Sustainable solutions for organic waste management: nitrogen emission reduction in parallel with greenhouse gases

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Ammonia volatilization is a major atmospheric pollutant resulting in the deposition of nitrogen at rates in locations affecting aquatic ecosystems, soil carbon dioxide emissions and sensitive crops. Over 70% of ammonia emissions originate from organic waste management, especially livestock manures. In the future, more food waste composting will increase ammonia volatilization. Anaerobic digestion is a solution but producer commitment is required for a clean source of food waste. Along with past technologies developed to sustainably manage organic wastes and wastewaters, the aim of the present research is to introduce systems attenuating ammonia volatilization. More specifically, the proposed research will further develop a feasible system, In-Storage-Anaerobic-Digestion (ISPAD), reducing greenhouse gas, odour and ammonia emissions from wastewaters stored over 100 days such as livestock manures. The research will develop an acidifying method for the manures retained in ISPAD such that, once removed for land spreading, ammonia volatilization is limited. The research will: establish the equilibrium constant between ammonium and ammonia in swine manures, as a function of temperature and pH, because this constant differs from that of water; then, measure swine manure buffer capacity (resistance to acidification) and its variability depending on the animal feed used; then, find how much buffering capacity is removed with various manure treatments, including lowering ammonium levels; finally, test ISPAD conditions required to adequately acidify the treated manure. In parallel, an ammonium recovery system can be developed to produce fertilizers. In addition to ISPAD, it is proposed to initiate the development of a system for the clean source separation of food waste with minimum producer effort. Also, strategies to reduce ammonia volatilization from compost will be pursued. The significance of the proposed research is to reduce ammonia emissions in Canada by 50%, and to extend this technology to the world, such as Europe where N deposition is also a major concern. If transformed into fertilizers, this nitrogen conservation can drop by 6-7% of the use of natural gas in North America and Europe.