• 한국물환경학회지
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• 제22권1호
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• pp.91-96
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• 2006

Many small scale Sewage Treatment Plants (STPs) are currently being constructed at many rural areas. The STPs in rural area suffer from low concentration and large inflow quantity fluctuation during wet weather mainly due to illicit combined sewer system. Sequencing Batch Reactor (SBR) is a process effectively coping with these obstacles. The main objective of this study was to evaluate SBR with high hydraulic loading and low inflow concentration. The operating conditions tested were: organic loading rate = $0.17-0.42KgBOD/m^3/d$, hydraulic loadings = $12.1-61.5m^3/m^2/d$, average MLSS concentration = 2500 mg/L, F/M ratio = 0.026-0.17 KgBOD/Kg MLSS, HRT = 9-12 hr HRT, and SRT = 5.6-33.6 days. Organic loading rate on SBR did not impact significantly on BOD and SS removal efficiencies. To increase treatment efficiencies, low hydraulic loading rate with low concentration was required. The results suggested that low influent concentration with high inflow rates during wet weather requires extended time for settling.

• Environmental Engineering Research
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• 제17권2호
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• pp.59-63
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• 2012

This paper proposes a modified Ludzack-Ettinger (MLE) type membrane bioreactor (MBR) as a method of treatment for wastewater from food waste disposer. Micro-membrane filtration allows for an extremely low concentration of suspended solids in the effluent. The effluent of the reactor in question is characterized by a relatively high level of non-biodegradable organics, containing a substantial amount of soluble microbial products and biomass. Results obtained in this paper by measurement of membrane fouling are consistent with biomass concentration in the reactor, as opposed to chemical oxygen demand (COD). The MLE process is shown to be effective for the treatment of wastewater with a high COD/N ratio of 20, resulting in are markedly high total nitrogen removal efficiency. Denitrification could be improved at a higher internal recycle ratio. Despite the low concentration of influent phosphorus, the phosphorus concentration of the outflow is seen to be relatively high. This is because outflow phosphorous concentration is related to COD consumption, and the process operates at along solids retention time.

• Food Science and Biotechnology
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• 제17권4호
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• pp.842-845
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• 2008

This study was carried out to investigate the bactericidal efficacy of concentration (0.1, 0.2, and 0.4 ppm) and exposure time (10 and 30 min) of ozone on bacterial reduction rate of Salmonella typhimurium KCTC 2541 and Staphylococcus aureus ATCC 13515 in the distilled water (DW), and DW supplemented with 0.2% soluble starch (SS), and metal ion (MC) using argentums (Ag) and copper (Cu). The significant bactericidal differences of S. aureus were showed in the treatments of DW and SS, respectively, at the concentration of ozone above 0.1 ppm for 10 min, comparing the respective initial bacterial counts. The bacterial reduction of S. aureus was more sensitive than that of S. typhimurum at the same concentration of ozone. The bacterial reduction rate of SS treatment was slightly lower than that of DW treatment at the same concentration of ozone (p<0.05), however, the bacterial reduction rate of strains improved in the MC treatment compared to the DW treatment at the same concentration of ozone.

• Journal of Ecology and Environment
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• 제41권11호
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• pp.318-327
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• 2017

Background: A typical sewage treatment plant is designed for organic and nutrient removal from municipal sewage water and not targeted to eliminate micropollutants such as pesticides, pharmaceuticals, and nano-sized metals which become a big concern for sustainable human and ecological system and are mainly discharged from sewage treatment plant. Therefore, despite contaminant removal by wastewater treatment processes, there are still remaining environmental risks by untreated pollutants in STP (sewage treatment plant) effluents. This study performed aquatic toxicity tests of raw wastewater and treated effluents in two sewage treatment plants to evaluate toxicity reduction by wastewater treatment process and analyze concentration of contaminants to reveal potential toxic factors in STP effluents. Methods: Water samples were collected from each treatment steps of two STPs, and acute and chronic toxicity tests were conducted following USEPA (United States Environmental Protection Agency) and OECD (Organization for Economic Cooperation and Development) guidelines. Endpoints were immobility for mortality and reproduction effect for estrogenicity. Results: Acute $EC_{50}s$ (median effective concentration) of influents for Seungki (SK) and Jungnang (JN) STPs are $54.13{\pm}32.64%$ and $30.38{\pm}24.96%$, respectively, and reduced to $96.49{\pm}7.84%$ and 100%. Acute toxicity reduction was clearly correlated with SS (suspended solids) concentration because of filter feeding characteristics of test organisms. Chronic toxicity tests revealed that lethal effect was reduced and low concentration of influents showed higher number of neonates. However, toxicity reduction was not related to nutrient removal. Fecundity effect positively increased in treated wastewater compared to that in raw wastewater, and no significant differences were observed compared to the control group in JN final effluent implying potential effects of estrogenic compounds in the STP effluents. Conclusions: Conventional wastewater treatment process reduced some organics and nutritional compounds from wastewater, and it results in toxicity reduction in lethal effect and positive reproductive effect but not showing correlation. Unknown estrogenic compounds could be a reason causing the increase of brood size. This study suggests that pharmaceutical residues and nanoparticles in STP effluents are one of the major micropollutants and underline as one of estrogenic effect factors.

