JP2005087943A - Method for removing soluble manganese - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for removing soluble manganese by using a compact apparatus, capable of easily adjusting the operation of the apparatus even when the volume of raw water fluctuates. <P>SOLUTION: This method comprises: the first process of adding sodium-hypochlorite 14 and manganese sand 18 which is a catalyst particle to raw water 12 containing the soluble manganese in a mixing tank 10 and mixing the same; the second process of feeding treated water 22 treated in the first process to a membrane module 26 in which the treated water is separated into treated water 28 and a membrane separation substance 30 by membrane filtration; and the third process of recovering the manganese sand 18 from the membrane separation substance 30 to return the recovered manganese sand 18 to the first process for reuse. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for removing soluble manganese, and more particularly, to a method for removing soluble manganese by removing manganese from raw water containing soluble manganese to obtain treated water suitable for beverages and the like.

  Raw water such as river water and groundwater usually contains a small amount of soluble manganese. In order to treat this raw water to obtain treated water (clean water) suitable for beverages and the like, it is necessary to remove soluble manganese so that the dissolved manganese is below the reference value. As a method for removing soluble manganese, a contact manganese sand filtration method has been known for a long time.

  This contact manganese sand filtration method is a method in which an oxidizing agent such as sodium hypochlorite is added to raw water containing soluble manganese, and water is passed through a filtration tower filled with manganese sand. Soluble manganese is rapidly oxidized by the catalytic action of manganese dioxide supported on the surface of manganese sand. While raw water passes down the manganese sand filter layer, the soluble manganese becomes manganese dioxide having a new catalytic ability and is oxidized and trapped on the surface of the manganese sand. Other turbid components in the raw water are also filtered out by the manganese sand filter layer. However, this contact manganese sand filtration method tends to clog the filter layer. For this reason, it is necessary to make the water flow rate of a filtration tower low, and processing efficiency is bad. When the raw water contains a large amount of turbidity, clogging of the filter layer is accelerated, so that frequent backwashing operation of the filter layer is required, and the processing efficiency is further reduced.

  In order to improve the drawbacks of the conventional contact manganese sand filtration method, Patent Document 1 and Patent Document 2 describe a method in which raw water is passed upward through a reaction tank filled with catalyst particles such as manganese sand. Is disclosed. When raw water comes into contact with fluidized catalyst particles, oxidation of soluble manganese is promoted. Manganese oxide fine particles deposited by oxidation are discharged from the reaction tank accompanying the upward flow of the raw water, and are separated and removed from the treated water by the membrane separation means provided in the subsequent stage. According to this method, the flow rate of the upward flow can be increased to improve the processing efficiency. Further, there is no problem of clogging of the filter layer as in the contact manganese sand filtration method, and there is an advantage that the back washing operation of the filter layer is not required.

JP-A-7-39872 JP 2003-103275 A

  As described above, the methods disclosed in Patent Document 1 and Patent Document 2 are effective and efficient, but require a reaction tank filled with catalyst particles, which increases the installation area of the apparatus, There was a problem that the configuration was complicated. In addition, there is a problem that it is difficult to adjust the upward flow rate of the raw water in the reaction tank. For example, when the amount of raw water is small, the upward flow rate becomes small, and the formation of a fluidized bed of catalyst particles in the reaction tank becomes insufficient. Further, when the amount of raw water is large, the upward flow velocity is increased, and some of the catalyst particles are easily accompanied by the upward flow and overflow from the reaction tank. Therefore, even when the amount of raw water fluctuates, it is necessary to devise a driving operation for properly maintaining the upward flow velocity.

  The object of the present invention is to improve the above-mentioned problems of the prior art, improve the processing efficiency, reduce the size of the apparatus configuration, and easily dissolve even when the amount of raw water varies. It is to provide a method for removing manganese.

In order to achieve the above object, a method for removing soluble manganese according to the present invention includes a first step of adding catalyst particles and an oxidant to raw water containing soluble manganese and mixing, and a target that has undergone the first step. A second step of separating the treated water into a treated water and a membrane separation by membrane filtration, collecting the catalyst particles from the membrane separation separated in the second step, and collecting the collected catalyst particles into the first step And a third step of returning.
It is preferable to use a liquid cyclone as a means for recovering the catalyst particles in the third step. It is preferable to use a ceramic membrane or a polyvinylidene fluoride membrane as a membrane material for the membrane filtration in the second step.

