JP2014087787A - Processing method and processing device for manganese-containing water - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a processing method for manganese-containing water which supplies purified water having significantly low manganese concentration (approximately less than 0.001 mg/L).SOLUTION: A processing method for manganese-containing water comprises: an adjustment step in which chlorine is added to raw water containing soluble manganese so as to supply water to be treated; and a contact step in which the water to be treated is brought into contact with solid manganese dioxide so as to eliminate the soluble manganese contained in the water to be treated and supply purified water.

Description

  The present invention relates to a method and apparatus for treating manganese-containing water.

Article 4 of the Water Supply Law stipulates that the water quality standard value for manganese and its compounds is 0.05 mg / L. This is because manganese ions react slowly in the presence of chlorine and precipitate as black solids (hydrated manganese dioxide) in water pipes and the like.
Moreover, when this solid substance flows out to a faucet etc. by a water flow, it will become a problem as a coloring trouble (black water trouble) to tap water. Therefore, in recent years, some water utilities have voluntarily set stricter management reference values for manganese and its compounds, such as less than 0.001 mg / L.

  Generally, the removal apparatus of manganese and its compound used in a water purification plant is based on the manganese sand filtration method. In this method, it is necessary that manganese sand coated with manganese dioxide on the surface and free residual chlorine coexist. Manganese ions in the water are removed from the surface of the manganese sand in the form of manganese oxide having no manganese ion removal activity using the manganese dioxide as a catalyst. Manganese oxide generated on the surface of the manganese sand is oxidized to manganese dioxide by free residual chlorine and assimilated with the manganese sand, so that the manganese sand recovers its activity of removing manganese ions.

  As a specific conventional method related to such a technique, Patent Document 1 discloses a membrane module in which a large number of external pressure tubular membrane elements are incorporated in a membrane immersion tank, and an air diffuser is disposed below the membrane module. A hypoxia tank or a hypochlorite tank and a pulverized charcoal adsorption tank are installed in the previous stage of the membrane filtration device, and chlorine is added to the raw water followed by powdered activated carbon to oxidize soluble manganese in the raw water. It is made into manganese dioxide, and after suppressing the production of disinfection by-products due to the injection of chlorine, it is sent to a membrane filtration device to perform biological treatment and separation and removal of solid components, A method for treating manganese-containing water is described.

  Further, in Patent Document 2, when removing soluble manganese in raw water, an alkaline substance is supplied to the raw water to adjust the pH to 9 to 10, and the soluble manganese is dissolved in insoluble dioxide in the presence of dissolved oxygen. A method for removing manganese is described in which after manganese is formed, the produced manganese dioxide particles are removed from raw water by membrane filtration.

JP 2003-230895 A JP 2001-316118 A

  However, in the method described in Patent Document 1, it is necessary to inject sodium hypochlorite at a high concentration of 1.3 mg / L or more, which increases the amount of chemical used and is not economical. Further, since sodium hypochlorite is injected at a high concentration, the total trihalomethane, which is one of the water quality standard items, becomes high and there is a concern that the standard value may be exceeded, so adsorption with powdered activated carbon is necessary.

  Moreover, in the method of patent document 2, after inject | pouring an alkaline substance, after adjusting pH to 9-10, in order to comply with a tap water quality standard, sulfuric acid etc. are inject | poured and pH5.8-8. It is not economical because an operation to lower it to 6 is required.

  Moreover, the manganese density | concentration of the purified water obtained by processing by the conventional method as described in patent document 1 or patent document 2 is high, and there was room for further reduction.

An object of the present invention is to solve the above problems.
That is, an object of the present invention is to provide a method and an apparatus for treating manganese-containing water from which purified water having a very low manganese concentration (approximately less than 0.001 mg / L) can be obtained.

The present inventor has intensively studied to solve the above-described problems and completed the present invention.
The present invention includes the following (1) to (12).
(1) An adjustment step of adding chlorine to raw water containing soluble manganese to obtain water to be treated;
A contact step of contacting the water to be treated with solid manganese dioxide to remove soluble manganese contained in the water to be treated to obtain purified water; and
A method for treating manganese-containing water.
(2) An adjustment step [1] for adding chlorine to the raw water containing soluble manganese and further adjusting the pH to 6.5 to 8.5 to obtain the water to be treated [1];
Contacting the water to be treated [1] with solid manganese dioxide to obtain soluble water by removing soluble manganese contained in the water to be treated [1];
The method for treating manganese-containing water according to (1) above, comprising:
(3) Chlorine is added in the adjustment step [1] to adjust the pH so that the relationship between the pH of the purified water and the residual chlorine concentration (mg / L) in the contact step satisfies the following formula (I). The method for treating manganese-containing water according to (2) above.
Formula (I): 8.18-2.3 × residual chlorine concentration ≦ pH ≦ 8.46-1.2 × residual chlorine concentration (4) Chlorine is added to raw water containing soluble manganese, and hypochlorite ion An adjustment step [2] to obtain a water to be treated [2] by setting the concentration of (OCl ⁻ ) to 0.06 to 2.4 mg / L;
Contacting the water to be treated [2] with solid manganese dioxide to obtain soluble water by removing soluble manganese contained in the water to be treated [2];
The method for treating manganese-containing water according to (1) above, comprising:
(5) The adjustment step includes
A flocculating step of adding a flocculant to the raw water, flocculating and sedimenting impurities, and obtaining flocculated water as a supernatant;
An adsorption step of bringing the raw water or the flocculated water into contact with activated carbon to obtain purified water from which at least some of the impurities have been removed; and
The above (1) to (1) comprising at least one step selected from the group consisting of a filtration step of filtering the raw water, the agglomerated treated water or the purified water to obtain a filtered treated water from which at least a part of impurities has been removed. The method for treating manganese-containing water according to any one of 4).
(6) an adjustment unit that adds chlorine to the raw water and discharges water to be treated;
An apparatus for treating manganese-containing water, comprising: a contact portion that brings the treatment target water into contact with solid manganese dioxide, removes soluble manganese contained in the treatment target water, and discharges purified water.
(7) The manganese-containing water treatment apparatus according to (6), which is an adjustment unit that adds chlorine to the raw water, further adjusts the pH to 6.5 to 8.5, and discharges the water to be treated. .
(8) The adjustment unit has an alkali addition means for adding an alkaline component to the raw water used to adjust the pH of the raw water,
The manganese-containing water according to (6) or (7), wherein the contact portion further includes a cleaning unit that cleans the solid manganese dioxide using the water to be treated before the alkali component is added. Processing equipment.
(9) The adjustment unit is
A flocculant to add a flocculant to the raw water, agglomerate and settle impurities, and obtain agglomerated water as a supernatant;
An adsorbing part that obtains purified water from which at least a part of impurities has been removed by bringing the raw water or the agglomerated water into contact with activated carbon, and
The above (6) to (8) comprising at least one selected from the group consisting of a filtration unit for filtering the raw water, the agglomerated treated water or the purified water to obtain filtered treated water from which at least a part of impurities has been removed. ) The manganese-containing water treatment apparatus according to any one of the above.
(10) The treatment apparatus for manganese-containing water according to any one of (6) to (9), wherein the water to be treated is brought into contact with the solid manganese dioxide in a downward flow in the contact portion.
(11) The manganese-containing water treatment apparatus according to any one of (6) to (9), wherein the water to be treated is brought into contact with the solid manganese dioxide in an upward flow in the contact portion.
(12) The manganese-containing water treatment apparatus according to any one of (6) to (11), wherein the manganese-containing water treatment method according to any one of (1) to (5) can be performed.

