A few days before Christmas I sang a variation of “Do You See (Smell) What I See (Smell)” to my wife as we walked through a store parking lot. The smell of residential organic waste composting was distinct! Which of the 350 different chemical compounds that have been measured at compost facilities was it? (e.g. Campbell and Gage).
Its easy to get overwhelmed by the different chemicals that may be in the air coming from compost facilities, with all their different characteristics. There have been some excellent reviews on odour at compost facilities (e.g. CIWMB 2007). We know that there are mixtures of compounds that give distinct “flavors”. Many conclude that odour is simply subjective, making it difficult to regulate.
Are there indicator compounds that are known to be offensive, and are known to be produced when the composting is not managed well? Yes, there are.
An understanding of the microbes in the compost pile, what they produce and under what conditions they produce them helps us to find these indicator compounds. We’ve known about these specific compounds for almost 100 years, and we’ve known that they are offensive. Our nose can smell some of these compounds in the parts per trillion concentration.
For mushroom composting, we know that hydrogen sulphide is an excellent indicator compound, and we can measure it at very low concentrations. This is because elemental sulphur is added to the process, and when the process or process water goes anaerobic, teh microbes produce hydrogen sulphide. We don’t have this luxury at compost facilities where commercial and residential organic waste is composted because sulphur concentrations are generally much lower and more variable than at mushroom compost facilities.
The Japanese have been processing organic waste much longer than we have in Canada. They have developed their Offensive Odor Control Law (Government of Japan 2003), which is very specific with some of the odour compounds. We know from research and experience in North America that we are dealing with some of the same offensive odour compounds that include butyric and valeric acids We also know that some of these key odour compounds are produced and emitted when the composting process is not well managed.
Others have learned how to manage these odours from the composting process (eg. Nordic Council 2009). In British Columbia, we can too. We will all have to accept that reducing odor to acceptable concentrations requires a commitment to process, which costs money. We need to work towards socially acceptable organic waste management. Its possible – even with meat waste.
CIWMB 2007. California Integrated Waste Management Board. Comprehensive Compost Odor Response Project. San Diego State University.
Campbell, J, and J. Gage. Undated. Characterization of odorous compounds at a composting facility. Columbia Analytical Services http://www.caslab.com/Forms-Downloads/Flyers/COMPOST_BROCHURE.pdf
Government of Japan. 2003. Offensive Odor Control Law in Japan. Office of Odor, Noise and Vibration Environmental Management Bureau Ministry of the Environment Government of Japan. https://www.env.go.jp/en/laws/air/offensive_odor/all.pdf
Nordic Council of Ministers, Nordic Council of Ministers Secretariat 2009. Minimisation of odour from composting of food waste through process optimisation: A Nordic collaboration project. http://norden.diva-portal.org/smash/get/diva2:702178/FULLTEXT01.pdf