JPH08257591A - Removal of water-bloom and method and device for controlling abnormal generation thereof - Google Patents

Abstract

PURPOSE: To provide a method and a device for removing water-bloom and controlling its abnormal generation which is impossible in a conventional method by rapidly and simultaneously removing organic phosphorus an inorganic phosphorus in water being the nutrient source of water-bloom out of water. CONSTITUTION: In a method for removing water-bloom in the water area and controlling its abnormal generation, an ultraviolet ray irradiation method is combined with a treatment for bringing water in the water area in which water- bloom is generated into contact with a magnesium ion-supplying agent and with a biological treatment method.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for removing water-bloom generated in a water body and suppressing its abnormal occurrence.

[0002]

2. Description of the Related Art In recent years, closed water areas such as lakes and marshes, which have a large pollution source in the hinterland, are subject to eutrophication due to the large inflowing pollutant load and the accumulation of pollutants. Abnormality has occurred and has become a social problem. Abnormal occurrence of blue-green algae in the lakes and marshes of tourist areas impairs the landscape and also causes offensive odors, reducing the value as a tourist resource. Even in lakes, which are the source of drinking water, freshwater red tides and water-blooms are abnormally occurring, which causes problems of filtration problems and offensive odors in water supply facilities.
Furthermore, problems such as the generation of carcinogens due to chlorine disinfection carried out at water supply facilities have been pointed out. In order to deal with these issues, the Water Pollution Control Law, the Law for Special Measures for Lake Water Quality Conservation, and the drainage regulation of nitrogen and phosphorus related to lakes have been established and implemented.

The main countermeasures against the problems caused by the abnormal occurrence of blue-green algae are to prevent the inflow of pollutants including nutrient salts, to remove the bottom mud of the eutrophic closed water area, and to directly remove the abnormal blue-green algae. A method of removing it has been proposed. Regarding these, it is impossible to fully implement them at this time, because they can be achieved only by suspending or suppressing all the production activities including humans.
With regard to (2), it is difficult to carry out the dredging and the treatment of the residual soil because of the huge cost and the large number of target lakes. Therefore, at the present time, the most effective method for removing blue-green alga is to be implemented. Further effective methods for removing the generated water-bloom include direct filtration, biodegradation, and ultraviolet irradiation.

[0004]

[Problems to be Solved by the Invention] Among the methods for removing the generated water-bloom, the direct filtration method is sand filtration, ultrafiltration, precoat filter, long hair type filter etc. It is a method of filtering the whole amount. The direct filtration method has the drawbacks of being severely clogged and not applicable to large lakes. Although the biodegradation method of E. coli is effective for temporary removal of water-bloom, it cannot control the generation of water-bloom. This is because the nutrients produced by decomposing and mineralizing water-bloom by the biological method again cause the generation of water-bloom. The ultraviolet irradiation method is a method of irradiating a blue-bloom with ultraviolet rays to kill algae. At present, it is considered to be the most effective method, but it has a drawback that the cost of UV irradiation is high. Therefore, taking measures against water-bloom using only these methods has problems in terms of cost and effects after implementation.

On the other hand, various studies have been conducted on the mechanism of abnormal development of water-bloom, and it is known at present that it is caused by excessively accumulated phosphorus (P) and nitrogen (N). Murakami et al., Environmental Technology, Vol. 19, No. 2, (199
0), pp. 88, lines 7-9, "Of the substances that stimulate the growth of algae and cause eutrophication, it has been clarified that N and P are important regulators. It is the most important thing for the water quality conservation of the water area to strongly push the measures to reduce the inflow of N and P. ", and it is necessary to prevent the inflow of N and P to suppress the generation of water-bloom. There is. Iwai also similarly gypsum and lime, Vol. 410, No. 2, (19
90), p. 1, lines 10-11, "But in terms of water quality, phosphorus
(P) and nitrogen (N) are the main factors, and biological stimulants (certain metals) and vitamins, etc. are the secondary factors. ”, And pointed out that N and P are the factors that cause the blue-green algae. There is. Also,
It has also been pointed out that P is a priority factor among the domestic algal development factors. Therefore, if P in the closed water area can be reduced, it is possible to suppress the abnormal occurrence of water-bloom.