• 한국환경과학회지
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• 제22권12호
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• pp.1643-1650
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• 2013

This study investigated water quality of effluents and stream from the sewage treatment plants located at Gumi Complex 4, Gumi, and Wonpyeong in Gumi. Downstream region was found to increase the concentration of nutrients for sewage treatment plant effluent. Both phosphorus and nitrogen were accounted most as soluble form. In particular, the high ratio of dissolved effluent of sewage treatment plants were investigated. In the streams, Phosphorus concentration was high during rainy season and nitrogen concentration was high in the dry season. Sewage treatment plant effluent was relatively less microbial activity and nutrient concentrations were higher in the winter. TN/TP ratio was the highest in the upstream region and the lowest in the sewage treatment plant effluent. The effect of the nutrient matter from a discharge of a sewage treatment plant on rivers varied depending on the size of the river and the treatment plant. However, the influence of the concentration was greater than that of flowrate. Sewage treatment plant effluent loads phosphorus, nitrogen accounted for 8% and 6% respectively at the point N3 of the Nakdong river.

• 한국수소및신에너지학회논문집
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• 제22권6호
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• pp.765-771
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• 2011

This study was conducted to investigate the effect of heat treatment on the start-up performance for anaerobic hydrogen fermentation of food waste. The result showed that hydrogen production was $0.61{\pm}0.31$ mol $H_2$/mol hexose with heat-treatment of food waste at $70^{\circ}C$ for 60 min whereas it was $0.36{\pm}0.31$ mol $H_2$/mol hexose without heat-treatment of one. The heat treatment of food waste enhanced hydrogen yield due probably to the increase of hydrolysis as well as the decrease of non-hydrogen fermentation microorganisms. The removal efficiency of carbohydrate in reactors regardless of heat treatment of food waste maintained over 90%. The hydrogen conversion efficiency from food waste was 1.7-6.3% with heat-treatment whereas it was 0.7-4.5% without heat-treatment. At the time of switchover from batch to continuous operation, lactate concentration was high compared to the n-butyrate concentration in anaerobic hydrogen fermentation reactor without heat-treatment. Anaerobic hydrogen fermentation of food waste with heat treatment was stable in start-up periods because lactate concentration could be maintained at a relatively low compared to n-butyrate concentration due to the decrease of non-hydrogen fermentation microorganisms.

• 약학회지
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• 제35권2호
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• pp.99-110
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• 1991

This study was initiated to investigate the effects of organic germanium on cadmium and mercury intoxication. The effect was determined by the metallothionein induction in liver and kidney. Male rats (Sprague-Dawley) were treated with CdCI$_{2}$ (2mg/kg), HgCI$_{2}$ (1 mg/kg) and organic germanium (GE-132) (100 mg/kg) in single and in combination via intraperitoneal injection or intragastric administration every other days for 17 days. Experimental animals were sacrificed after 7, 12 and 17 days treatment. The serum transaminase activities (SGOT, SGPT), concentration of metal and metallothionein, metal-binding capacity of metallothionein in liver and kidney were determined and pathomorphological observations were undertaken. The combined treatment of GE-132 and CdCI$_{2}$ significantly decreased the increment of serum transaminase activities in rats treated with CdCI$_{2}$ only, but the combined treatment of GE-132 and HgCI$_{2}$ did not affect to activities of transaminases induced by mercury only. The concentration of metals (Cd and Hg) except Ge in the liver and kidney of rats increased with the time of treatment. Mercury concentration in kidney of rat treated with HgCI$_{2}$ only was significantly higher than the combined treatment of GE-132 and HgCI$_{2}$. The combined treatment of GE-132 and CdCI$_{2}$ significantly increased the concentration of metallothionein in liver compared to the CdCI$_{2}$ only, although the concentration of cadmium in liver were not significantly different between two groups. This indicates that GE-132 decreased toxicity of cadmium in liver by promoting metallothionein induction. There were no significant differences in metallothionein concentration in liver and kidney of rats between the combined treatment of GE-132 and HgCI$_{2}$ and HgCI$_{2}$ only. Metal-binding capacity of metallothionein varied with each time intervals in liver and kidney of metals treated rats except the liver of the combined treatment of GE-132 and CdCI$_{2}$. This finding explains the concentration of metallothionein in liver keeps abreast with the concention of metal. Furthermore, the combined treatment of GE-132and CdCl$_{2}$ revealed pathologically less changes in liver tissue than CdCl$_{2}$ only; the damages of liver cell, such as lobular necrosis and portal inflammation, were relieved and appeared more later. From the above results, organic germanium is considered to have some beneficial effect on the protection of liver from the cadmium intoxication.

