JP2004066137A - Water treatment equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make efficiently treatable a waste water containing an organic material without necessitating the removal of residual chlorides such as sodium chloride. <P>SOLUTION: This water treatment equipment is provided with an electrolysis cell 10 provided with a cathode plate 11a having a property of producing chlorine in water by energizing and an anode plate 11b, a reaction vessel 20 provided with a heater 21 for heating water treated in the electrolysis cell 10 and a gas dissolving apparatus 30 for dissolving chlorine gas produced in the electrolysis cell 10 into the water in the reaction vessel 20. As a result, the chlorine gas produced in the electrolysis cell 10 is dissolved in the water in the reaction vessel 20 by the gas dissolving apparatus 30 and the water kept normally at a temperature of 40-60°C with the heater 21 in the reaction vessel 20 exhibits remarkably high oxidation. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
TECHNICAL FIELD The present invention relates to a water treatment apparatus for treating wastewater in factories, livestock farms, human waste treatment plants, industrial waste disposal sites, and the like.
[0002]
[Prior art]
Wastewater containing organic matter, for example, wastewater from factories, livestock farms, human waste treatment plants, industrial waste disposal sites, and the like, is treated by an aeration method using microbial treatment, that is, an activated sludge method. Decomposition of wastewater containing pigment by the activated sludge method has been attempted, but it has been particularly difficult to decompose the color of manure in livestock farms and human waste treatment plants.
[0003]
As a treatment of such organic colored wastewater, Japanese Patent Application Laid-Open No. Hei 7-256297 discloses a method in which salt is added to a waste liquid and then decomposed by applying electricity. Wastewater treated by such a method is discharged to rivers and the like after desalination.
[0004]
[Problems to be solved by the invention]
As described above, in the method of performing the electrolysis by adding the salt to the waste liquid, since a maximum of 20% of salt is added, it is necessary to provide an electrodialysis tank in a later step for desalting. Therefore, there is a problem that the process becomes complicated and the cost increases.
[0005]
Therefore, an object of the present invention is to provide a water treatment apparatus capable of treating wastewater with high efficiency without removing residual chlorides such as salt.
[0006]
[Means for Solving the Problems]
The water treatment apparatus of the present invention has an electrolysis tank provided with an electrode having a property of generating chlorine in water when energized, a reaction tank provided with a heater for heating water treated by the electrolysis tank, A gas dissolving device for dissolving chlorine gas generated in the decomposition tank into water in the reaction tank.
[0007]
In the water treatment apparatus of the present invention, chlorine is generated in water by introducing wastewater from factories, livestock farms, human waste treatment plants, industrial waste disposal sites, and the like into the electrolysis tank and supplying electricity to the electrodes. As a result, the oxidation treatment with chlorine is performed in the electrolysis tank. At the same time, chlorine gas is generated and collects at the upper part of the electrolysis tank.
[0008]
Then, chlorine gas generated in the electrolysis tank is dissolved in water in the reaction tank by a gas dissolving device to increase the chlorine concentration. Therefore, in the reaction tank, the water treated by the electrolysis tank is further oxidized by the water whose chlorine concentration is increased by the gas dissolving device.
[0009]
Further, in the water treatment apparatus of the present invention, the chlorine-containing water in the reaction tank is heated by the heater, so that the oxidizing action by chlorine is efficiently performed. Therefore, the chlorine contained in the water is completely consumed in the reaction tank. The oxidizing action by chlorine is most efficiently performed at 40 to 60 ° C. Therefore, the heater according to the present invention desirably heats the water in the reaction tank to the temperature of 40 to 60 ° C.
[0010]
Further, the electrode of the electrolysis tank according to the present invention may be one coated with a platinum-based material or a ruthenium-based material. Electrodes coated with platinum-based materials generate chlorine in water. In particular, an electrode coated with a ruthenium-based material generates a high concentration of hypochlorous acid in water, so that a very strong oxidizing action can be obtained.
[0011]
It is desirable that the gas dissolving apparatus according to the present invention further dissolves ozone into water in the reaction tank. By dissolving the ozone together with the chlorine gas in the water of the reaction tank, the ozone reacts with the chlorine, and the oxidizing action of each other is increased three to four times by a synergistic effect.
[0012]
In the electrolysis tank, chlorine gas bubbles are constantly generated from the cathode and the anode, and the bubbles cause floating substances in the water to become oxides and float as scum near the water surface. Therefore, it is desirable that the water treatment apparatus of the present invention is provided with a means for continuously scraping the vicinity of the water surface of the electrolysis tank with the fins. Thus, the scum can be continuously scraped off by the fins and discharged.
