JP2003024979A - Algae treatment method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To construct a high performance economical system capable of killing or decomposing water bloom using algae dissolving bacterial cells collected from the natural environment generating water bloom and succeedingly detoxifying microcystin discharged from water bloom by enzyme secreted by bacterial cells isolated from the same environment to be cultured and capable of being stably operated over a long period of time, and to realize a water treatment process capable of putting a BOD component generated accompanied by the decomposition of water bloom to practical use not only to reduce the consumption of enzyme producing bacteria in a rear stage but also to reduce the BOD component. SOLUTION: In the algae treatment method, an algae-containing liquid is brought into contact with algae dissolving microorganisms belonging to the genus Brevibacillus to kill and decompose algae and microcystine discharged by the decomposition of algae is subsequently brought into contact with Sphingomonus bacteria to be detoxified.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to lakes, ponds, dams,
The present invention relates to a treatment method for algae-killing and detoxifying floating cyanobacteria (blue-green algae) that occur in closed water areas such as moats and inland seas.

[0002]

2. Description of the Related Art When the temperature of water is relatively high, a large amount of blue-green algae (cyanobacteria), called blue-green algae, are generated in closed water areas such as eutrophic lakes and dams, and destroy the natural environment of the water areas. In many cases, the use of domestic water and industrial water is significantly hindered. In addition, the water-bloom struck on the shore of the lake etc. rots and gives off a foul odor,
It is collected by a method such as suction filtration and disposed of such as drying and incineration, but it is currently ineffective.

By the way, blue-green alga is a common name for cyanobacteria including many species, and includes cyanobacteria of the genus Microsystemus, genus Anabaena, genus Osylatoria, and the like. The genus Microcystis is a unicellular sphere-shaped bacterium and is frequently detected in Japan. This bacterium is also known as a microcystin-producing bacterium, which is attracting attention as a liver toxin and a carcinogen promoting substance. Not all cyanobacteria have the same toxicity, but there are many that act as neurotoxins and non-toxic ones, and also have different sensitivities to chemicals. Microcystin is a cyclic peptide having a molecular weight of about 1,000, and about 50 kinds of microstructures having different structures have been reported so far. The occurrence of water-bloom is a result of eutrophication of lakes, that is, it reflects environmental pollution and is closely related to the lives of local residents. It is necessary to select an appropriate treatment method according to the above. What is more important is a system that can collect and dispose of processing equipment and fungi that have been brought in so as not to disturb the ecosystem of the place.
The decision must be made after confirming that no new environmental pollution will occur with the disposal.

As a conventional method for treating water-bloom, it is killed by an algicidal agent such as copper sulfate, chlorine, ozone and β-cyano-L-alanine (JP-A-11-71203 and JP-A-11-70395). Disclosed in Japanese Patent Laid-Open No. 11-477, which inactivates the cell proliferation effect by cavitation effect caused by ultraviolet irradiation or high-speed flow (Japanese Patent Laid-Open No. 11-477)
No. 85), aquatic earthworms, Daphnia magna, Monas gutura and other organisms for predation (Japanese Patent Application Laid-Open Nos. 7-100489, 8-126, and 8-117790). (Described in) is proposed. Further, in Japanese Patent No. 3050578, Bacillus, Saccharomyces genus or dactylosporandium spp strains of microorganisms are sprayed on water-blooming water near the surface of the water, and the buoyancy of the water-bloom is lost to precipitate on the pond floor or Techniques for algicidal methods and agents are shown. Further, a technique utilizing mutant bacteria (Japanese Patent Laid-Open No. 62-499).
(Described in Japanese Patent Publication No. 99) is also proposed. Reim et al. Bacillus brevis (B
It has been pointed out that the culture solution of acillus brevis) is algae-soluble, which is the lysis of cell membranes by a substance such as Gramicidin. (Can.J.Microbiol., 20,981-98
6,1974 Reim, RL, MSShane, & RECannon)

Since various drawbacks have been pointed out in some of the above-mentioned various treatment methods and some of them are still in the research stage, practical techniques for large-scale water bodies have not been completed yet. The issues for practical use are that there is no secondary pollution of the environment due to the materials used, a system that reliably detoxifies the toxic component microcystin that elutes with the disposal of water-bloom, and a treatment system. Are economical, easy to handle, and can be recovered as needed without disturbing the ecological system of the environment.

