Energy Efficiency and Influencing Factors of Wastewater Treatment Plants in Yangtze River Economic Belt

Abstract:

The energy efficiency indicators of 970 WWTPs in the Yangtze River Economic Belt （YREB） were evaluated， including the energy intensity （EI） via normalization and the relative energy efficiency （REE） via data envelopment analysis. Meanwhile， influencing factors of designing， operational conditions， and externalities were analyzed. The results show that the EIs of 970 WWTPs change from 0.10 to 1.84 kWh·m^－3 and from 0.41 to 1.42 kWh·kg^-1 in terms of wastewater treated and COD removed， while the variation range of REE is 0.02~2.35. The impact of scale effect on energy efficiency is significant. The WWTPs configured with activated sludge-based processes tend to own better performance on energy efficiency. Besides， relatively higher pollutant concentrations in influent and less strict discharge standards would facilitate the energy efficiency. Finally， WWTPs in subregions of upstream， midstream， and downstream in YREB have different energy efficiency situations. This phenomenon is resulted from the factors such as designing factors， operational conditions， and externalities of WWTPs. This paper is expected to provide theoretical basis and technical support for energy-saving and emission-reduction of WWTPs.

Key words:wastewater treatment plants;energy efficiency indicator;Yangtze River Economic Belt;data envelopment analysis