Minah Oh

Assessment of Soil Washing Efficiency for Arsenic Contaminated Site Adjacent to Jang Hang Refinery

Cause of contamination in the study area nearby Jang Hang Refinery is dust scattering in refinery stack, and soil washing treatment is one of the proper technologies for soil remediation in this area. Site conditions frequently limit the selection of a treatment process. A treatment technology may be eliminated based on the soil classification or physicochemical characteristics of soil. This study was assessed the soil washing efficiency by conducting of soil characteristic analysis in the vicinity of Jang Hang Refinery Stack within a 2 km radius. Also, it was decided about remedial range with comparative analysis of As in soil by Korean Standard Test Method before/after revision, whereupon As concentration in soil showed a increasing tendency after revision. As a result, the soil washing using the size separation of soil was determined through identifying of As species in the soil. In this site, only particle size distribution and water content of soil can provide the initial means of screening for the potential use of soil washing.

Settling and Filtering Process for the Treatment of Fine Suspended Solids and Soluble Heavy Metals in H Mine Drainage

Fine suspended solids generated effluence from treatment process of mine drainage could destroy environment as the aesthetic landscapes, and depreciate water quality. Therefore, the purpose of this research is focused on process development applied the actual field for controlling fine suspended solids and heavy metals, and so lab-scale test was performed for inducement of basic data. The mine drainage used in this research was sampled in H mine located Jeongseon-gun, Gangwon-do. Concentration of suspended solid, arsenic, iron and manganese was exceeded the standard of contaminant limitation for the clean water, and particle size of suspended solid was less than 10 m as fine particle. Although hydraulic retention time of mine drainage for effective settling was required more than 6 hours, hydraulic retention time would be increased in winter season when the settling efficiency could be reduced because of viscosity decreasing. Moreover, installed inclination plate helped to increase settling efficiency of suspended solid about 48 %. Filtering media that was the most effective removal of suspended solids and heavy metal was decided granular activated carbon of 1~2 mm was the optimal size.

Feasibility Tests for Treating Fine Suspended Solids from Mining Drainage, using Various Media by Column Methods - A Case from H Coal Mine

Fine suspended solids from mine drainage draw attentions due to their potential adverse influences on the water quality, such as increasing turbidity and degrading aesthetic landscape. Currently, sand filter beds are adapted in some mine drainage treating systems. However, more efficient system is in demand, as the existing sand beds reveal some problems, such as frequent maintenance intervals. Various filtering mediums including fly ash, mine tailing aggregates and the sand were tested for improving the current system, using column experimental set-up. Mine drainage samples were collected from the current treating systems in the abandoned H coal mine. The experiment was run for 7 days. Suspended solids recorded as 100.9 mg/L and the value exceeds the current standard, 30 mg/L. Sand was proved to still be the optimum medium for the fine suspended solids, compared to fly ash and fly ash + sand. Mine tailing aggregates were placed at the exit of the columns, substituting gravels. The tailing aggregates is made by mine tailings and clay. Sand bed filters can also be improved by mixing granular activated carbon, which was found to be economical and efficient in the batch experiment, conducted at the same time.

Removal of As and Heavy Metals (Cd, Cu, Pb) in Soil Washed Fine Soil Using Enhanced Electrochemistry

The soil washing is broadly used by treating amount of soil for a short period. However, soil washing has 2 kinds of disadvantage that the efficiency is very low in fine soil with low permeability, and highly concentrated fine soil after the process has to designate and dispose as the hazardous waste. Thus, treatment of fine soil contaminated arsenic and heavy metals after soil washing is focused in this study, and electrokinetic remediation as known as having high efficiency in soil with low permeability is selected. Moreover, chelating agents which could be changed from fraction to remove difficult to treatable fraction are applied to enhance the effect of electrokinetic remediation. The condition of chelating agent was selected to 50 mM Na_2EDTA adjusted pH 12 through the batch tests. In the result of operating units, the experiment which not only controlled the pumping velocity for preventing extremely acidic pH around anode, but also impregnated fine soil with 50 mM Na_2EDTA adjusted pH 12 is the most effective removal rate as arsenic, cadmium, copper and lead are 73.68%, 13.18%, 38.41% and 33.23% respectively.

A Study on the Characteristics of the Biochar by Hydrothermal Carbonization with Food Waste

ABSTRACT Hydrothermal carbonization (HTC) is a carbonization method of thermochemical process at a relatively low temperature(180-250 o C). It is reacted by water containing raw material. In this study, it was selected for effective disposal method offood waste because food waste in Korea has large amount water. 5 kg, 10 kg, 15 kg of food waste were reacted for 6 hoursat 200 o C for selecting the optimum amount of raw material. Since the derived optimum amount, food waste was reactedfor 2 hours, 4 hours and 6 hours at 200 o C and 1.5 MPa. After carbonization, it was analyzed to evaluated the properties byultimate analysis, iodine adsorption, BET surface area and SEM. After analyzing the characteristics, it can be utilized as abasic data for applied. Key words : Hydrothermal carbonization, Biochar, Food waste 1. 서론 2012년 우리나라 음식물 폐기물은 발생량은 13,209 톤/일이며, 이는 전체 폐기물 발생량의 약 27%에 해당하는양으로 매년 증가하는 추세를 보인다(Ministry of Enviro-nment, 2012). 하지만 폐기물 관리법 시행규칙 개정으로인해 2005년부터 매립이 금지되고, 최근 런던 협약에 의해 유기성 폐기물의 해양 투기도 전면 금지됨에 따라 음식물 폐기물의 처리 대안이 시급하게 요구되고 있다. 현재 시행되고 있는 음식물 폐기물의 처리 방법에는 퇴비화,소각화, 사료화, 재활용 등이 있으나, 우리나라 음식물의경우 다량의 염분과 수분을 함유하고 있어 위의 방법을적용하기 어려움이 있어 재활용이 저조한 실정이다.일반적으로 음식물 폐기물과 같은 유기성 폐기물을 재활용 가능한 물질로 전환시키는 방법으로는 생화학적, 화학적, 열화학적 방법 등이 있으며, 이 중 열화학적 방법은크게 high temperature pyrolysis(고온열분해법)과 hydro-thermal carbonization(HTC, 열수가압탄화법)으로 나뉜다(Bae, 2011). HTC는 대상물질이 180-250

