JP3879136B2 - Dephosphorization equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a dephosphorization apparatus, and in particular, dephosphorization treatment of organic waste water to efficiently produce magnesium ammonium phosphate (MgNH ₄ PO ₄ .6H ₂ O, hereinafter referred to as MAP) useful as a fertilizer. It relates to phosphorus equipment.
[0002]
[Prior art]
Conventionally, MAP that is effectively used as a fertilizer is manufactured using surplus sludge generated in anaerobic and aerobic treatment processes such as sewage, human waste, and wastewater as a raw material. Specifically, these excess sludges are anaerobically digested, and then undigested sludge is dehydrated and separated, and magnesium salt is added to the separation liquid produced at that time. That is, when excess sludge is digested in an anaerobic digester, the excess sludge is digested and decomposed, and phosphorus in the sludge is released into the liquid. Therefore, since the separation liquid (digestion detachment liquid) obtained by separating undigested sludge from the digestion treatment liquid has a high phosphorus concentration and is suitable as a raw material for MAP, a magnesium salt is added to this separation liquid, To precipitate.
[0003]
[Problems to be solved by the invention]
The conventional method has the following problems due to anaerobic digestion.
[0004]
(1) A large anaerobic digester is required.
(2) It is difficult to dehydrate undigested sludge.
(3) The operation management of the anaerobic digester is complicated.
[0005]
The present invention solves the above-mentioned conventional problems and efficiently recovers and concentrates phosphorus from organic wastewater without anaerobic digestion, thereby efficiently producing MAP useful as a fertilizer. An object is to provide a phosphorus device.
[0006]
[Means for Solving the Problems]
The dephosphorization apparatus of the present invention includes a biological dephosphorization tank for biologically dephosphorizing phosphorus-containing water, a concentration means for concentrating excess sludge from the biological dephosphorization tank, and a concentrated sludge concentrated by the concentration means. An anaerobic tank that is a closed stirring tank for releasing phosphorus from the solid, a solid-liquid separation means for aggregating and dehydrating the treatment liquid from the anaerobic tank using a polymer flocculant, and water separated from the solid-liquid separation means And a dephosphorization tank for depositing magnesium ammonium phosphate by adding a magnesium salt .
[0007]
The excess sludge obtained by biological dephosphorization treatment contains phosphorus at a high concentration. However, if phosphorus is to be released directly from the excess sludge in an anaerobic tank, the phosphorus concentration in the sludge is insufficient and phosphorus cannot be released efficiently. If this excess sludge is concentrated in advance by a concentration means, phosphorus is released at a high concentration in an anaerobic tank. Accordingly, MAP can be efficiently generated by treating phosphorus released in the anaerobic tank in the dephosphorization tank to precipitate MAP.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the dephosphorization apparatus of the present invention will be described in detail with reference to the drawings.
[0009]
FIG. 1 is a system diagram showing an embodiment of the dephosphorization apparatus of the present invention.
[0010]
In the dephosphorization apparatus of the present embodiment, first, phosphorus-containing water is first subjected to solid-liquid separation in the sedimentation basin 1, and then the separated water is subjected to biological dephosphorization treatment in the biological dephosphorization treatment tank 2. As this biological dephosphorization processing tank 2, a general biological dephosphorization processing tank having an anaerobic process and an aerobic process can be used.
[0011]
The sludge separated in the first settling tank 1 is concentrated in the gravity concentration tank 4, and the separated water is returned to the first settling tank 1. On the other hand, the concentrated sludge is fed to the anaerobic tank 6 at the subsequent stage.
[0012]
The treated water in the biological dephosphorization processing tank 2 is fed to a solid-liquid separation means (for example, a sedimentation basin) 3 to separate sludge containing phosphorus, and the separated water is discharged out of the system as treated water. A part of the separated sludge is returned to the biological dephosphorization treatment tank 2 as return sludge, and the surplus sludge is fed to the concentration means 5 and concentrated.
[0013]
