Environmental analysis of chemicals and energy consumption in water treatment plants: case study of Oslo, Norway

This paper studies the trend in the consumption of energy and chemicals and the associated environmental impacts, for water treatment plants (WTPs) in Oslo, over the years between 2000 and 2009. The Norwegian Drinking Water Regulations stipulate that supplied water should comply with over 50 quality criteria. Abiding by the regulations and improving the water quality has its costs – economically and environmentally. Quality improvement entails, inter alia, the consumption of more chemicals, both in terms of quantity and variety, and a rise in energy consumption. In order to determine the environmental impacts of the consumption of chemicals and energy, an environmental life cycle assessment (LCA) was carried out. It was observed that the impacts of chemicals have increased dramatically after 2007, courtesy of a process upgrading at one of the WTPs. Except in the years 2004 and 2007, the impacts attributable to chemicals consumption have exceeded those due to energy consumption. Global warming is the key impact in both cases, though in the case of energy consumption, abiotic depletion and acidification are also significant.