[0006] It has been reported that there are more than 50 homologues and derivatives of microcystin produced by the microalgae of Microcystis, and 7 types of homologues such as microcystin RR, LR and YR are derived from Japanese cyanobacteria. The body is confirmed. Furthermore, according to the investigation by the present inventor, the half-life of microcystin LR released from the cells of cyanobacteria in domestic lakes is about 10 weeks, and it exists fairly stably in water.
It should be noted that when chlorine treatment is performed, several compounds called dihydrooxymicrocystin, including compounds in which two hydroxyl groups are added to the double bond at the 4,5-position of the conjugated diene of Adda, Although it was generated and could be made harmless, there is concern about the environmental impact of chlorination. (Studies on biosynthesis of Microcystin produced by toxic cyanobacteria (I) Bulletin No. 4 of Meijo University Research Institute, pp127-140 (1999.3) Harada, Fujii, K.SIVONEN) Australian Jones et al. It has been reported that Sphingomonas spp. Hydrolyzes microcystin into a linear compound. (Enzymatic pathway for the bacterial degradati
on of the cyanobacterial cyclic peptide toxin micro
cystin LR.Appl.Environ Microbiol, 62 (11), 4086-409
4,1996, Bourne DG, Jones GJ, Blakeley RL, Jones A,
Negri AP, Riddles P.) However, the influence on the environment due to the hydrolysis treatment and the problems in practical application have not been clarified.

[0007]

The problem to be solved by the present invention is to kill a water-bloom by using a lysing fungus body collected from the natural environment in which the water-bloom is generated, and then secrete the fungus body isolated and cultured from the same environment. The purpose is to construct a high-performance, economically stable system capable of degrading microcystin released from water-bloom by the enzyme that is used, capable of stable operation for a long period of time. Another issue is B that occurs with the decomposition of blue-green algae.
It is to utilize the OD component to realize a water treatment process that reduces the consumption of the enzyme-producing bacteria in the latter stage and reduces the BOD component.

[0008]

Means for Solving the Problems According to the present invention, a liquid containing algae is brought into contact with a brevibacillus-type lytic microorganism to kill or decompose algae, and then microcystin released by the decomposition of the algae is removed. It is a method for treating algae, which is characterized by contacting with Sphingomonas bacterium to render it harmless. In addition, a liquid containing algae is contacted with a Brevibacillus-type algae to destroy or decompose algae, and then microcystin released by the decomposition of the algae is contacted with Sphingomonas and detoxified. , A method for treating algae, which comprises contacting with activated sludge under aerobic conditions to remove BOD components. The Brevibacillus-type lytic microorganism and / or Sphingomonas bacterium is a porous carrier in which 10 ⁵ cells / cm ³ or more of the carrier are supported, respectively. .

Although one example of steps for carrying out the present invention is shown in FIG. 1, the present invention is not limited thereto. The water containing water-bloom is taken in, and necessary pretreatments such as dust removal and flow control are performed, and then introduced into the algae algae dissolving process. In the algae-dissolving step, a carrier in which Brevibacillus bacteria have been cultivated and carried on a carrier has been added in advance, and Brevibacillus destroys the cell membrane of water-bloom. Next, the process for decomposing the microcystin eluted from the inside of the water-bloom cell is proceeded. In this process, the Sphingomonas bacterium is cultured and brought into contact with the carrier-supported one. Even in the microcystin decomposition process, B
Although the OD is reduced, the treated water with high cleanliness is released by adding the BOD decomposition step in the latter stage.

The present inventors have examined the lysis mechanism of Microcystis by substances produced by Brevibacillus and Streptomyces actinomycetes (antibiotics-like low molecular weight compounds), and the lysis rate increases the microbial cell concentration. To increase rapidly. In addition, the degradation of microcystin LR is caused by an enzyme secreted by Sphingomonas. 2m concentration
g / L of microcystin LR was added to Sphingomonas and 2
1 μg / L which is the standard of WHO by contacting for 4 hours
Be able to: Further, the BOD component produced by the decomposition of microcystis is ingested by Sphingomonas bacterium, and the activity maintenance period can be extended to 2 months or more, which is practically preferable. Brevibacillus bacteria and Sphingomonas bacterium is 10 ⁵ to a porous support / cm ³ when the carrying or support its activity is enhanced, yet the recovery was completed newly found by the present invention such that the reproduction is easy.

