JP2021000577A - Water quality purifying system - Google Patents

Abstract

To provide a water quality purifying system capable of removing nitrate nitrogen, phosphate phosphorus, and suspension particles to maintain good water quality stably without causing water quality to be deteriorated due to an organic substance or the suspension particles discharged from a denitrifying device.SOLUTION: A water quality purifying system of this invention is constituted of: a denitrifying device that removes nitrate nitrogen included in treatment water under an aerobic condition; and a froth separation device that removes suspension particles included in the treatment water, suspension particles eluted from filter media charged into the denitrifying device, suspension particles formed by microorganisms proliferated or particles captured in the denitrifying device detaching therefrom, and suspension particles formed by a denitrifying reaction. The denitrifying device is a sprinkling filter bed-type denitrifying device that exposes at least a part of the filter media to air by supplying the treatment water from above a denitrifying tank and passing the treatment water without being retained in the denitrifying tank.SELECTED DRAWING: Figure 1

Description

The present invention provides a water purification system for removing nitrate nitrogen, phosphate phosphorus and suspended particles in water, more specifically, denitrification and dephosphorification under aerobic conditions for breeding fish and shellfish. It relates to a water quality purification system including a denitrifying device having a dephosphorifying function that can be performed, a suspension particle dispersed in breeding water, and a foam separation device for removing suspended particles discharged from the denitrifying device.

When breeding fish and shellfish such as aquaculture and farming, organic suspended particles such as ammonia and body surface mucus are discharged from the fish and shellfish, and the water quality of the breeding water deteriorates. In particular, in the closed circulation method in which fish and shellfish are bred without exchanging water, ammonia and organic suspended particles rise to a concentration unsuitable for breeding, so a water purification device is installed to reach a concentration suitable for fish and shellfish. Must be lowered.
Conventional aquaculture equipment is only equipped with a nitrifying device that converts toxic ammonia into harmless nitric acid by the action of nitrifying bacteria that propagate on filter media such as coral, and it is difficult to maintain good water quality for a long period of time. there were. In particular, since organic suspended particles such as nitric acid and body surface mucus were considered to have low toxicity, denitrification devices and foam separation devices were rarely installed, but in recent years, causes of poor growth and mortality. It turned out to be one of the substances and has come to be installed. In addition, nitrogen and phosphorus contained in aquaculture wastewater are substances that cause environmental pollution, so it has become necessary to treat them before releasing them into rivers and the sea.

Since the conventional denitrification device is anaerobic denitrification in which nitric acid is reduced to nitrogen gas by denitrifying bacteria under anoxic conditions, there is a high risk of hydrogen sulfide generation, and it is rarely used for breeding fish and shellfish. In recent years, in the presence of cellulose, an aerobic denitrification method that reduces nitric acid to nitrogen gas by the action of aerobic denitrifying bacteria has been developed and has come to be used for fish and shellfish breeding. For aerobic denitrification, drainage is performed intermittently using the siphon principle, and the filter medium holding the denitrifying bacteria alternates between air exposure and liquid immersion, and the treated water is discharged below the filter medium. Breeding water is sprayed from the upper part of the denitrification tank provided with an outlet, and the breeding water flows through the gaps between the filter media without collecting the breeding water in the denitrification tank, so that the filter medium holding the denitrifying bacteria is exposed to air. There is a watering filter type that creates a liquid immersion part.

To remove the suspended particles dispersed in the breeding water, the breeding water in which the suspended particles are dispersed is passed through a filter tank filled with a filter medium, and the suspended particles are captured and removed in the gaps between the filter media by the detention action generated between the filter media. Using the filtration method and the property of adsorbing and concentrating substances at the interface of air bubbles, breeding water and air bubbles are supplied to the separation tank, and the airborne particles adsorbed by the suspended particles are removed to remove the suspended particles from the breeding water. There is a foam separation method to remove.

In the filtration method, when a large amount of suspended particles are treated, the filter medium becomes clogged, and it is necessary to wash and remove the accumulated suspended particles. In addition, organic substances eluted from the body surface mucus and the filter medium of the denitrifying device, which are the largest causative substances of water quality deterioration, cannot be easily removed due to their small particle size, and stay in the breeding water for a long period of time to cause water quality deterioration.

