JP3948832B2 - Sewage treatment equipment - Google Patents

Description

[0001]
BACKGROUND 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 manure wastewater and domestic wastewater by reacting with metal ions eluted by electrolysis.
[0002]
[Prior art]
As this kind of sewage treatment apparatus, conventionally, the following is known.
[0003]
That is, a sewage storage tank for storing sewage to be treated is provided, and one or more sets of electrodes made of a water-insoluble phosphate forming metal are arranged in the tank, and a voltage is applied between these electrodes to In this apparatus, phosphoric acid is converted into a water-insoluble phosphate by eluting chemically insoluble phosphate-forming metal ions into the sewage, thereby removing the precipitate.
[0004]
[Problems to be solved by the invention]
In such a sewage treatment apparatus, as the sewage treatment progresses, organic sludge or inorganic sludge containing metal oxides, phosphates, and the like accumulates on the bottom of the sewage storage tank. When the accumulated sludge comes into contact with the electrode, electrical conduction occurs at the contact location, which may partially prevent elution of desired metal ions.
[0005]
When such an electrical continuity phenomenon occurs, a corrosion-resistant oxide film called a passive film is formed on the surface of the electrode. As a result, elution of water-insoluble phosphate-forming metal ions is reduced or stopped. (Passivation). When such passivation occurs, it becomes difficult or impossible to remove phosphoric acid in wastewater as a water-insoluble phosphate.
[0006]
The present invention has been made in view of such circumstances, and its problem is to prevent electrical continuity and passivation caused by various sludge accumulated on the bottom of the sewage storage tank, An object of the present invention is to provide a sewage treatment apparatus capable of stably and reliably removing phosphoric acid.
[0007]
[Means for Solving the Problems]
According to the present invention, a sewage storage tank having one bottom wall and two sets of opposing side walls, and iron ions or aluminum ions disposed in the sewage storage tank and used to precipitate and remove phosphoric acid in the sewage At least a pair of electrodes eluted by electrolysis, a power source for supplying electrolysis current to the electrodes, and a water flow generating means for generating a circulating water flow for circulating sludge accumulated in the sewage storage tank in the tank And a pair of opposing side walls in the sewage storage tank are provided with inclined portions for depositing sludge near the center of the bottom wall or guiding it upward by a circulating water flow at each lower part. A blower for supplying compressed air arranged outside, an air supply pipe for supplying compressed air connected to the blower, and a compressed air supplied to the bottom of the tank connected to the air supply pipe. Multiple vents Sewage treatment apparatus is provided comprising a diffusing pipe for blowing diagonally downward.
[0008]
The sewage storage tank stores sewage used for electrolysis. The electrodes are, for example, a set of two rectangular plates that are arranged in a set, and elute iron ions or aluminum ions into the sewage storage tank by electrolysis. The power supply supplies current for electrolysis to each set of electrodes.
[0009]
One 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, it is possible to prevent electrode passivation by reversing 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 portion, and the distance between them is kept constant.
[0010]
Iron ions or aluminum ions eluted in the sewage storage tank by electrolysis react with phosphoric acid (orthophosphoric acid) in the sewage water to form water-insoluble phosphorus compounds (Fe (OH) _x (PO ₄ ) _y or Al (OH) _x (PO ₄ ) _y ) and agglomerates, and precipitates and accumulates in the sewage storage tank.
[0011]
The water flow generating means generates a circulating water flow for circulating the sludge accumulated in the sewage storage tank vertically in the tank. That is, the water flow generating means includes a compressed air supply blower arranged outside the tank, an air supply pipe connected to the blower for supplying compressed air, and connected to the air supply pipe at the bottom of the tank. And a diffuser pipe for blowing the supplied compressed air obliquely downward from the plurality of blowing holes.
[0012]
Due to the circulating water flow generated by such water flow generating means, part of the sludge is suspended in the sewage without accumulating, and the tank passes through the sewage outflow pipe provided on the side wall of the sewage storage tank. It becomes easy to flow out.
[0013]
Therefore, it is possible to stably and reliably remove phosphoric acid in the sewage by preventing electrical continuity and passivation caused by various sludge accumulated on the bottom of the sewage storage tank.
[0014]
The pair of opposed side walls in the sewage storage tank are provided with inclined portions at the lower portions thereof. These inclined portions are for depositing sludge near the center of the bottom wall or for guiding it upward by a circulating water flow. That is, one inclined portion has a function of guiding and depositing sludge in the sewage so as to slide down near the center of the bottom wall, and the other inclined portion allows the sludge accumulated near the center of the bottom wall to flow through the circulating water flow. The function of guiding upward again is provided.
