JP2000015266A - Sewage treatment apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sewage treatment apparatus capable of preventing the electrical continuity phenomenon or passivation caused by various sludges accumulated on the bottom of a sewage housing tank to stably and certainly remove phosphoric acid in sewage. SOLUTION: A sewage treatment apparatus D1 is equipped with a sewage housing tank 1, iron electrodes 2, 3, a DC power supply and a water current generating means. Inclined parts 6a, 7a are formed in the opposed side walls 6, 7 of the sewage housing tank 1 and one inclined part 7a guides sludge in sewage so as to allow the sludge to slide down to the vicinity of the central part of a bottom wall 5 to deposit the same while the other inclined part 6a again guides the sludge deposited on the bottom wall 5 upwardly by a circulating water current. An inclined part 5a is also formed in the bottom wall 5 and constituted so as to be downwardly inclined from one inclined part 7a to the other inclined part 6a. The water current generating means is equipped with a blower, an air supply pipe 14 and an air diffusing pipe 15 to generate a circulating water current for circulating sludge in an up and down direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sewage treatment apparatus, and more particularly to a sewage treatment apparatus for removing phosphoric acid contained in sewage such as human wastewater or domestic wastewater by reacting with metal ions eluted by electrolysis. Related to the device.

[0002]

2. Description of the Related Art Conventionally, this type of sewage treatment apparatus has
The following are known.

That is, a sewage storage tank for storing sewage to be treated is provided, and one or more pairs of electrodes made of a water-insoluble phosphate-forming metal are arranged in the tank, and a voltage is applied between these electrodes. This is an apparatus in which phosphoric acid is converted into a water-insoluble phosphate to be precipitated and removed by eluting an electrochemically insoluble phosphate-forming metal ion into wastewater.

[0004]

In such a sewage treatment apparatus, with the progress of sewage treatment, organic sludge or inorganic sludge containing metal oxides, phosphates, and the like is deposited in a sewage storage tank. It accumulates on the bottom. When the deposited sludge comes into contact with the electrode, electrical conduction occurs at the contact point, and there is a possibility that the elution of desired metal ions is partially prevented.

When such an electrical conduction phenomenon occurs, a corrosion-resistant oxide film called a passive film is formed on the surface of the electrode, so that the elution of water-insoluble phosphate-forming metal ions is reduced. Or stop (passivation). When such passivation occurs, it becomes difficult or impossible to remove the phosphoric acid in the wastewater into a water-insoluble phosphate.

[0006] The present invention has been made in view of such circumstances, and an object thereof is to prevent an electrical conduction phenomenon and passivation caused by various kinds of sludge deposited on the bottom of a sewage storage tank. An object of the present invention is to provide a sewage treatment apparatus capable of stably and reliably removing phosphoric acid in sewage.

[0007]

According to the present invention, a sewage storage tank having one bottom wall and two sets of opposed side walls, and phosphoric acid in the sewage disposed in the sewage storage tank for removing phosphoric acid in the sewage is removed. At least one set of electrodes for eluting iron or aluminum ions by electrolysis, a power supply for supplying an electrolytic current to the electrodes, and a circulation for circulating sludge deposited in a sewage storage tank in the tank. A water flow generating means for generating a water flow, and a pair of opposed side walls in the sewage storage tank are provided with an inclined portion at each lower portion for accumulating sludge near the center of the bottom wall or guiding the sludge upward by a circulating water flow. A water flow generating means is provided, and a blower for compressed air supply arranged outside the tank, an air supply pipe connected to the blower for supplying compressed air, and a bottom part in the tank connected to the air supply pipe. Dealt and supplied Sewage treatment device including a compressed air from a plurality of outlet holes and the aeration tube for blowing diagonally downward and is provided.

The sewage storage tank stores sewage to be subjected to electrolysis. The electrodes are, for example, rectangular plate-shaped ones in a predetermined set of two, and elute iron or aluminum ions into the sewage storage tank by electrolysis. A power supply supplies a current for electrolysis to each set of electrodes.