Regarding the reduction of phosphorus in the water body, it is important that the reduction of the inflowing phosphorus and the reduction of the phosphorus in the inflowing water body are carried out at the same time. However, it is difficult to deal with the reduction of inflowing phosphorus at the present time for the reasons described above, so it is necessary to deal with the reduction of inflowing phosphorus. As a method of reducing the inflowing phosphorus, various adsorbents and adsorption removal methods have been proposed. In JP-A-60-110393, an adsorbent having a magnesium salt and a calcium salt adhered to the surface of a granular solid substance is disclosed, and in JP-A-4-200788, a mixture of calcium silicate hydrate and a magnesium compound is disclosed.
4-180884 discloses a lime-based adsorbent. Among these adsorbents, lime-based adsorbents have been regarded as promising because they are inexpensive and can be easily applied. However, in reality, it is becoming clear in recent reports that it is difficult to achieve effective results.

The lime addition method is a method in which lime is added to a body of water in which water-bloom abnormally occurs, and lime reacts with phosphorus to form a sparingly soluble phosphate compound, and phosphorus, which is a nutrient source for water-bloom, is fixedly removed. is there. However, the following problems have been pointed out in the lime addition method. Since lime reacts with carbonate ions existing in water to form and stabilize calcium carbonate on the surface of lime, there is a drawback that supply of calcium ions is stopped. Regarding this, in JP-A-4-200788,
It is also clear from the fact that it is pointed out that the reactivity of calcium ion and carbonate ion is higher than the reactivity of calcium ion and phosphate ion. Furthermore, since lime has a relatively high solubility, it has a characteristic that the indicated pH is high when it is put into water. Therefore, in the case of administration, it is necessary to consider the change in pH of the environmental water, which increases by administration, from the viewpoint of the effect on the living body. In particular, in a fresh water system having a low pH buffering capacity, it is necessary to carefully administer. In this regard, Takashima et al.
4), p. 61, lines 21-22, "In lime administration, p
It is necessary to reconsider the amount added, paying attention to H. ”, and the effect obtained by administration is also important, but it is important to maintain the pH of environmental water after administration within the environmental standard pH. That is.

[0008] Therefore, as a result of diligent research, the present inventors have focused their attention on the behavior of phosphorus, which is indispensable for the growth of plants in lakes where eutrophication is progressing, and lakes where eutrophication is progressing. The amount of phosphorus existing in the water in the seawater is higher than that of soluble inorganic phosphorus by organic production, and the removal of water-bloom by the conventional biodegradation method is due to the mineralization of organic matter using microorganisms. Since the mineralized phosphorus remains in water, it becomes a nutrient source for the growth of water-bloom again. The form of phosphorus required as a nutrient source varies depending on the type of water-bloom. Inorganic adsorbent including lime addition method. Inorganic phosphorus is the only phosphorus that can be adsorbed and removed by means of water, and it is almost impossible to remove organic phosphorus. The main purpose of algal killing is to remove blue-green algae by UV irradiation, etc. There is no effect on the amount of emissions, to discover facts equal, leading to the invention the method. That is, organic phosphorus remains in the treatment method using the inorganic absorbent alone, and it is difficult to remove the inorganic phosphorus in the treatment method using algae killing by ultraviolet irradiation or the biodegradation method alone. Therefore, since these are supplied as nutrients for water-bloom and cause the generation of water-bloom again, the biodegradation method that has been performed so far, or the conventional method alone such as the adsorbent alone,
It is considered that the full effect was not always obtained against the water-bloom.

