JPH04326987A - Water treatment apparatus for preventing growth of algae in landscape basin - Google Patents

Abstract

PURPOSE:To prevent the formation of algae in a landscape basin by mounting an iron column provided on the outlet side of an ozone reaction tank in series and catching phosphorus in refluxed water as insoluble iron phosphate by iron hydroxide formed by bringing the residual ion in refluxed water into contact with metal iron. CONSTITUTION:Water 2 to be treated is introduced into the upper part of an ozone reaction tank 4 from a landscape basin 1 by a water pump 3. Air raised in its pressure by a blower 5 is sent to an ozone generator 6 and dehumidified/dried by a dehumidifier while the dried air enters a discharge tube to generate ozone to be taken out as ozonized air 7 and air bubbles are introduced into the ozone reaction tank 4 through a diffuser 8. In this tank 4, the ozone gas diffused from the lower part of the tank 4 comes into contact with the water to be treated flowing in the tank 4 from above to perform the killing of algae, discoloration and deodorizing. After reaction, the water to be treated is sent to an iron column 10 as ozone treated water 9 and, in the iron column, a metal iron material 11, dissolved ozone and ferric hydroxide catch phosphorus in water as iron phosphate to lower the concn. of phosphorus and treated water 12 is returned to the original landscape basin 1.

Description

[Detailed description of the invention]

[Object of the invention]

0002

[Industrial Application Field] The present invention prevents the formation of algae in landscaped ponds at golf courses, etc., thereby eliminating greening and discoloration of the pond water, maintaining transparency, and maintaining the landscape of landscaped ponds. This invention relates to a water treatment device for preventing algae formation in ponds.

0003

[Prior Art] Scenic ponds at golf courses and the like become eutrophic due to the runoff of domestic wastewater and fertilizers, and especially in the summer when the water temperature rises, algae grow significantly, causing the pond water to turn green and become opaque. , there is a problem that the scenery as a scenic pond is damaged.

[0004] In general, methods for preventing algae formation in pond water include (1) adding a chemical agent with an algaecide effect to the pond, and (2) cyclical algaecide treatment of pond water using ultraviolet rays, ozone, etc. be.

In method (1) above, chemical agents are used, such as copper ions (copper sulfate added with Cu2+ at an amount of 0.1 to 0.5 ppm) or chlorine (sodium hypochlorite added with an effective chlorine amount of 0.5 to 3 ppm). ) is used. Method (2) has a sufficient algaecidal effect, but it does not have the same lasting effect as chemical agents, so it is necessary to continuously circulate the pond water.

[0006]

[Problem to be solved by the invention] As mentioned above, (1)
Copper sulfate or sodium hypochlorite are used to kill algae and prevent algae formation by adding chemical agents, but these are highly toxic substances and must be managed to prevent them from entering the pond in large quantities due to accidents. This requires careful attention, as it has a particularly large impact on fish species such as carp and carp, and there is also the problem of causing mistrust among local residents due to concerns about wide-area environmental pollution.

In addition, in (2) cyclical algaecide treatment using ultraviolet rays and ozone, although ultraviolet irradiation and ozone treatment have excellent algaecidal effects, they do not have the sustained effect of chemical agents, so the treatment flow rate is low. If the capacity of the scenic pond is too small, it will not be possible to suppress the growth of algae in the pond water.

[0008] Particularly in summer, the growth rate of algae is high, and the treatment circulation rate is 2 to 4 times per day.
More than one turn/day is required, and the capacity of the scenic pond is 10.0
00m3 and the circulation rate is 3 turns/day, the treatment flow rate is 3 x 10,000m3/day, or 1,250
m3/h, requiring large-scale processing equipment.

