JPH0415036B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a method for removing underwater algae. More specifically, the present invention relates to a method for removing algae in water, and more specifically, it removes algae such as blue-green algae that occurs in closed water bodies such as lakes and reservoirs. Concerning how to effectively remove it with time. (Prior Art) In recent years, large amounts of blue-green algae have been occurring in Japan's representative lakes such as Lake Biwa, Lake Suwa, and Lake Kasumigaura. The negative effects of large amounts of blue-green algae are as follows. (1) Detracts from the beauty of the water area, (2) Generates a peculiar odor (rotten odor), (3) Kills animals and plants in the middle and lower levels, (4) Damages purification equipment, (5) Chlorine Deterioration of drinking water due to sterilization. Traditionally, to remove blue-green algae that occurs in lakes and marshes, the following methods have been used: (1) Purification by introducing water from rivers, etc., (2) Purification by creating a flow and fluidization, (3) Purification by various aeration methods, and (4) Pumping water. Purification through plant treatment and (5) purification through recovery are being carried out. In addition, algae control agents are also applied to rice fields, small ponds, etc. (Problems to be Solved by the Invention) However, conventional purification methods are still not fully satisfactory in terms of their removal effect on algal blooms, and also have drawbacks such as complicated treatment and extremely high treatment costs. Ta. Application of algae control agents is quite effective in removing blue-green algae, etc., but it has an adverse effect on organisms in the water column, and the treatment costs are enormous for large areas of lakes and marshes, so it cannot be put to practical use. Therefore, an object of the present invention is to provide a method that can effectively separate and collect algae such as algal blooms that occur in closed water bodies, together with phosphorus that causes the occurrence of blue-green algae. Another object of the present invention is to treat algae such as blue-green algae as living flocs by using a treatment agent that is relatively inexpensive and does not have a negative effect on other organisms coexisting in closed water areas. The object of the present invention is to provide a method that allows easy separation and flotation and collection. (Means for solving the problem) According to the present invention, clay minerals and
A treatment agent consisting of a powdered reaction product of 10 to 90 equivalents of inorganic acid based on Al ₂ O ₃ and Fe ₂ O ₃ components is added to water containing algae, and flocs of the treatment agent and algae are removed. There is provided a method for removing underwater algae, which is characterized by forming flocs, floating the flocs, and separating and removing the flocs. (Function) The powder of the clay mineral-inorganic acid reaction product effectively collects algae such as blue-green algae existing in water, and forms large and strong flocs without killing the blue-green algae. This is based on the discovery that algal blooms can form flocs and that these flocs can float to the surface of the water and become concentrated due to the gases emitted by the algal blooms themselves. The present inventors have already proposed that a water-soluble aluminum salt aggregates algae in water to form a floc (patent pending), but the clay mineral-inorganic acid reaction product used in the present invention The powder has a significant advantage over the aforementioned water-soluble aluminum salts in that it can form larger and stronger flocs of algae. This floc rises to the surface of the water due to the gas released by the blue-green algae itself;
Since the process progresses by capturing and filtering out substances floating on the way, the remarkable feature is that the purified water after floating to the flocs becomes extremely clear. Furthermore, it is known that blue-green algae emit a bad odor when it dies, and also give off a strange odor to the water. According to the present invention, the algae, while still alive, turns into flocs and floats to the surface, producing a bad odor. Moreover, the water quality is maintained at a good level, and has excellent advantages in terms of water purification of lakes and marshes, water quality conservation, and environmental conservation. Especially when using water from lakes, reservoirs, etc. for drinking,
Large amounts of chlorine must be used to reduce the odor caused by algae, and the production of trihalomethanes, which are carcinogenic (mutagenic), has become a social problem, but the method of the present application can fundamentally solve this problem. resolved to. The flocs of blue-green algae floating on the surface of the water are extremely dense and small in volume, and it is very easy to separate and collect them. This is because the above-mentioned clay mineral-inorganic acid reaction product causes the blue-green algae to firmly aggregate into flocs, and the blue-green algae itself releases gas in its bubbles.
