Urban wastewater reclamation for industrial reuse: An LCA case study

Water scarcity is one of the major problems of the 21st century and one of the most sensitive environmental issues in the coming decades due to the uneven distribution of resources, treatment and climate change events. Wastewater reclamation is considered as an alternative source of fresh water in areas with problems of water availability or increased consumption. The objective of this study is to use Life Cycle Assessment (LCA) methodology to identify and quantify the main environmental contributors derived from the treatment of urban wastewater and water reclamation opportunities in Tarragona, Spain. The wastewater treatment plant (WWTP) serves a population of about 150,000 inhabitants and has mechanical and biological treatment for the wastewater line and sludge processing. The primary data correspond to 2014, when 27,000 m(3)/d of wastewater from urban collectors and rainwater were treated. Two scenarios are considered after the conventional treatment in the WWTP: a) direct discharge into a natural water stream and b) introduction of the tertiary treatment to facilitate water reuse in the nearby industrial area. This study showed that the tertiary treatment contributes significantly to the environmental impacts. The category with the highest value is the cumulative energy demand (5.44 MJ-Eq) due to the large amount of energy required for the advanced treatment stages needed for reuse. The results showed also that in the case of the "water reuse" scenario the indicator water depletion (WD) is - 4.39.10(-1) m(3) per m(3) of wastewater treated in Tarragona as compared with 5.74.10(-4) m(3) in the case of "no reuse" option. From a comparison of these alternatives it may be observed that in the case of the reuse scenario the value is negative which means that there is a net saving of water from nature. This indicator represents a measurement in a life cycle perspective of the effect of wastewater reuse in Spain, the non-potable use of reclaimed water reducing the stress on fresh water supplies. (C) 2016 Elsevier Ltd. All rights reserved.