WO2018230998A1 - System and method for treating underground water synthetically contaminated by heavy metal and microorganism - Google Patents

System and method for treating underground water synthetically contaminated by heavy metal and microorganism Download PDF

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WO2018230998A1
WO2018230998A1 PCT/KR2018/006773 KR2018006773W WO2018230998A1 WO 2018230998 A1 WO2018230998 A1 WO 2018230998A1 KR 2018006773 W KR2018006773 W KR 2018006773W WO 2018230998 A1 WO2018230998 A1 WO 2018230998A1
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groundwater
iron
arsenic
heavy metal
microorganisms
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PCT/KR2018/006773
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French (fr)
Korean (ko)
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오참뜻
지상우
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한국지질자원연구원
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D35/00—Filtering devices having features not specifically covered by groups B01D24/00 - B01D33/00, or for applications not specifically covered by groups B01D24/00 - B01D33/00; Auxiliary devices for filtration; Filter housing constructions
    • B01D35/02—Filters adapted for location in special places, e.g. pipe-lines, pumps, stop-cocks
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/28—Treatment of water, waste water, or sewage by sorption
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/28—Treatment of water, waste water, or sewage by sorption
    • C02F1/281—Treatment of water, waste water, or sewage by sorption using inorganic sorbents
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/46—Treatment of water, waste water, or sewage by electrochemical methods
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/52—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/58—Treatment of water, waste water, or sewage by removing specified dissolved compounds
    • C02F1/62—Heavy metal compounds
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2101/00—Nature of the contaminant
    • C02F2101/10—Inorganic compounds
    • C02F2101/103—Arsenic compounds
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2103/00—Nature of the water, waste water, sewage or sludge to be treated
    • C02F2103/06—Contaminated groundwater or leachate

Definitions

  • the present invention relates to a technology for reducing environmental pollution, and more particularly, to a groundwater treatment technology for treating groundwater complexly contaminated by heavy metals and microorganisms.
  • Arsenic acts as a hazard to all living things, including humans. For example, in Bangladesh and Vietnam, arsenic-contaminated groundwater was used as drinking water.
  • Arsenic is caused by human activity, such as industrial wastewater, but it may occur naturally due to geological characteristics. Arsenic is highly toxic and must be treated highly until the concentration in water reaches approximately 10 ⁇ g / L. In addition, if arsenic is naturally contained in the groundwater by geological origin, it is not easy to treat because the range of occurrence is very wide.
  • Arsenic is generally present in the water at +3 and +5 valences, and various species such as redox potential, pH, and iron sulfide in the soil change the form of the species.
  • FIGS. 1 and 2 The relative ratios of each arsenic species with respect to pH are shown in FIGS. 1 and 2.
  • 1 and 2 is a table showing the ratio of each arsenic species according to the pH conditions
  • Figure 1 is a table for trivalent arsenic species
  • Figure 2 is a table for pentavalent arsenic species.
  • arsenic has a reduced species of +3 as arsenic rather than +5 as arsenic in reducing conditions, so that adsorption energy is relatively reduced. Furthermore, below pH 9.22 in water, most of the +3 arsenic is present in the form of H 3 AsO 3 is not charged.
  • the non-charged + 3-valent arsenic ions have a relatively increased mobility in groundwater, making it difficult to adsorb. That is, +5 arsenic is strongly adsorbed on soil or sediment, while +3 is reduced to arsenic, which is easily desorbed in adsorption state, making it difficult to adsorb. Furthermore, +3 arsenic is fatal because it has higher toxicity to life including human body than +5 arsenic.
  • groundwater is frequently found to be contaminated with microorganisms along with heavy metals such as arsenic. Due to insufficient sewage facilities, wastewater from human and livestock activities flows into groundwater. Filters may be installed to sterilize microorganisms, and solar sterilization may be used. While these techniques can serve as a countermeasure against microorganisms, they are limited in treating arsenic.
  • the present invention is to solve the above problems, to provide a complex contaminated water treatment system and method capable of simultaneously treating the ground water contaminated with microorganisms with heavy metals, including arsenic, can be produced in a small scale through a simple process
  • the purpose is.
  • Complex contaminated groundwater treatment system for achieving the above object, including a reaction vessel for receiving ground water, and the negative electrode and iron material positive electrode installed in the reaction tank and a power supply for applying electricity to the positive electrode and negative electrode, An electrochemical reaction tank in which the iron is oxidized and eluted, the dissolved oxygen in ground water oxidizes divalent iron to trivalent iron and an anaerobic environment is formed; An aeration tank accommodating the groundwater discharged from the electrochemical reactor and supplying oxygen to precipitate iron contained in the groundwater in hydroxide form, wherein the hydroxide form iron is adsorbed and co-precipitated with heavy metals in the groundwater; And a filtration tank for separating the groundwater discharged from the aeration tank and the sediment with each other.
  • a process for removing microorganisms by using an electrochemical reaction to elute iron which is a substance for removing arsenic, and dissolved oxygen is removed to form an anaerobic environment.
  • the groundwater complex contaminated by heavy metals and microorganisms can be purified to a drinking level.
  • the specific surface area of iron is increased by elution without using solid iron as it is, which has a great advantage in adsorbing and co-precipitation of arsenic.
  • electrochemical reactions not only removes arsenic, but also by using an anaerobic environment that can produce microbial removal in one process.
  • groundwater will be cleaned and used as drinking water in areas with insufficient infrastructure such as water supply facilities.
  • FIG. 1 and 2 is a table showing the ratio of each arsenic species according to the pH conditions
  • Figure 1 is a table for trivalent arsenic species
  • Figure 2 is a table for pentavalent arsenic species.
  • FIG. 3 is a schematic flowchart of a method for treating complex contaminated groundwater according to an embodiment of the present invention.
  • Figure 4 is a schematic diagram of a complex contaminated groundwater treatment system according to an embodiment of the present invention.
  • FIG. 5 and 6 are graphs showing changes in the number of microbial contaminants in groundwater (FIG. 5) and groundwater quality (FIG. 6) according to current densities as a result of experimenting with the present invention.
  • FIG. 13 and 14 show the arsenic removal rate (FIG. 13) and turbidity change (FIG. 14) in groundwater with time as a result of experimenting with the present invention.
  • 15 and 16 show the result of performing the same experiment as in FIGS. 13 to 14 by increasing the raw water inflow.
  • Complex contaminated groundwater treatment system for achieving the above object, including a reaction vessel for receiving ground water, and the negative electrode and iron material positive electrode installed in the reaction tank and a power supply for applying electricity to the positive electrode and negative electrode, An electrochemical reaction tank in which the iron is oxidized and eluted, the dissolved oxygen in ground water oxidizes divalent iron to trivalent iron and an anaerobic environment is formed; An aeration tank accommodating the groundwater discharged from the electrochemical reactor and supplying oxygen to precipitate iron contained in the groundwater in hydroxide form, wherein the hydroxide form iron is adsorbed and co-precipitated with heavy metals in the groundwater; And a filtration tank for separating the groundwater discharged from the aeration tank and the sediment with each other.
  • the heavy metal comprises especially arsenic and the microorganism is an aerobic bacterium including Escherichia coli.
  • both the positive electrode and the negative electrode use an iron material.
  • the inlet is formed at the bottom of the inlet is formed in the upper portion so as to form a bottom-up flow, it is preferred that a filter for filtering the sediment between the inlet and the outlet.
  • the method for treating the groundwater complex contaminated with heavy metals and microorganisms according to the present invention, (a) by putting a positive electrode and a negative electrode of the iron material in the groundwater to perform an electrochemical reaction, so that iron is eluted into the groundwater, Dissolved oxygen in the ground water reacts with iron to create an anaerobic environment to remove microorganisms; (b) supplying oxygen to the ground water to precipitate dissolved iron in hydroxide form, and removing heavy metals in the ground water by adsorbing and co-precipitation to iron in hydroxide form during the precipitation of iron; And (c) separating the sediment and the supernatant from each other in the groundwater.
  • the present invention relates to a method and system for purifying groundwater complex contaminated with arsenic and microorganisms.
  • the contaminant to be removed in the present invention is not limited to arsenic, but may be expanded to other heavy metals having similar physical and / or chemical behaviors to arsenic.
  • the main subject to be treated in the present invention is groundwater, but is not necessarily limited to groundwater, it is revealed in advance that it can include various types of water resources contaminated with heavy metals and bacteria.
