JPH1085762A - Apparatus for removing phosphorus in river water - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable dephosphorization treatment simply without sludge generation by supplying river water by adding calcium ion into a reactor in which a dephosphorization material mainly containing calcium silicate hydrate is packed or fluidized or into river water. SOLUTION: River water containing phosphorus, after being subjected to decarboxylation treatment by a decaroxylation reactor 11, is sent to a calcium ion mixing tank 12, in which calcium salt such as calcium chloride is added. Calcium salt can be added into a crystallization reactor 13. Next, water is sent to the reactor 13 and added with sodium hydroxide, etc., from a pH adjusting means 14 to adjust pH. The reactor 13 makes a dephosphorization material mainly containing calcium silicate hydrate be packed or fluidized and conducts the dephosphorization reaction of supplied river water. Tobermorite, etc., are used as calcium silicate hydrate. The basic system 10, when the concentration of organic substances or suspended substances is extremely low, can be used alone and is returned to the river after dephosphorization treatment.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a phosphorus removal apparatus for removing phosphorus from river water containing phosphorus, and more particularly, to a reaction tank filled or fluidized with a phosphorus removal material mainly composed of calcium silicate hydrate. The present invention relates to a device for removing phosphorus contained in river water.

[0002]

2. Description of the Related Art Sources of phosphorus contained in river water include municipal sewage treated water that is not subjected to advanced treatment, miscellaneous wastewater, industrial wastewater from factories, livestock waste, agricultural lands, and wastewater from mountain forests. There is. When the final destination of rivers is closed sea areas, lakes and marshes, it is necessary to remove phosphorus as a causative substance in order to prevent eutrophication of these water areas. Also,
When river water is used for hydrophilic and scenic use, it is necessary to remove phosphorus, the causative substance, in order to suppress the deterioration of the landscape and the generation of odor due to the occurrence of adherent algae and planktonic algae.

[0003] As a river purification method for improving the quality of river water, there are few techniques for easily removing phosphorus.
A so-called contact aeration method such as a gravel contact method is applied. This is for organic matter and suspended matter,
Phosphorus removal has not generally been performed. Coagulation sedimentation is only known as a slightly selectable technique.

[0004]

However, the disadvantages of this method are that sludge increases in proportion to the amount of flocculant added, that the flocculant added is wasted, and that flocculent particles (flock) are not used. There is a drawback that the method for removing phosphorus from river water is not simple, such as the necessity of a sedimentation tank for sedimentation separation.

[0005]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an apparatus capable of dephosphorizing a river water without generating sludge with a simpler apparatus configuration than the conventional method. Another object of the present invention is to provide a phosphorus removing device capable of removing phosphorus from a large amount of river water for a long period of time.

[0006]

According to the first aspect of the present invention, there is provided a reaction tank filled or flowed with a dephosphorizing material mainly composed of calcium silicate hydrate, and supplied to or supplied to the reaction tank. An addition means for adding calcium ions to river water containing phosphorus to be removed.

According to a second aspect of the present invention, there is provided the apparatus for removing phosphorus in river water according to the first aspect, further comprising a decarboxylation means for performing a decarboxylation treatment on the river water.

According to a third aspect of the present invention, there is provided the apparatus for removing phosphorus in river water according to the first or second aspect, further comprising a pH adjusting means for adjusting a pH value of the river water staying in the reaction tank. is there.

[0009]

According to the first to third aspects of the present invention, phosphorus is removed from the river water by flowing the river water containing phosphorus into the reaction tank. This reaction tank is filled with a dephosphorizing material mainly composed of calcium silicate hydrate or is fluidized. Then, calcium ions are supplied to the river water or the reaction tank. This supply of calcium ions is performed, for example, by supplying calcium chloride to river water. Further, the river water is subjected to decarbonation treatment and then flows and stays in the reaction tank. Further, the pH value of the river water staying in the reaction tank is adjusted to, for example, 8 to 10. As a result, dephosphorization from river water can be performed for a long time without generating sludge.