On the other hand, in the foam separation method, bubbles and suspended particles are adsorbed by a hydrophobic bond, so that the suspended particles need to have a hydrophobic site like a protein, and hydrophilic suspended particles such as sand are used. It cannot be adsorbed on air bubbles and cannot be removed from breeding water. In order to remove suspended particles that are not adsorbed by bubbles such as sand by the foam separation method, it is necessary to adsorb the hydrophilic suspended particles to the bubbles and to supply a chemical for forming a layer of bubbles on the water surface. .. For example, in order to remove the kaolin particles dispersed in the liquid, a casein solution having a hydrophobic site and having a property of adsorbing to the kaolin particles is added using a chemical injection pump. Casein is adsorbed with kaolin particles in a liquid, and the kaolin particles are changed into suspended particles (casein-kaolin particles) having a hydrophobic site that can be adsorbed on bubbles, so that the casein can be removed from the liquid.

Phosphoric acid can be removed by adding calcium or magnesium to atomize phosphoric acid and separating and removing it (HAP method, MAP method), or by performing anaerobic treatment and aerobic treatment to allow microorganisms to absorb phosphoric acid and remove it. The method (AO method) is known. However, both methods were not used in aquaculture where productivity was important due to their high cost and complicated operation.

Japanese Patent No. 4602446 Japanese Patent No. 6480015

Nitrate nitrogen is generally removed by anaerobic denitrification with the dissolved oxygen concentration in the water to be treated set to zero, but in closed-circulation aquaculture in which the treated water from the denitrification device is returned to the breeding tank, the breeding tank is used. Extra energy is required to aerate the water before returning it to raise the dissolved oxygen concentration to the same level as the breeding water. In addition, anaerobic denitrification has a high risk of generating toxic hydrogen sulfide. Therefore, even if hydrogen sulfide is not generated by using a measuring device or batch processing is performed, it can be placed in the breeding water tank. It prevents hydrogen sulfide from flowing in. Therefore, regular maintenance and regular replacement are required so that the measuring device does not cause erroneous measurement, and the initial cost and running cost become high. In addition, batch processing requires an extra drainage process, which leads to an increase in the size of the equipment and an increase in initial cost.

Aerobic denitrification is an intermittent filtration method in which water to be treated is generally passed through a filter medium in which aerobic denitrification bacteria have propagated, immersed in a liquid, and then drained by the siphon principle to expose the filter medium in the air. Is used. The intermittent filtration method is a safe treatment method in which the filter medium is regularly exposed to air, so that it does not become anaerobic and hydrogen sulfide is not generated. Further, in closed circulation aquaculture, the pretreatment step of reducing the dissolved oxygen concentration of the breeding water to zero and the aeration step of the treated water are not required, and the device becomes smaller, so that the initial cost is reduced.

However, since the intermittent filtration type drains water using the siphon principle, it is necessary to install it at a position higher than the water tank that sends the treated water, and a sturdy mount is required. Further, since drainage is performed at regular intervals, the water tank to which the water is sent needs an extra volume corresponding to the amount of water discharged from the denitrification tank at one time.

In addition to the intermittent filtration type, aerobic denitrification is performed by spraying a liquid like a fountain from the upper part of the denitrification tank and arranging a treated water discharge port at the lower part of the denitrification tank so that the water to be treated does not collect in the denitrification tank. A watering filter method is used in which nitrate nitrogen is treated while the water to be treated flows. Like the intermittent filtration type, the sprinkler filter type must be installed at a higher position than the water tank that sends the treated water, but since the water to be treated is not stored in the denitrification tank, a sturdy stand is not required.
However, since the water to be treated is sprinkled from the upper part of the filter medium, the filter medium is severely worn and the running cost is high. Further, since the organic matter which is a component of the filter medium is eluted, the nitrate nitrogen in the treated water is reduced, but the concentration of the organic matter and the suspended particles is increased and the water quality is deteriorated.

As the dephosphorization technique, the MAP method and the HAP method are used in water treatment. The MAP method and the HAP method are methods in which phosphate ions contained in a liquid are reacted with ammonium ions, magnesium ions, and calcium ions to form insoluble phosphate particles, which are precipitated or filtered. In the MAP method and the HAP method, calcium ions and magnesium ions in the liquid are reduced, which causes growth inhibition in shellfish farming and causes a decrease in production efficiency. Furthermore, the treatment cost is high because chemicals are added, the treatment time is long, and regular cleaning is required due to clogging.

