KR200231590Y1 - System for treatment of bank-filtered water - Google Patents

Abstract

The purpose of the present invention is to provide a water treatment facility for efficiently treating iron and manganese which may be a problem when the riverside filtration water, which is an alternative water source, is withdrawn from the water source.

The present invention is directed to an air treatment apparatus for treating iron contained in a river filtration water taken out of a tank, an air tank for oxidizing iron contained in the river filtration water taken in the tank, a chemical tank for oxidizing the manganese dissolved in water by introducing an oxidant into the treated water passed through the air tank, A sedimentation tank for sedimentation of manganese oxide from the water, a return line connected to the bottom of the sedimentation tank for returning the precipitated manganese oxide to the chemical tank, a membrane connected to the sedimentation tank and having a filtration membrane inside the sedimentation tank, The present invention provides a water treatment facility for river water filtration including a membrane separation tank.

Description

[0001] System for treatment of bank-filtered water [

The present invention relates to a facility for water treatment of riverside filtration water as a water source, and more particularly to a riverside filtration water treatment facility capable of efficiently removing iron and manganese contained in riverside filtration water by using an oxidizing agent and an ultrafiltration membrane.

In recent years, the imbalance in water balance has worsened globally, demand has surged more than supply, domestic conditions have been worsened, and water damage is expected. In the case of domestic water supply, most of the water is supplied to the drift water. However, securing of the raw water by the construction of the dam, which is the main water intake source, requires long time until the supply period, It has been difficult to solve difficult lighting difficulties, and the development and diffusion of alternative water sources have become urgent.

In addition, rapid economic development, transition to a highly industrialized society, and improvement of the standard of living have increased the discharge of various toxic pollutants, and the water quality of rivers has gradually deteriorated over time. In addition, due to population concentration and indiscriminate industrial complex construction, the water pollution of rivers and lakes, which are sources of water sources, is increasing, but the investment in basic environmental facilities is insufficient, and water quality pollution is getting worse over time.

Due to this situation, the method of directly taking the river water which is the current water supply source as raw water has many problems. That is, currently existing water purification plants in Korea depend on river water for most of the raw water, and when the water pollution of raw water or water contamination accident of unexpected water is very high and an accident that poisonous material flows into raw water occurs, There is no reality.

Therefore, a new water supply system is in demand and research and development for indirect water withdrawal method which removes contaminants through appropriate pretreatment without water intake directly to raw water and copes with water quality accidents of raw water.

The riverside filtration method, which has recently attracted attention as an indirect water withdrawal method, is to install water intake wells in an alluvial aquifer widely distributed in rivers, And to utilize the pollution abatement ability of alluvial deposits naturally present in rivers. That is, the polluted river water passes through this alluvial layer, and water quality is improved by filtration, adsorption, and biological decomposition.

The riverside filtration method allows river water to stay in the aquifer of the river for a long period of time and to remove the contaminants and toxins by utilizing the natural action of the natural river, thereby reducing the burden of processing in the subsequent water treatment process. This is more economical and safe than direct water intake and advanced water treatment, and is also advantageous to cope with unforeseen water quality accidents.

Riverbed filtration has many advantages as described above. However, in order to obtain high quality treated water, it is necessary to restrain the development of facilities causing soil pollution by designating the developed watershed as a protected area in preparation for groundwater pollution.

In addition, iron and manganese problems in the water source are not a problem when taking river water as a driftwater, but problems may arise in facilities that use groundwater, depleted water, and reservoir water. In other words, when the river water is taken, manganese concentration of river water is usually kept below 0.05 mg / ℓ, except for the heartbeat which frequently occurs in stratification. Generally, manganese concentration in river water is about 1/3 to be.

However, in the case of groundwater or riverside filtration, the concentration of iron and manganese is more than 10 times higher than the standard of drinking water, and the origin of manganese inflow is not clarified. Therefore, countermeasures such as identification and removal of manganese inflow are required.

Iron and manganese in raw water are mainly present in a bivalent state and are generally present in a dissolved state due to microbial action when acidic conditions or dissolved oxygen (DO) are insufficient. In addition, when the low-level water of the reservoir water lacking dissolved oxygen is collected and the river water containing a large amount of the organic matter is consumed when passing through the superficial layer of the collecting water of the submerged water, manganese contained in the lipid is eluted, And the number of reservoirs as water sources.

