• Journal of Korean Society on Water Environment
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• v.24 no.4
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• pp.436-441
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• 2008

This work experimentally determined the effect of operating parameters such as temperature and solid retention time (SRT) on the phosphorus removal of municipal wastewater with waste-tire media. The experiments were carried out in pilot-scale moving bed biofilm reactor filled at a 0.15 filling ratio with the media. Total phosphorus (TP) removal efficiency was $91{\pm}5$, $75{\pm}16$, and $59{\pm}14%$ at the temperature of 9~10, 10~20, and $20{\sim}26^{\circ}C$, respectively. TP removal efficiency was $71{\pm}17$, $74{\pm}16$, $74{\pm}16$, and $68{\pm}18%$ at the SRT of 3.5~5, 5~10, 10~15, and 15~20 days, respectively. At the nitrate concentration of 1~3, 3~6, and 6~9 mg/L, TP removal efficiency was $82{\pm}9$, $68{\pm}18$, $47{\pm}7%$, respectively. The concentration of total phosphorus in the effluent was $0.1{\sim}1.8(0.8{\pm}0.4)mg/L$ regardless of operating conditions, which meets Korean phosphorus limit value, 2 mg/L, for discharge into receiving waters.

• Journal of Environmental Science International
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• v.10 no.1
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• pp.59-64
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• 2001

The effect of major operating parameters in spray drying sorber(=SDS) for automatic control for the simultaneous removal of acidic and organic gaseous pollutants from solid waste incinerator was performed. The field experiment was carried out in pilot scale test for the quantification of major operating parameters of hydrophilic and the hydrophobic pollutants. The removal efficiencies of $SO_2$and HCI in the 5wt% slurry condition were being increased with the increase of the stoichiometric ration which is the molecular ratio of lime to the pollutant concentration, and with the decrease of inflow flue gas temperature in the pilot SDS reactor. The removal efficiency along the height of spray drying sorber was closely related to the temperature profile, and more than 90% of total removal efficiency was achieved in an absorption region. For the removal of acidic gas the optimum operating condition considering the economics and a stable operation is the 5wt% of slurry concentration, 1.2 of stoichiometric ratio and 25$0^{\circ}C$ of inflow flue gas temperature. For the organic gases of benzene and toluene the removal efficiencies were 20-60% which is much lower than that of acidic gas. The best removal efficiency was obtained at 1.5 of stoichiometric ratio and 25$0^{\circ}C$ of inflow flue gas temperature. The organic\`s removal efficiency along the height of spray drying sorber was quite different from that of acidic gas, that is, more than 60% of the total removal efficiency for benzene and 90% of the total removal for toluene were achieved in the dried adsorption region, which was formed at the lower or exit part of the reactor.

• 한국신재생에너지학회:학술대회논문집
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• 2007.06a
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• pp.804-807
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• 2007

The acid gas removal (AGR) system was designed and installed to remove $H_2S$ in coal syngas in the pilot-scale coal gasification system for producing chemicals like Dimethyl Ether(DME). The syngas from the coal gasification at the rate of $100{\sim120$ $Nm^3$/hr included pollutants such as fly ash. $H_2S$, COS, $NH_3$, etc. The designed temperature and pressure of the AGR system are below 50oC and 8 kg/$cm^2$. Fe-chelate was used as an absorbent. $H_2S$ was stably removed below 0.5 ppm in the AGR system when the concentration of $H_2S$ was $150{\sim}450$ ppm. The pH of Fe-chelate solution was also stably maintained between $8{\sim}9$. FeMgO absorbent was also tested to remove $H_2S$ in the lab-scale AGR system and $H_2S$ was also removed below 0.5 ppm in the initial operation.

• Progress in Superconductivity and Cryogenics
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• v.22 no.2
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• pp.12-16
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• 2020

Circulating cooling systems consume a lot of water, and most of the water from river, which contains a large amount of Ca2+, Mg2+, et al, and has the characteristics of high hardness and large turbidity. The water can form scale on the surface of the heat exchanger and the pipes, which would reduce the heat transfer efficiency and affect the heat exchanger's length of service. In this study, the Superconducting High Gradient Magnetic Separation (S-HGMS) technology was used in river water treatment and the effects of agent A, agent B, and S-HGMS on the removal of hardness and turbidity were discussed. The results showed that the hardness removal rate reached 71.3% and the turbidity was decreased to 0.5 NTU.

• Journal of Korean Society of Water and Wastewater
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• v.22 no.3
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• pp.323-328
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• 2008

During the full-scale water treatment operation at "G" Water Treatment Plant in Seoul, we investigated changes in pore volume distribution and specific surface area of GAC with time. The pore volume of the used GAC decreased to the level below 0.6 cc/g while that of the brand new GAC was ranged 0.7~0.9 cc/g. The specific surface area of GAC pores changed within the range between $1100{\sim}1200m^2/g$ and $700{\sim}800m^2/g$. Bacteria attached to the surface of GAC shows a gradual increase ($0.4{\time}10^6{\sim}8.5{\time}10^6CFU/g$) under scanninig electron microscope (SEM). TOC removal was enhanced due to growth of the attached bacteria on GAC. It was found that TOC removal was closely related with physical parameters (pore volume, specific surface area) linearly under the investigated conditions. The used GAC need to be exchanged into new one or re-generated to remove organic matters (TOC) effectively from the finished drinking water.

