KR100361655B1 - Apparatus and method for biologically removing iron and manganese in water supply sources - Google Patents

Abstract

The present invention relates to an apparatus and a method for biologically removing iron and manganese from a water source, and specifically, aeration of the water containing iron and manganese in an aeration tank; Optionally fermenting iron and aerated treated water if the concentration of iron in the source water is high or the residence time of the aeration step is short and settles the resulting precipitate; Filtering the supernatant of the step in a first filtration tank filled with sand imparted with biological action; And filtering the filtrate discharged from the filtration step in a second filtration tank filled with activated carbon imparted with a biological action, and optimizing treatment conditions for maximizing utilization of microorganisms for oxidizing and adsorbing iron and manganese. In this way, iron and manganese can be removed economically and effectively from the water supply.

Description

Apparatus and method for biologically removing iron and manganese in water supply sources

The present invention relates to an apparatus and a method for biologically removing iron and manganese from a water source.

More specifically, the step of aeration of the purified water containing iron and manganese in the aeration tank; Optionally, when the iron concentration of the source water is high or the residence time of the aeration step is short, aging the oxide of the aerated water and settling the precipitate formed; Filtering the supernatant of the step in a first filtration tank filled with sand imparted with biological action; And it relates to a device and method for biologically removing iron and manganese in a water source comprising the step of filtering the filtered water discharged in the filtration step in a second filtration tank filled with activated carbon imparted biological action.

When iron is included in the tap water in a large amount, the iron tastes and boils out of the water, and it becomes reddish brown in clothes or equipment during washing and washing, and is also unsuitable for industrial water. In general, if the iron content is high in the water source, manganese content generally tends to be high, and in the case of manganese, when there is more than 0.15mg / l in the drinking water, an unpleasant metal odor is generated and stains occur in piping facilities or laundry. In addition, even if the amount is less than 0.3mg / ℓ based on the quality of food and drinking water, it can react with chlorine added as a disinfectant, resulting in 300-400 times the color of manganese or black deposits on the inner surface of the tube. Maintaining as low a concentration as possible (below 0.05 mg / l) is common in foreign countries as it can cause black water.

In Korea, there are few research and treatment steps for removing iron and manganese from water sources. In foreign countries, groundwater and riverside filtration are mostly removed at the physicochemical stage. Commonly applied physicochemical unit processes include aeration treatment, chemical oxidizing agent (chlorine or potassium permanganate) treatment, ozone treatment, filtration treatment using special media or general media, and are usually treated in combination. .

The aeration treatment oxidizes the divalent dissolved iron contained in raw water by aeration to precipitate insoluble ferric hydroxide (trivalent iron). Iron and manganese oxidation caused by aeration is greatly influenced by pH conditions. Less than 40 minutes is required for oxidation to trivalent iron. Manganese is not oxidized by aeration at pH 9.5 or below, so treatment is difficult under normal conditions. Therefore, the aeration treatment is expensive because it must be accompanied by a chemical treatment to maintain the pH rise conditions, there is a hassle to remove manganese by using a special filter as a post-treatment.

Oxidation of iron and manganese with an oxidizing agent such as chlorine or potassium permanganate converts it to ferric hydroxide or manganese dioxide and quickly coats the sand in the subsequent filtration step. Chlorine treatment is often used to oxidize divalent iron and manganese, and it is faster to oxidize than aeration. Iron can be easily oxidized at neutral pH, but manganese rarely oxidizes even with chlorine treatment. Potassium permanganate, on the other hand, is a powerful oxidant, capable of operating in a wide range of pH and short reaction times. However, in the case of chemical treatment, it is always cumbersome to require a post-filtration treatment step, and it is economically disadvantageous because it uses expensive oxidizing chemicals.

Ozone treatment uses ozone's strong oxidizing power to oxidize iron and manganese in a short time, but it is expensive for initial investment and maintenance, and there is a risk of discoloration of the treated water when over-injection. There is a possibility of odor generation by, and it is cumbersome to require post-stage filtration treatment rather than single treatment.

In addition, the method of the potassium permanganate treatment and ozone treatment has a disadvantage in that a large amount of sludge is made by over-oxidation, which requires frequent backwashing in the subsequent stage filtration treatment and decreases the filtration efficiency.

