• 한국물환경학회지
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• 제25권4호
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• pp.553-559
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• 2009

Currently, small scale sewage works are getting increase in Chung Nam Province and it is strongly required for those plants to get the information of optimized procedures and technologies. Most processes for sewage works in Korea were designed for large scale plants, so many difficulties are observed in small scale sewage works. This study was conducted to evaluate the propriety of O&M and construction cost for sewage treatment plants in Chung Nam Province. The treatment results and process stability of 32 public sewage treatment plants were also investigated. It is expected to provide optimum O&M and construction cost for future small scale sewage works and improving projects of existing plants by these results. Pollution problems caused by small scale plants are usually restricted to small areas; however, in view of the high cost per unit population, treatment requirements and alternatives have to be studied carefully. In comparison to larger plants, more pronounced and different boundary conditions such as unstable influent load, per capita costs and a large variety of feasible treatment and disposal systems were considered.

• 환경위생공학
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• 제7권2호
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• pp.37-52
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• 1992

Since the first sewage treatment plant was constructed in 1976, the sewerage systems of Korea have been rapidly expanded. As of the end of 1991, 22 sewage treatment plants with total capacity of 5.4 million tons/day are in operation which is equivalent of 3395 total daily sewage generation. Total extension of sewer 39.534 km in 1990 which is 55% of the target extension for the year 2001. However, the most sewage treatment plants employ activated sludge process which may not be suitable for medium and/or small scale plants. The poor existing sewer systems do not effectively collect and transport sewage to adversely affect the function of sewage treatment plant. To select the appropriate treatment system, the cities are classified into 3 categories such as large and medium size inland cities, small size cities and coastal cities. Considering the criteria suggested during this study, appropriate treatment processes were selected for each category. Conventional activated sludge process and step aeration process were found to be the most appropriate for big inland cities while biological nutrient removal processes should be considered for the cities discharge the effluent to lakes or reservoirs. RBC or Oxidation Ditch process might be appropriate for the medium size cities while several processes which do not require skilled operation and maintenance were suggested for the small cities. Ocean discharge after primary treatment can be considered for some east coast cities, Appropriate methodology to rehabilitate the existing sewers and strategy to convert combined sewer system to separate sewer system were proposed. This paper also include the appropriate management system for industrial wastewater, sludge and nightsoil.

• 한국습지학회지
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• 제23권2호
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• pp.183-188
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• 2021

소규모 하수처리장의 경우 유입수량의 변동폭이 크고 하수관거 노후화로 인한 불명수 유입 등에 의해 하수처리 운영이 어려운 것으로 보고되고 있다. 특히, 동절기 수온저하로 인한 전반적인 운영문제가 많아 본 연구에서는 산악지역에 위치한 소규모 하수처리시설의 운영현황과 온도에 따른 수질변화를 분석하였다. BOD, COD, SS의 경우 온도에 따라 방류수 수질 농도가 크게 변화하는 것으로 나타났으며, 특히 COD가 많은 영향을 받는 것으로 나타났다. 이에 한시적으로 동절기 수온 저하 대책을 적용하고자 생물반응조 수위를 0.4m 상승시켰으며, 생물반응조 덮개를 설치하고 운영하였을 때 결과를 비교 분석한 결과 유의미한 개선효과가 발생하였다. 이외 동절기 생물반응조 처리효율 저하에 대한 개선방안을 생물반응조 체류시간 연장하는 방안으로 생물반응조 규격을 확대하는 방안, 유량조정조를 신설하고 외부반송하는 방안, 무산소에 산기장치를 설치하여 동절기 비상시 호기조로 사용하는 개선방안을 제시하였다. 본 연구결과는 동절기 소규모 하수처리시설 운영방안에 대한 기초자료로 활용될 수 있을 것으로 판단된다.

• 한국물환경학회지
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• 제38권5호
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• pp.231-239
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• 2022

In this study, we applied ENERWATER to evaluate the energy consumption labeling of wastewater treatment plants in Korea using the Korea sewerage statistics data. The results showed that the energy label status was excellent in the SBR process for small and medium-scale wastewater treatment plants and the A2O process for large-scale wastewater treatment plants. The energy labeling of wastewater treatment plants of 50,000 tons capacity was excellent. The statuses of metropolitan cities and Jeollanam-do province were excellent. We analyzed the effects of renewable energy on wastewater treatment plants' energy consumption and found out that digestion gas for large-scale plants and photovoltaic energy for small-scale plants were effective in improving energy labeling. In addition, we compared the energy labels of four wastewater treatment plants in "Z" city and wastewater treatment plant "X" had the best energy label, and the wastewater treatment plants "V" and "Y" had to be selected as priorities for the energy diagnosis and improvement project. In a comprehensive conclusion, the applicability of ENERWATER was confirmed based on sewage statistics data and labeling can be used to set priorities for the energy diagnosis and improvement project.

• 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.

• 동력기계공학회지
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• 제10권4호
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• pp.105-110
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• 2006

Among many other alternative energy resources, small scale hydro power has been brought into attention as a reliable source of energy today, which had been relatively neglected since 1960s. Especially, Kaplan micro-turbine can be applied to various kind of small hydro power plants, such as reservoirs for agriculture purpose, sewage treatment plants and water purification plants. However present low head of Kaplan micro-turbines and small scale hydro turbines, have limitations in the minimum required head and flow rate for efficient operation. This research is to develop modeling analysis for the Kaplan micro-turbine, which can improve economical features of small hydro power plants. The contents and scope of this research are the efficiency improvement of Kaplan micro-turbine.