  ADVANTAGE OF THE INVENTION According to this invention, the processing method and processing apparatus of the manganese containing water from which the manganese concentration is very low (generally less than 0.001 mg / L) can be provided.

It is a graph which shows the abundance ratio (mass ratio) of hypochlorous acid (HOCl) and hypochlorite ion (OCl < ^- >). It is an example of the apparatus which can perform the processing method of this invention. It is an example of the preferable apparatus which can perform the processing method of this invention. It is a graph showing the measurement result in an Example.

The present invention will be described.
The present invention adds chlorine to raw water containing soluble manganese to obtain a treatment target water, and contacts the treatment target water with solid manganese dioxide to remove the soluble manganese contained in the treatment target water And a contact process for obtaining purified water.
Hereinafter, such a method for treating manganese-containing water is also referred to as “treatment method of the present invention”.

The treatment method of the present invention includes two embodiments as preferred embodiments.
The first aspect of the treatment method of the present invention is the adjustment step [1] for adding chlorine to the raw water containing soluble manganese and further adjusting the pH to 6.5 to 8.5 to obtain the treatment target water [1]. A method of treating manganese-containing water, comprising: contacting the treatment target water [1] with solid manganese dioxide to remove soluble manganese contained in the treatment target water [1] to obtain purified water. It is.
Hereinafter, such a method for treating manganese-containing water is also referred to as “first treatment method of the present invention”.

In the second aspect of the treatment method of the present invention, chlorine is added to raw water containing soluble manganese, and the concentration of hypochlorite ion (OCl ⁻ ) is set to 0.06 to 2.4 mg / L. The adjustment step [2] for obtaining water [2] and the treatment target water [2] are brought into contact with solid manganese dioxide to remove the soluble manganese contained in the treatment target water [2] to obtain purified water. A method for treating manganese-containing water comprising a contact step.
Hereinafter, such a method for treating manganese-containing water is also referred to as a “second treatment method of the present invention”.

The first treatment method of the present invention and the second treatment method of the present invention have a common contact process.
The adjustment step [1] in the first processing method of the present invention and the adjustment step [2] in the second processing method of the present invention are partly in common.

In the following, the simple description “the processing method of the present invention” includes both the first processing method of the present invention and the second processing method of the present invention.
In addition, the simple description of “adjustment step” includes both the adjustment step [1] in the first treatment method of the present invention and the adjustment step [2] in the second treatment method of the present invention.

<Adjustment process>
The adjustment process in the processing method of the present invention will be described.
In the adjustment step, chlorine is first added to raw water containing soluble manganese.

The raw water is not particularly limited as long as it is water containing soluble manganese (that is, manganese ions). It may further contain undissolved solid manganese.
Examples of such raw water include tap raw water (river water, groundwater, lake water, etc.), sewage, seawater, brackish water, and the like.

  Although the density | concentration of the soluble manganese contained in raw | natural water is not specifically limited, About 0.005-0.06 mg / L may be sufficient.

  In the treatment method of the present invention, the concentration of soluble manganese is determined based on the provisions of a ministerial ordinance concerning water quality standards after filtering water to be measured (for example, raw water or purified water) with a membrane filter having a pore size of 0.1 μm. It means the value obtained by measuring by the method stipulated by the Minister of Health, Labor and Welfare (Ministry of Health, Labor and Welfare Notification No. 261 on July 22, 2003 (Final Revision March 30, 2012 Ministry of Health, Labor and Welfare Notification No. 290)) To do.

In the adjustment process, chlorine is added to such raw water.
Here, a substance containing chlorine (for example, a compound containing a chlorine atom) may be added to the raw water.
Examples of such a compound containing a chlorine atom include sodium hypochlorite, liquefied chlorine, and calcium hypochlorite. Especially, it is preferable to add chlorine to raw water by adding sodium hypochlorite. This is because it is widely distributed and easily available. Moreover, it is because injection | pouring is easy compared with another chlorine source.