The method for removing iron and manganese using special media is to use special media coated with manganese dioxide (MnO ₂ ) that can adsorb and remove soluble manganese on the surface by treating zeolite or anthracite with manganese chloride and potassium permanganate. media). MediaSand's trademarks include GreenSand, Birm, and Ferrox, which are commonly referred to as manganese sand. If filtration continues, manganese sand is gradually coated with manganese oxide and the sand particles become thick and black. Therefore, if manganese sand is used continuously, adsorption capacity decreases and breakthrough occurs, thereby causing troublesome regeneration.

As described above, an object of the present invention is to provide an apparatus and method for simply and effectively removing iron and manganese in a water source by overcoming the long-term and high-cost economic disadvantages of existing treatment methods.

1 is a schematic diagram of an apparatus and method for biologically removing iron and manganese from a water source according to the present invention.

* Explanation of symbols for main parts of the drawings

1: water supply 2: aeration tank

3: reaction and precipitation tank 4: filtration tank

5: activated carbon filtration tank 6: aeration oxidized water

7: Sedimentation Sludge Removal 8: Reaction and Precipitation Supernatant

9: Filtration backwash 10: Activated charcoal backwash

11: Filtrate 11a: Filtration depth 60 cm

11b: Filtration depth 120 cm Filtrate 12: Final treated water

Figure 2a is a photograph before the microorganism acclimation of the first filtration tank filled with sand, Figure 2b is a photograph showing the appearance of a biological action to the microorganisms are applied to the first filtration tank.

Figure 3a is a photograph before the microorganisms of the second filtration tank filled with activated carbon, Figure 3b is a photo showing the appearance of the biological action is applied to the microorganisms in the second filtration tank.

The present invention provides an apparatus for removing iron and manganese from a water source comprising an aeration tank, a first filtration tank filled with biological action and a second filtration tank filled with activated carbon imparted with a biological action and / or a reaction and precipitation tank. do.

In addition, the present invention (a) iron and manganese containing aerated in the drinking water; (b) optionally aging and reacting the oxides of the aerated water when the iron concentration of the drinking water is high or the residence time of the aeration step is short, and the precipitate formed is precipitated; (c) filtering the supernatant of said step in a first filtration tank filled with sand imparted with biological action; And (d) filtering the filtered water discharged from the filtration step in a second filtration tank filled with activated carbon imparted with biological activity.

At this time, the biologically imparted filtration tank is a culture of microorganisms that oxidize, adsorb or metabolize iron and manganese by continuously introducing water containing a large amount of iron and manganese into the filtration tank.

In addition, in step (c) (d) is preferably carried out under dissolved oxygen 5.0 mg / L or more, the step (c) filtration step and (d) activated carbon filtration step is a downflow method, and Preference is given to performing backwashing with water.

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

1 is a schematic diagram of an apparatus and method for biologically removing iron and manganese from a water source according to the present invention, which includes an aeration tank 2, a sand-filled first filtration tank 4, and a biological action. A second filtration tank 5 filled with activated carbon, optionally comprising a reaction and precipitation tank 3.

First, the raw water (1) containing iron and manganese is transferred to the aeration tank (2). At this time, the aeration treatment method varies depending on the case of transport without water pressure and a sufficient water pressure by the submersible pump. The aeration treatment method can be classified into natural aeration, injection by pressure water, contact aeration, and aeration using a blower. When the water source 1 to be conveyed has a sufficient water pressure, the aeration treatment method may be a natural aeration, injection by pressure water, or contact aeration. Use the flop method.

Natural aeration method is a method of using a drop, cascade aeration, multi-stage aeration, overflow wear using aeration method, there is an advantage of simple maintenance and maintenance without the cost of facility or power. Injection by pressure water refers to a method of spray aeration by using a spraying nozzle using a pumping pressure of a pump installed in a water inlet. In addition, the contact aeration type refers to a method in which water flows from the upper part of a contact medium such as a coke to the lower part by using a spray pressure, and the air is blown by a natural ventilation or a blower from the lower part. It is a method to aeration by installing an diffuser in the room.

