JPH07108263A - Treatment of phosphorus containing water - Google Patents

Abstract

PURPOSE:To recover the function of a dephosphorization agent and to utilize backwash drainage by backwashing the dephosphorization agent with its function deteriorated after treatment of phosphorus containing water to recover its phosphorus adsorption function by peeling off its surface layer, and feeding the separated material to a wastewatexr treatment facility. CONSTITUTION:When a dephosphorization agent in a dephosphorization tower 5 is deteriorated, pumps P1, P2 is stopped and a pump P3 is actuated so that water to be treated in a backwash pump tank 6 is fed countercurrentwise to the tower 5 through a piping 21. The dephosphorization agent is backwashed, its surface layer being peeled off, to expose its new surface. The backwash drainage containing the separated material in the backwashing is returned to a flow control tank 1 through a piping 22.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for treating phosphorus-containing water, and in particular, phosphorus-containing water discharged from a sewage treatment apparatus is passed through a dephosphorizing agent-filled layer mainly composed of iron hydroxide. The present invention relates to a method for treating phosphorus-containing water that adsorbs and removes phosphorus to treat the phosphorus-containing water to restore the function of the dephosphorizing agent having reduced dephosphorization performance.

[0002]

2. Description of the Related Art In recent years, in closed water areas such as the Seto Inland Sea, Lake Biwa and Kasumigaura, deterioration of water quality due to eutrophication phenomenon has been further promoted, and obstacles to water utilization have increased, which has become a major social problem. The causative substances are said to be nitrogen and phosphorus, and in particular, the removal of phosphate ions in wastewater has become an important issue to be solved immediately.

Conventionally, as a method of removing phosphorus in water, there is a method of using a dephosphorizing agent containing iron hydroxide (iron oxide hydrate) as a main component, and various kinds of dephosphorizing agents have been proposed. This method utilizes the phenomenon that iron hydroxide adsorbs phosphorus in water, and is generally carried out by passing phosphorus-containing water through a dephosphorization tower or dephosphorization tank filled with a granular dephosphorization agent. Has been done.

[0004]

The use of the dephosphorizing agent causes the dephosphorizing performance to decrease with time. The dephosphorizing agent whose dephosphorizing performance is deteriorated needs to be replaced with a new dephosphorizing agent.

However, conventionally, no proposal has been made for a method for recovering the function of a dephosphorizing agent having a reduced dephosphorizing performance.

The present invention has been made in view of the above-mentioned conventional circumstances, and recovers the function of the dephosphorizing agent by treating the phosphorus-containing water to backwash the dephosphorizing agent having a reduced dephosphorizing performance. It is an object of the present invention to provide a method for treating phosphorus-containing water that improves the dephosphorization efficiency and reduces the dephosphorization cost by effectively reusing the backwash wastewater obtained at this time.

[0007]

According to a first aspect of the present invention, there is provided a method for treating phosphorus-containing water, wherein phosphorus-containing water discharged from a sewage treatment apparatus is passed through a dephosphorizing agent-filled layer mainly containing iron hydroxide. In the method for treating phosphorus-containing water for adsorbing and removing phosphorus, the function of the phosphorus-removing agent is recovered by treating the phosphorus-containing water by backwashing the phosphorus-removing agent having a reduced dephosphorization performance, and the surface of the phosphorus-removing agent is removed. The stripped material is returned to the sewage treatment apparatus to dephosphorize the sewage in the sewage treatment apparatus.

A method for treating phosphorus-containing water according to a second aspect is the same as the method for treating phosphorus-containing water according to the first aspect, wherein the dephosphorizing agent is backwashed with dephosphorized water, and the backwash drainage containing the peeled material is The raw water tank, the flow rate adjusting tank, the contact aeration tank, the aeration tank, the sedimentation tank, the sludge thickening tank, the sludge thickening storage tank, or any one of the tanks of the sludge thickening tank or its inflow pipe is fed.