  The amount of chlorine added to the raw water is not particularly limited, but the concentration of chlorine remaining in the purified water produced by carrying out the treatment method of the present invention (hereinafter also referred to as “residual chlorine concentration”) is preferably 2 mg / L. Below, more preferably 1.5 mgL or less, more preferably 1.0 mgL or less, and even more preferably 0.6 mgL or less of chlorine is added to the raw water.

  The residual chlorine concentration in clean water is determined by the inspection method for free and combined residual chlorine specified by the Minister of Health, Labor and Welfare based on the provisions of Article 17 Paragraph 2 of the Water Supply Law Enforcement Regulations (Ministry of Health, Labor and Welfare Notification No. 29 September 2003 It shall mean the value obtained by measuring 318 (final revision March 11, 2005 Ministry of Health, Labor and Welfare Notification No. 75)).

  In order to set the residual chlorine concentration in the purified water within the above range, the amount of chlorine added to the raw water can be set to an amount that provides a chlorine concentration of 2.0 mg / L or less in the raw water.

  In the adjustment step, chlorine is added to the raw water as described above. Chlorine can be added using a chlorine source addition device.

The case of the adjustment process [1] will be described.
In the adjustment step [1], the pH of the raw water as described above is set to 6.5 to 8.5. This pH is preferably 7.0 or more, and more preferably 7.5 or more. The pH is preferably 8.0 or less.

  After adding chlorine to the raw water or before adding chlorine, the pH is measured by, for example, a conventionally known method (for example, a method using a pH meter), and if necessary, an acid (sulfuric acid, hydrochloric acid, liquefied carbon dioxide) Etc.) and alkali (sodium hydroxide, slaked lime, soda ash, etc.) can be added to the raw water in an appropriate amount to adjust the pH. Even if no acid or alkali is added, as long as the pH is within a predetermined range, no acid or alkali may be added. Even such a case is within the technical scope of the processing method of the present invention.

  Here, in the adjustment step [1], chlorine is added to the raw water so that the relationship between the pH of purified water and the residual chlorine concentration (mg / L) in the contact step described later satisfies the following formula (I), and the pH is adjusted. It is preferable to adjust.

  Formula (I): 8.18-2.3 × residual chlorine concentration ≦ pH ≦ 8.46−1.2 × residual chlorine concentration

  The present inventor diligently studied and adjusted the pH by adding chlorine to the raw water in the adjustment step [1] so that the relationship between the pH in purified water and the residual chlorine concentration (mg / L) satisfies the formula (I). The manganese concentration in the purified water obtained by the first treatment method of the present invention was found to be very low, generally less than 0.001 mg / L.

  In the adjustment step [1], as described above, chlorine can be added to the raw water containing soluble manganese, and the water to be treated [1] can be obtained at a pH of 6.5 to 8.5.

The case of the adjustment process [2] will be described.
In the adjustment step [2], the concentration of hypochlorite ion (OCl ⁻ ) in the raw water as described above is set to 0.06 to 2.4 mg / L. The concentration of hypochlorite ion (OCl ⁻ ) is preferably 0.12 mg / L or more, and more preferably 0.36 mg / L or more. The concentration of this hypochlorite ion (OCl ⁻ ) is preferably 1.9 mg / L or less, more preferably 0.57 mg / L or less, and 0.48 mg / L or less. Further preferred.

  The present inventor has intensively studied, and when the concentration of hypochlorite ion is within a predetermined range, the manganese concentration in the purified water obtained by the second treatment method of the present invention becomes very low, generally less than 0.001 mg / L. I found out that

Although the reason why the manganese concentration in the purified water is so low that the concentration of hypochlorite ion in the treatment target water [2] is within the predetermined range is not clear, the present inventor estimates as follows.
In the contacting step, when the water to be treated [2] is brought into contact with solid manganese dioxide (hereinafter also referred to as “catalytic manganese dioxide”) as a catalyst, manganese ions contained in the water to be treated [2] It changes to manganese oxide on the surface and is further oxidized to manganese dioxide by residual chlorine.
Here, it is considered that residual chlorine that oxidizes manganese oxide to manganese dioxide is present in the form of hypochlorite ions (OCl ⁻ ) or hypochlorous acid (HOCl) in the target treated water [2]. It is presumed that manganese dioxide produced by oxidation by residual chlorine present in the form of hypochlorite ions (OCl ⁻ ) is adsorbed on the surface of the catalyst manganese dioxide and is easily assimilated with it. In contrast, manganese dioxide produced by oxidation with chlorine present in the form of hypochlorous acid (HOCl) is difficult to adsorb on the surface of the catalyst manganese dioxide and may not be adsorbed on the catalyst manganese dioxide. The present inventors presume that the manganese concentration in the purified water becomes higher by that amount because it exists as fine particles in the purified water.

