JP2020099846A - Water quality purification method - Google Patents

Abstract

To provide a water quality purification apparatus and a water quality purification method capable of effectively suppressing generation of microcystis by killing and removing microcystis and decreasing concentrations of nitrogen, phosphorus, and chlorophyll a in water by addition of flocculants together with UV radiation.SOLUTION: A water quality purification apparatus includes: intake means for intake of blue green algae-containing water containing microcystis (blue green algae, etc.); flocculant blending means for blending flocculants with water containing blue green algae and stirring; and UV radiation means for radiation of UV ray under convection current of water containing blue green algae. The flocculant blending means and the UV radiation means can be integrated together to constitute single means. Moreover, flocculants can be at least one of flocculants selected from aluminum sulfate, polyaluminum chloride, ferrous sulfate, ferric sulfate, ferric chloride, polychlorinated iron, and polymer flocculant, and a wavelength of the UV ray can be adjusted to 200-280 nm.SELECTED DRAWING: Figure 1

Description

The present invention relates to a water purification device and a water purification method for removing cyanobacteria in a water area (lake, etc.) to be purified.

When a large amount of nutrients such as nitrogen and phosphorus flow into lakes and marshes, cyanobacteria (hereinafter referred to as blue-green algae) are proliferated in large quantities using the nutrients. As a cause of eutrophication, which is a phenomenon in which nutrients such as nitrogen and phosphorus become excessive due to excessive growth of blue-green algae, sewage derived from point sources such as living and industrial areas and surface sources from agricultural areas through rivers. , Inflow of sediment, artificial activities around lakes, decomposition of fish, etc., elution from bottom mud. When a large amount of water-bloom grows, dissolved oxygen in the water becomes insufficient, fish and algae die, and the water environment deteriorates. Furthermore, the deterioration of natural environment and aquaculture environment, such as the generation of foul odor, the generation of gas such as hydrogen sulfide, and the pollution of water, and the deterioration of the landscape have become problems. Therefore, prevention of water quality deterioration in lakes and marshes due to the occurrence of water-bloom has become an urgent issue.

Conventionally, as a technology for suppressing the growth of blue-green algae, or a technology for removing them, a pumping filtration method (a method of pumping lake water, filtering the blue-green algae to return the water, dewatering the blue-green algae and disposing of it), using a water wheel or a submersible pump, etc. Various techniques have been developed, such as a method of stirring algae, a method of using an algicidal agent such as copper sulfate, an ultraviolet ray irradiation method of irradiating algae with ultraviolet rays to kill algae, and a deep aeration method.

For example, in Patent Document 1, as a method for removing the water-bloom in the water area and suppressing its abnormal occurrence, a treatment method in which water in the water area in which the water-bloom is generated is brought into contact with a magnesium ion supplying agent, a biological treatment method, and an ultraviolet irradiation method. A method of combining is disclosed. According to the present invention, it is possible to rapidly remove water-soluble organic phosphorus and inorganic phosphorus from water, which is a nutrient source for water-bloom, as a result, and to suppress the removal and abnormal occurrence of water-bloom. There is. Further, Patent Document 2 discloses a method for purifying water quality by causing a suspended substance in water in a water area to be purified to coagulate and settle using a coagulant and send a coagulant mixed liquid as a swirl flow. .. According to the present invention, it is said that suspended solids in water can be effectively removed by precipitation, the transparency of water bodies can be improved, and the malodor can be prevented.

JP-A-8-257591 JP, 2016-78021, A

In the method for purifying water-bloom disclosed in Patent Document 1, a magnesium ion-supplying agent is added to water containing water-blowing to irradiate with ultraviolet rays. Since three types of methods are used in combination, the processing apparatus becomes complicated, and it takes time and effort to manufacture and maintain. Therefore, a practical method that has a simple structure, low cost, and immediate effect is required.

The purification method of Patent Document 2 is a method of coagulating and precipitating water-bloom using a flocculant, but in order to remove the water-bloom, measures to prevent eutrophication of lakes and the like in order to suppress the generation of water-bloom. In particular, it is necessary to take fundamental measures to reduce the concentrations of causative substances such as nitrogen, phosphorus and chlorophyll a. Therefore, a method for preventing eutrophication of lakes and marshes at the same time as removing water-bloom is desired.

In view of the above-mentioned problems, the present invention effectively removes algal blooms by algae removal by irradiating ultraviolet rays together with addition of a flocculant, and lowers the concentrations of nitrogen, phosphorus, and chlorophyll a in water to effectively generate algal blooms. An object of the present invention is to provide a water purification apparatus and a water purification method that suppress the above.

In order to achieve the above-mentioned object, the invention according to claim 1 is a water purification apparatus for purifying water quality by removing cyanobacteria, and water intake means for taking in cyanobacteria-containing water containing cyanobacteria, It is characterized by comprising a coagulant mixing means for mixing and stirring the cyanobacteria-containing water with a coagulant, and an ultraviolet irradiation means for irradiating ultraviolet rays while convection of the cyanobacteria-containing water.
The invention described in claim 2 is the water purification apparatus according to claim 1, wherein the coagulant mixing means and the ultraviolet irradiation means are combined into one means.
The invention according to claim 3 is the water purification apparatus according to claim 1 or 2, wherein the coagulant is aluminum sulfate, polyaluminum chloride, ferrous sulfate, ferric sulfate, ferric chloride. , At least one or more coagulant selected from polyiron chloride and polymer coagulant.
A fourth aspect of the present invention is the water purification apparatus according to any of the first to third aspects, wherein the wavelength of the ultraviolet rays is 200 to 280 nm.
The invention according to claim 5 is the water purification apparatus according to any one of claims 1 to 4,
The water purification device is in the form of a boat that operates in a water area to be purified.
The invention according to claim 6 is a water purification method for purifying water quality by removing cyanobacteria, wherein a step of taking in cyanobacteria-containing water and mixing and stirring the cyanobacteria-containing water with a flocculant. It is characterized by including a step and a step of irradiating with ultraviolet rays while convection of the cyanobacteria-containing water.
The invention according to claim 7 is the water purification method according to claim 6, wherein a step of mixing the cyanobacteria-containing water with a coagulant and stirring the mixture, and a step of convection of the cyanobacteria-containing water with ultraviolet rays. It is characterized in that the irradiation step is performed at the same time.

