• Korean Journal of Food Science and Technology
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• v.53 no.2
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• pp.218-222
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• 2021

This study aimed to investigate bacterial disinfection in drinking water using a water purifier. Water artificially inoculated with Escherichia coli and Listeria monocytogenes at various concentrations was irradiated using ultraviolet (UV)-C at a rate of 3.4 L/min in a water purifier, and the disinfection effects of UV-C were evaluated. Both E. coli and L. monocytogenes were disinfected up to 107 colony-forming units (CFU)/2.8 L by the UV-C irradiation. Additionally, morphological study using fluorescence microscopy in conjunction with live/dead staining revealed that both the bacteria species were disinfected by the UV-C irradiation. Therefore, UV-C in water purifiers can effectively kill high concentrations of bacteria in distilled water. UV irradiation (UV-C: 254 nm wavelength, irradiation dose: 40 mJ/㎠) at a flow rate of 3.4 L/min on drinking water has the potential to sterilize bacteria-contaminated drinking water, at least for 3.2×107 CFU/2.8 L of E. coli and 8.4×107 CFU/2.8 L of L. monocytogenes.

• Applied Chemistry for Engineering
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• v.33 no.3
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• pp.235-241
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• 2022

According to the World Water Development Report 2015 released by the United Nations, drinking water is expected to decrease by 40% by 2030. This does not mean that the amount of water decreases, but rather that the water source is contaminated due to environmental pollution. Because microbes are deeply related to water quality, the analysis of microbe is very important for water quality management. While the most common method currently used for microbial analysis is microscopic examination of the shape and feature after cell culture, as the gene analysis technology advances, quantitative polymerase chain reaction (qPCR) can be applied to the microscopic microbiological analysis, and the application method has been studied. Among them, a reverse transcription (RT) step enables the analysis of RNA by RT-PCR. Integrated cell culture (ICC)-qPCR shortens the test time by using it with microbial culture analysis, and viability qPCR can reduce the false positive errors of samples collected from natural water source. Multiplex qPCR for improved throughput, and microfluidic qPCR for analysis with limited amount of sample has been developed In this paper, we introduce the case, principle and development direction of the qPCR method applied to the analysis of microorganisms.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.24 no.5
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• pp.454-460
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• 2012

The purpose of the present work is to investigate the removal characteristics of positively charged filters for capturing negatively charged particles such as bacteria and virus in water. In order to reduce the pressure drop and increase the filtration efficiency, the filter media, modified by charge modifier having positive functional groups, is developed and evaluated. Improved liquid filters have been developed with the modified surface charge to capture and adsorb particles by electrokinetic interaction between the filter surface and particles contained in an aqueous liquid. The positively charged filter media is composed of glass fiber, cellulose and poly-ethylenimine resin for positively charging with the variation of volume ratio. The zeta potential value of the positively charged filter is +37.92 mV at the glass fiber and cellulose content ratio of 50 : 50 with resin content of 100%, while that of the PSL test particle is -23.5 mV at pH 7. The removal efficiency of the electro-positively charged filter is 98% for PSL particles of 0.11 ${\mu}m$, while that of the negatively charged filter is 7%. The positively charged filter media showed the potential to be an effective method for removing fine particles from the contaminated water for liquid filtration.

• Journal of Soil and Groundwater Environment
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• v.20 no.6
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• pp.85-94
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• 2015

RDX (hexahydro-1,3,5-trinitro-1,3,5-triazine) is the most important explosive contaminant, both in concentration and in frequency, at military shooting ranges in which green technologies such as phytoremediation or constructed wetlands are the best option for mitigation of explosive compounds discharge to the environment. A study was conducted with two identical lab-scale plug flow constructed wetlands planted with Amur silver grass to treat water artificially contaminated with 40 mg/L of toxic explosive compound, RDX. The reactor was inoculated with or without RDX degrading mixed culture to evaluate plant-microorganism interactions in RDX removal, transformation products distribution, and kinetic constants. RDX and its metabolites in water, plant, and sediment were analyzed by HPLC to determine mass balance and kinetic constants. After 30 days of operation, the reactor reached steady-state at which more than 99% of RDX was removed with or without the mixed culture inoculation. The major transformation product was TNX (Trinitroso-RDX) that comprised approximately 50% in the mass balance of both reactors. It was also the major compound in the plant root and shoot system. Acute toxicity analysis of the water samples showed more than 30% of toxicity reduction in the effluent than that of influent containing 40 mg/L of RDX. In the Amur silver grass mesocosm seeded with the mixed culture, the specific RDX removal rate, that is 1st order removal rate normalized to plant fresh weight, was estimated to be 0.84 kg⁻¹ day⁻¹ which is 16.7% higher than that in the planted only mesocosm. Therefore, the results of this study proved that Amur silver grass is an effective plant for RDX removal in constructed wetlands and the efficiency can be increased even more when applied with RDX degrading microbial consortia.

