Benchmarking energy consumption in municipal wastewater treatment plants in Japan

Abstract

Reduction of greenhouse gas (GHG) emissions is one of the most important tasks facing municipal WWTPs. Electric power consumption typically accounts for about 90% of the total energy consumption. This study presents a benchmarking analysis of electric power consumption. The specific power consumption (SPC) ranged from 0.44 to 2.07 kWh/m(3) for oxidation ditch plants and from 0.30 to 1.89 kWh/m(3) for conventional activated sludge plants without sludge incineration. Observed differences of the SPC can be attributed to the difference in the scale of plants rather than to different kinds of wastewater treatment processes. It was concluded that economical benefits by centralizing treatment had contributed significantly to the reduction of energy consumption. Further analysis was carried out on the plant that had shown an extremely small SPC value of 0.32 kWh/m(3). In this WWTP, a large amount of digestion gas was generated by anaerobic digestion. In particular, it was used to generate power using phosphoric acid fuel cells to generate approximately 50% of the energy consumed in the plant. It was calculated that this plant had reduced the overall SPC by 0.17 kWh/m(3). The effect of power generation using digestion gas demonstrated clearly the advantage of implementing energy recovery schemes.

Water-energy nexus for urban water systems: A comparative review on energy intensity and environmental impacts in relation to global water risks

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Pilot scale application of anaerobic baffled reactor for biologically enhanced primary treatment of raw municipal wastewater

“…Approximately half of influent carbon is converted into fast growing microbiota, and the remaining half is released to the atmosphere through the generation of CO 2 . One of the largest operational costs in wastewater treatment is electricity, and almost half of a treatment plant's entire energy demand is used for aeration (Mizuta and Shimada, 2010). The current emphasis on aerobic biological treatment wastes much of the energy value of the organic matter and maximizes the production of biosolids.…”

A Critical Review on Processes and Energy Profile of the Australian Meat Processing Industry

“…Upper and lower estimates for energy intensities for technologies such as desalination and wastewater reuse are provided. Compare to the CAS system, oxidation ditch (OD) treatment systems have higher energy demands of 0.5-1.0 in Australia, 0.302 in China, or 0.43-2.07 kWh/m 3 in Japan because of longer hydraulic retention time (HRT) and higher energy consumption for higher specific-oxygen demand [84,88,89].…”