The Brevibacillus bacterium used in the present invention is obtained by collecting the bottom mud of Lake Tsukui, located in Tsukui-gun, Kanagawa Prefecture, culturing and separating it on an agar medium, and then performing integrated culture. Brevibacillus deposits at the National Institute of Advanced Industrial Science and Technology, Institute of Biotechnology and Industrial Technology are as follows. Microorganism display: (Display for identification given by the depositor)
Brevibacillus sp. B1-A (consignment number) FERM
P-18213 Receipt and deposit: The medium used for depositing on February 20, 2001 was glucose 0.5 g /
L, polypeptone 2 g / L, yeast extract 1 g / L, agar 15 g / L Sakurai medium. The 16S rRNA gene nucleotide sequence of the deposited bacterial cell B1-A was measured, and the result was searched by the homology search system FASTA of the National Institute of Genetics,
NIG Action No. D78460 Brevibacillus for
This cell was identified as Brevibacillus because it showed 98.512% homology with mosus. The 16S rRNA gene nucleotide sequence is shown in Table 1 for reference.

[0012]

[Table 1]

The present bacterium is a bacillus and is a gram-positive aerobic bacterium. Movement is by flagella. Sex spores swell and form sporangia. Ten colonies are smooth, yellowish gray and do not produce soluble pigment on nutrient agar.

Brevibacillus used for the algae-dissolving reaction is cultivated by dissolving 2 g of peptone, 1 g of yeast extract and 0.5 g of glucose per 1 L of the culture solution in a tank equipped with an air diffuser and agitator, and pre-isolating it. Brevibacillus of the seed culture solution that had been cultivated was added, and the mixture was cultured at a temperature of 27 ° C. with gentle aeration and stirring. When the cell concentration reached 10 ⁶ cells / mL or more, the porous carrier was soaked and left for 12 hours or more to support Brevibacillus bacteria carrying 10 ⁵ cells / cm ³ carrier or more. A porous carrier is obtained. The cultivated high-concentration cell-containing solution may be directly sprayed on the solution containing blue-green algae, but when it is supported on a porous carrier such as foamed polyester, a high cell-concentration region is formed on the carrier surface. Therefore, the algae reaction is actively performed here. The test carrier having 2 × 10 ⁴ cells / cm ³ carrier to 1 × 10 ⁷ cells / cm ³ carrier of Brevibacillus carried was immersed in a solution having a content of 10 ⁷ cells / mL for 12 hours. The rate of algae is shown in FIG. The amount of Brevibacillus carried is 1
0 ⁵ pieces / cm ³ or more, preferably 5 × 10 ⁵ pieces / cm ³
When maintained above the carrier, the rate of algae was 70% or more on average, but when the number of bacterial cells decreased, the rate of algae decreased sharply. It should be noted that the carrier having a small number of cells can be added to the culture tank again to increase the number of cells.

The concentration of water-bloom (blue algae) can be measured from the concentration of chlorophyll a. The relationship between the concentration of cyanobacteria and the concentration of chlorophyll a measured in the field test (field data) at Lake Tsukui and in the laboratory is almost linear as shown in Fig. 3, and the concentration of cyanobacteria is determined from the measured value of chlorophyll a. can do. As a carrier for Brevibacillus, in addition to expanded polyethylene, materials used in water treatment such as expanded polypropylene, polyester, urethane, activated carbon, bamboo charcoal, wood chips, cellulose, silicate balloons, urethane rubber, etc. are adopted according to their usage. can do. The shape is not only granular but also plate-like, net-like, string-like,
A shape that is easy to use, such as a rod shape or a cylindrical shape, can be appropriately selected. The bacterial cells are easily supported by the adhesive type, but the bacterial cells are entrapped and immobilized by adding a culture component to the hydrogel, and the effective period can be maintained longer than that of the adhesive type. A hydrous hydrate, etc. obtained by adding a flocculant to a culture solution of Brevibacillus is strongly preferable as an algae reaction due to a strong bond between a hydrate and water-bloom, but cannot be regenerated and used. .

Since the raw water containing water-bloom is usually mixed with dust, contaminants are removed by a screen or the like, and the water is agitated at high speed if necessary to destroy the water-bloom aggregate covered with the polysaccharide film. Then, in the algae reaction performed in the next step, it is preferable to facilitate the direct contact of Brevibacillus as the algae substance with the water-bloom cells. The concentration is low in the early stages of water-blooming, and some water-blooms do not float to the surface of the water but float in the water. In this case, the capacity of the reaction tank can be reduced by concentrating the water-bloom using a decanter or a centrifuge. The algae-dissolving step is not particularly limited by the type and system of the reaction tank, as long as the solution containing agitation-treated algae is brought into contact with Brevibacillus bacteria. Preferably, a carrier having a specific gravity of about 1 is suspended in the liquid, air is blown from the bottom of the tank, and the mixture is gently stirred. Another method is to deposit the carrier and bring the liquid into pump contact with the deposited layer,
Those that use a lattice-shaped or plate-shaped carrier, especially a membrane reactor in which a membrane such as MF or RO is provided at the outlet on the treated water side by contacting it with a carrier of light specific gravity is also suitable as a water source facility for tap water. is there.

