Energy Saving Analysis at Sewage Treatment Plants - A Case Study in China -

The need to save energy at sewage treatment plants is a common issue in Japan and China. We applied a sewage treatment plant performance evaluation system to study the energy-saving effects and effluent water quality by studying values of the control parameters. The evaluation system is a simulator applicable to the sewage treatment plant process as a whole. It performs an overall evaluation of effluent water quality and energy consumption by linking water treatment with sludge treatment. Analysis was made of two medium-sized plants with a treatment capacity of 10,000 m3/day and one large treatment plant with a capacity of 150,000 m3/day. We studied the control settings for MLSS, return sludge ratio, and reactor DO. The analysis indicated that power consumption could be reduced by 7 to 17%.