The set of electrodes is, for example, both iron (or aluminum) electrodes, or one is an iron (or aluminum) electrode and the other is an insoluble metal electrode. In the former case, the passivation of the electrode can be prevented by inverting the polarity of the electrode as desired. In the latter case, an iron (or aluminum) electrode is used as an anode, and an insoluble metal electrode is used as a cathode. Here, examples of the insoluble metal electrode include a silver electrode and a platinum electrode. Further, it is preferable that the pair of electrodes is fixed to, for example, an electrically insulating spacer having a handle, and the interval between the electrodes is kept constant.

The iron ions or aluminum ions eluted into the sewage storage tank by electrolysis react with phosphoric acid (orthophosphoric acid) in the sewage to form a water-insoluble phosphorus compound (Fe).
(OH) _x (PO ₄ ) _y or Al (OH) _x (P
O ₄ ) _y ) and coagulate, settle and deposit in the sewage storage tank.

[0011] The water flow generating means generates a circulating water flow for vertically circulating the sludge deposited in the sewage storage tank in the tank. That is, the water flow generating means includes a blower for supplying compressed air provided outside the tank, an air supply pipe connected to the blower for supplying compressed air, and a blower connected to the air supply pipe and provided at a bottom in the tank. And a diffuser for blowing the supplied compressed air obliquely downward from the plurality of outlets.

Due to the circulating water flow generated by the water flow generating means, a part of the sludge is suspended in the sewage without being accumulated, and the sewage discharge pipe provided on the side wall of the sewage storage tank is formed. It easily flows out of the tank.

Therefore, it is possible to prevent the electrical conduction phenomenon and the passivation caused by various kinds of sludge deposited on the bottom of the sewage storage tank, and to stably and surely remove the phosphoric acid in the sewage. .

[0014] On a pair of opposed side walls in the sewage storage tank,
An inclined portion is provided at each lower portion. These inclined portions are for accumulating sludge near the center of the bottom wall or guiding the sludge upward by circulating water flow. That is, one of the inclined portions has a function of guiding the sludge in the sewage to slide down to the vicinity of the center of the bottom wall and depositing the sludge, and the other inclined portion has a function of circulating the sludge deposited near the center of the bottom wall. Has the function of guiding upward again.

The inclination angle of each inclined portion-the angle formed by the inclined portion and the horizontal plane-is determined by the size of the sewage storage tank, the number and arrangement of the electrodes, the number of the supply pipes and the diffuser pipes. And the arrangement state, the strength and direction of the circulating water flow, and the like. One example is about 40 to 60 degrees.

In the sewage treatment apparatus according to the present invention, more preferably, the slant for guiding sludge deposited in the sewage storage tank from one inclined portion of the set of opposed side walls to the other inclined portion is provided on the bottom wall. A part is provided.

[0017] The inclined portion extends from a position near the bottom wall (a position where the sludge is guided to slide down the inclined portion of the side wall) on one inclined portion of the pair of opposed side walls to the other inclined portion. It is configured so as to be inclined downward toward a location near the bottom wall (a location where the sludge is guided upward again by the circulating water flow) in the portion.

With such a configuration, the sludge guided to slide down one inclined portion of the side wall is:
In addition, it is guided to slide down the slope of the bottom wall,
It accumulates at a position near the bottom wall of the other inclined portion of the side wall. Therefore, it is easier to guide the sludge upward by the circulating water flow thereafter.

In the sewage treatment apparatus according to the present invention, more preferably, the electrode is disposed substantially parallel to a line connecting the sewage inflow portion and the sewage outflow portion in the sewage storage tank, and the diffuser pipe is connected to the sewage inflow portion. The circulating water flow is arranged to be generated in a direction substantially parallel to a line connecting the sewage discharge section. The sewage inflow section
For example, a portion where sewage flows into a sewage storage tank from a sewage inflow pipe disposed above or above one side wall. The sewage outflow portion is, for example, a portion where sewage from the sewage storage tank flows out to a sewage outflow pipe provided at an upper portion of another one side wall.

When the electrode and the air diffuser are configured as described above, the sewage flowing into the sewage storage tank rides on the circulating water flow that flows smoothly in a direction substantially parallel to the electrode, and the sewage inflow portion and the sewage outflow portion Since the air circulates substantially parallel to the line connecting the air and the air, the air blown out from the air diffuser rides on the circulating water flow to efficiently clean the electrode surface. Further, when the sludge in the suspended state comes near the sewage outflow portion, the sludge easily flows out of the tank through the sewage outflow portion.

