Population growth in Canada has resulted in a significant increase in the amount of organic waste. Canada produced over 25 million tons of waste in 2014, with 64% sent to landfills. Landfills, the most common way of disposing waste, are a major source of methane gas. Methane is 21 times more potent than carbon dioxide in terms of its global warming potential. Emissions from Canadian landfills account for 20% of national methane emissions. Anaerobic digestion, a microbial process occurring in the absence of oxygen, offers a method to divert waste from and treat waste in landfills. In addition to treating waste,anaerobic digestion produces biogas that can be used as an energy source. Anaerobic digestion is a multi-step process where each step is carried out by different types of microbes. As microbes are living things like us, they too have favourite foods, temperatures to live in, and friends to hang out with. Therefore, understanding the conditions that the microbes prefer is crucial for optimal performance of the anaerobic digester. Nigel Guilford, a Ph.D. candidate in Dr. Edwards’ lab, has designed a novel waste digestion apparatus, that can treat waste and produce biogas. Nigel has been studying the digester’s optimal operating conditions and limits. Another graduate student, Peter Lee, is identifying the types of microorganisms living in the digester and how they perform as they are fed diets of different wastes and change the operating environment. So far, Nigel and Peter have identified optimal operating conditions for the digester and the number of microbes operating in the system. Further investigation is being done to identify the microbes present by studying their DNA.
This study has helped us understand the operating limits and parameters of the anaerobic digestion process and the characteristics and behaviour of the digester’s microbial community. This knowledge will be used to design an optimized scaled-up digester for the municipality level that can decrease the volume of waste sent to landfills and reduce the amount of methane emitted into the environment.
By Peter Lee,