• 한국물환경학회지
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• 제25권5호
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• pp.778-784
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• 2009

The purpose of this study is to figure out the differences of the inflow rates of Sewage Treatment Plants (STP), invested by public fund or public-private partnership (PPP). This paper finds that the average ratio of sewage inflow according to facility capacities (medium and small scale STP) was either nearly below 30% or above 100% in the first year. As the size of STP increased, there was decrease in the accuracy of demand assumption. This was because the operation time when the ratio of sewage inflow was uniform was different according to the size of STP, whereby the time was short when the STP were small. The design average ratio of sewage inflow was 10% larger than the real average ratio; this was considered overdesigned. In the case of a plant built by the PPP scheme, the average ratio of inflow of the STP before an abolition of MRG was larger than after the abolition of MRG. This may be explained by moral hazard from too much reliance on MRG. After the abolition of MRG, the demand risk of PPP was shifted from a PPP project to a conventional project.

• 한국습지학회지
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• 제22권2호
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• pp.130-138
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• 2020

2017년 기준 서울시 및 광역시의 하수도 보급률은 90% 이상의 높은 하수도 보급률을 보이며, 국내하수처리장의 개소 수는 2010년 3,064개에서 2017년 기준 4,072개로 약 25% 증가 증가하였다. 그중에서도 SBR계열 공법으로 운영 중인 하수처리장은 현재 585개로 2010년 대비 17% 증가한 것으로 나타났다. 상수원의 수질 개선과 소규모하수도 시설의 운영개선을 위해 안동 임하댐 권역 내 하수처리장 500㎥/일 이상 3개소 및 500㎥/일 미만 46개소, 총 49개소 시설을 대상으로 모델링을 적용하여 공정개선방안을 연구하였다. 모델링을 위한 개선안으로 5년간 운영자료 등을 검토하여 후보군을 도출하였다. 49개소의 시설은 총 12가지 종류의 공법으로 운영되고 있으며, 이 중에서 SBR공법의 500㎥/일 이상 시설 1개소와 500㎥/일 미만의 46개소를 3개 유형으로 그룹 분류를 하여 운영 개선이 가능한 9개소를 선정하였다. 500㎥/일 이상 1개소에 모델링를 적용한 결과, SRT 조절을 통해 방류수 수질 개선이 가능했으며, 소규모 처리장 9개소에 적용한 결과 총 인의 제거율을 최대 14.4% 개선할 수 있는 것으로 나타났다. 이에 본 연구의 결과자료는 공공 하수처리시설 및 마을 하수도 시설에 대한 개선 및 운영 개선 방안으로 활용될 수 있을 것으로 판단된다.

• 한국물환경학회지
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• 제26권2호
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• pp.200-207
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• 2010

The sewage treatment plants to be built to improve the water quality of the Mankyung River will total 11, of which combined capacity will reach $39,850m^3/day$, and saying in detail, 5 at Gunsan city, 2 at Iksan city, 1 at Kimje city and 3 at Wanju gun, The scenario for water quality improvement was developed, considering the conditions of plant operation ratio and the accomplishment of the water quality target (BOD 4.4 mg/L, T-P 0.356 mg/L) at the end of the watershed of Mankyung B was predicted, making use of QUAL2E model. As a result of prediction using QUAL2E model based on scenarios with 70% and 100% of operation ratio, respectively, at 11 plants in 2010, the water quality at the watershed of Mankyung B was estimated at 4.322 mg/L which was lower than the target of BOD 4.4 mg/L, indicating the target water quality was achieved, when it comes to 70% of operation ratio, But in case of T-P, it was estimated at 0.565 mg/L, which was higher than the target. When it comes to 100% of operation ratio, T-P also was 0.563 mg/L which exceeded the target, 0.356 mg/L. As indicated above, the effect of water quality improvement appeared very insignificant, which was attributable to the limit of small scale sewage treatment plant in total reduction capacity. Hence, the measures for additional reduction in a bid to achieve the target water quality of T-P at the designated location need to be taken, and the measures to build the Sewage treatment facilities at the place where the pollution is significantly caused by T-P appeared to be required as well.

• 한국물환경학회지
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• 제33권1호
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• pp.63-69
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• 2017

Small size privately owned wastewater treatment plants have been difficult to treat their wasted sludge and maintain steady effluent quality compared with publicly owned wastewater treatment plants. Therefore, this study has focused on treatment efficiency enhancement, specially nitrogen removal efficiency by recycling dewatering filtrate as an alkalinity additive from filter press using $CaCO_3$. As the result, it was found that the optimal mixing ratio between the excess sludge and $CaCO_3$ was 1:2. The major operation parameters such as specific substrate utilization rate, specific nitrification rate, and specific denitrification rate were also improved 64% ($0.048-0.079mg\;BOD_5/mg\;MLVSS{\cdot}day$), 35% ($0.020-0.027mg\;NH_3-N/mg\;MLVSS{\cdot}day$) and 68% ($0.051-0.086mg\;NO_3{^-}-N/mg\;MLVSS{\cdot}day$), respectively, after the adoption of new methods. Therefore, both the problem of sludge treatment at small scale plants and the need for efficiency improvement could be solved.