  • FIG 3 is a schematic flowchart of a complex contaminated groundwater treatment method according to an embodiment of the present invention
  • Figure 4 is a schematic diagram of a complex contaminated groundwater treatment system according to an embodiment of the present invention.
  • Complex contaminated groundwater treatment method should be carried out with the process of removing arsenic, the process of removing microorganisms by creating an anaerobic environment in the groundwater.
  • the above two processes must be performed in a simple process.
  • an electrochemical reaction was introduced to remove arsenic, and at the same time, an anaerobic environment was developed to remove microorganisms.
  • the treatment method according to the present invention is largely made of three steps for this purpose is provided with a system.
  • the first step is to remove arsenic as a substance to remove arsenic through electrochemical reactions and to remove dissolved oxygen from groundwater to form groundwater into an anaerobic environment.
  • the first step is implemented by the electrochemical reactor 10 of the complex contaminated groundwater treatment system 100 according to the present invention.
  • the electrochemical reaction vessel 10 is a reaction vessel for accommodating groundwater, and the positive electrode 11 and the negative electrode 12 are installed in the spaced apart from each other.
  • the positive electrode 11 and the negative electrode 12 are electrically connected to the power supply unit 13.
  • an iron electrode is used as the positive electrode 11, and an iron electrode is also used as the negative electrode 12.
  • the negative electrode may be used as an electrode of a material other than iron.
  • the positive electrode 11 When a current is applied, the positive electrode 11 is oxidized in the positive electrode 11 and eluted into groundwater as shown in Equations 1 and 2 below to generate electrons.
  • the electrons are converted to gas by reducing hydrogen ions around the negative electrode 12 as in Scheme 3.
  • Oxidation reaction is mainly in the form as shown in Scheme 1, so that the dissolved iron in the groundwater is mainly divalent.
  • Fe (s) Fe 2+ + 2e - ( - 0.44V) ... Scheme 1 (positive electrode)
  • Fe (s) Fe 3+ + 3e - ( - 0.04V) ... Scheme 2 (positive electrode)
  • the divalent iron is converted to the hydroxide form as shown in Schemes 4-6 below to precipitate in a solid state.
  • Fe (OH) 3 FeO (OH) (s) + H 2 O ...
  • iron is precipitated as goethite or lepidocrocite in the form of FeO (OH).
  • iron is widely used as an adsorbent of contaminants, and mainly used in the solid state, for example, iron balls or powder.
  • the specific surface area becomes very wide.
  • the increased specific surface area means that the area where arsenic can be adsorbed or the space where arsenic can be co-precipitated in combination with iron is significantly increased. It is expected that there will be more than a few orders of magnitude difference in the removal of arsenic from the use of solid iron as an adsorbent.
  • oxygen consumption and ORP decrease means that the groundwater in the electrochemical reactor is made into the anaerobic environment, and the aerobic bacteria in the groundwater are lost and removed in the anaerobic environment.
  • ORP redox potential
  • oxygen consumption and ORP decrease means that the groundwater in the electrochemical reactor is made into the anaerobic environment, and the aerobic bacteria in the groundwater are lost and removed in the anaerobic environment.
  • oxygen consumption and ORP decrease means that the groundwater in the electrochemical reactor is made into the anaerobic environment, and the aerobic bacteria in the groundwater are lost and removed in the anaerobic environment.
  • oxygen consumption and ORP decrease means that the groundwater in the electrochemical reactor is made into the anaerobic environment, and the aerobic bacteria in the groundwater are lost and removed in the anaerobic environment.
  • oxygen consumption and ORP decrease means that the groundwater in the electrochemical reactor is made into the anaerobic environment, and the aerobic bacteria in the groundwater are lost and removed in the anaerobic
  • iron is precipitated in the form of hydroxide using the electrochemical reaction tank 10, and after removing microorganisms in the groundwater, a process for removing arsenic is performed in earnest.
  • the second process is the removal of arsenic in groundwater by iron hydroxide or coprecipitation with iron hydroxide. This process is performed in the aeration tank 20. Groundwater and some sediment contained in the electrochemical reaction tank 10 are all transferred to the aeration tank 20. Then, oxygen is supplied to the aeration tank 20.
  • the hydroxide form iron precipitates in the solid state by adsorption and co-precipitation with arsenic.
  • iron should first be precipitated in the form of a hydroxide. Since the more iron hydroxide precipitated, the more arsenic co- precipitates or adsorbs together, the arsenic removal rate depends on the amount of iron hydroxide precipitated.
  • one of the important conditions for iron to precipitate into hydroxide is the presence of oxygen. This is because divalent iron eluted from the iron electrode meets with oxygen and is converted into trivalent iron and precipitates as a hydroxide. Then, by supplying air to the previous electrochemical reactor, the precipitation of iron can be accelerated. However, supplying oxygen is undesirable since it creates an aerobic environment with respect to the removal of microorganisms.
  • the electrochemical reactor 10 oxidizes the divalent iron by dissolved oxygen in the groundwater and focuses on the removal of microorganisms. When anaerobic conditions are formed and all microorganisms are removed, oxygen is now supplied from the aeration tank 20 to accelerate the precipitation of iron and remove arsenic in the process.
  • the present embodiment uses a bottom-up filtration tank. That is, in the aeration tank 20, the ground water and the sediment are transferred together to the filtration tank 30, and the ground water and the sediment are introduced through the inlet 31 formed in the lower portion of the filtration tank 30, and the outlet port provided in the upper portion of the filtration tank 30 ( Through 32). And the filter 33 is provided in the middle of the filtration tank 30.
  • Solid precipitate containing arsenic does not pass through the filter 33, and only groundwater in the liquid state from which arsenic has been removed may pass through the filter 33.
  • the solid precipitate is forced downward by its own weight, so transport is limited.
  • a flocculant or the like may be selectively added to cause the precipitates to agglomerate with each other to increase their own weight.
  • both arsenic and microorganisms can be removed from the groundwater, and the groundwater is expected to be drinkable as drinking water after the purification process is completed.
  • the sample used in the experiment was taken in Vietnam and was contaminated with bacteria such as heavy metals containing arsenic and E. coli.
  • An electrochemical reactor was installed and the water quality of the groundwater sample was investigated according to the current density, and the results are shown in the graphs of FIGS. 5 and 6. 5 and 6 are the results of the electrochemical reaction for 10 minutes on the sample 370ml.
  • 10 to 12 show the result of fixing the current density at 0.343 mA / cm 2 . 10 to 12, the same results as in FIGS. 7 to 9 were confirmed.
  • results of arsenic removal rate and turbidity are shown in FIG. 13.
  • FIG. 13 it was confirmed that the initial arsenic concentration was lowered below 10 ⁇ g / L of drinking water in the test after 10 minutes at 376 ⁇ g / L, and the turbidity of the groundwater was also significantly reduced.
  • FIG. 14 it can be seen that E. coli and aerobic fines are almost completely removed when the reaction time passes 100 minutes.
  • FIGS. 14 and 15 are repeated the previous experiment, but increased the raw water inflow to 1.1ton / day. 14 and 15 also confirmed the same results as the previous arsenic removal rate, turbidity reduction rate and microbial removal rate.
  • a process for removing microorganisms by eluting iron which is a substance for removing arsenic through an electrochemical reaction, and removing dissolved oxygen to form an anaerobic environment is introduced.
  • the groundwater complex contaminated by heavy metals and microorganisms can be purified to a drinking level.
  • the specific surface area of iron is increased by elution without using solid iron as it is, which has a great advantage in adsorbing and co-precipitation of arsenic.
  • electrochemical reactions not only removes arsenic, but also by using an anaerobic environment that can produce microbial removal in one process.
  • groundwater will be cleaned and used as drinking water in areas with insufficient infrastructure such as water supply facilities.

Abstract

The present invention relates to an environmental treatment technology for purifying underground water synthetically contaminated by a heavy metal and a microorganism to a drinkable level. In the present invention, an electrochemical reaction is used to elute divalent iron, and the divalent iron is then reoxidized to trivalent iron and precipitated as hydroxide. During this process a heavy metal such as arsenic is adsorbed and coprecipitated to be removed. Particularly, while the electrochemical reaction is performed, an anaerobic environment is formed in the underground water, so that a microorganism such as Escherichia coli is removed together. In the present invention, oxygen is supplied after removal of the microorganism, thereby further activating coprecipitation and adsorption of arsenic.

