JPH0839075A - Method and equipment for treating sewage - Google Patents

Abstract

PURPOSE:To reduce an installation area, to minimize the injection amt. of chemicals and to reduce equipment cost or running cost while reducing maintenance labor. CONSTITUTION:Sewage is subjected to electrolytic precipitation treatment in a non-diaphragm electrolytic cell 46 to flocculate and precipitate the ionized matter or suspended matter dissolved in sewage and the matter flocculated and precipitated in the non-diaphragm electrolytic cell 46 is filtered off by a filter 50 and the treated water of the filter 50 is neutralized in a carbon dioxide mixer 51 by the injection of carbon dioxide and electric energy is applied to the neutralized treated water in an AC voltage type water treatment device 57 to prevent the growth of scale matter such as a calcium ion, a magnesium ion or silica dissolved in the treated water.

Description

Detailed Description of the Invention

[0001]

[Field of Industrial Application] The present invention is sewage for treating leachate from a final disposal site (landfill) for wastes, plant wastewater discharged from an intermediate treatment facility, car wash wastewater, and domestic wastewater. The present invention relates to a treatment method and its equipment.

[0002]

2. Description of the Related Art Conventionally, for example, at a final disposal site (landfill) for waste, etc., wastewater is treated using the equipment shown in FIG.

That is, the rainwater that has fallen to the final disposal site 1 (landfill) for wastes passes between the landfills and goes to the water collection pit 2 through the water collection pipe (not shown) attached to the bottom of the disposal site 1. Be flowed in.

The sewage that has flowed into the water collecting pit 2 is pumped up by a water intake pump (not shown) provided in the water collecting pit 2 and temporarily stored in the regulating pond 3 so that the amount of water and the quality of the water are made uniform.

The regulating pond 3 is made larger in consideration of a large amount of inflowing sewage, especially during a typhoon season, so that the storage capacity can be adjusted.

Further, in order to keep the sewage rich and prevent the sedimentation of suspended matter, aeration and agitation by an aerator (not shown) is performed.

The sewage collected in the regulating basin 3 is sent to the leachate receiving tank 4 by a leachate pressure pump (not shown), and the sewage sent to the leachate receiving tank 4 is measured by a not-shown sewage measuring tank while the sand settling tank is being measured. 5, the sand is removed from the wastewater in the sand settling tank 5.

The wastewater from which sand and the like has been removed by sedimentation in the sand settling tank 5 is
It is sent to the pH adjusting tank 6, and the pH of the waste water is adjusted in the pH adjusting tank 6 for the subsequent microbial treatment step.

The above is the pretreatment step 7 for sewage.

Then, the sewage whose pH has been adjusted in the pH adjusting tank 6 is then sent to the oxidizing tank 8 and passed through the filter medium in the oxidizing tank 8 to come into contact with the microorganisms adhering to the filter medium, and the sewage The organic matter dissolved in is adsorbed and decomposed.

Since the microorganisms in the oxidation tank 8 are aerobic and require oxygen, air agitation is performed by using an aeration blower (not shown) so that the aerobic microorganisms adhering to the wastewater and the contact filter medium are aerated. Oxygen is supplied at the same time as the contact with is promoted.

Further, in the oxidizing tank 8, the phosphorus content in the wastewater tends to be insufficient due to the activity of the microorganisms, so that phosphoric acid is injected as a nutrient for the microorganisms, if necessary.

The sewage whose organic substances have been decomposed by the microorganisms in the oxidation tank 8 is sent to a settling tank 9 where it is separated into sludge and supernatant sewage.

The sludge that has settled is scraped to the center of the settling tank 9 by using a sludge scraper (not shown), and is periodically drawn out by a suction pump (not shown) with a predetermined amount left, and then to the sludge thickening tank 10. Sent.

The remaining sludge is reused in the settling tank 9 as seed sludge.

The supernatant sewage separated in the settling tank 9 is sent to the defoaming pump tank 11 and sprayed to the oxidizing tank 8 by a defoaming pump (not shown) provided in the defoaming pump tank 11. It is used for defoaming bubbles generated by the activity of microorganisms in the oxidation tank 8.

Then, the wastewater in the defoaming pump tank 11 is sent to the nitrification tank 12, passed through the filter medium in the nitrification tank 12, and contacted with the nitrifying bacteria adhering to the filter material, so that all the nitrogen components dissolved in the wastewater. Is nitrified into nitrite nitrogen and nitrate nitrogen.