[0009]

DISCLOSURE OF THE INVENTION The present invention provides a method for removing water-bloom and suppressing the abnormal occurrence of the water-bloom, wherein the liquid to be treated in which the water-bloom has been generated is treated by a biodegradation method, contact treatment with a magnesium ion supplying agent, and ultraviolet rays Treatment method characterized by combined use of irradiation treatment, magnesium ion supply tank for contacting water in water area where water-bloom is generated with magnesium ion supply agent, biodegradation treatment device for performing biological treatment, and ultraviolet light The present invention relates to a device which is equipped with an irradiation device and which suppresses the removal of water-bloom in water bodies and the occurrence of abnormalities. Further, in the apparatus of the present invention, any of the contact treatment with the magnesium ion supplying agent, the biodegradation treatment, and the ultraviolet irradiation treatment does not cause any problem, and the treatment may be performed simultaneously. .

The biodegradation method is not limited to any method, and any method such as an aerobic method or an anaerobic method may be used as long as it can convert organic phosphorus into inorganic phosphorus by utilizing a microorganism. Further, the biodegradation treatment device may be an existing device or a simple receiving tank to which a filler is added. The water-bloom and the organic phosphorus in the liquid to be treated are, for example, passed through a biological treatment tank using aerobic microorganisms, so that the food chain of bacteria, protozoa and metazoan in the treatment tank causes predation, metabolism or decomposition action. As a result, it is finally possible to decompose the inorganic phosphorus.

The magnesium ion supplying agent is necessary for the purpose of reacting with inorganic phosphorus dissolved in water to produce a sparingly soluble magnesium phosphate compound. Therefore, the magnesium ion supplying agent may be in any form of liquid, solid or slurry as long as it can supply magnesium ions. Examples of the liquid supply agent here include magnesium salt solutions such as magnesium chloride solution, magnesium sulfate solution, and magnesium nitrate solution, and solid examples include magnesium oxide, magnesium hydroxide, magnesium carbonate, and the like. Soil-based powder and granules can be mentioned. Examples of the slurry form include slurries composed of one or more of the above compounds. However, in order to maintain the magnesium ion supply effect for a long period of time, it is most preferable to use one or two or more materials of the magnesia-based powder or granular material. When a magnesium salt solution such as magnesium chloride or magnesium sulfate magnesium nitrate is used, the pH is temporarily lowered, and therefore it is necessary to add it while observing the influence on other coexisting organisms.

For the purpose of producing an inorganic phosphate ion and a sparingly soluble phosphate compound, the reason why the magnesia system is adopted instead of the lime system is that the pH which varies due to dissolution is smaller in the magnesia system. In addition, it is easy to operate within the pH of environmental water, and its reactivity with carbonate ions is low,
The reactivity with inorganic phosphorus does not deteriorate due to the formation of carbonic acid compounds, and the solubility is low compared to lime-based compounds,
This is because the reactivity continues for a long period of time, and the solubility of the sparingly soluble phosphate compound generated in the pH range of the environmental water is lower in the magnesia system, and the adsorption efficiency of dissolved phosphorus is higher.

[0013] Ultraviolet irradiation is carried out mainly for the purpose of removing the water-bloom in the lake where the abnormality has occurred in a short time. The algal killing of water-bloom in the liquid to be treated, which has already generated water-bloom, is performed with ultraviolet rays to accelerate the decomposition of water-bloom. The organic phosphorus in the decomposed water-bloom is decomposed into inorganic phosphorus by being processed in the biological treatment tank as described above. The cost problem, which is a major demerit of blue-green algae removal by ultraviolet irradiation, can be obtained by irradiation in a short time by using the biological treatment method and contact with a magnesium ion supplying agent in combination. When used for the purpose of suppressing the abnormal occurrence of water-bloom, it is possible to improve the effect in a short period of time with minimal equipment, especially during the season when eutrophication of lakes and marshes is expected. .

The inorganic phosphorus in the liquid to be treated that has passed through the biological treatment tank reacts with the magnesium ions supplied from the magnesium ion supplying agent to form a sparingly soluble magnesium phosphate compound, and as a result, the inorganic phosphorus. Can be fixedly removed.

