• Membrane Journal
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• v.29 no.5
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• pp.237-245
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• 2019

Ammonia nitrogen is well known as a substance that causes the eutrophication with a phosphorus in the water, because it is contained in the industrial wastewater, agricultural and the stockbreeding wastewater. In addition, manganese (Mn) and arsenic (As) are included in the mine treated water, etc., and are known as a source of water pollution. Natural zeolites are used to remove ammonia nitrogen in water but it have a low adsorption capacity. In order to improve the low adsorption capacity of the natural zeolite, ion substitution was carried out with $Na^+$, $Ca^{2+}$, $K^+$ and $Mg^{2+}$. The adsorption capacity and removal rate of ammonia nitrogen ($NH_4-N$) were the highest at 0.66 mg/g and 89.8% in $Na^+$ ion exchanged zeolite. Adsorption experiments of Mn and As were performed using ion exchanged zeolites. Ion exchanged zeolite with $Mg^{2+}$ showed high adsorption capacity and removal rates of Mn and As.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.8
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• pp.878-883
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• 2006

Removal efficiency of As(III) was investigated with a pilot-scale filtration system packed with an equal amount(each 21.5 kg) of manganese-coated sand(MCS) in the bottom and iron-coated sand(ICS) in the top. Height and diameter of the used column was 200 cm and 15 cm, respectively. The As(III) solution was introduced into the bottom of the filtration system with a peristaltic pump at a speed of $5{\times}10^{-3}$ cm/s over 148 days. Breakthrough of total arsenic in the mid-sampling position(end of the MCS bed) and final-sampling position(end of the ICS bed) was started after 18 and 44 days, respectively, and then showed a complete breakthrough after 148 days. Although the breakthrough of total arsenic in the mid-sampling position was started after 18 days, the concentration of As(III) in this effluent was below 50 ppb up to 61 days. This result indicates that MCS has a sufficient oxidizing capacity to As(III) and can oxidize 92 mg of As(III) with 1 kg of MCS up to 61 days. When a complete breakthrough of total arsenic occurred, the removed total arsenic by MCS was calculated as 79.0 mg with 1 kg MCS. As variation of head loss is small at each sampling position over the entire reaction time, it was possible to operate the filtration system with ICS and MCS for a long time without a significant head loss.

• Journal of Soil and Groundwater Environment
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• v.10 no.6
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• pp.68-74
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• 2005

This study was carried out to evaluate the feasibility of field-scale sequential soil washing process for remediation on Kyongsangnamdo D mine soils which was heavily contaminated by arsonic. Arsenic concentration of untreated soils was $321\pm32mg/kg$. By applying the basic operating condition which was proposed from several pilot-scale experiments, arsenic concentration of treated soils was reduced 2.04 mg/kg ($99\%$ removal efficiency). We optimized the basic operating condition (mainly on washing solution concentration, cut-off size, and mixing ratio) to improve efficiently and economically the field-scale sequential soil washing process. The resulting optimized conditions were that solution concentration is 0.2M HCl, 1.0M HCl, 1.0M NaOH, that the cut-off size is 0.15mm (seive $\sharp$100), and that the mixing ratio is 1 3. Also, the optimized pH value for soil washing effluent treatment was 6 (33 ppb), in which the precipitation disruption caused by supersaturation of the floe did not occur. Results of TCLP tests showed that arsenic concentration from the washed gravels was 1.043 mg/L, that from soils ND (not detected), and that from filter cakes 0.066 mg/L. Also, the water content as a percentage of dewatered sludges was low $(48\%)$ and so the dewatered sludges can be disposed by landfilling. Through these results, we can concluded that tile field-scale sequential soil washing process developed in this study is adopted for remediation of arsenic-contaminated soils.

• Journal of Environmental Science International
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• v.20 no.2
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• pp.241-249
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• 2011

In this research, equilibrium of adsorption and kinetics of As(V) removal were investigated. The coal mine drainage sludge(CMDS) was used as adsorbent. To find out the physical and chemical properties of CMDS, XRD (X-ray diffraction), XRF (X-ray fluorescence spectrometer) analysis were carried out. The CMDS was consist of 70% of goethite and 30% of calcite. From the results, an adsorption mechanism of As(V) with CMDS was dominated by iron oxides. Langmuir adsorption isotherm model was fitted well more than Freundlich isotherm adsorption model. Adsorption capacities of CMDS 1 was not different with CMDS 2 on aspect of amounts of arsenic adsorbed. The maximum adsorption amount of two CMDS were respectively 40.816, 39.682 mg/g. However, the kinetic of two CMDS was different. The kinetic was followed pseudo second order model than pseudo first order model. Concentrations of arsenic in all segments of the polymer in CMDS 2 does not have a constant value, but the rate was greater than the value of CMDS 1. Therefore, CMDS 2, which is containing polymer, is more effective for adsorbent to remove As(V).

• Journal of the Korean Wood Science and Technology
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• v.31 no.4
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• pp.50-56
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• 2003

This research was performed to select an appropriate agent to extract preservative components from CCA-treated wood, and then to evaluate the effect of reagent concentration, extracting temperature, and extracting time on the removal of chrome, copper, and arsenic from treated wood. Hydrogen peroxide was selected as the best extracting agent when considered extraction yield as well as use and environmental safety. Its extraction yield was dependent on extracting variables (temperature, concentration, and time), and a highly significant interaction existed among variables. It should be possible to optimize extraction by manipulating these extracting variables. The results may suggest that the required temperature conditions for the reasonable removal of CCA components are at least above 40℃ because extracting time is too long at low temperature (20℃). Reagent concentrations for extracting at above 40℃ should be decided by considering the extracting time.