The present invention was made in consideration of the above problems, and instead of adding chemicals that may cause environmental pollution or harm to fish, it uses environmentally friendly ultraviolet rays and ozone for recycling treatment at a low circulation rate. By effectively utilizing
The purpose is to provide a high-performance, low-cost water treatment device that prevents the formation of algae in scenic ponds. [Structure of the invention]

0010

[Means and actions for solving the problem] Ozone treatment is optimal for the circulation treatment of landscape ponds because it has an excellent algaecidal effect and can also be expected to have decolorizing and deodorizing effects, but ozone treatment has a long-lasting effect like that of chemical agents. Therefore, in order to prevent algae formation with ozone treatment alone, a sufficient treatment circulation rate (2
~4 turns/day). The cost of ozone treatment is approximately proportional to the treatment flow rate, so for example, the treatment circulation rate is 2 to 4.
If turn/day is reduced by 1/3 turn/day, the cost is 1
/6 to 1/12, but it is not sufficient to prevent the generation of algae.

[0011] As a result of studying methods to prevent algae formation even in low flow rate treatment, the inventors focused on dissolved phosphorus (P), which is an essential component for algae growth, and by intensively removing phosphorus at the same time as ozone treatment. It was found that even low-flow ozone treatment was sufficient to prevent algae formation.

[0012] Phosphorus, nitrogen, BOD (
biochemical oxygen demand) are essential components.
We confirmed the growth of algae in response to these component concentrations. First, pure water (added Na2 HPO4 ・12H2 O),
Nitrogen (NH4 Cl added) and BOD (sodium glutamate C5 HgO4 and glucose C6 H12
A solution prepared by adding O6 to a specified concentration is used as raw water, and this raw water is placed in a beaker. Next, algae are inoculated and left outdoors.
The algae growth rate was determined from the standing time and absorbance.

[0013] Figure 2 shows the measurement results of the growth rate of algae with respect to phosphorus, nitrogen and BOD concentrations. As can be seen from Figure 2,
Regarding phosphorus, it was found that when the concentration in water exceeds 0.05 mg/liter, algae proliferation increases rapidly. Concerning nitrogen and BOD, the influence of water concentration was small, and algae growth was observed even at zero concentration. The above results confirmed that the phosphorus component has a great influence on the growth of algae, and that if the phosphorus concentration in water can be reduced to 0.05 mg/liter or less, the growth of algae can be prevented. The phosphorus concentration in ordinary rivers is over 0.1 mg/liter, and in polluted lakes and marshes it can be over 10 mg/liter.

Methods for removing phosphorus from water include activated sludge method, coagulation-precipitation method using aluminum sulfate, PAC (polyaluminum chloride), ferric chloride, etc., and crystallization dephosphorization method. Both of these methods have problems in application to dephosphorization treatment of scenic ponds due to cost.

[0015] For this reason, the inventors investigated a treatment method that can dephosphorize at a low cost, and as a result, they made use of the dissolved ozone remaining after the ozone treatment, and made metallic iron act on the dissolved ozone to convert the iron into a high-quality metal. We have invented a method for removing phosphorus by oxidizing it to (trivalent) iron and forming insoluble and stable iron phosphate (FePO4) with the trivalent iron and phosphorus.

[0016] Various types of iron scraps can be used as the metal iron used in the present invention, and the column is filled with water so that it can be backwashed. After use, it can be reused as iron scraps, so it is low Dephosphorization treatment becomes possible at low cost.

FIG. 3 shows the processing contents of each part in the water treatment according to the present invention. Water to be treated is introduced from the scenic pond (water volume Vm3), which is the target of algae generation prevention, to the ozone treatment device, and the treatment flow rate is is 1/2 to 1/3 to reduce costs.
Turn/day, that is, V/2 to V/3 m3/day. In the ozone treatment device, the water to be treated is completely killed by ozone oxidation, and at the same time, the water is decolorized and deodorized. The ozonated water that leaves the ozone treatment equipment contains about 0.2 to 2 mg/liter of dissolved ozone, depending on the treatment conditions, and the ozonated water containing this dissolved ozone is passed to the iron column installed at the subsequent stage. be introduced.

