Embodied water accounting and renewability assessment for ecological wastewater treatment

Abstract

For water accounting of wastewater treatment, existing studies focused on either direct water loss caused by evaporation/evapotranspiration by natural process or indirect water cost induced by economic inputs. As an extension of our previous work (Shao and Chen, 2013), both the direct and indirect water losses as embodied water are accounted for in the present study. A set of improved indicators have also been devised to assess the efficiency and renewability of wastewater treatment. After accounting and analyzing the embodied water of a pilot constructed wetland wastewater treatment system as an ecological engineering in Beijing, a comparison has been carried out between the case system and a traditional wastewater treatment plant based on the proposed indicators. The traditional wastewater treatment technology is illustrated however superior to the ecological way in terms of water use context. The present framework is capable of providing clear guidance for prioritizing options of wastewater treatment technologies by evaluating water trade-off, beyond the usual practice on treatment efficiencies and quality standards in effluents.