Description

중금속 및 미생물 복합 오염 지하수 처리시스템 및 처리방법Heavy Metal and Microbial Contaminated Groundwater Treatment System and Treatment Method
본 발명은 환경 오염 저감기술에 관한 것으로서, 특히 중금속과 미생물에 의해서 복합 오염되어 있는 지하수를 처리하기 위한 지하수 처리기술에 관한 것이다. The present invention relates to a technology for reducing environmental pollution, and more particularly, to a groundwater treatment technology for treating groundwater complexly contaminated by heavy metals and microorganisms.
비소는 인간을 비롯한 모든 생명체에 대하여 위해 물질로 작용한다. 예컨대 방글라데시와 베트남에서 비소로 오염된 지하수를 식수로 음용하여 문제가 된 사례가 있다. Arsenic acts as a hazard to all living things, including humans. For example, in Bangladesh and Vietnam, arsenic-contaminated groundwater was used as drinking water.
비소는 산업폐수와 같은 인간의 인위적인 활동에 의해 발생하기도 하지만, 지질학적인 특성에 기인하여 자연적으로 발생하기도 한다. 비소는 독성이 강해서 수중 농도가 대략 10μg/L 수준으로 될 때까지 고도로 처리해야 한다. 또한 비소가 지질학적인 기원에 의해 자연적으로 지하수에 포함되는 경우 그 발생 범위가 매우 광범위하므로 처리하기 쉽지 않다. Arsenic is caused by human activity, such as industrial wastewater, but it may occur naturally due to geological characteristics. Arsenic is highly toxic and must be treated highly until the concentration in water reaches approximately 10 μg / L. In addition, if arsenic is naturally contained in the groundwater by geological origin, it is not easy to treat because the range of occurrence is very wide.
비소는 일반적으로 수중에서 +3가와 +5가로 존재하는데 산화-환원 전위, pH, 토양 내 철 황화물 등과 같은 다양한 변수에 의해 비소가 존재하는 종의 형태가 달라진다. Arsenic is generally present in the water at +3 and +5 valences, and various species such as redox potential, pH, and iron sulfide in the soil change the form of the species.
pH 에 따른 각 비소종의 상대적인 비율은 도 1 및 도 2에 나타나 있다. 도 1 및 도 2는 pH 조건에 따른 각 비소종의 비율을 나타낸 표로서, 도 1은 3가 비소종에 대한 표이며, 도 2는 5가 비소종에 대한 표이다. The relative ratios of each arsenic species with respect to pH are shown in FIGS. 1 and 2. 1 and 2 is a table showing the ratio of each arsenic species according to the pH conditions, Figure 1 is a table for trivalent arsenic species, Figure 2 is a table for pentavalent arsenic species.
도 1 및 도 2를 참조하면, 일반적으로 비소는 환원 조건에서는 +5가 비소로 존재하기 보다는 환원된 종인 +3가 비소로 존재하게 되어 상대적으로 흡착 에너지가 감소하게 된다. 더욱이 수중 pH 9.22 미만에서는 대부분 +3가 비소는 H3AsO3 의 형태로 존재하게 되어 전하를 띄지 않는다. 전하를 갖지 않는 +3가 비소 이온은 지하수 내 이동성(mobility)이 상대적으로 증가하여 흡착이 힘들어진다. 즉 +5가 비소는 토양이나 침전물에 강하게 흡착되는 반면, +3가 비소로 환원되면 흡착상태에서 쉽게 탈착되어 흡착처리하기 어렵게 된다. 더욱이 +3가 비소는 +5가 비소에 비하여 인체를 포함한 생명체에 미치는 독성이 높아 치명적이라는 특징이 있다. Referring to FIGS. 1 and 2, in general, arsenic has a reduced species of +3 as arsenic rather than +5 as arsenic in reducing conditions, so that adsorption energy is relatively reduced. Furthermore, below pH 9.22 in water, most of the +3 arsenic is present in the form of H 3 AsO 3 is not charged. The non-charged + 3-valent arsenic ions have a relatively increased mobility in groundwater, making it difficult to adsorb. That is, +5 arsenic is strongly adsorbed on soil or sediment, while +3 is reduced to arsenic, which is easily desorbed in adsorption state, making it difficult to adsorb. Furthermore, +3 arsenic is fatal because it has higher toxicity to life including human body than +5 arsenic.
비소로 오염된 지하수를 정화하기 위한 다양한 기술들이 개발되어 왔으며, 이들 중에서 흡착에 의한 제거 기술과 역삼투압 기술(RO, Reverse Osmosis)이 널리 활용되고 있다. 그러나 흡착 기술은 처리 수량이 크지 않고 비소 농도가 높아질수록 효율이 큰 폭으로 감소한다는 약점이 있다. 또한 역삼투압 기술은 역세수가 많이 필요하고 불순물이 있는 경우 효율이 감소한다는 단점이 있다. 이에 지하수 내 존재하는 비소를 보다 효과적으로 처리할 수 있는 기술의 개발이 요청되고 있다. Various techniques have been developed for the purification of arsenic-contaminated groundwater, among which removal techniques by adsorption and reverse osmosis (RO) techniques are widely used. However, the adsorption technique has a weak point that the efficiency is greatly reduced as the treatment yield is not large and the arsenic concentration is increased. In addition, reverse osmosis technology has a disadvantage in that a large number of backwash water is required and the efficiency is reduced when there are impurities. Accordingly, there is a demand for the development of a technology that can effectively treat the arsenic present in the groundwater.
한편, 동남아시아나 아프리카와 같이 하수 시설이 잘 갖춰지지 않은 지역에서는 지하수가 비소 등의 중금속과 함께 미생물로 오염되어 있는 경우가 빈번히 발견된다. 하수시설이 충분하지 않은 관계로 사람과 가축의 활동에 의해서 발생한 폐수가 지하수로 유입되며 나타나는 현상이다. 미생물을 살균 처리하기 위해 필터를 설치하기도 하며, 태양광을 이용한 살균이 이용되기도 한다. 이러한 기술들은 미생물에 대한 대책으로는 기능할 수 있지만, 비소를 처리하기에는 한계가 있다. On the other hand, in areas with poor sewage facilities such as Southeast Asia and Africa, groundwater is frequently found to be contaminated with microorganisms along with heavy metals such as arsenic. Due to insufficient sewage facilities, wastewater from human and livestock activities flows into groundwater. Filters may be installed to sterilize microorganisms, and solar sterilization may be used. While these techniques can serve as a countermeasure against microorganisms, they are limited in treating arsenic.
결국, 비소와 미생물로 복합적으로 오염된 지하수를 정화처리하기 위해서는 복합 공정이 요구되는데, 복합 공정을 구현하기 위해서는 플랜트의 규모가 커져야 한다. 그러나 전력망이나 도로 등 인프라 시설이 충분하지 않은 지역에서는 중앙집중식의 대규모 플랜트를 설계하는 것은 용이하지 않다. 소규모이며, 에너지 투입이 최소화될 수 있는 처리설비가 요청된다. As a result, a complex process is required to purify the groundwater contaminated with arsenic and microorganisms, and the scale of the plant must be increased to implement the complex process. However, it is not easy to design centralized large-scale plants in areas with insufficient infrastructure such as power grids and roads. There is a need for treatment equipment that is small and that can minimize energy input.
본 발명은 상기한 문제점을 해결하기 위한 것으로서, 비소를 포함한 중금속과 함께 미생물로 복합 오염된 지하수를 동시에 처리할 수 있으며, 간단한 공정을 통해 소규모 설비로 제작가능한 복합 오염수 처리시스템 및 방법을 제공하는데 그 목적이 있다. The present invention is to solve the above problems, to provide a complex contaminated water treatment system and method capable of simultaneously treating the ground water contaminated with microorganisms with heavy metals, including arsenic, can be produced in a small scale through a simple process The purpose is.