Here, more preferably, the air outlets of the air diffuser are provided in a pair immediately below the electrodes and in pairs for each electrode. It is open toward. The opening positions of these blow holes are provided, for example, shifted inward by an angle of several degrees with respect to the vertical line.

Since the air holes of the air diffuser are provided immediately below the electrodes and in pairs for each electrode, the air blown out from the air holes requires the surface of the electrodes in the sewage to be used. The part can be efficiently cleaned.

[0023] In addition, since the pair of outlets is opened obliquely downward and inward, it is possible to prevent the settling sludge from blocking the outlets, and to blow out the two outlets downward. The air first rises in the sewage to approach each other. For this reason, the water flow generated by the blowing of air rises first to approach each other, and then moves toward the pair of opposed side walls so as to separate from each other,
Thereafter, it circulates down along each side wall and approaches each other again. At this time, as described above, since the electrodes are arranged substantially parallel to the line connecting the sewage inflow portion and the sewage outflow portion, the circulating water flow is formed below the electrode in the sewage →
It follows the path from the inner middle part → the inner upper part → the inner middle part → the lower part, and almost equally hits most of the electrode surface.
Therefore, it is possible to clean a required portion of the electrode surface almost evenly by the circulating water flow.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. Note that the present invention is not limited by this.

As shown in FIGS. 1 to 3, a sewage treatment apparatus D _{1 according} to one embodiment of the present invention includes one sewage storage tank 1, two sets of electrodes 2 and 3, A DC power supply (not shown) for supplying a current to the electrodes 2 and 3 and one electrode holder 4 are provided.

The sewage storage tank 1 has one bottom wall 5 and two sets of opposing side walls 6, 7, 8, and 9, and is formed of a box having a substantially rectangular planar shape, and is used for storing waste water and domestic waste water. Wastewater to be treated is stored. Above one side wall 8 of the sewage storage tank 1, a sewage inflow pipe 10 for flowing sewage to be subjected to electrolytic treatment into the sewage inflow section of the sewage storage tank 1 is arranged, and above the other one side wall 6. Is provided with a sewage outflow pipe 11 for allowing sewage after electrolytic treatment to flow out from a sewage outflow portion in the sewage storage tank 1.

Each of the electrodes 2 and 3 of each set is a rectangular plate-shaped iron plate, and elutes iron ions for removing phosphoric acid in wastewater by electrolysis. The distance between the pair of electrodes 2 and 3 is kept constant by an electrically insulating spacer 12 made of vinyl chloride resin attached to the upper end thereof.

This sewage treatment apparatus D ₁ has a water flow generating means. The water flow generating means is provided with a circulating water flow (FIG. 1) for vertically circulating the sludge deposited in the sewage storage tank 1 in the tank.
(Indicated by a black arrow).

That is, as shown in FIGS. 1 to 5, the water flow generating means is a blower 13 for supplying compressed air provided outside the tank.
(Shown in FIG. 7), an air supply pipe 14 connected to the blower 13 for supplying compressed air, and a compressed air supplied to the air supply pipe 14 and arranged at the bottom of the tank in a square frame shape. And a diffuser 15 for blowing diagonally downward from a plurality of outlets 15a.

As shown in FIG. 1, a pair of opposed side walls 6 and 7 in the sewage storage tank 1 have inclined portions 6 at their lower portions.
a.7a is provided. The one inclined portion 7 a has a function of guiding and depositing the sludge in the sewage so as to slide down near the center of the bottom wall 5. The other inclined portion 6a
Has a function of guiding the sludge accumulated near the center of the bottom wall 5 upward again by the circulating water flow. The inclination angles α and β of the inclined portions 6a and 7a and the angle formed by the inclined portions 6a and 7a and the horizontal plane are all 45 degrees.

