JP2007313478A - Method for adsorbing/recovering phosphorous, phosphorous adsorbing/recovering device, and method for reutilizing recovered phosphorous - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To inexpensively perform purification of eutrophicated water by efficiently recovering phosphorous comprised in the eutrophicated water, and further, to effectively reutilize the recovered phosphorous. <P>SOLUTION: Eutrophicated water in a water region 12 as the object for purification is passed through the inside of a purifying/recovering device 10 installed in the outside of the system of the water region 12 as the object for purification and charged with coal ash 2 comprising hollow particles 1, thus phosphorous comprised in the eutrophicated water is adsorbed into the hollow particles 1 and is recovered to efficiently purify the eutrophicated water. In the case the hollow particles 1 reach an adsorption volume, what is necessary is to exchange only the coal ash 2 comprising the hollow particles 1 to the purifying/recovering device 10 installed in the outside of the system of the water region 12 as the object for purification. In this way, a dredging treatment is not required, thus waste sludge caused by dredging is not produced, and the treatment can be performed at a low cost. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for purifying and recovering phosphorus contained in eutrophication water, a device for purifying and recovering phosphorus, and a method for reusing recovered phosphorus.

  Conventionally, elution of phosphorus contained in eutrophic water is one of the water pollution factors in lakes, rivers and other closed water areas. As one of the methods for purifying eutrophication water by reliably adsorbing such phosphorus, an adsorbent such as zeolite is introduced into the eutrophication water, adsorbed the eutrophication component, and then stirred. There is a method of discharging outside the water system (for example, see Patent Document 1). In addition, there is a method in which a coal ash granulated material is laid on the bottom of a purification target water area such as a lake to adsorb phosphorus (for example, see Patent Document 2).

JP-A-9-310373 JP 2004-113985 A

  However, as shown in Patent Documents 1 and 2, when the zeolite is introduced or the bottom of the coal ash granule is laid, the adsorption effect disappears when the phosphorus adsorption capacity is reached. It is necessary to remove the adsorbent itself such as a granulated material, and there is a drawback that it costs labor costs. Moreover, it considers only the purification | cleaning of phosphorus with respect to eutrophication water, Comprising: Efficient collection | recovery of phosphorus and effective reuse of the collect | recovered phosphorus are not mentioned at all.

  The present invention has been made in view of the above, and is capable of efficiently recovering phosphorus contained in eutrophication water and purifying eutrophication water at low cost, and effectively recovering the recovered phosphorus. It is an object of the present invention to provide a phosphorus purification and recovery method that can be reused, a phosphorus purification and recovery device, and a method of recycling recovered phosphorus.

  In order to solve the above-described problems and achieve the object, a method for purifying and recovering phosphorus according to the present invention includes installing a purification and recovery device filled with coal ash containing hollow particles outside the system to be purified, It is characterized in that the eutrophication water in the water area to be purified is passed through the purification and recovery device so that phosphorus contained in the eutrophication water is adsorbed inside the hollow particles.

  The method for reusing recovered phosphorus according to the present invention is contained in coal ash filled in a purification and recovery device installed outside the purification target water area, and passes eutrophication water in the purification target water area. It is characterized in that used hollow particles that have received water and adsorbed phosphorus contained in the eutrophic water until the adsorption capacity is reached are used as agricultural fertilizers.

  The phosphorus purification and recovery apparatus according to the present invention includes a casing that is filled with coal ash containing hollow particles and is installed outside the purification target water area, and the eutrophication of the purification target water area within the casing. Water is passed through.