When the iron content is high in the water, the manganese is also often high, and when iron is contained in a large amount of tap water, it causes not only the fermentation in the water but also in the water, and also the reddish brown color in the clothing and the appliance when used for washing and washing. It becomes unsuitable for use.

In addition, in the intake facility, slime is formed on the screens, pumps, pipes, etc. by the production of iron bacteria, and clogging and clogging on the impeller of the pump causes rapid decrease of the water intake flow rate depending on the concentration of manganese, .

In the case of manganese, the presence of more than 0.15 mg / L in the drinking water causes unpleasant metal odor, brown stains in the piping facilities and laundry, and abnormal concentrations of iron / manganese bacteria (Clonothrix, Crenothrix) In addition to the generation of odor and taste, hydroxides, manganese oxide, etc. are coated on the water supply / drain pipe to decrease the water discharge capacity. Also, when the flow rate in the pipe is changed, the brown precipitate is discharged as water pollutant, which causes the generation of complaints. In addition, even if it contains less than 0.3 mg / ℓ of water quality, it reacts with chlorine which is input as a disinfectant to cause 300 ~ 400 times of chromaticity of manganese, and black deposits are formed on the inner surface of the tube, And it may cause spots on clothes or equipment.

When manganese is present together with iron, it becomes more pronounced and becomes dark brown color mixed with iron green. When manganese is contained in the water, it is preferable to keep the concentration as low as possible since it is hardly removed by ordinary water treatment.

Many methods for removing iron and manganese are used, including physical chemistry and biological methods. Recently, manganese removal processes using membrane filtration have been applied. The current iron and manganese removal technique will be described as follows.

(1) Aeration treatment

Aeration by aeration ultimately dissolves oxygen, and bivalent dissolved iron is precipitated as insoluble ferric hydroxide by aeration.

However, the oxidation of Fe (II) is dependent on oxygen partial pressure, initial iron concentration, and pH. However, there is no problem in iron oxidation at the pH condition of general water treatment process of pH 7.0, There is a problem that it is difficult to oxidize and remove by simple aeration without pH adjustment because the speed is very slow.

(2) Iron and manganese treatment by oxidizing agent (chlorine is used as oxidizing agent)

Chlorine treatment is often used to oxidize bivalent iron and manganese, and the oxidation rate is faster than that of aeration treatment.

Both iron and manganese are affected by the oxidation rate due to pH. Iron can easily be oxidized even at low pH. However, manganese is rarely oxidized at pH 9 or lower. Therefore, in order to facilitate oxidation, 9 < / RTI > For example, in order to oxidize more than 90% of manganese, pH is required to be 12 hours when alkalinity is higher than 50 mg / ℓ, and 2 to 3 hours is required when pH is 8.0.

When ammonia nitrogen is contained in the raw water, chloramine is formed by the addition of chlorine, and the oxidation rate is decreased. In this case, it is necessary to add chlorine at a breakthrough point or more to maintain free residual chlorine at about 0.5 to 1.0 mg / L.

According to recent research data, when the water temperature is below 5 ℃, the manganese oxidation reaction by chlorine is delayed. If natural organic substances such as humic acid are present, sufficient amount of chlorine is added to oxidize the manganese.

(3) Iron and manganese treatment with oxidizing agent (Potassium permanganate is used as the oxidizing agent)

Potassium permanganate is a strong oxidizing agent in Korea. It is a water treatment agent in Korea and its usage is limited. However, it can effectively oxidize manganese in a short time, and it can effectively remove manganese from manganese You can consider using it as a treatment drug.

The theoretical KMnO ₄ requirement of 0.92 mg and 1.92 mg per 1 mg of iron and manganese are respectively decreased by the catalytic action of the insoluble MnO ₂ (s) produced by the oxidation reaction at the input.

When excess amount is injected in excess of the amount required for use, permanganate ion leaks and the filtered water is colored in pink, so an appropriate amount should be supplied. Since the colloid generated during oxidation is in a stable state due to a strong negative charge, it is difficult to remove the colloidal manganese oxide from the filtration water due to the difficulty of removing it by the conventional coagulation treatment method, It is necessary to use coagulation assistant.