The bottom wall 5 is also provided with an inclined portion 5a.
That is, the inclined portion 5a extends over the entire bottom wall 5, and a portion of the one side wall 7 near the bottom wall 5 in the inclined portion 7a (so that the sludge is guided and deposited so as to slide down the inclined portion 7a of the side wall 7). ) From the bottom wall 5 of the inclined portion 6a of the other side wall 6 (a place where the sludge is guided upward again by the circulating water flow). The inclination angle γ of the inclined portion 5a-the angle formed between the inclined portion 5a and the horizontal plane-is set to about 5 degrees.

As shown in FIG. 2, two sets of electrodes 2.3 are
The sewage storage tank is arranged substantially parallel to a line connecting the sewage inflow portion and the sewage outflow portion.

The air diffuser 15 is arranged to generate a circulating water flow in a direction substantially parallel to a line connecting the sewage inflow portion and the sewage outflow portion. That is, the blowout holes 15a of the air diffuser 15 are provided immediately below the electrodes 2 and 3 in pairs for each set of the electrodes 2.3.
Each set of outlets 15a is open obliquely downward and inward. The opening positions of these blow holes 15a are, for example,
It is provided shifted inward by an angle δ (about 5 degrees) with respect to the vertical line.

As shown in FIGS. 6 and 7, the sewage treatment apparatuses D ₁ is incorporated in a small combined treatment septic tank 101.

The inside of the septic tank 101 is located at a side of an inflow pipe 102 into which sewage mixed with human wastewater and domestic wastewater flows.
A tank structure is formed in which a plurality of tanks are defined and formed in accordance with the order of the sewage purification process on the side of the discharge pipe 103 for discharging sewage treated water to the outside. 104 is an inflow pipe 102
It is the 1st anaerobic filter bed tank formed in the forefront part of the side. In the first anaerobic filter bed tank 104, impurities that are mixed in human wastewater or domestic wastewater and cannot be purified are removed by sedimentation.

The first anaerobic filter bed tank 104 is provided with a first anaerobic filter bed 105 which is a filter bed for anaerobic microorganisms.
Anaerobic treatment is performed by inhabiting microorganisms in the anaerobic filter bed 105. The first anaerobic filter bed 105 prevents the sediment from being lifted up by the water flow when the inflow water or backwash wastewater temporarily flows in and becomes a suspended substance and flows out to the next tank. The load can be reduced.

Reference numeral 106 denotes a next second anaerobic filter bed tank formed adjacent to the first anaerobic filter bed tank 104. In the second anaerobic filter bed tank 106, anaerobic treatment is performed by inhabiting the anaerobic microorganisms in the second anaerobic filter bed 107.

Reference numeral 108 denotes a next aerobic filter tank formed adjacent to the second anaerobic filter tank 106. The first anaerobic filter tank 104 and the second anaerobic filter tank 106 are separated by a vertical partition wall 109. At the upper part of the partition wall 109, an advection port 110 penetrating the partition wall 109 is formed. And
An advection tube 111 is fitted in the advection port 110. The second anaerobic filter tank 106 and the next aerobic filter tank 108 are separated by a vertical partition 112. In the upper part of the partition 112, an advection port 113 penetrating the partition 112 is formed.
An advection tube 114 is fitted in the advection port 113.

The sewage that has flowed from the first anaerobic filter bed tank 104 to the second anaerobic filter bed tank 106 through the advection tube 111 passes through the second anaerobic filter bed 107 in a downward flow, and then flows through the advection tube 114.
To the next aerobic filter bed tank 108.

A certain amount of SS is captured by the second anaerobic filter bed 107 provided in the second anaerobic filter bed tank 106. The trapped SS is gradually anaerobically decomposed and becomes soluble, or is stored as sludge at the bottom of the second anaerobic filter tank 106. In the second anaerobic filter bed 107, organic nitrogen is anaerobically decomposed into ammonia nitrogen.

The aerobic filter bed tank 108 is provided with an aerobic filter bed 115 which is a filter bed for aerobic microorganisms.
The aerobic treatment is carried out by inhabiting aerobic microorganisms in No. 15. Near the bottom of the aerobic filter bed tank 108,
The aeration tube 116 of the aeration device is disposed horizontally. The aeration apparatus supplies oxygen to the aerobic microorganisms living in the aerobic filter bed 115 of the aerobic filter bed tank 108 by blowing out air from the aeration pipe 116.

