Anaerobic biodigestion for enhanced bioenergy generation in ethanol biorefineries: Understanding the potentials of vinasse as a biofuel

Abstract

The application of anaerobic digestion (AD) as a core treatment technology in industrial plants concentrates important advantages on an environmental and energetic basis, associating wastewater pollution control with bioenergy generation from biogas. Vinasses from ethanol production are characterized as suitable effluents for AD, as high levels of easily degradable organic matter are usually found in such streams. A detailed energetic assessment indicated that bioenergy generation from biogas could fully supply sugarcane-based ethanol plants, whereas for corn- and cassava-based processes reductions of about 30%-35% in the total fossil energy consumption could be achieved. Particularly, the recovered energy from biogas could enhance the energy balance ratio of ethanol production by over 30% in ethanol production from corn and cassava. Specific economic assessments confirmed the economic feasibility of implementing AD systems in large-scale sugarcane-based distilleries, with annual revenues from electricity sales reaching over 10 USD million for both autonomous and annexed plants.