상기 목적을 달성하기 위한 본 발명에 따른 복합 오염 지하수 처리시스템은,지하수를 수용하는 반응조와, 상기 반응조에 설치되는 음전극과 철 소재의 양전극 및 상기 양전극과 음전극에 전기를 인가하는 전원부를 포함하여, 상기 양전극에서는 철이 산화되어 용출되며, 지하수 내 용존산소가 2가 철을 3가 철로 산화시키며 혐기성 환경이 조성되는 전기화학반응조; 상기 전기화학반응조에서 배출된 지하수를 수용하며, 산소가 공급되어 상기 지하수에 포함되어 있는 철을 수산화물 형태로 침전시키며, 상기 수산화물 형태의 철은 지하수 내 중금속과 흡착 및 공침되는 폭기조; 및 상기 폭기조에서 배출된 지하수와 침전물을 상호 분리하기 위한 여과조;를 구비하는 것에 특징이 있다. Complex contaminated groundwater treatment system according to the present invention for achieving the above object, including a reaction vessel for receiving ground water, and the negative electrode and iron material positive electrode installed in the reaction tank and a power supply for applying electricity to the positive electrode and negative electrode, An electrochemical reaction tank in which the iron is oxidized and eluted, the dissolved oxygen in ground water oxidizes divalent iron to trivalent iron and an anaerobic environment is formed; An aeration tank accommodating the groundwater discharged from the electrochemical reactor and supplying oxygen to precipitate iron contained in the groundwater in hydroxide form, wherein the hydroxide form iron is adsorbed and co-precipitated with heavy metals in the groundwater; And a filtration tank for separating the groundwater discharged from the aeration tank and the sediment with each other.
본 발명에서는 전기화학반응을 통해 비소를 제거하기 위한 물질인 철을 용출시키며, 이와 함께 용존산소가 제거되어 혐기성 환경이 형성되는 것을 이용하여 미생물을 제거하는 공정을 도입하였다. In the present invention, a process for removing microorganisms by using an electrochemical reaction to elute iron, which is a substance for removing arsenic, and dissolved oxygen is removed to form an anaerobic environment.
본 발명에 따르면 중금속과 미생물에 의하여 복합 오염되어 있는 지하수를 음용 가능한 수준으로 정화처리할 수 있다는 이점이 있다. According to the present invention, there is an advantage that the groundwater complex contaminated by heavy metals and microorganisms can be purified to a drinking level.
특히 고체 상태의 철을 그대로 사용하지 않고 용출시키는 과정을 거침으로써 철의 비표면적이 증대하여 비소를 흡착 및 공침시키는데 매우 큰 이점이 있다. In particular, the specific surface area of iron is increased by elution without using solid iron as it is, which has a great advantage in adsorbing and co-precipitation of arsenic.
또한 전기화학반응을 이용하면서 단지 비소만을 제거하는 것이 아니라, 혐기성 환경이 조성되는 것을 이용함으로써 한 번의 공정으로 미생물 제거라는 효과도 나타낼 수 있으므로 공정의 혁신 및 간소화가 가능하다는 이점이 있다. In addition, the use of electrochemical reactions not only removes arsenic, but also by using an anaerobic environment that can produce microbial removal in one process.
이를 통해 상수 시설 등의 인프라가 충분하지 않은 지역에서 지하수를 깨끗하게 처리하여 음용수로 활용할 수 있는 계기를 마련할 것으로 보인다. Through this, the groundwater will be cleaned and used as drinking water in areas with insufficient infrastructure such as water supply facilities.
한편, 여기에서 명시적으로 언급되지 않은 효과라 하더라도, 본 발명의 기술적 특징에 의해 기대되는 이하의 명세서에서 기재된 효과 및 그 잠정적인 효과는 본 발명의 명세서에 기재된 것과 같이 취급됨을 첨언한다.On the other hand, even if the effects are not explicitly mentioned herein, the effects described in the following specification expected by the technical features of the present invention and its provisional effects are treated as described in the specification of the present invention.
도 1 및 도 2는 pH 조건에 따른 각 비소종의 비율을 나타낸 표로서, 도 1은 3가 비소종에 대한 표이며, 도 2는 5가 비소종에 대한 표이다. 1 and 2 is a table showing the ratio of each arsenic species according to the pH conditions, Figure 1 is a table for trivalent arsenic species, Figure 2 is a table for pentavalent arsenic species.
도 3은 본 발명의 일 실시예에 따른 복합 오염 지하수 처리방법의 개략적 흐름도이다. 3 is a schematic flowchart of a method for treating complex contaminated groundwater according to an embodiment of the present invention.
도 4는 본 발명의 일 실시예에 따른 복합 오염 지하수 처리시스템의 개략적 모식도이다. Figure 4 is a schematic diagram of a complex contaminated groundwater treatment system according to an embodiment of the present invention.
도 5 및 도 6은 본 발명을 실험한 결과로서, 전류밀도에 따른 지하수 내 미생물 오염개체수 변화(도 5) 및 지하수 수질변화(도 6)를 나타난 그래프이다. 5 and 6 are graphs showing changes in the number of microbial contaminants in groundwater (FIG. 5) and groundwater quality (FIG. 6) according to current densities as a result of experimenting with the present invention.
도 7 내지 도 9는 본 발명을 실험한 결과로서, 폭기조건과 비폭기조건에서 반응시간에 따른 지하수 내 산소량의 변화(도 7), 산화환원전위의 변화(도 8) 및 미생물 제거율(도 9)를 나타낸 것이다. 7 to 9 are the results of experiments of the present invention, the change in the amount of oxygen in the groundwater according to the reaction time in the aeration and non-aeration conditions (Fig. 7), the change in the redox potential (Fig. 8) and the microbial removal rate (Fig. 9 ).
도 10 내지 도 12는 전류밀도를 상승시켜서 앞의 도 7 내지 도 9와 같은 실험을 수행한 결과이다. 10 to 12 show the results of performing the same experiment as in FIGS. 7 to 9 by increasing the current density.
도 13 및 도 14는 본 발명을 실험한 결과로서 시간에 따른 지하수 내 비소 제거율(도 13)과 탁도의 변화(도 14)를 나타낸 것이다. 13 and 14 show the arsenic removal rate (FIG. 13) and turbidity change (FIG. 14) in groundwater with time as a result of experimenting with the present invention.
도 15 및 도 16은 원수 유입량을 증대시켜 도 13 내지 도 14와 동일한 실험을 수행한 결과이다. 15 and 16 show the result of performing the same experiment as in FIGS. 13 to 14 by increasing the raw water inflow.
※ 첨부된 도면은 본 발명의 기술사상에 대한 이해를 위하여 참조로서 예시된 것임을 밝히며, 그것에 의해 본 발명의 권리범위가 제한되지는 아니한다.The accompanying drawings show that they are illustrated as a reference for understanding the technical idea of the present invention, by which the scope of the present invention is not limited.
상기 목적을 달성하기 위한 본 발명에 따른 복합 오염 지하수 처리시스템은,지하수를 수용하는 반응조와, 상기 반응조에 설치되는 음전극과 철 소재의 양전극 및 상기 양전극과 음전극에 전기를 인가하는 전원부를 포함하여, 상기 양전극에서는 철이 산화되어 용출되며, 지하수 내 용존산소가 2가 철을 3가 철로 산화시키며 혐기성 환경이 조성되는 전기화학반응조; 상기 전기화학반응조에서 배출된 지하수를 수용하며, 산소가 공급되어 상기 지하수에 포함되어 있는 철을 수산화물 형태로 침전시키며, 상기 수산화물 형태의 철은 지하수 내 중금속과 흡착 및 공침되는 폭기조; 및 상기 폭기조에서 배출된 지하수와 침전물을 상호 분리하기 위한 여과조;를 구비하는 것에 특징이 있다. Complex contaminated groundwater treatment system according to the present invention for achieving the above object, including a reaction vessel for receiving ground water, and the negative electrode and iron material positive electrode installed in the reaction tank and a power supply for applying electricity to the positive electrode and negative electrode, An electrochemical reaction tank in which the iron is oxidized and eluted, the dissolved oxygen in ground water oxidizes divalent iron to trivalent iron and an anaerobic environment is formed; An aeration tank accommodating the groundwater discharged from the electrochemical reactor and supplying oxygen to precipitate iron contained in the groundwater in hydroxide form, wherein the hydroxide form iron is adsorbed and co-precipitated with heavy metals in the groundwater; And a filtration tank for separating the groundwater discharged from the aeration tank and the sediment with each other.
본 발명에 따르면, 상기 중금속은 특히 비소를 포함하며, 상기 미생물은 대장균을 포함한 호기성 세균이다. According to the invention, the heavy metal comprises especially arsenic and the microorganism is an aerobic bacterium including Escherichia coli.
본 발명의 일 실시예에서, 상기 양전극과 음전극은 모두 철 소재를 사용하는 것이 바람직하다. In one embodiment of the present invention, it is preferable that both the positive electrode and the negative electrode use an iron material.