• Textile Coloration and Finishing
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• v.33 no.4
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• pp.250-257
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• 2021

Laundry industry has traditionally been considered an industry that generates large amounts of wastewater and Volatile Organic Compounds(VOCs). This is still the case until now. Household laundry detergents are produced and distributed within the safety regulations on the amount of harmful substances detected. While industrial laundry detergents are often distributed without safety regulations, and even laundry workers manufacture and use them on their own. This contaminates water and air and also threatens the safety of workers. This study is a basic study for distributing eco-friendly detergents(EFD-A) developed through previous studies to the laundry industry. Safety, washability and wastewater quality of EFD-A are evaluated. Three existing commercial detergents(PD1, PD2, LD4) are also evaluated to compare with EFD-A. The safety of detergents is confirmed by the content of optical brightener, VOCs, and arsenic. Washability is evaluated by the difference in reflectance of washed and unwashed artificial soiled fabrics according to detergent concentration, washing temperature, and washing time. TOC is used as the index of assessing the wastewater quality. The results are as follows; EFD-A doesn't contain the optical brighteners, VOCs, and arsenic. The optimal washing conditions for EFD-A are 3 g/L concentration, 40 ℃ washing temperature, and 30 min washing time. The soil removal efficiency is about 71 %, which was similar to or somewhat superior to that of PD1, PD2, and LD4. TOC is 63.5 %, which is about 15 % lower than the discharge limit. Through this study, the developed detergent EFD-A can be used as a safe and eco-friendly detergent for the human body and the environment.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.1
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• pp.149-157
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• 2000

This paper presents the first results of dissolved arsenic in the Kangnung Namdae stream. The distribution of As concentrations measured in 28 August (high water flow) and in 21 November 1997 (low water flow) differs from those of other metals measured during the same period; The concentrations of Doam-dam are lower than those of Obong-dam and accumulation in the downstream in the period of low water flow is not pronounced. The As concentration in the downstream under the low water flow is lower than under high water flow, reciprocally to other metals. Freshwater concentrations are comparable with those measured in pristine river and lower than the world average and the diffrence of concentrations measured during two period is minute. Therefore, the As concentrations in the Namdae stream are background level and the source of As contamination does not exist. In the mixing zone between the freshwater and Donghae seawater, As behave conservatively, indicating the absence of any significant removal or mobilization processes. A first estimation of total dissolved As input from Namdae stream to Donghae coastal sea shows 65.12 kg/yr.

• Journal of Soil and Groundwater Environment
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• v.24 no.4
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• pp.1-10
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• 2019

Recently, groundwater contamination by mixed occurrence of arsenic (As) and nitrate ($NO_3{^-}$) has been a serious environmental issue all around world. In this study, we investigated the microbial As(III) oxidation characteristic under denitrification process to examine the feasibility of the microbial consortia in wetland sediment to simultaneously treat these two contaminants. The detail objectives of this study were to investigate the effects of $NO_3{^-}$ on the oxidation of As(III) in anaerobic environments and observe the microbial community change during the As oxidation under denitrification process. Results showed that the As(III) was completely and simultaneously oxidized to As(V) under denitrification process, however, it occurred to a much less extent in the absence of sediment or $NO_3{^-}$. In addition, the significant increase of As(III) oxidation rate in the presence of $NO_3{^-}$ suggested the potential of As oxidation under denitrification by indigenous microorganisms in wetland sediment. Genera Pseudogulbenkiania, and Flavisolibacter were identified as predominant microbial species driving the redox process. Conclusively, this study can provide useful information on As(III) oxidation under denitrifying environment and contribute to develop an effective technology for simultaneous removal of As(III) and $NO_3{^-}$ in groundwater.

• Journal of Soil and Groundwater Environment
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• v.18 no.3
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• pp.58-64
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• 2013

This study proposed a low temperature hydrothermal carbonization to treat and recycle sewage sludge and determined the optimal conditions for the biochar production. The physical and chemical properties of biochar were analyzed and its sorption capacity for heavy metals was evaluated. To produce biochar, 50 g of sewage sludge was heated at 220, 230, and $240^{\circ}C$ for 1, 2, 3, 5, 8, and 10 hours in a reactor. The optimal conditions to produce biochar was $230^{\circ}C$ and 8 hours. Sorption capacity tests were conducted for arsenic (As), cadmium (Cd), copper (Cu), lead (Pb), zinc (Zn) and nickel (Ni). Among them, lead was shown the highest heavy metal adsorption efficiency of biochar, followed by copper, cadmium, zinc, and nickel, but arsenic was hardly adsorbed overall.

• Progress in Superconductivity and Cryogenics
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• v.22 no.2
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• pp.1-6
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• 2020

Large-scale civil engineering works discharge a large amount of soil suspension contaminated with natural heavy metals. Most of the heavy metal ions due to industrial activities and minings are accumulated in the soils and the sediments of lakes and inner bays through the rivers. It is necessary to remove heavy metals from the soils and the sediments, because some of these heavy metals, such as arsenic and cadmium, have significant biological effects even in small amounts. This study proposes a new volume reduction method of the contaminated soils and sediments by superconducting magnetic separation. Our process can remove the specific minute minerals selectively, which adsorbs heavy metals depending on pH. As a fundamental study, the adsorption behaviors of arsenic and cadmium on minute minerals as a function of pH were investigated, and the adsorption mechanism was discussed based on the crystal structure and pH dependence of surface potential in each minute minerals.