Chapter 8 - Life cycle assessment of wastewater treatment by microalgae

Abstract

Life cycle assessment (LCA) is a widely used tool for estimation of environmental footprint of any products, technologies, and services, throughout its whole life cycle from cradle to grave. It is a standardized decision support system, for quantifying the different environmental impact categories and deciding upon the sustainability of each system employed. The use of LCA tools for wastewater treatment and their impact assessment is started very recently. In wastewater treatment the LCA tools compile and evaluate the inputs and the outputs and consider their potential environmental impacts associated with the operation of the system for all types of wastewater treatment plants either for conventional or algal ponds, throughout its whole process chain. The LCA studies generally follow ISO standards (International Organization for Standardization) with baseline framework consisting of four phases, goal and scope determination, life cycle inventory analysis, life cycle impact assessment, and interpretation of results. The inventory analysis accumulates the data or the database for analysis, using specific criteria or data quality matrices and the impact assessment is carried out with the help of different types of softwares, namely, SimaPro, Gabi, OpenLCA, and Umberto. The impact assessment transforms the mathematical data to environmental effect equivalent via the factor multiplication. The LCA studies have validated that the wastewater treatment with microalgae comparing to the conventional can significantly reduce the negative environmental impacts, as well as the system has the advantage on low cost of operation, the possibility of recycling the nutrients in wastewater to high-value products, reducing the emissions by absorption of CO2 present in the flue gases and the discharge of oxygenated effluent into the water body.