Since nitrifying bacteria are aerobic and require oxygen, agitating air using an aeration blower (not shown) promotes contact between sewage and nitrifying bacteria adhering to the filter medium. At the same time, oxygen is supplied.

Further, since the optimum condition for nitrifying bacteria is pH 7 to 8, caustic soda is injected when the alkalinity of wastewater is low.

The wastewater nitrified in the nitrification tank 12 is treated by the denitrification tank 1
3 to be passed through the filter medium in the denitrification tank 13 and contacted with the denitrifying bacteria adhering to the filter medium to gasify the nitrate nitrogen and nitrite nitrogen dissolved in the sewage into nitrogen gas and release it to the atmosphere. To remove the nitrogen component.

Since the denitrifying bacteria are anaerobic, they are not stirred in air, but only stirred in water by an underwater stirrer.

Further, methanol is injected into the denitrification tank 13 as a nutrient source for denitrifying bacteria.

The sewage denitrified in the denitrification tank 13 is sent to the re-aeration tank 14, and in the re-aeration tank 14, due to aerobic microorganisms,
In the denitrification tank 13, the excessively injected methanol is decomposed and removed, and the remaining methanol is prevented from becoming an organic substance.

The above is the microbial treatment step 15.

The sewage aerated in the re-aeration tank 14 is sent to the mixing tank 16, and the inorganic coagulant such as polyaluminum chloride is added in the mixing tank 16 and then stirred by a stirrer not shown. Agglomerate flocs by aggregating fine suspended matter in wastewater.

The sewage water in which coagulation flocs are generated in the mixing tank 16 is further sent to the coagulation tank 17 and injected into the coagulation tank 17 with a polymer coagulant such as polyacrylamide as an auxiliary agent. Slowly stirs to make the floc larger and harder and harder to break.

The sewage water in which the flocs of flocs are grown in the flocculation tank 17 is sent to the flocculation sedimentation tank 18, and is separated and separated into sludge and supernatant treated water in the flocculation sedimentation tank 18.

The sludge that has settled is scraped to the center of the coagulating sedimentation tank 18 by using a sludge scraper (not shown), and is periodically drawn out by a suction pump (not shown), and the sludge thickening tank 1
Sent to 0.

The treated water from which the sludge has been separated in the coagulation-sedimentation tank 18 is sent to the neutralization tank 19, and the mixing tank 16 and the coagulation tank 17 neutralize the pH change caused by the addition of the coagulant.

The above is the aggregation and precipitation step 20.

The treated water neutralized in the neutralization tank 19 is sent to the raw filtration water tank 21, and is sent from the raw filtration water tank 21 to the sand filtration tower 22 by a pressure pump (not shown).

In the sand filter tower 22, a sludge solid matter which could not be removed by the treatment up to the preceding stage is filtered and removed by a pressure type sand filter (not shown).

The sludge solid matter filtered and removed is regularly backwashed with water and air and returned to the leachate receiving tank 4.

The treated water obtained by filtering the sludge solids in the sand filter tower 22 is stored in the treated water tank 23, and a part of the treated water is stored in the sand filter tower 22.
It is used for back washing.

The above is the filtration step 24.

After that, the treated water in the treated water tank 23 is sent to the disinfecting tank 25, and is disinfected by the disinfectant in the disinfecting tank 25 to reduce the number of coliform bacteria to 3,000 / ml or less.

As the disinfectant, tablets of calcium hypozincate or the like are used, and the disinfectant tank 25 is provided with a container capable of dissolving the tablets in fixed amounts.

In the disinfection tank 25, the treated water is allowed to stay for 15 minutes or more so that the disinfection reaction is sufficiently performed.

The above is the disinfection step 26.

The treated water sterilized in the disinfection tank 25 is then sent to the water quality monitoring tank 27, and the water quality monitoring tank 27
Is discharged from rivers to rivers or reused in plants.

On the other hand, in the sludge thickening tank 10, the sludge drawn out from the settling tanks 9 and 18 is concentrated to reduce the sludge volume.

The sludge reduced in the sludge thickening tank 10 is temporarily stored in the sludge storage tank 28 and supplied to the sludge dehydrator 29 in a fixed amount.

In the sludge thickening tank 10, air is blown in to prevent the stored sludge from spoiling, so that the sludge is kept aerated.

In the sludge dewatering machine 29, a polymer flocculant is injected as a dewatering aid, and the centrifugal dewatering machine further reduces the water content of the sludge to facilitate sludge disposal.