According to the water purification apparatus and the water purification method of the present invention, by adding an aggregating agent and irradiating with ultraviolet rays, algae are removed by algae removal, and the concentration of nitrogen, phosphorus, and chlorophyll a in the water is reduced to remove algae. The generation can be effectively suppressed.

It is a schematic diagram showing the whole composition of the water purification device which is one example of the present invention. It is a plane explanatory view of one ultraviolet irradiation tank of the water purification apparatus shown in FIG. It is explanatory drawing which shows the flow of the water purification method which is one Example of this invention. It is explanatory drawing which shows the water purification apparatus of the ship form which is one Example of this invention, (A) is a top view, (B) is a perspective view. It is a graph which shows the relationship between a hydrogen ion index (pH) and treated water (including raw water). It is a graph which shows the relationship between a hydrogen ion index (pH) and ultraviolet irradiation time. 3 is a graph showing the relationship between the concentration of chlorophyll a and treated water (including raw water). 3 is a graph showing the relationship between the concentration of chlorophyll a and the ultraviolet irradiation time. 6 is a graph showing the relationship between the concentration of soluble phosphorus and treated water (including raw water). It is a graph which shows the relationship between the density|concentration of soluble phosphorus, and ultraviolet irradiation time. 6 is a graph showing the relationship between the concentration of soluble nitrogen and treated water (including raw water). It is a graph which shows the relationship between the density|concentration of soluble nitrogen, and ultraviolet irradiation time.

Embodiments of the present invention will be described below with reference to the drawings. In the following figures, common parts are designated by the same reference numerals, and duplicate description of the same reference numerals is omitted. In the following examples, an example in which the water purification device and the purification method are used for blue-green algae in lakes and marshes is described, but the water purification device and the purification method of the present invention are not limited to lake purification treatments, but also to reservoirs and moats. It can also be applied to the purification treatment of water in rivers and other water areas to be purified and in water tanks. Further, in the examples, cyanobacteria, particularly blue-green algae, will be described as an example, but the present invention can also be applied to other algae (green algae, diatoms, dinoflagellates, etc.).

[Water purification device and water purification method]
First, the structure and method of the water purification device 1 of this embodiment will be described with reference to FIGS. 1 to 4. 1 is a schematic diagram showing the overall configuration of the water purification device 1, FIG. 2 is a plan view of one ultraviolet irradiation tank of the water purification device shown in FIG. 1, and FIG. 3 shows a water purification method. It is explanatory drawing which shows a flow. 4A and 4B are explanatory views showing the boat-shaped water purification device 1, where FIG. 4A is a plan view and FIG. 4B is a perspective view. The water purification device 1 of the present embodiment is a device used in a limited water area of a lake and marsh, and is a device provided with a function of aggregating water-bloom with a coagulant and precipitating, and a function of algae killing water-bloom by ultraviolet irradiation. is there.

As shown in FIG. 1, the water purification apparatus 1 includes a water intake means for taking in water containing water-bloom (hereinafter referred to as water-containing water), and a coagulant mixing means for mixing the water taken in with a coagulant and stirring the mixture. 20 (hereinafter, referred to as a flocculant mixing tank) and ultraviolet irradiation means 40 (hereinafter, referred to as an ultraviolet irradiation tank) for irradiating ultraviolet rays while convection the water containing the water-bloom are basic components. The water purification device 1 further passed through a water storage tank 10 for storing the taken water, a tank 30 for storing a coagulant (hereinafter referred to as a coagulant storage tank), a coagulant mixing means 20, and an ultraviolet irradiation means 40. A recovery tank 50 for recovering later water and a settling tank 70 for storing the precipitate may be provided. In the present embodiment, a water purification device 1 including them will be described.

The water intake means is a means for taking in water-containing water from the water of a lake and marshes, and includes a pipe (hose) 12 and a pump 11 for taking water. In the water purification method of the present embodiment shown in FIG. 3, first, the water-bloom-containing water is taken in by this water intake means (step 1, hereinafter referred to as S1 and the like). The base end of the pipe 12 is connected to the water storage tank 10 (or the flocculant mixing tank 20), and the water-containing water is pumped up by the drive of the pump 11 in a state where the tip is arranged in the lake. The pump 11 may be manual or automatic as long as it can pump up the required amount of water. The pipe 12 is provided with an on-off valve, which opens when absorbing the water containing water-bloom and closes after absorbing the water. A turbidimeter (not shown) may be installed near the pump 11. By installing a turbidimeter, the concentration of water-bloom can be predicted, and the amount of suction water can be manually changed (or automatically controlled) according to the concentration. As a result, it is possible to absorb a required amount of water-containing water of a suitable concentration of blue-green algae, and it is possible to efficiently perform the ultraviolet irradiation described below. The diameter of the pipe 12 for water intake needs to be at least about 3 cm so that the water containing the water-bloom will not be stagnant and water can be taken in a wide range. The number of the pipe 12 and the pump 11 is not limited to one and may be plural.

The water taken in is stored in the water storage tank 10 and is supplied to the coagulant mixing tank 20 in a necessary amount. Although the water may not be stored in the water storage tank 10 and may be directly supplied to the coagulant mixing tank 20, the provision of the water storage tank 10 allows the coagulant mixing tank 20 to be stably supplied with a predetermined amount of water. The water stored in the water storage tank 10 is supplied to the flocculant mixing tank 20 in a predetermined amount through the pipe by driving the pump 14. The pipe is provided with an on-off valve 15, which is opened when water is supplied to the coagulant mixing tank 20 and is closed after the water supply is completed.

In the coagulant mixing tank 20, the water supplied from the water storage tank 10 (or the water intake means 11) and the coagulant are mixed and stirred (S2 in FIG. 3). The required amount of the coagulant is supplied from the coagulant storage tank 30 to the coagulant mixing tank 20 through the pipe by driving the pump 31. The pipe is provided with an on-off valve 32, which is opened when the coagulant mixing tank 20 is supplied, and is closed after the supply is completed. The coagulant storage tank 30 is not an indispensable component of the present invention and may be configured to directly supply a predetermined amount of the coagulant to the coagulant mixing tank 20. It is possible to stably supply a predetermined amount of the coagulant to the tank 20.