The step of degrading microcystin is carried out by contacting the solution in which the cell membrane of water-bloom is destroyed with a carrier carrying Sphingomonas bacterium. About 6 types of microcystin have been detected in Japanese watermelon,
The structure is classified as shown in Table 2 with the basic unit shown in the chemical structural formula (1). The symbol abbreviations are also shown below Table 2.

[0018]

[Chemical 1]

[0019]

[Table 2] Ala: D-alanine β-MeAsp: D-β-methylaspartic acid Adda: 3-amino-9-methoxy-2,6,8-trimethyl-10-phe
nyldeca-4,6-dienoic acid Glu: D-glutamic acid Mdha: N-methyldehydroalanine Arg: L-arginine Leu: L-leucine

The Sphingomonas bacterium used in the present invention is
Lake water of Lake Tsukui, located in Tsukui District, Kanagawa Prefecture, was collected, cultivated / separated on an agar medium, and concentrated and cultivated, and it works effectively for any of the microcystins in Table 2 above. The deposits of Sphingomonas sp. To the National Institute of Advanced Industrial Science and Technology, Institute of Biotechnology and Industrial Technology are as follows. Labeling of microorganisms: (Display for identification by the depositor) Sphingomonas sp.
B9) (Consignment number) FERM P-18212 Receipt and consignment: February 20, 2001 Medium composition is glucose 0.5 g / L, polypeptone 2
It is a Sakurai medium consisting of g / L, yeast extract 1 g / L, and agar 15 g / L. Sphingomonas SP B 9
Table 3 shows the nucleotide sequence of 16S rRNA gene of (Sphingomonas sp. B9).

[0021]

[Table 3]

Based on the nucleotide sequence, Sphingomonas spp., Related alpha-proteobacteria (α-Proteoba
From the phylogenetic tree by the neighbor-joining method with the bacterial species, the bacterial species entered the Sphingomonas cluster. In addition,
This genus is a gram-negative bacterium, a linear bacillus that does not form spores, has a single polar flagella for movement, and is a true aerobic bacterium. A colony has a lemon yellow color when it appears, and when it disappears, the color also disappears, so the presence can be easily identified.

Sphingomonas is a yellowish fungus and becomes colorless when the microcystin-degrading enzyme is consumed. Sphingomonas bacterium does not easily propagate in general lake water, and considering the outflow from the reaction tank, it is necessary to add a carrier carrying new cells in about 20 days. However, it was found that, when algae were killed in the previous stage, the activity of Sphingomonas ingested BOD components released from the body of the algae and the activity maintenance period was extended. That is, by changing the BOD concentration in a constant concentration microcystin solution,
The result of having measured the activity maintenance period of Sphingomonas is shown in FIG. When the BOD component concentration is 2 mg / L or more, the activity of Sphingomonas bacterium is slightly increased and the life span is significantly extended.
It is preferable to carry out under conditions of g / L or more. In addition, when it is necessary to remove the BOD component contained in the treated water from the beginning or released in the algicidal stage, it is preferably performed after the microcystin decomposition step.

Cultivation of Sphingomonas bacterium was carried out in a tank equipped with an aeration and stirring device, 2 g of peptone per liter of culture solution,
1 g of yeast extract and 0.5 g of glucose were dissolved, to which Sphingomonas bacterium, which was a seed culture solution that had been isolated and cultured in advance, was added, and the mixture was cultured at a temperature of 27 ° C. with gentle aeration and stirring. When the porous carrier was soaked when the cell concentration reached 10 ⁶ cells / mL or more and left for 12 hours or more, the Sphingomonas bacteria carrying 10 ⁵ cells / cm ³ or more of the cells were carried. A porous carrier is obtained. For culturing Brevibacillus or Sphingomonas, natural media such as molasses and constiplica can be inexpensively used, but a semi-synthetic medium in which a natural medium and a synthetic medium are combined may be used, or a simple synthetic medium may be used. In particular, it is preferable to use a synthetic medium and then use a natural medium since it is difficult to set up at the initial stage of culture.

