하수처리장의 에너지 효율성 개선 방안 연구

조을생 한국환경연구원 2011 기본연구보고서 Vol.2011 No.-

In the 60th anniversary of founding the Republic of Korea in 2008, ``Low Carbon, Green Growth`` was declared as the new national vision to cope with high oil prices and climate change. The national strategy for Green Growth was established with three main strategies and ten policy directions, and the Framework Act on Low carbon, Green Growth was enacted in April 2010. Municipal wastewater treatment facilities are considered energy-intensive environmental infrastructures, and they are regulated under the GHG Target management which sets and implements targets for emission reduction, energy conservation, and energy efficiency to respond against energy depletion and climate change. As a result, the importance of energy conservation and recovery in wastewater treatment plants (WWTPs) are being emphasized. In this study, the energy consumption characteristics of WWTP and energy management-related systems were investigated. Also, energy efficiency comparisons among WWTPs were carried out. Finally, measures to improve energy efficiency and energy management at WWTPs are presented. In the last decade, the electricity cost at WWTPs with the capacity of 500 m3/day or more increased by 10.6% per year, and compared to year 2002, the cost increased to 101.9% in year 2009. These increases can be attributed to increases in wastewater that must be treated and advanced treatment technologies equipped to comply with increasingly stringent discharge requirements, among other reasons. In response, the Ministry of Environment has developed the basic plan for energy independence at wastewater utility in 2010, which placed a goal to achieve energy self-sufficiency rate of 50% by 2030. The energy efficiency opportunities suggested in the basic plan can be grouped into three broad categories as follows; Replacement of aging equipments with more efficient equipments, and operational improvements Energy recovery, such as biogas, through anaerobic sludge digestion or small hydro power using a discharge of treated wastewater Alternative energy production from photovoltaic power generation, wind power, and others However, most pilot projects implemented with the government`s financial support are focused on energy recovery or alternative energy production rather than energy savings through energy efficiency and maintenance of WWTPs. In 1992, the US EPA introduced ENERGY STAR as a voluntary labeling program designed to identify and promote energy efficient products to reduce greenhouse gas emissions. The EPA expanded the label to wastewater utilities in 2005, and its goal is to have more than 50% of the nation`s WWTPs earn the ENERGY STAR label by 2012. In addition, the EPA has highly recommended wastewater treatment operators to adopt PDCA (Plan-Do-Check-Act) approach to enhance their energy efficient management systems. In other words, the EPA has encouraged and assisted wastewater utilities in implementing energy saving practices through their operational improvements, as well as renewable energy productions. In the EU, automatic control systems have been widely applied to minimize the costs associated with energy and energy efficiency over time, and provide improved control and operation over the unit treatment processes. Moreover, EU has relied on renewable energy productions to improve the energy efficiency of wastewater utilities. In Japan, emphasis on energy efficiency to overcome environmental issues, such as global warming response, are enforced throughout all industries, and the country has consistently introduced new technologies to improve its energy efficiency and production of energy. In many wastewater facilities, Japan has developed and used various alternative energy production technologies, such as biogas production, sewage heat recovery, small hydropower, and windmill power, to improve the efficiency of its facilities. In this study, the energy usage and energy efficiency of wastewater utilities were evaluated to explore ways to save energy via operational measures. Using the standards from the end of 2009, it was found that the amount of energy used by WWTPs (treating 500m3/d or more wastewater) increased with increasing wastewater treatment capacity. The unit energy usage of each treatment process was analyzed in terms of inflow, organic removal, and nutrient removal. Wastewater treatment processes employing the media consumed relatively lower power compared to other advanced treatment processes. Among the secondary treatment processes, the lowest consumption of power was found in the activated sludge process. As such, energy usages in the wastewater utilities are affected by various parameters, such as inflow, process, and influent concentration of pollutants. Moreover, the correlation of each characteristic parameter to energy was assessed to find a set of parameters that explained most of the variations in energy use among utilities. Based on these results, a multi-parameter lineal regression model that captured the impacts of key characteristics on energy use was developed to assess the energy efficiency of wastewater utilities. The results show that increases in inflow, influent COD concentration, and ratio of advanced treatment generally increased the energy use. On the other hand, increases in load factor (influent average flow/design flow) reduced the energy use. In the regression analysis, the energy efficiency was highest in the A2O advanced process, followed by activated sludge, other advanced treatment processes, media advanced process, RBC, oxidation ditch, membrane advanced process, and contacted aeration process. These results show that the membrane process (among the advanced processes) and the contacted aeration process (among the secondary processes) require more efforts in saving energy. Overall however, energy efficiency varied within the same process and similar-sized treatment plants. Thus, each WWTP needs to establish its own measure systematically to optimize their energy efficiency operation. To promote operation-based energy saving and energy efficiency measures which are individually suited for each waste treatment plant, the followings should be established: i) energy use DB for all wastewater utilities, ii) energy use monitoring system for the wastewater unit process, iii) organizational energy management team, iv) energy management system (EMS), and v) collaborative network of energy saving through exchanges of technical information. Moreover, vi) improvements in energy efficiency rating and incentive programs for wastewater utility are required since the commitments of plant staff members are critical in enhancing energy effectiveness. To ensure practitioners` expertise in efficient sustainable energy operation of WWTP, vii) allow for a longer unit rotation for technicians instead of frequent unit rotations. Also, viii) the R&D support for the field of integrated control system is needed to develop key technologies and improve the localization rate. Lastly, ix) the financing plan of the municipality must ensure the economic value of WWTPs to secure investors` investments in facilities and equipments for sustainable energy savings.

