JP3593631B2 - Iron / manganese removal method and removal device - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention removes iron and manganese in the water to be treated such as groundwater and underground water, and converts the water to be treated to industrial water (miscellaneous water, industrial water, snow water, construction water, etc.) or tap water (drinking water, etc.). The present invention relates to a method and an apparatus for removing iron and manganese, which can be used for water.
[0002]
[Prior art]
Methods for removing iron and manganese in water to be treated such as groundwater and underground water include a method of performing coagulation and sedimentation while adding an oxidizing material and a method of using microorganisms such as iron bacteria that require a relatively long treatment time. However, the most frequently used autocatalysts, in which iron oxide and manganese oxide are attached to the surface of a filter medium while adding an oxidizing agent to maintain an oxidizing atmosphere, And a contact filtration method in which treatment is performed.
The contact filtration method utilizes the property that iron and manganese in the water to be treated adhere to the surface of the solid at the beginning of oxidation, and if the manganese oxide itself is in an oxidizing atmosphere, it becomes catalytic. It is based on the principle of oxidizing iron and manganese that have flowed in by promoting oxidation and attaching them to the surface of the filter medium to remove them continuously.
[0003]
FIG. 9 is a partially transparent side view of a filtration tank used in a conventional removal device for removing iron and manganese from water to be treated. The filtration tank has a sprinkling nozzle 15 for supplying the water to be treated into the upper part, and a water collecting strainer 16 for collecting the filtered treated water at the lower part. The filter layer 14 and the support gravel layers 17 and 18 composed of the attached filter medium particles are arranged. Such a conventional filtering device requires a gravel layer, and it is difficult to reduce the size because the gravel layer is present.
[0004]
[Problems to be solved by the invention]
If the filtration is continuously continued, a limit point at which the filtration cannot be performed eventually appears. This is because the iron content is physical filtration, which causes clogging of the filter medium filtration layer. As for manganese, the manganese oxide attached to the surface of the filter medium continues to attach manganese and enlarges, and eventually becomes unable to be adsorbed.
When back washing is performed here, iron oxide, which is an obstacle to physical filtration, is discharged by a flow opposite to the filtration, and clogging is eliminated. On the other hand, the manganese oxide that has become enlarged by adsorbing manganese also has its epidermis peeled off and discharged, but at that time, the original manganese oxide attached to the filter material may also be peeled off and discharged, As a result, the amount of manganese oxide decreases, which affects manganese removal.
Manganese can complete the natural complete oxidation under an atmosphere of PH 10 or more, so an environment of PH 10 or more is required for activation and regeneration.
In addition, water used for industrial water or the like removes iron and manganese by such a method. Conventional removal devices (filtration devices) include a filtration tower for removing iron and a filtration tower for removing manganese. There were two towers, which resulted in an increase in the size of the removal device.
[0005]
The present invention has been made in view of such circumstances, and removes iron, manganese, and the like from treated water, such as groundwater and underground water, by a filtering means having a novel structure, and further performs sterilization processing to remove the treated water. Water and industrial water (miscellaneous water, industrial water, snow removal water, construction water, etc.) and tap water (drinking water, etc.) are used to remove iron and manganese and used to carry out this method. A removal device is provided.
[0006]
[Means for Solving the Problems]
The present invention relates to a method for removing iron and manganese and the like from the water to be treated such as groundwater and underground water, and further performing a sterilization treatment, and a removing apparatus for performing the method. And it is characterized in that iron and manganese are removed in this filtration tank. The filtration tank accommodates a water collecting strainer and a filtration layer disposed thereon, and the filtration layer is formed by sintering clay several times and having fine porous particles as a base material and manganese oxidation. The filter material particles have a particle diameter of 0.28 to 0.65 mm and a mesh width of the water collecting strainer of 0.15 to 0.25 mm. And
There are different requirements for filter media between iron-removing media and manganese-removing media (for example, iron removal is a physical filtration, so the linear velocity (filtration speed) is slowed down. It is necessary to slow down the contact area and the filtration rate), so that both requirements could be satisfied by sufficiently examining the filter medium and limiting the particle size of the filter medium particles. Further, by using a water collecting strainer having a limited mesh width below the filtration layer in the filtration tank, the conventionally required filter material supporting gravel is not required, and the tank itself can be reduced in size.
[0007]
Further, in the present invention, a sterilizing agent is used as an oxidizing agent without using a coagulant for removing iron, so that a coagulating device is not required. This is because the cluster of ferric hydroxide generated by sodium hypochlorite used as a sterilant is small and has passed with the conventional filter media diameter, but it is sufficient to make the particle size as above small Filtration becomes possible.
