JPH029877B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a water treatment device that can obtain high removal efficiency for many types of pollutants. (Prior Art) Conventionally, a sewage treatment apparatus shown in FIG. 8 has been proposed (Japanese Patent Laid-Open No. 59-87093). This treatment device has a treatment tank 9 formed of an insulating material, with a wastewater inflow pipe 93 connected to the lower part and a purified water outflow pipe 95 connected to the upper part, and a large number of holes 94 in the treatment tank.
Two electrode plates 91 and 92 with open electrodes 91 and 92 are arranged above and below with an interval between them, and the lower electrode plate is energized so that it becomes a positive electrode and the upper electrode plate becomes a negative electrode. The electrolytic chamber is filled with a large number of spherical fillers 90 made of a soluble metal with a high tendency to ionize, for example an aluminum alloy. The treatment tank 9 is supplied with wastewater to which an additive for promoting the reaction, such as aluminum chloride, is added from an inflow pipe 93 . This dirty water passes through the lower electrode plate 92, flows into the electrolytic chamber, and rises therebetween while contacting the filler 90. When the wastewater passes between the fillers 90 and rises, various pollutants in the wastewater undergo an electrolytic reaction, are decomposed and precipitated. On the other hand, metal ions are eluted from the surface of the filler 90 and react with chlorine ions and the like in the wastewater to generate aluminum hydroxide. The aluminum hydroxide forms a covalent bond, adsorption, inclusion, etc. with the precipitate, and gradually forms an insoluble floc. Furthermore, these flocs adsorb hydrogen gas generated on the cathode side and oxygen gas generated on the anode side, so that their apparent specific gravity becomes smaller and they float to the top of the processing tank 9. The pollutants that float to the surface in the form of flocs (hereinafter referred to as scum) form a two-layer flow with water and flow through the outflow pipe 9.
5, and is supplied to a well-known flotation separation layer (not shown), where scum is removed. In addition, the above-mentioned device is capable of reducing the oxidation reaction that occurs when wastewater passes through the positive electrode plate 91 and the negative electrode plate 92.
The reduction reaction that occurs when passing through the water transforms pollutants into harmless and stable substances, reducing BOD,
It also reduces COD etc. (Problem to be solved) However, in the above-mentioned sewage treatment equipment, the removal rate is low depending on the type of pollutant contained in the sewage, and it is difficult to treat sewage containing many types of pollutants. However, there was a problem that sufficient removal efficiency could not be obtained. (Means for solving the problem) The inventor has repeatedly conducted various experiments in order to solve the above problem, and as a result, it has been found that separating electrolytic oxidation and electrolytic reduction is extremely effective in improving removal efficiency. They investigated this and completed the present invention. The electrochemical reactions that occur in the water treatment equipment of the present invention are extremely complex, and a complete theoretical explanation is currently not possible. However, according to experiments and analyzes conducted by the inventor, the following It is inferred as follows. That is, when there are a wide variety of pollutants in wastewater, it is impossible to remove them with a single purification process, but in the water treatment device according to the present invention, neutralization, oxidation, reduction, It is thought that each of the aggregation processes is carried out effectively, and that the chemical changes accompanying these processes mutually influence each other, resulting in an effect greater than the sum of the effects of each process. In the sewage treatment equipment according to the present invention, an even number of treatment tanks with insulated inner surfaces are arranged in parallel, and the upper part of the treatment tank on the upstream side and the bottom part on the downstream side are connected to each other, and the lower part of the most upstream treatment tank is connected to the bottom part of the treatment tank. A purified water outlet was installed at the inlet and at the top of the most downstream treatment tank. In each treatment tank, an odd number of water-permeable electrode plates are arranged vertically at intervals, and adjacent electrode plates have different polarities, and the uppermost electrode plate in the upstream tank and the lowermost electrode plate in the downstream tank. Electrify so that the polarity is different from that of the electrode plate. In addition, each electrolytic chamber formed between the electrode plates was filled with soluble metal pieces with a porous oxide film on the surface, and numerous gaps were formed between the metal pieces through which the treated water passed. . (Function) After the wastewater to be treated is added with an appropriate additive to promote the reaction, it flows into the equipment from the inlet provided in the most upstream treatment tank, and then flows into the most downstream treatment tank. It passes through each treatment tank in sequence, undergoes electrochemical treatment, and is finally discharged from an outlet provided in the most downstream treatment tank. In each treatment tank, wastewater is sent from the bottom,
