Biodegradation of lipidic compounds in synthetic food wastes during composting

Lemus, G.R. and Lau, A.K. 2002. Biodegradation of lipidic compounds in synthetic food wastes during composting. Canadian Biosystems Engineering/Le génie des biosystèmes au Canada 44: 6.336.39. Changes in food production, consumption patterns, and more restrictive regulations, result in larger quantities and higher diversity of waste materials that need to be treated and disposed. Organic wastes rich in lipidic compounds are not typically composted. However, fats, oils, and grease (FOGs) residues have a high-energy content that makes them ideal candidates for aerobic composting. The aim of this project was to evaluate the treatability and process performance of FOGs residues during composting. A series of preliminary tests was performed using canola oil as lipidic compound. The main substrate used was synthetic food waste (dry dog food). Thermophilic temperatures were readily achieved without any external heat addition with peak temperatures approximately 70°C. Results indicated that the thermophilic runs had an average lipid reduction of 70% with a maximum of 79%. However, change in volatile solids content was only 20% for the 10-day composting period. Cumulative heat generation ranged from 1.7 to 3.4 MJ for the thermophilic runs, which is one order of magnitude greater than the mesophilic runs (0.07 to 0.17 MJ). The contribution of lipids to heat was higher for the runs where canola oil was added.