[0013]
Further, it is desirable that the water treatment apparatus of the present invention is provided with a gas vent valve for discharging gas through an activated carbon filter above the reaction tank. This makes it possible to decompose the trace amount of chlorine gas that floats after being used for the reaction in the reaction tank, remove odor components, and safely discharge the chlorine gas.
[0014]
Further, the water treatment apparatus of the present invention is preferably provided with a heat exchanger for performing heat exchange between the treated water discharge port of the reaction tank and the raw water introduction port of the electrolysis tank. As a result, the temperature of the water heated by the heater in the reaction tank can be lowered and discharged from the treated water outlet, and the temperature of the water introduced into the electrolysis tank can be raised to increase the chlorine generated in the electrolysis tank. The oxidizing action by the oxidizing agent.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 is a plan view showing a schematic configuration of a water treatment apparatus according to an embodiment of the present invention, and FIG. 2 is a schematic view showing a vertical section of the electrolysis tank of FIG.
[0016]
As shown in FIG. 1, a water treatment apparatus according to the present embodiment includes an electrolysis tank 10 in which a pair of cathode plates 11a and an anode plate 11b are alternately arranged, a reaction tank 20 in which a heater 21 is provided, and a reaction tank 20. The apparatus includes a gas dissolving device 30 that circulates water in the tank 20 to dissolve chlorine gas taken out of the electrolysis tank 10, and a scum discharge tank 40 that discharges scum floating near the water surface of the electrolysis tank 10.
[0017]
The cathode plate 11a and the anode plate 11b of the electrolysis tank 10 are metal electrodes formed by thermally decomposing (firing) a coating layer of a ruthenium-based material on a titanium substrate. Here, the ruthenium-based material is a material containing ruthenium (Ru), and includes pure ruthenium and a composite material in which ruthenium is blended with platinum or another material. Further, a material coated on a metal substrate other than titanium can also be used.
[0018]
As shown in FIG. 2, an unsupported annular belt 13 having a plurality of fins 12 at predetermined intervals is disposed above the electrolysis tank 10. The fins 12 are formed of an elastic rubber plate or the like. The fins 12 continuously advance as if scraping near the water surface of the electrolysis tank 10 by the rotation of the unsupported annular belt 13, and scrape the floating material (scum) near the water surface to the scum discharge tank 40.
[0019]
In addition, a gas pipe 14 that leads the chlorine gas collected at the upper part of the electrolysis tank 10 to the gas dissolving device 30 is connected to the upper surface of the electrolysis tank 10.
[0020]
Returning to FIG. 1, a heater 21 provided in the reaction tank 20 is an electrode heater for heating water in the reaction tank 20. The heater 21 is controlled such that the water temperature is constantly maintained at 40 to 60 ° C. based on the detection result of the water temperature by a temperature sensor (not shown) provided in the reaction tank 20. Further, a gas vent valve (not shown) for discharging gas through an activated carbon filter is provided at an upper portion of the reaction tank 20.
[0021]
The gas dissolving device 30 is for dissolving the chlorine gas introduced from the electrolysis tank 10 by the gas pipe 14 in water taken in from the reaction tank 20 and returning the chlorine gas to the reaction tank 20. As the gas dissolving apparatus 30, for example, a gas-liquid mixing apparatus which the present inventor himself applied for and published internationally under International Publication No. WO99 / 33552 can be used.
[0022]
In the water treatment apparatus having the above-described configuration, wastewater (hereinafter, referred to as “raw water”) from a factory, a livestock farm, a human waste treatment plant, an industrial waste disposal site, or the like is fed from a raw water inlet 16 below the electrolysis tank 10 to the Introduce into 10. These raw waters generally have high electrical conductivity because they contain salt, but in the case of raw water that does not contain salt, chloride is introduced to increase the electrical conductivity of the water.
[0023]
In the electrolysis tank 10, the raw water is electrolyzed by energizing the cathode plate 11a and the anode plate 11b, and chlorine is generated in the water. In particular, in the present embodiment, since metal electrodes coated with a ruthenium-based material are used for the cathode plate 11a and the anode plate 11b, a high concentration of hypochlorite having a strong oxidizing action from these electrodes by electrolysis. Generates acids. This aqueous solution of hypochlorous acid is unstable and produces hydrochloric acid, oxygen and chloric acid. In the electrolysis tank 10, the decolorization and deodorization of the raw water are performed by the strong oxidizing action of the high-concentration hypochlorous acid, and the solubility COD (chemical oxygen demand) is also greatly improved. In addition, in the electrolysis tank 10, since salt in water is used for the generation of hypochlorous acid, desalination of raw water is performed at the same time.