When a porous carrier such as foamed polyethylene is immersed in the cultured high-concentration cell-containing liquid, a region of high cell concentration is formed on the surface of the carrier, so that the decomposition reaction of microcystin occurs here. Actively performed. 2 × cell concentration
FIG. 5 shows the decomposition rate when the test carriers of 10 ⁴ / cm ³ carrier to 5 × 10 ⁶ / cm ³ carrier were immersed in a solution having a microcystin concentration of 200 μg / L for 12 hours. The decomposition rate of microcystin was 80% or more when the amount of Sphingomonas bacterium carried was 1 × 10 ⁵ cells / cm ³ or more, but the lysis rate decreased when the number of cells decreased, so the carrier concentration was high. The performance is restored by returning it to the culture tank and reloading it. Regarding the carrier, the supporting method and the reaction tank, the treatment method of Brevibacillus can be applied correspondingly.

[0026]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below with reference to the drawings. FIG. 6 is a diagram illustrating an example of the processing system of the present invention. Raw water containing water-bloom is sent to the stirring tank (10) through the raw water pipe (12). In addition,
A screen (14) is provided at the inlet to remove foreign matter such as wood chips. A plurality of agitators (1
7) There is a continuous or intermittent rotation to homogenize the liquid to be treated.

The liquid to be treated is a pipe (19) and a liquid feed pump (2).
1), it is sent to the first algae bath (30-1).
The algae baths (30-1), (30-2) and (30-3) have almost the same shape (100 L x 3 baths), but the flow direction of the liquid to be treated is that the first bath is upward. Then, the next flows downward and then upward again to enhance the contact between the liquid and the carrier. Inside each algae tank, there is an air diffusion pipe (34) at the bottom.
A cage (32) accommodating a foamed polyethylene carrier 30L carrying Brevibacillus bacteria is stored in the upper part thereof. The cage (32) containing the carrier carrying Brevibacillus was placed in a Bacillus culture tank (40) having a capacity of 100 L in advance, and a sufficient amount of Brevibacillus was formed on the surface of the carrier under conditions suitable for culture of Brevibacillus. Bacillus is attached. The cage (32) storing the carrier may be reciprocated between each of the algae baths (30-1), (30-2) and (30-3) and the Bacillus culture tank (40). It is also possible to use the circuit sequentially in sequence as shown by the arrow in FIG. The concentration of cyanobacteria including water-bloom can be known from the measurement of the concentration of chlorophyll as shown in FIG.

The water to be treated that has flowed out of the algae bath (30-3) passes through the pipe (23) and then flows into the microcystin decomposition bath (54) of 100 L capacity. The microcystin decomposition tank (54) has an air diffuser (34) and a 30 L sphingomonas-supporting carrier storage basket (52), which decomposes microcystin contained in the water to be treated to render it harmless. The sphingomonas carrier storage basket (52) is also placed in the sphingomonas culture tank (50) in advance so that bacterial cells are attached or adsorbed to the surface of the carrier. The treated water treated with microcystin is put into the post-treatment tank (60) from the pipe (56), aerated there, and then discharged from the discharge pipe (62).

The reaction conditions in each of the algae bath and the microcystin decomposition bath are as follows. Apparent packing rate of carrier is 1
The amount of air blown was 3 L / min per 100 L of water to be treated, the average water temperature was 27 ° C., and the amount of dissolved oxygen was 4.5 mg / L on average. In addition, since the liquid was not sufficiently stirred only by blowing air, a vertical flow of the liquid was formed by a mechanical stirrer.

The culture conditions in the Bacillus culture tank are as follows: 2 g of peptone / L of culture medium and 1 yeast extract.
g and glucose 0.5 g were dissolved, and Bacillus bacteria of a seed culture solution that had been isolated and cultured in advance were added thereto, and the mixture was incubated at a temperature of 27 ° C. with gentle aeration and stirring. Cell concentration is 10
^{When the} number reached ⁶ cells / mL or more, the expanded polyethylene carrier was immersed and left standing for 24 hours to support Bacillus bacteria on the porous carrier.

The culture conditions and confirmation of the culture in the Sphingomonas culture tank (50) are as follows. Add 2 g of peptone and 1 g of yeast extract per liter of culture solution,
Spray Sphingomonas spp. Isolated from lake water at 27 ℃
Culturing was carried out at a temperature of, with gentle aeration and stirring. When the cell concentration reached 10 ⁷ cells / mL, the porous foamed polyethylene carrier was immersed and left for several days to support Sphingomonas bacterium on the porous carrier. Since Sphingomonas has an orange-yellow color, it is possible to determine the approximate concentration also from the chromaticity, but it is possible to accurately analyze it from the absorbance at a wavelength of 660 nm.