Here, the reason why the addition of calcium ions in a reaction tank filled or fluidized with a dephosphorizing material mainly composed of calcium silicate hydrate is necessary for phosphorus removal will be described. In a batch processing experiment using a batch processing device consisting of this reaction tank and circulation pump, various concentrations of orthophosphate phosphorus were set from low to high, and the concentration that changes over time was analyzed kineticly. did. That is, the zero-order reaction rate constant is determined between the measurement points, the value is plotted against the average phosphorus concentration in each section, and the gradient is determined as the first-order reaction rate constant. As a result, it became clear that the reaction rate increased in proportion to the phosphorus concentration. Therefore, it can be understood that the phosphorus removal reaction by this reaction tank can be approximated by a primary reaction in terms of phosphorus concentration from a low concentration to a high concentration, and that the applicable phosphorus concentration range is wide.

Next, the concentration of phosphorus in raw water obtained by adding phosphorus to tap water as simulated water of river water is 50 mg / liter, 10%.
A continuous treatment experiment was performed with three types of 0 mg / liter and 200 mg / liter, and the actual residence time of raw water in the reaction tank was 1 hour. The zero-order reaction rate constant was determined from the phosphorus concentration that changes over time, and the value was plotted against the phosphorus concentration at that time to examine the change in the reaction rate. As a result, the reaction rate decreases as the number of treatment days elapses, and finally converges to a constant reaction rate. From the relationship between the phosphorus concentration and the reaction rate at each elapsed day, a proportional relationship is recognized in the low concentration range. Therefore, a primary reaction regarding the phosphorus concentration was observed. In the high concentration region, the reaction rate is constant regardless of the phosphorus concentration. This is a zero-order reaction with respect to phosphorus concentration. In all regions of the phosphorus concentration, the rate decreased according to the number of days elapsed, so that the existence of a reaction-limiting factor other than the phosphorus concentration became clear. Since this dephosphorization method utilizes the crystallization phenomenon of hydroxyapatite, its molecular formula:
Comprehensively judging Ca ₁₀ (OH) ₂ (PO ₄ ) ₆ and the above experimental results, it can be inferred that the reaction rate-limiting factor is calcium ion concentration. Then, the decrease in the concentration of calcium ions eluted from the dephosphorizing material filled in the reaction tank over the number of days resulted in a decrease in the reaction rate. It is recognized that calcium ions need to be added in order to stably operate the phosphorus removal system using a phosphorus removal material mainly composed of calcium silicate hydrate for a long period of time.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the apparatus for removing phosphorus from river water according to the present invention will be described below. FIG. 1 is a block diagram showing a phosphorus removing device according to one embodiment. As shown in this figure, the phosphorus removing device has the following configuration as the basic system 10. That is, a river water containing phosphorus is supplied, and a decarboxylation reaction tank 11 for performing a decarboxylation treatment on the river water, a calcium ion mixing tank 12 disposed downstream of the decarbonation reaction tank 11, The basic system 10 includes a crystallization reaction tank 13 disposed downstream of the calcium ion mixing tank 12 and pH adjusting means 14 for adjusting the pH of the crystallization reaction tank 13. .
When calcium ions are directly added to the crystallization reaction tank 13, the calcium ion mixing tank 12 can be omitted in the above system.

The decarboxylation reaction tank 11 contains a chemical (sulfuric acid)
Is injected into river water in the required amount. Therefore, for example, a sulfuric acid injection pump, a blower, and the like are attached to the decarboxylation reaction tank 11 as necessary. In the calcium ion mixing tank 12, a calcium salt such as calcium chloride is added and supplied to the decarbonated river water. In the crystallization reaction tank 13, a reaction tank filled or fluidized with a dephosphorizing material mainly composed of calcium silicate hydrate is used. As the calcium silicate hydrate, tobermorite, zonotlite, hillebrandite,
It is one or a combination of two or more of minute plate-like crystals, columnar crystals and needle-like crystals of wollastonite.

