• Journal of Korean Society of Environmental Engineers
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• v.28 no.8
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• pp.878-883
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• 2006

Removal efficiency of As(III) was investigated with a pilot-scale filtration system packed with an equal amount(each 21.5 kg) of manganese-coated sand(MCS) in the bottom and iron-coated sand(ICS) in the top. Height and diameter of the used column was 200 cm and 15 cm, respectively. The As(III) solution was introduced into the bottom of the filtration system with a peristaltic pump at a speed of $5{\times}10^{-3}$ cm/s over 148 days. Breakthrough of total arsenic in the mid-sampling position(end of the MCS bed) and final-sampling position(end of the ICS bed) was started after 18 and 44 days, respectively, and then showed a complete breakthrough after 148 days. Although the breakthrough of total arsenic in the mid-sampling position was started after 18 days, the concentration of As(III) in this effluent was below 50 ppb up to 61 days. This result indicates that MCS has a sufficient oxidizing capacity to As(III) and can oxidize 92 mg of As(III) with 1 kg of MCS up to 61 days. When a complete breakthrough of total arsenic occurred, the removed total arsenic by MCS was calculated as 79.0 mg with 1 kg MCS. As variation of head loss is small at each sampling position over the entire reaction time, it was possible to operate the filtration system with ICS and MCS for a long time without a significant head loss.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.3
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• pp.475-484
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• 2000

The purpose of this study was to develop model for estimating biodegrability of organic sludge (sewage and papermill) in various environmental conditions. to assume degradable degree with operating time of SRB reactor. and evaluate duratior of organic sludge as carbon source. Average TCOD was 28.7~63.2mg/L in effluent. organic sludge did not much supply carbon source for experimental period. But in point of durability. it seemed that organic sludge was efficient because it was not consumed by degradation of much organic matter within short period. With increasing $SO_4{^{2-}}$ reduction rate. Pb and Fe was removed 77~82% and 33~59%. respectively. Because Al was precipitated as a hydroxide. its removal rate wa,. about $54{\pm}2%$ in R-l~R-3 maintaining low pH but about 78% in R-4 maintaining high pH. Because Mn was large in solubility. it showed to be much lower than other heavy metals. Considering supportable capacity or durability of orgainc matter for initial SRB mixing ratio of sewage/papermill 0.5 was regarded as appropriate substituting material and at this time. it estimated that carbon source continued about 3.08 year but safety factor must apply to be thought over. because various factors had an effect on degradation of organic sludge.

• Journal of Korean Society of Environmental Engineers
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• v.36 no.7
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• pp.483-491
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• 2014

In this study, we developed an M-COS (molit coagulant-dosing optimization system), which enables to apply the optimum coagulant dose determined in real time, in order to satisfy the total phosphorus (TP) regulation (0.5 mg/L), and then tested its field applicability. Field tests were conducted at three different periods in 2014 in a pilot plant where the M-COS was installed. Coagulant reduction rate by the M-COS was 10.4%, 15.3%, and 9.0% for each period (average 11.6%), when comparing with a control where coagulants were applied at a constant rate. Total cost for the M-COS or control was estimated by summing up the coagulant cost and sludge treatment cost, and then the resulting cost increase was predicted. Cost reduction rate by the M-COS was 13.8%, 20.0%, and 11.4% for each period (average 15.0%). This study indicates that the M-COS can be an alternative to a conventional system for TP treatment, with a better cost efficiency.

• Microbiology and Biotechnology Letters
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• v.39 no.2
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• pp.161-167
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• 2011

We previously showed that five strains belonging to Pseudomonas could remove TPH (Total Petroleum Hydrocarbons) efficiently when they are applied to TPH-contaminated soil. We optimized the bioremediation condition using different hydrocarbons and nutrients conditions to improve the efficiency. We setup lab-scale column bioreactor to monitor TPH and diesel removal efficiency. When we applied five Pseudomonas sp. mixtures to 25,000 $mg{\cdot}kg^{-1}$ TPH-contaminated soil (diesel 10,000 $mg{\cdot}kg^{-1}$, kerosene 10,000 $mg{\cdot}kg^{-1}$, gasoline 5,000 $mg{\cdot}kg^{-1}$) with the optimum condition, 76.3% of TPH removal efficiency was shown for 25 days. Meanwhile, in the application of five Pseudomonas sp. mixtures to 20,000 $mg{\cdot}kg^{-1}$ diesel-contaminated soil with the optimum condition, 99.2% of diesel removal efficiency was shown for 40 days. In the application to lab-scale bioreactor with five high efficiency bacteria, 88.5% of TPH removal efficiency was shown for 45 days. Based on the results from this study, we confirmed that this mixed Pseudomonas sp. consortium might improve the bioremediation of TPH in contaminated soil, the efficacy can be controlled by improving the nutrients. We also confirmed that the nutrients and oxygen for biodegradation of TPH could contribute on the management and control of applications of these strains for the study of bioremediation of TPH-contaminated soil.

