• 상하수도학회지
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• 제11권1호
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• pp.64-73
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• 1997

Most of the municipal wastewater treatment plants operated in Korea are designed for high concentrations municipal sewage. However, activated sludge process employed by municipal wastewater treatment plant is operated at low organic loading. The objective of this study was to determine optimum operating condition of activated sludge process for treatment of low concentration municipal sewage. Three bench scale activated sludge reactors were operated to investigate the effect of HRT and SRT on the COD and TSS removal efficiency. The average concentration of TSS, SCOD, SBOD and TKN in influent were 118mg/l, 61mg/l, 21mg/l, and 12mg/l, respectively. The activated sludge reactors operated with various HRT and SRT showed about 89-93% TSS removal efficiency. HRT and SRT does not affect the TSS removal efficiency of actvatied sludge process significantly. However, HRT affected the SCOD removal efficiency slightly. As the HRT decreases from 13hours to 3hours, the SCOD removal efficiency decreases from 67% to 56%. The average effluent TCOD concentration of the reactor operated with 3hours of HRT was approximatly 40-45mg/l. Kinetic coefficient yield (Yt) and decay coefficients(Kd) were 0.594-0.954 mgMLVSS/mgCOD and $0.0197-0.0317day^{-1}$, respectively. Low concentration municipal sewage can be treated with 3 hours of HRT without effluent quality deterioration and SRT does not affect the substrate removal efficiency at this operation condition.

• 한국물환경학회지
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• 제32권3호
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• pp.253-260
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• 2016

To reduce energy consumption in wastewater treatment plants (WWTPs), renewable energy applications such as small hydropower, solar energy, and wind energy are popular. However, it should be noticed that energy originated from operation of wastewater treatment process can be reduced through optimized operation based on analysis of factors affecting energy. In this research, the relationship to the various operational variables and influent factors was explored using correlation analysis and decision tree algorithm. Due to the non-linear characteristics of the process, it was difficult to find clear linear patterns through correlation analysis. However, decision tree algorithm showed its usefulness in uncovering hidden patterns that consume energy. As operational factors, influent flowrate, the amount of aeration, nitrate recycling pumping rate, and sludge wasting pumping rate were selected as important factors. For environmental factors associated with influent compositions and removal rate, BOD and T-N removal rate were selected as significant factors.

• 공업화학
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• 제24권1호
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• pp.38-43
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• 2013

ETA (ethanolamine)는 원자력 발전소 2차계통의 pH 조절제인 암모니아 대체 물질로 2001년부터 이용되고 있다. 환경적 측면에서 난분해성 유기물이며 현재 운영 중인 원자력 발전소 폐수처리설비로 처리가 불가능하다. 본 연구는 현장 시료를 사용하여 N와 COD 제거하기 위한 최적 공정과 사용 약품에 대하여 조사하였다. 폐수 중에 다량 함유되어 있는 ammonium ion은 diffused aeration system을 이용하여 95% 이상을 제거하고 혼합과산화물(sodium persulfate/sodium percarbonate)을 사용하여 산화시키고 응집제를 사용하여 물리 화학적으로 처리 후 90% 이상의 제거효과를 얻을 수 있었다.

• 한국농공학회지
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• 제45권2호
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• pp.126-137
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• 2003

The feasibility study of UV-disinfection system was performed for disinfection of effluent from wastewater treatment plant. Three low-pressure UV lamps of 17, 25, and 41 W were examined with various flow rates. Low-pressure UV lamps of 17W were examined with various turbidity, DOM (dissolved organic matter), and SS (suspended solid). The pilot plant was a flow-through type UV-disinfection system, and the range of exposure time varied from 5 to 40 seconds, turbidity from 0 to 40 NTU, DOM from 0 to 30 mg/L, and SS from 10 to 40 mg/L. The 41W lamp demonstrated complete disinfection showing no survival ratio in all the experimental conditions, and generally 17W and 25W lamps also showed high removal ratio over 97%. For the same UV dose (UV intensity times exposure time), high intensity-short exposure conditions showed better disinfection efficiency than low intensity-long exposure conditions. While the effects of turbidity and DOM were not apparent, the effects of SS was significant on the disinfection efficiency which indicates that SS control before UV-disinfection appears to be necessary to increase removal efficiency. Considering characteristics of effluent from existing wastewater treatment plants, cost-effectiveness, stable performance, and minimum maintenance, the flow-through type UV-disinfection system with high intensity and low-pressure lamps was thought to be a competitive disinfection system for wastewater reclamation.