The sludge (dehydrated cake) dewatered in the sludge thickening tank 10 is stored in the cake hopper 30, and is regularly carried out to the outside (landfill) for disposal.

The water dewatered in the sludge treatment step 31 is returned to the leachate receiving tank 4.

[0047]

However, the above-mentioned conventional wastewater treatment method and its equipment have the following problems.

That is, the above conventional coagulation-sedimentation type equipment has a problem that a large number of tanks are required because the process is complicated and, as a result, the installation area of the entire equipment becomes large.

Further, as a coagulant, a polymer coagulant such as polyacrylamide or an inorganic coagulant such as polyaluminum chloride is injected, and an acid such as hydrochloric acid or the like is added for promoting coagulation or neutralization. Since alkali such as caustic soda is injected, there are problems that a large amount of chemicals is used and that separate safety measures are required against excessive injection of chemicals.

[0050] Further, the equipment cost and running cost are increased due to the above, and it is not sufficient in terms of maintenance.

In view of the above situation, it is an object of the present invention to provide a sewage treatment method and a facility therefor which can reduce the installation area and minimize the injection amount of chemicals.

[0052]

The method for treating sewage of the present invention is one in which sewage is electrodeposited to coagulate and deposit an ionized product or suspension dissolved in sewage, and the coagulated deposit is removed by filtration. Also, the filtered treated water is neutralized with carbon dioxide gas,
Furthermore, the electric energy is applied to the treated water to inhibit the growth of scales dissolved in the treated water.

The sewage treatment facility of the present invention comprises a diaphragmless electric field tank for electrodepositing sewage to coagulate and deposit the ionized substances and suspensions dissolved in the sewage, and a coagulated precipitate by the diaphragmless electric field tank. And a filter for removing by filtration.
It is equipped with a carbon dioxide mixer that neutralizes the filtered treated water with carbon dioxide, and an AC voltage type water treatment device that applies electrical energy to the treated water and inhibits the growth of scale matters dissolved in the treated water. .

[0054]

The operation of the present invention is as follows.

The sewage is electrodeposited in the diaphragmless electric field tank to cause the ionized substances and suspensions dissolved in the sewage water to coagulate and precipitate, and the coagulated precipitate in the diaphragmless electric field tank is filtered and removed.

After that, the treated water in the filter is neutralized by injecting carbon dioxide gas with a carbon dioxide gas mixer.

Further, electric energy is applied to the treated water neutralized by the AC voltage type water treatment device to inhibit the growth of the scale material dissolved in the treated water.

Therefore, since the electric energy is used for the treatment, the injection amount of the drug can be minimized.

Further, since the equipment structure is simple, the installation area can be reduced, equipment costs and running costs can be reduced, and maintenance work can be reduced.

[0060]

Embodiments of the present invention will be described below with reference to the drawings.

1 to 3 show an embodiment of the present invention.

In the figure, 32 is a final disposal site for waste such as landfills, 33 is a water collecting pit for collecting rainwater, etc. that has fallen to the final disposal site for waste 32, and 34 is a collecting pit 33. A regulating pond for temporarily storing sewage, 35 is a regulating pond 34
It is a settling tank that separates the sewage from sewage into sludge and supernatant sewage.

On the other hand, 36 is an intermediate treatment facility for discharging plant drainage, car wash drainage, domestic drainage and the like, and 37 is a combined aeration septic tank for treating the discharge water from the intermediate treatment facility 36.

38 is a reaction tank for adjusting the pH of the wastewater separated in the settling water receiving tank 35 as required, 39 is an acid tank for storing an acid such as hydrochloric acid, and 40 is an alkali liquid such as sodium hydroxide. An alkali tank, 41 is a pH meter for detecting the pH value of the reaction tank 38, and 45 is hydrochloric acid in the acid tank 39 or sodium hydroxide in the alkali tank 40 is injected into the reaction tank 38 based on the pH value 42 from the pH meter 41. A dosing controller that produces signals 43,44.

Reference numeral 46 is a membraneless electric field tank for electrodepositing the wastewater from the reaction tank 38 to coagulate and deposit the ionized substances and suspensions dissolved in the wastewater, and as shown in FIG. A configuration in which a DC power supply 49 is connected between 47 and 48 is provided.

The diaphragmless electric field tank 46 includes the two electrodes 47, 4
Aluminum is used for both 8 and a DC voltage of about 1 kV is applied. The polarities of the electrodes 47 and 48 are periodically exchanged to prevent the electrodes 47 and 48 from being worn out.