The ultimate purpose of the aeration treatment is to maintain the optimum conditions of microbial treatment in the filtration tanks 4 and 5 to which biological functions have been imparted, ie to supply dissolved oxygen (DO) to the filtration tank. In addition, there is an object of additionally oxidizing iron in water and removing odorous components such as volatile substances (VOCs) and hydrogen sulfide (H ₂ S).

In this case, in order to thoroughly remove iron and manganese in the filtration tanks 4 and 5, it is necessary to maintain dissolved oxygen of 5.0 mg / L or more and a redox potential of 300-400 kPa or more, so that a natural flow rate of 5 m 3 / day In this case, it is preferable to aeration at an aeration amount of 5-10 L / min or more.

The aerated aerated oxidation water (6) is a reaction and sedimentation tank (3) for selectively aging and reacting the oxides of the aerated water when the iron concentration of the purified water is high or the residence time of the aeration stage is short. Transferred. The purpose of the reaction and the installation of the settling tank 3 is for the purpose of allowing iron and manganese to sufficiently react with oxygen in the water so that some oxidized precipitates can settle, and the reaction time is preferably about 15 to 60 minutes. In the aeration treatment method, the reaction and precipitation steps may be omitted in the case of an acidic aeration that may have a certain residence time or when the iron concentration in the water supply is low.

The oxidized precipitate precipitated in the reaction and precipitation step is removed through the precipitation sludge removal (7), the reaction and precipitation supernatant (8) is transferred to the first filtration tank (4).

The first filtration tank 4 is filled with sand, and at this time, the filtration company uses general sand instead of specially manufactured sand. It is possible to remove iron and manganese at a thickness of about 1.5m, but it is desirable to set it at 1.5 ~ 2.0m in consideration of safety.

In order to impart a biological function to the sand-filled first filtration tank, the raw water containing a large amount of iron and manganese must be continuously flowed so that microorganisms having the function of removing iron and manganese from the filter sand can grow. Microorganisms that remove iron multiply rapidly and typically require a period of acclimation of 3 days to 1 month. Meanwhile, in the case of manganese, biological removal conditions are difficult and the acclimatization period of the microorganisms for removing manganese is required about 3 months (see FIG. 2).

In the filtration tank (4) to which biological function is given, oxidized iron is removed by physicochemical manure, adhesion, and contact reaction on the surface of the filtration tank, and underneath it is deposited by biological iron oxidation and adsorption of iron to the surface of the microorganism. And metabolism of iron by microorganisms, and manganese is removed further down.

In the filtration step, the filtration speed is preferably 120 to 150 m / day, and the variation in the filtration speed should be within ± 10%, and the depth of the water on the slope is preferably maintained at 60 cm or more to prevent turbidity leakage. , Sand with a uniform coefficient of 1.5 or less with a particle diameter of 1.0 to 1.5 mm is used. More preferably, sand having an equal coefficient of 1.3 or less is used.

The filtration tank (4) needs periodic backwashing (9), and at this time, air and water washing is preferable to wash the depth of the filtrate, and once every 3 to 7 days depending on the concentration of iron and manganese. It is preferable to wash to a degree.

The filtered filtration water 11 is transferred to the second filtration tank 5 which is given a biological function and filled with activated carbon. In activated carbon filtration stage, taste and odor-causing substances (2-MIB, geosmin, etc.), synthetic detergents, phenols, trihalomethane and their precursors (corrosives, etc.) that are not removed by pretreatment such as aeration, reaction, and filtration from water sources ), Applied to remove volatile organic compounds such as trichloroethylene, trace harmful substances such as pesticides, chemicals and other organic substances temporarily introduced by accidents in the upstream water source, and trace amounts of manganese not removed in pretreatment. Remove it.

The standard applied in the activated carbon filtration step (5) is based on the standard of bioactive carbon shown in the water supply facility standards, the filtration speed is preferably about 120-250m / day, the thickness of the filter layer is about 2.0m in consideration of the filtration speed, etc. Is preferred. In the activated carbon filtration step (5), the backwashing (10) method is performed by washing with air and water in order to wash the depth of the filtrate, and the backwashing cycle is preferably longer than the filtration backwashing (9) cycle.

Treatment of the source water according to the method of the present invention removes about 94% iron and about 99% manganese.

The present invention will be described in more detail with reference to the following examples. The following examples illustrate the invention, but the invention is not limited thereto.