[0015]
The inclination angle of each inclined part-the angle formed by the inclined part and the horizontal plane-is the size of the sewage storage tank, the number and arrangement of the electrodes, the number and arrangement of the supply pipes and diffuser pipes It is determined appropriately depending on the state, the strength and direction of the circulating water flow, and the like. As an example, it is about 40 to 60 degrees.
[0016]
More preferably, the sewage treatment apparatus according to the present invention is provided with an inclined portion for guiding the sludge accumulated in the sewage storage tank from one inclined portion to the other inclined portion of the pair of opposing side walls on the bottom wall. It is done.
[0017]
This inclined portion is located at the bottom wall in the other inclined portion from the portion near the bottom wall in one inclined portion of the pair of opposing sidewalls (the portion where the sludge is guided and accumulated so as to slide down the inclined portion of the sidewall). It is comprised so that it may become a downward slope toward the wall side location (location where sludge is again guided upward by the circulating water flow).
[0018]
By being configured in this manner, the sludge guided so as to slide down one inclined portion of the side wall is further guided so as to slide down the inclined portion of the bottom wall, and is located near the bottom wall of the other inclined portion of the side wall. Will begin to accumulate. Therefore, the upward sludge guide by the circulating water flow thereafter becomes even easier.
[0019]
More preferably, in the sewage treatment apparatus according to 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 air diffuser includes the sewage inflow portion and the sewage outflow portion. Circulating water flow is arranged in a direction almost parallel to the line connecting the two. A sewage inflow part is a part into which sewage flows into a sewage storage tank, for example from the sewage inflow pipe distribute | arranged above or the upper part of one side wall. A sewage outflow part is a part from which the sewage from a sewage storage tank flows out into the sewage outflow pipe provided in the upper part of another one side wall, for example.
[0020]
When the electrode and the air diffuser are configured in this way, the sewage that has flowed into the sewage storage tank rides on a circulating water flow that smoothly flows in a direction substantially parallel to the electrode, and connects the sewage inflow part and the sewage outflow part. Since the air circulates substantially parallel to the line, the air blown from the air diffuser rides on the circulating water stream and efficiently cleans the electrode surface. Further, when the sludge in a suspended state comes close to the sewage outflow part, it easily flows out of the tank through the sewage outflow part.
[0021]
Here, more preferably, the blowout holes of the air diffuser are provided immediately below the electrodes and in pairs, and the two pairs of blowout holes are inclined inward and downward. It is open. The opening positions of these blowout holes are, for example, shifted inward by an angle of several degrees with respect to the vertical line.
[0022]
The air blowout holes of the diffuser tube are provided directly below the electrodes and in pairs, so that the necessary part of the surface of the electrode in the sewage is efficiently used by the air blown out from the blowout holes. It becomes possible to wash well.
[0023]
In addition, since the two pairs of blowing holes are opened obliquely downward and inward, the air blown downward from the two blowing holes is prevented while preventing the blowing holes from being blocked by the settling sludge. First, the sewage rises to approach each other. For this reason, the water flow generated by the air blowing first rises so as to approach each other, then moves toward a pair of opposing side walls so as to leave each other, and then descends along each side wall to approach each other again. It circulates to. At this time, as described above, since the electrode is arranged substantially parallel to the line connecting the sewage inflow part and the sewage outflow part, the circulating water flow is lower part of the electrode in the sewage → inner middle part → inner upper part. → The inner middle part → the lower part of the path is followed, and it hits most of the electrode surface almost evenly. Therefore, it becomes possible to wash the necessary part of the electrode surface almost uniformly by the circulating water flow.
[0024]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, one embodiment of the present invention will be described with reference to the drawings. Note that the present invention is not limited thereby.
[0025]
As shown in FIGS. 1 to 3, a sewage treatment apparatus D _{1 according} to an embodiment of the present invention includes one sewage storage tank 1, two sets of electrodes 2 and 3, and each set of electrodes 2 and 3. 3 is provided with a direct current power source (not shown) for supplying current to 3 and one electrode holder 4.
