Application of bridle model in estimating greenhouse gases emissions from three wastewater treatment plants in Fukushima Prefecture, Japan

Abstract

The estimation of Green House Gases (GHGs) plays an important role in reducing emissions to prevent global warming and climate change. The Intergovernmental Panel on Climate Change (IPCC) method is the most commonly used in estimating the emissions from a wastewater treatment plant (WWTP). However, it is difficult to establish technical strategies in emissions reduction as the method cannot identify which treatment unit contributes to the total emission. In this study, we estimated GHGs from WWTPs using the Bridal Model based on the operations and processes in each treatment plant unit. We applied the model to three WWTPs located in Fukushima, Koriyama, and Nihonmatsu City, Japan. The results were evaluated by comparisons with those estimated by the IPCC method. The bridle model results showed that the average daily GHG emissions in Fukushima, Koriyama, and Nihonmatsu in the 2015-2018 period were 86.4, 55.2 and 6.2 ton CO₂ eq/day. Furthermore, emissions from the three WWTPS per m³ of treated wastewater were insignificantly different from those estimated by the IPCC method. Sludge treatment was the most sensitive treatment unit as it contributes to 31.8-70.3% of the total emission, followed by chemical and biological treatment units. The study suggests that utilizing biogases produced from the sludge treatment could reduce 21.4-49% of total emissions from a WWTP.