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Chun S.-K.,Sudokwon Landfill Site Management Corporation
Journal of Material Cycles and Waste Management

When landfill gas is collected, air inflow into the landfill can reduce CH4 productivity. The decline of CH4 content in landfill gas (LFG) negatively affects energy projects. We studied air inflow rates and LFG characteristics from 699 vertical collection facilities (VCFs) in the 2nd landfill at the Sudokwon Landfill in South Korea. We first determined whether or not N2 was an effective indicator of air inflow at this site using argon assays. The results of this analysis showed that the denitrification processes could be disregarded and that N2 was an effective indicator of air inflow. Using the composition of N2 in LFG samples, we found that air inflow occurred at 73.6 % of the VCFs, and 25.6 % of samples from these facilities showed more than 80 vol% of air inflow. In addition, we observed that the O2 consumption rate was more than 70 % of the volume in all samples. RCH4, which is the ratio of CH4 to the sum of CH4 and CO2, decreased with increasing air inflow. Finally, we found that, as air inflow increased, the variation in RCH4 values for samples with equal air inflow ratios also increased due to differences in air inflow routes. © 2013 Springer Japan. Source

Jeon S.-B.,Pusan National University | Jung J.-H.,Daegu Haany University | Lee H.-D.,Sudokwon Landfill Site Management Corporation | Kim B.-J.,Pusan National University | Oh K.-J.,Pusan National University
International Journal of Greenhouse Gas Control

Speciation and kinetics of carbon dioxide absorption by N-methylcyclohexylamine (MCHA) and 2,6-dimethylpiperidine (DMPD) emulsion absorbents were evaluated. The physical solubility, diffusivity, and carbon dioxide absorption rate were measured as a function of temperature (293, 303, 313, and 323K) and amine concentration (10, 20, 30, and 40wt%) by using a semibatch reactor and wetted wall column (WWC). The results showed that the rate of carbon dioxide absorption by the MCHA and DMPD emulsion absorbents increased with the carbon dioxide partial pressure and amine concentration. Using the physical data and absorption rate, the rate constants for carbon dioxide absorption by MCHA and DMPD were evaluated. Based on the pseudo-first-order reaction, the rate constants were determined to be k2,MCHA=2.698×107exp(-2458/T) and k2,DMPD=1.002×106exp(-1511/T). Notably, the activation energies for carbon dioxide absorption by the emulsion absorbents containing MCHA or DMPD were lower than those of alkanolamine solutions. © 2015 Elsevier Ltd. Source

Chun S.-K.,Sudokwon Landfill Site Management Corporation
Environmental Engineering Research

Analysis of hydrological safety as well as the determination of many substance concentrations are necessary when bioreactor systems are introduced to landfill operations. Therefore, hydrological and substance balance model was developed since it can be applied to various bioreactor landfill operation systems. For the final evaluation of the model's effectiveness, four different methods of injections (leachate alone, leachate and organic waste water, leachate and reverse osmosis concentrate, and all the above three combination) was applied to 1st landfill site of Sudokwon landfill. As a result, the water content of the hypothetical cases for four different systematic bioreactors is projected to be increased up to 35.5% in next 10 years, and this indicated that there will be no problems in meeting the hydrological safety. Also, the final Cl- concentration after 10-yr time period was projected to be between from minimum 126 to maximum 3,238 mg/L, which could be still a decrease from the original value of 3,278 mg/L. According to the proposed model, whether the substance concentration becomes increased or decreased largely depends on the ratio of initial quantity of inner landfill leachate and the rate of injection. © The Korean Society of Environmental Engineers. Source

Ly S.-Y.,Seoul National University of Science and Technology | Yoo H.-S.,Korea Ocean RandD Institute | Chun S.-K.,Sudokwon Landfill Site Management Corporation
Food Chemistry

The presence of trace metal cadmium assay was investigated with a copper immobilized on a graphite carbon electrode (GPC), the modified property of which was determined with handheld voltammetric systems. Following the determination of the analytical stripping conditions of 0.45 V amplitude, 30 Hz frequency, -1.4 V initial potential, and 4.0 mV increment potential, only a 60-s experimental accumulation time was used. Using these conditions, the analytical detection limit approached the nano range. At this condition, the analytical application was performed on distilled alcoholic drinks for food manufacturing systems. This developed technique is faster and less costly than the common voltammetric and spectrophotometric methods. © 2012 Elsevier Ltd. All rights reserved. Source

Kim N.-J.,Seoul National University of Science and Technology | Chun S.-K.,Sudokwon Landfill Site Management Corporation | Cha D.K.,University of Delaware | Kim C.,Seoul National University of Science and Technology
Bulletin of the Korean Chemical Society

The objective of this study was to develop a simple, less time-consuming and accurate sampling technique based on solid-phase sorption with activated carbon as the sorbents. The results from solid-phase sorption techniques were compared to that from a conventional solvent impinger-based technique to confirm the efficacy of the proposed method. The laboratory results indicated that the solid-phase sorption method was suitable for the determination of siloxanes as the measured concentrations were similar to that from a solvent impinge method. The data from solid-phase sorption method showed excellent recovery and reproducibility while the sampling was less labor intensive and less time consuming than the solvent impinge method. Following the laboratory tests, the solid-phase sorption technique was successfully applied to sampling biogas from a field site. This study shows that the activated carbon-based solid-phase sorption can be a reliable and less time-consuming option for the sampling and collection of siloxanes under various different landfill conditions. Source

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