The filter layer used in the present invention is composed of filter medium particles obtained by sintering clay several times and having dense porosity as a base, and manganese oxide attached to the base. For example, a chamotte base material having dense porosity obtained by firing clay several times is used. The chamotte base material has excellent adhesion to manganese oxide, and has a specific gravity of about 1.0 in apparent specific gravity, and is suitable for rapid filtration.
Such a matrix is alternately reacted with manganese chloride (MnCl ₂ .4H ₂ O) and potassium permanganate (KMnO ₄ ) in a rotary reactor, and this is repeated several times, followed by baking. When a certain amount of manganese chloride and potassium permanganate are reacted, sticky brown to dark brown manganese higher oxides (MnO.Mn ₂ O ₇ , MnO ₂ .H ₂ O) are produced ((1), (See equation (2)). This oxide is attached to a base and sintered to obtain filter medium particles.
Na ₂ Z + MnCl ₂ → MnZ + 2NaCl (1)
MnZ + 2KMnO ₄ → K ₂ Z · MnO · Mn ₂ O ₇ (2)
[0008]
The removing device used in the method for removing iron and manganese of the present invention performs not only filtration but also processes such as back washing, filtration washing, and circulation washing. Backwashing removes accumulated iron by physical filtration. In the filtration washing, an oxidizing agent is added to activate and regenerate the manganese oxide used in the filtration layer. Further, activation and regeneration of the manganese oxide is performed by setting the pH of the treated water to 10 or more by circulation cleaning.
In the filtration washing, in the related art, there are a method of washing with water to be treated and a method of washing with treated water that has been subjected to a filtration treatment. The former cannot be expected to be effective because it is washed with the water to be treated. The latter requires equipment for storing treated water.
In the present invention, since the size of the system is reduced, the amount of water required for filtration and cleaning can be reduced, and as a result, a cleaning water tank for storing treated water for use as cleaning water in the system can be installed as necessary. Can be.
In addition, the catalytic function of manganese oxide used as a filter material deteriorates. In order to activate and regenerate the catalytic function, the presence of activating water near PH10 is required. For this reason, in the present invention, an oxidizing agent, for example, activated water mixed with sodium hypochlorite and adjusted to around PH10 is used in the treated water used as the washing water, and the activated water is closed and circulated to reduce the manganese oxide. Activate and regenerate.
[0009]
Next, the mechanism for removing iron and manganese in the filtration treatment of the present invention will be described.
1. To remove iron in water for iron removal, iron is converted into an insoluble oxide, which is filtered through a filter (filter layer).
Iron is dissolved in alkaline water in the form of iron bicarbonate. And it is stable in the presence of an appropriate amount of CO ₂ (see equation (3)).
Fe (HCO ₃ ) ₂ ← → FeCO ₃ + CO ₂ + H ₂ O (3)
When CO ₂ decreases and the equilibrium is broken, the reaction proceeds to the reaction on the right side of the equation (3) to generate iron carbonate and further hydrolyze to generate colorless ferrous hydroxide (Fe (OH) ₂ ) (( 4) See formula).
FeCO ₃ + H ₂ O → Fe (OH) ₂ + CO ₂ ↑ (4)
Ferrous hydroxide is easily oxidized with the mixing of oxygen and the passage of time, and changes into a hardly soluble, red-rust-colored ferric hydroxide (Fe (OH) ₃ ) having a solubility of 0.01 ppm or less ((5) ) Expression).
2Fe (OH) ₂ + _{1 /} 2O ₂ + H ₂ O → 2Fe (OH) ₃ (5)
[0010]
The iron content in the water is changed to ferric hydroxide by the oxidation reaction of sodium hypochlorite (see formula (6)).
2Fe ²⁺ + NaClO + 5H ₂ O → 2Fe (OH) ₃ + NaCl + 4H ⁺ (6)
Since the ferric hydroxide oxidized by sodium hypochlorite is insoluble, it is filtered while passing through the filter medium (see equation (7)).
Fe (HCO ₃ ) ₂ + NaClO + H ₂ O → 2Fe (OH) ₃ ↓ + NaCl (7)
Further, the oxidized γ-iron oxyhydroxide is adsorbed on the filter medium and removed from the iron (see equation (8)).
Z-MnO · Mn ₂ O ₇ + 4Fe (HCO ₃ ) ₂ → Z- [Mn ₂ O] ^3- [γ-FeOOH] ⁴ + 8CO ₂ + 2H ₂ O (8)
2. About manganese removal [0011]
Oxidation reaction between manganese in water and sodium hypochlorite (see equation (9)) produces black-brown manganese dioxide hydrate.