Potassium permanganate is a powerful oxidant and has a short reaction time in a wide pH range. At pH 7 and above, the oxidation time is 5 to 10 minutes for both iron and manganese. The potassium permanganate used for manganese treatment is used for pretreatment of manganese sulfate filtration rather than being used alone for oxidation purpose. The cost of the drug is 5 times as high as that of chlorine and the operation cost is high. Leakage and the colored water will be colored in pink. And colloidal colloidal materials, which are oxidized and colored, shorten the operation time of filter paper and lower filtration efficiency.

(4) Removal by chlorine dioxide

In recent years, chlorine dioxide has been used for disinfection, removal of odor and odor, removal of THM (trihalomethane) precursors, and oxidation of iron and manganese. Compared with chlorine, iron and manganese oxidation rate is fast, and THM is advantageous because it is effective, but it is expensive, and there is a disadvantage that the input amount is limited due to the potential toxicity of residual materials.

(5) Ozone treatment

The use of ozone only for the purpose of oxidizing bivalent iron and manganese appears to be not a good method because of other cost-effective methods. Nevertheless, in Europe, conventional ozone treatment is combined with conventional water treatment Iron and manganese are removed. It has been known empirically that the oxidation of manganese by excess ozone produces permanganate and discolourates the water of purified water.

Theoretically, 1 mg / l of ozone oxidizes 2.33 mg / l of iron and 1.14 mg / l of manganese. When the dissolved Mn ²⁺ in the raw water is oxidized, it becomes Mn ⁴⁺ (MnO 2) or Mn ⁷⁺ (MnO ₄ ^_ ) and the oxide is discolored and the oxide adheres to the contact surface wall. Ozone oxidizes manganese quickly because of its strong oxidizing power. However, since the solubility is low, it easily leaks into the atmosphere, so the injection point should be able to have sufficient water pressure.

(6) Filtration treatment (filtration treatment using manganese fiber, filtration treatment using existing filter material)

Manganese is MnO ₂ coated with zeolite or anthracite with manganese chloride and potassium permanganate which can adsorb and remove soluble Mn (II) on the surface. It is classified according to the kind of medicines. Green Sand (glauconite ), Birm, Ferox, etc. are known.

The adsorption removal reaction of soluble manganese by manganese is as follows, and the amount of manganese adsorbable per manganese manganese is 1.44 kg.

The range of the general filtration rate in this treatment is 7 to 10 m 3 / m 2 · h. The manganese filtration method is advantageous when the concentration of iron and manganese is about 1 mg / ℓ, and it can be effectively treated when the pH is kept at 7.5 or more. However, when manganese is continuously used, the adsorption ability is decreased and destruction occurs. .

The major disadvantage of the manganese filtration is that it causes a sudden loss of hydraulic head due to the oxidized oxide, which requires a high operation cost. If the pH is lowered to 7.1 or less, the adsorption capacity of manganese oxide decreases.

When the raw manganese-containing raw water is continuously added to the fire, MnO ₂ is coated on the sand or anthracite, which is a conventional filter material, to remove iron and manganese, Chlorine must be continuously injected so that residual chlorine of the order of 0.5 mg / l is retained in the filter paper effluent, since the adsorbing ability can be maintained by continuous feeding and regeneration. The removal efficiency of manganese is affected by the amount of manganese deposition on the filter media, the oxidation state of manganese and the pH of the influent.

(7) Biological treatment using microorganisms

Removal of iron and manganese by microorganisms is a method of removing iron and manganese by using iron or manganese for metabolism (oxidation and reduction) or by extracellular substances such as ECP (Extracellurar Polymer) Is a method in which iron bacteria oxidize iron and manganese dissolved in water to convert them into insoluble iron / manganese compounds and then remove them by using the ability to deposit on microbial surfaces or cells.

The microorganisms metabolizing iron and manganese are attached to the drainage pipe and the wall of the reservoir, and grow to several centimeters (cm). This material is a mixture of iron and manganese oxides and microorganisms, which reduces the permeability of the pipe and causes problems such as residual chlorine consumption, reduced dissolved oxygen in the water, and is caused by water pollution, which causes enemy water, black water and odd taste and odor do.

