Life-Cycle Assessment of Wastewater Treatment Plants

This thesis presents a general model for the carbon footprints analysis of wastewater treatment plants (WWTPs), using a life cycle assessment (LCA) approach. In previous research, the issue of global warming is often related to traditional industries with high carbon dioxide (C0 2) emissions, such as power plants and transportation. However, the analyses of wastewater treatment plants (WWTPs) have drawn increasing attention, due to the intensive greenhouse gas emissions (GHG) from WWTPs. WWTPs have been listed in the 7 th place for both methane (CH 4) and nitrous oxide (N2 0) total emissions. In addition, WWTPs indirectly contribute to a huge amount of CO 2 emissions. The final results have shown that more than half of the carbon footprints from the La Gavia WWTP are from the indirect emissions of C0 2, which is caused by the intensive energy consumption. The direct emissions of CH4 and N 20 combined contribute more than 30 percent of GHG emission. The finally section of the thesis compares the environmental impacts of the La Gavia WWTP with case of no WWTP at all. It has been concluded that although the La Gavia WWTP increased the total carbon footprints, it has much better control of eutrophication potential (EP). Thesis Supervisor: Eric Adams Title: Senior Research Engineer and Lecturer of Civil and Environmental Engineering ACKNOWLEDGEMENT I would like to thank everyone who has helped me or encouraged me during my study in the M.Eng program. This thesis would not have been possible without your support. First of all, I would like to express my deepest appreciation to my parents. Thank you for your continuous encouragement and financial support. Without you, I wouldn't make through those tough days. I want to thank my supervisor, Dr. Eric Adams, for giving me patient guidance and valuable advice during the entire project. I want to thank my fellow M.Eng classmates, who made my life at MIT more unforgettable. You are amazing. Special thanks for my Spain team members, Xin Xu and Jong Lim. Our LDX Environmental is the best. I want to thank Dr. Pete Shanahan, Dr. Windsor Sung, and Angela Schindler for giving me continuous support for the project. Last but not least, I would like to thank Emma Montes Parra and Gloria Garralon Lafuente from Cadagua S.A. for allowing us to visit Spain. CONTENTS ACKNOW LEDGEM ENT............................................................................................................... 3 LIST OF TABLES .......................................................................................................................... 6 LIST OF FIGURES......................................................................................................................... 7