Since the foam separation method has the property of removing only suspended particles that are foamable and have hydrophobic groups in the molecule, the treatment performance varies depending on the water quality of the water to be treated. For stable treatment, even suspended particles that do not have a hydrophobic group can be adsorbed to bubbles and removed, so that proteins, etc. that have effervescent and hydrophobic groups and that have bubbles and suspended particles It is necessary to add a substance that has the property of adsorbing to both, which increases the cost.

An object of the present invention is to consider a substance discharged from a denitrifying device, for example, an organic substance eluted from a denitrifying device filter medium, by using a denitrifying device and a foam separating device in combination in view of the above-mentioned problems of the prior art. , Reaction products generated in the denitrification and dephosphorification process, microorganisms that have taken up phosphorus, and dead microorganisms are removed by the foam separator, and the water quality is not deteriorated by the organic substances and suspended particles discharged from the denitrification device. It is to provide a water purification system that removes nitrates and phosphoric acids. In addition, by using a sprinkling filter as the treatment method for the denitrification device and simultaneously performing denitrification and dephosphorification with the filter medium filled in the denitrification tank, there is no risk of hydrogen sulfide generation, and the denitrification is compact and easy to install. To provide the device. Furthermore, by adding a component that enhances foamability and adsorption to air bubbles to the filter medium of the denitrifying device, and the substance eluted from the filter medium of the denitrifying device becomes a foaming agent and an adsorbent, it is suspended in the water to be treated. It is to provide a water purification system capable of increasing the removal efficiency of particles and maintaining stable and good water quality.

In order to solve the above problems, the present invention
A denitrifying device that removes nitrate nitrogen contained in the water to be treated under aerobic conditions,
Suspended particles contained in the water to be treated, suspended particles eluted from the filter medium filled in the denitrifying device, suspended particles generated by exfoliation of microorganisms propagating in the denitrifying device or captured particles, denitrification Consists of a foam separator that removes suspended particles produced by the reaction
The denitrification device includes a denitrification tank to which water to be treated is supplied, a filter medium for holding denitrifying bacteria filled in the denitrification tank, and a treated water discharge port arranged below the denitrification tank. Prepare,
It is characterized in that at least a part of the filter medium is exposed to air by supplying the water to be treated to the denitrification tank from above and passing the water to be treated through the denitrification tank without accumulating it.

The denitrification device is characterized in that denitrification and dephosphorification are carried out on the same filter medium under aerobic conditions, and nitrate nitrogen and phosphate phosphorus are removed from the water to be treated. However, unlike nitrogen, phosphorus does not gasify, so phosphoric acid phosphorus removed from the water to be treated is taken into the body of microorganisms or atomized and captured by the filter medium, resulting in a denitrification device. It remains inside. Even when suspended particles containing phosphoric acid phosphorus are separated from the filter medium of the denitrification device and resupplied into the water to be treated, the phosphoric acid in the water to be treated can be removed by removing it from the system with the foam separation device. Phosphorus does not increase.

If the water to be treated that is sent to the denitrification device contains suspended particles, the filter medium and the water supply pipe to be treated are clogged. Therefore, the present invention is characterized in that clogging of the filter medium and the water supply pipe to be treated is prevented by using the treated water treated by the foam separating device as the water to be treated to be sent to the denitrification device. The treated water of the foam separating device does not have to be the treated water immediately after the foam separating device such as the treated water of the vitrifying device.

In the denitrification device, in order to maximize the treatment capacity, a baffle plate for evenly dispersing the water to be treated is arranged between the filter medium and the water supply port to be treated, so that the water to be treated is placed on the surface of the filter medium. Is characterized in that water is evenly distributed. Further, by disposing the baffle plate, the impact force on the filter medium generated by the supply of water to be treated can be alleviated, and the amount of suspended particles discharged from the filter medium can be reduced.

By adding a foamable substance to the filter medium to be filled in the denitrification device, the foam separation device can function even when the water to be treated does not have foamability. The effervescent substance to be added is not limited as long as it is a substance that changes its properties by a denitrification reaction and causes effervescence even if the additive substance itself does not have effervescence.