Reference numeral 125 denotes a backwash pipe which is switchably connected to the aeration apparatus and is provided below the aerobic filter bed 115. By blowing air from the backwash pipe 125, the aerobic filter 1 is discharged.
The biofilm attached to 15 is peeled off. Reference numeral 117 denotes the next settling tank formed adjacent to the aerobic filter bed tank 108.
In the sedimentation tank 117, aerobic treatment is performed in the aerobic filter bed tank 108,
The treated water that has been filtered and advected is stored still.

Reference numeral 118 denotes a disinfecting tank formed above the sedimentation tank 117. The disinfecting tank 118 is configured to disinfect the supernatant water that has been treated in the sedimentation tank 117 and discharge the same from the discharge pipe 103 to the outside.

The aerobic filter bed tank 108 and the next sedimentation tank 117 are separated by a vertical partition wall 119 except for the lower part. The sewage which has flowed from the second anaerobic filter tank 106 to the aerobic filter tank 108 through the convection pipe 114 is subjected to the aerobic filter bed 115.
, And then sent to the next settling tank 117.

A return pipe 122 for returning the supernatant water of the treated water is provided from the upper portion of the aerobic filter tank 108 to the upper portion of the first anaerobic filter tank 104. Then, the supernatant water pumped up by the lift tube 123 from the aerobic filter bed tank 108, after being subjected diversion metering device 124, is sent to the sewage treatment apparatuses D ₁ through the return pipe 122 to the phosphorus removal process, the 1 Returned to the anaerobic filter bed tank 104.

[0046]

According to the first aspect of the present invention, a sewage storage tank having one bottom wall and two sets of opposing side walls, and phosphoric acid in the sewage disposed in the sewage storage tank is provided. At least one set of electrodes for eluting iron or aluminum ions by electrolysis for removal, a power supply for supplying electrolysis current to the electrodes, and a system for circulating sludge deposited in a sewage storage tank in the tank. A water flow generating means for generating a circulating water flow, and a pair of opposed side walls in the sewage storage tank, at each lower part, an inclined portion for accumulating sludge near the center of the bottom wall or guiding the sludge upward by the circulating water flow. A water flow generating means, a blower for compressed air supply arranged outside the tank, an air supply pipe connected to the blower for supplying compressed air, and a bottom part in the tank connected to the air supply pipe. Distributed and supplied Compressed air from a plurality of outlet holes formed by a diffusing pipe for blowing obliquely downward with. According to such a configuration, a part of the sludge in the sewage is suspended in the sewage without being accumulated due to the circulating water flow generated by the water flow generation means, and the inclined portion on one side wall has the sludge. Has a function of guiding the sludge to slide down to the vicinity of the center of the bottom wall, and has a function of guiding the sludge deposited near the center of the bottom wall upward again by the circulating water flow. Therefore, the sludge in the sewage easily flows out of the sewage tank through a sewage outflow pipe provided on the side wall of the sewage storage tank, and prevents electrical conduction phenomena and passivation caused by the accumulated sludge. It becomes possible to remove the phosphoric acid therein stably and reliably.

According to the second aspect of the present invention, the bottom wall is provided with an inclined portion for guiding the sludge accumulated in the sewage storage tank from one inclined portion of the pair of opposed side walls to the other inclined portion. Have been. Therefore, the sludge guided to slide down one slope of the side wall is further guided to slide down the slope of the bottom wall, and accumulates at a position near the bottom wall of the other slope of the side wall. Therefore, it is easier to guide the sludge upward by the circulating water flow thereafter, and the effect according to the first aspect of the invention can be more reliably achieved.

According to the third aspect of the present invention, the electrode is disposed substantially parallel to a line connecting the sewage inflow portion and the sewage outflow portion in the sewage storage tank, and the diffuser pipe is provided in the sewage inflow portion and the sewage outflow portion. And a circulating water flow is generated in a direction substantially parallel to the line connecting. Therefore, the sewage flowing into the sewage storage tank rides on the circulating water flow that flows smoothly in a direction substantially parallel to the electrode, and circulates substantially parallel to the line connecting the sewage inflow portion and the sewage outflow portion. The air blown out of the electrode rides on the circulating water flow to efficiently clean the electrode surface. Further, when the sludge in the suspended state comes near the sewage outflow portion, the sludge easily flows out of the tank through the sewage outflow portion.