That is, as a result of various studies on the backwashing of the dephosphorizing agent, the present inventor has found that the dephosphorizing agent causes a minute amount of peeling on the surface due to the mechanical impact applied during the backwashing, which results in the phosphorus adsorption ability. It was found that the surface having γ was newly exposed to recover the phosphorus adsorption performance, and that the exfoliated product generated at this time still had some dephosphorization performance. Then, the function recovery of the dephosphorizing agent by the backwashing and the effective use of the exfoliated material having the dephosphorizing performance were repeatedly studied, and the present invention was completed.

It is important that the dephosphorizing agent mainly composed of iron hydroxide used as the dephosphorizing agent in the present invention has such strength that a part of the surface is peeled off by backwashing.

There is no particular limitation on such a dephosphorizing agent, but it is preferable that the present applicant previously filed Japanese Patent Application No. 5-1418.
It is preferable to use the one produced by the method proposed in No. 60.

That is, those obtained by the following method or are preferable.

An iron hydroxide precipitate obtained by neutralizing an aqueous solution containing iron ions is dried at a product temperature of 120 ° C. or lower to obtain a semi-dried product having a water content of 20 to 50% without reducing the water content to less than 20%. The semi-dried product is granulated and then dried at a product temperature of 120 ° C or lower.

An iron hydroxide precipitate obtained by neutralizing an aqueous solution containing iron ions is dried at a product temperature of 120 ° C. or lower to give a dried product having a water content of less than 20%.
Granulation is performed for 5 minutes or more by a centrifugal tumbling type or centrifugal tumbling flow type granulator while spraying water of 300 μm, and then the granulated product is dried at a product temperature of 120 ° C. or less.

According to such a method, it is possible to obtain a granulated product having sufficient strength from iron hydroxide alone, without using an auxiliary raw material for ensuring strength.

The particle size of such a dephosphorizing agent is preferably about 0.3 to 10 mm in terms of handleability and dephosphorizing efficiency, and its breaking strength is 8 to 40 kgD.
It is preferably about WL from the viewpoint of handleability and backwashing effect.

As the dephosphorizing agent, one obtained by curing iron hydroxide with an unsaturated polyester resin or polyurethane resin can be used, but one having a large proportion of the curing agent and having excessively high strength is used. Since the surface cannot be peeled off by backwashing, the effect of the present invention cannot be obtained. Therefore, it is important to use a cured product so that the surface can be peeled off.

To pass the phosphorus-containing water discharged from the sewage treatment apparatus through the dephosphorizing agent-packed bed, for example, the phosphorus-removing tower or the dephosphorization tank in which the dephosphorizing agent is packed is formed. The contained water may be passed upward or downward.

Further, in order to backwash the dephosphorizing agent whose dephosphorizing performance is lowered by the treatment of the phosphorus-containing water, for example, the dephosphorizing column filled with the dephosphorizing agent is washed with upflow washing water (in the usual case, Dephosphorized water is used.)

The backwashing may be backwashing with air, or backwashing with water and air, instead of backwashing with water.

[0021]

The present inventor treated the phosphorus-containing water to backwash the dephosphorizing agent having a reduced dephosphorizing performance and peeling the surface of the dephosphorizing agent by a mechanical impact, so that the surface having the phosphorus adsorbing ability can be improved. It was newly found that the phosphorus adsorption performance of the dephosphorizing agent can be recovered and that the dephosphorized agent exfoliation product obtained by such backwashing of the dephosphorizing agent still has the adsorption ability. .

Therefore, by feeding the dephosphorized product exfoliated material to the raw water tank, the flow rate adjusting tank, the aeration tank, the contact aeration tank, the sedimentation tank, the coagulation treatment tank, the coagulation sedimentation tank, etc. of the sewage treatment apparatus,
Phosphorus in raw water can be removed by adsorption. Then,
The removed product of the dephosphorizing agent that has adsorbed phosphorus is taken into sludge and efficiently discharged out of the system.

[0023] Further, when the removed substances of the dephosphorizing agent are returned to the sludge thickening tank and the sludge storage tank, the effect of suppressing the generation of scum can be obtained together with the adsorption and removal of phosphorus. It is presumed that the mechanism of the effect of suppressing the generation of scum by the exfoliated substance of the dephosphorizing agent is due to the aggregating action of sludge by the iron hydroxide, which is the main component of the dephosphorizing agent, and the precipitation action due to its large specific gravity.