• Journal of Soil and Groundwater Environment
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• v.17 no.2
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• pp.28-36
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• 2012

This study carried out several kinds of investigations such as geology, hydrogeology, groundwater level and quality, surface-water quality, and the quantity and quality of groundwater discharge from the subway to identify the causes of groundwater contamination around the subway tunnel at Suyeong District in Busan City. Geostatistical analyses were also conducted to understand the characteristics of groundwater level and quality distributions. There are Kwanganri Beach and Suyeong River in the study area, which are basically influenced by seawater. The total quantities of groundwater utilization and groundwater discharge from the subway tunnel in Suyeong District are 2,282,000 $m^3$/year, which is 2.4 times larger than the sustainable development yield of groundwater. The lowest groundwater level around the subway tunnel is about 32 m below the mean sea-level. The large drawdown of groundwater led to the inflow of seawater and salinized river water toward the subway tunnel, and therefore the quality of groundwater didn't satisfy the criteria of potable, domestic, agricultural and industrial uses. Distribution maps of groundwater level and qualities produced by kriging were very useful for determining the causes of groundwater contamination in the study area. The distribution maps of electrical conductivity, chloride and sulfate showed the extent of seawater intrusion and the forceful infiltration of the salinized Suyeong River. This study revealed that seawater and salinized river water infiltrated into the inland groundwater and contaminated the groundwater around the subway tunnel, because the groundwater level was seriously drawdowned by groundwater discharge from the subway tunnel. The countermeasure for the minimization of groundwater discharge from the subway tunnel is necessary to prevent the groundwater obstacles such as groundwater depletion, groundwater-quality deterioration, and land subsidence.

• Journal of Soil and Groundwater Environment
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• v.15 no.4
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• pp.21-29
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• 2010

As the target area of this study, the coal mine site of Dongwon Sabuk mine.,ltd. is located in the remote mountainous region. To purify the acid mine water contaminated with heavy metals, a pilot-scale plant was built at the surrounded area of a mine shaft and operated to simulate active treatment system that could not only possibly setup the facility in a small available area, but also has a high efficiency. According to the various conditions of basin sequence, existence of sludge return, and lime injection position, six different types of treatment series were investigated in terms of treatment efficiency. As a result, the aluminum concentrations of the most effluents were in the range of 0.005~0.030 mg/L, which was too low to compare. The manganese concentration in the treated water were in the range of 3~9 mg/L, not following any regular trend. As found in the results of iron concentration, the case of addition of oxidation and sludge return steps showed higher efficiency than the others. As a standpoint of the installation of full-scale physicochemical treatment facility, the experimental results showed that the batch of oxidation and high density sludge return processes are existed and neutralization was followed by oxidation, had a stable treatment efficiency.

• Journal of the Korea Organic Resources Recycling Association
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• v.16 no.1
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• pp.46-52
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• 2008

Oils and chlorinated solvents leaking to the subsurface are entrapped in the soil pore and these are called as nonaqueous phase liquids (NAPL). NAPL entrapped in porous media acts as a continuous source for surface and ground water contamination. This study visualized dissolution of trichloroethylene (TCE) entrapped in porous media and quantified the velocity of TCE dissolution using an image analysis technique. As the water velocity increased, the level of dissolution increased. The results imply that a TCE contaminated region having a high infiltration rate and groundwater velocity may result in severe groundwater contamination. Microscopic images of TCE entrapped in porous media showed that TCE present in the preferential flow paths was easily dissoluted into the water phase. However, TCE present in the stagnant flow region was visualized for long time. The results imply that TCE would be still present in the soil if TCE is detected in goundwater.