또한, 상기 여과조는 상향식 흐름을 형성하도록 유입구는 하부에 유출구는 상부에 형성되며, 상기 유입구와 유출구 사이에 침전물을 걸러내기 위한 필터가 개재되는 것이 바람직하다.In addition, the inlet is formed at the bottom of the inlet is formed in the upper portion so as to form a bottom-up flow, it is preferred that a filter for filtering the sediment between the inlet and the outlet.
한편, 본 발명에 따른 중금속 및 미생물로 복합 오염된 지하수를 처리하기 위한 방법은, (a)상기 지하수에 철 소재의 양전극과 음전극을 투입하여 전기화학반응을 수행하여, 지하수 내로 철이 용출되도록 하며, 지하수 내 용존산소가 철과 반응하여 혐기성 환경을 조성하여 미생물을 제거하는 단계; (b)상기 지하수에 산소를 공급하여 용존된 철이 수산화물 형태로 침전시키며, 철이 침전되는 과정에서 상기 지하수 내 중금속을 수산화물 형태의 철에 흡착 및 공침시켜 제거하는 단계; 및 (c)상기 지하수 내 침전물과 상등수를 상호 분리하는 단계;를 구비하는 것에 특징이 있다. On the other hand, the method for treating the groundwater complex contaminated with heavy metals and microorganisms according to the present invention, (a) by putting a positive electrode and a negative electrode of the iron material in the groundwater to perform an electrochemical reaction, so that iron is eluted into the groundwater, Dissolved oxygen in the ground water reacts with iron to create an anaerobic environment to remove microorganisms; (b) supplying oxygen to the ground water to precipitate dissolved iron in hydroxide form, and removing heavy metals in the ground water by adsorbing and co-precipitation to iron in hydroxide form during the precipitation of iron; And (c) separating the sediment and the supernatant from each other in the groundwater.
본 발명을 설명함에 있어서 관련된 공지기능에 대하여 이 분야의 기술자에게 자명한 사항으로서 본 발명의 요지를 불필요하게 흐릴 수 있다고 판단되는 경우에는 상세한 설명을 생략한다. In the following description of the present invention, when it is determined that the subject matter of the present invention may be unnecessarily obscured by the person skilled in the art with respect to the related well-known functions, the detailed description will be omitted.
본 발명은 비소 및 미생물에 의해 복합 오염되어 있는 지하수를 정화처리하기 위한 방법 및 시스템에 관한 것이다. 다만, 본 발명에서 제거하고자 하는 오염물질은 비소에 한정되는 것은 아니며, 비소와 유사한 물리적 및/또는 화학적 거동을 따르는 다른 중금속으로 확장될 수 있을 것이다. 또한 본 발명에서 처리하고자 하는 주요 대상은 지하수이지만, 반드시 지하수에 한정되는 것은 아니며 중금속과 세균으로 복합 오염된 다양한 형태의 수자원이 포함될 수 있음을 미리 밝혀둔다. The present invention relates to a method and system for purifying groundwater complex contaminated with arsenic and microorganisms. However, the contaminant to be removed in the present invention is not limited to arsenic, but may be expanded to other heavy metals having similar physical and / or chemical behaviors to arsenic. In addition, the main subject to be treated in the present invention is groundwater, but is not necessarily limited to groundwater, it is revealed in advance that it can include various types of water resources contaminated with heavy metals and bacteria.
이하, 본 발명의 바람직한 실시예에 따른 중금속 및 미생물 복합 오염 지하수 처리방법 및 처리시스템에 대하여 더욱 상세히 설명하기로 한다. Hereinafter, a heavy metal and microbial complex contaminated groundwater treatment method and treatment system according to a preferred embodiment of the present invention will be described in more detail.
도 3은 본 발명의 일 실시예에 따른 복합 오염 지하수 처리방법의 개략적 흐름도이며, 도 4는 본 발명의 일 실시예에 따른 복합 오염 지하수 처리시스템의 개략적 모식도이다. 3 is a schematic flowchart of a complex contaminated groundwater treatment method according to an embodiment of the present invention, Figure 4 is a schematic diagram of a complex contaminated groundwater treatment system according to an embodiment of the present invention.
본 발명의 일 실시예에 따른 복합 오염 지하수 처리방법은 비소를 제거하는 과정과, 지하수 내 혐기성 환경을 조성하여 미생물을 제거하는 과정이 함께 이루어져야 한다. 또한 위 2개의 과정을 간단한 공정으로 수행해야 한다는 과제가 있다. 이를 위하여 본 발명에서는 전기화학반응을 도입하여 비소를 제거하며, 동시에 혐기성 환경을 조성함으로써 미생물을 제거하는 공정을 개발하였다. Complex contaminated groundwater treatment method according to an embodiment of the present invention should be carried out with the process of removing arsenic, the process of removing microorganisms by creating an anaerobic environment in the groundwater. In addition, there is a problem that the above two processes must be performed in a simple process. To this end, in the present invention, an electrochemical reaction was introduced to remove arsenic, and at the same time, an anaerobic environment was developed to remove microorganisms.
도 3 및 도 4를 참고하면, 본 발명에 따른 처리방법은 크게 3가지 단계로 이루어지며 이를 위하여 시스템이 제공된다. Referring to Figures 3 and 4, the treatment method according to the present invention is largely made of three steps for this purpose is provided with a system.
첫 번째 단계는 전기화학반응을 통하여 비소를 제거하기 위한 물질로서 철을 용출해 냄과 동시에 지하수로부터 용존 산소를 제거하여 지하수를 혐기성 환경으로 조성한다. 첫 번째 단계는 본 발명에 따른 복합 오염 지하수 처리시스템(100)의 전기화학반응조(10)에 의해 구현된다. The first step is to remove arsenic as a substance to remove arsenic through electrochemical reactions and to remove dissolved oxygen from groundwater to form groundwater into an anaerobic environment. The first step is implemented by the electrochemical reactor 10 of the complex contaminated groundwater treatment system 100 according to the present invention.
전기화학반응조(10)는 지하수를 수용하기 위한 반응조로서, 그 내부에는 양전극(11)과 음전극(12)이 서로 이격되게 설치된다. 그리고 양전극(11)과 음전극(12)은 전원부(13)에 전기적으로 연결된다. 본 실시예에서 양전극(11)으로는 철 전극이 사용되며, 음전극(12)으로도 철 전극이 사용된다. 다만, 음전극은 철 이외의 다른 소재의 전극으로 사용하여도 무방하다. The electrochemical reaction vessel 10 is a reaction vessel for accommodating groundwater, and the positive electrode 11 and the negative electrode 12 are installed in the spaced apart from each other. The positive electrode 11 and the negative electrode 12 are electrically connected to the power supply unit 13. In this embodiment, an iron electrode is used as the positive electrode 11, and an iron electrode is also used as the negative electrode 12. However, the negative electrode may be used as an electrode of a material other than iron.
전류가 인가되면 양전극(11)에서는 아래의 반응식1,2와 같이 고체 상태의 철이 산화되어 지하수로 용출되면서 전자가 발생된다. 전자는 음전극(12) 주변에서 반응식3과 같이 수소 이온을 환원시켜 기체로 전환시킨다. 산화반응은 반응식1과 같은 형태가 주류를 이루어, 지하수 내 용존된 철은 주로 2가를 띠게 된다. When a current is applied, the positive electrode 11 is oxidized in the positive electrode 11 and eluted into groundwater as shown in Equations 1 and 2 below to generate electrons. The electrons are converted to gas by reducing hydrogen ions around the negative electrode 12 as in Scheme 3. Oxidation reaction is mainly in the form as shown in Scheme 1, so that the dissolved iron in the groundwater is mainly divalent.
Fe(s) = Fe2+ + 2e- (-0.44V) ... 반응식1(양전극)Fe (s) = Fe 2+ + 2e - ( - 0.44V) ... Scheme 1 (positive electrode)
Fe(s) = Fe3+ + 3e- (-0.04V) ... 반응식2(양전극)Fe (s) = Fe 3+ + 3e - ( - 0.04V) ... Scheme 2 (positive electrode)
H+ + e- = 0.5H2(g) (0.00V) ... 반응식3(음전극) H + + e - = 0.5H 2 (g) (0.00V) ... scheme 3 (the cathode electrode)
상기한 반응이 일어난 후, 2가 철은 아래의 반응식4~6과 같이 수산화물 형태로 전환되어 고체 상태로 침전하게 된다. After the above reaction, the divalent iron is converted to the hydroxide form as shown in Schemes 4-6 below to precipitate in a solid state.