It should be noted that the coagulant storage tank 30 is not limited to one, and may be plural depending on the type of coagulant. As the aggregating agent, at least one aggregating agent selected from aluminum sulfate, polyaluminum chloride, ferrous sulfate, ferric sulfate, ferric chloride, polyiron chloride, and polymer aggregating agent is used. In this embodiment, aluminum sulfate and polyaluminum chloride are used in particular. By using such an aggregating agent, the water-bloom can be aggregated and precipitated. Further, as described in the experimental results described later, the concentrations of nitrogen, phosphorus and chlorophyll a in water can be lowered.

In order to exert the effect of the coagulant, rapid stirring/slow stirring is required after adding the coagulant to the water supplied from the water storage tank 10. Rapid stirring is a reaction necessary with a flocculant, and slow stirring is an operation necessary for promoting floc (aggregate) formation. Therefore, in order to effectively mix and stir the coagulant, the coagulant mixing tank 20 is provided with a blower (centrifugal fan) 21 that strongly supplies air and a diffuser 22 that efficiently diffuses the water flow. You can The means for mixing and stirring the coagulant is not limited to these, and other means such as a convection plate or a vibration device may be used. In the present system, the function of the slow-speed stirring can also be achieved without any special slow-speed stirring, whereby the gentle stirring naturally occurs after the discharge and the precipitation function can be achieved.

The water-containing water that has been mixed and stirred in the coagulant mixing tank 20 is supplied from the coagulant mixing tank 20 by a necessary amount to the ultraviolet irradiation tank 40 through the pipe by driving the pump 23. The pipe is provided with an on-off valve 24, which is opened when the ultraviolet irradiation tank 40 is supplied and closed after the supply is completed. The ultraviolet irradiation tank 40 may be one, but may be plural. In this embodiment, three ultraviolet irradiation tanks 40 are used as shown in FIG. Each of the three ultraviolet irradiation tanks 40 is connected by a pipe, and a pump 41 and an opening/closing valve 42 supply a predetermined amount of water treated in each ultraviolet irradiation tank 40.

The ultraviolet irradiation tank 40 is preferably a closed tank that is shielded by a material having a light shielding property so that light other than the ultraviolet lamp 43 does not enter. The ultraviolet irradiation tank 40 is composed of a plurality of convection plates 44 for convection the water-containing water and a plurality of ultraviolet lamps 43. Further, a magnetic processor 45 (magnet ring) may be further provided in the pipe at the entrance of the ultraviolet irradiation tank 40. The magnetic processor 45 is composed of permanent magnets arranged on the outer circumference of the pipe so that the magnets facing each other with the pipe interposed therebetween have different polarities. A pair of permanent magnets (N pole and S pole) may be used, but a plurality of permanent magnets are preferable. With this configuration, even if the metal powder is mixed with the water passing through the pipe, it can be effectively removed.

The ultraviolet lamp 43 does not directly enter the water containing the water-bloom, but puts a quartz glass tube (not shown) through which ultraviolet rays pass into the ultraviolet irradiation tank 40, and puts the ultraviolet lamp 43 therein to irradiate ultraviolet rays. It is preferable that In the case of ordinary glass, visible light and near-infrared rays are transmitted, and ultraviolet rays are absorbed, but in the case of quartz glass, ultraviolet rays are transmitted, so in this embodiment, a quartz glass tube is used. Thereby, the light of the ultraviolet lamp 43 can be irradiated to the water-containing water, and the ultraviolet lamp 43 can be prevented from being contaminated with the water containing water and the durability can be improved.

The shape and size of the ultraviolet ray irradiation tank 40 are not particularly limited, but it is preferable that the ultraviolet ray irradiation tank 40 is configured in such a shape and size that the water containing the blue-green algae is sufficiently exposed to the light of the ultraviolet lamp 43. The size of one ultraviolet irradiation tank 40 may be, for example, cylindrical and has a diameter of 400 to 500 mm, and the diameter portion thereof has a longitudinal length of 1000 to 2000 mm. As the ultraviolet lamp 43, a lamp having a strong bactericidal action with a wavelength of 200 to 280 nm and capable of irradiating ultraviolet rays (UV-C) that causes cell destruction is used. In particular, it is preferable to irradiate with ultraviolet rays having a wavelength of about 270 nm that matches the absorption wavelength of DNA of cells such as algae. In this embodiment, irradiation is performed at a wavelength of 253.7 nm (203W).

A plurality of (for example, 2 to 7) ultraviolet lamps 43 may be installed in one ultraviolet irradiation tank 40 in order to make the light from the ultraviolet lamps 43 illuminate the water containing water as much as possible, or have a large surface area. A plurality of U-shaped ultraviolet lamps 43 may be used. In this embodiment, three ultraviolet lamps 43 are installed. Further, as shown in FIGS. 1 and 2, a plurality of convection plates 44 are provided inside the ultraviolet irradiation tank 40 so that the water containing blue-green algae convection. The convection plate 44 is configured by twisting one flat plate, for example. In FIG. 1, the plurality of convection plates 44 are described as being vertically arranged in the side direction of the ultraviolet lamp 43, but actually, the plan view of the ultraviolet irradiation tank 40 in FIG. As shown in the figure, a convection plate 44 is arranged on the side surface in the direction in which the water-containing water flows. In FIG. 2, the arrow indicates the direction in which the water containing water-bloom convects at the convection 44 plate. After the water containing the water-bloom is supplied by the pump 23, it flows in the lateral direction of the ultraviolet irradiation tank 40, but when it hits the concavo-convex portion of the convection plate 44, it flows vertically (convection) to the left and right of the ultraviolet lamp 43 repeatedly. It will be exposed to ultraviolet rays. In this way, ultraviolet rays are radiated for a certain period of time while the water containing water-bloom is convected in the ultraviolet ray irradiation tank 40 (S3 in FIG. 3). As a result, the water containing the water-bloom can be sufficiently exposed to the ultraviolet rays of the ultraviolet lamp 43, and the water-bloom can be killed.