  According to the present invention, the catalyst particles added to the raw water in the first step are subjected to membrane separation together with other fine turbid components in the second step. The catalyst particles separated in the second step were collected in the third step, returned to the first step, and reused. For this reason, a filtration tower and an upflow type reaction tank as in the prior art are not required. Therefore, it is possible to realize a method for removing soluble manganese that has high processing efficiency, can be made compact in apparatus configuration, and can be easily handled in operation even when the amount of raw water varies.

  FIG. 1 is a flow sheet showing a first embodiment of a method for removing soluble manganese according to the present invention. Raw water 12 containing soluble manganese flows into the mixing tank 10, and sodium hypochlorite 14 is added as an oxidant according to the amount of raw water 12 flowing in.

  Further, manganese sand 18 separated by a liquid cyclone 16 described later is added to the mixing tank 10. Manganese sand 18 is catalyst particles in which manganese dioxide is supported on the surface of sand, and particles having a particle diameter of about 1 mm are used. The mixing tank 10 includes a stirrer 20. In this mixing tank 10, raw water 12, added sodium hypochlorite 14 and manganese sand 18 are mixed by a stirrer 20.

  Then, the soluble manganese in the raw water is rapidly oxidized by the oxidizing power of sodium hypochlorite 14 and the catalytic action of manganese dioxide on the surface of manganese sand 18 to become a fine manganese oxide insoluble matter. The treated water 22 in the mixing tank 10 is pumped by the pump 24 to the subsequent membrane module 26 in a state where the generated manganese oxide insoluble matter, manganese sand, and other turbid components originally contained in the raw water are mixed. .

  In the membrane module 26, the treated water 22 that has flowed in is subjected to membrane filtration to be separated into treated water 28 and a membrane separation 30. Note that sodium hypochlorite remains in the water to be treated 22 and there is a possibility that the membrane material of the membrane module 26 is oxidized and deteriorated. Accordingly, an inorganic ceramic membrane is preferable as the membrane material used for the membrane module 26. As the organic film material, a polyvinylidene fluoride film having oxidation resistance is preferably used.

  As described above, soluble manganese in raw water is oxidized to become manganese oxide insoluble matter, and this manganese oxide insoluble matter is separated as a part of the membrane separation 30 by the membrane module 26. Therefore, the soluble manganese in the treated water 28 can be reduced to a reference value or less suitable for beverages, for example. The treated water 28 is once stored in the treated water storage tank 32 and then put to practical use.

  On the other hand, the membrane separation 30 separated by the membrane module 26 is a muddy material in which manganese sand, manganese oxide insoluble matter and other turbid components are mixed. The membrane separation 30 is once stored in the separation tank 34 and then pumped to the hydrocyclone 16 by a pump 36. In the hydrocyclone 16, manganese sand having a large particle size is separated and recovered from the bottom of the hydrocyclone 16. This separated and collected manganese sand 18 is returned to the mixing tank 10 and reused. From the inner cylinder 38 of the hydrocyclone 16, fine manganese oxide insoluble matter and other turbid components are discharged as discharged sludge 40. In some cases, a part of the manganese sand is mixed in the discharged sludge 40 and discharged out of the system. In such a case, the amount of manganese sand 18 that is circulated and used in the system gradually decreases, leading to a reduction in processing efficiency. Therefore, new manganese sand 42 is replenished as necessary.

As described above, according to the method of the present embodiment, the manganese sand 18 added to the raw water in the mixing tank 10 in the first step is separated together with other fine turbid components by the membrane module 26 in the second step. The manganese sand 18 separated in the second step was recovered by the liquid cyclone 16 in the third step, returned to the mixing tank 10 in the first step, and reused.
For this reason, it is possible to realize a method for removing soluble manganese that has high processing efficiency, can be made compact in apparatus configuration, and can be easily handled in operation even when the amount of raw water varies. Further, when a cross-flow type membrane module is employed as the membrane module 26, manganese sand having a relatively large particle size always collides with the membrane surface of the membrane module and exerts an action of cleaning the membrane surface. For this reason, there is an effect that the frequency of the periodic cleaning operation of the membrane module can be reduced.