• Environmental Engineering Research
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• v.25 no.2
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• pp.230-237
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• 2020

Nitrogen flux release from organically enriched sediments into overlying water, which may have significantly influence on water quality and increasing continuous eutrophication. The purpose of this study is to evaluate the remediation efficiency of oyster shell powder and its treated product into organically enriched sediment in terms of nitrogen flux, organic matter, chlorophyll-a, pH and dissolved oxygen (DO). The TOSP was mainly composed of CaO2. The application of TOSP into the sediment has increased the pH, DO and significantly decreased the concentrations of NH₄⁺-N and T-N compared to other basins. On the other hand, nitrate was enriched with the addition of treated oyster powder, an oxygen releasing compound on both phases. Furthermore, chlorophyll-a was found to be increasing with time in the control basin meanwhile it dropped drastically with the addition of TOSP, which implied on the repression of algal growth owing to blockage of nitrogen source migrating from the sediment. This study has shown that the TOSP was effective to improve sediment-water quality, diminish eutrophication and control harmful algae blooms in a marine environment. Therefore, it is a good reference as an effective environmental remediation agent.

• Journal of Microbiology and Biotechnology
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• v.23 no.11
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• pp.1598-1609
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• 2013

Organochlorine pesticide residues continue to remain as a major environmental threat worldwide. Lindane is an organochlorine pesticide widely used as an acaricide in medicine and agriculture. In the present study, a new lindane-degrading yeast strain, Pseudozyma VITJzN01, was identified as a copious producer of glycolipid biosurfactant. The glycolipid structure and type were elucidated by FTIR, NMR spectroscopy, and GC-MS analysis. The surface activity and stability of the glycolipid was analyzed. The glycolipids, characterized as mannosylerythritol lipids (MELs), exhibited excellent surface active properties and the surface tension of water was reduced to 29 mN/m. The glycolipid was stable over a wide range of pH, temperature, and salinity, showing a very low CMC of 25 mg/l. Bio-microemulsion of olive oil-in-water (O/W) was prepared using the purified biosurfactant without addition of any synthetic cosurfactants, for lindane solubilization and enhanced degradation assay in liquid and soil slurry. The O/W bio-microemulsions enhanced the solubility of lindane up to 40-folds. Degradation of lindane (700 mg/l) by VITJzN01 in liquid medium amended with bio-microemulsions was found to be enhanced by 36% in 2 days, compared with degradation in 12 days in the absence of bio-microemulsions. Lindane-spiked soil slurry incubated with bio-microemulsions also showed 20-40% enhanced degradation compared with the treatment with glycolipids or yeast alone. This is the first report on lindane degradation by Pseudozyma sp., and application of bio-microemulsions for enhanced lindane degradation. MEL-stabilized bio-microemulsions can serve as a potential tool for enhanced remediation of diverse lindane-contaminated environments.

• Proceedings of the Korea Contents Association Conference
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• 2009.05a
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• pp.1150-1158
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• 2009

Since equipment currently being used in the department of radiological technology comes into contact with patients carrying diseases, there inevitably will be the existence of pathogenic bacteria. Therefore, in order to increase the importance of using disinfectant in hospital infection precaution and the recognition of hospital infection management, comparisons were made by measuring the bacterial contamination levels in radiology room within the department of radiological technology and comparing the measurements with post disinfection levels. Disinfecting the rooms from detected bacteria was conducted with water, tissue cleaner, or 70% alcohol. When measuring bacterial contamination levels in radiology rooms, a variety of bacteria was detected. When disinfecting the interior of radiology rooms the effectiveness of destroying bacteria and preventing hospital infection was greatest when using 70% alcohol compared to water, tissue cleaner and ventilation. Therefore, there needs to be a development of a better antiseptic for destroying bacteria because there is a possibility for hospital medical equipment to be constantly contaminated. Efforts need to be made to prevent hospital infections and patient secondary infection by disinfecting and sterilizing equipment.