• Journal of Korean Society on Water Environment
• /
• v.24 no.6
• /
• pp.659-669
• /
• 2008

Two sets of four parallel activated sludge reactors (ASRs) maintaining an MLSS of 3000 mg/L were operated to investigate the effect of DO, HRTs and bio-contact media (BCM) packing ratios on the removal efficiency of organic matters and nitrogen. Packing ratios of BCM to BCM-ASR systems 1, 2, 3, and 4 were 0% (suspended growth only), 10%, 15% and 20%, respectively. All systems were operated at an HRT of 4 hr, 6 hr, and 8 hr, respectively; DO concentration was maintained 0.5~1.0 mg/L and 1.5~2.0 mg/L for each HRT condition. In terms of TSS, TCODcr and SCODcr removal efficiency, all systems had a similar level of the removal efficiency under varied HRTs, and DO. But organic removal efficiency of systems with BCM was approximately 3~5% higher than systems without BCM at the same HRT and the DO. About the nitrification efficiency, with high DO (1.5~2.0 mg/L), as HRT (4 hr, 6 hr, 8 hr) or BCM packing ratio increased, the slight increment of nitrification efficiency was observed. However, under the low DO (0.5~1.0 mg/L), increase of BCM packing ratio and HRT resulted in large increase of the nitrification efficiency. At the same HRT and BCM packing ratio, the nitrification efficiency increased greatly with up to 15% as DO increased. When the HRT increased from 4hr to 8hr, the denitrification efficiency slightly increased by 5~10% only, under all DO conditions. Systems with BCM had higher denitrification efficiency, ranged 62.7~91.1% than systems without BCM showed 32.1~65.6%. And the increase in BCM packing ratio from 10% to 20% resulted in about 14~16% denitrification efficiency increment. BCM packing ratio showed great effect on the denitrification. The increase of the DO (from 0.5~1.0 mg/L to 1.5~2.0 mg/L) at the same HRT and BCM packing ratio resulted in slight decrease of denitrification efficiency with up to 7% for systems with BCM. But for systems without BCM, the denitrification efficiency decreased with up to 28%. In all system, the denitrification efficiency had more influence on the TN removal efficiency than nitrification efficiency. So, BCM packing ratio (0%, 10%, 15%, 20%) has greater effect on the TN removal than HRT and DO. The TN removal efficiency increased as packing ratio of BCM increased with up to 45%. As a result, the highest TN removal efficiency was observed 73.7% at the condition showed the highest denitrification efficiency that DO of 0.5~1.0 mg/L, an HRT of 8 hr, and 20% of BCM packing ratio was maintained.

• Journal of People, Plants, and Environment
• /
• v.22 no.6
• /
• pp.551-561
• /
• 2019

This study was conducted to find out differences in the removal efficiency of particulate matter (PM) depending on the type of plants and the morphological characteristics of leaves. A total of 12 plants were used, with three plants selected for each type of leaves (big leaf, small leaf, compound leaf, needle leaf). We measured the removed amount of PM10 and PM2.5, the structure of the abaxial leaf surface, and the weight of the wax layer of each plant. Plants with the high removal efficiency of PM included Pachira aquatica Aubl., Ardisia crenata, and Dieffenbachia 'Marianne', and plants with the low removal efficiency included Nandina domestica Thunb, Schefflera arboricola, and Quercus dentata. The abaxial leaf surface having a high removal efficiency of PM had many large wrinkles, and the abaxial leaf surface having a medium removal efficiency was flat and smooth. On the other hand, there were many fine hairs on the abaxial leaf surface with a low removal efficiency. According to the plant leaf type, the PM10 removal efficiency of plants with needle leaves was about three times higher than that of other plants. In particular, the wax layer of conifers weighed 6-24 times higher than those of other plants. The stomata of conifers were evenly distributed on the adaxial and abaxial leaf surfaces; however, the stomata of Sciadopitys verticillata appeared in the form of papillae unlike general stomata. Therefore, the removal efficiency of PM varied depending on the macro-, and micro-morphological characteristics of plant leaves such as the structure of the abaxial leaf surface, and the weight of the wax layer. Based on this research, selecting plants that are effective in reducing PM in consideration of the plant type and leaf characteristics will improve indoor air quality and decrease exposure of PM to human body.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
• /
• 2003.09a
• /
• pp.78-82
• /
• 2003