It passes through the bottom electrode plate and flows into the first electrolytic chamber, then passes through the upper electrode plate, the electrolytic chamber, and the top electrode plate, and then is sent to the bottom of the processing tank on the downstream side. Ru. A porous hydroxide film is formed on the surface of the soluble metal piece, and the hydroxide film itself has electrical insulation properties in a dry state. However, in water, adjacent metal pieces are separated from each other by a hydroxide film, but since this film is porous, water that has penetrated through the film can pass through the metal pieces, which is equivalent to the electrical resistance of the water. They are electrically connected to each other at a resistance value of . Therefore, when each electrode plate is energized, the metal pieces filled in each electrolytic chamber are charged according to the resistance value,
Inside the electrolytic chamber, a potential distribution that changes from the bottom to the top occurs. As a result, metal ions are eluted from each metal piece at an ion concentration corresponding to each potential portion. The wastewater supplied into each electrolytic chamber passes through the above-mentioned potential distribution, and during this time, various pollutants in the wastewater undergo electrolytic reactions at respective potential parts, and are decomposed and precipitated. The various pollutants precipitated are
Each metal ion has a unique amount of charge, but metal ions with an ion concentration corresponding to the amount of charge are adsorbed on the surface, which neutralizes the surface charge of most pollutants. As a result, countless metal hydroxide particles are generated. The metal hydroxide particles easily combine by collision with each other, and flocculation progresses sequentially. Furthermore, these flocs adsorb hydrogen gas generated on the cathode side and oxygen gas generated on the anode side, reducing their apparent specific gravity and floating to the top of the processing tank. In addition, there is a space between each metal piece that allows the treated water to pass through.
are formed, so the flocs pass through these spaces without difficulty, ascend each electrolytic chamber one after another, and float to the top of the processing tank. Each treatment tank is equipped with an odd number of electrode plates with different polarities, forming an even number of electrolytic chambers.
The sewage in each treatment tank undergoes repeated oxidation and reduction as it passes through these electrode plates, and by the time it passes through the top electrode plate, it is either in an oxidized state or a reduced state. It's summery. As wastewater progresses from the upstream treatment tank to the downstream treatment tank, it goes through the oxidation state and reduction state the same number of times, and finally converges to a neutralized state when it exits the most downstream treatment tank. It turns out. Therefore, in each treatment tank, reactions mainly based on oxidation or reduction occur separately, and the unique pollutants involved in these reactions proceed from the most upstream treatment tank to the most downstream treatment tank. As time passes, the pollutants are decomposed and removed step by step, and in the end, many types of pollutants are removed. (Effects of the Invention) In the water treatment apparatus according to the present invention, since the reaction tank mainly for oxidation and the treatment tank mainly for reduction are separated, each of neutralization, oxidation, reduction, and flocculation Not only are the effects of each purification process effectively exhibited, but these effects work together to provide excellent performance. Therefore, compared to conventional devices, wastewater containing a wide variety of pollutants can be treated with high removal efficiency. (Example) FIGS. 1 and 2 show an example of a sewage treatment apparatus according to the present invention. By partitioning the vertically rectangular parallelepiped-shaped outer tank 2 with a partition wall 20, a first processing chamber 21 and a second processing chamber 22, which serve as an upstream processing tank and a downstream processing tank, respectively, are formed. A first inflow chamber 24 and a second inflow chamber 25 are formed. Further, a scum storage chamber 23 is formed in the upper part of the outer tank 2 adjacent to both processing chambers 21 and 22, and a scum discharge port 73 is provided at the bottom thereof. An outlet 61 provided above the first reaction tank 3 of the first processing chamber 21 and an inlet 62 provided below the second processing chamber 22 are connected by a connecting pipe 6, and the first processing chamber 21 and the second processing chamber 22 are in communication with each other. An inflow pipe 71 is connected to the inflow port 7 to the first inflow chamber 24 , and an outflow port 70 is opened above the second reaction tank 4 in the second processing chamber 22 . Further, a first outlet chamber 75 and a second outlet chamber 76 are formed in communication with the outlet 70, and a triangular weir 74 for adjusting the water level of the outer tank 2 is provided on the partition wall of both the outlet chambers 75, 76. It is equipped to be adjustable in position, and an outflow pipe 72 is connected to the bottom of the second outlet chamber 76 . A well-known scum removing device 8 driven by a motor 83 is disposed above the outer tank 2 .
