• Journal of Korean Society of Environmental Engineers
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• v.39 no.12
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• pp.664-671
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• 2017

Non-point source pollution is the emission source that unspecifically releases pollutants to water system from unspecific places such as cities, agricultural lands, mountains, and construction sites and its discharge path is not easily identified. Also, it is difficult to design and manage the reduction facilities for the emission quantity is primarily affected from weather conditions like rainfall. Since 2006, the significance of non-point source pollution reduction has been grown in Republic of Korea and this reinforces needs for the installation of reduction facilities. However, because the standards for the installation details and reduction efficiency are not clarified by law, people are preferring technologies that do not require particular maintenance and high expenses. The purpose of this study is to examine and maintain the efficiency of non-point source pollutants reduction facility which uses expended polypropylene as a media. The higher the depth of the media, the less range of variations in the reduction efficiency was observed and the final efficiency was also increased. When the media depth was 60 cm, the average reduction efficiency was 94% and 90% where linear velocities were 10 m/hr and 20 m/hr respectively. The results from 180 minutes operation in 10 m/hr and 20 m/hr of linear velocities were slightly different in head loss changes which were caused by media depth variations. The backwash experiments which were conducted in triplicate showed the reduction efficiency decreased as the time went on because of the media clogging. However, it was found that after the backwashing the reduction efficiency was increased as effective as the efficiency of the initial filtration.

• Journal of Korean Society of Water and Wastewater
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• v.23 no.2
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• pp.207-214
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• 2009

This study examines the optimum filtration conditions in pretreatment of seawater desalination by reverse osmosis. For this purpose, Masan bay seawater is treated through a gravity filter column while $FeCl_3$ is added as coagulant. The conditions of coagulantd osage, media depth, filtration rate, and backwash time are evaluated. The study results show that the filtrate quality improved with increasing coagulant dosage, but head loss rapidly increased. After 4mg/L, the unit filter run volume reduced to less than $200m^3/m^2$. Considering the head loss development, 4mg/L is determined as the optimum dosage. The better filtrate qualities are obtained with depth of 100cm than that of 80cm. The two stage filtration, which outperformed the single stage filtration, is suggested for treatment of Masan bay. The filtration rate of 5m/h is decided as the optimum condition considering the head loss development. At 10m/h, the filtrate quality deteriorated even though the extent was minimal, and head loss increased rapidly. The backwash time of 10 min is decided appropriate.

• Journal of Wetlands Research
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• v.20 no.3
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• pp.263-271
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• 2018

In this study, we analyzed the removal efficiency of ammonia nitrogen and phosphate dependant on the column depths using various absorbents such as zeolite silica sand, and activated carbon through the column test. In addition, we analyzed electrochemical adsorption behaviors of ammonia nitrogen and phosphate through the quantum mechanical calculation based on density functional theory calculation. Experimental results represent the removal efficiency of ammonia nitrogen and phosphate are zeolite > activated carbon > silica sand, and activated carbon > zeolite > silica sand, respectively. Zeolite shows high adsorption property for ammonia nitrogen over 90%, regardless of the column depth, while activated carbon exhibits high adsorption property for both ammonia nitrogen and phosphate as the column depth for filter media increases. Theoretical findings using DFT calculation for the adsorption behaviors of adsorbents (activated carbon and silica sand) and nutrients ($PO_4{^{3-}}$, $NH_4{^{+}}$) show that activated carbon represented narrower HOMO-LUMO band gap with high adsorption energy, and even more favorable environment for electron adsorption than silica sand, which leads to the effective removal of nutrients.

• Journal of Korean Society of Environmental Engineers
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• v.39 no.4
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• pp.214-219
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• 2017

We analyzed the water quality of first flush and rainfall runoff from a building rooftop, and investigated the removal of suspended solids (SS) in first flush using various media to develop a first flush filtration system. Particle size distribution exhibited most of particles in first flush from the rooftop ranged from 10 to 30 ${\mu}m$. SS concentrations maxed in 10~20 min and decreased afterwards. Dissolved organics and inorganic materials in runoff also showed highest levels in first flush (10 min). Filtration tests using anthracite (AC), polyurethane (PU), polypropylene (PP) showed about 50% of SS removal during the first 10 min operation, but the removal rates dramatically decreased after 20 min of filtration. Based upon the results from rinse and run cycle tests, only AC could achieve nice cycles without distinct decease of SS removal. SS removal rates increased with higher depth of media bed and lower flowrate. The system achieved over 50% of SS removal with a media depth of 30 cm and flowrate < 12 L/min.