• Journal of the Korean Society for Precision Engineering
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• v.19 no.1
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• pp.196-203
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• 2002

Generally, non-uniformity and removal rate are important factors on measurements of both wafer and die scale. In this study, we verify the effects of the pressure and relative velocity on the results of the chemical mechanical polishing and the effect of pattern density on inter layer dielectric chemical mechanical polishing of patterned wafer. We suggest an appropriate modeling equation, transformed from Preston\`s equations which was used in glass polishing, and simulate the removal rate of patterned wafer in chemical mechanical polishing. Results indicate that the pressure and relative velocity are dominant factors for the chemical mechanical polishing and pattern density effects on removal rate of pattern wafers in die scale. The modeling is well agreed to middle and low density structures of the die. Actually, the die used in Fab. was designed to have an appropriate density, therefore the modeling will be suitable for estimating the results of ILD CMP.

• Journal of Korean Society of Water and Wastewater
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• v.20 no.2
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• pp.289-294
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• 2006

A pilot scale non-woven fabric filter separation activated sludge system was investigated for practical application on domestic wastewater reclamation and reuse. The system was operated in A/O (Anaerobic/Oxic) process with submerged filter module in the aerobic compartment. In the test of two types of filter materials ($70g/m^2$ and $35g/m^2$), the initial flux (0.42m/d) could be maintained for about three months by regular air backwashing of $70g/m^2$ filter at 0.3m water head. The removal efficiency of organic matter by the system was BOD 93.3%, CODcr 96.3%, SS 96.7%. The effluent quality was 7.8mg/L, 12mg/L and 5mg/L for BOD, CODcr and SS, respectively. The water quality was enough to meet a standard for domestic reuse without human contact. T-N removal efficiency was 49.9% at internal recycle rate 2Q and C/N ratio 3.3. The removal efficiency of T-P was 50% with average effluent concentration, 2.6mg/L.

• Journal of Korean Society of Water and Wastewater
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• v.20 no.2
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• pp.273-280
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• 2006

The sludge settleability is a key factor for operating activated sludge process as well as BNR (biological nutrient removal) process, because the poor sludge settling causes an increase of suspended solid in the effluent. In order to improving the sludge settleability, a settling agent such as iron dust can be applied. In this study, the effect of sludge settleability on the performance of DNR (Daewoo nutrient removal) process was investigated with GPS-X, which is the popular wastewater treatment process model program, and the result of modeling was verified with operating lab-scale DNR process. As a result, if the sludge blanket keeps stable in the secondary settling tank, the effluent quality is similar in spite of different SVI values. And in case of the good sludge settleability, short HRT or long SRT increased the biomass concentration in the bioreactor, and improved the pollutant removal efficiency. In spite of daily influent changing, the good sludge settleability also guaranteed the stable effluent quality. And the results of the lab-scale DNR process experiment could support the simulated results.

• Journal of Korean Society on Water Environment
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• v.20 no.3
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• pp.269-274
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• 2004

The performance of a newly designed wastewater treatment process equipped with an anaerobic and two intermittent aeration tanks operated alternately was investigated. During the experimental period, several types of cyclic operating schedules with different aeration and non aeration time were examined for the optimization. At all modes, the removals of organic matter and SS were highly achieved. With respect to T-N removal, however, the cycle length for aeration on/off affected the efficiencies. At the optimal operating mode, the ORP bending point indicating the disappearance of nitrate was observed. Considering the influent wastewater characteristics and cyclic operating schedules, it can be suggested that T-P removal is much more BOD/T-P ratio and/or its load dependant rather than the aeration on/off time. The results obtained from pilot-scale test showed the competitive advantage of this alternating process through an omission of nitrate recycle and operational flexibility against influent load variations when comparing with other continuous flow processes.

• Journal of Environmental Science International
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• v.12 no.7
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• pp.791-799
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• 2003

This study was carried out to get more operational characteristics of the sequencing batch biofilm reactors with media volume/reactor volume ratio of 15 %, 25 % and 35 %. Experiments were conducted to find the effects of the media packing ratio on organic matters and nutrients removal. Three laboratory scale reactors were fed with synthetic wastewater. During studies, the operation mode was fixed. The organic removal efficiency didn't show large difference among three reactor of different packing media ratios. However, from the study results, the optimum packing media ratios for biological nutrient removal was shown as 25%. The denitrifying PAOs could take up and store phosphate using nitrate as electron acceptor.