Life-Cycle Assessment of Tertiary Treatment Technologies to Treat Secondary Municipal Wastewater for Reuse in Agricultural Irrigation, Artificial Recharge of Groundwater, and Industrial Usages

Abstract

Life-cycle assessment (LCA) was applied to assess the environmental impacts of a wastewater treatment plant (WWTP), along with 20 tertiary treatment options for reuse in agricultural irrigation, artificial recharge of groundwater, and industrial usages. Impact 2002+ was adopted as the life-cycle impact assessment method. The results indicate that the energy consumed by the equipment accounts for 66.59% of environmental impacts of the WWTP. Moreover, consumption of the electricity generated by local biogas generators, instead of using the Iranian national grid, can be beneficial in mitigating the environmental impacts of the WWTP in the form of avoided impacts. LCA showed that a depth filter, granular activated carbon, and chlorination; a membrane bioreactor and chlorination; ultrafiltration, reverse osmosis, and chlorination; and ultrafiltration, reverse osmosis, a depth filter, coagulation/flocculation, and chlorination had the lowest environmental impacts for reuse in agricultural irrigation, artificial recharge of groundwater, cooling towers and other industries, and boilers, respectively. Energy consumption of tertiary treatment technologies is the primary contributor to the environmental impacts. This study indicated that because of high electricity and chemical consumption of the options for reuse in industries, their environmental impacts are higher than those of other options.