According to the fourth aspect of the present invention, the blow holes of the air diffuser are provided in a pair immediately below the electrodes and in pairs for each set of the electrodes. It opens diagonally downward and inward. Therefore, it is possible to prevent the possibility that the blow-off hole is blocked by the settling sludge, and, by the air blown out from the blow-out hole provided immediately below the electrode and in a pair of two per electrode set, It is possible to efficiently clean the required part of the electrode surface in the sewage, and it is possible to wash the required part of the electrode surface almost evenly by the circulating water flow that hits most of the electrode surface almost evenly. .

[Brief description of the drawings]

FIG. 1 is a front sectional view of a sewage treatment apparatus according to one embodiment of the present invention.

FIG. 2 is a configuration explanatory view of the sewage treatment apparatus of FIG. 1 as viewed from above.

FIG. 3 is a side sectional view of the sewage treatment apparatus of FIG. 1;

FIG. 4 is an enlarged plan view showing a part of an air diffuser constituting the sewage treatment apparatus of FIG. 1;

FIG. 5 is a front sectional view of the air diffusion tube of FIG. 4;

FIG. 6 is an explanatory view of the configuration of the inside of a combined treatment septic tank incorporating the sewage treatment apparatus of FIG. 1 as viewed from the front.

FIG. 7 is an explanatory view of the configuration of the inside of the combined treatment septic tank of FIG. 6 as viewed from above.

[Explanation of symbols]

D ₁ Sewage treatment apparatus 1 Sewage storage tank 2 Electrode 3 Electrode 5 Bottom wall 5a Inclined section 6 Side wall 6a Inclined section 7 Side wall 7a Inclined section 8 Side wall 9 Side wall 10 Sewage inflow pipe 11 Sewage outflow pipe 13 Blower (water flow generating means) 14 Supply Trachea (water flow generating means) 15 Air diffuser (water flow generating means) 15a Blow-out hole (water flow generating means) 101 Small-sized combined treatment septic tank

Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat II (reference) C02F 3/00 F term (reference) 4D027 AA01 AA11 AA16 AB01 AB11 AB16 BA04 BA05 4D038 AA08 AB46 AB47 BA02 BB10 BB19 4D061 AA08 AB09 AC13 BA02 BA03 BB01 BB04 BB27 BB28 BB30 BB31 BD06 CA15 4D062 BA19 BB01 CA01 CA03 FA12 FA25 FA26

Claims (4)

[Claims] 1. A wastewater storage tank having one bottom wall and two sets of opposed side walls, and an iron ion or an aluminum ion disposed in the wastewater storage tank for precipitating and removing phosphoric acid in the wastewater. At least one set of electrodes eluted by decomposition, a power supply for supplying an electrolytic current to the electrodes, and a water flow generating means for generating a circulating water flow for circulating sludge deposited in the sewage storage tank in the tank are provided. A pair of opposed side walls in the sewage storage tank are provided with a sloped portion at each lower portion for accumulating sludge near the center of the bottom wall or guiding the sludge upward by a circulating water flow. A blower for supplying compressed air connected to the blower, and a supply pipe connected to the blower for supplying compressed air, and a plurality of compressed air supplied to the bottom of the tank connected to the supply pipe and provided. From the outlet Sewage treatment apparatus comprising a diffusing pipe for blowing to fit downwardly. 2. The bottom wall is provided with an inclined portion for guiding sludge accumulated in the sewage storage tank from one inclined portion of the pair of opposed side walls to the other inclined portion. Sewage treatment equipment. 3. An electrode is disposed substantially parallel to a line connecting a sewage inflow portion and a sewage outflow portion in the sewage storage tank, and a diffuser pipe is substantially parallel to a line connecting the sewage inflow portion and the sewage outflow portion. The sewage treatment apparatus according to claim 1, wherein the sewage treatment apparatus is arranged to generate a circulating water flow in any direction. 4. A blow-off hole of an air diffuser tube is provided immediately below the electrode and in a pair of two for each set of electrodes, and the pair of blow-off holes opens diagonally downward and inward. The sewage treatment apparatus according to claim 3, wherein