[0026]
The sewage storage tank 1 has a bottom wall 5 and two sets of opposing side walls 6, 7, 8, 9 and is a box having a substantially square shape, and should be treated for wastewater from urine and domestic wastewater. Sewage is stored. Above one side wall 8 of the sewage storage tank 1, a sewage inflow pipe 10 for allowing the sewage to be electrolyzed to flow into the sewage inflow part of the sewage storage tank 1 is disposed, and above the other one side wall 6. Is provided with a sewage outflow pipe 11 for allowing the sewage after the electrolytic treatment to flow out from the sewage outflow portion in the sewage storage tank 1.
[0027]
Each pair of electrodes 2 and 3 is a rectangular iron plate, and elutes iron ions for removing phosphoric acid in the sewage by electrolysis. The distance between the pair of electrodes 2 and 3 is kept constant by the electrically insulating spacer 12 made of vinyl chloride resin attached to the upper ends thereof.
[0028]
The sewage treatment apparatuses D ₁ is provided with a water flow generating means. The water flow generating means generates a circulating water flow (indicated by black arrows in FIG. 1) for circulating the sludge accumulated in the sewage storage tank 1 in the vertical direction.
[0029]
That is, as shown in FIGS. 1 to 5, the water flow generating means is connected to the compressed air supply blower 13 (shown in FIG. 7) disposed outside the tank and connected to the blower 13 to supply the compressed air. The air supply pipe 14 and the air supply pipe 14 connected to the air supply pipe 14 and arranged in a rectangular frame shape at the bottom of the tank, are provided with a diffuser pipe 15 for blowing the supplied compressed air obliquely downward from the plurality of blow holes 15a. .
[0030]
As shown in FIG. 1, the pair of opposed side walls 6, 7 in the sewage storage tank 1 are provided with inclined portions 6 a, 7 a at their lower portions. The one inclined portion 7 a has a function of guiding and depositing sludge in the sewage so as to slide down to the vicinity of 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 these inclined portions 6a and 7a—the angles formed by the inclined portions 6a and 7a and the horizontal plane—are all set to 45 degrees.
[0031]
The bottom wall 5 is also provided with an inclined portion 5a. That is, the inclined portion 5 a extends over the entire bottom wall 5, and is located near the bottom wall 5 in the inclined portion 7 a of one side wall 7 (sludge is guided and accumulated so as to slide down the inclined portion 7 a of the side wall 7. The portion of the inclined portion 6a of the other side wall 6 is inclined downward from the portion of the inclined portion 6a of the other side wall 6 (the portion where the sludge is again guided upward by the circulating water flow). The inclination angle γ of the inclined part 5a—the angle formed by the inclined part 5a and the horizontal plane—is about 5 degrees.
[0032]
As shown in FIG. 2, the two sets of electrodes 2 and 3 are arranged substantially parallel to a line connecting the sewage inflow portion and the sewage outflow portion in the sewage storage tank.
[0033]
The air diffuser 15 is arranged so as 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 and in pairs of the electrodes 2 and 3, and these two pairs of blowout holes 15a It is opened diagonally downward and inward. The opening positions of these blowout holes 15a are provided so as to be shifted inward by an angle δ (about 5 degrees) with respect to the vertical line, for example.
[0034]
As shown in FIGS. 6 and 7, the sewage treatment apparatuses D ₁ is incorporated in a small combined treatment septic tank 101.
[0035]
The inside of the septic tank 101 is in accordance with the order of the sewage purification process from the side of the inflow pipe 102 into which sewage mixed with urine wastewater and domestic wastewater flows to the side of the discharge pipe 103 that discharges sewage-treated water to the outside. The tank structure is formed by partitioning a plurality of tanks. Reference numeral 104 denotes a first anaerobic filter bed tank formed in the foremost part on the inflow pipe 102 side. In the first anaerobic filter bed tank 104, impurities that cannot be purified by being mixed in manure wastewater or domestic wastewater are separated by precipitation and removed.
[0036]
The first anaerobic filter bed tank 104 is provided with a first anaerobic filter bed 105 which is a filter bed for anaerobic microorganisms, and anaerobic treatment is performed by causing the first anaerobic filter bed 105 to inhabit the microorganisms. Yes. The first anaerobic filter bed 105 suppresses the sediment from being rolled up by the water flow when the inflow water or backwash wastewater temporarily flows into the suspended tank and flowing out to the next tank. The load can be reduced.
[0037]
Reference numeral 106 denotes a second 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 causing the second anaerobic filter bed 107 to inhabit anaerobic microorganisms.