[0024]

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

FIGS. 1 to 3 are system diagrams showing a method of treating phosphorus-containing water according to an embodiment of the present invention.

In the method shown in FIG. 1, a biological sewage treatment apparatus by a contact aeration method is used as a sewage treatment apparatus, and phosphorus-containing water discharged from the sewage treatment apparatus is removed by forming a packing layer of a dephosphorizing agent. It is processed in a phosphorus tower.

That is, the raw water is supplied from the pipe 11 to the flow control tank 1
Is introduced into the contact aeration tank 2 through the pipe 12 equipped with the pump P ₁ and treated for aerobic organisms. The outflow water of the contact aeration tank 2 is introduced into the precipitation tank 3 through the pipe 13, and the supernatant water is passed through the pipe 14, the dephosphorization pump tank 4 and the pipe 15 equipped with the pump P ₂ to the dephosphorization tower 5 for the dephosphorization treatment. The water is discharged through the pipe 16, the backwash pump tank 6 and the pipe 17. On the other hand, the separated sludge in the settling tank 3 is extracted from the pipe 18, and after the desorbed liquid is separated in the sludge concentration storage tank 7, it is carried out from the pipe 19. The desorbed liquid in the sludge thickening storage tank 7 is returned to the flow rate adjusting tank 1 through the pipe 20. 1
A and 2A are aeration tubes, 2B is a biofilm, and 5A is a dephosphorizing agent packed bed.

In the present embodiment, in such biological wastewater treatment and dephosphorization treatment, when the dephosphorization performance of the dephosphorization agent in the dephosphorization tower 5 deteriorates, the pumps P ₁ and P ₂ are stopped, By operating the pump P ₃ , the dephosphorized water in the backwash pump tank 6 is passed through the pipe 21 to the dephosphorization tower 5 in an upward flow to backwash the dephosphorizing agent. Then, the backwash drainage discharged from the dephosphorization tower 5 and containing the dephosphorized agent peeled off by the backwash is returned to the flow rate adjusting tank 1 through the pipe 22.

As mentioned above, since the exfoliated product of the dephosphorizing agent still has the dephosphorization performance, the exfoliated product of the dephosphorizing agent in the backwash drainage returned to the flow rate adjusting tank 1 is the flow adjusting tank. Adsorbs phosphorus in raw water in 1.

The dephosphorization agent exfoliated material introduced into the flow rate adjusting tank 1 is in the form of fine particles and has a slow sedimentation rate, but the process of sequentially flowing into the contact aeration tank 2 and the precipitation tank 3 together with the raw water. At that time, it is taken in and removed from the activated sludge and is carried out of the system as sludge, so the phosphorus in the raw water is removed.

In the method of this embodiment, the same effect can be obtained by returning the backwash drainage to the contact aeration tank 2 or the precipitation tank 3 in addition to the flow rate adjusting tank 1. Further, by returning to the sludge thickening storage tank 7, removal of phosphorus re-released from sludge in the sludge thickening storage tank 7 and prevention of scum generation are prevented, and the phosphorus concentration of the desorbed liquid returned to the flow rate adjusting tank 1 is prevented. Also, the SS and BOD concentrations can be reduced.

In the method shown in FIG. 2, a biological sewage treatment apparatus using a standard activated sludge method is used as a sewage treatment apparatus, and phosphorus-containing water discharged from this sewage treatment apparatus is used to form a packed bed of a dephosphorizing agent. It is processed in a dephosphorization tank.