[0024]
In addition, in the electrolysis tank 10, a flocculation action occurs due to electrolysis, and bubbles (chlorine gas) are constantly generated from the cathode plate 11 a and the anode plate 11 b by electrolysis. The generated flocks float as scum S near the water surface due to the bubbles. In addition, the suspended matter contained in the water becomes an oxide due to the bubbles, and floats as scum S near the water surface. The scum S floating near the water surface is scraped out to the scum discharge tank 40 by the fins 12 of the rotating unsupported annular belt 13 and discharged from the discharge port 41 of the scum discharge tank 40. As a result, the water in the electrolysis tank 10 has a low SS (floating substance amount), and the COD and the BOD (biochemical oxygen demand) are low and improved.
[0025]
The water that has been decolorized, deodorized, and desalted by electrolysis in the electrolysis tank 10 is introduced into the reaction tank 20 from the treated water communication port 17 in the upper part of the electrolysis tank 10. On the other hand, chlorine gas generated in the electrolysis tank 10 is dissolved in the water in the reaction tank 20 by the gas dissolving device 30. The chlorine dissolved by the gas dissolving device 30 exerts a very high oxidizing effect because the water in the reaction tank 20 is constantly maintained at 40 to 60 ° C. by the heater 21, and the decoloring / deodorizing effect is obtained. As it increases, a bactericidal action occurs.
[0026]
Thus, the water that has been decolorized, deodorized, and desalinated by electrolysis in the electrolysis tank 10 is further decolorized, deodorized, and sterilized in the reaction tank 20, and is discharged as treated water from the treated water discharge port 23. Here, the chlorine gas generated in the electrolysis tank 10 and the chlorine contained in the raw water are all used for the oxidizing action in the reaction tank 20 and are completely consumed in the reaction tank 20. The treated water discharged from the water discharge port 23 contains no chlorine.
[0027]
In addition, by using the gas dissolving device 30 in the present embodiment to further dissolve ozone in the water of the reaction tank 20, the oxidizing action in the reaction tank 20 can be increased three to four times. This is because by dissolving the ozone together with the chlorine gas in the water of the reaction tank, the ozone reacts with the chlorine, and the mutual oxidizing action is enhanced by a synergistic effect.
[0028]
Further, in the present embodiment, when a trace amount of chlorine gas floating after being used for the reaction is accumulated in the upper part of the reaction tank 20, the gas is released from the gas release valve provided in the upper part of the reaction tank 20 through the activated carbon filter. Discharge. Thereby, the gas discharged from the vent valve is one in which the chlorine content is decomposed by the activated carbon filter and the odor component is removed, thereby enhancing safety.
[0029]
Further, the water treatment apparatus of the present embodiment may be configured to include a heat exchanger that exchanges heat between the treated water outlet 23 of the reaction tank 20 and the raw water inlet 16 of the electrolysis tank 10. . Thereby, the temperature of the water heated by the heater 21 in the reaction tank 20 can be lowered and discharged from the treated water outlet 23, so that the influence of the temperature rise on the environment for discharging the treated water can be reduced. Can be. Further, since the temperature of the water introduced from the raw water inlet 16 to the electrolysis tank 10 can be increased by this heat exchange, the oxidizing effect of chlorine generated in the electrolysis tank 10 can be further enhanced.
[0030]
In this embodiment, the cathode plate 11a and the anode plate 11b of the electrolysis tank 10 are all coated with a ruthenium-based material, but a part of the cathode plate 11a and the anode plate 11b is replaced with an iron electrode. Is also effective. With such a configuration, iron is eluted by electrolysis of the iron electrode, and phosphorus and nitrogen in water due to the eluted iron can be aggregated and removed.
[0031]
If the water introduced from the raw water inlet 16 is a reducing waste liquid (anoxic state) or a waste liquid containing sulfide, iron sulfide may be generated due to iron agglomeration and the dye may remain. In this case, the sulfide can be oxidized by dissolving ozone in the water in the reaction tank 20 as described above, but the initial cost may increase.
[0032]
Therefore, in this case, it is preferable that a part of the cathode plate 11a and the anode plate 11b of the electrolysis tank 10 be a metal electrode in which a coating layer of an iridium dioxide-based material is further formed on a titanium substrate by thermal decomposition (firing). Here, the iridium dioxide-based material is a material mainly composed of iridium dioxide, and includes only iridium dioxide and a composite material in which iridium dioxide is blended with another material.
[0033]
Thus, the metal electrode coated with the iridium dioxide-based material generates oxygen in water by electrolysis. By the generated oxygen, sulfide generated by iron coagulation can be oxidized in the electrolysis tank 10. Thereby, since the pretreatment of the oxidation treatment with ozone in the reaction tank 20 can be performed, the required amount of ozone in the reaction tank 20 can be reduced, and the initial cost of the apparatus can be reduced.
