As urbanised regions are growing rapidly, food waste generation is growing proportionately. Globally in the last years, around 1/3 of food produced is being wasted. North American and Oceania countries waste 42% of food in the food chain production, with a substantial part of it (61%) discarded at the consumption stage. Most of this waste is organic and it is typically disposed and treated in the landfills, where anaerobic decomposition contributes 13% of anthropogenic methane and 7% of all methane emissions. Since methane is a greenhouse gas which traps 34 times more heat than carbon dioxide, its release from the landfills is contributing to global warming and one mitigation strategy would be to divert organic waste from landfills to other treatment strategies.
Composting is an aerobic, biological decomposition process, which can treat organic wastes of a specific carbon:nitrogen balance (~20-30:1) to produce a stable nutrient rich material suitable for addition to soil. The traditional field windrow process takes around three months to produce stable compost, but a more modern in-vessel composting system employs process control, which can produce stable compost in ~2-3 weeks or in some cases, according to the manufacturers, in 24 hr. Compost applied to soil can improve its physical, chemical and biological characteristics, and contribute to long-term carbon sequestration and to greenhouse gas reduction. There are additional positive impacts in the social (community engagement) and economic (profits for new businesses) spheres.
Our research uses onsite in-vessel composting to explore process performance in terms of stability, quality and safety of the final product. As baseline data generation, 5 x 24 hr composting experiments with a 20 L commercial in-vessel composter were carried out. Physical and chemical parameters have been determined and microbial communities within the compost bed are being assessed. Our goal is to optimise the composting process to allow production of high quality compost, free of pathogens.