The water-containing water that has been irradiated with ultraviolet rays (for example, for 1 minute) in the first (first) ultraviolet irradiation tank 40 is pumped up by the drive of the pump 41 and supplied to the next ultraviolet irradiation tank 40. By driving the pump 41, the water-bloom-containing water can be vigorously convected in the second ultraviolet irradiation tank 40 and the ultraviolet irradiation can be performed (for example, for 1 minute). Further, by irradiating ultraviolet rays in the third ultraviolet irradiation tank 40 (for example, for 1 minute) and repeatedly applying the water-bloom-containing water sufficiently to the ultraviolet rays of the ultraviolet lamp 43, the algal blooms can be killed. The blue-green water containing water that has been subjected to the ultraviolet ray treatment in the third ultraviolet ray irradiation tank 40 is supplied or discharged to the recovery tank 50 by the pump 41 and the on-off valve 42 of the pipe (S4 in FIG. 3).

Although three ultraviolet irradiation tanks 40 are used in this embodiment, it is not necessary to pass the three ultraviolet irradiation tanks 40. For example, when the density of the water-bloom is low, it may be sufficient to perform the UV treatment only with the first UV irradiation tank 40. In that case, the water-containing water containing the UV treated with the first UV irradiation tank 40 may be sufficient. Is supplied or discharged to the recovery tank 50 by the pump 41 and the on-off valve 42 of the pipe. Further, depending on the density of the blue-green algae, it may be considered that the first and second ultraviolet irradiation tanks 40 only perform the ultraviolet treatment.

The control device (control panel) 60 controls the ultraviolet lamp 43, the pump 41, the opening/closing valve 42, and the like described above. In particular, it is possible to control so that the irradiation time and wavelength of ultraviolet rays are changed and the power is turned on and off automatically. For example, automatic control may be performed such that the blue-water containing water enters the ultraviolet irradiation tank 40 and is sealed and then the power of the ultraviolet lamp 43 is turned on, and after the water is discharged from the ultraviolet irradiation tank 40, the power is turned off. .. Further, the pump 41 and the opening/closing valve 42 of the ultraviolet irradiation tank 40 may be controlled so that a predetermined amount of water-containing water can be supplied to and discharged from the ultraviolet irradiation tank 40. Further, the control device 60 may use not only the ultraviolet lamp 43 but also a turbidimeter installed in the vicinity of the above-mentioned water intake means to automatically control the amount of suction water according to the concentration of water-bloom (not shown). .. Further, the water storage tank 10, the coagulant mixing tank 20, the pump and the opening/closing valve of the coagulant storage tank 30 may be automatically controlled, and the blowing blower 21 that promotes mixing and stirring of the coagulant storage tank 30 may be automatically controlled ( (Not shown).

Although the ultraviolet irradiation tank 40 is installed after the coagulant mixing tank 20 in this embodiment, the coagulant mixing tank 20 may be installed after the ultraviolet irradiation tank 40. In that case, a step (S3) of irradiating with ultraviolet rays is performed before the step (S2) of mixing and stirring the coagulant with the water-containing water. In addition, although the coagulant mixing tank 20 and the ultraviolet irradiation tank 40 are separately configured in this embodiment, the coagulant mixing tank 20 and the ultraviolet irradiation tank 40 may be integrated into one tank. In that case, by supplying the coagulant directly to the ultraviolet irradiation tank 40, the step of mixing and stirring the coagulant (S2) and the step of irradiating the ultraviolet ray (S3) can be simultaneously performed. Here, the meaning of "simultaneous" does not mean completely "simultaneous", but also includes the case where the step of mixing and stirring the flocculant is several seconds earlier or later (hereinafter, "simultaneous"). "Is also used interchangeably). As described above, since the ultraviolet irradiation tank 40 is provided with the convection plate 44, a turbulent flow is generated with the irradiation of ultraviolet rays, and the coagulant is sufficiently mixed. However, a blast blower 21 or the like is further provided to promote stirring. May be By coagulating the flocculant mixing tank 20 and the ultraviolet irradiation tank 40 into one tank, the water-bloom can be agglutinated and precipitated, the water-bloom can be killed, and the water containing cyanobacteria can be efficiently purified.

The recovery tank 50 temporarily stores the treated water treated by the ultraviolet irradiation tank 40. The recovery tank 50 is not an indispensable component of the present invention, and it is possible to directly discharge the treated water after the irradiation of ultraviolet rays without the recovery tank 50. When the recovery tank 50 is provided, it is preferable that the recovery tank 50 is provided in plural instead of one in order to constantly store the treated water treated in the ultraviolet irradiation tank 40. The treated water in the recovery tank 50 is separated into a settling layer in which the algae that have been killed algae settle, and a supernatant layer that becomes transparent water (purified water). In order to obtain purified water of higher purity, the recovery tank 50 is preferably equipped with a filter (not shown). The filter is not an essential component of the present invention, and the recovery tank 50 may not have a filter. When a filter is provided, the purified water obtained by filtering with the filter is pumped up by the pump 51, the on-off valve 52 is opened, and discharged through the discharge pipe into the lake. Further, the sediment remaining on the filter is transferred to the sedimentation tank 70 through the pipe through the opening/closing valve 71 and collected. The settling tank 70 may be provided in the recovery tank 50. If the recovery tank 50 is not equipped with a filter, the purified water of the supernatant is pumped up by the pump 51 and discharged into the lake, and the remaining precipitate can be discharged as it is or transferred to the precipitation tank 70 for recovery. ..

As described above, the water purification apparatus is configured, and the series of steps of the water purification method is completed (FIG. 3). By repeating this series of steps, it is possible to purify the water quality of the purification target water area of the lake. The present embodiment is an example, and the present invention is not limited to this configuration and method. For example, in the present embodiment, each of the tanks 10 to 50 supplies a predetermined amount to the next tank by using the on-off valve and the pump provided in the pipe, but only the on-off valve is provided without using the pump. Then, a step may be provided in each tank, and a predetermined amount may be supplied by the height difference (gravitational force of water).