That is, the raw water is supplied from the pipe 41 to the flow rate adjusting tank 3
1 is introduced into the aeration tank 32 through a pipe 42 equipped with a pump P ₄ and treated for aerobic organisms. The outflow water of the aeration tank 32 is introduced into the settling tank 33 through the pipe 43, the supernatant water is passed through the pipe 44 to the dephosphorization tank 34, and the dephosphorized water is passed through the pipe 45, the backwash pump tank 35 and the pipe 46. After that, it is released. On the other hand, the sludge separated in the settling tank 33 is pipe 47.
Further, a part is returned to the aeration tank 32 through the pipe 48, and the rest is supplied to the sludge concentration tank 36 through the pipe 49. The desorbed liquid separated in the sludge thickening tank 36 is returned to the aeration tank 32 through the pipe 50, and the separated sludge is carried out of the system through the pipe 51, the sludge storage tank 37, and the pipe 52. 3
1A and 32A are aeration pipes, and 34A is a dephosphorizing agent packed bed.

In this embodiment, when the dephosphorization performance of the dephosphorizing agent in the dephosphorization tank 34 deteriorates in such biological wastewater treatment and dephosphorization treatment, the pump P ₄ is stopped and the pump P ₅ Is operated, and the dephosphorized water in the backwash pump tank 35 is passed through the pipe 53 to the dephosphorization tank 34 in an upward flow to backwash the dephosphorizing agent. And dephosphorization tank 3
The backwash drainage discharged from No. 4 containing the dephosphorized agent peeled off by the backwash is returned to the sludge concentrating tank 36 through the pipe 54.

As described above, since the exfoliated product of the dephosphorizing agent still has the dephosphorizing performance, the exfoliated product of the dephosphorizing agent in the backwash drainage returned to the sludge concentrating tank 36 is the sludge concentrating tank. Phosphorus in the liquid water in 36 is adsorbed and effectively acts on the removal of phosphorus in the system.

That is, although the activated sludge has a small amount of ability to take up phosphorus, when the activated sludge containing this phosphorus flows into the sludge thickening tank 36 and becomes anaerobic, it releases the taken up phosphorus. Therefore, the phosphorus concentration of the desorbed liquid increases. When the desorbed liquid having an increased phosphorus concentration is returned to the flow rate adjusting tank 31, phosphorus is circulated in the system and phosphorus is not removed.

However, as in this example, by feeding the backwash drainage containing the dephosphorized agent exfoliated material to the sludge thickening tank,
The phosphorus adsorption action of the exfoliated substance of the dephosphorizing agent can prevent the phosphorus concentration of the desorbed liquid from increasing due to the release of phosphorus from the activated sludge. Then, the removed substance of the dephosphorizing agent that has adsorbed phosphorus is taken into sludge and discharged to the outside of the system, so that phosphorus in the system can be efficiently removed.

In the sludge thickening tank 37, normally, scum is generated, and the return of the scum to the flow rate adjusting tank 31 together with the desorbed liquid causes increase in SS and BOD in the system. The addition of backwash drainage prevents the generation of such scum due to the agglomeration and precipitation effects of the dephosphorization agent mainly composed of iron hydroxide, which has a large specific gravity, and also prevents SS and BOD in the system. Will be reduced.

In this embodiment, the sludge thickening tank may be a sludge thickening storage tank. Further, also in the method of this embodiment, by returning the backwash drainage to the flow rate adjusting tank 31, the aeration tank 32, or the precipitation tank 33, the same dephosphorization effect as in the embodiment shown in FIG. 1 can be obtained. it can.

In the method shown in FIG. 3, a coagulation sedimentation treatment device is used as a sewage treatment device, and the phosphorus-containing water discharged from this sewage treatment device is treated in a dephosphorization tower having a dephosphorizing agent packed bed. Is.

That is, the raw water is coagulated from the pipe 61 through the first coagulation tank 62 and the second coagulation tank 63, the coagulated water is separated from the pipe 64 by the sedimentation tank 65, and the supernatant water is separated from the pipe 66. Further, water is passed to the dephosphorization tower 67 for treatment. This treated water is discharged from the pipe 68. Settling tank 65
The separated sludge is discharged from the pipe 69. 62A, 63A
Is a stirrer, and 67A is a dephosphorizing agent packed bed.

