• 상하수도학회지
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• 제26권6호
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• pp.825-831
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• 2012

The retrofitting of a thickening unit process is widely considered in municipal wastewater treatment plants in Korea to enhance the anaerobic digestion efficiency. The authors examined the effect of feed concentration (2-34.1 g VS/L) and feed to microorganism (F/M) ratio (0.50-1.35 g VS/g VS) on anaerobic batch digestion of sewage sludge. Methane yield over 90 mL $CH_4/g$ $VS_{feed}$ was found at a feed concentration in the range of 12-26 g VS/L and a F/M ratio below 0.6 g VS/g VS. A high F/M ratio decreased methane yield and rate with oragnic acid accumulation. As sudden increase of sewage sludge concentration prior to anaerobic digestion would jeopardize the digester performance due to the rasied F/M ratio, gradual increase of the sludge feed concentration or an additional biomass retention in the digester is recommended.

• 한국세라믹학회지
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• 제41권4호
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• pp.323-327
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• 2004

본 연구는 석회석, 셰일, 전로슬래그, 플라이 애쉬를 사용한 혼합원료에 대해 보통 포틀랜드 시멘트 원료로서 하수슬러지 소각재의 사용에 대해 조사하였다. 이와 관련하여 원료 중 셰일에 대한 하수슬러지의 적정 치환 비율을 확인하였으며, 1,300, 1,350, 1,400, 1,450, 1,50$0^{\circ}C$에서 1시간 혼합원료를 소성하였다. 이후 공기중 급냉을 시행하였으며, XRD, SEM을 통하여 합성된 클링커의 특성을 평가하였다. 또한, 클링커의 미반응 산화칼슘을 측정하여 소성성에 대한 결과를 얻었다.

• 상하수도학회지
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• 제29권1호
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• pp.57-63
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• 2015

Recently, Korea's municipal wastewater treatment plants generated amount of wastewater sludge per day. However, ocean dumping of sewage sludge has been prohibited since 2012 by the London dumping convention and protocol and thus removal or treatment of wastewater sludge from field sites is an important issue on the ground site. The hydrothermal carbonization is one of attractive thermo-chemical method to upgrade sewage sludge to produce solid fuel with benefit method from the use of no chemical catalytic. Hydrothermal carbonization improved that the upgrading fuel properties and increased materials and energy recovery, which is conducted at temperatures ranging from 200 to $350^{\circ}C$ with a reaction time of 30 min. Hydrothermal carbonization increased the heating value though the increase of the carbon and fixed carbon content of solid fuel due to dehydration and decarboxylation reaction. Therefore, after the hydrothermal carbonization, the H/C and O/C ratios decreased because of the chemical conversion. Energy retention efficiency suggest that the optimum temperature of hydrothermal carbonization to produce more energy-rich solid fuel is approximately $200^{\circ}C$.

• 한국물환경학회지
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• 제18권2호
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• pp.189-199
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• 2002

Nitrogen, in its various forms, can deplete dissolved oxygen levels in receiving waters, stimulate aquatic growth, exhibit toxicity toward aquatic life and affect the suitability of sewage for reuse. Pilot-scale Rotating Biological Contactor(RBC) experiments were conducted to examine biological nitrification, respectively, of municipal sewage with five different internal recirculation ratios of 0, 1, 2, 3, and 4 using the constant hydraulic loading of $205L/m^2{\cdot}day$. The use of internal recirculation improved nitrification on account of the dilution of biodegradable organic carbon in influent sewage down to 15 mg/L of $SBOD_5$ or less. Ammonium nitrogen of $14.3{\pm}2.4%$ was consumed by cellular assimilation without the occurrence of denitrification. The thickness of biofilm didn't seem effect significantly the nitrification and denitrification. Nitrification with internal recirculation was found to occur using hydraulic loading rate of as high as $205L/m^2{\cdot}day$, which was beyond the generally known values of it.

• 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.

• 한국환경보건학회지
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• 제32권1호
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• pp.27-35
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• 2006

This study was carried out to investigate the removal of nitrogen and phosphorus in municipal sewage depending on existence of biological coated media in BCM reactor. The reactor with biological coated media is the process combining $A_2/O$ process. The removal efficiencies for $COD_{Mn},\; BOD_5,\;SS$, T-N and T-P were $78\%,\;90.5\%,\;92.3\%,\;61.9\%,\;60.2\%$, respectively. The specific nitrification rate$(mgNO_3-N/gMLSS{\cdot}d)$ of Contact aeration basin was 52.2 and the specific denitrification rate$(mgNO_3N/gMLSS{\cdot}d)$ in anoxic basin was 95.1. Also, phosphorus release$(mgPO_4-P/gMLSS{\cdot}d)$ in Anaerobic basin was 71.8 and Phosphorus uptake$(mgPO_4-P/gMLSS{\cdot}d)$ in contact aeration was 27.1.