As described above, the water in the water area in which the water-bloom is generated is biodegraded, magnesium ions are supplied,
We devised a treatment device from the technology of decomposing water-bloom by treating it with UV irradiation and fixing inorganic phosphorus in water as a sparingly soluble magnesium phosphate compound. As a result, it has become possible to cut off the supply of phosphorus to the environment that causes the abnormal development of the water-bloom and suppress the removal of the water-bloom and the abnormal development.

[0016]

【Example】

Example 1 Surface area in which water-bloom has already been generated 6.6 m ² , water depth 0.7
the water tank of m, and the colored carp ornamental put the water of 3m ³ were housed 8 animals purse. Next, a biodegradation treatment tank was installed as shown in FIG. The tank was made by processing a vinyl chloride cylinder having a diameter of 50 cm, and was filled with a total volume of the filler filling portion of 200 l so as not to hinder the passage of water through a commercially available vinyl chloride filler. A biofilm was formed on the surface of the filler and used. Two commercially available 15 W ultraviolet lamps were installed on the biodegradation treatment tank. The magnesium ion supply tank was attached to the outside of the water tank, and 2 kg of magnesium hydroxide was charged into the tank as a magnesium ion supply agent. The water to be treated that passed through the magnesium ion supply tank was pumped to the biodegradation treatment tank installed in the breeding aquarium, and circulation was started in the water tank → magnesium ion supply tank → biodegradation treatment tank → water tank. The transparency of the breeding water in the breeding aquarium when the circulation was started was 1.8 cm. The transfer capacity of the pump was set so that the total amount of water in the water tank could be transferred twice a day. The feed was administered once a day at a rate of 60 g each for breeding. On the second day after starting the operation of the pump and the ultraviolet lamp, Nishikigoi kept in the tank could be visually confirmed. On the 4th day after the start of the experiment, the turbidity, transparency, and inorganic phosphorus concentration of the breeding water in the breeding tank were 0.0 Klett-unit, 100 cm or more, respectively.
It was undetectable. The water in the water tank on the 4th day was transparent, and the effects of removing water-bloom and suppressing the occurrence of abnormalities were confirmed.

Example 2 A surface area of 80 m ² on which water-bloom has already been generated and a water storage amount of 150
60 Nishikigoi for appreciation were bred in an m ³ aquarium. next,
An iron tank (8.5 × 2 × 2 m) in which a biodegradation treatment tank having the shape shown in FIG. 2 and a magnesium ion supply tank were integrated was installed on the breeding water tank side. Biodegradation treatment tank (effective volume 16
The inside of m ³ ) was partitioned by a vinyl chloride plate in the water flow direction, and 8 m ³ of a commercially available vinyl chloride mesh filler was filled so as not to hinder water flow.
A biofilm was formed on the surface of the filler and used. Ten commercially available 100 W ultraviolet lamps were installed on the biodegradation treatment tank. The magnesium ion supply tank was placed at the drainage port of the biodegradation treatment tank, and 20 kg of magnesium hydroxide was added as a magnesium ion supply agent into the tank. The water in the breeding aquarium is sent to the biodegradation treatment tank by an underwater pump, and the water to be treated that has passed through the magnesium ion supply tank is directly returned to the breeding aquarium, and the water tank → biodegradation treatment tank → magnesium ion supply tank → water tank The circulation started. The transparency of the breeding water in the breeding aquarium when the circulation was started was 2.2 cm. The transfer capacity of the pump was set once a day so that the total amount of water in the water tank could be transferred. A total of 1 kg of food was fed twice a day for breeding.
On the 3rd day after starting the operation of the pump and the ultraviolet lamp, the Nishikigoi kept at the bottom of the tank could be visually confirmed. On the 7th day after the start of the experiment, the turbidity, the transparency, and the concentration of inorganic phosphorus of 0.0Klett-unit, 100 cm or more, respectively, were undetectable.
Met. The water in the aquarium on the 7th day was transparent, and the effects of removing water-bloom and suppressing the occurrence of abnormalities were confirmed.