The water purification device described above can be installed on the ground or on the water, but when installed on the water, for example, it can be configured in a boat shape. FIG. 4 is an explanatory view showing a boat-shaped water purification device, (A) is a plan view and (B) is a perspective view. A large boat may be used when the water to be purified in the lake covers a wide area, but a small boat with good operability is used in this embodiment.

As shown in the plan view of FIG. 4(A), the water purification device 1 in the form of a boat includes a small boat 100, the above-mentioned water intake means, a water storage tank 10, a coagulant mixing tank 20, a coagulant storage tank 30, and an ultraviolet irradiation tank. 40, a recovery tank 50 (sedimentation tank 70), a control device 60, a drive device and the like are mounted. A pipe (hose) 12 and a pump 11 are used as water intake means of the boat-shaped water purification device 1. As shown in FIG. 4(A), the fixture (floating or weight) that fixes the tip of the pipe 12 in the lake so that the water-bloom in the lake can be suitably collected without the tip of the pipe 12 floating on the surface of the lake. ) 111 may be attached. The water-intake means pumps up the water-containing water by driving the pump 11, and supplies it to the water storage tank 10. As described above, a turbidimeter may be installed near the pump 11 to automatically control the amount of suction water according to the concentration of water-bloom (not shown). The water supplied to the water storage tank 10 is treated in the coagulant mixing tank 20, the ultraviolet irradiation tank 40, and the recovery tank 50 (precipitation tank 70).

As shown in the perspective view of FIG. 4B, a sail 101 may be attached to the small boat 100 to obtain a propulsive force by wind. The sail 101 is not an indispensable structure and may be operated only by an engine. However, by using a sail ship, it is possible to utilize the natural power, and because it does not look like a water-bloom recovery ship, it blends into the scenery of the lake. be able to.

Since the boat-shaped water purification device 1 can easily move to the water area where the water-bloom breeds, the water-containing water can be easily taken in compared to the water purification device 1 installed on the ground. In addition, since the flocculant mixing tank 20 and the ultraviolet irradiation tank 40 swing by operating the small boat 100, the water-containing water is agitated more efficiently and ultraviolet rays can be sufficiently applied.

Further, a GPS may be incorporated in the control device 60 to read a map of lakes and marshes and control the automatic driving based on the map. For automatic driving, it is necessary to have a camera, a sensor, etc. for storing map information and grasping surrounding conditions. Further, the control device 60 needs a program (software) capable of controlling the drive device of the small boat 100 based on the grasped information. When the ship-shaped water purification device 1 can be automatically operated, the labor of the worker can be reduced, and the water-bloom-containing water in the lake can be taken in and purified over a wide range.

[Experiment content and results]
Next, an experiment for verifying the effect of the method of the present invention will be described. The details of the experiment in which the coagulant was added to the water containing the water-bloom containing ultraviolet light and the results thereof will be described with reference to Table 1 below and FIGS. 5 to 12. Table 1 lists the water containing blue-green algae (raw water in Table 1 and Figures 5 to 12) collected from Senba Lake (Nakagawa river system in Mito City, Ibaraki Prefecture), which is a representative of eutrophic lakes ), and water that contains blue-green algae irradiated with ultraviolet rays (253.7 nm, 203 W, described as UV) for 1 to 3 minutes, and aluminum sulfate as a coagulant simultaneously with the ultraviolet rays (described as a band in Table 1 and FIGS. 5 to 12). According to the experimental results, polyaluminum chloride (described as PAC in Table 1 and FIGS. 5 to 12) was added at a 2 mol ratio or a 2.5 mol ratio, and only polyaluminum chloride (PAC) was added without irradiation with ultraviolet rays. is there. The resulting hydrogen ion index (pH), concentration of chlorophyll a (Chl-a) (μg/l), soluble phosphorus (dissolved state P) (mg/l) and soluble nitrogen (dissolved state N) in water Represents the concentration (mg/l) of. 5-12 are a summary of the results of Table 1 for ease of analysis.

In addition, the amount of the coagulant added in the present experiment was calculated on the assumption that the water-containing water containing the test sample contained 5 (mg/l) phosphorus, and the amount of the coagulant corresponding to each molar ratio was calculated. For example, when the water containing water-bloom is 100 ml, the mass of phosphorus contained is 0.5 (mg/l). The molar ratio in this experiment is not an exact molar ratio but an approximate molar ratio. For example, when an aluminum-based coagulant is added at a molar ratio of 2, the calculation is as follows.

In the above calculation formula, the atomic weight of Al was 26.98 g/mol and the atomic weight of P was 30.97 g/mol. When the molar ratio is 1, the above value becomes half. In addition, if the water containing blue-green algae is 500 ml, the addition amount will be 5 times. The additive solution used was a commercially available polyaluminum chloride (PAC) solution diluted 100 times (weigh the mass of the polyaluminum chloride solution with an electronic balance and use a graduated cylinder to make it ultra-pure to a concentration of 1/100). Diluted with water). A commercially available polyaluminum chloride solution has a specific gravity of about 1.2 at 20° C. and often has an aluminum oxide content of about 10%. Since the specific gravity was not completely determined, the volume of 20 kg of the polyaluminum chloride solution used this time was calculated to be 18 L. From the calculation results, it can be seen that the case where 1.5 ml of the above-mentioned diluted solution is added to 100 ml of water containing water-bloom corresponds to a molar ratio of 1. The slight increase in the total volume due to the addition of the diluent was ignored. Similar calculations were made for the amounts of other flocculants added.

As shown in Table 1, the water-containing water (No. 10) had a pH of 10.56, a chlorophyll a (Chl-a) concentration of 1500 (μg/l), and a soluble phosphorus concentration of 0.023 (mg). /L), the soluble nitrogen is 0.85 (mg/l), and the color of the water-bloom-containing water is cloudy in green as a whole. The treated waters of Nos. 1 to 3 were each irradiated with ultraviolet rays for 1 minute, 2 minutes, and 3 minutes while turbulently flowing the water-containing water. The treated waters of Nos. 4 to 6 and Nos. 7 to 9 were obtained by irradiating the water-containing water with ultraviolet rays for 1 to 3 minutes and adding aluminum sulfate (band) and polyaluminum chloride (PAC) at a molar ratio of 2.5, respectively. It was added and rapidly stirred (slowly stirred if necessary).