Development of hematite-coated sand was evaluated for the application of the PRB (permeable reactive barrier) in the arsenic-contaminated subsurface of the metal mining areas. The removal efficiency of As(III) and As(V), the effect of anion competition and the capability of arsenic removal in the flow system were investigated through the experiments of adsorption isotherm, arsenic removal kinetics against anion competition and column removal. Hematite-coated sand followed a linear adsorption isotherm with high adsorption capacity at low level concentrations of arsenic (< 1.0 mg/l). When As(III) and As(V) underwent adsorption reactions in the presence of anions (sulfate, nitrate and bicarbonate), sulfate caused strong inhibition of arsenic removal, and bicarbonate and nitrate caused weak inhibition due to specific and nonspecific adsorption onto hematite, respectively. In the column experiments, high content of hematite-coated sand enhance the arsenic removal, but the amount of the arsenic removal decreased due to the higher affinity of As(V) than As(III) and reduced adsorption kinetics in the flow system, Therefore, the amount of hematite-coated sand, the adsorption affinity of arsenic species and removal kinetics determined the removal efficiency of arsenic in the flow system. arsenic, hematite-coated sand, permeable reactive barrier, anion competition, adsorption.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
• /
• 2002.09a
• /
• pp.347-350
• /
• 2002

The petrochemical products can cause soil and groundwater contamination during their transportation and the use of the products, and while being contained in underground storage tanks(USTs) throughout the leakage. To treat the contaminated soil, the bioventing method is suitable for the remediation of semi-volatile compounds, such as diesel and kerosene. Biofiltration is one of possible method to treat the off-gas produced in the process of the bioventing. This study is related to the usage, effectiveness of treatment, and feasibility of two types of biofilter system made of ceramic-compost and polymer respectively to treat diesel VOCs at constant retention time of 20 sec. Compost biofilter showed the average removal efficiency of 73 % when the inlet concentration increased to 20 ppmv. Increased the inlet concentration decreased the microbial activities as well as the removal efficiency. On the contrary, the removal efficiency of the polyurethane biofilter was maintained at 88 % at the inlet concentration of 13 ppmv during ten days and was obtained to 80 % at the inlet concentration of 30 ppmv in spite of the drop of the efficiency in the sudden increase of the inlet concentration. At the beginning of the experiment it showed low removal efficiency at low inlet concentration due to the low microbial activity, however, as experiments proceed the removal efficiency could be obtained more than 80% at high inlet concentration.

• Journal of Korean Society of Water and Wastewater
• /
• v.21 no.1
• /
• pp.47-55
• /
• 2007

The waste water treatment facility at rural and mountainous region in catchment areas of dams should be small scale. The wastewater treatment facility of small scale has some specification as follows;1)simple process, 2)low maintenance cost, and 3)high removal efficiency. So, we developed the bioreactor which can be satisfied with the specification of small scale waste water treatment facility. The bioreactor consisted of the anoxic and oxic zone. The two zones were effectively separated by cone type baffle. By the effective separation through CTB, the nitrification and denitrification reaction occurred effectively. Therefore, the removal efficiency of total nitorgen (TN) increased compared to other types of baffle. And, we put into the bio activated media in oxic zone to increase the concentration and activity of microbiology. The media contained the components which were made of many kinds of the minerals to increase the activity of microbiology. Additionally, we observed that the phosphate removal efficiency increased by bio activated media. This is resulted from the coagulation-sedimentation reaction by mineral in components. The average removal efficiencies of TN and TP during Run 2 were 69 and 89% which were 4 and 25% higher than those during Run 1 without the MA, respectively. For BOD, COD, SS and TKN, the average removal efficiencies at Run 2 were slightly higher than those at Run 1. Therefore, we could maintain the high concentration and high activity of microbiology through bioreactor developed in this study. And the removal efficiency of TN and TP increased.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.15 no.5
• /
• pp.3298-3303
• /
• 2014