In the present embodiment, when the dephosphorization performance of the dephosphorization agent in the dephosphorization tower 67 deteriorates in such coagulation sedimentation treatment and dephosphorization treatment, the feed of raw water is stopped and the backwash water is washed. Water is passed upward from the pipe 69 to the dephosphorization tower 67 to backwash the dephosphorization agent. Then, the backwash drainage containing the dephosphorized agent exfoliated matter discharged from the dephosphorization tower 67 is pipe 70.
It is returned to the first aggregation treatment tank 62.

In this way, by returning the backwash drainage of the dephosphorization tower 67 to the first coagulation tank 62, the exfoliation product of the dephosphorization agent adsorbs the phosphorus contained in the raw water, and the exfoliation adsorbing the phosphorus. The substance is taken into the sludge in the settling tank 65 through the second coagulating tank 63, coagulated and separated by separation, and discharged to the outside of the system, so that the phosphorus in the raw water is removed.

Also in this embodiment, the backwashing waste water may be sent to the second flocculation treatment tank 62 or the second flocculation treatment tank or the precipitation tank 65, and the same phosphorus removing effect can be obtained. .

The embodiments shown in FIGS. 1 to 3 are all embodiments of the present invention, and the present invention is not limited to the illustrated embodiments unless the gist thereof is exceeded. .
For example, the tank configuration of each sewage treatment apparatus is not particularly limited, and the backwash drainage may be returned to any tank of the sewage treatment apparatus or its inflow pipe.

The present invention will be described in more detail below with reference to experimental examples. The dephosphorizing agent used in the experimental example is manufactured as follows.

That is, first, caustic soda was added to a 10 wt% iron sulfate aqueous solution to adjust the pH to 7, and the obtained iron hydroxide precipitate was dehydrated with a filter press to a water content of 61%, and then the dehydrated cake was kneaded in a mixer. Moisture content 38% under reduced pressure at 90 ℃
It was semi-dried. The obtained semi-dried product was subjected to centrifugal tumbling fluidized granulator so that 90% or more of the particles had a particle size of 1-2.
The particles were granulated to have a size in the range of mm. Next, the granulated product is air-dried for 2 days at room temperature to a moisture content of about 5%, and the fracture strength of iron hydroxide is 29 kg DW.
L dephosphorizer was obtained.

Experimental Example 1 Using a dephosphorizing agent in which phosphorus was adsorbed to a saturated adsorption amount to reduce the phosphorus adsorption performance, the recovery of the phosphorus adsorption performance by backwashing was examined.

First, two transparent vinyl chloride columns (diameter 16 mm) were filled with a dephosphorizing agent (filling amount 26
ml, filling height 130 mm), 28 mg-P / l Na
_{The 2} HPO ₄ aqueous solution was passed through with a downflow at SV = 10 hr ⁻¹ for 6 days. After flowing for 6 days, the phosphorus concentration in the runoff is 25m
It became g-P / l, and it was confirmed that the phosphorus adsorption performance of the dephosphorizing agent was almost lost.

One of the two columns (N
o. For 1), water was backwashed by flowing in an upward flow. By this backwashing with water, the dephosphorizing agents collided with each other and their surfaces were peeled off, and thus the resulting backwashing wastewater was colored red due to the exfoliated substances on the surface of the dephosphorizing agent having adsorbed phosphorus.

For the other column (No. 2), water was passed in a downward flow to extrude the Na ₂ HPO ₄ aqueous solution in the column.

Na ₂ H was applied to each column under the same conditions as above.
The PO ₄ aqueous solution was passed again, and the time-dependent change in the phosphorus concentration of the outflow water was examined. The results are shown in FIG.

From FIG. 4, the surface of the dephosphorization agent is peeled off by the mechanical impact applied by the backwashing, and the surface is renewed and the surface having the phosphorus adsorption performance is newly exposed. It can be seen that the adsorption performance of the phosphorus agent is restored.

On the other hand, in the case of extruding with water without backwashing (No. 2), the function of the dephosphorizing agent is still low, and the phosphorus concentration of the outflow water is high.

This No. N including 1 column
o. In the second column, the phosphorus concentration in the outflow water is low at the initial stage of water flow because the backwash water or the extrusion water originally contained in the column flows out.