  According to the method for purifying and recovering phosphorus according to the present invention, the device for purifying and recovering phosphorus and the method for reusing recovered phosphorus, when hollow particles contained in coal ash are immersed in a phosphoric acid solution, phosphate ions are hollow particles. The adsorption mechanism of phosphorus adsorbing inside the hollow particles is found by passing through the outer shell gap and binding with the calcium inside, and coal ash containing hollow particles is installed outside the system to be purified. By allowing eutrophication water in the water to be purified to pass through the clarified purification / collection device, phosphorus contained in the eutrophication water is adsorbed inside the hollow particles and recovered to efficiently recover the eutrophication water. When the hollow particles reach the adsorption capacity, only the coal ash containing the hollow particles for the purification and recovery device installed outside the system to be purified needs to be replaced, and no soot treatment is required. It without the excess sludge by occurs, an effect that can be processed at low cost. In addition, the hollow particles contained in the coal ash that reaches the adsorption capacity and is exchanged does not contain sludge, has high phosphorus recovery efficiency, and can be effectively reused as an agricultural phosphorus fertilizer. Play.

  Embodiments of a phosphorus purification and recovery method, a phosphorus purification and recovery apparatus, and a method of reusing recovered phosphorus according to the present invention will be described below with reference to the drawings. The present invention is not limited to this embodiment, and various modifications can be made without departing from the spirit of the present invention.

  The phosphorus purification and recovery method and purification recovery apparatus of the present embodiment are based on using coal ash as an adsorbent for purifying and recovering phosphorus contained in eutrophication water. Here, the adsorption mechanism of phosphorus to coal ash when using coal ash will be described.

First, FIG. 3 is a schematic diagram showing a conventional mechanism of phosphorus adsorption. The conventional mechanism of phosphorus adsorption is that calcium Ca contained in coal ash dissolves as calcium ions Ca ²⁺ , binds to phosphate ions PO ₄ ²⁻ in the liquid, and becomes insoluble in the liquid as calcium phosphate CaPO _4. It is recognition. This mechanism of phosphorus adsorption is used for purifying phosphorus with respect to eutrophication water. This can be confirmed by adding calcium phosphate to the water brought into contact with the coal ash, whereby calcium phosphate is precipitated. However, when such a phosphorus adsorption mechanism is used, efficient phosphorus recovery is difficult.

On the other hand, FIG. 1 is a schematic diagram showing a mechanism of phosphorus adsorption to coal ash newly found by the present inventors. That is, coal ash, in particular there is a hollow particle 1 as shown in FIG. 1 in the fly ash, when immersed hollow particles 1 in a phosphate solution, phosphate ions PO ₄ ^2-hollow in the liquid The inventors have found a mechanism in which phosphorus is adsorbed inside the hollow particles 1 by passing through the gaps in the outer shell of the particles 1 and binding to calcium ions Ca ²⁺ inside the hollow particles 1.

  Such a phosphorus adsorption mechanism has been confirmed by the following procedure. First, when the coal ash (fly ash) was thoroughly washed and immersed in a phosphoric acid solution, the phosphoric acid concentration decreased. Then, when the surface of coal ash was confirmed with an electron microscope, the presence of phosphorus (phosphorus adsorption) was not observed on the surface. On the other hand, when particles having a relatively large particle diameter were separated from the coal ash by sieving and observed with an electron microscope, it was confirmed that many hollow particles were present. Thus, when hollow particles were ground and the internal element distribution was observed with an electron microscope or the like, the presence of calcium phosphate could be confirmed.

  Therefore, the purification and recovery method and the recovery device for phosphorus according to the present embodiment uses coal ash, particularly fly ash containing hollow particles, as an adsorbent for purifying and recovering phosphorus contained in eutrophication water. Basic. Here, fly ash is a kind of coal ash in which, for example, ash particles that are in a molten state by combustion in a coal-fired power plant and float in high-temperature combustion gas become spherical fine particles as the temperature decreases at the boiler outlet. It is mainly collected from silica, alumina, etc., and is collected by an electrostatic precipitator.