Further, by adding a substance having a property of being adsorbable to both bubbles and suspended particles to the filter medium filled in the denitrifying device and eluting the substance added to the filter medium, the substance is adsorbed to the bubbles without a hydrophobic group. It is characterized in that even suspended particles having no property can be removed from the water to be treated by a foam separator. The optimum substance to be added is a surface-active substance such as casein, but the substance is not limited as long as it has a hydrophobic group and is adsorptive to suspended particles. Further, even if the additive substance itself does not have a hydrophobic group and is not adsorbed on the suspended particles, it is limited as long as the substance changes its properties due to the denitrification reaction and is adsorbed on both the bubbles and the suspended particles. It is not something that is done.

According to the water purification system according to the present invention, the following effects are obtained.
According to the present invention, by removing organic suspended particles such as cellulose eluted from the filter medium of the denitrifying device with the foam separator, the organic substances derived from the denitrifying device do not accumulate in the water and are in the water to be treated. Nitrate nitrogen and phosphate phosphorus can be efficiently removed, and stable water quality can be maintained for a long period of time.

According to the present invention, there is no risk of hydrogen sulfide generation because at least a part of the filter medium filled in the denitrifying device is exposed to air. Also, unlike anaerobic denitrification, the process of reducing the dissolved oxygen concentration to zero and the process of returning the dissolved oxygen concentration to the state before treatment are not required, so not only the energy required for aeration can be reduced, but also the device becomes compact and the cost is reduced. It will be reduced.

According to the present invention, since the denitrification reaction and the dephosphorification reaction can be carried out with the same filter medium, the apparatus can be made compact and the initial cost can be reduced. In addition, nitrate nitrogen is released into the atmosphere as nitrogen gas by denitrifying bacteria via water, but phosphate phosphorus is vaporized and cannot be removed from water, so it is necessary to remove it outside the system. It is necessary to use a physical method such as cleaning the filter medium. However, cleaning the filter medium is not only hard work but also causes deterioration of processability. When suspended particles containing phosphoric acid such as microorganisms are redispersed in the liquid from the filter medium, they are removed from the water using a foam separator to remove the substance containing phosphoric acid from the filter medium without washing the filter medium. Can be removed.

According to the present invention, since the water to be treated does not collect in the denitrification tank filled with the filter medium of the denitrification device, the weight of the device during operation can be reduced, the strength of the gantry can be reduced, and the initial cost can be reduced. it can.

According to the present invention, by disposing a baffle plate between the filter medium of the denitrification device and the water supply port to be treated, the water to be treated can be evenly supplied to the surface of the filter medium, and nitrate nitrogen and phosphoric acid can be supplied. The efficiency of removing state phosphorus is improved. Since the removal efficiency is high, the device becomes compact and the initial cost can be reduced. Further, since the impact force of the water to be treated supplied to the denitrification device to the filter medium can be alleviated by using the baffle plate, the amount of organic suspended particles discharged from the filter medium, which causes water pollution, is reduced. As a result, the amount of filter media wear is reduced and the running cost is reduced.

According to the present invention, it is possible to prevent clogging of the filter medium of the denitrification device and blockage of the water supply pipe to be treated, and it is possible to reduce the initial cost and the running cost by eliminating the need for cleaning or replacement.

According to the present invention, even if the water to be treated has no or little foaming property, a foaming substance or a substance that changes the properties of the foaming substance during the denitrification reaction is added to the filter medium to be filled in the denitrification device. By eluting the treated water as it passes through the filter medium, the foam separator can function and stable treatment can be performed.

According to the present invention, even suspended particles that cannot be removed by the foam separator because they do not contain hydrophobic groups and do not have the property of adsorbing to bubbles have the property of adsorbing to both bubbles and suspended particles in the filter medium filled in the denitrifying device. By adding the substance to be treated and eluting the water to be treated as it passes through the filter medium, the foam separation device can function and can be easily removed from the water to be treated.

Schematic block diagram of the water purification system according to the embodiment of the present invention Schematic configuration diagram showing a cross-sectional view of the denitrifying apparatus of the present invention. The conceptual diagram which showed the internal flow of the denitrification apparatus which arranged the baffle plate of this invention. Schematic configuration of a closed circulation type seafood breeding system incorporating the water purification system according to the embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail together with the illustrated examples, but the present invention is not limited to the following embodiments, and can be appropriately modified and implemented. FIG. 1 is a schematic configuration diagram of a water purification system according to an embodiment of the present invention. The water purification system 1 of the present invention is a system for treating nitrate nitrogen, phosphoric acid phosphorus, body surface mucus excreted by fish and shellfish, and suspended particles discharged from the denitrifying device 2, and is a denitrifying device. 2. It is composed of a foam separating device 3. The size of the suspended particles is not limited, and colloidal particles such as proteins are also included.

