A study on the Environmental Efficiency Improvement of a Sewage Treatment Plant by Performance Evaluation System

We developed the Performance Evaluation System (PES) which evaluates both items on water quality in effluent and energy consumption by using the data of water quantity and water quality for whole processes in a sewage treatment plant. PES can calculate water quality in effluent and energy consumption quantitatively by using unit process models and evaluate the effect of the advancement of the operating management in whole integrative treatment processes. We examine the reconstruction to aim advanced treatment processes and energy recovery from the viewpoint of both water purification and energy consumption on model sewage treatment plant with the capacity of 48000m3/day. It's achieved not only the improvement of water quality in effluent but also the reduction of excess sludge which needs more energy consumption and costs followed by additional treatment. About the nitrogen removal, MVNR (Marginal value of energy for Nitrogen removal) is able to estimate both water quality in effluent and energy consumption Anaerobic digestion and digestion gas generation for energy recovery in the sewage treatment plant are examined by EIR(Energy independence ratio) and EEIR(Electric Energy independence ratio). It is expected that EIR will be 37.1% and EEIR will be 41.8% with the application of solubilization facilities and increment of inflow BOD.