Adopting Low-GHG Emission Wastewater Treatment Technologies is Key to Climate Change Mitigation

The municipal water treatment sector is Ontario’s largest energy consumer (34%), which accounts for 2.88 TWh of electricity, equivalent to 0.58 Mt CO2e. The wastewater treatment plants (WWTPs) in Ontario represent 46% of this emission portfolio (0.27 Mt CO2e). Thus, the Ontario WWTPs can significantly contribute to Canada’s climate action goal by lowering their carbon footprint. 

With that mindset, Dr. Rania Hamza and her colleagues are assessing the energy requirement and reliability level of different wastewater technologies in small communities across Ontario by partnering with the Ontario Clean Water Agency and Hannah Environmental Equipment Inc. This research aims to quantify and mitigate the energy consumption (and GHG emission) in the municipal wastewater treatment sector without sacrificing reliability.

Dr. Hamza’s team analyzed five different treatment technologies, namely, rotating biological contactor (RBC), sequencing batch reactor (SBR), membrane bioreactor (MBR), lagoon, and extended aeration activated sludge process, from the historical performance data of eight different WWTPs in southern Ontario and used four key performance indicators (KPIs) for the energy benchmarking. Among the tested treatment technologies, the rotating biological contactor (RBC) method consumed the least energy while the sequencing batch reactor (SBR) was the most energy extensive. The study also pointed out that regular maintenance of RBC units (e.g., routine sludge removal) is crucial to meet regulatory requirements and scale-up as a low-energy water treatment option. The experiential learning from this project provided an in-depth view of the water-energy nexus in Ontario and highlighted the opportunities of climate-focused research in the wastewater sector.