Life-cycle assessment as an environmental management tool in the production of potable water.

The environmental life cycle assessment (LCA) methodology was used in this study to calculate and compare the environmental burdens resulting from two different methods employed in the production of potable water in South Africa. One method employs conventional processes for the treatment of water and the other one is based on membrane filtration. All inputs (raw materials and energy) and outputs (products, by-products and emissions to air, water and soil) from the two methods were listed and quantified. These inputs and outputs cause different environmental impacts (global warming, ozone depletion, smog formation, acidification, nutrient enrichment, ecotoxicity and human toxicity) and the contribution of each method to each of these impact categories has been quantified, resulting in a score. The ISO (International Organisation for Standardisation) methodological framework for life cycle assessments guided this study. By using these methodologies and by tracing all the processes involved in the production of potable water to the interface with the environment, it was found that the main contributor to the overall environmental burden is the generation of electricity. This conclusion is valid for both methods investigated and in order to increase the environmental performance in the production of potable water the energy efficiency of waterworks should be increased.