Environmental Impact Assessment of Wastewater treatment plants to remove Nitrogen and Phosphorous from municipal wastewater: An application of Life Cycle Assessment Methodology

Abstract

Wastewater treatment plants are often required to increase the level of treatment to comply with stricter regulation on nutrients discharge, which typically requires increases in energy use, chemicals, and other material resources. Advanced treatment processes, while improving the water quality of the receiving water body, can also produce environmental and health impacts elsewhere in the technological life cycle, which need to be evaluated. Goal of the present study is to evaluate and compare those wastewater treatment technologies that have been specifically designed for nutrient removal, using Life Cycle Assessment (LCA) methods that cover a comprehensive set of environmental impact categories. Based on current and leading-edge advanced nutrient removal technologies, three different levels of treatments with a variety of nearly 30 treatment technologies and process scenarios are comprehensively evaluated and compared for environmental, economic and health impacts. æLCA analyses results show that, increasing treatment level from level 1 to level 3 significantly reduces the eutrophication potential as a result of the considerable reduction of nutrient discharges. Chemical and energy usage in highly-advanced treatments indirectly contribute to eutrophication as well. Interestingly, human health impacts and ecotoxicity potential increased as more advanced yet higher-energy-consuming technologies are applied. However, concomitant requirements and consumption of chemicals, energy and materials produce other negative impacts on the environment and human health that are not often considered in nutrient management and policy-making. Future work will include detailed modeling of sludge treatment and final disposal, as well as the effect of treatment level on contaminants of emerging concern.