The denitrification device 2 includes a denitrification tank 21, a filter medium 22 for holding denitrifying bacteria, a watering nozzle 23 for sprinkling treated water into the denitrification tank, and a treated water discharge port 24 (FIG. 2). The water to be treated supplied to the watering nozzle 23 by the pump 5 or the like is uniformly sent to the surface of the filter medium through a large number of holes opened in the watering nozzle 23. The water to be treated that has been sent to the surface of the filter medium passes through the gap of the filter medium 22 and is sent to the treated water discharge port 24 at the bottom of the denitrification tank. By providing the treated water discharge port 24 at the lower part of the denitrification tank 21, the water to be treated is drained from the treated water discharge port 24 without accumulating in the denitrification tank 21. Since the amount of water to be treated is not sufficient to fill all the gaps in the filter medium 22, the filter medium 22 contains a mixture of a portion 22a in contact with the water to be treated and a portion 22b exposed to air, and is combined with the water to be treated. Nitrate nitrogen is taken up by denitrifying bacteria at the contacting portion 22a, and oxygen in the air is taken up at the air-exposed portion 22b. Air can be supplied to the denitrification tank 21 with a blower or the like to disperse the water to be treated so that a filter medium that the water to be treated does not come into contact with is not generated.

FIG. 3 is a conceptual diagram showing the baffle plate 25 arranged in the denitrification device 2 of the present invention and the internal flow of the denitrification device 2. The water to be treated is sent to the watering nozzle 23 arranged above the filter medium by a pump or the like, and is sprinkled in a conical shape toward the filter medium 22. The watering nozzle 23 may be a nozzle in which a hole is simply formed in the pipe shown in FIG. 2 which does not require pressure, in addition to the nozzle which applies pressure to supply the water to be treated in a spray form.
A baffle plate 25 is arranged between the watering nozzle 23 and the filter medium 22, and the sprinkled water to be treated collides with the baffle plate 25 to reduce the speed, and a large number of water is open to the baffle plate 25. Since the water to be treated flows from the holes toward the filter medium 22, the water to be treated is evenly distributed without giving an impact to the filter medium 22. The baffle plate 25 is optimally provided with a large number of circular holes, but if it cushions the impact of the water to be treated, such as a grid-like net, and evenly disperses the water to be treated on the surface of the filter medium, the shape There are no restrictions.

The filter medium 22 filled in the denitrification tank 21 is preferably porous in structure because denitrifying bacteria that denitrify under aerobic conditions propagate, but it is particularly limited as long as it can retain the denitrifying bacteria. It is not something that is done. Further, the filter medium 22 contains an organic substance necessary for the denitrification reaction, and a substance having cellulose or a cellulose skeleton is the best, but the substance is not limited as long as it can be used by denitrifying bacteria.

The foam separation device 3 supplies bubbles to the separation tank 32 containing the water to be treated by the bubble feeder 33, adsorbs the suspended particles in the water to be treated to the bubbles, and adsorbs the suspended particles formed on the water surface. It is a device that removes suspended particles from the water to be treated by removing the layer of. The bubble feeder 33 generates a negative pressure region in the rotor by rotating the rotor at high speed, supplies air to the rotor by the pressure difference from the atmosphere, and refines the air by the shearing force of the rotor to be covered. The bubble supply mechanism for supplying air into the treated water is the best, but the device is not limited as long as it can supply air bubbles.

FIG. 4 is a schematic configuration diagram of a closed circulation type seafood breeding system incorporating the water purification system 1 according to the embodiment of the present invention. The closed circulation type fish and shellfish breeding system 8 includes a water purification system 1 of the present invention, a nitrifying device 6 for converting ammonia nitrogen in breeding water into nitrate nitrogen by the action of nitrifying bacteria, and a pump 5 for circulating breeding water. Although not shown, it is equipped with a water temperature adjusting device. The nitrifying apparatus 6 is composed of a nitrifying tank 61 and a filter medium 62 for holding nitrifying bacteria. Depending on the type of seafood, equipment such as a sterilizer and an oxidizing device such as ozone may be incorporated.