• Environmental Analysis Health and Toxicology
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• 제29권
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• pp.15.1-15.7
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• 2014

Objectives This paper tried to review a recent research trend for the environmental exposure of engineered nanomaterials (ENMs) and its removal efficiency in the nanowaste treatment plants. Methods The studies on the predicted environmental concentrations (PEC) of ENMs obtained by exposure modeling and treatment (or removal) efficiency in nanowaste treatment facilities, such as wastewater treatment plant (WTP) and waste incineration plant (WIP) were investigated. The studies on the landfill of nanowastes also were investigated. Results The Swiss Federal Laboratories for Materials Science and Technology group has led the way in developing methods for estimating ENM production and emissions. The PEC values are available for surface water, wastewater treatment plant effluents, biosolids, sediments, soils, and air. Based on the PEC modeling, the major routes for the environmental exposure of the ENMs were found as WTP effluents/sludge. The ENMs entered in the WTP were 90-99% removed and accumulated in the activated sludge and sludge cake. Additionally, the waste ash released from the WIP contain ENMs. Ultimately, landfills are the likely final destination of the disposed sludge or discarded ENMs products. Conclusions Although the removal efficiency of the ENMs using nanowaste treatment facilities is acceptable, the ENMs were accumulated on the sludge and then finally moved to the landfill. Therefore, the monitoring for the ENMs in the environment where the WTP effluent is discharged or biomass disposed is required to increase our knowledge on the fate and transport of the ENMs and to prevent the unintentional exposure (release) in the environment.

• Korean Chemical Engineering Research
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• 제52권4호
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• pp.413-424
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• 2014

에너지원으로 바이오가스에 대한 잠재적 가능성이 인식되면서 최근에 바이오가스의 생산기술을 제고하고 에너지 효율을 개선하기 위한 기술개발이 지속적으로 진행되고 있다. 본 논문의 목적은 혐기성 소화 과정에서 바이오가스 생산을 증가시키기 위한 효과적이고 효율적인 슬러지 전처리 방법에 대하여 분석하였다. 이를 위해 본 논문에서는 각각의 전처리 방법의 장점과 단점을 분석하여 바이오가스 생산에 미치는 영향요인을 비교 분석하였다.

• 상하수도학회지
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• 제19권4호
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• pp.497-505
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• 2005