[0038]
Reference numeral 108 denotes a next aerobic filter bed tank formed adjacent to the second anaerobic filter bed tank 106. The first anaerobic filter bed tank 104 and the second anaerobic filter bed tank 106 are partitioned by a vertical partition wall 109. An advection port 110 penetrating the partition wall 109 is formed in an upper part of the partition wall 109. A convection tube 111 is fitted in the convection port 110. The second anaerobic filter bed tank 106 and the next aerobic filter bed tank 108 are partitioned by a vertical partition 112. An advection port 113 penetrating the partition 112 is formed in an upper part of the partition 112. A convection tube 114 is fitted into the convection port 113.
[0039]
The sewage that has been transferred from the first anaerobic filter bed tank 104 to the second anaerobic filter bed tank 106 through the transfer pipe 111 passes through the second anaerobic filter bed 107 in a downward flow, and then passes through the transfer pipe 114 to the next. It is sent to the aerobic filter bed tank 108.
[0040]
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 to become soluble, or stored as sludge at the bottom of the second anaerobic filter bed tank 106. In the second anaerobic filter bed 107, organic nitrogen is anaerobically decomposed into ammonia nitrogen.
[0041]
The aerobic filter bed 108 is provided with an aerobic filter bed 115 which is a filter bed of aerobic microorganisms, and aerobic treatment is performed by causing the aerobic microorganisms to inhabit the aerobic filter bed 115. ing. In the vicinity of the bottom of the aerobic filter bed 108, an aeration pipe 116 of the aeration apparatus is arranged in a horizontal state. The aeration apparatus supplies oxygen to aerobic microorganisms that inhabit the aerobic filter bed 115 of the aerobic filter bed tank 108 by blowing out air from the aeration pipe 116.
[0042]
Reference numeral 125 denotes a backwash pipe connected to the aeration apparatus in a switchable manner and provided below the aerobic filter bed 115, and the biofilm attached to the aerobic filter bed 115 by blowing air from the backwash pipe 125. To peel off. Reference numeral 117 denotes a next sedimentation tank formed adjacent to the aerobic filter bed tank 108. In the settling tank 117, the treated water which has been aerobically treated in the aerobic filter bed tank 108, filtered and transferred is stored stationary.
[0043]
Reference numeral 118 denotes a disinfection tank that is partitioned on the upper part of the settling tank 117. The disinfecting tank 118 disinfects the supernatant water that has been processed in the settling tank 117 and discharges it from the discharge pipe 103 to the outside.
[0044]
The aerobic filter bed tank 108 and the next settling tank 117 are partitioned by a vertical partition wall 119 leaving a lower part. The sewage that has been transferred from the second anaerobic filter bed tank 106 to the aerobic filter bed tank 108 through the advection pipe 114 passes through the aerobic filter bed 115 in a downward flow, and then is sent to the next settling tank 117.
[0045]
From the upper part of the aerobic filter bed tank 108 to the upper part of the first anaerobic filter bed tank 104, a return pipe 122 for returning the supernatant water of the treated water is disposed. Then, the supernatant water pumped up from the aerobic filter bed tank 108 by the lift pipe 123 is sent to the sewage treatment apparatus D ₁ through the diversion metering device 124 and the return pipe 122 and subjected to the phosphorus removal treatment, 1 Returned to the anaerobic filter bed tank 104.
[0046]
【The invention's effect】
In the invention described in claim 1, a sewage storage tank having one bottom wall and two sets of opposing side walls, and iron disposed in the sewage storage tank for removing the phosphoric acid in the sewage by precipitation. At least one set of electrodes for eluting ions or aluminum ions by electrolysis, a power source for supplying electrolysis current to the electrodes, and a circulating water flow for circulating sludge accumulated in the sewage storage tank in the tank A pair of opposing side walls in the sewage storage tank, each of which is provided with an inclined portion for depositing sludge near the center of the bottom wall or guiding the sludge upward through a circulating water flow. A generating means is a blower for supplying compressed air arranged outside the tank, an air supply pipe connected to the blower for supplying compressed air, and connected to the air supply pipe and arranged at the bottom of the tank, and supplied. Compressed air Comprising a diffusing pipe for blowing from the number of spray holes obliquely downward. According to such a configuration, part of the sludge in the sewage is suspended in the sewage without accumulating due to the circulating water flow generated by the water flow generating means, and the inclined portion on one side wall is sludge. Has a function of guiding and depositing so as to slide down to the vicinity of the center of the bottom wall, and an inclined portion on the other side wall has a function of guiding the sludge deposited near the center of the bottom wall again by the circulating water flow. Therefore, the sludge in the sewage can easily flow out of the tank through the sewage outflow pipe provided on the side wall of the sewage storage tank, preventing electrical continuity and passivation due to the accumulated sludge. It becomes possible to remove phosphoric acid therein stably and reliably.