Experimental Example 2 It was investigated that the exfoliated material on the surface of the dephosphorizing agent contained in the backwash drainage has a dephosphorizing performance.

Using the house drainage having the water quality shown in Table 1 as raw water, a part of the backwash drainage obtained in Experimental Example 1 (water quality is as shown in Table 1) was used as raw water: backwash drainage = 9: The mixture was mixed at a ratio of 1 (volume ratio), the water quality of the mixed water was examined, and the results are shown in Table 1.

[0058]

[Table 1]

The following is clear from Table 1.

That is, PO ₄ of mixed water of raw water and backwash drainage
^3-- P concentration is about 2.7 mg when calculated from the mixing ratio.
/ L (≈3.0 × 0.9), but actually it is significantly reduced to 0.5 mg / l, and phosphorus has been removed by the stripping agent of the dephosphorizing agent. I understand. In addition, since this mixed water does not remove the precipitate, T
-P concentration is a calculated value (4.0 x 0.9 + 14 x 0.1 =
It is a value equal to 5.0). That is, since the exfoliated product of the dephosphorizing agent is in the form of fine particles and has a slow sedimentation rate, no change is observed in the T-P concentration.

From this result, the backwash drainage containing the dephosphorized product was taken from the raw water side of the sewage treatment equipment (raw water tank, flow control tank,
It can be seen that the wastewater in the wastewater treatment device can be dephosphorized by returning it to the sedimentation tank.

Experimental Example 3 It was investigated that the exfoliated substance of the dephosphorizing agent contained in the backwash drainage has a dephosphorizing performance and that the exfoliated substance is taken in and removed by the activated sludge.

The activated sludge mixed liquid (collected from the aeration tank of the standard activated sludge method. The quality of the supernatant water obtained by standing for 60 minutes is shown in Table 2) was used as the raw water and obtained in Experimental Example 1. A part of the backwash drainage (the water quality of the supernatant water obtained by standing for 60 minutes is shown in Table 2) is thoroughly stirred and mixed at a ratio of raw water: backwash drainage = 9: 1 (volume ratio). The resulting supernatant water (hereinafter referred to as "mixed supernatant water") was allowed to stand for 60 minutes.
The water quality was investigated and the results are shown in Table 2.

[0064]

[Table 2]

The following is clear from Table 2.

That is, the T-P concentration and the PO ₄ ³ --P concentration obtained by calculation from the mixing ratio of the raw water and the backwash drainage are respectively T-P = 4 × 0.1 + 2.8 × 0.9 ≒ 2.9m
g / l, PO ₄ ^3-- P≈2.5 × 0.9≈2.25 mg
/ L, but the resulting mixed supernatant water had a T-P of 0.3.
mg / l, a ^{_{PO 4 3- -P = 0.1mg / l}} , by mixing the backwash effluent, it is clear that phosphorus is removed.

For SS, the calculated value is 13.9 m.
g / l (= 49 × 0.1 + 10 × 0.9) is SS = 10 mg / l in the mixed supernatant water, and SS (exfoliation product of dephosphorizing agent) in the backwash drainage is the activated sludge mixed liquid. It can be seen that by mixing with, it was taken in and removed from the activated sludge.

From this result, by returning the backwash waste water containing the dephosphorized agent exfoliated product to the tank (contact aeration tank, aeration tank, sedimentation tank, etc.) containing the activated sludge of the sewage treatment apparatus, the sewage was dephosphorized. It can be seen that it is possible to separate and remove the exfoliated substances of the dephosphorizing agent in the backwash drainage containing phosphorus.

Experimental Example 4 It was investigated that the exfoliated product of the dephosphorizing agent contained in the backwash drainage has a dephosphorizing performance and has a scum generation inhibiting effect.

Excess sludge (excess sludge of the activated sludge method, scum floats when left standing for 2 days. The quality of intermediate water at the bottom of the scum is as shown in Table 3) was used as the original sludge.
Part of the backwash drainage obtained in (the water quality of the supernatant water after standing for 2 days is as shown in Table 3) is the ratio of raw sludge: backwash drainage = 1: 1 (volume ratio) Table 3 shows the water quality of the supernatant water (hereinafter referred to as "mixed supernatant water") obtained by allowing the mixture to stand for 2 days.