Comparative Example 1 After the effects of removing water-bloom and suppressing the occurrence of abnormalities were confirmed in the test of Example 1, the irradiation of ultraviolet rays with an ultraviolet lamp was stopped and only the passage of water through the biodegradation treatment tank and the magnesium ion supply tank. Observation of the aquarium under conditions was continued. From the fifth day after the start of the experiment, it was visually confirmed that the water in the breeding aquarium turned slightly green. On the 10th day after the start of the experiment, the observation was started, and the breeding water in the breeding aquarium whose color became dark was collected and the turbidity, the transparency and the inorganic phosphorus concentration were measured.
The nit was 34.8 cm and 1.6 ppm. From this, it was confirmed that the effect of using UV irradiation in addition to biodegradation and supply of magnesium ions was used to remove the blue-green algae in the environmental waters with a large biological load and to suppress the abnormal occurrence.

Comparative Example 2 Among the tests of Example 1, the same test was carried out under the condition that the irradiation of the ultraviolet rays from the ultraviolet lamp was stopped and only the water was passed through the biodegradation treatment tank and the magnesium ion supply tank. In the same manner as in Example 1, the turbidity, the transparency, and the inorganic phosphorus concentration of the breeding water on the 4th day after the start of the experiment were measured and found to be 21.0 Klett-unit, 7.8.
It was cm and 5.9 ppm. As compared with Example 1, it was confirmed that the effect of Example 1 on the removal of blue-green algae in the water to be treated and the suppression of the occurrence of abnormalities by the irradiation of ultraviolet rays.

Comparative Example 3 Among the tests of Example 1, the same applies only under the conditions that the irradiation of ultraviolet rays by an ultraviolet lamp and the supply of magnesium ions in the magnesium ion supply tank are stopped and water is passed to the biodegradation treatment tank and air is aerated. Was tested. In the same manner as in Example 1, the turbidity, the transparency, and the inorganic phosphorus concentration on the fourth day after the start of the experiment were measured and found to be 30.2 Klett-unit, 1.8 cm, 6.8 ppm. As compared with Example 1, it was confirmed that the effect of Example 1 on removing blue-green algae and suppressing the occurrence of abnormalities by ultraviolet irradiation and contact with magnesium ions was confirmed.

[0021]

EFFECTS OF THE INVENTION As described above, conventional methods cannot be used by combining algae-killing with ultraviolet rays, decomposition of organic phosphorus by biological treatment, and fixation of inorganic phosphorus by contact treatment with a magnesium ion donor. It was possible to remove organic and inorganic phosphorus in water, which was a nutrient source for water-bloom, simultaneously from water, and as a result, it was possible to remove water-bloom and suppress abnormal occurrence. The present invention is a simple method by integrating the existing technologies, but by incorporating continuously the steps with their respective features, the equipment does not need the conventional large and expensive equipment, and special technology and equipment are not required. It is easy to design, produce and operate without having to use, is safer for the environment without using special chemicals to utilize the purification power in nature, and has a low running cost. Is a means of having.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a processing apparatus used in Example 1 of the present invention.

FIG. 2 is a schematic diagram of a processing apparatus used in Example 2 of the present invention.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical indication C02F 1/58 C02F 1/58 R

Claims (3)

[Claims] 1. A method for removing water-bloom in a water area and suppressing its abnormal occurrence, which is a combination of a treatment method in which water in the water area in which water-bloom is generated is brought into contact with a magnesium ion supplier, a biological treatment method, and an ultraviolet irradiation method. A method of suppressing the occurrence of water-bloom in water bodies and suppressing the abnormal occurrence thereof. 2. The blue-green alga in the water body according to claim 1, wherein the supplying agent capable of supplying magnesium ions at least in the water body is composed of one or more types of magnesia-based powder or granules. A method for removing and suppressing the occurrence of abnormalities. 3. A magnesium ion supply tank for contacting the water in the water area where the water-bloom is generated with a magnesium ion supply agent, a biodegradation processing apparatus for performing biological treatment, and an ultraviolet irradiation apparatus. A device that controls the removal of water-bloom in water bodies and its abnormal occurrence.