Benchmarking energy consumption in municipal wastewater treatment plants in Japan

摘要

Reduction of greenhouse gas (GHG) emissions is one of the most important tasks facing municipalnWWTPs. Electric power consumption typically accounts for about 90% of the total energynconsumption. This study presents a benchmarking analysis of electric power consumption. Thenspecific power consumption (SPC) ranged from 0.44 to 2.07 kWh/m3nfor oxidation ditch plants andnfrom 0.30 to 1.89 kWh/m3nfor conventional activated sludge plants without sludge incineration.nObserved differences of the SPC can be attributed to the difference in the scale of plants rathernthan to different kinds of wastewater treatment processes. It was concluded that economicalnbenefits by centralizing treatment had contributed significantly to the reduction of energynconsumption. Further analysis was carried out on the plant that had shown an extremely smallnSPC value of 0.32 kWh/m3n. In this WWTP, a large amount of digestion gas was generated bynanaerobic digestion. In particular, it was used to generate power using phosphoric acid fuel cellsnto generate approximately 50% of the energy consumed in the plant. It was calculated that thisnplant had reduced the overall SPC by 0.17 kWh/m3n. The effect of power generation usingndigestion gas demonstrated clearly the advantage of implementing energy recovery schemes.