• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.190.1-190.1
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• 2016

One of the most serious problems faced by billions of people today is the availability of fresh water. According to statistics, 15% of the world's total output of dye products is discharged into the environment as dye wastewater, which seriously pollutes groundwater resources. For the treatment of chemically and biologically contaminated water the advanced oxidation processes (AOPs) shows the promising action. The main advantage with AOPs is the ability to degrade the organic pollutants to $CO_2$ and $H_2O$. For this degradation process the AOPs generation of powerful and non-selective radicals that may oxidize majority of the organic pollutants present in the water body. To generate the various reactive chemical species such as radicals (${\bullet}OH$, ${\bullet}H$, ${\bullet}O$, ${\bullet}HO_2$) and molecular species ($H_2O_2$, $H_2$, $O_2$) in large amount in water, we have used the atmospheric pressure plasma. Among the reactive and non-reactive species, the hydroxyl radical (${\bullet}OH$) plays important role due to its higher oxidation potential (E0: 2.8 V). Therefore, in this work we have checked the degradation of various dyes such as methyl orange, methylene blue and congo red using different type of atmospheric pressure plasma sources (Indirect jet and direct jet). To check the degradation we have used the UV-visible spectroscopy, HPLC and LC-MS spectroscopy. Further, to estimate role of ${\bullet}OH$ on the degradation of dyes we have studied the molecular dynamic simulation.

• 유기물자원화
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• 제4권1호
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• pp.53-60
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• 1996

혐기적으로 1차 분해된 하수슬러지를 건물 중 기준으로 0, 1, 3, 그리고 5톤/10a 비율로 포장에 시용한 후, 대두 및 당근의 수량과 무기성분 흡수 등 몇가지 화학적 특성에 미치는 영향을 검토하였다. 슬러지 시용의 결과는 토양의 몇가지 화학적 특성을 증진시킨 반면, 작물에서의 Pb, Cd, Cr, As 및 Hg과 같은 유해 중금속의 흡수는 나타나지 않았다. 슬러지 시용은 작물의 N, P, K 및 Ca 등의 무기성분 흡수를 증가시켰고, 슬러지중 과량의 Al은 작물의 Al흡수에 별다른 영향을 주지 않았다. 또한 슬러지는 두 작물의 수량을 증가시킨 반면, 슬러지 미부숙으로 인해 당근의 외관적 품질을 저하시켰다. 결론적으로 하수슬러지의 작물 생육효과가 긍정적으로 평가된 반면, 농업적으로 이용할 때는 반드시 퇴비화와 같은 슬러지의 안정화가 선행되어야 한다.

• 공업화학
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• 제7권2호
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• pp.371-378
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• 1996

경기도 광주군 소재 경안천 하 폐수 종말처리장을 실제 적용 대상으로하여 공정 조업상에 발생될 수 있는 문제점의 원인을 진단 및 분석하고 이에 적절한 대응 방안을 제시할 수 있는 조업지원 목적의 prototype의 전문가 시스템을 연구, 개발하여 실제 적용 test를 수행하였다. 특히 생물학적 폐수처리 공정인 폭기조와 최종 침전지상에서 발생될 수 있는 공정상의 문제점을 집중분석 (bulking 현상 등) 하여 100 여개의 production-rules로 구성된 지식베이스를 완성하므로써 공정의 안정적인 조업관리 및 유지가 가능하도록 하였고 조업에 있어서 전문 및 표준기술을 제공하므로써 특히 경험이 부족한 신입 현장 조업자들의 조업능률을 향상시킬 수 있었다. 향후의 과제는 조업 data를 통계처리하여 공정조업에 영향을 미치는 인자와 조업 제어변수간에 상관관계를 분석하고 최적의 조업조건을 제시할 수 있는 통계제어모델을 개발하여 전문가 시스템에 접목시킴으로써 Prototype이 아닌 완벽한 공정시스템 도구로 발전시키고자 한다.