Reference numeral 50 denotes a rapid filter in which a tank is filled with anthracite (a granular material made from anthracite), a filter material such as a ceramic filter or a hollow fiber membrane.

51 is a carbon dioxide gas mixer for neutralizing the lime content dissolved in the treated water that has passed through the rapid filter 50, 52 is a carbon dioxide gas cylinder for storing carbon dioxide gas, and 53 is a pH value 54 of the carbon dioxide gas mixer 51. PH meter, 55 is pH
Based on the pH value 54 from the total 53, the carbon dioxide gas cylinder 52
Signal 5 to inject the carbon dioxide gas of the above into the carbon dioxide mixer 51
It is a carbon dioxide gas controller that generates 6.

Reference numeral 57 denotes an AC voltage type water treatment device which inhibits the growth of scale substances such as calcium ions, magnesium ions and silica dissolved in the treated water by electric energy. As shown in FIG. Of the pair of electrodes 5 along the flow direction of the treated water in the treated main body 58
9, 60 are arranged, and an AC power source 62 for generating a low-voltage AC rectangular wave 61 is connected between the electrodes 59, 60. As the AC power source 62, a power source of about 4 W at 100 V is used.

63 is a flow meter for measuring the flow rate of the treated water discharged from the AC voltage type water treatment device 57, 64 is a disinfectant tank for storing a disinfectant such as sodium hypochlorite, and 65 is a flow meter 63.
In response to the flow rate signal 66 from the AC voltage type water treatment device 57
A disinfectant controller that generates a signal 68 for injecting a disinfectant such as sodium hypochlorite in the middle of the outlet side flow path 67,
69 is a treated water storage tank for temporarily storing the disinfected treated water.

Incidentally, 70 is a sludge storage tank for storing the sludge separated in the settling water receiving tank 35, 71 is a dehydrator for dehydrating the sludge from the sludge storage tank 70, and 72 is sludge dehydrated by the dehydrator 71 (dehydration). It is a cake hopper that stores cake.

Further, 73 is a pump activated by a level switch 74 provided in each tank 35, 38, 46, 69, 75 is an underwater sludge pump for pumping the sludge settled in the settling water receiving tank 35, and 76 is A sludge pump for transferring the sludge in the sludge storage tank 70 to the dehydrator 71, and a coagulant tank 77 for storing the coagulant injected into the sludge sent to the sludge storage tank 70.

78 is each tank 38, 46, 50, 69, 7
A return system for returning the overflow amount of 0, 71, dehydrated water, etc. to the settling water receiving tank 35, 79 a backwashing system for backwashing the filter medium in the rapid filter 50 with the treated water stored in the treated water storage tank 69, 80 is a backwash pump.

Furthermore, the acid tank 39 and the alkali tank 4
0, a carbon dioxide gas cylinder 52, a disinfectant tank 64, and a coagulant tank 77 are provided with flow rate adjusting valves (not shown) at their outlets so that the injection amount can be adjusted.

Next, the operation will be described.

Rainwater that has fallen to the final disposal site 32 (landfill) of wastes passes between the landfills and flows into the water collection pit 33 through a water collection pipe (not shown) attached to the bottom of the landfill site 32. It

The sewage that has flowed into the water collecting pit 33 is pumped up by a water intake pump (not shown) provided in the water collecting pit 33 and temporarily stored in the regulating pond 34, so that the amount of water and the quality of water are made uniform.

The adjusting pond 34 is made larger in consideration of a large amount of inflowing sewage, especially during a typhoon season, so that the storage capacity can be adjusted.

Further, in order to keep the sewage rich and prevent sedimentation of suspended matter, aeration and agitation by an aerator (not shown) is performed.

The wastewater collected in the regulating pond 34 is sent to the settling water receiving tank 35, where it is separated into sludge and supernatant wastewater.

In some cases, the treated water after the wastewater from the intermediate treatment facility 36 such as plant wastewater, car wash wastewater, and domestic wastewater has been treated in the combined septic tank 37 of the contact aeration type, etc. flows into the settling water receiving tank 35. To be done.

The sludge settled and separated in the settling water receiving tank 35 is
The water is pumped up by the submersible sludge pump 75, and on the way, the coagulant from the coagulant tank 77 is injected and sent to the sludge storage tank 70.

The sludge from the sludge storage tank 70 is transferred to the dehydrator 71 by the sludge pump 76, dehydrated by the dehydrator 71, stored in the cake hopper 72, and regularly carried out to the outside (landfill). Be disposed of.