The treated water of No. 11 was obtained by adding aluminum chloride (PAC) at a 2 molar ratio without irradiating the water-containing water with ultraviolet rays and rapidly stirring (slowly stirring if necessary). Further, the treated water of Nos. 12 and 13 was irradiated with ultraviolet rays for 1 to 3 minutes, respectively, to the water-containing water, and polyaluminum chloride (PAC) was added at a molar ratio of 2 for rapid stirring (slow stirring if necessary. It was stirred).

First, each treated water was observed, and the appearance compared with the water-containing green water containing blue water (No. 10) will be described. In the treated waters of Nos. 1 to 3 (UV irradiation only), the longer the time of UV irradiation, the more decolorized the green color of the water-bloom (being killed by algae) becomes cloudy, and only part of the water-bloom (green) floats. It was Particularly, when the ultraviolet irradiation of No. 3 was performed for 3 minutes, it was possible to confirm the appearance of cloudiness as a whole, and the effect of ultraviolet irradiation became clear. However, although the decolorization decomposition of the water-bloom was carried out only by the ultraviolet rays, there was a case where it did not precipitate, and the result that it floated on the water surface was seen. When the concentration of the water-bloom is low, the water-bloom is decolorized and decomposed, and the floating problem is reduced, so that the coagulant may not be added in some cases.

Decolorization decomposition was confirmed in all of the treated waters of Nos. 4 to 6 (UV irradiation and aluminum sulfate), and the longer the irradiation time, the more decolorized the green color of water-bloom. It was also confirmed that the precipitation properties were extremely high. Therefore, by the irradiation of ultraviolet rays and the addition of aluminum sulfate (band), the result was that the water-bloom did not float but effectively precipitated.

As with the treated waters of Nos. 4 to 6, the treated waters of Nos. 7 to 9 and 12, 13 (ultraviolet irradiation and polyaluminum chloride) were all confirmed to be decolorized and decomposed, and it was also confirmed that the precipitation property was extremely high. .. Therefore, it was found that the blue-green algae did not float but was effectively precipitated by the irradiation of ultraviolet rays and the addition of polyaluminum chloride (PAC). Decolorization decomposition was also confirmed in the treated water of No. 11 (polyaluminum chloride only), and it was confirmed that precipitation occurred. However, since it is not irradiated with ultraviolet rays, the algae have not been killed by the algae, and it is possible that they will surface after a lapse of time.

Next, the hydrogen ion index (pH) of each treated water, the concentration of chlorophyll a, the concentration of soluble phosphorus, and the concentration of soluble nitrogen will be described. FIG. 5 is a graph showing the relationship between the hydrogen ion index (pH) and treated water (including raw water), and FIG. 6 is a graph showing the relationship between the hydrogen ion index (pH) and ultraviolet irradiation time. The hydrogen ion index (pH) is measured immediately after the treatment of the water-containing water and after 7 days from the treatment, and therefore both data are displayed. In FIG. 5, the data after 7 days are represented by arrows. Generally, the pH range suitable for the inhabitation of the organisms that compose the ecosystem is 5.8 to 8.5. If the pH range is outside this range, nutrients are less likely to be ingested by plants, the productivity of the organisms decreases, and Overall production is also expected to decline.

It can be seen from Table 1 and FIG. 5 that the pH after the main treatment changes to around neutral (6 to 8) after the main treatment, so that the ecosystem is not affected. Further, as shown in FIG. 6, the pH of the treated water to which aluminum sulfate (band) and polyaluminum chloride (PAC) were added at a high molar ratio (molar ratios 2 and 2.5) was drastically decreased 1 minute after the irradiation with ultraviolet rays. It was found that the treated water containing polyaluminum chloride (PAC) was neutralized. Aluminum sulphate (band) had a greater decrease in pH compared to polyaluminum chloride (PAC), which was not neutralized after 7 days. However, the pH of the treated water of aluminum sulfate (band) is considered to be neutralized by the dilution of natural water, and therefore it is considered that there is no problem in discharging it. It was also found that the treated water to which the coagulant was not added was neutralized after about 7 days.

FIG. 7 is a graph showing the relationship between the concentration of chlorophyll a and treated water (including raw water), and FIG. 8 is a graph showing the relationship between the concentration of chlorophyll a and ultraviolet irradiation time. As with the pH, the concentration of chlorophyll a is measured immediately after the treatment with the water-containing water and after 7 days from the treatment, so both data are displayed. In FIG. 7, the data after 7 days are represented by arrows. Incidentally, in the supernatant after the water-blowing was precipitated by the ultraviolet irradiation and the treatment with the coagulant, the concentration of chlorophyll a was below the detection limit, so the concentration of chlorophyll a was measured by thoroughly stirring the water-containing water after treatment. ing. In the graph showing the relationship between the concentration of chlorophyll a after 7 days and the ultraviolet irradiation time in Fig. 8(B), the value on the vertical axis (the concentration of chlorophyll a) overlaps in the graph of the uniform scale, and the state is difficult to understand. Therefore, the vertical axis is displayed on a logarithmic scale.

As shown in Table 1 and FIGS. 7 and 8, the concentration of chlorophyll a in the raw water is as high as 1500 (μg/l), but the concentration of chlorophyll a is remarkably reduced about 1 minute after irradiation with ultraviolet rays. This indicates that the blue-green cells were destroyed by UV irradiation. As shown in FIG. 8, it can be seen that the concentration of chlorophyll a decreases as the ultraviolet irradiation time increases to 2 minutes and 3 minutes. Further, it is found that the concentration of chlorophyll a is lower in the treated water to which aluminum sulfate (band) is added together with the irradiation of ultraviolet rays. Comparing the concentrations of chlorophyll a in aluminum sulfate (band) and polyaluminum chloride (PAC), the concentration of chlorophyll a was lower in aluminum sulfate (band). Therefore, it is found that aluminum sulfate (band) is more effective in removing chlorophyll a.