The dissolved ratio of manganese is much smaller than that of iron, but it is not easily oxidized by air like iron, and is easily oxidized by sodium hypochlorite. This is because iron naturally oxidizes at a pH of 7 or more, whereas manganese does not spontaneously complete oxidation at a pH of 10 or more.
Mn ²⁺ + NaClO + 2H ₂ O → MnO ₂ .H ₂ O + NaCl + 2H ⁺ (9)
Sodium hypochlorite, which is an oxidizing agent, is continuously injected to oxidize manganese in contact with the surface of the filter material and adsorbed and removed by the filter material (see equation (10)). Z indicates a mother.
Z- [MnO (OH) ₂ ] + Mn (HCO ₃ ) ₂ + NaOCl → Z- [MnO (OH) ₂ ] ² + 2CO ₂ + NaCl (10)
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to FIGS.
1 is a schematic system diagram of an iron / manganese removing device, FIG. 2 is a flowchart illustrating a flow of removing iron / manganese using the removing device of FIG. 1, and FIG. 3 is a removing device of FIG. FIG. 4 is a schematic system diagram illustrating a flow of filtration using the removing device of FIG. 1, FIG. 4 is a schematic system diagram illustrating a flow of back washing using the removing device of FIG. 1, and FIG. FIG. 6 is a schematic system diagram illustrating the flow of circulation cleaning using the removal device of FIG. 1, FIG. 7 is a schematic diagram of the removal device shown in FIG. 1, and FIG. FIG. 2 is a partial perspective side view of a filtration tank used in the removal device of FIG. 1. As shown in FIGS. 1 and 7, the iron / manganese removing device 10 includes a filtration tower 1, a five-way switching valve 2, a regulating valve 3, an oxidizing device 4 having an oxidation pump, a backwash water tank 5, and a control tank. It has a board 6. Well water is treated as the treated water 8 and connected to the removing device 10 by piping. The pipe I led out of the well is connected to a removing device 10 via pipes A and G via a three-way switching valve 9. A filtration / backwash pump 7 is disposed in the pipe A, and is configured to supply the water 8 to be removed into the removing device 10. The pipe G is connected to the backwash water tank 5.
[0013]
The filtration tank 1 is connected to a pipe B that supplies the water 8 to be treated from above, and is connected to a pipe C that supplies treated water obtained by filtering the water 8 to be treated. The pipe A, the pipe B, the pipe C, the pipe D, and the pipe H are connected to the five-way switching valve 2. The oxidizing agent is supplied from the oxidizing device 4 to the pipe A via the oxidizing valve. The backwash water tank 5 has a capacity of, for example, 250 liters, and is configured to be connected to a pipe E to be supplied with treated water, and to be connected to a pipe G to supply treated water stored in the tank to a pipe A. It is configured to be supplied. The pipe E is connected to a pipe D and a pipe F via a branch valve, and the pipe F is configured to supply treated water to the outside. The control panel 6 adjusts the filtration, back washing, filtration washing, and circulation washing performed inside the removing device so that they are properly processed.
FIG. 8 is a partially transparent side view for explaining the inside of the filtration tank 1. The filtration tank has a sprinkling nozzle 12 for supplying the water to be treated into the upper part, and a collecting strainer 13 for collecting the filtered treated water at the lower part. In the meantime, the clay is sintered several times. The filter layer 11 is formed of fine particles having fine porosity as a matrix, and filter material particles in which manganese oxide is attached to the matrix. The particle size of the filter medium particles is 0.28 to 0.65 mm. The mesh width of the water collecting strainer is 0.15 to 0.25 mm. The cross-sectional area of the filtration tank of this embodiment is, for example, 0.126 m ² , and its processing capacity is, for example, 2.5 m ³ / hour.
[0014]
Next, the flow of filtering the water to be treated, which is controlled by the control panel, into treated water will be described with reference to FIGS. Although FIG. 2 is a diagram showing a system flow for automatically controlling the operation of the removing device, it is a flowchart for explaining a filtration-backwashing-filtration washing process, and does not include circulation washing. When a filtration treatment is performed by this removing apparatus, back washing and filtration washing must be performed as post-treatments, but circulation washing is not a treatment that must be performed. Since the process is appropriately performed when the filtration state of the apparatus deteriorates, it is not included in the flow shown in FIG.