(8) Removal by membrane filtration

The water treatment process using membranes is a method of filtering raw water using separation phenomenon by membranes. When this membrane separation technique is used for water treatment, raw water is sieved and screened, followed by membrane separation and sterilization to obtain drinking water In addition, since the membrane structure can replace the sedimentation filter paper, the structure is simple and easy to operate as compared with other water treatment systems that do not use a membrane structure. Accordingly, the water treatment method using such a membrane separation technique is attracting attention as a next-generation water treatment method.

The film structure generally used is a hollow fiber membrane. A hollow fiber membrane is a hollow fiber membrane, such as a straw, having a hole in the middle and a fine hole on the surface.

The water treatment method using the membrane structure utilizes the property that the raw water is effectively filtered due to the specific structure of the hollow fiber as described above.

However, in the membrane separation process, as the water treatment progresses, the membrane is occluded by the material filtered by the membrane, which causes a disadvantage that the water treatment efficiency and the lifetime of the membrane deteriorate.

As described above, the above-mentioned processes have advantages and disadvantages. In fact, the riverside filtration water treatment facility uses a combination of various processes appropriately, and it is necessary to develop a water treatment facility for more efficient removal of iron and manganese contained in the riverside filtered water It is true.

Accordingly, the present invention provides a water treatment facility for efficiently treating iron and manganese which may be a problem when the riverside filtration water, which is an alternative water source, is taken as a water source, have.

Another object of the present invention is to provide a river filtration water treatment facility capable of reducing the damage of secondary toxicity of a potential substance due to chemical reaction by reducing the amount of oxidizing agent used for water treatment.

Another object of the present invention is to provide a water treatment facility for river water filtration which can prevent clogging of membrane and prolong its service life in a water treatment facility using membrane filtration.

FIG. 1 is a schematic view showing a process flow of a river water filtration water treatment facility according to the present invention.

Description of the Related Art [0002]

10: air reaction tank 20: chemical tank

30: settling tank 40: return line

50: membrane separation tank 51: membrane

52: Continuous flow line

In order to achieve the above-mentioned object, the water treatment facility according to the present invention comprises an air reaction tank for oxidizing iron contained in supplied river-side filtered water, a chemical tank for oxidizing manganese dissolved in water A sedimentation tank for sedimenting manganese oxide from the treated water, a return line for returning the precipitated manganese oxide to the chemical tank, and a membrane separation tank for separating the treated water through the sedimentation tank.

The air reactor may be operated by bringing filtered water into contact with air to oxidize the water, and installing only a spray device using the difference in height of the water pumped in the water inlet.

The chemical tank may have a stirrer inside for rapid stirring.

A variety of chemicals such as chlorine, potassium permanganate and the like can be used as chemicals to be introduced into the chemical tank, and chlorine dioxide is used to reduce the contact time.

The sedimentation tank can be a natural sedimentation type.

The return line is a line for conveying the precipitated manganese oxide in the settling tank by connecting the bottom of the settling tank and the chemical tank, and a control valve for adjusting the opening and closing amount of the line is installed on one side.

Membrane separation chambers are equipped with various membranes for water treatment. Reverse osmosis (RO), ultrafiltration (UF), microfiltration (MF), electrodialysis ED). In the present invention, it is preferable to use an ultrafiltration membrane useful for removing colloidal macromolecules or suspended solids.

Hereinafter, one embodiment of the present invention will be described in detail with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic view showing a water treatment facility for river water filtration according to the present invention; FIG.

According to the above-mentioned drawings, the present invention is characterized in that the present invention comprises an air reaction tank (10) for oxidizing iron dissolved in riverside filtration water by being fed with riverside filtration water supplied from a river or a river, A chemical tank (20) for introducing chlorine dioxide into the treated water, which is connected to the air tank through the connection pipe, to convert the dissolved manganese in the water into an oxide form, and a chemical tank A return line 40 for returning the precipitated manganese oxide to the chemical tank, which is connected between the bottom of the settling tank and the air tank, and the connection pipe of the chemical tank, and a connection pipe to the settling tank And a membrane separation tank 50 for separating the manganese oxide from the treated water through the settling tank.

