The Trade-off Between Environmental Impacts in Water Recycling Systems Using Industrial Effluent

A life cycle assessment was conducted on three industrial effluent water recycling options using a one-, two-, and three-stage effluent treatment plant composed of clarification, aerobic treatment, and ultrafiltration processes. The impact categories dominated by energy use and the category of freshwater use were then further investigated and compared between each recycling system. A dual functional unit of recycled water delivered and effluent treated was identified to make the recycling options functionally equivalent. Three-stage water recycling was the environmentally preferred option, with all three water recycling options investigated producing similar environmental impacts in most impact categories, with the exception of freshwater use, where the one-and two-stage treatment options performed significantly worse than the three-stage treatment. It was found that the impact categories of global warming potential and nonrenewable energy demand did not directly correlate with each other as a result of direct greenhouse gas emissions from sludge disposal. The construction of the equivalent systems shows that external systems required for functional equivalence are important in water recycling comparisons, and considering dual functional units is important for comparing water recycling options. With the increasing prevalence of industries utilizing biomass and other renewable fuels, it is becoming more apparent that measuring energy usage is not sufficient, and the specific impacts and damages associated with energy consumption need to be evaluated. This study provides a framework to identify opportunities in industrial wastewater management, which can be particularly important in industries with large effluent flows and high organic loadings.