First, the three-way switching valve 9 is switched to the direction of the filtration treatment, and the water 8 to be treated from a well or the like is supplied to the pipe A through the pipe I, and is supplied to the inside of the removing device 10 by the filtration / backwash pump 7. Then, an oxidizing agent such as sodium hypochlorite is supplied from the oxidizer 4 to the water to be treated through the oxidizer valve while passing through the pipe A. The water to be treated in the pipe A is supplied to the filtration tank 1 through the pipe B via the five-way switching valve 2, and the filtration process starts. At this time, if the pressure in the apparatus is high, the water supply pump (filtration / backwash pump 7) is stopped, and the operation standby state is maintained until the pressure reaches a predetermined pressure. When the pressure reaches a predetermined value, the operation of the water supply pump and the oxidation pump in the oxidation device is started. When the predetermined time has elapsed, the filtration process ends, and the process proceeds to the backwashing process.
[0015]
As shown in FIG. 8, the water to be treated supplied from the pipe B flows from the sprinkling nozzle 12 to the filtration layer 11, is filtered, and is supplied as treated water to the outside via the water collecting strainer 13. The supplied treated water derived from the lower portion of the filtration tank 1 passes through a pipe C, a five-way switching valve 2, a pipe D, a branch valve, and a pipe E connecting the branch valve to the backwash water tank 5 and a treated water outlet. It is supplied to the connecting pipe F. In this manner, the water to be treated is filtered and supplied to the outside from the treated water outlet as treated water. In this treated water, iron and manganese are removed by filtration (for example, iron can be reduced to 0.3 ppm or less and manganese can be reduced to 0.05 ppm or less). The filtration speed of the removing device of this embodiment is, for example, 20 m / hour.
[0016]
Next, the flow of the reverse cleaning process will be described with reference to FIGS.
The back washing is performed after the filtration treatment, and is intended to remove the accumulated iron content from the filtration layer by physical filtration. First, the three-way switching valve 9 is operated to supply the treated water in the backwash water tank 5 from the pipe G to the pipe A. At this time, no oxidizing agent is mixed in the treated water of the pipe A. The treated water in the pipe A is caused to flow to the five-way switching valve 2 by the operation of the filtration / backwashing pump 7, to flow through the pipe C by operating the five-way switching valve 2, supplied to the filtration tank 1, and backwashed. Operation is started. That is, the backwash is performed for a predetermined time by flowing from the lower part of the filtration tank through the water collecting strainer and the filtration layer to the pipe B from the upper part. The treated water flowing into the pipe B is discharged to the outside from the drain through the pipe H by switching the five-way switching valve 2.
In the present invention, since only one filtration tank is used, the size of the system is reduced, and as a result, the amount of water required for backwashing can be reduced.
[0017]
Next, the flow of the filtration cleaning process will be described with reference to FIGS.
The filtration washing is performed after the back washing treatment, and is intended to activate and regenerate the manganese oxide used in the filtration layer by adding an oxidizing agent. First, the three-way switching valve 9 is operated to flow the water to be treated 8 from the well or the like to the pipe A, and the filtration / backwash pump 7 is operated to send out the water to be treated in the pipe A. At this time, the oxidizing valve is opened and the oxidizing agent is mixed into the water to be treated in the pipe A by the oxidizing pump from the oxidizing device 6. The water to be treated in the pipe A is flowed into the pipe B by operating the five-way switching valve 2 and is supplied to the filtration tank 1 to start the filtration and washing processing. That is, the filter washing is performed for a predetermined time by flowing from the upper part of the filtration tank through the filtration layer and the water collecting strainer to the pipe C from the lower part. The treated water flowing into the pipe C is discharged to the outside from the drain through the pipe H by switching the five-way switching valve 2. The filtering and washing speed of the removing apparatus of this embodiment is, for example, 20 m / hour.
[0018]
Next, the flow of the circulation cleaning process will be described with reference to FIG.
Circulation washing is performed, for example, after filtration and washing, filtration is performed after treated water is stored in a backwash water tank, and the purpose is to activate and regenerate manganese oxide by setting the pH of treated water to 10 or more. . First, the three-way switching valve 9 is operated to supply the treated water in the backwash water tank 5 from the pipe G to the pipe A. At this time, the oxidizing valve is opened and the oxidizing agent is mixed into the treated water of the pipe A from the oxidizing device 6 by the oxidizing pump. The treated water in the pipe A is caused to flow to the five-way switching valve 2 by the operation of the filtration / backwashing pump 7, and then to the pipe B by operating the five-way switching valve 2, supplied to the filtration tank 1 and circulated. Operation is started. That is, the treated water in the pipe C is supplied to the backwash water tank 4 by operating the five-way switching valve 2 by flowing the water from the upper part of the filtration tank through the filtration layer and the water collecting strainer to the pipe C. In this way, the circulation cleaning is performed for a predetermined time.
