thuringiensis having BOD reducing ability is added and cultured to wastewater in a septic tank without temperature control equipment. The method for treating wastewater according to claim 2 , wherein the Bacillus thuringiensis is Bacillus thuringiensis HS-25 (FERM P- 21940) or Bacillus thuringiensis HS-41 (FERM P- 21194). . B. thuringiensis having the ability to reduce B OD, and adding 0.1 v / v% of the culture solution of the Bacillus thuringiensis in tryptosoy medium to a model wastewater [1] having the following composition: Bacillus thuringiensis characterized by having a BOD reduction rate of 50% or more in model waste water after 48 hours of culturing at 25 ° C., and capable of growing at 10-15 ° C. in tryptic soy medium (pH 7).
(1) Model wastewater [1] Composition
・ Soluble starch; 0.092 g / L
・ Peptone; 0.196 g / L
・ Yeast extract; 0.196 g / L
・ Meat extract; 0.224 g / L
・ Sodium chloride; 0.020 g / L
・ Magnesium sulfate heptahydrate; 0.012 g / L
・ Potassium dihydrogen phosphate; 0.056 g / L
・ Potassium chloride; 0.040 g / L
・ Ammonium chloride; 0.060 g / L
BOD: 600mg / L Bacillus thuringiensis HS-25 (FERM P -21940) or Bacillus thuringiensis according to claim 4, characterized in that the Bacillus thuringiensis HS-41 (FERM P -21941) .

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