This device has a plurality of scraping plates 80 fixed to endless chains 81, 81 stretched between a pair of drive rollers 82, 82, as shown in FIGS. 3 and 4. A pair of first reaction tanks 3, 3 and a pair of second reaction tanks 4, 4 are installed in the first processing chamber 21 and the second processing chamber 22, respectively, and both the first reaction tanks 3, 3 are connected to the first inflow chamber 22.
In addition, both second reaction vessels 4, 4 communicate with a second inflow chamber 25. The first reaction tank 3 and the second reaction tank 4 each have first electrode plates 31, 41 and second electrode plates 32, 42 inside a cylindrical body made of an insulating material such as vinyl chloride or FRP. and third electrode plates 33, 43 are fixed at intervals. Each electrode plate has a large number of through holes 34, 44 passing through it vertically. Each of the reaction vessels 3 and 4 has an outer diameter of 280 x 330 mm and a height of 650 mm. Each electrode plate is a carbon electrode such as graphite, and has a thickness of 20 mm and a size of 250 x 300 mm.
The inner diameter of the through hole is 20 mm, and the distance between adjacent electrode plates is
It is 250mm. Further, the number of through holes 34, 44 is 42 per electrode plate. A large number of pipe pieces 5 are filled in the electrolytic chamber formed between each electrode plate. The pipe piece 5 is the fifth
As shown in FIG. 6 and FIG. 6, three through holes 51 are provided in upper and lower two stages at an interval of 120 degrees around the central hole 50, and the surface is covered with porous hydroxide as described below. A film is formed. Each pipe piece 5
The outer diameter D of the center hole 50 is 40 mm, the inner diameter C of the central hole 50 is 10 mm, the height H is 50 mm, the inner diameter B of the through hole 51 is 6 mm, and the distance A from one end of the pipe to the center of the through hole 51 is 15 mm.
It is. Most of the pipe pieces 5 are made of aluminum alloy, and 2 to 5% of the pipe pieces 5 are made of iron alloy. The metal composition of the aluminum alloy pipe piece is Fe: 5.0%, Mg: 4.5
%, Ni: 1.0%, Cr: 0.25%, Zn: 0.25%, Cu:
0.2%, balance Al. On the other hand, the metal components of the iron alloy pipe piece are Ni: 1.6%, Mn: 0.9%, Cr: 0.6
%, C: 0.35%, Si: 0.35%, Mo: 0.3%, P:
0.01%, S: 0.01%, balance Fe. The aluminum alloy pipe piece 5 is immersed in a calcium hydroxide aqueous solution adjusted to pH 11 for 100 hours to form a hydroxide film with a thickness of about 10 μm on the surface. As is well known, the hydroxide film is porous (porous layer) and can contain water. Therefore, a large number of pipe pieces 5 that are in contact with each other in water are electrically connected to each other through the water-containing hydroxide film, and at the same time, metal ions can be eluted into the water through the hydroxide film. It is. The hydroxide film has Al, Mg, and Ca as main components (approximately 90%), and also contains small amounts of each of Fe, Ni, Cr, etc. The first electrode plate 31 and the third electrode plate 33 of the first reaction tank 3 are energized so that they are positive electrodes, and the second electrode plate 32 is a negative electrode. 43 is a negative electrode, and the second electrode plate 42 is energized so that it becomes a positive electrode. The potential difference between adjacent electrode plates is set to a low voltage of about 20V, for example. Therefore, no intense electrolysis of water occurs within the electrolysis chamber. Appropriate additives, such as aluminum sulfate, sodium chloride, calcium hydroxide, etc., are added in advance to the wastewater in an amount of 5 to 20 ppm, and the wastewater is supplied to the first inflow chamber 24 from the inflow pipe 71 of the sewage treatment apparatus 1. The wastewater supplied to the first inflow chamber 24 first flows into the first inflow chamber 24.
After flowing into the reaction tank 3 and undergoing primary treatment mainly consisting of oxidation, it flows into the connecting pipe 6 and the second inflow chamber 25.