The breeding water overflows and is sent to the foam separation device 3 and the nitrification device 6, and the nitrification device treated water is sent to the denitrification device 2 and the breeding aquarium 7 by the pump 5. The treated water of the denitrifying device is returned to the foam separating device 3 from the treated water discharge port 24 arranged below the bottom of the filter medium of the denitrifying device 2. The denitrifying device treated water may be returned to the nitrifying device 6 or the breeding aquarium 7 instead of the foam separating device 3.

(Example 1)
A breeding aquarium and a purification device (nitrification device, denitrification device, foam separation device) were installed (experimental area), and seawater in the breeding aquarium was sent to the purification device using a pump. The breeding water treated by the purification device was returned to the breeding aquarium again. Abalone was placed in the breeding aquarium and a mixed feed for abalone farming was given once a day. The breeding water temperature was adjusted to 18 to 20 degrees with an air conditioner. As the filter medium, ceramics and a string-like contact material were used for ammonia nitrification, and cellulose was used for denitrification. The animals were bred by replenishing tap water for evaporation and artificial seawater for reduction due to bubbles discharged by the foam separator without exchanging seawater.

Table 1 shows the water quality one month after the start of the experiment. The system in which the nitrification device and the foam separation device are installed and only the denitrification device is not installed is defined as the control group 1, and the system in which the nitrification device and the denitrification device and the foam separation device are not installed is defined as the control group 2. Both systems are bred under the same conditions. did.
As shown in Table 1, it was confirmed that the experimental group had less nitrate nitrogen and phosphoric acid phosphorus than the control groups 1 and 2. It was confirmed that nitrate nitrogen and phosphate phosphorus were removed at the same time by denitrifying under aerobic conditions using cellulose as a filter medium and removing suspended particles with a foam separator.

(Example 2)
A breeding aquarium and a purification device (nitrification device, denitrification device, foam separation device) were installed, and seawater in the breeding aquarium containing abalone was sent to the purification device using a submersible pump. The breeding water treated by the purification device was returned to the breeding aquarium again. At the start of the test, the foam separator was not operated.

One day after the start of the test, the breeding water became cloudy and the abalone began to die, so the operation of the foam separator was started. When the foam separator was operated, a large amount of stable foam was generated, and one day after the start of operation, the breeding water, which was cloudy, became transparent. It was confirmed that the suspended particles eluted from the filter medium of the denitrifier can be removed from the water by the foam separator.

1 Water purification system 2 Denitrification device 21 Denitrification tank 22 Denitrification filter medium 22a Liquid contact part 22b Air exposure part 23 Sprinkling nozzle 24 Treated water drain port 25 Obstacle plate 3 Foam separation device 31 Separation tank 32 Bubble feeder 4 Water tank 5 Pump 6 Nitrification device 61 Nitrification tank 62 Nitrification filter media 7 Breeding aquarium 8 Closed circulation type fish and shellfish breeding system

Claims (5)

A denitrifying device that removes nitrate nitrogen contained in the water to be treated under aerobic conditions,
It is composed of a foam separator that removes suspended particles contained in the water to be treated and suspended particles contained in the treated water of the denitrification device.
The denitrification device includes a denitrification tank to which water to be treated is supplied and
A filter medium that holds bacteria that perform denitrification and is filled in the denitrification tank.
A treated water discharge port arranged below the denitrification tank is provided.
A water purification system characterized in that at least a part of a filter medium is exposed to air by supplying water to be treated to the denitrification tank from above and passing the water to be treated through the denitrification tank without accumulating it. The water purification system according to claim 1, wherein the denitrifying device has a function of removing phosphoric acid phosphorus. The water purification system according to claim 1 or 2, wherein the water to be treated by the denitrification device is treated water by a foam separator. The water quality purification system according to claim 1 to 3, wherein a baffle plate is arranged between the water supply port to be treated and the filter medium of the denitrification device. The filter medium of the denitrification device is characterized by adding a substance having foamability or increasing foamability, and a substance increasing the adsorptivity between bubbles supplied by the foam separator and suspended particles in the water to be treated. The water purification system according to claims 1 to 4.

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