4Fe2+ + O2(g) + 2H2O = 4Fe3+ + 4OH- ... 반응식4 4Fe 2+ + O 2 (g) + 2H 2 O = 4Fe 3+ + 4OH - ... scheme 4
Fe3+ + 3OH- = Fe(OH)3 ... 반응식5 Fe 3+ + 3OH - = Fe ( OH) 3 ... scheme 5
Fe(OH)3 = FeO(OH)(s) + H2O ... 반응식6 Fe (OH) 3 = FeO (OH) (s) + H 2 O ...
즉, 철은 FeO(OH) 형태로 괴타이트(goethite) 또는 레피도크로사이트(lepidocrocite)로 침전된다. 여기서 비소를 제거하기 위한 물질로서 철이 침전되었다는 점보다 더욱 중요하게 생각해야 할 부분은, 철이 용출 후에 다시 침전되었다는 점이다. 철은 오염물질의 흡착물질로서 많이 사용되고 있으며, 주로 고체 상태로 제조된 것, 예컨대 아이언볼이나 파우더를 사용한다. 그러나 본 발명과 같이 철을 용출시킨 후 수산화물 형태로 침전시키면 비표면적이 매우 넓어진다는 점이다. 비표면적이 넓어진다는 것은 비소가 흡착될 수 있는 면적 또는 비소가 철과 결합하여 공침될 수 있는 공간이 획기적으로 커진다는 것을 의미한다. 기존에 고체 상태의 철을 흡착제로 사용하는 것과는 비소 제거율에서 수십배 이상의 차이를 보일 것으로 기대한다. That is, iron is precipitated as goethite or lepidocrocite in the form of FeO (OH). The more important point here than iron precipitated as a material for removing arsenic is that iron precipitated again after elution. Iron is widely used as an adsorbent of contaminants, and mainly used in the solid state, for example, iron balls or powder. However, when the iron is eluted as in the present invention and precipitated in hydroxide form, the specific surface area becomes very wide. The increased specific surface area means that the area where arsenic can be adsorbed or the space where arsenic can be co-precipitated in combination with iron is significantly increased. It is expected that there will be more than a few orders of magnitude difference in the removal of arsenic from the use of solid iron as an adsorbent.
또한 주목해야 할 점은 반응식4와 같이 지하수 내 용존 산소가 소모된다는 점이다. 더불어서 산화환원전위(ORP)가 급격하게 저하된다. 즉, 산소가 소모되고 ORP가 감소된다는 것은 전기화학반응조 내의 지하수가 혐기성 환경으로 조성된다는 것이며, 지하수 내 호기성 세균들은 혐기성 환경에서 활성을 잃고 제거된다. 본 발명에서는 비소를 제거하기 위한 물질로서 철을 용출시키는 과정에서, 산소가 소모되어 혐기성 환경이 조성된다는 점을 발견하였으며, 혐기성 환경하에서 대장균 등의 세균들이 사멸하는 것을 확인하였다. 본 발명에서 제거하고자 하는 미생물은 분원성대장균, 총대장균군 등을 포함하여 호기성 세균이 많으므로 논리적으로 타당성이 있다. 실험 결과에 대해서는 후술하기로 한다. It should also be noted that dissolved oxygen in groundwater is consumed as in Scheme 4. In addition, the redox potential (ORP) is drastically lowered. In other words, oxygen consumption and ORP decrease means that the groundwater in the electrochemical reactor is made into the anaerobic environment, and the aerobic bacteria in the groundwater are lost and removed in the anaerobic environment. In the present invention, in the process of eluting iron as a material for removing arsenic, it was found that oxygen is consumed to form an anaerobic environment, and it was confirmed that bacteria such as E. coli are killed under an anaerobic environment. The microorganism to be removed in the present invention is logically valid because there are many aerobic bacteria, including fecal coliform, total coliform group and the like. The experimental results will be described later.
상기한 바와 같이, 전기화학반응조(10)를 이용하여 철을 수산화물 형태로 침전시키고, 지하수 내 미생물을 제거한 후에는 본격적으로 비소를 제거하기 위한 공정을 수행한다. As described above, iron is precipitated in the form of hydroxide using the electrochemical reaction tank 10, and after removing microorganisms in the groundwater, a process for removing arsenic is performed in earnest.
두 번째 공정은 지하수 내 비소를 철 수산화물에 흡착시키거나 또는 철 수산화물과 함께 공침시켜 제거하는 과정이다. 이러한 공정은 폭기조(20)에서 이루어진다. 전기화학반응조(10)에 수용된 지하수와 일부 침전물은 모두 폭기조(20)로 이송한다. 그리고 폭기조(20)에 산소를 공급한다. The second process is the removal of arsenic in groundwater by iron hydroxide or coprecipitation with iron hydroxide. This process is performed in the aeration tank 20. Groundwater and some sediment contained in the electrochemical reaction tank 10 are all transferred to the aeration tank 20. Then, oxygen is supplied to the aeration tank 20.
하기의 반응식7~반응식9에는 비소가 철 수산화물과 공침되는 반응(반응식7,8)과, 흡착되는 반응(반응식9)이 나타나 있다. Reactions 7 to 9 below show reactions in which arsenic co-precipitates with iron hydroxides (Scheme 7, 8) and adsorbed reaction (Scheme 9).
2FeO(OH)(s) + H2AsO4 - = (FeO)2HAsO4 - + H2O + OH- ... 반응식7 2FeO (OH) (s) + H 2 AsO 4 - = (FeO) 2 HAsO 4 - + H 2 O + OH - ... Scheme 7
3FeO(OH)(s) + HAsO4 2- = (FeO)3AsO4(s) - + H2O + 2OH- ... 반응식8 3FeO (OH) (s) + HAsO 4 2- = (FeO) 3 AsO 4 (s) - + H 2 O + 2OH - ... Scheme 8
FeO(OH)3(s) + AsO4 3- = (Fe(OH)3AsO4 3-)(s) ... 반응식9FeO (OH) 3 (s) + AsO 4 3- = (Fe (OH) 3 AsO 4 3- ) (s) ... Scheme 9
위 반응식7 내지 반응식9를 참고하면, 수산화물 형태의 철이 비소와 흡착 및 공침하여 고체 상태로 침전하는 것을 알 수 있다. 비소를 제거하기 위해서는 철이 수산화물 형태로 침전되는 것이 먼저 선행되어야 하며, 침전되는 철 수산화물이 많을수록 비소가 함께 공침하거나 흡착되는 양이 많으므로, 비소 제거율은 철 수산화물의 침전량에 의존하게 된다. Referring to the reaction schemes 7 to 9, it can be seen that the hydroxide form iron precipitates in the solid state by adsorption and co-precipitation with arsenic. In order to remove arsenic, iron should first be precipitated in the form of a hydroxide. Since the more iron hydroxide precipitated, the more arsenic co- precipitates or adsorbs together, the arsenic removal rate depends on the amount of iron hydroxide precipitated.
앞의 반응식4를 참고하면, 철이 수산화물로 침전되기 위한 중요 조건 중 하나는 산소의 존재이다. 철 전극으로부터 용출된 2가 철은 산소와 만나 3가 철로 변환되면서 수산화물로 침전되기 때문이다. 그렇다면 앞의 전기화학반응조에 공기를 공급함으로써 철의 침전을 가속화시킬 수 있다. 그러나 산소를 공급한다는 것은 미생물의 제거와 관련하여 호기성 환경을 형성하는 것이 되므로 바람직하지 않다. 이에 본 발명에서는 전기화학반응조(10)에서는 지하수 내 용존 산소에 의하여 2가 철을 산화시키고, 미생물 제거에 중점을 둔다. 혐기성 조건이 형성되어 미생물이 모두 제거된 상태에서는 이제 폭기조(20)에서 산소를 공급하여 철의 침전을 가속화시키며 이 과정에서 비소를 제거하는 것이다. Referring to Scheme 4 above, one of the important conditions for iron to precipitate into hydroxide is the presence of oxygen. This is because divalent iron eluted from the iron electrode meets with oxygen and is converted into trivalent iron and precipitates as a hydroxide. Then, by supplying air to the previous electrochemical reactor, the precipitation of iron can be accelerated. However, supplying oxygen is undesirable since it creates an aerobic environment with respect to the removal of microorganisms. In the present invention, the electrochemical reactor 10 oxidizes the divalent iron by dissolved oxygen in the groundwater and focuses on the removal of microorganisms. When anaerobic conditions are formed and all microorganisms are removed, oxygen is now supplied from the aeration tank 20 to accelerate the precipitation of iron and remove arsenic in the process.