This is probably due to the fact that it is concentrated. Furthermore, the clay mineral-inorganic acid reaction product used in the present invention has the property of fixing phosphorus present in water, so it can fix algae and other suspended matter, as well as the phosphorus accumulated in the algae itself and the water. Dissolved phosphorus and other components can be removed and purified at the same time. Therefore, by carrying out the treatment of the present invention, it is possible to eliminate the causes of algal blooms in lakes and marshes. The processing agent used in the present invention is obtained by reacting a clay mineral with an inorganic acid. Examples of clay minerals include acid clay, bentonite, subbentonite, montmorillonite group clay minerals such as furous earth, other smetite group clay minerals such as beidellite, nontronite, volkonskoite, sabonite, and sauconite, and pyrophyllite such as pyrofluorite. Any clay mineral can be used, such as kaolin clay minerals such as light group clay minerals, kaolinite, halloysite, and hydrated halloysite. Among these clay minerals, clay minerals with a specific surface area of 50 m ² /g or more, such as smectite group clay minerals,
In particular, montmorillonite group clay minerals are suitable for the purposes of the present invention. Among the above-mentioned clay minerals, smectite group clay minerals have a three-layer structure in which two SiO ₄ tetrahedral layers are sandwiched with an AlO ₆ octahedral layer in between, and this basic three-layer structure is further developed. It has a structure in which many layers are stacked in the C-axis direction, and kaolin group clay minerals have a multi-layer structure based on a two-layer structure consisting of a SiO ₄ tetrahedral layer and an AlO ₆ octahedral layer. .
Among the skeletons of these clay minerals, the alumina component and the base component present in a form substituted for the alumina component or between the layers are involved in the reaction with the acid. As the inorganic acid, sulfuric acid is most suitable from the point of view of economy and handling, but other mineral acids such as hydrochloric acid, phosphoric acid, and nitric acid can of course be used, and others can react with the alumina component in the clay. Any acid as long as it is
For example, phosphorus and sulfur oxyacids other than those mentioned above can be used. In the case of polybasic acids, partially neutralized basic salts can also be used.
Furthermore, the acid extract produced as a by-product when clay minerals and the like are treated, that is, the free acid in the extract, may be reused for the reaction with clays. In the present invention, the inorganic acid is
10 to 90 equivalent % based on Al ₂ O ₃ and Fe ₂ O ₃ components, especially
It is also important to use amounts of 20 to 80 equivalent %.
That is, when the amount is less than the above-mentioned ratio, the tendency to agglomerate and flocculate blue-green algae is insufficient, and when it is more than the above-mentioned ratio, it becomes difficult to handle as a powder and the price becomes high. The reaction between the clay mineral and the inorganic acid is easily carried out by kneading the inorganic acid into the clay mineral and, if necessary, drying the kneaded composition. In order to carry out the reaction homogeneously, it is desirable to carry out both in the presence of water, and this water may be present in the acid or water contained in the clay mineral may be used. The reaction proceeds satisfactorily at room temperature, but the heat during drying can also be used for the reaction. As the reaction progresses, an aluminum salt of the inorganic acid is formed, and as a result, the specific surface area of the powdered reaction product generally decreases rapidly. From the viewpoint of flocculation performance against blue-green algae and not significantly lowering the pH of the treated water, the amount of free acid in the reaction product should be determined as a 10% aqueous suspension.