After 7 days, the concentration of chlorophyll a in the raw water increased to 1900 (μg/l), but the concentration of chlorophyll a in the UV-treated water decreased, and treatment with the addition of aluminum sulfate (band) The concentration of chlorophyll a in water was further reduced. Therefore, chlorophyll a was surely decomposed by ultraviolet irradiation and addition of aluminum sulfate (band). Further, the concentration of chlorophyll a in polyaluminum chloride (PAC) was further lowered after 7 days, and chlorophyll a could be removed by almost 95%. From the above results, it was found that the concentration of chlorophyll a was significantly decreased after 7 days, once the water-bloom cells were destroyed by the ultraviolet rays. It has been confirmed from the evaluation of changes over time that even after 1 minute of ultraviolet irradiation, the water-bloom cells are destroyed and damaged, and die after 2-3 days.

FIG. 9 is a graph showing the relationship between the concentration of soluble phosphorus and treated water (including raw water), and FIG. 10 is a graph showing the relationship between the concentration of soluble phosphorus and ultraviolet irradiation time. 10 is similar to the graph of FIG. 8(B), it is difficult to see how the values on the vertical axis (concentration of soluble phosphorus) overlap in the graph on the uniform scale, so the vertical axis is displayed on a logarithmic scale. There is. As shown in Table 1 and FIG. 9, the concentration of soluble phosphorus was increased by the irradiation of ultraviolet rays. This seems to be because the blue-green alga colony cells were destroyed by the UV irradiation, and the concentration of soluble phosphorus increased. However, the concentration of soluble phosphorus decreased extremely significantly by adding aluminum sulfate (band) and polyaluminum chloride (PAC). From FIG. 10, when the aluminum sulfate (band) was added, the concentration of soluble phosphorus increased slightly as the irradiation time of ultraviolet light became longer. Also in polyaluminum chloride (PAC), the concentration of soluble phosphorus increased slightly as the irradiation time with ultraviolet light increased. Comparing the soluble phosphorus concentrations of aluminum sulfate (band) and polyaluminum chloride (PAC), polyaluminum chloride (PAC) was lower. Therefore, it is understood that polyaluminum chloride (PAC) is effective for removing soluble phosphorus.

11 is a graph showing the relationship between the concentration of soluble nitrogen in Table 1 and treated water (including raw water), and FIG. 12 is a graph showing the relationship between the concentration of soluble nitrogen and ultraviolet irradiation time. .. As shown in Table 1 and FIG. 11, the concentration of soluble nitrogen was increased by the irradiation of ultraviolet rays. It is considered that the UV irradiation destroyed the water-bloom colony cells and increased the concentration of soluble nitrogen. However, the concentration of soluble nitrogen was lowered by adding aluminum sulfate (band) or polyaluminum chloride (PAC). From FIG. 12, the concentration of soluble nitrogen was hardly changed by the ultraviolet irradiation time when aluminum sulfate (band) was added, but in the case of polyaluminum chloride (PAC), the longer the ultraviolet irradiation time is, the smaller the concentration becomes. Increased. Comparing the concentrations of soluble nitrogen in aluminum sulfate (band) and polyaluminum chloride (PAC), polyaluminum chloride (PAC) was lower. Therefore, it is understood that polyaluminum chloride (PAC) is also effective for removing soluble nitrogen.

Further, the treated water of No. 11 was obtained by adding polyaluminum chloride (PAC) at a 2 molar ratio without irradiating the water containing blue water with ultraviolet rays, but as shown in Table 1, as compared with raw water, Dissolved phosphorus was reduced and maintained within the pH standard. Therefore, it was found that such a phosphorus removing effect can be obtained without irradiation of ultraviolet rays (compared with the treated water of No. 13). However, the concentration of chlorophyll a did not decrease much even after 7 days, and it was found that an immediate effect could not be obtained unless it was irradiated with ultraviolet rays. Therefore, in order to ensure the precipitation of water-bloom and to obtain an immediate effect of damaging and killing algal cells, a purification treatment in which both UV irradiation and addition of a coagulant are performed is preferable. It is preferable to carry out not only the ultraviolet irradiation or the coagulant, but a purifying treatment in which both of them are performed.

From the above results, it was found that the decomposition of chlorophyll a (that is, the decomposition of water-bloom) is effective only by UV irradiation, but there is a problem that the treated water becomes cloudy and the decomposed water-bloom floats on the water surface. Also, aluminum sulfate (band) had a higher effect of decomposing chlorophyll a than polyaluminum chloride (PAC), but the pH was greatly lowered, and it was not neutralized over time. .. However, if aluminum sulfate (band) is added at an appropriate molar ratio, it may be possible to suppress the decrease in pH and perform treatment. On the other hand, it was found that the treated water of polyaluminum chloride (PAC) was neutralized. Further, it is understood that polyaluminum chloride (PAC) is more effective than aluminum sulfate (band) in the aggregation effect of soluble phosphorus and soluble nitrogen eluted by ultraviolet irradiation. Therefore, use of polyaluminum chloride (PAC) is recommended from the viewpoint of environmental load. In addition, since the pH may not affect the addition of the coagulant in the degree of the environmental capacity in the natural environment, it can be said that it is possible to cope with the increase in the molar ratio of the coagulant.

In addition, in this experiment, the change with time was recorded and analyzed until 7 to 10 days after treatment with ultraviolet irradiation and addition of a flocculant, but chlorophyll-a was observed 2 to 3 days after the cells were once destroyed. The decomposition effect of was remarkable, and it was verified that the purification treatment of this experiment was effective.

In this experiment, by performing the ultraviolet irradiation at the same time as the addition of the coagulant, the operation such as rapid stirring of the coagulant necessary for the treatment can be substituted by stirring in the ultraviolet irradiation tank. As a result, the water-bloom can be aggregated and precipitated, and the water-bloom can be killed, and the water containing cyanobacteria can be efficiently purified. As described above, the coagulant addition and the ultraviolet irradiation can be performed in different tanks, and even in that case, it is presumed that the same results as the above experimental results can be obtained.