In the adjustment step [2], the method for adjusting the concentration of hypochlorite ion (OCl ⁻ ) of the raw water as described above is not particularly limited, but by adjusting the chlorine and pH contained in the raw water, The concentration of chlorite ion (OCl ⁻ ) can be adjusted.
When chlorine or a compound containing chlorine is added to water, hypochlorous acid (HOCl) is generated, and hypochlorite ions (OCl ⁻ ) are generated, which is considered to be in a specific equilibrium state. And it is thought that the abundance ratio of hypochlorous acid (HOCl) and hypochlorite ion (OCl ⁻ ) depends on the pH of water. Specifically, the abundance ratio (mass ratio) of hypochlorous acid (HOCl) and hypochlorite ion (OCl ⁻ ) is approximately 90:10 when the pH is 6.5, and the pH is 7.0: 80:20, pH 7.5: 60:40, pH 8.0: 20:80, pH 8.5: 5: 95. Details of the abundance ratio (mass ratio) between hypochlorous acid (HOCl) and hypochlorite ions (OCl ⁻ ) are as shown in FIG.
Therefore, for example, when the concentration of chlorine contained in the raw water is high, the pH is lowered (for example, pH: about 6 to 7), and the concentration of hypochlorite ion (OCl ⁻ ) is adjusted to a predetermined range. Can do. Further, for example, when the concentration of chlorine contained in the raw water is low, the pH is increased (for example, pH: about 7.5 to 8.5), and the concentration of hypochlorite ion (OCl ⁻ ) is within a predetermined range. Can be adjusted.

In the adjustment step [2], the concentration of hypochlorite ion (OCl ⁻ ) in the raw water is specified by the following method.
First, the inspection method of free residual chlorine and combined residual chlorine specified by the Minister of Health, Labor and Welfare based on the provisions of Article 17 paragraph 2 of the Water Supply Law Enforcement Regulations (Ministry of Health, Labor and Welfare Notification No. 318 on September 29, 2003 (final revision Heisei The total concentration of hypochlorous acid (HOCl) and hypochlorite ion (OCl ⁻ ) in raw water, that is, free residual chlorine concentration, is measured according to the Ministry of Health, Labor and Welfare Notification No. 75) on March 11, 2005. Then, the concentration of hypochlorite ion (OCl ⁻ ) is determined from FIG.

In the adjustment step [2], as described above, chlorine is added to the raw water containing soluble manganese, and the concentration of hypochlorite ion (OCl ⁻ ) is set to 0.06 to 2.4 mg / L. 2] can be obtained.

The adjustment step preferably includes at least one step selected from the group consisting of an aggregation step, an adsorption step, and a filtration step.
When the said adjustment process includes the said adsorption process, it is preferable that the said filtration process is also included.
More preferably, the adjustment step includes all steps of the aggregation step, the adsorption step, and the filtration step.

More preferably, the adjustment step includes all steps of the aggregation step, the adsorption step, and the filtration step in this order.
That is, in the adjusting step [1], a flocculant is added to the raw water, and the impurities are aggregated and settled to obtain an agglomerated treated water as a supernatant. An adsorption step for obtaining purified water from which at least a part of the product has been removed, and a filtration step for obtaining filtered water from which the purified water has been removed by filtering the purified water, and adding chlorine to the filtered water Further, it is preferable to set the pH to 6.5 to 8.5 and obtain the treatment target water [1].
In addition, the adjustment step [2] is performed by adding a flocculant to the raw water, aggregating and precipitating impurities to obtain agglomerated treated water as a supernatant, contacting the agglomerated treated water with activated carbon, An adsorption step for obtaining purified water from which at least a part of the product has been removed, and a filtration step for obtaining filtered water from which the purified water has been removed by filtering the purified water, and adding chlorine to the filtered water Furthermore, it is preferable that the concentration of hypochlorite ion (OCl ⁻ ) is 0.06 to 2.4 mg / L to obtain the water to be treated [2].

For example, when the raw water is raw tap water (river water, lake water, groundwater, etc.), the adjustment step preferably includes at least one step selected from the group consisting of an aggregation step, an adsorption step, and a filtration step. It is more preferable that all the steps are included, and it is more preferable that all these steps are included in this order. When all processes are included, the adsorption process, the aggregation process, and the filtration process may be included in this order, or the aggregation process, the adsorption process, and the filtration process may be included in this order. This is because impurities contained in the raw water, mainly at least a part of the substance exhibiting ultraviolet absorbance, can be separated and removed from the raw water.
Here, the substance exhibiting UV absorbance means a substance that absorbs in the UV region (200 to 300 nm, preferably 220 to 280 nm, more preferably 250 to 260 nm). The organic substance having an unsaturated bond contained in the raw water is generally considered to be a substance exhibiting ultraviolet absorbance. Specific examples of the substance exhibiting UV absorbance include humic substances. The humic substance is a final decomposition product when a plant or the like is decomposed by a microorganism, and is a polymer compound composed of a linear hydrocarbon, a polycyclic aromatic compound, and the like.
A method for separating and removing such impurities from the raw water is not particularly limited. For example, a conventionally known method can be applied, but at least one step selected from the group consisting of a coagulation step, an adsorption step, and a filtration step. Is preferred.

  Each step of the aggregation step, the adsorption step, and the filtration step that can be included in the adjustment step will be described below.

<Aggregation process>
The coagulation step is a step of adding coagulant to the raw water to coagulate and settle the impurities to obtain coagulated treated water as a supernatant.

The flocculant is not particularly limited, and for example, a conventionally known one can be used. For example, Al-based and / or Fe-based flocculants can be used.
The Al-based flocculant contains an aluminum compound as a main component (content is 50% by mass or more, preferably 80% by mass or more, more preferably 95% by mass or more, and further preferably 100% by mass (substantially other In the following, the same applies to the flocculant.
Here, the aluminum compound means a compound containing Al atoms. Examples of the aluminum compound include polyaluminum chloride and sulfuric acid clay (aluminum sulfate).
The Fe-based flocculant means a flocculant mainly composed of an iron-based compound.
Here, the iron-based compound means a compound containing Fe atoms. Examples of iron-based compounds include ferric chloride and polyferric sulfate.

  The addition amount of the flocculant is preferably 0 to 150 mg / L, more preferably 25 to 120 mg / L as the addition amount with respect to 1 L of raw water.