[0047]
According to the invention described in claim 2, the bottom wall is provided with an inclined portion for guiding the sludge accumulated in the sewage storage tank from one inclined portion to the other inclined portion of the pair of opposing side walls. . Accordingly, the sludge guided so as to slide down one inclined portion of the side wall is further guided so as to slide down the inclined portion of the bottom wall, and accumulates near the bottom wall of the other inclined portion of the side wall. Therefore, the sludge guide upward by the circulating water flow thereafter becomes easier, and the effect according to the invention of claim 1 can be more reliably exhibited.
[0048]
According to invention of Claim 3, an electrode is distribute | arranged substantially parallel with respect to the line which connects the sewage inflow part and sewage outflow part in a sewage storage tank, and an air diffuser pipe connects a sewage inflow part and a sewage outflow part. It is arranged to generate a circulating water flow in a direction almost parallel to the line. Accordingly, the sewage flowing into the sewage storage tank rides on a circulating water flow that smoothly flows 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 from the air rides on the circulating water stream and can efficiently clean the electrode surface. Further, when the sludge in a suspended state comes close to the sewage outflow part, it easily flows out of the tank through the sewage outflow part.
[0049]
According to the fourth aspect of the present invention, the blowout holes of the air diffuser are provided directly under the electrodes and in groups of two per set of electrodes. It is open toward. Therefore, it is possible to prevent the blowout holes from being blocked by the sludge that settles, and by the air blown out from the blowout holes provided in a set immediately below the electrodes and in pairs, It becomes possible to efficiently clean the necessary part of the electrode surface in the sewage, and furthermore, the necessary part of the electrode surface can be washed 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;
4 is an enlarged plan view showing a part of an air diffuser constituting the sewage treatment apparatus of FIG. 1; FIG.
FIG. 5 is a front sectional view of the air diffusing tube of FIG. 4;
6 is a structural explanatory view of the inside of a merged treatment septic tank in which the sewage treatment apparatus of FIG. 1 is incorporated, as viewed from the front.
7 is a structural explanatory view of the inside of the merged processing 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 part 6 Side wall 6a Inclined part 7 Side wall 7a Inclined part 8 Side wall 9 Side wall 10 Sewage inflow pipe 11 Sewage outflow pipe 13 Blower (water flow generating means)
14 Air supply pipe (water flow generation means)
15 Air diffuser (water flow generation means)
15a outlet (water flow generating means)
101 Small merger treatment septic tank

Claims (4)

A sewage storage tank having one bottom wall and two sets of opposing side walls, and at least eluting iron ions or aluminum ions disposed in the sewage storage tank for precipitating and removing phosphoric acid in the sewage by electrolysis A set of electrodes, a power source for supplying electrolysis current to the electrodes, and water flow generating means for generating a circulating water flow for circulating the sludge accumulated in the sewage storage tank in the tank,
A pair of opposing side walls in the sewage storage tank are provided with inclined portions for depositing sludge near the center of the bottom wall or guiding it upward by a circulating water flow at the lower part thereof,
A water flow generating means is a blower for supplying compressed air arranged outside the tank, an air supply pipe connected to the blower for supplying compressed air, and connected to the air supply pipe and arranged at the bottom of the tank, A sewage treatment apparatus comprising a diffuser pipe for blowing the supplied compressed air obliquely downward from a plurality of blowing holes. The sewage treatment apparatus according to claim 1, wherein an inclined portion is provided on the bottom wall for guiding the sludge accumulated in the sewage storage tank from one inclined portion to the other inclined portion of the pair of opposing side walls. The electrode is arranged almost parallel to the line connecting the sewage inflow part and the sewage outflow part in the sewage storage tank, and the diffuser pipe is circulated in the direction almost parallel to the line connecting the sewage inflow part and the sewage outflow part. The sewage treatment apparatus according to claim 1 or 2, which is arranged to generate water. 4. The blowout holes of the air diffuser are provided directly under the electrodes and in pairs, and each of the two pairs of blowout holes opens obliquely downward and inward. The sewage treatment apparatus as described.

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