• 한국물환경학회지
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• 제21권5호
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• pp.458-463
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• 2005

Considering the characteristics of a filtration bio-reactor equipped with a mesh filter module which can effectively maintain high concentration of biomass and enhanced solid-liquid separation performance, the hybrid process of filtration bio-reactor combined with coagulation was investigated to get improved filtration characteristics as well as water quality in this work. Two bio-reactors (Run-1 & Run-2) were operated under the following conditions: working volume of 25 L, continuous loading of a synthetic wastewater (BOD: 200 mg/L, T-N: 50 mg/L, T-P: 5 mg/L), where an appropriate amount of alum ($Al_2(SO_4)_3{\cdot}18H_2O$) was added once a day into the reactor (Run-2). In the system without using a alum (Run-1), the clogging of mesh filter module was observed two times through 85 days of whole operation. Meanwhile, the filter module did not clog even at higher MLSS concentration (6,000~12,000 mg/L) and the stable filtration (0.7 mid) was continued in the case of using a alum. Due to the stable formation of cake layers, BOD and SS were shown below 6 and 3 mg/L, respectively. T-P and pH of the effluent were changed because of the intermittent addition of the alum. In the case of Al/P=2.5, the average T-P removal efficiency per day was 85.2% and the average T-P concentration of the effluent was 0.3 mg/L. However, the removal efficiency of phosphate was influenced by pH in the reactor.

• 한국물환경학회지
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• 제23권5호
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• pp.766-775
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• 2007

The use of toxic chemicals was extended as the industry in Korea has grown dramatically during the last three decades. However, list of toxic substances and limit concentrations in the water environment are not consistent within management of ambient water, drinking water and industrial effluent. This article suggests the systematic framework to classify toxic substances in the water environment and deriving their effluent limits. The most important factor for decision-making to classify toxic substances is whether their concentrations in the water environment are higher than the reference concentrations, estimated by considering human health risk and ecological risk. Using a risk-based reference concentration, the ambient water quality criterion, it is possible to derive the regulatory limit concentrations of toxic substances in drinking water and in industrial effluent. The goal concentrations in the effluent, which guarantee the human and ecological safety, should be determined with scientific investigation, balancing environmental benefit and economical effect, considering availability of treatment technology and identifying characteristics of wastewater from different industries.

• 한국물환경학회지
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• 제25권3호
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• pp.386-393
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• 2009

This study was carried out to assess water quality and to introduce the management measures for water quality improvement with the collected data from 87 agricultural reservoirs in Han river watershed. According to the water quality criteria (WQC) for lake based on the COD, TP, TN and chl.a concentration, 18, 16, 4 and 19 of 87 reservoirs exceed class IV, respectively. Based on the trophic state index (TSI) with chl.a concentration, 51 of selected reservoirs appeared to be eutrophic. Phosphorus was limiting nutrient on algal growth in 58 reservoirs. TP, chl.a and COD concentration in 23 of 49 agricultural reservoirs with chl.a concentration ${\geq}25{\mu}g/L$ and eutrophic exceed class IV by WQC. Also, the mean depth in 21 of 23 reservoirs was below 5m. Our results suggest that advanced wastewater treatment and crop land control in watershed of reservoirs with TP concentration ${\geq}0.1mg/L$ would be a effective tool to improve water quality. Dredging would to be effective measure in reservoirs with mean depth < 5 m and relatively old age. In reservoirs with chl.a concentration ${\geq}50{\mu}g/L$, application of technique such dissolved air flotation (DAF) and P inactivation be effective to improve water quality by removing particulate matters in water column. The management measure to control inflow such as sedimentation basin, Pre-dam and diversion would to be application in reservoirs with shallow depth, while large watershed and surface area.

• Advances in environmental research
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• 제5권3호
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• pp.189-200
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• 2016

This study aimed at advanced oxidation of hetero tri-functional reactive dye Acid orange 7 using photo-Fenton conditions in a lab-scale experiment. Decolourisation of Acid Orange 7 dye by Fenton's process was dependent on concentration of Hydrogen peroxide, Ferrous sulphate, pH, and contact time. A $2^3$ factorial design was used to evaluate the effects of these key factors: pH, Fe(II), and $H_2O_2$ concentration, for a dye concentration of 50 mg/L with COD of 340 mg/L at pH 3.0. The response function was removal of colour under optimised conditions; pH 3.0, [Fe(II)] 40.83 mg/L, [$H_2O_2$] 4.97 mmol/L; 13.6 min. of treatment resulting in 100% colour removal. The final COD of treated wastewater was nil suggesting that AOP is a potentially useful process of color removal and dye degradation/mineralisation of effluent having AO7. Minimum contact time for complete decolourisation was at 5 mmol/l $H_2O_2$ concentration. Increase in $FeSO_4$ (mg/l) concentration resulted in decrease of time for complete decolourisation. Box-Behnken Design was used to optimize the process variables. Maximum and minimum levels of pH (3-5), $H_2O_2$ (4-6 mmol/l), $FeSO_4$ (30-46 mg/l) and contact time (5-15 minutes) were used. The statistical analysis revealed a value of 0.88 for coefficient of regression ($R^2$) indicating a good fit of model. Calculated F-value was found higher than the tabulated value confirming to significance of the model. Based on student's t-test, Ferrous sulphate, pH, and contact time have a positive effect on the percent decolourisation of Acid Orange 7.