  The flocculant may be in a powdery form, or in a form in which a powdery aluminum-based compound and / or iron-based compound is dispersed in a liquid.

  After adding the aggregating agent as described above, the impurities are aggregated by stirring as necessary, and at least a part of the generated aggregate is separated and removed to obtain agglomerated water as a supernatant. it can.

Chlorine is added to the agglomerated treated water, and the pH is set to 6.5 to 8.5, so that the treatment target water [1] to be used in the contact step can be obtained.
Chlorine is added to the agglomerated treated water, and the concentration of hypochlorite ion (OCl ⁻ ) is set to 0.06 to 2.4 mg / L to obtain treated water [2] for use in the contacting step.

<Adsorption process>
The adsorption step is a step of obtaining purified water from which at least a part of impurities has been removed by bringing the raw water or the flocculated water into contact with activated carbon. Here, activated carbon may be brought into contact with the raw water and the flocculated water.
Specifically, for example, powdered activated carbon is added to the raw water or the agglomerated water, and if necessary, the impurities are adsorbed on the activated carbon, and the purified carbon is obtained by separating and removing the activated carbon. Can do. In addition, for example, by flowing the raw water or the agglomerated water into a fixed bed filled with activated carbon, the raw water or the agglomerated water is brought into contact with the activated carbon to obtain purified water from which at least a part of impurities has been removed. it can.

  The addition amount of the activated carbon is preferably 0 to 100 mg / L, more preferably 0 to 25 mg / L as the addition amount with respect to 1 L of the raw water or the coagulated water.

Chlorine is added to the purified water, and the pH is set to 6.5 to 8.5, so that water to be treated [1] to be used in the contact step can be obtained.
Chlorine is added to the purified water, and the concentration of hypochlorite ion (OCl ⁻ ) is set to 0.06 to 2.4 mg / L to obtain water to be treated [2] to be used in the contacting step.

<Filtration process>
The filtration step is a step of obtaining filtered water from which at least a part of impurities has been removed by filtering the raw water, the agglomerated water or the purified water.
Here, two or more of the raw water, the flocculated water, and the purified water may be filtered.

  The method of the filtration treatment is not particularly limited, and for example, a conventionally known method can be applied. For example, a treatment using a filtration membrane can be applied. As a filtration membrane, a microfiltration membrane (MF), an ultrafiltration membrane (UF), a reverse osmosis membrane (RO), a nanofiltration membrane (NF), etc. can be used.

Chlorine is added to the filtered treated water, and the pH is set to 6.5 to 8.5, so that water to be treated [1] to be used in the contact step can be obtained.
Chlorine is added to the filtered water, and the concentration of hypochlorite ion (OCl ⁻ ) is set to 0.06 to 2.4 mg / L, so that water to be treated [2] to be used in the contacting step can be obtained.

<Contact process>
Next, a contact process is demonstrated.
The contact process in the 1st processing method of this invention and the contact process in the 2nd processing method of this invention are the same.
That is, in the treatment method of the present invention, the contact step is the treatment target water (treatment target water [1] in the first treatment method of the present invention, and treatment target water [2] in the second treatment method of the present invention. The same applies hereinafter) is brought into contact with solid manganese dioxide to remove the soluble manganese contained in the water to be treated to obtain purified water.

In the contacting step, the water to be treated is brought into contact with solid manganese dioxide (catalyst manganese dioxide).
The catalyst manganese dioxide is not particularly limited as long as at least a part of the solid surface is made of manganese dioxide. For example, a film of manganese dioxide may be formed on the surface of a string-like or net-like solid matrix. It is preferable to use conventionally known manganese sand as the catalyst manganese dioxide.

Here, the manganese sand preferably has an effective diameter of 0.45 to 0.7 mm, more preferably about 0.6 mm.
The manganese sand preferably has a specific surface area of ² to 25 m ² / g, and more preferably ^{2 to} 3 m ² / g.

The water to be treated is brought into contact with such catalyst manganese dioxide.
For example, the water to be treated can be brought into contact with catalytic manganese dioxide by supplying the water to be treated to a contact tank filled with manganese sand and allowing the water to pass through.

The treatment target water may be passed through the contact tank by either an upward flow or a downward flow, but the treatment target water is preferably passed through the contact tank by a downward flow. This is because the manganese concentration contained in the obtained purified water tends to be lower.
When passing the water to be treated in a downward flow to the contact tank, the water flow rate is preferably 360 to 2200 m / day, and more preferably 2000 m / day or less.
When passing the water to be treated in an upward flow to the contact tank, the water flow rate is preferably 300 m / day or more.

By such a treatment method of the present invention, purified water having a very low manganese concentration (generally less than 0.001 mg / L) can be obtained.
The manganese concentration in the purified water is determined by the Minister of Health, Labor and Welfare based on the provisions of the Ministerial Ordinance on Water Quality Standards (Ministry of Health, Labor and Welfare Notification No. 261 issued on July 22, 2003 (final revision March 30, 2012 Notification of the Ministry of Health, Labor and Welfare) 290))).

<Apparatus of the present invention>
Next, a manganese-containing water treatment apparatus that can carry out the treatment method of the present invention will be described.
The treatment method of the present invention removes soluble manganese contained in the water to be treated by adding chlorine to the raw water and discharging the water to be treated, and bringing the water to be treated into contact with solid manganese dioxide. And it can implement by the processing apparatus of manganese containing water which has a contact part which discharges purified water.
Hereinafter, such a processing apparatus is also referred to as “the apparatus of the present invention”.

  In the apparatus of the present invention, the adjustment unit is preferably an adjustment unit that adds chlorine to the raw water, further adjusts the pH to 6.5 to 8.5, and discharges the water to be treated.