Further, the pH adjusting means 14 includes:
For example, there is injection of a pH adjusting agent (such as sodium hydroxide). Therefore, the pH adjusting means 14 can be configured by attaching a chemical injection pump or the like to the crystallization reaction tank 13.

The basic system 10 according to the above configuration can be used alone when the concentration of organic matter and suspended matter in river water is extremely low. For example, the river water is directly led to the decarboxylation reaction tank 11 of the basic system 10, and further,
This river water is returned to the river via the calcium ion mixing tank 12 and the crystallization reaction tank 13.

In addition, the basic system 10 can be used by being interposed downstream of the river purification system 20 shown in FIG. In FIG. 2, the basic system 10 is provided immediately downstream of the contact aeration facility. By interposing this position, the phosphorus concentration in the treated water can be reduced. The river water from the river is used for contact aeration 20
(Conventional river purification system) and is led from the contact aeration facility 20 to the basic system 10. The treated water thus purified and dephosphorized is returned to the river.

FIG. 3 shows an example in which a hydrophilic / scenery facility 30 is further provided downstream of the basic system 10. By supplying the purified and dephosphorized river water to the hydrophilic / landscape facility 30, the hydrophilic / landscape facility 30 can be made more effective. This is because the dephosphorized river water suppresses the generation of algae, thereby preventing the landscape from deteriorating due to the adhesion of algae and eliminating the generation of off-flavors caused by the algae.
Note that the hydrophilic / scenery facilities are, for example, murmuring, fountains, wall springs, and the like.

FIG. 4 shows an example of the contact aeration method facility 20. The river water is processed by passing through a sand settling tank 21, an inflow pump tank 22, a contact aeration tank 23, and a final settling tank 24 in this order. The treated water of the contact aeration method is supplied to the decarboxylation reaction tank 11 of the basic system 10.

As an example of the apparatus for removing phosphorus in river water, the example using the above-mentioned basic system 10 has been shown in the above-mentioned embodiment. Of phosphorus can also be removed.

[0020]

According to the present invention, river water can be dephosphorized for a long period of time without generating sludge.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an apparatus for removing phosphorus from river water according to one embodiment of the present invention.

FIG. 2 is a block diagram showing a state in which the apparatus for removing phosphorus in river water according to one embodiment of the present invention is incorporated in a part of a river purification system using a contact aeration method.

FIG. 3 is a block diagram showing a state in which a device for removing phosphorus in river water according to one embodiment of the present invention is incorporated in a part of a river purification system using a contact aeration method, and a hydrophilic / scenery facility is additionally provided. .

FIG. 4 is a schematic diagram showing an example in which a basic system according to an embodiment of the present invention is incorporated in a conventional medium-scale river purification system.

[Explanation of symbols]

 10 basic system, 11 decarboxylation reaction tank, 12 calcium ion mixing tank, 13 crystallization reaction tank, 14 pH adjustment means.

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Yuji Tsukamoto 1-1, Donan-cho, Yawata-nishi-ku, Kitakyushu-shi, Fukuoka Prefecture Cement Development Center, Mitsubishi Materials Corporation

Claims (3)

[Claims] 1. A method of adding a calcium ion to a reaction tank filled or fluidized with a dephosphorizing material mainly composed of calcium silicate hydrate, and a phosphorus-containing river water supplied to or supplied to the reaction tank. An apparatus for removing phosphorus from river water, comprising: an adding unit. 2. The apparatus for removing phosphorus from river water according to claim 1, further comprising a decarbonation means for performing a decarboxylation treatment on the river water. 3. The method according to claim 1, further comprising a pH adjusting means for adjusting a pH value of the river water staying in the reaction tank.
3. The apparatus for removing phosphorus from river water according to claim 1.