In the iron column, the following formula 2Fe+O3 +3H2 O→2Fe(OH)
3 2Fe(OH)3 +2PO4 3-→2
FePO4 +6OH- (2Fe+O3 +
2PO4 3-+3H2 O=2FePO4 +6OH
- As shown in ), the filled metallic iron first reacts with dissolved ozone to form a higher-order compound, ferric hydroxide Fe (
OH)3, which is dissolved phosphorus (phosphate ion P
O4 3-) to form insoluble iron phosphate FePO4 and fix phosphorus, reducing dissolved phosphorus to 0.05
The dephosphorized water that exits the iron column is returned to the scenic pond, and through this continuous circulation process, the phosphorus concentration in the scenic pond is reduced to below 0.05 mg/liter. This makes it possible to effectively prevent algae formation even at low treatment circulation rates.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the water treatment apparatus for preventing algae formation in a scenic pond according to the present invention will be described below with reference to the drawings. FIG. 1 is a system diagram showing an embodiment of a water treatment device for preventing algae formation in a scenic pond according to the present invention, in which water 2 to be treated is sent from a scenic pond 1 to be treated to an ozone reaction tank 4 by a water supply pump 3. Air introduced from the top and pressurized by the blower 5 is sent to the ozone generator 6, where it is dehumidified and dried by the dehumidifier provided in the device, and then enters the discharge tube to generate ozone.
It is taken out as ozonized air 7 and bubbles are introduced through a diffuser 8. Here, the ozone gas diffused from the lower part and the water to be treated flowing in from the upper part come into gas-liquid contact to kill algae, decolorize, and deodorize, and after the reaction, the ozone-treated water 9 is sent to the next iron column 10.

By the way, the iron column 10 is filled with a metal iron material 11 of pure iron or an iron alloy in the form of chips, cuttings, granules, rods, or tubes so that the column can be used for water flow and backwashing. The secondary hydroxide produced by the dissolved ozone contained in the water and the metal iron filled in the water is
The iron captures phosphorous in the water as iron phosphate FePO4, reducing the phosphorus concentration to 0.05 mg/liter or less, and the dephosphorized treated water 12 is returned to the scenic pond.

On the other hand, the residual ozone gas after the gas-liquid contact in the ozone reaction tank 4 is discharged from the upper part as waste ozone 13, then enters the waste ozone decomposer, and is completely decomposed by the ozone decomposer 15 filled. It is released into the atmosphere as harmless oxygen. By continuously carrying out the above operations, the treatment of the stagnant water in the scenic pond can be effectively carried out using a small amount of ozone.

[0022]

Effects of the Invention As explained above, the water treatment device for preventing algae formation in landscaped ponds according to the present invention can kill algae by ozone treatment,
In addition to decolorizing and deodorizing, we use dissolved ozone and inexpensive metal iron materials such as iron scraps packed into an iron column to remove phosphorus from the water to a concentration of 0.05 mg/liter or less, which makes it difficult for algae to grow. This makes it possible to prevent algae formation at low treatment circulation rates, which cannot be achieved with ozone treatment alone, making it possible to realize a treatment device with higher performance, higher reliability, and lower cost than conventional devices.

[Brief explanation of drawings]

FIG. 1 is a system diagram showing an embodiment of a water treatment device for preventing algae formation in a scenic pond according to the present invention.

FIG. 2 is a characteristic diagram showing the relationship between algal growth rate and phosphorus and nitrogen/BOD concentrations in water.

[Figure 3] Interrelation diagram of algae generation prevention water treatment functions.

[Explanation of symbols]

1...Scenic pond, 2...Water to be treated, 3...Water pump, 4...Ozone reaction tank, 5...Blower, 6...Ozone generator, 7...Ozonized air, 8...Diffuser, 9...Ozonated water, 10 …
Iron column, 11... Metallic iron material, 12... Treated water, 13... Exhaust ozone, 14... Exhaust ozone decomposer, 15... Ozone decomposer.

Claims (1)

[Claims] Claim 1: An ozone generator that supplies ozonized air, and an ozone generator that brings the water to be treated from the landscape pond into gas-liquid contact with the ozonized air to oxidize, kill algae, and decolorize the water to restore the original landscape. An ozone reaction tank for refluxing water to the pond and an iron phosphate insoluble in phosphorus in the reflux water are installed in series on the outlet side of the ozone reaction tank, and iron hydroxide is produced by bringing the residual ions in the reflux water into contact with metal iron. A water treatment device for preventing the formation of algae in landscaped ponds, characterized by being equipped with an iron column that captures algae.