이제 비소를 포함하는 침전물과, 액체 상태의 지하수를 상호 분리하는 세 번째 공정이 남는다. 세 번째 공정은 여과조(30)에서 수행한다. 액체 상태의 지하수와 고체 상태의 침전물을 상호 분리하는 기술은 다양하지만, 본 실시예에서는 상향식 여과조를 사용한다. 즉, 폭기조(20)에서 지하수와 침전물이 함께 여과조(30)로 이송되는데, 지하수와 침전물은 여과조(30)의 하부에 형성된 유입구(31)를 통해 유입되어 여과조(30)의 상부에 마련된 유출구(32)를 통해 배출된다. 그리고 여과조(30)의 중간에는 필터(33)가 마련된다. 비소를 포함하고 있는 고체 상태의 침전물은 이 필터(33)를 통과하지 못하고, 비소가 제거된 액체 상태의 지하수만 필터(33)를 통과할 수 있다. 또한 상향식 흐름을 형성하기 때문에 고체 침전물은 자중에 의하여 하향 힘을 받으므로 이송이 제한된다. 침전물들이 서로 응집시켜 자중을 늘리도록 응집제 등을 선택적으로 투입할 수도 있다. There is now a third process of separating sediment containing arsenic and liquid groundwater from each other. The third process is carried out in the filtration tank (30). Although techniques for separating the groundwater in the liquid state and the precipitate in the solid state vary, the present embodiment uses a bottom-up filtration tank. That is, in the aeration tank 20, the ground water and the sediment are transferred together to the filtration tank 30, and the ground water and the sediment are introduced through the inlet 31 formed in the lower portion of the filtration tank 30, and the outlet port provided in the upper portion of the filtration tank 30 ( Through 32). And the filter 33 is provided in the middle of the filtration tank 30. Solid precipitate containing arsenic does not pass through the filter 33, and only groundwater in the liquid state from which arsenic has been removed may pass through the filter 33. In addition, because of the formation of the bottom-up flow, the solid precipitate is forced downward by its own weight, so transport is limited. A flocculant or the like may be selectively added to cause the precipitates to agglomerate with each other to increase their own weight.
상기한 과정을 거쳐 지하수에서는 비소와 미생물이 모두 제거될 수 있으며, 지하수는 정화처리가 완료되어 테스트를 통해 식수로 음용가능할 것으로 기대된다. Through the above process, both arsenic and microorganisms can be removed from the groundwater, and the groundwater is expected to be drinkable as drinking water after the purification process is completed.
이하에서는 본 발명에 따른 중금속 및 지하수 복합 오염 지하수 처리방법과 처리시스템에 대한 실험예를 설명하기로 한다. Hereinafter will be described an experimental example for the heavy metal and groundwater complex contaminated groundwater treatment method and treatment system according to the present invention.
실험에 사용된 시료는 베트남에서 채취한 것으로서 비소를 포함한 중금속과 대장균 등의 세균으로 복합오염된 것이었다. 전기화학반응조를 설치하고 전류밀도에 따른 지하수 시료의 수질을 조사하였으며, 그 결과가 도 5 및 도 6의 그래프에 나타나 있다. 도 5 및 도 6의 실험은 시료 370ml에 대해서 10분 동안 전기화학반응을 시킨 결과이다. The sample used in the experiment was taken in Vietnam and was contaminated with bacteria such as heavy metals containing arsenic and E. coli. An electrochemical reactor was installed and the water quality of the groundwater sample was investigated according to the current density, and the results are shown in the graphs of FIGS. 5 and 6. 5 and 6 are the results of the electrochemical reaction for 10 minutes on the sample 370ml.
도 5 및 도 6의 결과를 살펴보면, 전류밀도가 증가함에 따라 총대장균(total coliforms), 대장균(E.coli) 및 호기성 박테리아(aerobic bacteria)는 점차 감소하며, 대략 1.145mA/cm2 수준에서 거의 대부분의 미생물이 사멸되는 것을 확인하였다. 동시에 지하수의 수질을 측정한 도 6을 참고하면, pH는 일정하게 유지되는 반면, 산화환원전위(ORP)와 산소량(DO)는 현저히 감소됨을 알 수 있다. 즉, 산소가 소모되고 산화환원전위가 낮아지면서 지하수 내 혐기성 조건이 형성되고, 이에 따라 미생물이 사멸하고 있는 것으로 추정할 수 있다. Referring to the results of FIGS. 5 and 6, as the current density increases, total coliforms, E. coli, and aerobic bacteria gradually decrease, and at approximately 1.145 mA / cm 2 level. It was confirmed that most of the microorganisms were killed. At the same time, referring to Figure 6, which measures the water quality of the groundwater, it can be seen that while the pH is kept constant, the redox potential (ORP) and oxygen amount (DO) is significantly reduced. In other words, as oxygen is consumed and the redox potential is lowered, anaerobic conditions in groundwater are formed, and thus, microorganisms may be killed.
도 7 내지 도 9는 전류밀도를 대략 0.114mA/cm2으로 고정하고 반응시간에 따른 수질특성 및 미생물 제거효율을 실험한 것으로서, 별도를 산소를 공급하지 않는 조건(실선)과 폭기조건(점선)으로 나누어 실험한 것이다. 7 to 9 are experiments of water quality characteristics and microbial removal efficiency according to the reaction time by fixing the current density at approximately 0.114 mA / cm 2 , and do not supply oxygen separately (solid line) and aeration condition (dotted line). The experiment was divided by.
도 7 내지 도 9의 결과를 살펴보면, 폭기를 수행하지 않은 경우의 결과는 앞의 도 5 및 도 6의 결과와 유사하지만, 폭기를 수행하게 되면 미생물 제거율이 현저히 저하되는 것을 확인하였다. 마찬가지로 산화환원전위와 산소량도 폭기조건과 그렇지 않은 경우에 있어서 극명한 대비를 보인다. Referring to the results of FIGS. 7 to 9, the results when the aeration was not performed were similar to the results of FIGS. 5 and 6, but when the aeration was performed, the microbial removal rate was significantly reduced. Similarly, the redox potential and the amount of oxygen show a sharp contrast in aeration conditions and in other cases.
도 10 내지 도 12에서는 전류밀도를 0.343mA/cm2으로 고정한 결과이다. 도 10 내지 도 12에서도 도 7 내지 도 9에서와 동일한 결과를 확인할 수 있었다. 10 to 12 show the result of fixing the current density at 0.343 mA / cm 2 . 10 to 12, the same results as in FIGS. 7 to 9 were confirmed.
실험 내용을 정리하면, 폭기를 수행하지 않은 경우 전기화학반응조 내 용존 산소가 제거되고 산화환원전위가 낮아지면서 혐기성 조건이 형성됨을 확인하였다. 그리고 혐기성 조건에서 미생물이 제거되는 것도 확인하였다. In summary, when the aeration was not performed, it was confirmed that anaerobic conditions were formed by removing dissolved oxygen and lowering the redox potential in the electrochemical reactor. It was also confirmed that the microorganisms were removed under anaerobic conditions.
위와 같이 미생물 제거를 확인한 후에 본 발명에 따라 전기화학반응조, 폭기조 및 여과조를 활용하여 비소제거와 미생물 제거 효과에 대해서 실험하였다. 실험 조건은 원수 유입량을 0.5ton/day로 하였다. After confirming the removal of the microorganisms as described above, using the electrochemical reaction tank, aeration tank and filtration tank according to the present invention was tested for the effect of arsenic removal and microbial removal. Experimental conditions were the raw water inflow was 0.5ton / day.
먼저 도 13에는 비소제거율과 탁도에 대한 결과가 나타나 있다. 도 13을 참고하면, 초기 비소농도가 376μg/L에서 10분이 경과한 시험에서 음용수 기준인 10μg/L 이하로 저하되는 것을 확인하였으며, 지하수의 탁도 역시 현저히 저하되는 것을 확인하였다. 도 14를 참고하면, 대장균과 호기성 미세물도 반응시간이 100분을 경과하는 시점에서 거의 완전히 제거됨을 알 수 있다.First, results of arsenic removal rate and turbidity are shown in FIG. 13. Referring to FIG. 13, it was confirmed that the initial arsenic concentration was lowered below 10 μg / L of drinking water in the test after 10 minutes at 376 μg / L, and the turbidity of the groundwater was also significantly reduced. Referring to FIG. 14, it can be seen that E. coli and aerobic fines are almost completely removed when the reaction time passes 100 minutes.