It is preferably 0.1 g/100 ml or less when titrated with a 0.1N NaOH aqueous solution. In addition, from the standpoint of increasing dispersibility in water and effectively floating the formed blue-green algae flocs on the water surface, it is preferable that the reaction product be as fine as possible, and should pass 200 meshes (Tyler standard). It is desirable to have particle size characteristics such that the content is 50% by weight or more, particularly 60% by weight or more. Although the reason why the powdered reaction product of the present invention forms strong and large flocs of algae has not yet been fully elucidated, the present inventors speculate that the reason is as follows. Clay minerals form a tetrahedral layer of SiO ₄
As mentioned above, this AlO ₆ octahedral layer reacts with the inorganic acid to form its salt, but _{the SiO 4 tetrahedral} layer remains as it is. it seems to do. When this is poured into water, algal blooms are collected through the hydrolysis reaction of the formula Al ³⁺ →Al(OH) ₃ , but it is believed that strong, large flocs are formed with layered silica as the core. It will be done. The treatment agent of the present invention is preferably added to algae-containing water in an amount of generally 50 to 1000 ppm, particularly 100 to 400 ppm. Addition to algae-containing water is preferably carried out in powder form. The treatment method of the present invention is applied to lakes and marshes where algal blooms have occurred;
Perform directly on the water surface of a pond, reservoir, etc. In this case, it is preferable to stir and mix the blue-green algae-containing water and the treatment agent. A submersible stirrer is used for this purpose. When water containing blue-green algae and the treatment agent are mixed, the flocs of blue-green algae that are formed either settle first or
The algae itself becomes suspended due to the gas it produces. Although the floating of blue-green algae flocs varies depending on the temperature of the raw water and other factors, it generally starts 1 to 5 minutes after addition. In addition, blue-green algae floating on the water surface,
It was confirmed that the cells remained viable for 2 to 3 days after addition. Therefore, after floating the blue-green algae flocs, it is best to separate them from the purified water and collect them while they are still alive. In the former case, this separation collection involves scraping,
This can be carried out by suction or the like, and in the latter case, a flotation separation device known per se can be applied. Although the present invention has been described using algal blooms as an example, it should be understood that it is also effective for removing diatoms and other orchids. (Effects of the Invention) According to the present invention, by using a treatment agent that is available at a relatively low cost and does not have an adverse effect on other organisms,
This method has the advantage that algae such as blue-green algae can be separated and floated as living concentrated flocs, and phosphorus, which causes blue-green algae, can be removed at the same time, making water purification extremely effective. (Example) Example 1 As the raw acid clay, acid clay produced in Odo, Shibata City, Niigata Prefecture and having the composition shown below was selected. In its natural state, the acid clay raw material contains about 40% water by weight, and its main component is 110% by weight on a dry matter basis.
℃ dry), SiO ₂ 73.0, Al ₂ O ₃ 14.1, Fe ₂ O ₃ 3.8,
MgO3.0, CaO1.2, ignition loss 5.9, specific surface area 100
m ² /g. This acid clay was dried at 110°C, then crushed, concentrated sulfuric acid equivalent to 60% of the equivalent of the basic components of alumina and iron oxide (Al ₂ O ₃ , FeO ₃ ) contained in the acid clay was added, and thoroughly kneaded. After granulation, it was dried and pulverized to obtain sample A of the underwater algae remover. Therefore, in order to confirm the algae control effect of Sample A, the following experiment was conducted. Water from the moat with a temperature of 15.5℃, pH of 9.73, and turbidity of 48.0 was collected from Lake A and used as raw water. 1000 c.c. of the collected raw water was placed in a graduated cylinder, 200 mg and 400 mg of sample A were added, and after shaking and stirring 5 times, the formation of flocs and floating separation of blue-green algae was observed. After the experiment, turbidity (TV), PH, total phosphorus,
Each item of dissolved phosphorus was analyzed and compared with raw water. The results are shown in Table-1. Each measurement item was performed using the following method. PH: Glass electrode method Turbidity: Spectrophotometry Transparency: JIS K 0102 Total phosphorus: Pretreatment: Persulfuric acid decomposition method Analysis method: Molybdenum blue method Dissolved phosphorus: Molybdenum blue method

[Table] Example 2 Pond water with a temperature of 14.6°C, a turbidity of 35.0, and a pH of 10.43 was collected from Lake B and used as raw water. Table 2 shows the results obtained using the same method as in Example 1.
Shown below. A similar test was conducted using a sulfuric acid solution (0.1 normal concentration) and a sulfuric acid band solution (1% concentration) as comparative test samples.

【table】

Claims (1)

[Claims] 1. A treatment agent consisting of a powdered reaction product of a clay mineral and an inorganic acid of 10 to 90 equivalent % based on the Al ₂ O ₃ and Fe ₂ O ₃ components in the clay mineral is added to water containing algae. 1. A method for removing algae in water, which comprises: adding the treatment agent to the algae to form a coagulated floc of the algae, floating the floc, and removing the coagulated floc. 2. The method according to claim 1, wherein the processing agent has a particle size that contains 50% by weight or more of the amount passed through 200 meshes. 3 The processing agent is 0.1g/100ml as a 10% aqueous suspension, measured with a 0.1N aqueous sodium hydroxide solution.
A method according to claim 1, comprising a powdered reaction product having a free acid content of: 4. The method according to claim 1, wherein the treatment agent is added in an amount of 50 to 1000 ppm per algae-containing water.