Household food waste to wastewater or to solid waste? That is the question.

Decision makers need sound analyses of economic and environmental impacts of options for managing household food waste. Food waste impacts public health (it rots, smells, and attracts rodents) and costs (it drives collection frequency). A life cycle inventory is used to quantify total materials, energy, costs and environmental flows for three municipal solid waste systems (collection followed by compost, waste-to-energy or landfill) and two wastewater systems (kitchen food waste disposer followed by rural on-site or municipal wastewater treatment) for food waste management. Inventory parameters are expressed per 100 kg of food waste (wet weight) to place data on a normalised basis for comparison. System boundaries include acquisition, use and decommissioning. Parameters include inputs (land, materials, water) and output emissions to air, water and land. Parameters are ranked simply from high to low. Ranking highest overall was the rural wastewater system, which has a high amount of food waste and carrier water relative to the total throughput over its design life. Waste-to-energy was second; burning food waste yields little exportable energy and is costly. Next, municipal wastewater tied with landfill. Municipal wastewater is low for land, material, energy and cost, but is highest for food waste by-product (sludge). Landfill ranks low for air emissions and cost. Compost ranks lowest; it has the lowest material and water inputs and generates the least wastewater and waterborne waste.