도 14 및 도 15의 실험결과는 앞의 실험을 반복하되, 원수 유입량을 1.1ton/day로 증가시킨 것이다. 도 14 및 도 15의 결과도 앞의 비소제거율, 탁도저감율 및 미생물 제거율과 동일한 결과를 확인할 수 있었다. Experimental results of FIGS. 14 and 15 are repeated the previous experiment, but increased the raw water inflow to 1.1ton / day. 14 and 15 also confirmed the same results as the previous arsenic removal rate, turbidity reduction rate and microbial removal rate.
이상에서 설명한 바와 같이, 본 발명에서는 전기화학반응을 통해 비소를 제거하기 위한 물질인 철을 용출시키며, 이와 함께 용존산소가 제거되어 혐기성 환경이 형성되는 것을 이용하여 미생물을 제거하는 공정을 도입하였다. As described above, in the present invention, a process for removing microorganisms by eluting iron, which is a substance for removing arsenic through an electrochemical reaction, and removing dissolved oxygen to form an anaerobic environment is introduced.
본 발명에 따르면 중금속과 미생물에 의하여 복합 오염되어 있는 지하수를 음용 가능한 수준으로 정화처리할 수 있다는 이점이 있다. According to the present invention, there is an advantage that the groundwater complex contaminated by heavy metals and microorganisms can be purified to a drinking level.
특히 고체 상태의 철을 그대로 사용하지 않고 용출시키는 과정을 거침으로써 철의 비표면적이 증대하여 비소를 흡착 및 공침시키는데 매우 큰 이점이 있다. In particular, the specific surface area of iron is increased by elution without using solid iron as it is, which has a great advantage in adsorbing and co-precipitation of arsenic.
또한 전기화학반응을 이용하면서 단지 비소만을 제거하는 것이 아니라, 혐기성 환경이 조성되는 것을 이용함으로써 한 번의 공정으로 미생물 제거라는 효과도 나타낼 수 있으므로 공정의 혁신 및 간소화가 가능하다는 이점이 있다. In addition, the use of electrochemical reactions not only removes arsenic, but also by using an anaerobic environment that can produce microbial removal in one process.
이를 통해 상수 시설 등의 인프라가 충분하지 않은 지역에서 지하수를 깨끗하게 처리하여 음용수로 활용할 수 있는 계기를 마련할 것으로 보인다. Through this, the groundwater will be cleaned and used as drinking water in areas with insufficient infrastructure such as water supply facilities.
본 발명의 보호범위가 이상에서 명시적으로 설명한 실시예의 기재와 표현에 제한되는 것은 아니다. 또한, 본 발명이 속하는 기술분야에서 자명한 변경이나 치환으로 말미암아 본 발명이 보호범위가 제한될 수도 없음을 다시 한 번 첨언한다.The protection scope of the present invention is not limited to the description and expression of the embodiments explicitly described above. In addition, it is again noted that the scope of protection of the present invention may not be limited due to obvious changes or substitutions in the technical field to which the present invention pertains.

Claims (7)

  1. 지하수를 수용하는 반응조와, 상기 반응조에 설치되는 음전극과 철 소재의 양전극 및 상기 양전극과 음전극에 전기를 인가하는 전원부를 포함하여, 상기 양전극에서는 철이 산화되어 용출되며, 지하수 내 용존산소가 2가 철을 3가 철로 산화시키며 혐기성 환경이 조성되는 전기화학반응조;Including a reactor for accommodating ground water, a positive electrode of the negative electrode and iron material installed in the reactor and a power supply for applying electricity to the positive electrode and the negative electrode, the iron is oxidized and eluted in the positive electrode, dissolved oxygen in the ground water divalent iron An electrochemical reactor that oxidizes trivalent iron to create an anaerobic environment;
    상기 전기화학반응조에서 배출된 지하수를 수용하며, 산소가 공급되어 상기 지하수에 포함되어 있는 철을 수산화물 형태로 침전시키며, 상기 수산화물 형태의 철은 지하수 내 중금속과 흡착 및 공침되는 폭기조; 및 An aeration tank accommodating the groundwater discharged from the electrochemical reactor and supplying oxygen to precipitate iron contained in the groundwater in hydroxide form, wherein the hydroxide form iron is adsorbed and co-precipitated with heavy metals in the groundwater; And
    상기 폭기조에서 배출된 지하수와 침전물을 상호 분리하기 위한 여과조;를 구비하는 것을 특징으로 하는 중금속 및 미생물 복합 오염 지하수 처리시스템. And a filtering tank for separating the groundwater discharged from the aeration tank and the sediment with each other.
  2. 제1항에 있어서,The method of claim 1,
    상기 중금속은 비소를 포함하는 것을 특징으로 하는 중금속 및 미생물 복합 오염 지하수 처리시스템. The heavy metal and microbial complex contamination groundwater treatment system, characterized in that it comprises arsenic.
  3. 제1항에 있어서, The method of claim 1,
    상기 미생물은 호기성 세균인 것을 특징으로 하는 중금속 및 미생물 복합 오염 지하수 처리시스템. The microorganism is aerobic bacteria, heavy metal and microbial complex contamination groundwater treatment system, characterized in that.
  4. 제1항에 있어서, The method of claim 1,
    상기 음전극도 철 소재인 것을 특징으로 하는 중금속 및 미생물 복합 오염 지하수 처리시스템. Heavy metal and microbial complex contamination groundwater treatment system, characterized in that the negative electrode is also iron material.
  5. 제1항에 있어서,The method of claim 1,
    상기 여과조는 상향식 흐름을 형성하도록 유입구는 하부에 유출구는 상부에 형성되며, 상기 유입구와 유출구 사이에 침전물을 걸러내기 위한 필터가 개재되는 것을 특징으로 하는 중금속 및 미생물 복합 오염 지하수 처리시스템. The filter tank is formed in the bottom of the inlet to the bottom to form a flow upward, the heavy metal and microbial complex contaminated groundwater treatment system, characterized in that a filter for filtering the precipitate is interposed between the inlet and the outlet.
  6. 중금속 및 미생물로 복합 오염된 지하수를 처리하기 위한 방법으로서, A method for treating groundwater complex contaminated with heavy metals and microorganisms,
    (a)상기 지하수에 철 소재의 양전극과 음전극을 투입하여 전기화학반응을 수행하여, 지하수 내로 철이 용출되도록 하며, 지하수 내 용존산소가 철과 반응하여 혐기성 환경을 조성하여 미생물을 제거하는 단계; (a) inserting the positive electrode and the negative electrode of the iron material into the groundwater to perform an electrochemical reaction, and the iron is eluted into the groundwater, and dissolved oxygen in the groundwater reacts with iron to form an anaerobic environment to remove microorganisms;
    (b)상기 지하수에 산소를 공급하여 용존된 철이 수산화물 형태로 침전시키며, 철이 침전되는 과정에서 상기 지하수 내 중금속을 수산화물 형태의 철에 흡착 및 공침시켜 제거하는 단계; 및 (b) supplying oxygen to the ground water to precipitate dissolved iron in hydroxide form, and removing heavy metals in the ground water by adsorbing and co-precipitation to iron in hydroxide form during the precipitation of iron; And
    (c)상기 지하수 내 침전물과 상등수를 상호 분리하는 단계;를 구비하는 것을 특징으로 하는 중금속 및 미생물 복합 오염 지하수 처리방법. (c) separating the sediment and the supernatant from each other in the groundwater; heavy metal and microbial complex contamination groundwater treatment method comprising the.
  7. 제6항에 있어서,The method of claim 6,
    상기 중금속은 비소를 포함하며,The heavy metal comprises arsenic,
    상기 미생물은 호기성 미생물인 것을 특징으로 하는 중금속 및 미생물 복합 오염 지하수 처리방법. The microorganisms are aerobic microorganisms, characterized in that heavy metals and microorganisms complex pollution groundwater treatment method.
PCT/KR2018/006773 2017-06-15 2018-06-15 System and method for treating underground water synthetically contaminated by heavy metal and microorganism WO2018230998A1 (en)

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