  FIG. 2 is a schematic diagram showing a system configuration example for realizing the phosphorus purification and recovery method of the present embodiment using the phosphorus adsorption mechanism. First, a purification and recovery device 10 for filling the coal ash 2 is prepared. The purification and recovery device 10 includes a housing 11 that is appropriately filled with a large number of coal ash 2. Here, the coal ash 2 includes at least the hollow particles 1. In the present embodiment, the coal ash 2 is used that has been sieved so that the particle size is relatively large and most of the hollow particles 1 are occupied. Such a purification and recovery device 10 is installed at an appropriate location outside the system of the closed purification target water area 12 having eutrophication water such as lakes and moats to be purified, and the eutrophication of the purification target water area 12 is performed. Water is pumped up by the pump 13 and poured into the purification and recovery device 10, water is passed through the coal ash 2 including the hollow particles 1 filled in the purification and recovery device 10, and the purified water is drained from the lower side. Reflux to the water area 12 to be purified.

  As described above, the eutrophication water of the purification target water area 12 is allowed to flow through the purification / recovery device 10, so that phosphorus contained in the eutrophication water is phosphate particles and the hollow particles 1 contained in the coal ash 2. Passes through the outer shell, and binds to calcium ions inside the hollow particles 1 and is recovered by adsorbing and fixing calcium phosphate inside. The eutrophication water is purified in a state where the phosphorus is purified. It will be refluxed to the water area 12.

  As described above, according to the method for purifying and recovering phosphorus according to the present embodiment, the purification target water area 12 is installed in the purification and recovery apparatus 10 that is installed outside the system to be purified 12 and is filled with the coal ash 2 including the hollow particles 1. The eutrophication water can be efficiently purified by allowing the eutrophication water to pass through and adsorbing and recovering phosphorus contained in the eutrophication water inside the hollow particles 1. And when the hollow particles 1 in the coal ash 2 reach the adsorption capacity, only the coal ash 2 containing the hollow particles 1 for the purification recovery device 10 installed outside the system 12 to be purified needs to be replaced, No soot treatment is required and no excess sludge is produced by soot, and a phosphorus purification and recovery method can be realized at low cost.

  Moreover, since the coal ash 2 including the used hollow particles 1 to be exchanged after reaching the adsorption capacity does not contain sludge or the like and has a high phosphorus recovery efficiency, the used coal ash 2 that has been taken out from the purification and recovery device 10 is used. This hollow particle 1 can be effectively reused as it is as an agricultural phosphorus fertilizer. That is, it is apparent that phosphorus is not adsorbed on the surface, and the hollow particles 1 that are subject to disposal can be effectively reused as they are according to the conventional mechanism of phosphorus adsorption of coal ash. is there.

  In this embodiment, the coal ash 2 in which the hollow particles 1 occupy the majority is sieved in advance, but the coal ash 2 containing at least the hollow particles 1 is used without sieving in advance. The coal ash 2 may be sieved during collection to separate the used hollow particles 1 and reused as phosphorus fertilizer.

It is a schematic diagram which shows the mechanism of the phosphorus adsorption | suction to the hollow particle utilized in this Embodiment. It is a schematic diagram which shows the system structural example for implement | achieving the purification and collection | recovery method of phosphorus of this Embodiment. It is a schematic diagram which shows the mechanism of the phosphorus adsorption | suction to the coal ash recognized conventionally.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Hollow particle 2 Coal ash 10 Purification | purification collection apparatus 11 Case 12 Water purifying object water area

Claims (3)

A purification and recovery device filled with coal ash containing hollow particles is installed outside the system to be purified,
Purifying and recovering phosphorus, wherein eutrophication water in the water area to be purified is passed through the purification and recovery device so that phosphorus contained in the eutrophication water is adsorbed inside the hollow particles. Method.   Phosphorus contained in the coal ash filled in the purification and recovery device installed outside the system of the purification target water area, receiving eutrophication water from the purification target water area, and phosphorus contained in the eutrophication water A method for reusing recovered phosphorus, characterized in that spent hollow particles adsorbed inside until reaching the adsorption capacity are used as an agricultural phosphorus fertilizer.   It is provided with a casing that is filled with coal ash containing hollow particles and installed outside the purification target water area, and the eutrophication water of the purification target water area is passed through the casing. Purification recovery device.

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