In the apparatus of the present invention, it is preferable that the adjustment unit includes at least one selected from the group consisting of the aggregation unit, the adsorption unit, and the filtration unit.
Here, the agglomeration part is a part in which an aggregating agent is added to the raw water, and impurities are aggregated and settled to obtain agglomerated treated water as a supernatant. Chlorine can be added to the agglomerated treated water (preferably, the pH is further adjusted) to discharge the water to be treated to be provided to the contact portion.
The adsorbing part is a part for obtaining purified water from which at least a part of impurities has been removed by bringing the raw water or the flocculated water into contact with activated carbon. Chlorine can be added to the purified water (preferably, the pH is further adjusted) to discharge the water to be treated to be provided to the contact portion.
The filtration unit is a part that obtains filtered treated water from which at least a part of impurities has been removed by filtering the raw water, the agglomerated treated water or the purified water. Chlorine can be added to the filtered water (preferably, the pH is further adjusted) to discharge the water to be treated to be provided to the contact portion.

The apparatus of the present invention preferably includes the filtering unit when the adjusting unit includes the adsorption unit.
In the apparatus of the present invention, it is more preferable that the adjustment unit includes all of the aggregation unit, the adsorption unit, and the filtration unit.

In the apparatus of the present invention, it is more preferable that the adjustment unit includes all of the aggregation unit, the adsorption unit, and the filtration unit in this order.
That is, the apparatus of the present invention adds a flocculant to the raw water, agglomerates and precipitates impurities, and agglomerates to obtain agglomerated treated water as a supernatant. An adsorption part for obtaining purified water from which at least a part has been removed, and a filtration part for filtering the purified water to obtain filtered water from which at least some of the impurities have been removed, and adding chlorine to the filtered water ( Preferably, the pH is further adjusted), the adjustment unit for discharging the water to be treated, and the water to be treated are brought into contact with solid manganese dioxide to remove soluble manganese contained in the water to be treated, thereby purifying the water. It is more preferable that it is a manganese-containing water treatment device having a contact portion for discharging water.
Hereinafter, such a device is also referred to as a “preferred device of the present invention”.
A preferred apparatus of the present invention will be described below with reference to FIG.

The preferred apparatus of the present invention (hereinafter also referred to as “apparatus 10”) shown in FIG. 2 has, in order from the upstream side, a raw water tank 12, a coagulation treatment apparatus 14, a membrane filtration apparatus 16, and a contact oxidation tank 18, and further activated carbon. It is an apparatus having an adding device 22 and an alkali and chlorine source adding device 24.
The aggregation processing device 14 corresponds to the aggregation part, and the aggregation process in the processing method of the present invention can be performed.
The activated carbon addition device 22 corresponds to the adsorption part, and can perform the adsorption step in the treatment method of the present invention.
The membrane filtration device 16 corresponds to a filtration part, and can perform the filtration step in the treatment method of the present invention.
Aggregation treatment device 14, activated carbon addition device 22, membrane filtration device 16, and alkali and chlorine source addition device 24 correspond to the adjustment unit, and the adjustment step in the treatment method of the present invention can be performed.
The contact oxidation tank 18 corresponds to a contact portion, and the contact step in the treatment method of the present invention can be performed.

  Each part of the apparatus 10 will be described.

  The raw water tank 12 may be any tank that can store raw water, and may be, for example, a tank. When the processing method of the present invention is performed using the apparatus 10, the raw water 3 is first stored in the raw water tank 12.

The coagulation treatment apparatus 14 is not particularly limited as long as it has an aspect capable of adding a coagulant to the raw water 3 and separating and removing impurities.
For example, what is provided with a coagulation sedimentation tank and a coagulant addition means is illustrated. In such a case, the raw water 3 is received from the raw water tank 12 into the coagulation sedimentation tank, and a desired amount of the coagulant is added thereto by the coagulant adding means, stirred as necessary, and the coagulated treated water as the supernatant is discharged. .

  The activated carbon addition device 22 has a structure capable of adding a desired amount of powdered activated carbon to the agglomerated treated water. When powdered activated carbon is added, impurities contained in the flocculated water are adsorbed, and purified water from which impurities are removed can be obtained.

The membrane filtration device 16 includes, for example, an MF membrane having a nominal pore diameter of 0.05 μm.
The membrane filtration device 16 has a structure capable of filtering the purified water and discharging the filtered water.

  The alkali and chlorine source adding device 24 has a structure capable of adding an alkali (for example, sodium hydroxide) and a chlorine source (for example, sodium hypochlorite) to the filtered water. This allows a desired amount of chlorine source to be added to the filtered water. In addition, a desired amount of alkali can be added as necessary to adjust the pH.

The contact oxidation tank 18 is provided with a filling tank filled with manganese sand, and has a structure capable of passing the filtered water in a downward flow and discharging the purified water 5 from which manganese has been removed. ing.
In the apparatus of the present invention, the filtered water may be passed in an upward flow in the contact oxidation tank.

When the raw water is tap raw water (river water, lake water, groundwater, etc.), the treatment method of the present invention is preferably treated using the preferred apparatus of the present invention in the form shown in FIG.
In the case where the raw water is clear water such as well water and water quality items other than manganese satisfy the tap water quality standard, the agglomeration treatment device 14, membrane filtration device 16 and activated carbon in the device 10 shown in FIG. It is preferable that the addition apparatus 22 is not provided (that is, an apparatus having the raw water tank 12 and the contact oxidation tank 18 and further having an alkali and chlorine source addition apparatus 24 in order from the upstream side).