[0034]
In the water treatment apparatus according to the present embodiment, water in which chlorine gas or ozone is dissolved by the gas dissolving device 30 is introduced into the raw water inlet 16 of the electrolysis tank 10, and is further electrolyzed in the electrolysis tank 10. It is also effective to adopt a configuration in which water is led to the gas dissolving device 30 and circulated. As described above, by mixing the raw water with water in which chlorine gas or ozone is dissolved and then introducing the mixed water into the electrolysis tank 10, the oxidizing action in the electrolysis tank 10 can be further enhanced.
[0035]
【The invention's effect】
According to the present invention, the following effects can be obtained.
[0036]
(1) An electrolysis tank provided with an electrode having the property of generating chlorine in water when energized, a reaction tank provided with a heater for heating water treated by the electrolysis tank, and an electrolysis tank. With a gas dissolving device that dissolves chlorine gas in the water of the reaction tank, decolorization and deodorization are achieved by electrolysis, and chlorine generated by electrolysis is dissolved in water and heated to decolorize, deodorize, and sterilize. It can be performed. Further, since all the chlorine is consumed in the oxidation treatment by heating, the treated water does not contain the chlorine, and the removal of the chlorine from the treated water becomes unnecessary. Thereby, in the water treatment apparatus of the present invention, a larger water treatment effect can be obtained with a smaller electrode and a smaller amount of power than the conventional water treatment apparatus, and the running cost of the apparatus can be reduced while reducing the cost of the apparatus itself. .
[0037]
(2) Since suspended matter contained in water can be floated as oxide by bubbles of chlorine gas generated from the electrode, SS (suspended substance amount), COD (chemical oxygen demand) and BOD (biochemical Oxygen demand) can be improved. The floating oxide can be continuously scraped and discharged by the fins provided near the water surface of the electrolysis tank.
[0038]
(3) Since the gas dissolving device further dissolves ozone into water in the reaction tank, the oxidizing action in the reaction tank can be enhanced, and a higher water treatment effect can be obtained.
[0039]
(4) Equipped with a gas vent valve at the top of the reaction tank to discharge gas through an activated carbon filter, it decomposes the trace amount of chlorine gas that floated after being used for the reaction in the reaction tank and reduced odor components. It can be removed and safely discharged.
[0040]
(5) By providing a heat exchanger for performing heat exchange between the treated water outlet of the reaction tank and the raw water inlet of the electrolysis tank, the temperature of the water heated by the heater in the reaction tank is reduced. The water can be discharged from the treated water discharge port, and the temperature of the water introduced into the electrolysis tank can be increased to increase the oxidizing effect of chlorine generated in the electrolysis tank. Thereby, the influence of the temperature rise on the environment for discharging the treated water can be reduced, and a higher water treatment effect can be obtained.
[Brief description of the drawings]
FIG. 1 is a plan view showing a schematic configuration of a water treatment apparatus according to an embodiment of the present invention.
FIG. 2 is a schematic view showing a vertical cross section of the electrolysis tank of FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Electrolysis tank 11a Cathode plate 11b Anode plate 12 Fins 13 Unsupported annular belt 14 Gas pipe 16 Raw water inlet 17 Treated water communication port 20 Reaction tank 21 Heater 22 Activated carbon 23 Treated water discharge port 30 Gas dissolving device 40 Scum Discharge tank 41 Discharge port S Scum

Claims (7)

An electrolysis tank provided with an electrode having a property of generating chlorine in water when energized, a reaction tank provided with a heater for heating water treated by the electrolysis tank, and chlorine gas generated in the electrolysis tank And a gas dissolving device for dissolving the compound in water of the reaction tank. The water treatment device according to claim 1, wherein the electrode is coated with a platinum-based material or a ruthenium-based material. The water treatment device according to claim 1, wherein the heater heats the water to 40 to 60 ° C. 4. The water treatment apparatus according to any one of claims 1 to 3, wherein the gas dissolution apparatus further dissolves ozone into water in the reaction tank. The water treatment apparatus according to any one of claims 1 to 4, further comprising a means for continuously scratching the vicinity of the water surface of the electrolysis tank with a fin. The water treatment apparatus according to any one of claims 1 to 5, further comprising a gas vent valve for discharging gas through an activated carbon filter at an upper part of the reaction tank. The water treatment apparatus according to any one of claims 1 to 6, further comprising a heat exchanger that performs heat exchange between a treated water outlet of the reaction tank and a raw water inlet of the electrolysis tank.

Images