• 한국식품저장유통학회지
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• 제30권4호
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• pp.654-662
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• 2023

본 연구는 다양한 생리적 기능성을 함유한 섬쑥부쟁이의 활용도를 높이기 위해 효소처리농도 및 처리시간에 따른 품질 변화를 조사하였다. 효소처리농도 및 시간에 따른 섬쑥부쟁이 추출물의 pH 변화는 pH 5.56-5.76으로 무처리구(pH 5.88)보다 낮아지는 경향을 나타내었으며, 가용성 고형분 함량은 처리농도 의존적으로 증가하는 경향을 보였으며, 색도 변화는 처리시간이 증가할수록 적황색으로 변화됨을 확인할 수 있었다. 추출물의 유리당 함량 중 fructose 및 sucrose 함량은 효소처리를 하지 않은 무처리구(Control)에서 7.73% 및 6.78%로 가장 높은 함량은 나타내었으며, glucose 및 maltose 함량은 3.2%의 효소처리농도 및 60분의 처리시간(C구)에서 6.91% 및 4.44%로 높은 경향을 나타내었다. 항산화 활성을 나타내는 총폴리페놀 함량은 1.6%의 효소처리농도 및 120분의 효소처리시간(E구) 7.38 mg GAE/g으로 가장 높은 함량을 보였으며, DPPH 및 ABTS 라디칼 소거활성은 3.2%의 효소처리농도 및 60분의 처리시간(C구)에서 가장 높은 활성을 나타내었다. 이상의 결과로 섬쑥부쟁이 건조 분말 소재화를 위한 효소처리농도 및 시간의 적정조건을 설정할 수 있었다.

• 한국염색가공학회지
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• 제20권2호
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• pp.9-18
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• 2008

Wool has excellent properties, such as heat retention, absorbency, and elasticity, but it has a disadvantage in washability because the fabric will felt and shrink greatly. Felting causes the interlocking of the fiber surface scales with one another. Therefore, the studies on wool finishing have been focused on shrink proofing. Precedent researches on wool shrink proofing are mostly on eco-friendly method. using enzyme. The purpose of this study is to examine the effect of L-cysteine, EDTA in papain treatment of wool fabrics. The specific contents of study are as follows. Depending on pH, temperature, treatment time, enzyme concentration and L-cysteine, EDTA concentration, weight loss, tensile strength, whiteness, SEM were examined. Each papain treatment conditions depending on L-cysteine, EDTA were optimized from these properties. Papain had very low activation without activators. The optimum conditions of papain treatment were pH 7.5, temperature $75^{\circ}C$, time 30minutes(L-cysteine), 180minutes(EDTA) and papain concentration 5%(o.w.f.). In the use of papain 5%(o.w.f.), the activators optimum concentration was L-cysteine 2%(o.w.f.), EDTA 7%(o.w.f.)

• 한국표면공학회지
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• 제36권3호
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• pp.277-283
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• 2003

Electrochemical techniques were used to study the surface treatment for improving the pitting corrosion resistance of 304L stainless steel by inhibitors in chloride medium. Sodium molybdate (in concentration range : 0.005-80 g/l) , sodium nitrite (in concentration range : 0.001-50 g/l) and their mixture were used for this study. It was found that, molybdate and nitrite were good passivators for 304L stainless steel, but molybdate was not able to prohibit the pitting ; nitrite prevented pitting corrosion of 304L stainless steel only at the concentration more than 25 g/l. The relationship between pitting potentials and concentrations of inhibitors in the logarithm expression obeyed the linear function. It was found that the surface treatment by mixture of two inhibitors enables stainless steel to have increased the corrosion resistance , the pitting corrosion of 304L stainless steel was completely prohibited by the mixtures of molybdate and nitrite in ratio min, with $m\;\geq\;3\;and\;n\;\geq\;10$. The interesting cases on electrochemical measurement of threshold of inhibitors concentration combination for optimum surface treatment were described.