The environmental sustainability evaluation of an urban tap water treatment plant based on emergy

The resources and environment issues, derived from tap water production, have been widely concerned with fast development of social economy. Based on the characteristics of water supply systems (especially its pollution emissions' impact), this work proposed a set of improved indicator system for evaluating their environmental sustainability. As a case study, a tap water treatment plant, located in Jiangsu Province, China, was investigated using the proposed indicator system. The study results show that (1) purchased nonrenewable input accounts for 50.24% of the total input; therein, thermal power contributes the largest; (2) the unit emergy value of tap water reaches 9.03E11sej/m3 based on the baseline 12.0E24 Sej/a; (3) the Mn removal needs the largest cost in terms of emergy; (4) the pollution emissions' impact reduces its performances slightly; (5) based on the classic indicator values, it has better economic benefit, lower environmental loading, and higher sustainability level than the similar systems. After some issues' discussions, this work puts forward the related suggestions for further improving its comprehensive performance in the future.