[0019]
The catalytic function of manganese oxide used as a filter material deteriorates. In order to activate and regenerate the catalyst function, the presence of treated water having a pH of 10 or more is required. Therefore, as described above, the activated water adjusted to PH 10 or more by mixing an oxidizing agent such as sodium hypochlorite into the treated water used as the washing water, and closing and circulating the activated water to activate and regenerate the manganese oxide. Do.
[0020]
【The invention's effect】
By removing iron and manganese from treated water, such as groundwater and underground water, using a single filtration tank, the size of the equipment can be reduced, so that groundwater can be used in homes and small businesses that could not be installed conventionally. It became possible to do.
[Brief description of the drawings]
FIG. 1 is a schematic system diagram of an apparatus for removing iron and manganese according to the present invention.
FIG. 2 is a flowchart illustrating a flow of removing iron and manganese using the removal device of FIG. 1;
FIG. 3 is a schematic system diagram illustrating a flow of filtration using the removal device of FIG. 1;
FIG. 4 is a schematic system diagram illustrating a flow of back washing using the removal apparatus of FIG. 1;
FIG. 5 is a schematic system diagram illustrating a flow of filtration and washing using the removal device of FIG. 1;
FIG. 6 is a schematic system diagram illustrating a flow of circulating cleaning using the removal apparatus of FIG. 1;
FIG. 7 is a schematic diagram of the removing device of FIG. 1;
FIG. 8 is a partially transparent side view of a filtration tank according to the present invention used in the removing device of FIG. 1;
FIG. 9 is a partially transparent side view of a filtration tank used in a conventional removal device.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Filtration tank, 2 ... Five-way switching valve, 3 ... Regulating valve, 4 ... Oxidizing apparatus, 5 ... Backwash water tank, 6 ... Control panel, 10 ... Iron -Manganese removal device, 11, 14 ... filtration layer, 12, 15 ... watering nozzle, 13, 16 ... water collecting strainer, 17, 18 ... support gravel layer.

Claims (2)

A step of adding an oxidizing agent to the water to be treated, and a filter layer composed of filter medium particles obtained by sintering the clay several times and having dense porous particles as a matrix, and manganese oxide attached to the matrix. During the process of removing the iron and manganese contained in the water to be treated by passing the water through the filtration tank containing the collecting strainer and the process of taking out the treated water from the normally used outlet, Having a means for branching and storing in a backwash water tank as backwash water, a step of backwashing the inside of the filtration tank with the treated water from the backwash water tank, and after the backwash, an oxidizing agent is added to the water to be treated. Supplying and filtering and washing to activate and regenerate the manganese oxide, the filter medium particle diameter is 0.28 to 0.65 mm, and the mesh width of the water collecting strainer is 0.15 to 0.15 mm. ０．２0.25 mm, and The oxidizer for adding an oxidizing agent to the water to be treated is performed, the filtering tank and the backwash water tank is housed in the apparatus for removing a single iron-manganese, treated water stored in the backwash water tank Supplying an activation water adjusted to PH 10 or more by adding an oxidizing agent to the filtration tank, and activating and regenerating the manganese oxide by closing and circulating the activation water. the method of removing the iron-manganese. An oxidizing device that supplies an oxidizing agent to be added to the water to be treated, a filtration tank, and a fine porosity particle, which is housed in the filtration tank and is obtained by sintering clay several times, is used as a base material, and manganese oxide is produced. A filtration layer composed of filter material particles attached to the base, a water collection strainer that is stored in the filtration tank and collects treated water that has passed through the filtration layer, and a treatment water extracted from the filtration tank are branched. Means for storing backwash water in a backwash water tank, the filter medium particle diameter is 0.28 to 0.65 mm, the mesh width of the water collecting strainer is 0.15 to 0.25 mm, The inside of the filtration tank is backwashed with the treated water from the backwash water tank, and after the backwash, an oxidizing agent is supplied to the water to be treated to perform filtration washing to activate and regenerate the manganese oxide, and Add an oxidizing agent to the water to be treated Oxidation device process is performed to the filtrate tank and the backwash water tank is housed in a single device, adding the oxidizing agent from the oxidizing unit for supplying an oxidant to the treated water stored in the backwash water tank An iron / manganese removal apparatus, characterized in that activation water adjusted to a pH of 10 or more is supplied into the filtration tank, and the activation water is closed and circulated to activate and regenerate the manganese oxide .

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