• 한국물환경학회지
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• 제22권5호
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• pp.905-912
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• 2006

In this paper, simulation methods of the system dynamics model developed by Das et al. (1997) for activated-sludge wastewater treatment plants are illustrated in an attempt to determine the operating rules and the policies related to capacity expansion of an activated-sludge wastewater treatment plant. For existing conditions, the analyses were performed by varying activated-sludge return rate to observe changes in effluent water quality and treatment efficiency. The effluent water quality is also analyzed for various average daily inflow conditions and activated-sludge return rates. As a result, without expanding the aeration tank, maximum average daily inflow that can satisfy the effluent water quality standard of BOD $0.02kg/m^3$ was determined as $2,840m^3/hr$, subject to 100% of activated-sludge return rate while other factors remain constant. When the activated-sludge return rate is less than 100%, expansion of the aeration tank is necessary and minimum sizes of the aeration tank to satisfy the effluent water quality standard were determined for various activated-sludge return rates. In addition, the total operating and maintenance as well as unit treatment cost regression equations for activated-sludge wastewater treatment plants are suggested by using the cost data that are obtained from Water and Wastewater Division, Ministry of Environment. The regression analyses showed that the economies of scale phenomena exist in the operating and maintenance costs of activated-sludge wastewater treatment plants.

• 한국물환경학회지
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• 제30권5호
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• pp.524-531
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• 2014

Korea has been trying to manage water quality of rivers and lakes in many ways. Ministry of Environment is making continuous efforts of operation control improvement such as strengthening effluent standards in sewage treatment plants and expanding Tele-Monitoring System (TMS). However, evaluation method for operations of sewage treatment plants and establishment system of effluent standards are inadequate. The objective of this study is to evaluate for operations of sewage treatment plants using statistics technique such as frequency analysis, percentile, normal distribution analysis. We used the effluent data (BOD, COD, SS) collected at 299 plants in 2012. The values were very low by comparison with standards. The Data followed a normal distribution. We think that distribution characteristics are closely related with effluent standards, especially T-P and BOD. Statistics technique attempted in this study can be used to evaluate for operations of sewage treatment plants and assess the appropriateness of effluent standards based on TBEL(Technology-based effluent limitation). And, this technique can be used to figure out the overall level of plants, the status of each plant and the favorable treatment process for each item (BOD, COD etc.). Data acquired through this method can be used to improve facilities and operation techniques and decide on a sewerage policy.

• 한국해안·해양공학회논문집
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• 제32권4호
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• pp.211-222
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• 2020

입자추적 실험 결과를 이용하여 새만금 배수갑문 유출수의 영향 범위 파악을 위한 방법론을 수립하고, 2017년을 대상으로 새만금 배수갑문 유출수의 영향 범위를 계절별 확률 분포로 제시하였다. 물질 수송 시간의 지표 중 하나인 water age를 계산하고 입자추적 실험 결과와 비교하여 계산 결과의 타당성을 입증하였다. 배수갑문 유출수는 신시 또는 가력 배수갑문을 중심으로 그 영향 범위가 방사형으로 증가하는데 계절풍의 영향으로 동계에는 남측으로, 하계에는 북측으로 영향 범위가 치우치는 것으로 예측되었다. 예측 결과는 2017년 상황에 한정되지만, 본 연구에서 수립한 입자추적 실험을 이용한 배수갑문 유출수 영향 범위 산정 기법은 현재 변화하고 있는 새만금 해역의 장래 배수갑문 유출수의 영향 범위 산정 연구에 활용이 가능하다.

• 한국환경과학회지
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• 제1권2호
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• pp.81.2-92
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• 1992

Growing algae spread over open water surface of water hyacinth system the leaves of hyacinth prevented the passage of sunlight through the water surface. The objectives of this study were to investigate the effects of the algae growth on the effluent of water hyacinth wastewater treatment systems operated with the variation of an organic loading rate between 190 to 550 kg COD/ha.day. The effluent from the system contained algae was discharged for about 2-3 weeks from the beginning of experimental operation of water hyacinth systems. BOD and 55 concentration of effluents during algae growthing periods were higher than those during the period of algae control. But nitrogen and phosphrous romoval efficiencies during in algae growthing periods were slighty higher than those during the period of algae control.