2 is an embodiment in which activated carbon is added from the activated carbon adding device 22 to the aggregating treated water discharged from the aggregating treatment device 14, but in the apparatus of the present invention, for example, the aggregating treatment device 14 is used. Activated carbon may be added from the activated carbon addition device 22 to the raw water 3 flowing into the water. Further, instead of the activated carbon addition device 22, for example, an agglomeration treatment water or raw water may be flowed into a fixed bed filled with activated carbon for treatment.
2 is a mode in which alkali and chlorine sources can be added to the filtered water discharged from the membrane filtration device 16, but in the device of the present invention, for example, it flows into the membrane filtration device 16. An alkali and chlorine source may be added to the purified water. The alkali and chlorine sources are preferably added after the activated carbon is added from the activated carbon addition device 22.
In addition, in the apparatus 10 shown in FIG. 2, the alkali and chlorine source addition apparatus 24 is shown as one apparatus. However, in the apparatus of the present invention, the apparatus for adding alkali and the chlorine source are independent of each other. And a device for adding the.

It is preferable that the contact portion (contact oxidation tank 18) further has a cleaning means for cleaning the solid manganese dioxide using the water to be treated before adding the alkali component.
Specifically, it is preferable that the apparatus of the present invention is a water purification system having an aspect as shown in FIG.

  The apparatus 10 ′ shown in FIG. 3 is a flow path for supplying, to the apparatus 10 shown in FIG. 32. The pre-treatment water is supplied to the contact oxidation tank 18 through the flow path 32, and the solid manganese dioxide provided in the contact oxidation tank 18 can be washed. Specifically, for example, water to be treated can be supplied from a reverse direction to a filling tank filled with manganese sand to wash (backwash) the manganese sand.

  In the water purification system capable of performing the treatment method of the present invention, the concentration of turbid components in pre-treatment water (in the embodiment of FIG. 3, the filtered treatment water before adding an alkali component) is very low (generally 0.05). Less than). Therefore, this pre-treatment water can be used to wash the solid manganese dioxide provided in the contact oxidation tank 18. In this case, a tank for storing water for cleaning the contact oxidation tank is unnecessary, which is preferable.

  The apparatus 10 ′ shown in FIG. 3 has a flow path 32 for supplying water to be treated (water before treatment) to the contact oxidation tank 18 before adding the alkali component and the water to be treated after addition of the alkali component to the contact oxidation tank Switching valves 36 and 38 are installed in each of the flow paths 34 to be supplied to 18. By simply switching these valves, the water to be treated after the addition of the alkali component can be supplied to the contact oxidation tank 18 or the pre-treatment water can be supplied to the contact oxidation tank 18 and backwashed.

  Using such apparatus 10 and apparatus 10 ', the processing method of the present invention can be preferably implemented.

Raw water was continuously treated using the water purification system shown in FIG.
The water purification system shown in FIG. 2 used in the examples will be described more specifically.

The raw water tank 12 is a cylindrical tank having a capacity of 500 L capable of storing raw water.
The aggregating apparatus 14 includes an aggregating tank and an aggregating agent adding means. The coagulation treatment apparatus 14 has a structure that can receive the raw water 3 from the raw water tank 12 into the coagulation tank, add a desired amount of the coagulant to the coagulation tank, stir as necessary, and discharge the coagulation treatment water. .
The activated carbon addition device 22 has a structure capable of adding a desired amount of powdered activated carbon to the agglomerated treated water.
The membrane filtration device 16 is provided with an MF membrane having a nominal pore size of 0.05 μm, and has a structure capable of filtering the agglomerated treated water (purified water) to which powdered activated carbon is added if necessary and discharging the filtered treated water. It has.
The alkali and chlorine source adding device 24 has a structure capable of adding a desired amount of sodium hydroxide and sodium hypochlorite to the filtered water.
The contact oxidation tank 18 is provided with a filling tank filled with manganese sand. Filtered water to which sodium hypochlorite is added and sodium hydroxide is further added as required is passed in a downward flow. It has a structure that can be drained with purified water 5 from which soluble manganese has been removed. Manganese sand having a pore diameter of about 0.6 mm was used. The specific surface area of manganese sand is 2.2 m ² / g.

  Raw water 3 is river water of Shin-Kushiro River, manganese concentration is about 0.016-0.12 mg / L, pH is about 6.5-7.2, and turbidity is river water of 2-80 degrees. is there.

For such raw water 3, a target value of ultraviolet absorbance was previously determined, and the relationship between the ultraviolet absorbance removal rate and the flocculant injection rate was determined. Further, the relationship between the impurity concentration (turbidity component concentration) and the correction value of the flocculant injection rate was determined.
Here, the ultraviolet absorbance removal rate is calculated from the following equation.
UV absorbance removal rate (%) = (UV absorbance of raw water−target value of UV absorbance) / UV absorbance of raw water × 100

Raw water was continuously treated using such a water purification system (apparatus 10).
First, the raw water 3 was stored in the raw water tank 12, the raw water 3 was periodically sampled in the raw water tank 12, the ultraviolet absorbance and the impurity concentration were measured, and the amount of the flocculant to be added was determined.

Next, the raw water 3 was received in the coagulation treatment apparatus 14, and the amount of the coagulant obtained above was added and stirred. In addition, a pH adjuster (sulfuric acid) was added to adjust the pH to 6.0 to 6.3 to improve the aggregation efficiency.
PAC was used as the flocculant. The amount of flocculant added was in the range of 50-100 mg / L.

  Next, the agglomerated water discharged from the agglomeration processing apparatus 14 was sampled, and the ultraviolet absorbance was measured. And compared with the predetermined target ultraviolet-ray light absorbency, when this was not able to be achieved, the powdered activated carbon was added to the aggregating process water from the activated carbon addition apparatus 22. FIG. As in the case of the amount of flocculant added in the raw water 3 described above, the relationship between the UV absorbance removal rate and the amount of powdered activated carbon to be added is obtained in advance, and based on this, the powdered activated carbon is added to the flocculent treated water. Added. The amount of powdered activated carbon added was in the range of 0 to 10 mg / L.