In the example of the present invention, using the apparatus shown in FIG. 6, a decomposition treatment test of water-bloom taken from lake water in the Kanto region was carried out for about 80 days. Raw water containing water-bloom is fed once a day on weekdays, retained in the algae bath for 3 days, and retained in the microcystin decomposition bath for 1 day and discharged. The results are shown in FIGS. 7 and 8. The average concentration of cyanobacteria in the water to be treated entering the algae bath (30-1) was 10 ⁷ cells / mL, and the outlet concentration of the third tank (30-3) was reduced to about 250 cells / mL. The microcystin concentration in the water to be treated flowing into the microcystin decomposition tank (54) was 80 to 100 μg / L, and the outlet concentration after treatment was 1 μg / L or less over 50 days. Since this microcystin concentration was diluted at the discharge destination and gradually decomposed in the natural environment, it was at a level at which there was no problem as environmental water. The TOC of the raw water collected in the raw water pipe (12) is about 1 mg / L, and the BOD is 0.5 m.
It was estimated to be about g / L. The BOD of the treated water in the treated water pipe (23) after the algae reaction is 4.5 to 5.5 mg / L
Although included, the outlet discharge pipe (6) of the rear aeration tank (60)
The discharged water of 2) had a BOD of 2 mg / L or less, which was a level with no problem in discharging.

[0033]

EFFECTS OF THE INVENTION As is clear from the detailed and specific description above, the treatment system for blue-green alga of the present invention cultivates Brevibacillus spp. Since it is used, there is no concern about secondary pollution of the environment due to the materials used, and it is possible to detoxify algal killing of water-bloom and toxic components that accompany it. In addition, nitrogen and phosphorus can be removed by the action of activated sludge generated in the algae bath and the microcystin decomposition bath, and improvement in water quality can be expected.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an example of a process of the present invention.

FIG. 2 is experimental data relating to the loading amount of Brevibacillus on the rate of algae.

FIG. 3 is a relationship diagram showing the number of cyanobacteria and chlorophyll concentration.

FIG. 4 is a diagram showing changes in the activity maintenance period of Sphingomonas depending on the concentration level of BOD components.

FIG. 5 is a relational diagram of the number of bacterial cells carried on a carrier, which affects the decomposition rate of microcystin.

FIG. 6 is a device layout diagram illustrating an example of a system configuration of the present invention.

FIG. 7 is a diagram in which the numbers of cyanobacteria in the inlet and outlet waters of the algae bath used in the examples of the present invention are measured.

FIG. 8 is a diagram showing the measured microcystin concentrations in the inlet and outlet waters of the microcystin decomposition tank used in the examples of the present invention.

[Explanation of symbols]

10 stirring tanks 12 Raw water piping 14 screen 17 Stirrer 19 plumbing 21 Liquid transfer pump 23 Piping 30-1 Algae tank 30-2 Algae tank 30-3 Algae bath 32 Brevibacillus carrying carrier storage basket 34 Air diffuser 40 Brevibacillus culture tank 50 Sphingomonas culture tank 52 Sphingomonas carrier basket 54 Microcystin Degradation Tank 56 piping 60 post-treatment tank 62 Discharge pipe

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) // (C12N 1/20 C12R 1:01 C12R 1:01) (72) Inventor Kiyomi Tsuji Shinjuku-ku, Tokyo Haramachi 3-18 F term (reference) 4B065 AA01X BA22 BC42 CA56 4D003 AA01 AB02 BA04 EA06 EA14 EA17 EA19 EA21 EA25 EA28 EA30 FA02 FA06 4D040 DD03 DD31

Claims (3)

[Claims] 1. A liquid containing algae is brought into contact with a Brevibacillus-type algae to decompose it, and then microcystin released by the decomposition of the algae is brought into contact with Sphingomonas bacterium to render it harmless. A method for treating algae characterized by: 2. A liquid containing algae is contacted with a Brevibacillus-type algae to be decomposed, and then microcystin released by the decomposition of the algae is contacted with Sphingomonas bacterium to be harmless. , A method for treating algae, which comprises contacting with activated sludge under aerobic conditions to remove BOD components. 3. The Brevibacillus-type algae-producing microorganism and / or Sphingomonas bacterium are each carried on a porous carrier in an amount of 10 ⁵ cells / cm ³ or more, respectively. The method for treating algae according to 1.