Removal of As, Cadmium and Lead in Sandy Soil with Sonification-Electrokinetic Remediation

The actively soil pollution by the toxic heavy-metals like the arsenic, cadmium, lead due to the industrialization and economic activity. The uses the electrokinetic remediation of contaminated soil has many researches against the fine soil having a small size in the on going. However, it is the actual condition which the research result that is not effective due to the low surface charge of the particle and high permeability shows in the electrokinetic remediation in comparison with the fine soil in the case of the sandy soil in which the particle size is large. In this research, the electrokinetic remediation and ultrasonic wave fetch strategy is compound applied against the sandy soil polluted by the arsenic, cadmium, and lead removal efficiency of the sandy soil through the comparison with the existing electrokinetic remediation tries to be evaluated. First of all, desorption of contaminants in soil by ultrasonic extraction in the Pre-Test conducted to see desorption effective 5~15%. After that, By conducted Batch-Test results frequency output century 200 Khz, reaction time 30 min, contaminated soil used in experiment was 500 g. Removal efficiency of arsenic, cadmium, lead are 25.55%, 8.01%, 34.90%. But, As, Cd, Pb remediation efficiency less than 1% in EK1(control group).

Geochemical Reaction Processes and Controls on the Coal Mine Drainage using Pilot-scale Inclined Clarifiers

Abstract Fine suspended solids from coal mine drainage were treated in the treating plant, using two different pilot-scale inclinedclarifiers: radial and lamella types. Suspended solids in the mine drainage were monitored along with other geochemicalfactors, and metal contents. Fe and Mn are the main chemical components in the drainage, which exist predominantly astotal metal forms, whereas dissolved portion is negligible. The raw mine drainage is subject to physical and chemicaltreatment using CaCO 3 and NaOH ,therefore the suspended solids are thought to be composed of Fe and Mn precipitates,possibly Fe(OH) 3 , along with carbonate precipitates. The elemental composition of precipitates are confirmed by SEM-EDS analysis. As nearly all the dissolved ions were precipitated in the primary process by CaCO 3 , no further aeration orprolonged oxygenation are of necessity in this plant. Adoption of inclined clarifier proved to be effective in treating finesuspended solids in the current plant. Successful application of the inclined clarifier will also be beneficial to improve thecurrent treating process by excluding the current application of chemical agent in the first stage. The final effluents fromthe pilot plant meet the national standards and the low dissolved Fe and Mn contents are expected not to cause secondaryprecipitation after discharge. Key words :Coal mine drainage, Suspended solids, Fe precipitates, Sand bed, Inclined clarifier

A Study on the Modified Fenton Oxidation of MTBE in Groundwater with Permeable Reactive Barrier using Waste Zero-valent Iron

MTBE (Methyl tertiary-butyl ether) has been commonly used as an octane enhancer to replace tetraethyl lead in gasoline, because MTBE increases the efficiency of combustion and decreases the emission of carbon monoxide. However, MTBE has been found in groundwater from the fuel spills and leaks in the UST (Underground Storage Tank). Fentons oxidation, an advanced oxidation catalyzed with ferrous iron, is successful in removing MTBE in groundwater. However, Fentons oxidation requires the continuous addition of dissolved Fe 2+ . Zero-valent iron is available as a source of catalytic ferrous iron of MFO (Modified Fentons Oxidation) and has been studied for use in PRBs (Permeable Reactive Barriers) as a reactive material. Therefore, this study investigated the condition of optimization in MFO-PRBs using waste zero-valent iron (ZVI) with the waste steel scrap to treat MTBE contaminated groundwater. Batch tests were examined to find optimal molar ratio of MTBE : H2O2 on extent to degradation of MTBE in groundwater at pH 7 with 10% waste ZVI. As the results, the ratio of optimization of MTBE to hydrogen peroxide for MFO was determined to be 1:300[mM]. The column experiment was conducted to know applicability of MFO-PRBs for MTBE remediation in groundwater. As the results of column test, MTBE was removed 87% of the initial concentration during 120days of operational period. Interestingly, MTBE was degraded not only within waste ZVI column but also within sand column. It means the aquifer may affect continuously the MTBE contaminated groundwater after throughout the waste ZVI barrier. The residual products showed acetone, TBF (Tert-butyl formate) and TBA (Tert-butyl acetate) during this test. The results of the present study showed that the recycled materials can be effectively used for not only a source of catalytic ferrous iron but also a reactive material of the MFO-PRBs to remove MTBE in groundwater. Key word : Waste Zero-Valent Iron, MTBE, Modified Fenton Oxidation, PRBs, MFO-PRBs