It flows into the second reaction tank 4, where it is subjected to a secondary treatment mainly consisting of reduction. The purified water that has been subjected to these treatments first flows into the first outlet chamber 70 from the outlet 70, further flows into the second outlet chamber 72 via the triangular weir 74, and flows out from the outflow pipe 72 to the outside of the apparatus. . In the first reaction tank 3, the wastewater is
When passing through the electrode plates 31, 32, and 33, it is sequentially oxidized, reduced, and oxidized alternately, and when it passes through the third electrode plate 33, it is in an oxidized state. During this time, decomposition of the pollutants occurs, and chlorine ions contained in the waste water combine with free oxygen, which becomes an oxidizing agent and reacts with the surface of the pipe piece 5. As a result, aluminum hydroxide and iron hydroxide are produced, and these are supplied to the wastewater. Further, hydrogen gas is generated from the surface of the second electrode plate 32, which is the cathode, and oxygen gas is generated from the surfaces of the first electrode plate 31 and the third electrode plate 33, which are the anodes. Rise and rise. The rising speed of the bubbles is approximately 1.5 to 4 cm/sec, and these rising bubbles generate convection within the electrolytic chamber, which promotes the formation of pollutants into flocs.
The rising air bubbles adsorb this floc and float it to the upper part of the processing chamber 21. At this time, a large number of pipe pieces 5 are filled in the electrolytic chamber in random positions, but countless gaps are created between each pipe piece, and each pipe piece is connected to the central hole 50 and the peripheral wall. Since it has six through holes 51, the flocs pass through these holes without difficulty, ascend each electrolytic chamber one by one, and float to the top of the processing layer. These flocs therefore do not build up between the pipe pieces. Next, in the second reaction tank 4, the wastewater is mixed with the first
When passing through the third electrode plates 41, 42, and 43, it is sequentially subjected to the effects of reduction, oxidation, and reduction, and when it initially flows from the first reaction tank 3 to the second inflow chamber 25, it is in an acidic state. When the liquid passes through the third electrode plate 33, it returns to a neutralized state. During this time, different types of pollutants from those in the first reaction tank 3 are decomposed, and these become flocs and float to the upper part of the second processing chamber 22. The process in which the pollutants are decomposed, aggregated, turned into flocs, and floated is the same as in the first processing chamber 21 described above. Note that even if the wastewater supplied to the first reaction tank 3 is biased toward acidity or alkalinity, the wastewater must pass through each electrode plate in the first reaction tank 3 and the second reaction tank 4 in sequence. As a result, the pH gradually approaches a neutralized state, and by the time it leaves the second reaction tank 4, the pH has converged to approximately 7. As a result, in the first processing chamber 21, a primary treatment mainly consisting of oxidation is performed, and in the second treatment chamber 22, a secondary treatment mainly consisting of reduction is performed. , decomposition and removal of pollutants specific to each type are performed. However, since the aluminum alloy pipe piece 5 introduced into each electrolytic chamber has a large ionization tendency, and the iron alloy pipe piece 5 has a small ionization tendency, the gradient (grad) of the potential between the two electrode plates is It is no longer uniform in the electrolysis chamber,
The voltage varies randomly depending on the position, and as a result, reactions to various pollutants occur at each unique potential gradient. As a result, it is possible to remove more types of contaminants than with the conventional apparatus shown in FIG. The scum floating on the upper part of the first processing chamber 21 and the second processing chamber 22 is moved toward the swash plate 26 provided at the upper end of the outer tank 2 by the movement of the scraping plate 80 of the scum removing device 8. The scum is scraped up and further scraped out from above the swash plate 26 into the scum storage chamber 23 as indicated by the arrow in FIG. 4, and then discharged to the outside through the scum discharge port 73. The inventor constructed a sewage purification system as shown in FIG. 7 using the water treatment device described above, and used the system to purify secondary human waste, cafeteria wastewater, food processing plant wastewater, noodle factory wastewater, and sewage wastewater, respectively. Experiments were conducted to confirm the effects of the water treatment device according to the present invention. However, here, in order to further increase the treatment capacity, two devices shown in FIG. 1 were used as the water treatment device 1, connected in series. This results in a processing capacity of the device of 2 tons/hour. Sewage in the raw water tank 10 is supplied to the water treatment device 1 by a raw water pump 13. Incidentally, a suitable additive is injected into this wastewater from the chemical tank 11 using the chemical injection pump 14. The purified water treated by the water treatment device 1 is further sent to a well-known flotation tank 12, where residual scum in the purified water is completely removed. Some of the results obtained through the experiment are shown in Tables 1 to 5 below. Here, N-Hex represents normal hexane, T-N represents total nitrogen, and T-P represents total phosphorus.