The supernatant sewage separated in the settling water receiving tank 35 is sent to the reaction tank 38.

In the reaction tank 38, the pH meter 41 is
PH value 42 of the
3, 44 are generated, and hydrochloric acid in the acid tank 39 or sodium hydroxide in the alkali tank 40 is injected into the reaction tank 38,
The pH value 42 of the sewage is adjusted between 6 and 11.

The reaction tank 38 is not a necessary facility because it does not perform microbial treatment in the subsequent process, but if the acidity or alkalinity of sewage becomes extremely high, the entire facility will be corroded or damaged. It is provided to ensure safety because there is a risk of accidents.

Therefore, normally, injection of acid or alkali hardly occurs.

The wastewater from the reaction tank 38 is used as the diaphragmless electric field tank 4
6 and is subjected to electrodeposition in the diaphragmless electric field tank 46 to coagulate and deposit the ionized products and suspensions dissolved in the wastewater.

That is, a pair of electrodes 4 as shown in FIG.
When a DC voltage of about 1 kV is applied between 7 and 48 using a DC power supply 49, electrolysis occurs in the water in the wastewater,
As water is decomposed into hydrogen and oxygen, electric energy causes a change in the structure of water itself, approaching the structure near the freezing point. That is, the water molecules become finer.

As a result, the solubility of water is lowered, and a suspension or the like dissolved in water is separated from water to be deposited, and the ionized substance in water is also affected by the electric energy.

At this time, the aluminum forming the electrodes 47, 48 is electrolyzed to become ions and dissolve in the wastewater, so that the aggregation of ionized products and suspensions is promoted by the mediation of aluminum ions.

The agglomerated ionized product or suspension is suspended in water by the fine bubbles generated by electrolysis, and moreover, it is uniformly dispersed in water because there is no diaphragm.

The polarities of the electrodes 47 and 48 are periodically exchanged to prevent the electrodes 47 and 48 from being worn out.

In such a diaphragm-free electric field tank 46, a chlorine compound such as trihalomethane, which has been difficult to remove by conventional microbial treatment, can be decomposed and taken out to render it pollution-free.

Further, compared to the conventional microbial treatment, the structure of the tank is simpler, the facility cost can be reduced and the installation area can be halved, and the number of parts is small, so that the labor for maintenance is reduced. be able to.

Furthermore, since the ionized substance and the suspension are coagulated and deposited by electric energy, the amount of chemicals injected can be greatly reduced.

The wastewater in which the ionized substance and the suspension are coagulated and deposited is then sent to the rapid filter 50, and the anthracite (the anthracite-based granular material provided in the rapid filter 50 is provided. Substance) or a filter material such as a ceramic filter or a hollow fiber membrane to obtain a substantially clean treated water from which aggregates are almost completely removed.

The agglomerates filtered and removed by the rapid filter 50 are regularly back-washed with water, air, etc., and the settling water receiving tank 3
Returned to 5.

The treated water that has passed through the rapid filter 50 is then sent to the carbon dioxide gas mixer 51.

Generally, incineration ash from a refuse incineration plant or the like is alkaline, and sewage discharged from the final disposal site 32 such as the waste in which these incineration ash is landfilled is highly likely to be alkaline.

Therefore, in the carbon dioxide mixer 51, the pH
The total 53 detects the pH value 54 of the carbon dioxide mixer 51,
A signal 56 is sent to the carbon dioxide gas controller 55 based on the pH value 54 from the pH meter 53, and the carbon dioxide gas in the carbon dioxide gas cylinder 52 is injected into the carbon dioxide gas mixer 51 to neutralize the treated water.

Here, since the carbonated water has a very weak acidity with a pH value of 5.7, even if carbon dioxide gas is excessively injected into the treated water, the treated water is not acidic drainage (strongly acidic drainage). Instead, it is possible to carry out a neutralizing treatment without pollution.

Moreover, since carbon dioxide is easily dissolved in water,
It is not released from the treated water into the atmosphere and does not affect the global warming phenomenon.

Further, since the carbon dioxide gas controller 55 controls the carbon dioxide gas injection amount, it is possible to prevent the carbon dioxide gas from being excessively injected, and to reduce the running cost.

The treated water discharged from the carbon dioxide gas mixer 51 is guided to an AC voltage type water treatment device 57 as shown in FIG.
The electric energy hinders the growth of scale substances such as calcium ions, magnesium ions and silica dissolved in the treated water.