• 한국환경보건학회지
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• 제18권1호
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• pp.58-62
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• 1992

The objective of this study is to investigate the generation rates, composition, propertion and lower heating values of each material in the municipal solid wastes(MSW) as well as the effect of landfill leachate on the environment in Taejon. The results are as follows: 1. The annual average generation rate of MSW in Taejon is approximately 1.7kg/c.d. 2. The weight percent of combustible matters is on average 80 and the lower heating value of MSW is measured to be more than 1,700 kcal/kg after removing the briquette component. 3. It is necessary for us to take a proper management system for leachate treatment in the landfill because it has many problems in the sewage and groundwater. 4. It is recommeded that MSW be treated by multiple methods such as the sanitary landfill, resources and recovery, composting and incineration.

• 공업화학
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• 제33권5호
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• pp.532-537
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• 2022

The need for obtaining treated wastewater that meets high quality standards for discharge or reuse necessitates the use of highly efficient wastewater treatment techniques. In the present study, experiments have been carried out to reduce the concentration level of biological oxygen demand (BOD), chemical oxygen demand (COD), and total dissolved solids (TDS) from the wastewater sample. Treatment of sample of a real municipal wastewater collected from a sewage treatment plant (STP) was carried out in an electrochemical membrane bioreactor (EMBR). The EMBR was operated continuously for five days, and readings were taken at regular intervals. This paper has experimental results conducted in EMBR that indicate reduction of BOD, COD, and TDS levels of up to 32.25%, 29.25%, and 31.93%, respectively. Further, it was observed that a current of magnitude of 0.00752 mA was generated due to the metabolic activities of bacteria present in municipal wastewater, which gradually decreased day by day due to the decay of bacteria.

• 한국환경보건학회:학술대회논문집
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• 한국환경보건학회 2005년도 Proceedings of KSEH.Minamata Forum
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• pp.51-53
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• 2005

Disposal of waterwork sludge is important problem in WTP(water treatment plant). Purpose of this study is treated municipal waste water chemically using sludge that is produced in waterwork plant by link to reutilize waterwork sludge. Municipal waste water that use in an experiment used is produced at C university, and is SS 220 mg/L, BOD 145 mg/L, COD 160 mg/L, T-N 52 mg/L and T-P 2.6 mg/L. Used Alum, polymer coagulant and coagulant aid (diatomite, powered activated carbon) as CaO, coagulant as alkaline aid by chemical treatment medicine. In case of does slow speed agitation and stations after pours waterwork sludge in sewage and alkaline aid and coagulant at rapidly mixing the colloidal creation speed is fast and fine colloids concentration was high but settling time is shortened a little and removal rate of pollutant improved by $60{\sim}99%$.

• 한국해양환경ㆍ에너지학회지
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• 제6권4호
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• pp.37-44
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• 2003

목포항 해양수질개선에 대한 목포하수처리장 가동의 기여도를 평가하고 목포하수처리장 가동 후에 목포항에 유입하는 오염부하의 변화를 산정하기 위하여, 하수처리장 가동 전인 1997년 여론부터 1998년 봄까지의 건조기에 육지로부터 목포항에 유입하는 오염부하를 조사하고 목포항 주변의 하천들과 처리장 유출수의 계절별 유량 및 수질을 기초로 하여 유입오염부하를 산정하였다. 또한 하수처리장 가동 후인 1998년 겨울부터 1999년 볼까지 목포항에 유입하는 오염부하를 조사하고 목포하수처리장의 유입수 및 유출수의 오염부하를 산정하였다. 하수 처리장의 처리율은 화학적산소요구량(COD)이 약 49%, 총부유성고형물(TSS)이 약 76%, 휘박성부유물(VSS)이 약 79%, 총질소(T-N)가 약 3%, 용존무기인(DIP)이 약 7%, 총인(T-P)이 약 29%, 용존무기질소(DIN)가 약 -32%를 보였다. 하수처리장 가동으로 인한 목포항 내항수역 유입오염부하 변화율은 COD가 약 56%, TSS가 약 78%, VSS가 약 84%, DM이 약 45%, T-N이 약 22%, T-P가 약 34%, DIP가 약 -14%를 보였다. 목포항 전역으로 유입하는 총오염부하의 감소에 대한 하수처리장 가동의 기여율은 COD가 약 3%, TSS가 약 3%, VSS가 약 5%, DIP가 약 1%, T-P가 약 3%, DIN이 약 -1%로 나타났다.