As the concentrating means 5, when phosphorus is released from the sludge during the concentration, the phosphorus recovery efficiency and the MAP generation efficiency are lowered. Therefore, a means that does not release phosphorus from the sludge is desirable. For example, a pressurized flotation means that maintains aerobicity, or centrifugal concentration and membrane concentration means that can concentrate in a short time are suitable.
[0014]
The sludge concentrated by the concentration means 5 is fed to the anaerobic tank 6 together with the concentrated sludge in the gravity concentration tank 4. The anaerobic tank 6 is a dense closed stirred tank.
[0015]
The residence time of the anaerobic tank 6 is not particularly limited as long as phosphorus is sufficiently released from the concentrated sludge, but is preferably 1 day or longer.
[0016]
The processing liquid in the anaerobic tank 6 is then fed to the solid-liquid separation means 7 for solid-liquid separation. The solid-liquid separation means 7 is preferably a means for aggregating using a polymer flocculant without using an inorganic flocculant and dehydrating with a belt press or a centrifuge.
[0017]
The dehydrated cake obtained by the solid-liquid separation means is discharged out of the system.
[0018]
On the other hand, the separated water is fed to the dephosphorization tank 8. In the dephosphorization tank 8, a magnesium salt is added, and phosphorus is precipitated as MAP. The magnesium salt is not particularly limited, and MgCl ₂ , Mg (OH) ₂ , MgSO ₄ , other seawater, and the like can be used. The amount added is preferably equimolar or more with phosphorus in the separated water.
[0019]
By using a granulation tank as the dephosphorization tank 8, and adding alkali as necessary and treating at pH 8-9, granular MAP can be precipitated, and MAP can be easily separated and recovered. Moreover, the handleability as a fertilizer is also improved, which is preferable.
[0020]
The MAP generated in the dephosphorization tank 8 is collected and fed to a commercialization process as a fertilizer. On the other hand, the separated water is first returned to the settling basin.
[0021]
In the present invention, examples of the phosphorus-containing water used for the biological dephosphorization treatment include organic wastewater such as sewage, human waste, and food wastewater.
[0022]
【Example】
Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples.
[0023]
Example 1
Excess sludge was extracted from the sedimentation basin from the equipment that was treating sewage by the biological dephosphorization method (anaerobic-aerobic method). The MLSS concentration of this sludge was 5200 mg / L, and the phosphorus content was 4.1% by weight per MLSS.
[0024]
500 mL of this sludge was concentrated by centrifugation at 3000 rpm for 1 minute. As a result, the MLSS concentration was 6.5% by weight. This concentrated sludge was left in a 100 mL measuring cylinder for 24 hours. As a result, 1310 mg / L of phosphorus was released into the liquid. After adding 3.0 wt% of a cationic polymer (“CLIFIX CP-604” manufactured by Kurita Kogyo Co., Ltd.) to this solution and stirring, Filter with 5A filter paper. The obtained filtrate contained 1280 mg / L of phosphorus.
[0025]
Magnesium sulfate was added to this filtrate so that it might become 10,000 mg / L, pH was adjusted to 8.5 with sodium hydroxide, and it stirred slowly for 4 hours. As a result, 0.9 g of MAP could be recovered.
[0026]
Comparative Example 1
In Example 1, when the same treatment was performed except that the excess sludge was not concentrated, the recovered amount of MAP was 0.06 g.
[0027]
【The invention's effect】
As described in detail above, according to the dephosphorization apparatus of the present invention, phosphorus is efficiently recovered and concentrated from organic wastewater without anaerobic digestion, and MAP useful as a fertilizer is efficiently produced. be able to.
[Brief description of the drawings]
FIG. 1 is a system diagram showing an embodiment of a dephosphorization apparatus of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 First sedimentation basin 2 Biological dephosphorization processing tank 3 Solid-liquid separation means 4 Gravity concentration tank 5 Concentration means 6 Anaerobic tank 7 Solid-liquid separation means 8 Dephosphorization tank

Claims (1)

A biological dephosphorization tank for biologically dephosphorizing phosphorus-containing water;
A concentration means for concentrating excess sludge from the biological dephosphorization tank;
An anaerobic tank which is a sealed stirring tank for releasing phosphorus from the concentrated sludge concentrated by the concentration means;
Solid-liquid separation means for aggregating and dehydrating the treatment liquid from the anaerobic tank using a polymer flocculant;
A dephosphorization apparatus comprising: a dephosphorization tank for adding magnesium salt to water separated from the solid-liquid separation means to precipitate magnesium ammonium phosphate.

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