최근 하수처리장의 질소 및 인 방류수 수질기준이 강화되고 슬러지의 해양투기가 금지됨에 따라 기존 표준활성슬러지공법의 고도처리공법으로의 증설 및 새로운 하수슬러지 처리공법에 대한 환경성, 경제성 평가의 필요성이 증가하고 있다. 이러한 고도처리 및 슬러지 처리공법은 운영 단계뿐만 아니라 건설, 폐기를 포함한 전과정에 걸쳐 환경 전반에 영향을 미치며 경제적 비용을 소모하므로, 본 연구에서는 건설에서부터 폐기까지의 전과정을 고려하여 고도처리공정 및 슬러지 처리 공법의 환경성, 경제성을 평가하고자 한다. 고도처리공법으로 Anaerobic/Anoxic/Oxic (A2O), Bamard Denitrification Phosphate (Bardenpho), Virginia Initiative Plant (VIP), Modified University of Cape Town (MUCT) 공법을,_x000D_ 슬러지 처리공법으로는 매립, 소각, 퇴비화를 선정하였다. 각 공법에 따른 환경성, 경제성 평가를 위하여 International organization for standardization (ISO)에서 제시하는 가이드라인을 따라 전과정평가를 수행하였으며, 전생애비용을 산정·비교하였다. 각 고도처리 공법에 대한 평가 결과, 환경영향 측면에서는 운영 단계에서의 생물학적 처리로 인한 온실가스 배출이, 경제성 측면에서는 운영 단계에서의 전력소모가 가장 많은 영향을 미치는 것으로 나타났다. 또한 가장 친환경적인 하수처리 및 슬러지 처리공법은 A2O 공법과 퇴비화로 환경에 가장 큰 영향을 미치는 CAS 공법과 매립에 비해 환경영향을 52% 줄일 수 있는 것으로 나타났다. 경제적인 측면에서는 가장 많은 비용을 소요하는 CAS 공법과 매립 적용 시에 비해 MUCT 공법과 퇴비화가 전생애비용을 62% 절약할 수 있음을 알 수 있었다. 본 연구를 통해 고도처리 공법으로의 증설 및 슬러지 처리에 대한 전과정을 고려하여 친환경적이며 경제적인 공법을 선정하기 위해 전과정평가를 수행하고 전생애비용을 산출하여 각 공법을 비교 및 평가하였으며, 전과정평가의 환경성 및 경제성에 중요한 영향인자를 분석하였다. 따라서 본 연구의 방법론을 통하여 환경부하 및 경비 절감을 고려한 고도처리공법의 개보수 공정 및 슬러지 공정 선택이 가능할 것으로 예상된다.

A lot of existing wastewater treatment plants (WWTPs) are rebuilt or retrofitted for advanced wastewater treatment processes to cope with reinforced effluent criteria of nitrogen and phosphorous. Moreover, how to treat the wasted sludge from WWTPs has been also issued since the discharge of the wasted sludge into ocean is impossible from 2011 due to the London Convention 97 protocol. These trend changes of WWTPs get a motivation to assess environmental_x000D_ and economic impacts from the construction stage to the waste stage in WWTPs. Therefore, this study focuses on evaluation of environmental and economic impacts of the advanced wastewater treatment processes and waste sludge treatment process by using life cycle assessment. Four advanced wastewater treatment processes of Anaerobic/Anoxic/Oxic (A2O), 5 stages-Bamard Denitrification Phosphate (Bardenpho), Virginia Initiative Plant (VIP) , and Modified University_x000D_ of Cape Town (MUCT) are chosen to compare the conventional activated sludge (CAS) and three waste sludge treatment methods of land fill, incineration, and composting are used. To evaluate environmental and economic impacts of each advanced wastewater treatment processes, life cycle assessment (LCA) and life cycle cost (LCC) are conducted based on International organization for standardization (ISO) guidelines. The results clearly represent that the A2O process with composting shows 52% reduction in the environmental impact than the CAS process with landfill. On the other hand, the MUCT process with composting is able to save 62% of the life cycle cost comparing with the CAS process with landfill. This result suggested the qualitative and quantitative criteria for evaluating eco-environmental and economic technologies of advanced treatment processes and also sludge treatment method, where their main influence_x000D_ factors on environmental and economic impacts are analyzed, respectively. The proposed method could be useful for selecting the most efficient and eco-friendly wastewater treatment process and sludge treatment method when retrofitting the existing WWTPs to advanced treatments.

Advanced Wastewater Treatment Sludge Treatment Life Cycle Assessment (LCA) Life Cycle Cost (LCC) Environmental Impact

Kim M, Yoo C, Korean Chem. Eng. Res., 46(3), 610 (2008)
Jung YL, “Application of LCA for the Operation Phase Between Standard Activated Sludge and A2O process,” Ph. M. thesis, the Univ. of Seoul, Korea (2007)
Oh TS, Kim MJ, Lim JJ, Kim YS, Yoo CK, Korean Chem. Eng. Res., 49(2), 187 (2011)
Zhou Z, Wu Z, Wang Z, Tang S, Gu G, Wang L, Wang Y, Xin Z, Korean J. Chem. Eng., 28(5), 1233 (2011)
Han JY, Cho HC, Kim DK, J. Korean Inst. Resource Recycling, 11, 17 (2002)
International Standards Organization, Environmental Management- Life Cycle Assessment- Principle and Frameworks, ISO 14040 (2006)
Small and Medium Business Administration, Green Management, http://www.greenbiz. go.kr/Ind01020000.action (2010)
Hong J, Hong J, Otaki M, Jolliet O, Waste Manage., 29, 696 (2009)
Pasqualino JC, Meneses M, Abella M, Castells F, Environ. Sci. Technol., 43, 3300 (2009)
Foley J, Haas DD, Hartley K, Lant P, Wat. Res., 44, 1654 (2010)
Kim MJ, Kim MH, Kim YS, Yoo CK, Korean Chem. Eng. Res., 48(5), 589 (2010)
IPCC, IPCC Guidelines for National Greenhouse Gas Inventories (2006)
Choi TH, “Waste Water Treatment Technology Using Adjuvants Coagulation,” Ph. M. thesis, Seoul National Univ. of Science and Technology, Korea (2011)
Thomsen M, Lyck E, Emission of CH4 and N2O from Wastewater Treatment Plants (6B), NERI Technical Note No.208, Ministry of the Environment, Denmark (2005)
Ristimaki M, Saynajoki A, Heinonen J, Junnila S, Energy, 63, 168 (2013)
Kloepffer W, Int J LCA, 13(2), 89 (2008)
Finkbeiner M, Schau EM, Lehmann A, Traverso M, Sustainability, 2(10), 3309 (2010)
Carlsson Reich M, Journal of Cleaner Production, 13, 253 (2005)
Lee JI, Lee KY, Yoo YS, Inhibition of waste oversea dump and project, Gyeonggi Research Institute (2013)
Lee HK, “The study of Change of Operating Factors with Traditional Activated Sludge and Attached Microorganism Process for the Nitrogen and Phosphorus Removal,” Ph. M. thesis, Seoul National Univ. of Science and Technology, Korea (2009)