Environmental performance of an innovative waste refinery based on enzymatic treatment

Decrease of fossil fuel dependence and global warming mitigation has become increasingly important issues during the last decades. With respect to waste management higher recycling rates for valuable materials as well as energy recovery from waste streams could play a significant role substituting for virgin material and saving fossil resources. In this paper a life-cycle assessment of a pilot-scale waste refinery for the enzymatic treatment of municipal solid waste (MSW) is presented. The refinery produced a liquid (liquefied organic materials and paper) and a solid fraction (non-degradable materials) from the waste. The waste refinery was compared to alternative treatments such as incineration, bioreactor landfill and mechanical-biological treatment followed by utilization of the RDF (refuse-derived fuel) for energy. The performance of the waste refinery turned out to be comparable with incineration for most environmental categories. Landfilling turned out to be the worst option with respect to most categories (especially energy-related such as GW). The refinery treatment has large margins of improvement with respect to the environmental performance. These are mainly associated with the opportunity for decreases in heat and enzyme consumption.