That is, when the treated water is passed between the electrodes 59 and 60, a low-voltage AC rectangular wave 61 of about 4 W at 100 V is applied from the AC power source 62, whereby crystals of the scale object are needle-like or mica-like. , The area per surface of the crystals becomes smaller, and the cohesive force between the crystals becomes infinitely small, which prevents the single crystals from adhering to each other to grow and block the pipes due to scale adhesion. Also, the difficulty of opening and closing valves is prevented.

As described above, according to the AC voltage type water treatment device 57, since it is not necessary to use chemicals such as scale inhibitors, running cost can be reduced and pollution-free treatment can be performed. .

Further, the installation space is small, and further,
Since there are no moving parts, maintenance can be made almost unnecessary.

The treated water discharged from the AC voltage type water treatment device 57 is
On the way, the flow rate is measured by the flow meter 63, and the disinfectant controller 65 sends a signal 68 to the disinfectant tank 64 in response to the flow rate signal 66 from the flow meter 63. In the flow path 67, a disinfectant such as sodium hypochlorite is injected, and the coliform bacteria count is 3,000 /
Reduced to less than ml.

At this time, since the treated water has its molecular structure temporarily refined and its osmotic force is enhanced by the electric energy applied by the AC voltage type water treatment device 57 in the preceding stage,
Since the disinfectant quickly penetrates into every corner of the treated water, almost no residence time is required.

Therefore, a sufficient disinfecting effect can be obtained by injecting the disinfectant in the middle of the flow path 67 without providing a special disinfecting tank.

The treated water disinfected by the disinfectant is temporarily stored in the treated water storage tank 69 and discharged from the treated water storage tank 69 into a river or the like, or is reused in a plant or the like.

The present invention is not limited to the above-mentioned embodiments, and it goes without saying that various modifications can be made without departing from the gist of the present invention.

[0114]

As described above, according to the sewage treatment method and equipment of the present invention, it is possible to reduce the installation area, minimize the amount of chemicals injected, and reduce equipment cost and running cost. It is possible to obtain an excellent effect that it is possible to reduce the time and maintenance work.

[Brief description of drawings]

FIG. 1 is an overall schematic system diagram of an embodiment of the present invention.

FIG. 2 is a principle view of a diaphragmless electric field tank.

FIG. 3 is a principle diagram of an AC voltage type water treatment device.

FIG. 4 is an overall schematic system diagram of a conventional example.

[Explanation of symbols]

 46 Non-diaphragm electric field tank 50 Rapid filter (filter) 51 Carbon dioxide mixer 57 AC voltage type water treatment device

Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI Technical display location C02F 1/66 510 K 522 B 530 D 540 E

Claims (6)

[Claims] 1. A method for treating sewage, which comprises depositing ionized substances or suspensions dissolved in sewage by coagulation and depositing the sewage to remove the coagulation deposits by filtration. 2. After the wastewater is electrodeposited to coagulate and deposit the ionized products and suspensions dissolved in the wastewater, the coagulated deposits are removed by filtration, and then the filtered treated water is treated with carbon dioxide gas. The sewage treatment method according to claim 1, wherein the sewage treatment method is performed. 3. The sewage is electrodeposited to coagulate and deposit the ionized product or suspension dissolved in the sewage, and the coagulated deposit is removed by filtration, and then the filtered treated water is treated with carbon dioxide gas. The method for treating sewage according to claim 1, further comprising applying electric energy to the treated water to inhibit the growth of scales dissolved in the treated water. 4. A non-diaphragm electric field tank for electrodepositing sewage to coagulate and deposit an ionized product or suspension dissolved in the sewage, and a filter for filtering and removing coagulated deposits by the non-diaphragm electric field tank. Sewage treatment facility characterized by that. 5. A non-diaphragm electric field tank for electrodepositing sewage to coagulate and deposit an ionized product or suspension dissolved in the sewage, and a filter for filtering and removing coagulated deposits by the non-diaphragm electric field tank. A sewage treatment facility according to claim 4, further comprising a carbon dioxide gas mixer for neutralizing the treated water treated with carbon dioxide gas. 6. A non-diaphragm electric field tank for electrodepositing sewage to coagulate and deposit ionized substances and suspensions dissolved in the sewage; a filter for filtering and removing coagulated deposits by the non-diaphragm electric field tank; A carbon dioxide gas mixer for neutralizing the treated water treated with carbon dioxide gas, and an AC voltage type water treatment device for applying an electric energy to the treated water to inhibit the growth of scale matters dissolved in the treated water are characterized. The sewage treatment equipment according to claim 4.