• 전기화학회지
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• 제16권3호
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• pp.123-128
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• 2013

유기물 첨가에 따른 CDI 모듈셀의 N, P 제거 특성을 위해 2000 ppm $NH_3$, $H_3PO_4$에 methanol, ethanol, iso-propanol, methoxy ethanol, glucose을 1, 2, 3 vol.%를 첨가해 용량 및 이온의 흡 탈착능을 관찰하였다. $NH_3$에서는 탄소수가 증가할수록 용량은 감소하는 경향을 나타내었으며, 용량은 methanol 3 vol.% 첨가 될 때 유기탄소 간섭 전보다 흡착은 16.4%, 탈착은 30.4%의 질소 제거율 증가를 나타내었다. $H_3PO_4$에서는 iso-propanol 2 vol.% 첨가 시에 유기탄소 간섭 전보다 흡착은 63%, 탈착은 54.7% 인산염의 제거율 증가를 확인하였다. 따라서 본 연구에서는 폐수 내의 유기물을 제거하지 않고 N, P 제거 효과와 운영비용을 감소할 수 있는 결과를 나타내었다.

• 한국물환경학회지
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• 제37권6호
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• pp.449-457
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• 2021

Photosynthesis and respiration rate of microalgae are important factors during advanced wastewater treatment research using microalgae, There are several equipments and measurement methods for measuring photosynthesis and respiration, with different challenges that occur during pretreatment and stabilization of the analysis process. Therefore, in this study, for accurate Photosynthesis and Respiration (P&R) analyzer measurement, the analysis process was divided into pre-processing, DO stabilization, and analysis stages and each was optimized to enable accurate evaluation. For this purpose, the effect of DO saturation of the sample on P&R analysis, DO stabilization according to the degassing flow rate, and photoinhibition of the OD level on photosynthesis was investigated. Based on our study results, when DO was supersaturated, photosynthetic efficiency decreased due to photorespiration, making it inappropriate as a P&R sample. In addition, 0.5 L-N2/min level was the optimal nitrogen degassing flow rate for DO desaturation. The inhibition of photosynthetic efficiency by self-shading caused by the increase in OD was observed from OD 2.0, and it was found that P& R analysis is preferably performed on samples with OD less than 2.0. In addition, based on the above three optimization results, an optimized P&R Analyzer instruction for accurate P&R analysis was also presented.

• 한국물환경학회지
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• 제39권2호
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• pp.175-180
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• 2023

The aim of this study was to compare the fouling characteristics of Extracellular polymeric substances (EPS) secreted by Chlorella vulgaris with the case of Bacterial-MBR (BMBR), Microalgal-MBR (MMBR) for advanced wastewater treatment using the Laboratory scale, in order to suggest a method to minimize fouling in MMBR by identifying the effects of amounts and compositions of EPS secreted by C. vulgaris and bacteria in the activated sludge on fouling. Contrary to expectations, fouling occurred relatively severely in the MMBR from the beginning of the operation than in the BMBR. Reasons for such a fouling pattern were considered to be the effect of C-EPS, which accumulates on the membrane surface of MMBR 30 times more than that on the membrane surface of activated sludge (BMBR). In this respect, according to the results of this experiment and a comparative review of several previous studies, it was confirmed that unlike activated sludge, in which the ratio of P-EPS was relatively higher than that of C-EPS, in case of C. vulgaris, the ratio of C-EPS to P-EPS was relatively higher than that in case of activated sludge. This was presumed to be the main cause of the significant fouling phenomenon in MMBR. However, an increase in TMP with increasing C-EPS concentration was not observed.