In this case, the respective groups are sequentially connected to a connection pipe, and the river-side filtered water supplied from the water collection is dissolved in the filtration water while passing through the air reaction tank 10, the chemical tank 20, the settling tank 30, It is possible to discharge iron and manganese contained therein.

Hereinafter, the operation of each treatment tank will be described in more detail.

In the air reaction tank 10, iron is oxidized by spraying the water pumped in the intake pipe.

Oxidation by aeration ultimately dissolves oxygen and is effective when present as divalent dissolved iron or ferrous bicarbonate (Fe (HCO ₃ ) ₂ ) under normal conditions (pH 7) ≪ / RTI > In addition, aeration can remove free carbonic acid, hydrogen sulfide, volatile matter (VOC _S ) and provide dissolved oxygen in the water.

The kinetics for the oxidation of Fe (II) by oxygen are as follows.

here, : rate of iron (II) oxidation, mol / ℓ · min

k: reax. rate const. , 8.0 (± 2.5) × 10 ¹³ L ² / min · atm · mol ² at 20.5 ° C.

pO ₂ : partial pressure of oxygen, atm

[OH ^- ]: hydroxide ion concentration, mol / l

[Fe ²⁺ ]: iron (II) concentration, mol / l

In the chemical tank 20, the oxidizing action of manganese by chlorine dioxide to be introduced and the catalytic action by manganese oxide (to be described later) re-introduced from the settling tank 30 are performed.

Also, by providing a stirrer (not shown) in the chemical tank 20, the reaction can be promoted by rapidly stirring the filtered water and the oxidant.

Iron, and manganese, the theoretical requirements for chlorine dioxide are 1.2 mg and 2.44 mg, respectively.

Fe (OH) _3 + ClO_2 ^ - `+ 3H ^ 2 + + ClO_2 +

MnO2 (s) + 2ClO_2 ^ - + 4H ^ + where the oxidation rate of iron and manganese is faster than that of chlorine, and the reduction of THM (trihalomethane) The advantage is that it is effective, but it is expensive and there is a disadvantage that it is limited by the potential toxicity of the residual material, so its use should be reduced. The structure for reducing the use amount of chlorine dioxide can be achieved as a manganese oxide which is introduced into the chemical tank 20 through the settling tank 30, the return line 40, and the return line, which will be described later.

The manganese oxide separated from the treated water in the sedimentation tank (30) for a predetermined period of time is separated from the manganese oxide And the supernatant is sent to the next membrane separator (50).

The precipitated manganese oxide is reintroduced into the chemical tank 20 through the return line 40 connected to the bottom of the sedimentation tank 30. At this time, the control valve 41 installed at one side of the return line 40 is adjusted to control the amount of manganese oxide to be introduced.

The manganese oxide introduced into the chemical tank 20 through the return line 40 contributes to the oxidation of manganese through the oxidation catalyst function, thereby reducing the amount of chlorine dioxide input.

In other words, manganese should have a pH of 9.5 or higher in order to produce oxidized precipitates to manganese dioxide (MnO ₂ ), but the action of oxidizing the dissolved manganese by catalytic oxidation of manganese dioxide is more important than the formation reaction of dioxide precipitate . Oxidation is accelerated by catalytic action of oxidized manganese oxide, and the oxidation reaction occurs more rapidly as the pH is higher. If the pH is 7.0 days, but Mn ²⁺ uptake 0.3㎎ for MnO ₂ 1㎎ a pH of 8.0 when the high about 2.5 times compared to the case where pH is in the 7.0 to absorption 0.75㎎ Mn ²⁺ / ㎎MnO _2.

The reaction rate of Eq. (1.1) and (1.3) is slow, whereas the reaction rate of Eq. (1.2) is relatively fast. This mechanism is based on the removal of Mn (II) by the catalytic action of oxidized manganese oxide when the oxidizing agent is used to oxidize the dissolved form of Mn (II) to Mn (IV) .

The stoichiometric reaction equation for oxygen in iron and manganese is as follows. The theoretical oxygen demand for iron and manganese is 0.14 mg and 0.29 mg, respectively.

