Evaluation of a Hybrid Approach of Food Waste Management

Abstract. Food waste is one of the largest component of municipal solid waste (MSW) in Canada and USA. About 30%-50% of global produced food becomes waste and this value is around 40% in North America. On average a Canadian produces almost 300 kg food waste annually and half of it is collected separately from individual households which needs immediate treatment. In majority of the cities and municipalities in North America (especially in USA) the food waste is collected and disposed in a MSW landfill. There has been recent trends in many cities and municipalities in North America including Ontario is to collect the food waste as part of source separated organics (SSO) and treat and manage the SSO using either compost plants (aerobic process) or as part of an anaerobic digestion (AD) plants with composting treatment being a dominant one. Both these approaches have their benefits and drawbacks. In very recent, there has been discussions in the waste related symposiums and conferences has been to use a hybrid approach, which is to separately collect the readily degradable food waste and treat them in an AD system to capture the methane gas and use it as an energy source and use the AD solid digestate along with other organic wastes to produce a good quality compost to recover nutrient value and use it as the soil amendment. For evaluation of this hybrid approach, a laboratory scale wet mesophilc type AD treatment of food waste was considered to determine optimum operational conditions for maximum energy recovery from food waste streams. In addition, the AD solid digestate composting was evaluated mixing with other organic waste to produce good quality compost. A batch scale continuous stirred-tank reactor (CSTR) type food waste AD for biogas production in the laboratory at mesophilic temperature can determine the optimum production parameters. An existing southwest Ontario food waste AD facility was evaluated for this AD reactor. Food waste characterization and pre-treatment can be carried out at AD plant and the laboratory set up condition can be same as the existing food waste AD plant. A windrow composting process activities can be monitored and evaluated from the same city composting facility. AD solid digestate co-compost in this compost plant was evaluated. Temperature, PH, C/N ratio, moisture content and produced gases from AD and other parameters along with aerobic composting parameters were considered same as the existing facility. Finally this hybrid approach was compared with the existing systems in an Ontario city e.g., Greater Toronto (GTA) AD and composting facility.