In order to recycle the waste bumper, techniques removing coated paint on a bumper is crucial. Chemical methods are known to be much more effective in removing the paint compared to physical methods. However, the chemical methods generally use toxic solvents and consequently cause environmental pollution. In this study, we tested a new method which combines the chemical and physical method to reduce the amount of solvent and increase the paint removal efficiency. We found that mechanical stirring increases the paint removal efficiency in soaking stage of solvent. When solid particles as a stress transfer media are incorporated into the solvent and high mechanical stirring is applied, the paint removal efficiency is very high. It was proved that the combined method can accomplish high level of the paint removal efficiency maintaining low amount of solvent consumed.

• Particle and aerosol research
• /
• v.14 no.1
• /
• pp.9-16
• /
• 2018

We have developed an electrostatic precipitation (ESP) type air cleaner for indoor air quality and investigated its performances regarding CADR (Clean air delivery rate), single-pass efficiency and gas removal efficiency. The ESP air cleaner used an ACF (Activated carbon fiber) filter for gas removal and the ACF as a high voltage electrode for particle removal. The ESP air cleaner was tested in a chamber with the volume of $1m^3$ regarding CADR and gas removal efficiency. The applied CADR area of the ESP was $1.8m^2$. Gas removal efficiency was tested with 3 gases (Acetaldehyde, Acetic acid, Ammonia). As the results of the gas removal efficiency, the ESP air cleaner shows the removal efficiencies of 90, 98 and 85% for acetaldehyde, acetic acid and ammonia, respectively.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
• /
• 2000.05a
• /
• pp.121-124
• /
• 2000

In-situ soil remediation using electrokinetics has been investigated and the attempts for the removal of hydrocarbons have been continued. In this study, the electrokinetic remediation using three different kinds of surfactnats was conducted for the removal of phenanthrene from clay The used surfactnats were APG, Brij30 and SDS. In the solubility test for phenanthrene, the experimental result was APG

• Journal of environmental and Sanitary engineering
• /
• v.15 no.2
• /
• pp.41-48
• /
• 2000

In this study, we have investigated the effect of the various operating conditions on the removal fluorine in the rinsed water for the semiconductor industry by using electrolysis process. The removal efficiency of fluorine was irrelevant to initial pH, and carbon anode was high-level treatment in the effect of various electrodes. Fluorine included in the wastewater is treated by the addition of a Ca(OH)2, removal efficiency of electrolysis was increased about 40%. Besides the removal efficiency of fluorine was increased as the current density was increased and this treatment system could reduce both the total sludge and running costs. The feasibility of the electrochemical treatment to the fluorine containing wastewater was verified from this study.

• Journal of Environmental Health Sciences
• /
• v.22 no.4
• /
• pp.1-9
• /
• 1996

Experiments have been made to test the practical feasibility of using calcined manganese ore to desulfurize hot reducing gas. In this study, the effects of particle size of sorbents, temperature of sulfidation, flow rate and sorbent characteristics on the $H_2S$ removal efficiency of calcined manganese ore were investigated. Experimental results showed that the removal efficiency of $H_2S$ was optimum when the temperature was about 800$\circ$C and that the smaller particle size the higher the $H_2S$ removal efficiency. When the temperature was above 800$\circ$C, the reactivity of sorbent has lowered because agglomeration of sorbent increased intraparticle transport resistance, and this phenomenon was confirmed by SEM photographs. As the temperature increases, capacity for the $H_2S$ removal was increased but the equilibrium concentration of $H_2S$ was not affective.