Example 1

The riverside filtration water (I) supplied through the wells 40 meters away from the riverside was used as a water source, and the average water quality of the riverside filtration waters (II) and rivers, that is, the drift water (III) in the water wells 200m away from the riverside was used. Comparison was made with the control.

Drift Water (Ⅲ) Riverside Filtration (Ⅰ) Riverside Filtration (Ⅱ) pH 8.3 7.0 7.0 Turbidity (degrees) 12 2 or less 2 or less Chromaticity (degrees) 12 3.3 2.5 Iron (mg / l) 0.3 0.5 3.0 Manganese (mg / l) 0.05 0.9 3.2 Potassium permanganate (mg / l) 11 1.5 2.0 Ammonia-nitrogen (mg / l) 0.02 0.03 0.04 Nitric Acid-Nitrogen (mg / L) 3.0 0.2 0.07 Hardness (mg / ℓ) 78 115 - Sulfuric acid (mg / l) 46 35 32 Biological Oxygen Demand (mg / ℓ) 3.5 1.0 1.0 Chemical oxygen demand (mg / l) 6 1.2 1.1 Suspended solids (mg / ℓ) 10 1.5 2.3 Total Organic Carbon (mg / ℓ) 5.5 0.9 0.8 Total nitrogen (mg / ℓ) 3.9 0.5 0.8 Total phosphorus (mg / ℓ) 1.1 0.3 0.2 Escherichia coli (negative / 50ml) positivity Yin-yang voice General bacteria (100 CFU / ml) 1200 500 20

The experiment was performed according to the steps shown in FIG. 1 using the riverside filtration water (I) transferred through the submersible pump of the intake well. The pilot specifications configured for each step are shown in Table 2 below.

division size Standard condition Remarks Riverside Filtration (Ⅰ) Inflow 5 m ³ / day Experiment to convert inflow to 2.5, 5, 10 m ³ / day Aeration tank (2) 30cm (W) * 116cm (L) * 30cm (H) 20 minutes residence 10 ℓ / min aeration Aeration system using blower to convert aeration from 0 to 20 ℓ / min Reaction and Precipitation Tanks (3) 30cm (W) * 116cm (L) * 30cm (H) 30 min stay Up and down type Filtration tank (4) 23cm (Φ) * 200cm (H) 120m / day filtration Specifications: Biological filter, effective diameter 1.0 ~ 1.5 mm Activated Carbon Filtration Tank (5) 23cm (Φ) * 150cm (H) 120m / day filtration speed Specification: Biological activated carbon, particle size 12 × 40 (0.6 ~ 1.7mm)

Example 2

In order to confirm the removal of iron and manganese according to the change in the amount of aeration in the aeration stage, the amount of iron and manganese in the filtered water 11 of FIG. 1 by varying the amount of aeration at 0, 10, 20 l / min As a result, the iron and manganese removal efficiency was lowered when no aeration and aeration at 10 l / min, specifically 50 to 70% for iron, 0 to 30% for manganese. On the other hand, there was no difference in the removal efficiency between iron and manganese when aerated at 10ℓ / min and 20ℓ / min.

In order to determine the optimum conditions of the iron and manganese removal method according to the present invention, dissolved oxygen (mg / l) and redox in the treated water at the standard conditions (treatment flow rate 5㎥ / day, air flow rate 10ℓ / min) The potential (mV) was measured. The experiment was conducted for 6 months including the winter season from September to February.

The results are shown in Table 3 below.

division pH Water temperature (℃) Dissolved Oxygen (mg / l) Redox potential (mV) Riverside Filtration 7.5 14.0 3.1 50 Aeration tank 7.5 13.9 6.5 450 Reaction and precipitation tank 7.5 13.9 6.4 420 Filtration tank 7.5 15.4 6.2 370 Activated carbon filtration tank 7.4 15.6 5.5 330

The aeration conditions are determined by the post-filtration stage (4) and the activated carbon filtration stage (5), and the experimental results show that dissolved oxygen is more than 5.0 mg / l and redox potential (Eh) is 300-400 mV. It was confirmed that it was required to be maintained.

Example 3

In order to determine the proper filtration rate of the filtration step and the activated carbon filtration step in the present invention, the treatment flow rate was changed to 2.5, 5.0, 8.3 ㎥ / day to 60, 120, 200m / day respectively.