• 한국물환경학회지
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• 제24권6호
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• pp.676-681
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• 2008

The evaluation of the effluent water quality of sewage treatment plant is one of the most important factor in calculating total maximum daily loads (TMDLs). Current method to calculate 95% upper limit of effluent water quality of sewage treatment plant assuming normal distribution of data needs to be implemented in case of non-normal distribution. We have investigated the applicability of percentile ranking method as a non-parametric statistical analysis in case of non-normal distribution of data.

• 상하수도학회지
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• 제24권1호
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• pp.41-50
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• 2010

The influent and effluent baffle configurations seriously affect the hydraulic characteristics of the secondary clarifier in wastewater treatment plant. In this study, those baffle configurations were optimized by computational fluid dynamics(CFD) analysis and particle image velocity(PIV) test in order to obtain uniform flow in inlet region and to minimize upflow velocity in outlet region of the secondary clarifier. Theoretical analysis using CFD showed that more uniform flow could be accomplished when the influent baffle was located closely to the inlet opening. Effects of effluent baffle configuration on the upflow velocity in the outlet region of the secondary clarifier were analyzed with four types of effluent baffles which are widely adopted for secondary clarifier design. From the CFD analysis, McKinney baffle(EB-2) was estimated to be the most effective for restraining the upflow velocity in the outlet region and these trends were identified by PIV tests. In addition, the McKinney baffle showed the most uniform overflow velocity distribution around the weir.

• 상하수도학회지
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• 제9권2호
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• pp.77-83
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• 1995

The effluent from conventional nightsoil treatment plants contains nutrients, color and chlorides, in addition to residual organics and suspended solids, and thereby causes substantial pollution problems in receving water resources. In order to verify the usefullness of electrolysis in removing those residual pollutants from such conventional nightsoil treatment plant effluent, a bench scale experiment was conducted using sufficiently dilluted human nightsoil as experiment feeds. The result showed mean removals of 45% of total phosphorus and 85% of color, in addition 87% of residual BOD, 47% of residual COD and 85% of residual SS. The optimum electric current was found to be 15 ampere and the optimum hydraulic residence time 21/2 hour.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2010년도 춘계학술대회 초록집
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• pp.238.2-238.2
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• 2010

Recently, environmental pollution and energy depletion problems have been issued over the world. For this reason, many renewable systems have been developing. Of these, the Ocean Thermal Energy Conservation(OTEC) is drawing attention as the upcoming alternative energy source. In this paper, the efficiency of each of OTEC which harness the effluent from nuclear power plant was analyzed by using computer calculation. The result, shows that Ul-jin Nuclear Power Plant is the best place geographically and the regenerative cycle is most outstanding performance cycle for OTEC. The difference of temperature between surface water and deep water temperature should be greater than $20^{\circ}C$ in order to increase the efficiency.

• 한국방재학회:학술대회논문집
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• 한국방재학회 2007년도 정기총회 및 학술발표대회
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• pp.387-390
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• 2007

The mixing characteristics of heated water discharged from different types of effluents are simulated using a commercial software, Flow-3D model. In order to verify the model, the comparison of numerical results with the experimental data are conducted for each type of effluent, the submerged and surface overfall. It is observed that the numerical results show a reasonable agreement with the experimental data. Based on this study the application to the heated water discharge problem in the field can be expected as a further study and it can be the fundamental data when determining the type of effluent in a powerplant.

• 한국환경과학회지
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• 제22권10호
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• pp.1353-1361
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• 2013

The objectives of this paper are the characterization of the pretreatment of wastewater by microfiltration (MF) membranes for river maintenance and water recycling. This is done by investigation of the proper coagulation conditions, such as the types and doses of coagulants, mixing conditions (velocity gradients and mixing periods), pH, etc., using jar tests. The effluent water from a pore control fiber (PCF) filter located after the secondary clarifier at Kang-byeon Sewage Treatment Plant (K-STP) was used in these experiments. Two established coagulants, aluminum sulfate (Alum) and poly aluminum chloride (PAC), which are commonly used in sewage treatment plants to treat drinking water, were used in this research. The results indicate that the optimal coagulation velocity gradients (G) and agitation period (T) for both Alum and PAC were 200-250 $s^{-1}$ and 5 min respectively, but the coagulation efficiencies for both Alum and PAC were lower at low values of G and T. For a 60 min filtration period on the MF, the flux efficiencies ($J/J_0$ (%)) at the K-STP effluent that were coagulated by PAC and Alum were 92.9 % and 79.9 %, respectively, under the same coagulation conditions. It is concluded that an enhanced membrane process is possible by effective filtration of effluent at the K-STP using the coagulation-membrane separation process.