하수처리장 연계처리를 위한 가축분뇨 최적 처리공정 선정에 관한 연구

김충곤,신현곤 유기성자원학회 2012 유기물자원화 Vol.20 No.3

As the result of reviewing the linked treatment of water quality for treating process at public livestock wastewater treatment facilities for fair selection of the proper linked process in case of linking sewage treatment plant for livestock wastewater, in case of wastewater processed by bio-reactor that is only biologically-treated, the load factor showed relatively high as 1.67%(base on design quality), 2.59%(base on operation quality) regarding COD and 3.69%(base on design quality), 7.67%(base on operation quality) regarding CODMn but it is judged that there is nearly no influence on the operation of sewage treatment plan. And, in case of oxidized flotation-treated water & biofiltlation-treated water that are the advanced wastewater treatment, the load factor is approximately 1% and there is concern about the installation of excessive facilities in case of installing the advanced wastewater treatment. So, in case of considering the economic efficiency & stable operation of sewage treatment plant S, it is judged to be desirable to link with wastewater processed by bio-reactor that is biologically-treated. 가축분뇨처리수의 하수처리장 연계 시 적정한 연계처리 공정 선정을 위해 가축분뇨공공처리시설의 처리공정별 연계처리수질을 검토한 결과 생물학적처리만 거친 생물반응조 처리수의 경우 연계부하율이 CODMn의 경우 1.67%(설계수질 기준), 2.59%(운영수질 기준), T-P의 경우 3.69%(설계수질 기준), 7.67%(운영수질 기준)로 다소 높게 나타났으나 하수처리장 운영에 미치는 영향은 거의 없을 것으로 판단된다. 또한, 고도처리공정인 산화부상분리 처리수 및 생물여과 처리수의 경우 연계부하율은 1% 내외로 고도처리설비 설치 시 과대 설비설치의 우려가 있다. 따라서 S하수처리장의 경제성 및 안정적인 운영을 고려할 경우 생물학적처리인 생물반응조를 거친 처리수를 연계하는 것이 바람직할 것으로 판단된다.

국내 하수처리시설 에너지 등급 평가를 위한 ENERWATER의 적용 가능성에 관한 연구

박민오,이호식 한국물환경학회 2022 한국물환경학회지 Vol.38 No.5

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 inimproving 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.

