Using site-specific life cycle assessment methodology to evaluate Chinese wastewater treatment scenarios: A comparative study of site-generic and site-specific methods

This study was conducted to investigate whether the environmental impact assessment of wastewater treatment plants (WWTPs) varies with different life cycle assessment (LCA) methods. A full-scale WWTP in China was investigated in this LCA analysis using a generic LCA method, CML, and a China-specific method, e-Balance. Specifically, environmental impact were examined and compared for four effluent treatment levels: no treatment, basic treatment, intermediate treatment and tertiary treatment. The results revealed great variation between the no treatment scenarios and between the tertiary treatment scenarios. The inclusion or exclusion of chemical oxygen demand (COD) as an independent impact category was identified as the main reason for the disparate results with respect to the no treatment scenarios. The absence of toxicity-based impact categories in the database associated with e-Balance method resulted in the lower environmental impact assessment for tertiary treatment scenario of e-Balance than CML method. We concluded that site-generic LCA methods might generate outcome bias when evaluating cases with obvious regional features, and that regionalized LCA methods are needed to deal with cases having an obvious impact on the regional environment.