1, the return line 40 branches off from one side to form a drain line 42, and the precipitated manganese oxide is injected into the chemical tank and drained through a drain line to be disposed of .

The membrane separation tank 50 is for separating the manganese component from the supernatant through the settling tank 30 and has a structure in which an ultrafiltration membrane 51 is installed therein.

Here, the term "membrane" refers to a liquid or solid membrane capable of separating a mixture by selectively passing a specific component, and the physical and chemical properties of the membrane determine the exchange rate of matter and energy. The membrane, which is commonly referred to in the separation process, is characterized by having selectivity for the material. Separation of materials using the difference in the rate of movement of these materials to the membrane is referred to as membrane-separation.

Therefore, the supernatant passing through the settling tank 30 is filtered through oxidized iron and manganese while passing through the separation membrane in the membrane separation tank 50, and eventually separated.

Reference numeral 52, which is not shown, is a continuous flow line for continuously crossing the supernatant introduced into the membrane separation tank into the settling tank, and the supernatant is continuously treated through the membrane while mutually crossing the membrane separation tank and the settling tank.

As described above, the present invention proposes a new water treatment facility for separating manganese dioxide produced by converting dissolved manganese by an oxidation reaction using an ultrafiltration membrane (UF) using chlorine dioxide as an oxidizing agent.

The raw water including dissolved manganese and the chemical tank into which the oxidizing agent is injected are transported to the manganese dioxide produced through the oxidation reaction and recovered by the solid-liquid separation to adsorb / remove the soluble manganese, and also used as a catalyst for the oxidation reaction.

The manganese converted into manganese dioxide through the catalytic oxidation and adsorption reaction reaches several tens of nanometers when the particle size is colloidal, and when the particles are grown for a long time, the particle size becomes several micrometers when redispersed. Therefore, when colloid and particulate manganese dioxide of this size coexist, it is possible to easily perform solid-liquid separation using an ultrafiltration membrane.

On the other hand, in the case where the conditions capable of sufficiently growing the manganese dioxide particles produced by the oxidation reaction are provided at the upstream side of the membrane separation step, a considerable amount of manganese dioxide is subjected to solid-liquid separation by sedimentation and this is subjected to adsorption of a dissolved manganese The reaction efficiency can be maximized.

The sludge (manganese dioxide particles) is concentrated and accumulated in the reaction system in accordance with the passage of the operation time of the whole process, which is discarded through a separate line.

While illustrative embodiments of the present invention have been shown and described, various modifications and alternative embodiments may be made by those skilled in the art. Such variations and other embodiments will be considered and included in the appended claims, all without departing from the true spirit and scope of the invention.

As described above, according to the present invention, it is possible to minimize the area occupied by the apparatus based on the oxidant and the membrane, thereby improving the economic efficiency in a place where the land cost is high.

In addition, it has an advantage of being easy to operate because automatic operation is possible.

In addition, it is possible to reduce the amount of the oxidizing agent used for the oxidation catalysis by the manganese dioxide, thereby reducing the cost required for the water treatment and reducing the secondary pollution caused by the oxidizing agent.

Further, the first precipitate separation of the manganese oxide has an effect of further extending the life of the separation membrane.

Claims (6)

An air reaction tank for oxidizing iron contained in the supplied riverside filtered water; A chemical tank for oxidizing the manganese dissolved in water by introducing an oxidant into the treated water passed through the air reactor; A settling tank for precipitating and separating the manganese oxide from the treated water through the chemical tank; A return line connected to the bottom of the settling tank for returning the settled manganese oxide to the chemical tank; A membrane separation tank connected to the sedimentation tank and provided with a filtration membrane therein for separating the treated water through the sedimentation tank; A water treatment facility for river water filtration. [2] The water treatment system according to claim 1, wherein the air reaction tank is provided with a spray device to oxidize air by dispersion of air. The river water filtration water treatment system according to claim 1, wherein the oxidant is chlorine dioxide. [2] The water treatment system according to claim 1, wherein the chemical tank further comprises an agitator therein. The water treatment system according to claim 1, wherein the filtration membrane is an ultrafiltration membrane (UF). The water treatment plant for river water filtration according to claim 1, characterized in that slow stirring or coagulant is added for sedimentation separation of manganese dioxide.