• Journal of Korean Society of Environmental Engineers
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• v.34 no.11
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• pp.780-785
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• 2012

Existing states of attached algae in the sedimentation basin was observed during late april to early october, and the attached algae were visible 7 days after of cleaning the trough and the communities of algae became larger with increasing the operation periods. Attached algae community included bluegreen algae (Oscillatoria sp.), diatom (Synedra sp.,) and green algae (Mougeotia sp., Oedogonium sp.) and suspended diatom (Stephanodiscus sp.) as well. Diatom (Cymbella sp., Navicula sp., Synedra sp. and Stephanodiscus sp.), green algae(Mougeotia sp. and Cosmarium sp.) and blue-green algae (Anabaena sp.) were detected in the effluent of sedimentation basin. The chlorophyll-a (chl-a)concentrations of algae community on a square centimeter after 14 and 28 days were distinctively different depended on the copper sulphate treatment. The concentration of chl-a were $4{\mu}g/L/cm^2$ and $19{\mu}g/L/cm^2$ for the copper sulphate treated water and $59{\mu}g/L/cm^2$ and $147{\mu}g/L/cm^2$ for the untreated water. Diatom algae fragments were observed in red-brownish sediments on the bottom of industrial water distribution basin and degraded blue-green and green algae formated organic sediments combined with oxidized iron.

• Journal of Korean Society of Environmental Engineers
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• v.30 no.1
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• pp.31-36
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• 2008

This work was performed to evaluate the effect of membrane material and structure on fouling in a submerged membrane bioreactor(MBR). Three types of microfiltration membranes with the same pore size of 0.1 $\mu$m but different materials, polytetrafluoroethylene (PTFE), polycarbonate(PCTE) and polyester(PETE), were used. While PETE membrane exhibited the most rapid flux decline throughout the operation, PCTE and PTFE had a similar tendency with regard to permeability. Difference in permeability between PETE and the other membranes gradually decreased with time, which was probably due to chemical cleaning. The higher TOC rejection of PETE membrane could be attributable to its faster fouling, resulting from a larger amount of foulants to get attached to the membrane in a shorter time. DOC fractionation using a DAX-8 resin showed that the composition of each fraction between the supernatant and permeates did not change significantly with operation time, indicating that membrane hydrophilicity/hydrophobicity was not a dominant factor affecting to MBR fouling in this study. Compared to other membranes, the fouling of PETE membrane was more influenced by pore clogging (irreversible fouling), which would probably contribute to a higher organic rejection of the PETE membrane.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.5
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• pp.700-707
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• 2017

In the international natural gas market, natural gas has markedly low calories. The domestic calories standard of natural gas was changed and the performance and efficiency of many industrial machines using natural gas were affected because of low caloric natural gas. Therefore, in this study, a dual fuel engine fueled with natural gas and diesel was tested to examine the effects of the CNG substitution rate on the combustion characteristics, such as thermal efficiency, COVimep and heat release rate. The CNG substitution rate was defined as the ratio of CNG instead of diesel, which was calculated as the total energy. The conditions of the tested engine were fixed $1800rpm/500N{\cdot}m$. In addition, diesel fuel was injected at $16^{\circ}CA$ BTDC and the fuel pressure was fixed at 85 MPa; the lower heating value of CNG was $10,400kcal/Nm^3$. The results of the engine test showed that the amount of diesel fuel was changed according to the CNG substitution rate. Therefore, when the substitution rate was increased, the amount of diesel fuel was decreased, which affected the energy for ignition. In addition, the ignition delay duration was increased, which affected the thermal efficiency and torque. On the other hand, the COVimep was less than 5% and a stable combustion state of the engine was shown.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2001.09a
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• pp.164-167
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• 2001