  Next, using the membrane filtration device 16, the agglomerated treated water (purified water) after adding powdered activated carbon as necessary was filtered to obtain filtered treated water.

Next, using the alkali and chlorine source addition device 24, the desired amounts of sodium hydroxide and sodium hypochlorite are added to the filtered water to make the pH 6.5 to 8.5 and hypochlorite ions, respectively. After the concentration of (OCl ⁻ ) was set to 0.06 to 2.4 mg / L, purified water 5 was obtained by treatment using the contact oxidation tank 18.
Here, sodium hydroxide and sodium hypochlorite were added so that the relationship between the pH in the purified water 5 and the residual chlorine content satisfied the above-described formula (I). Sodium hydroxide was added in the range of 3-8 mg / L, and sodium hypochlorite was added in the range of 0.7-1.2 mg / L.
The water flow rate in the contact oxidation tank 18 was 360 to 2200 m / day.

  Next, the pH of the purified water 5, the residual chlorine concentration (mg / L), and the manganese concentration (mg / L) were measured. The measurement results are shown in Table 1.

Moreover, FIG. 4 shows the relationship between the pH and the residual chlorine concentration (mg / L) when the manganese concentration in the purified water 5 is less than 0.001 mg / L.
From FIG. 4, it can be said that when the formula (I) is satisfied, the manganese concentration is less than 0.001 mg / L.

DESCRIPTION OF SYMBOLS 3 Raw water 5 Purified water 10 Apparatus 12 Raw water tank 14 Aggregation processing apparatus 16 Membrane filtration apparatus 18 Contact oxidation tank 22 Activated carbon addition tank 24 Alkali and chlorine source addition apparatus

Claims (12)

An adjustment step of adding chlorine to raw water containing soluble manganese to obtain water to be treated;
A contact step of contacting the water to be treated with solid manganese dioxide to remove soluble manganese contained in the water to be treated to obtain purified water; and
A method for treating manganese-containing water. An adjustment step [1] for adding chlorine to the raw water containing soluble manganese, further adjusting the pH to 6.5 to 8.5, and obtaining the water to be treated [1];
Contacting the water to be treated [1] with solid manganese dioxide to obtain soluble water by removing soluble manganese contained in the water to be treated [1];
The processing method of the manganese containing water of Claim 1 provided with these. The pH is adjusted by adding chlorine in the adjustment step [1] so that the relationship between the pH of the purified water and the residual chlorine concentration (mg / L) in the contacting step satisfies the following formula (I). The method for treating manganese-containing water as described in 1. above.
Formula (I): 8.18-2.3 × residual chlorine concentration ≦ pH ≦ 8.46−1.2 × residual chlorine concentration Chlorine is added to the raw water containing soluble manganese, and the concentration of hypochlorite ion (OCl ⁻ ) is set to 0.06 to 2.4 mg / L, and the adjustment step [2] to obtain the water to be treated [2];
Contacting the water to be treated [2] with solid manganese dioxide to obtain soluble water by removing soluble manganese contained in the water to be treated [2];
The processing method of the manganese containing water of Claim 1 provided with these. The adjusting step is
A flocculating step of adding a flocculant to the raw water, flocculating and sedimenting impurities, and obtaining flocculated water as a supernatant;
An adsorption step of bringing the raw water or the flocculated water into contact with activated carbon to obtain purified water from which at least some of the impurities have been removed; and
5. The method according to claim 1, comprising at least one step selected from the group consisting of a filtration step of filtering the raw water, the agglomerated treated water or the purified water to obtain a filtered treated water from which at least a part of impurities has been removed. The method for treating manganese-containing water according to any one of the above. An adjustment unit for adding chlorine to the raw water and discharging the water to be treated;
An apparatus for treating manganese-containing water, comprising: a contact portion that brings the treatment target water into contact with solid manganese dioxide, removes soluble manganese contained in the treatment target water, and discharges purified water.   The treatment apparatus for manganese-containing water according to claim 6, which is an adjustment unit that adds chlorine to the raw water, further adjusts the pH to 6.5 to 8.5, and discharges the water to be treated. The adjusting unit has an alkali addition means for adding an alkaline component to the raw water used to adjust the pH of the raw water;
8. The apparatus for treating manganese-containing water according to claim 6, wherein the contact portion further includes a cleaning unit that cleans the solid manganese dioxide using water to be treated before adding the alkali component. The adjustment unit is
A flocculant to add a flocculant to the raw water, agglomerate and settle impurities, and obtain agglomerated water as a supernatant;
An adsorbing part that obtains purified water from which at least a part of impurities has been removed by bringing the raw water or the agglomerated water into contact with activated carbon, and
Any one of Claims 6-8 including at least 1 chosen from the group which consists of the filtration part which filters the said raw | natural water, the said coagulation | flourization process water, or the said purified water, and obtains the filter process water which removed at least one part of the impurity. An apparatus for treating manganese-containing water according to claim 1.   The treatment apparatus for manganese-containing water according to any one of claims 6 to 9, wherein, in the contact portion, the water to be treated is brought into contact with the solid manganese dioxide in a downward flow.   The treatment apparatus for manganese-containing water according to any one of claims 6 to 9, wherein in the contact portion, the water to be treated is brought into contact with the solid manganese dioxide in an upward flow.   The processing apparatus of manganese containing water in any one of Claims 6-11 which can perform the processing method of manganese containing water in any one of Claims 1-5.