농촌 지역에서 유입 유량이 소규모 하수처리장 처리 효율에 미치는 영향

임지열,길경익 한국습지학회 2016 한국습지학회지 Vol.18 No.3

농촌 지역 하수도 보급은 하천, 호소 및 습지와 같은 수계 수질 보호를 위해서 반드시 필요하다. 또한 안정적인 소규모 하수처리장 운영을 위해서는 유입 유량과 농도의 변화가 큰 소규모 하수도 특성을 고려해야 한다. 본 연구에서는 봉 화군 18개의 소규모 하수처리장 운전 결과를 통해 유입유량비 (유입 유량 / 설계 유량) 특성, 소규모 하수처리장 처 리 효율에 미치는 영향과 적정 유입유량비 산정에 관한 연구를 수행하였다. 분석 결과 유입유량비는 여름철에 가장 높은 것으로 나타난 반면, 유입 하수 농도는 가을철과 겨울철에 높은 것으로 나타났다. 유입유량비가 증가할수록 처 리 효율이 증가하는 경향을 보였으며, 영양염류 처리 효율이 유기물과 부유물질 처리 효율에 비해 민감한 영향을 받 는 것으로 나타났다. 안정적인 소규모 하수처리장 처리 효율을 위해서는 유입유량비 0.8 이상을 유지해야 할 것으로 판단된다. Sewerage supply in rural community is the important for water quality protection of water system such as river, lake and wetland. And characteristic of small scale wastewater system that have wide range of inflow and concentration in sewage should be considered for stable operation of small scale wastewater treatment plant. In this research, characteristics of flow ratio (flow / designed flow), effect on treatment efficiency of small scale wastewater treatment plant and assessment of optimal flow ratio were conducted through analysis on operation result of 18 small scale wastewater treatment plant in Bong-hwa gun. As a result, flow ratio shows the higher value during summer. However pollutants concentration in sewage was shown the higher concentration during autumn and winter. Treatment of small scale wastewater treatment plant is increased when flow ratio increased, and nutrient treatment efficiency is more sensitive to change of flow ratio than organic compound and suspended solids. According to this research result, it need to be maintained flow ratio 0.8 over value for stable treatment efficiency of small scale wastewater treatment plant.

Perfluorochemicals in Korean Wastewater Treatment Plants: Implications on Sources and Monitoring

주권호,김용환,김근영,송진영,이미란,최정권,최용주 대한토목학회 2021 KSCE JOURNAL OF CIVIL ENGINEERING Vol.25 No.6

The occurrence of perfluorochemicals (PFCs) in two wastewater treatment plants (WWTPs) in Korea, Plant I and G2, is investigated from a year-round sampling campaign. Plant I influent is characterized by the dominance of perfluorohexanesulfonate showing 10.8-fold higher per capita mass discharge value in the service area than that of Plant G2 service area. Plant G2 influent shows the dominance of perfluorooctanote and perfluorohexanoate, whose per capita mass discharge values are 3.7- and 11.8-fold higher than those of Plant I, respectively. Contrary to the dramatic difference of concentration and per capita mass discharge pattern of PFCs, the per capita mass discharge values for typical wastewater quality indicators are nearly identical for two WWTPs. This result implies that industrial contribution is significant for the PFC loading at the two WWTPs despite the fact that Plant I and G2 influents are officially reported to include only 0.4% and 7.5% of industrial wastewater in flowrate, respectively. This disagreement between the implication from the PFC data and the official report suggests the need to improve our knowledge on the impact of industrial sources on PFCs in WWTP influents, including those sources that are not officially registered or are poorly managed. The PFC fate during the wastewater treatment is slightly different between the two WWTPs, which can be partially explained by the different biological treatment processes applied. Seasonal variations in PFC concentrations observed in this study suggest that any monitoring program should be performed at least on a seasonal basis.

하수열에너지 공급 대상지 선정 방법론 개발: 잠재적 수요처의 연면적을 중심으로

박기홍,전창현,오재일 대한상하수도학회 2024 상하수도학회지 Vol.38 No.5

To mitigate carbon emissions, the government aims to transition to renewable energy sources including hydrothermal energy, specifically through wastewater heat recovery. This process involves extracting heat from wastewater or treated water. However, assessments of demand sources for local cooling and heating have predominantly focused on the proximity of nearby facilities, without conducting comprehensive demand analyses or defining explicit supply areas. This study proposes a methodology for prioritizing suitable wastewater treatment plants (WWTPs) for the implementation and expansion of renewable energy. The methodology is based on the gross floor area of potential wastewater heat demand surrounding WWTPs. Initially, potential supply and demand sources were identified based on the capacity of WWTPs and the gross floor area of buildings capable of utilizing wastewater heat. In the Republic of Korea, 330 WWTPs with a capacity of 5,000 m 3 /day or more have been recognized as demand sources for wastewater heat recovery. The provision of treated wastewater to structures located within a 500 m radius of the WWTPs for heat recovery is considered a feasible option. The potential wastewater heat demand and renewable energy cluster were identified among the surrounding buildings and complexes A total of 13 potential supplies were identified, provided that the gross floor exceeded 60,000 m². Finally, after prioritizing based on WWTPs with these conditions, the underground plant located in the downtown area was ranked as the highest priority. If further analysis of economic feasibility, CO 2 reduction, and energy efficiency are conducted, this approach can be expanded and applied within the framework the Water-Energy Nexus. Wastewater heat can be utilized not only as a renewable energy source but also as a means to enhance wastewater reuse through the supply of treated wastewater.