본 연구에서는 포항제철소에서 제철부산물로 발생되는 제강분진을 전처리 없이 산화촉매로 사용하여 김포 수도권 매립지의 침출수 처리공정에서 펜톤산화조에 유입되는 원수를 대상으 로 과산화수소를 이용한 연속식 산화처리 실험을 수행하였다. 먼저 회분식 실험결과를 바탕 으로 최적 반응조건에서 lab-scale 연속식 기초반응실험과 자체 설계.제작한 연속산화공정에서의 처리실험을 수행하였다. 또한 기존의 펜톤산화공정에서 Fe 공급원으로 사용되고 있는 FeSO$_4$.7($H_2O$)와의 반응성 비교실험도 수행하였다. 반응기간동안 일정 pH를 유지하기 위해 pH controller를 사용하였으며 침출수 수질은 CODcr로 나타내었다. 반응 pH 3.5, 체류시간 1 hr, 과산화수소 주입량 1,500mg/1에서 제강분진과 FeSO$_4$.7($H_2O$)를 각각 주입하여 수행한 연속처리 기초실험에서는 제강분진을 산화반응촉매로 사용한 경우에 침출수CODcr 처리율 62%, 과산화수소의 분해율 52%를 나타내었다. FeSO$_4$.7($H_2O$)를 산화반응 촉매로 사용한 경우에는 약 65-70%정도의 다소 높은 처리효율을 나타낸 반면에 과산화수소의 소비량은 제강분진의 경우보다 약 20%이상의 높은 값을 나타내었다. 연속산화공정 실험에서는 운전 3시간 이후에 유출수 중의 CODcr과 $H_2O$$_2$의 농도가 안정된 값을 나타내었다. 이 때 산화 반응조의 침출수 CODcr 제거효율은 약 43%이었으며, 처리수의 농도는 현재의 침출수 방류기준 이하로 나타났다. 결론적으로 침출수의 연속식 산화처리 실험결과, 처리효율과 경제성에서 제강분진의 산화촉매활용 공정의 개발 가능성이 매우 높은 것으로 나타났다.ell에 의해 완전분해 되었으며, 함께 존재시 TC는 Fe$^{\circ}$만으로는 분해가 되지 않았지만 cell에 의해 완전분해 되었으며, 함께 존재시 TCE분해에 저해작용을 미치는 것으로 나타났다.술의 첨가가 요구되고 있다. 따라서, 산성광산배수 오염지대에 대해 획일적으로 같은 처리방법을 채택하여 사용하는 것보다 각 지역 또는 광산산성폐수가 유출되어 나오는 광산폐기물의 특성 등을 고려하여 거기에 맞는 기술들을 복합적으로 또는 단독으로 사용하되 처리방법 채택 시 신중을 기할 것이 요망된다.정시에는 SeaWiFS 위성과 관련된 global algorithms 중에서 490nm와 555nm의 복합밴드를 포함하는 OC2 알고리즘(ocean color chlorophyll 2 algorithm)을 사용하는 것이 OC2 series 및 OC4 알고리즘보다 좋은 추정 값을 도출할 수 있을 것으로 기대된다.환경에서는 5일에서 7월에 주로 이 충체의 유충이 발육되고 전파되는 것으로 추측되었다.러 가지 방법들을 적극 적용하여 금후 검토해볼 필요가 있을 것이다.잡은 전혀 삭과가 형성되지 않았다. 이 결과는 종간 교잡종을 자방친으로 하고 그 자방친의 화분친을 사용할 때만 교잡이 이루어지고 있음을 나타내고 있다. 따라서 여교잡을 통한 종간잡종 품종육성 활용방안을 금후 적극 확대 검토해야 할 것이다하였다.함을 보이고 있다.X> , ZnCl$_{3}$$^{-}$같은 이온과 MgCl$^{+}$, MgCl$_{2}$같은 이온종을 형성하기 때문인것 같다. 한편 어떠한 용리액에서던지 NH$_{4}$$^{+}$의 경우 Dv값이 제일 작았다. 바. 본 연구의 목적중의 하나인 인체유해 중금속이온인 Hg(II), Cd(II)등이 NaCl같은 염화물

• Proceedings of the Korea Water Resources Association Conference
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• 2008.05a
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• pp.495-499
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• 2008

This study developed a determination method for a rainwater retention-pumping combination system for roof runoff control. The outflow and stored water volume in the rainwater system was simulated using a water balance equation. Its result is presented in the TPP (Tank capcity-Peak outflow-Pumping rate) curves for rainfall return periods. In a case study on reduction of the peak flow rate of 100-year return period to 5-year in Seoul, The range of pumping rate for $100m^2$ roof area is determined as $0{\sim}25{\ell}$/min. Additionally, retention volume of $8.5{\sim}10m^3$ can be combined with the pumping rate range. That is to say an effective combination of a retention-pumping system capacity can be determined from a system of $8.5m^3$ tank with $25{\ell}$/min to $10m^3$ tank without pump. Using the TPP curves, engineers can determine the effective combination range of retention & pumping system capacity. Furthermore, that can be helpful to decide a detail system capacity for field condition.

• Journal of the Korea Organic Resources Recycling Association
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• v.12 no.3
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• pp.76-85
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• 2004

Anaerobic decomposition of municipal solid waste (MSW) had potential adverse impacts such as the production of methane and long-term post closure on human health and the environment. It was demonstrated that aerobic degradation of MSW resulted in the reduction of a methane yield and the enhancement of stabilization of MSW. Excavated solid wastes were both aerobically and anaerobically treated in order to evaluate the effects of air injection on the stabilization of landfill site. The municipal solid waste (MSW) samples were excavated from a 10-year old landfill (operation period: 1991. 11~1994. 11), Jeonju, Korea. Excavated municipal solid wastes are primarily composed of soils and vinyl/plastics. For the two aerobic simulated lysimeters, the levels of $O_2$ ranged 1.6~23.1% and the levels of $CO_2$ ranged 1.5~15.1%, which confirmed the aerobic decomposition. Aeration did prevent methane formation. For the anaerobic simulated lysimeter, the $CO_2$ rose as $O_2$ was consumed and low levels of CH4 were produced. The pH levels ranged from 7.7 to 8.9 for anaerobic lysimeter and from 7.3 to 8.5 for aerobic lysimeters. As expected, aerobic treatment proved to enhance the removal of biodegradable materials in the excavated solid wastes when monitoring the concentration of BOD, COD, $NH_4-N$, and $NO_3-N$ in the leachate.