The concentration of water-bloom (chlorophyll a) in the water containing water from Senba Lake used in the experiment was extremely high, 1500 (μg/l) during the test and 1900 (μg/l) after 7 days, but Kasumigaura Since the average concentration of chlorophyll a in the water-bloom containing water is 50 to 100 (μg/l), it can be said that the water-bloom containing water in the experiment was taken from the place where the water-bloom accumulated on the water surface due to wind or the like. .. Therefore, it is confirmed that the method of this experiment can obtain a very large effect by poly-aluminum chloride (PAC) and UV irradiation even for accumulated blue-green algae on the lake shore. When the chlorophyll a concentration of stock solution Aoko is 50-100 (μg/l), it is suggested that the chlorophyll a concentration becomes 10 (μg/l) or less by UV irradiation and addition of polyaluminum chloride (PAC). .. As described above, the concentration of chlorophyll a is below the detection limit in the supernatant after the blue-green algae are precipitated by the irradiation of ultraviolet rays and the treatment with the coagulant. The coagulant addition concentration is recommended to be used in a molar ratio range of 2 to 2.5, but it is also possible to use a molar ratio of 1 or less in the above-mentioned water-containing water with a low algal concentration. ..

As described above, the water-containing water of the present example may or may not be stored in the recovery tank after the purification treatment, that is, it may be discharged as it is, but in the water area where the fishery right exists. When adding a coagulant, it is necessary to collect the remaining sediment (produced sludge). According to the law enforcement regulations concerning the prevention of marine pollution and marine disasters, the pollution classification of harmful liquid substances is classified into X, Y and Z. X-class substances pose a serious risk to marine resources or human health, Y-class substances pose a risk to marine resources or human health, and Z-class substances mean minor risks to marine resources or human health. It brings danger. Since polyaluminum chloride, magnesium hydroxide, etc. are classified as Z group substances, there is a high possibility that they will not be a problem, but it is preferable to collect the remaining precipitate, if necessary, and then discard it. To do. Therefore, if necessary, a purification method using only ultraviolet irradiation can be used in water areas where fishing rights are available. In that case, since the harmful liquid substance is not contained, the remaining precipitate does not have to be recovered, but when recovered, it can be used as a fertilizer or the like.

As described above, according to the water purification apparatus and the water purification method of the present invention, by irradiating ultraviolet rays together with the addition of a coagulant, algae are removed by algae removal, and nitrogen, phosphorus and chlorophyll a in water are removed. The concentration can be lowered to effectively suppress the generation of water-bloom.

The above-described water purification apparatus and water purification method are examples, and the apparatus and method can be appropriately modified without departing from the spirit of the invention. For example, in this example, aluminum sulfate and polyaluminum chloride were used as the aggregating agent, but ferrous sulfate, ferric sulfate, ferric chloride, polyiron chloride, and polymer aggregating agent may also be used. They can be used, or they can be used in combination.

DESCRIPTION OF SYMBOLS 1... Water purification apparatus, 10... Water storage tank, 11, 14, 23, 31, 41, 51... Pump, 12... Piping (hose), 15, 24, 32, 42, 52, 71... Open/close valve, 20... Aggregation Agent mixing tank, 21... Blower blower (centrifugal fan), 22... Diffuser, 30... Coagulant storage tank, 40... UV irradiation tank, 43... UV lamp, 44... Convection plate, 45... Magnetic processor, 50... Recovery Tank, 60... Control device, 70... Settling tank, 100... Ship, 101... Sail, 111... Fixing device.

In order to achieve the above-mentioned object, the invention according to claim 1 is a water purification method for removing water-bloom and purifying water quality, wherein a water-containing water containing chlorophyll a of 1500 (μg/l) or less is used. A water purification method comprising: a step of collecting water; a step of mixing a flocculant in water-containing water and stirring; and a step of irradiating ultraviolet rays having a wavelength of 253.7 nm while convection the water-containing water. Is.
The invention according to claim 2 is the water purification method according to claim 1 , wherein a step of mixing a flocculant in the water-containing water and stirring the mixture, and irradiating the ultraviolet rays while convection the water-containing water It is characterized in that the steps of performing are performed simultaneously.
The invention according to claim 3 is the water purification method according to claim 1 or 2 , wherein the coagulant is aluminum sulfate, polyaluminum chloride, ferrous sulfate, ferric sulfate, ferric chloride. , At least one or more coagulant selected from polyiron chloride and polymer coagulant.

In order to achieve the above object, the invention according to claim 1 is a water purification method for removing water-bloom and purifying water quality without using a photocatalyst, wherein the concentration of chlorophyll a is 1500 (μg/l). ) A step of taking in the following water-containing water, a step of mixing the water-containing water with a coagulant and stirring with a blower blower and a diffuser, and a step of irradiating ultraviolet rays having a wavelength of 253.7 nm while convectioning the water-containing water. And a step of irradiating with the ultraviolet ray at the same time .
The invention according to claim 2 is the water purification method according to claim 1 , wherein the coagulant is aluminum sulfate, polyaluminum chloride, ferrous sulfate, ferric sulfate, ferric chloride, poly. It is characterized by being at least one or more flocculants selected from iron chloride and polymer flocculants.

Claims (7)

A water purification device for purifying water quality by removing cyanobacteria,
Water intake means for taking in blue-green alga-containing water containing blue-green algae,
A coagulant mixing means for mixing the algae-containing water with a coagulant and stirring,
Ultraviolet irradiation means for irradiating ultraviolet rays while convection the cyanobacteria-containing water,
A water purification device having: The water purification apparatus according to claim 1, wherein the coagulant mixing unit and the ultraviolet irradiation unit are combined into one unit. The aggregating agent is at least one or more aggregating agent selected from aluminum sulfate, polyaluminum chloride, ferrous sulfate, ferric sulfate, ferric chloride, polyiron chloride, and polymer aggregating agent. The water purification device according to claim 1 or 2. The water purification apparatus according to claim 1, wherein the wavelength of the ultraviolet rays is 200 to 280 nm. The water purification device according to any one of claims 1 to 4, wherein the water purification device has a boat shape that operates in a water area to be purified. A water purification method for removing blue-green algae to purify the water quality,
A step of taking water containing cyanobacteria,
A step of mixing the algae-containing water with a flocculant and stirring,
Irradiating with ultraviolet rays while convection of the cyanobacteria-containing water,
A water purification method comprising: The water purification method according to claim 6, wherein the step of mixing the algae-containing water with a flocculant and stirring and the step of irradiating with ultraviolet rays while convection of the cyanobacteria-containing water are performed at the same time.