시설용량을 초과하는 폐수량의 유입확률 분석을 위한 극치분포모델의 적용에 관한 연구

최성현,유순유,박태욱,박규홍 대한상하수도학회 2016 상하수도학회지 Vol.30 No.4

It was confirmed that the extreme value distribution model applies to probability of exceeding more than once a day monthly the facility capacities using data of daily maximum inflow rate for 7 wastewater treatment plant. The result of applying the extreme value model, A, D, E wastewater treatment plant has a problem compared to B, C, F, G wastewater treatment plant. but all the wastewater treatment plant has a problem except C, F wastewater treatment plant based 80% of facility capacity. In conclusion, if you make a standard in statistical aspects probability exceeding more than once a day monthly can be ‘exceed day is less than a few times annually’ or ‘probability of exceeding more than once a day monthly is less than what percent’.

국내 하수처리시설에 인공지능기술 적용을 위한 사례 연구

김태우,이호식 한국물환경학회 2019 한국물환경학회지 Vol.35 No.4

In the recent years, various studies have presented stable and economic methods for increased regulations and compliance in sewage treatment plants. In some sewage treatment plants, the effluent concentration exceeded the regulations, or the effluent concentration was manipulated. This indicates that the process is currently inefficient to operate and control sewage treatment plants. The operation and control method of sewage treatment plant is mathematically dealing with a physical and chemical mechanism for the anticipated situation during operation. In addition, there are some limitations, such as situations that are different from the actual sewage treatment plant. Therefore, it is necessary to find a more stable and economical way to enhance the operational and control method. AI (Artificial Intelligence) technology is selected among various methods. There are very few cases of applying and utilizing AI technology in domestic sewage treatment plants. In addition, it failed to define specific definitions of applying AI technologies. The purpose of this study is to present the application of AI technology to domestic sewage treatment plants by comparing and analyzing various cases. This study presented the AI technology algorithm system, verification method, data collection, energy and operating costs as methods of applying AI technology.

공공하수처리장 침사지의 악취 배출계수 산정

장현섭,김성태,이종국,오남승,송지현 한국냄새환경학회 2017 실내환경 및 냄새 학회지 Vol.16 No.4

Odor emission factors (OEFs) are important parameters in characterizing odor sources, understanding emission patterns, designing abatement facilities, and providing appropriate control methods. In this study, OEFs for complex odor from grit removal chambers in publicly-owned wastewater treatment plants were determined, and the major operating conditions affecting the emission factors were investigated. In the main study site of “S” wastewater treatment plant, the averaged OEFs from the grit chamber were found to be 466.2, 162.6, and 54.7 OU/m2/min in summer, spring, and winter, respectively. OEFs from two other grit chambers in different wastewater plants were independently measured for comparison, and the values were in the same range as the OEF from S-site at a 95% confidence level. Nevertheless, the OEFs could differ depending on the types of wastewater and the sizes of wastewater treatment plants. Using the multi-variable linear regression method, correlations between OEFs and operating conditions, i.e. activities, from grit chambers were statistically analyzed. The analyses showed that operating conditions, including total suspended solids, water temperature, and temperature difference between water and air, were the most significant parameters affecting the OEF. A linear equation using these three parameters was proposed to estimate the OEF, and can be used to predict an OEF for another grit chamber, without odor measurement.

신경망 분석을 활용한 하수처리장 데이터 분석 기법 연구

서정식,김태욱,이해각,윤종호 한국환경과학회 2022 한국환경과학회지 Vol.31 No.7

With the introduction of the tele-monitoring system (TMS) in South Korea, monitoring of the concentration of pollutants discharged from nationwide water quality TMS attachments is possible. In addition, the Ministry of Environment is implementing a smart sewage system program that combines ICT technology with wastewater treatment plants. Thus, many institutions are adopting the automatic operation technique which uses process operation factors and TMS data of sewage treatment plants. As a part of the preliminary study, a multilayer perceptron (MLP) analysis method was applied to TMS data to identify predictability degree. TMS data were designated as independent variables, and each pollutant was considered as an independent variables. To verify the validity of the prediction, root mean square error analysis was conducted. TMS data from two public sewage treatment plants in Chungnam were used. The values of RMSE in SS, T-N, and COD predictions (excluding T-P) in treatment plant A showed an error range of 10%, and in the case of treatment plant B, all items showed an error exceeding 20%. If the total amount of data used MLP analysis increases, the predictability of MLP analysis is expected to increase further.