Life cycle assesment for a large scale water treatment plant

Water is the main living source and it is very important to protect and serve drinkable water to each person. Overpopulation and unprotected water sources result in lack of drinkable water. Therefore, sustainability of water treatment plants should be taken in the consideration. Istanbul is the most crowded industrial city in Turkey. Because of that, the main objective of this work is to evaluate the environmental impact of a large scale water treatment plant in İstanbul. In this study, environmental impact of Kağıthane Water Treatment Plant (KWTP) is evaluated by life cycle assesment approach. KWTP is one of the biggest water treatment plant in the western side of Istanbul and the plant take raw water from Terkos Lake and Alibey dam. KSAT include two water treatment plants which are constructed in different years. While Kağıthane Yıldırım Bayezid Water Treatment Plant (KYBWTP) is operated, the Kağıthane Çelebi Mehmet Water Treatment Plant (KÇMWTP) is constructed because of increasing water demand. After determination of system function and functional unit of water treatment system, data inventory analysis of plant was done for one year. The material usage, electricity consumption and transportation was normalized per 1 m3 of potable water. The system boundary of the plant includes main and sub treatment processes. The main processes in the plant are the screen, input/output pumps, aeration, ozonation, slow/rapid mixing, clarification, filtration, disinfection, reservoir and sludge transportation. The sub processes are chemical units, backwash water, blower, sludge pump unit and clarified water pump unit. GaBi 7.3 software is applied as tool of life cycle assessment approach. The processes and flows are made up in GaBi 7.3 software depending on the system boundary of water treatment plant. LCA approach is the main guide while collecting required inputs and outputs of each process. GaBi 7.3 software is normalized all data entry and balances it. Environmental impact categories which are available in this software have acquired by the available methods. In this study, the Centre for Environmental Studies (CML 2001) method has been selected to evaluate the environmental effects and the results are interpreted according to the goal of study. The impacts categories are evaluated by GaBi software in terms of Global Warming Potential (GWP), Acidification Potential (AP), Eutrophication Potential (EP), Ozone Layer Depletion Potential (ODP), Abiotic Depletion Potential (ADP elements), Abiotic Depletion Potential (ADP fossil), Freshwater Aquatic Ecotoxicity Potential (FAEP), Human Toxicity Potential (HTP), Marine Aquatic Ecotoxicity Potential (MAEP), Photochemical Ozone Creation Potential (POCP), Terrestric Ecotoxicity Potential (TETP). The environmental impacts of the investigated water treatment plant accordant to the literature values. The highest shares to GWP, EP, ADP Fossil, HTP, MAEP and TETP come from output pumps and input pumps. The main contribution to AP, FAEP and POCP is because of output pumps, input pumps, orifices and distribution unit. Moreover, distribution ünite, orifices and disinfection are the significant share in OTP. The main contributor of ADP Element is the input pumps, output pumps and disinfection. In this study, three environmental impact assessments which are KÇMWTP, KYBWTP and KWTP has been applied and those have been compared. The results have smarties and differences based on environmental impact categories. The similarities are due to more environmental impacts of the common treatment units which are output pumps, input pumps and ozonation. The differences are due to more environmental impacts of the uncommon treatment technologies which are the coagulation-flocculation and sedimentation. The environmental impacts have compared with the one of the main water treatment plant in Istanbul and literature results. The reason of similarities and differences has been interpreted. The results show that electricity consumption is the main reason of environmental impact. Kağıthane Water Treatment Plant has consumed the Turkey electricity source and impact assessment has been performed by that. Moreover, the environmental impacts have compared with a case study which is based on the consumption of European electricity source. All environmental impacts are more in case of European electricity source consumption except KIP.