【table】

【table】

【table】

【table】

[Table] A removal rate close to 100% has been achieved for COD, BOD, SS, and other contained components in various types of wastewater. In addition, it can be seen that effects such as deodorization, decolorization, and sterilization are also obtained. The conventional apparatus shown in FIG. 8 not only has low processing efficiency, but also has the problem that flocs tend to accumulate between the spherical fillers 90, making continuous operation impossible. On the other hand, in the water treatment device according to the present invention, the soluble metal pieces are composed of pipe pieces having a plurality of through holes, so the effective surface area per unit weight is large, and these pipes have a large effective surface area per unit weight. Sufficient space is formed between the pieces and each pipe piece itself for the treated water containing flocs to pass through.
Continuous operation with high efficiency is possible. Further, as mentioned above, the voltage to be applied to each electrode plate is low, and the current flowing between the electrodes is, for example, about 3A, so power consumption is extremely low. Moreover, since it can purify many types of wastewater more efficiently than conventional devices, it is also extremely effective as a household water treatment device. It goes without saying that the configuration of each part of the present invention is not limited to the above-mentioned embodiments, and various modifications can be made within the technical scope of the claims. For example, the effluent from the scum storage chamber 23 shown in FIGS. 1 and 2 contains a small amount of the additives added to the treated water, so after separating the scum from the effluent, This is further connected to the inflow pipe 71
It is possible to effectively utilize the additive by supplying it into the device from the source. The polarity of the voltage to be applied to each electrode plate in Figure 1 is
It is possible to have the positive and negative values reversed. In addition, the number of electrode plates to be arranged in each processing tank is not limited to three stages, but may be five or more odd number stages, and furthermore, the number of processing tanks to be arranged in parallel is not limited to two rows but four rows. Or it may be an even number sequence. Furthermore, the metal pieces to be filled in each electrolytic chamber are as follows:
The pipe piece is not limited to the above-mentioned pipe piece, but may be, for example, a tetrapod-shaped piece.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view schematically showing a water treatment device according to the present invention, FIG. 2 is a cross-sectional view taken along the line - FIG.
Fig. 3 is a perspective view showing the main parts of the scum removal device, Fig. 4 is a sectional view of the scum storage chamber, Figs. 5 and 6 are a partially cutaway side view and plan view of a pipe piece, respectively, and Fig. 7 8 is a schematic diagram of a sewage purification system using the water treatment device according to the present invention, and FIG. 8 is a sectional view of a conventional device. 21...First processing chamber, 22...Second processing chamber, 3
...First reaction tank, 4...Second reaction tank, 31, 41
...First electrode plate, 32, 42...Second electrode plate, 3
3, 43...Third electrode plate, 5...Pipe piece, 6...
...Connecting pipe, 7...Inflow port, 70...Outflow port, 8...
...Scum elimination device.

Claims (1)

[Claims] 1. An even number of processing tanks with insulated inner surfaces are arranged in parallel,
The upper part of the upstream treatment tank and the bottom part of the downstream treatment tank are connected to each other, an inlet is provided at the bottom of the most upstream treatment tank, and an outlet is provided at the upper part of the most downstream treatment tank, and in each treatment tank, An odd number of water-permeable electrode plates are arranged vertically at intervals, and adjacent electrode plates have different polarities, and the uppermost electrode plate of the upstream processing tank and the lowermost electrode plate of the downstream processing tank Electricity is applied so that the polarity is different from that of the electrode plates, and each electrolytic chamber formed between the electrode plates is filled with a large number of soluble metal pieces with porous hydroxide films formed on the surface. In the water treatment equipment, a large number of holes are formed through which the treated water passes. 2 The processing tank includes a first processing chamber 21 and a second processing chamber 2 formed inside a vertically long outer tank 2 with a partition wall 20 separated.
The first processing tank of the first processing chamber 21 consists of an upstream processing tank and a downstream processing tank configured by installing first and second reaction tanks 3 and 30 each equipped with three stages of electrode plates at the bottom of the first processing chamber 21. 3, an inlet 7 is provided below, and an outlet 70 is provided above the second processing tank 4 of the second processing chamber 22. The water treatment device according to claim 1, wherein the lower part of the tank 4 is connected to the lower part of the tank 4 by a connecting pipe 6. 3. The water treatment device according to claim 1 or 2, wherein the soluble metal piece is a pipe piece 5. 4. The water treatment device according to claim 3, wherein the pipe piece 5 has a plurality of through holes on its circumferential surface. 5. The water treatment device according to claim 4, wherein each electrolysis chamber is filled with a mixture of a large number of aluminum alloy pipe pieces and a small number of iron alloy pipe pieces.