As a result of the change of treatment flow rate for the filtration stage, the treatment efficiency of iron, manganese, and permanganate consumption for 60m / day and 120m / day was not different, but iron was leaked at 200m / day. Therefore, the optimal filtration rate in the filtration stage is preferably 120 to 150 m / day in consideration of iron leakage.

On the other hand, in the case of activated carbon filtration step, the removal rate of iron and manganese is small according to the change of filtration rate. Especially, in case of manganese, more than 95% of manganese is stably removed even at the maximum filtration rate of 8.3㎥ / day and 200 m / day. It became. Therefore, in the case of activated carbon filtration step, it was confirmed that stable removal occurred up to about 200 ~ 250 m / day.

Example 4

In the present invention, the removal rate by filtration depth of the filtration step under standard conditions was investigated, and the results are shown in Table 4 below.

division iron manganese Remarks Riverside Filtration 0.3 0.8 1 of FIG. 1 Filtration 60cm 0.1 0.2 11a of FIG. 1 Filtration 120cm 0.09 0.15 11b of FIG. 1 Filtration Water 0.09 0.13 1 of 11

In the case of iron, the removal effect is less depending on the depth, but in the case of manganese, the higher the depth, the higher the removal efficiency.

Example 5

As a result of performing the method of the present invention with the inflow flow rate of the riverbank filtration water, which is a standard condition, the flow rate of the aeration stage 10ℓ / min, the water quality analysis by iron and manganese content is shown in Table 5 below.

division Iron (mg / l) Manganese (mg / l) Potassium permanganate consumption (mg / ℓ) Riverside Filtration 0.5 1.0 1.5 Filtration stage 0.13 (75%) 0.45 (65%) 1.1 (25%) Activated Carbon Filtration Stage 0.03 (94%) 0.01 (99%) 1.0 (30%) * () Is removal rate by raw water

As described above, in the method of removing iron and manganese from the water source, if the existing physicochemical method is used, it requires a large cost for initial facility investment, and an expensive pH regulator or oxidant is required for maintenance. It is a burden. However, in the case of using the biological method of the present invention, the installation is simple, and it does not incur the same chemical cost as the oxidizing agent, and does not incur the cost of regeneration treatment, so that maintenance is relatively easy. In particular, when the reaction and precipitation step is omitted depending on the iron concentration of the influent, the process is simplified, the treatment time is shortened, the required site is reduced, and so is economically advantageous.

In addition, when iron and manganese are removed from the source water by using the apparatus and method of the present invention, iron and manganese are removed in the biological filtration step, and some manganese and trace harmful substances are completely removed in the bioactive carbon filtration step. The efficiency is excellent.

Claims (5)

An aeration tank, a first filtration tank endowed with biological action and filled with sand, and a second filtration bath endowed with biological action and filled with activated carbon, and / or a reaction and precipitation tank, wherein the first filtration tank and the second filtration bath endowed with the biological action Is a device for removing iron and manganese from a water supply source, characterized in that the water containing a large amount of iron and manganese is continuously introduced into the filter tank to sufficiently culture microorganisms that oxidize, adsorb or metabolize iron and manganese. (a) aeration in a drinking water containing iron and manganese; (b) optionally aging and reacting the oxides of the aerated water when the iron concentration of the drinking water is high or the residence time of the aeration step is short, and the precipitate formed is precipitated; (c) filtering the supernatant of said step in a first filtration tank imparted with biological action and filled with sand; And (d) filtering the filtrate discharged from the filtration step in a second filtration tank to which biological action is imparted and filled with activated carbon, The first filtration tank and the second filtration tank to which the biological action is given are continuously supplied with water containing a large amount of iron and manganese into the filtration tank, and the cultured water source is characterized in that the microorganisms are sufficiently cultured to oxidize, adsorb or metabolize iron and manganese . Biological method of removing iron and manganese. delete The biological removal method according to claim 2, wherein the steps (c) to (d) are performed at a condition of 5.0 mg / l or more of dissolved oxygen. The biological removal method according to claim 2, wherein the (c) filtration step and (d) activated carbon filtration step are in a downflow manner, and backwashing with air and water is performed at regular intervals.