  FIG. 2 is a flow sheet showing a second embodiment of the method for removing soluble manganese according to the present invention. The raw water 50 containing soluble manganese is once stored in the raw water tank 52 and then pumped to the membrane module 56 by the pump 54. Sodium hypochlorite 58 and manganese sand 60 are added in the process of pumping the raw water 50, and the raw water 50, sodium hypochlorite 58, and manganese sand 60 are mixed by a line mixer 62 provided in the pumping line 61. Is done. Then, the soluble manganese in the raw water is rapidly oxidized by the oxidizing power of the sodium hypochlorite 58 and the catalytic action of the manganese sand 60 to become fine manganese oxide insoluble matter. This treated water 64 reaches the subsequent membrane module 56 in a state in which the produced manganese oxide insoluble matter, manganese sand, and other turbid components originally contained in the raw water are mixed. In the membrane module 56, the treated water 64 that has flowed in is subjected to membrane filtration to be separated into treated water 66 and membrane separation 68. The treated water 66 is once stored in the treated water storage tank 70 and then put to practical use.

  On the other hand, after the membrane separation 68 separated by the membrane module 56 is once stored in the separation tank 72, a part thereof is circulated to the membrane module 56 by the pump 74, and the remainder is pumped to the separator 76. As the separator 76, a centrifugal separator or a screen type separator can be used in addition to the liquid cyclone, and manganese sand having a large particle size is separated and recovered. The separated and collected manganese sand 60 is returned to the pumping line 61 and reused. The fine manganese oxide insoluble matter and other turbid components, which are the other separated product in the separator 76, are discharged as discharged sludge 78. In addition, when a part of the manganese sand is mixed in the discharged sludge 78 and the amount of the manganese sand 60 to be circulated in the system is gradually reduced, a new manganese sand 80 is replenished as necessary.

  According to the second embodiment, since the line mixer 62 is used as a means for adding and mixing sodium hypochlorite 58 and manganese sand 60 to the raw water 50, the apparatus configuration is further improved compared to the first embodiment. Compactness can be achieved. A part of the separated product 68 stored in the separated product tank 72 is circulated to the membrane module 56. For this reason, when the membrane module 56 is a cross-flow type membrane module, it is easy to adjust the liquid flow rate.

  In each said embodiment, sodium hypochlorite was illustrated as an oxidizing agent added to raw | natural water. However, the oxidizing agent according to the present invention is not limited to sodium hypochlorite, and other oxidizing agents such as potassium permanganate may be used. The catalyst particles are not limited to manganese sand, and other catalyst particles that promote oxidation of soluble manganese may be used.

1 is a flow sheet showing a first embodiment of a method for removing soluble manganese according to the present invention. It is a flow sheet which shows a 2nd embodiment of a removal method of soluble manganese concerning the present invention.

Explanation of symbols

10 ......... Mixing tank, 12,50 ......... Raw water, 14,58 ......... Sodium hypochlorite, 16 ......... Liquid cyclone, 18,60 ......... Manganese sand, 22,64 ......... Coated Treated water, 26, 56 ......... Membrane module, 28, 66 ......... Treatment water, 30, 68 ......... Separate, 34, 72 ......... Separate tank, 40, 78 ......... Sludge discharged, 76 ………Separator.

Claims (3)

  A first step in which catalyst particles and an oxidizing agent are added to and mixed with raw water containing soluble manganese, and a second step in which the water to be treated after the first step is subjected to membrane filtration to separate it into treated water and a membrane separation. And a third step of recovering the catalyst particles from the membrane separation separated in the second step and returning the recovered catalyst particles to the first step.   The method for removing soluble manganese according to claim 1, wherein a liquid cyclone is used as means for collecting the catalyst particles in the third step. The method for removing soluble manganese according to claim 1 or 2, wherein a ceramic membrane or a polyvinylidene fluoride membrane is used as a membrane material for membrane filtration in the second step.

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