[0071]

[Table 3]

The following is clear from Table 3.

That is, since phosphorus is released from the original sludge (excess sludge), the phosphorus concentration of the intermediate water obtained by allowing the excess sludge to stand is considerably high. Then, the T-P concentration and PO ₄ ³ --calculated from the mixing ratio of the raw sludge and the backwash drainage are calculated.
The P concentration is TP = 54 × 0.5 + 2 × 0.
_{5 = 28mg / l, PO 4} 3- -P ≒ 20 × 0.5 = 10
mg / l, but the obtained mixed supernatant water had T-P = 4 m
g / l, a ^{_{PO 4 3- -P = 3mg / l}} , by mixing the backwash effluent, it is clear that re-adsorption and removal of released phosphate is made.

In the intermediate water of the original sludge (excess sludge), SS = 100 mg / l and BOD = 20 due to the floating of scum.
It is 0 mg / l, which is extremely high. However, in the mixed supernatant water, by mixing the backwash drainage, SS, BOD
It can be seen that both are significantly reduced and the occurrence of scum is suppressed.

From this result, by returning the backwash wastewater containing the dephosphorized agent exfoliated product to the sludge concentration tank, the sludge concentration storage tank, etc. of the sewage treatment apparatus, it is possible to prevent the generation of scum and the increase of the phosphorus concentration due to the release of phosphorus. You can see that you can.

[0076]

As described in detail above, according to the method for treating phosphorus-containing water of the present invention, the phosphorus-containing water discharged from the sewage treatment apparatus is passed through the dephosphorizing agent-filled layer mainly containing iron hydroxide. In the treatment method of phosphorus-containing water that removes phosphorus by adsorption with water, by effectively using the exfoliated product of the dephosphorization agent obtained by backwashing the dephosphorization agent, the treatment efficiency of the sewage treatment apparatus in the first stage is increased,
It is possible to efficiently and inexpensively obtain treated water of high quality.

[Brief description of drawings]

FIG. 1 is a system diagram showing a method of an embodiment of a method for treating phosphorus-containing water of the present invention.

FIG. 2 is a system diagram showing another embodiment method of the phosphorus-containing water treatment method of the present invention.

FIG. 3 is a system diagram showing another embodiment method of the phosphorus-containing water treatment method of the present invention.

FIG. 4 is a graph showing the results of Experimental Example 1.

[Explanation of symbols]

 1,31 Flow rate adjusting tank 2 Contact aeration tank 3,33,65 Precipitation tank 4 Dephosphorization pump tank 5,67 Dephosphorization tower 6,35 Backwash pump tank 7 Sludge concentration storage tank 32 Aeration tank 34 Dephosphorization tank 36 Sludge concentration tank 37 Sludge storage tank 62 First coagulation treatment tank 63 Second coagulation treatment tank

Claims (2)

[Claims] 1. A method for treating phosphorus-containing water, wherein phosphorus-containing water discharged from a sewage treatment apparatus is passed through a dephosphorizing agent-packed layer mainly containing iron hydroxide to adsorb and remove phosphorus. By removing the dephosphorizing agent whose dephosphorizing performance is reduced by backwashing the surface of the dephosphorizing agent,
A method for treating phosphorus-containing water, comprising recovering the function of a dephosphorizing agent, returning the exfoliated material on the surface of the dephosphorizing agent to the sewage treatment apparatus to dephosphorize the sewage in the sewage treatment apparatus. . 2. The method for treating phosphorus-containing water according to claim 1, wherein the dephosphorizing agent is back-washed with de-phosphorized water, and the back-washing waste water containing the peeled material is adjusted to a raw water tank of the waste water treatment device and a flow rate adjustment. A method for treating phosphorus-containing water, which comprises feeding to any one of a tank, a contact aeration tank, an aeration tank, a precipitation tank, a sludge thickening tank, and a sludge thickening storage tank, or an inflow pipe thereof.