Domestic Sewage Treatment Plants are mostly based on biological treatment, in which large amounts of excess sludge are generated and occupy about 40 ~ 60% of the total sewage treatment costs. Several methods for sludge treatment has been so far reported as upgrading biodegradation of sludge; heat treatment, chemical treatment, including thermo-alkali and ozone, mechanical treatment including ultrasonic pulverization. But, it has a limitation in case of reducing the amount of excess sludge which are already producted. In this study, application of excess sludge reduction process using thermophilic aerobic bacteria for activated sludge was examined. The research was carried out two different stage. one for a biological wastewater treatment and the other for a thermophilic aerobic solubilization of the waste sludge. A portion of excess sludge from the wastewater treatment step was into the thermophilic aerobic sludge solubilization reactor, in which the injected sludge was solubilized by thermophilic aerobic bacteria. The solubilized sludge was returned to the aeration tank in the wastewater treatment step for its further degradation. Sludge solubilization reactor was operated at $63{\pm}2^{\circ}C$ with hydraulic retention time(HRT) of 1.5 ~ 1.7 day. Control group was operated with activated sludge process(AS) and experiment group was operated with three conditions(RUN 1, RUN 2, RUN3). RUN 1 was operated with AS without sludge solubilization reactor. RUN 2 were operated with AS with sludge solubilization reactor to examine correlation between sludge circulation ratio and sludge reduction ratio by setting up sludge circulation ratio to 3. RUN 3 was operated with sludge circulation ratio of 3 and MLSS concentration of 1,700~2,000mg/L to examine optimum operation condition. The quantity of excess sludge production was reduced sharply and in operation of RUN 3, sludge The quantity of excess sludge production was reduced sharply and in operation of RUN 3, sludge solubilization ratio and sludge reduction ratio were 53. 7%, 95.2% respectively. After steady state operation, average concentration of TBOD, SBOD, $TCOD_{Cr}$, $SCOD_{Cr}$, TSS, VSS, T-N, T-P of effluent were 4.5, 1.7, 27 .8, 13.8, 8.1, 6.2, 15.1, 1.8mg/L in the control group and were 5.6, 2.0, 28.6, 19.1, 9.7, 7.2, 16.1, 2.0mg/L in the experimental group respectively. They were appropriate to effluent standard of Sewage Treatment Plants.

• 한국농공학회:학술대회논문집
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• 한국농공학회 2002년도 학술발표회 발표논문집
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• pp.89-92
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• 2002

Among 172 wastewater treatment plants, eighty eight plats are found to be qualified for potential wastewater resources applicable to agricultural irrigation. The total effluent capacities are 4,042 thousand tonnes per day, which may be used to irrigated paddy fields of $156\;km^2$. Preliminary surveys have been made to inquire farmers and water managers about their preference for wastewater reuse. All of them expressed their willingness to accept the wastewater reuse. The surveyed water managers suggested microbiological treatments be made and exclusive prove for safety of wastewater irrigation be prerequisite to the practices. Further surveys with experts and water managers throughout the nation are needed before any conclusions are made.

• 상하수도학회지
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• 제26권3호
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• pp.443-451
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• 2012

Wastewater treatment plants need to reduce phosphorus in order to meet increasingly stringent regulations on phosphorus. This study evaluated the feasibility of dolomite as a coagulation aid to enhance phosphorus removal from secondary treated wastewater by chemical coagulation. Standard jar tests were conducted to evaluate the effect of dolomite addition on a coagulation process for phosphorus removal and to determine the optimum doses of coagulants and dolomite. Coagulants used with dolomite yielded a significant improvement in phosphorus removal and reduced total phosphorus concentrations below 0.02 mg/L in wastewater effluent. Dolomite has played an important role in enhancing phosphate adsorption and increasing pH, as a coagulation aid. The maximum removal efficiency of phosphorus in this study was yielded at 25 mg/l of dolomite and 20 mg Al/L of PAC dose. However, considering economic aspects, the optimum doses of dolomite and PAC were 10 mg/L and 15mg Al/L, respectively. Consequently, dolomite, a coagulation aid, can be used in coagulation processes to enhance the removal of phosphorus.

• 상하수도학회지
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• 제19권6호
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• pp.781-790
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• 2005

Granular Activated Carbon(GAC) is widely used in drinking water treatment. Many of the problems occurring in the GAC process are associated with the operation goal and performance. The purpose of this study were to evaluate the design, operation, and performance of granular activated carbon process in D water treatment plant. The optimal operation conditions of GAC process such as backwashing condition, granular activated carbon replacement time were discussed. The design, operation and performance of GAC process is influenced by their raw water characteristics and placement within the treatment process sequence. A critical analysis of plants experience and the information from the literature identifies the effectiveness of GAC process and indicates where modifications in design and operation could lead to improved performance. It would be useful to evaluate and optimize the GAC process in other treatment plant.