Keywords: agrifood waste, anaerobic digestion, global warming, agroindustrial waste, Spain, tomato residue, slaughterhouse waste, waste generation rates, methane, carbon dioxide, CO2, biogas, electricity generation, carbon emissions, environmental benefits, energetic benefits
Environmental and energetic benefits derived from the anaerobic digestion of agroindustrial wastes
Agrifood industry plays a relevant role in the economic development of the autonomous community of Extremadura (Spain), and generates vast volumes of wastes featured by both high polluting potential and moisture content. The present work reports on a detailed analysis of biogas generation from the anaerobic digestion of industrial tomato residues and slaughterhouse wastes, in this way, yields achieved by treating the optimal flow has been 9.68 and 17.84 Nm³ methane/m³ substrate respectively. To determine the environmental and energetic benefits of anaerobic digestion, the annual waste generation rates in Extremadura were taken as input data; the methane and carbon dioxide volumes per ton waste were assumed as those of the hypothetical case of wastes being naturally decomposed; and the obtained biogas was regarded to serve as fuel for useful energy production (heat and/or electricity). Under these assumptions, the environmental benefit of the anaerobic digestion of the wastes was quantified and compared with the greenhouse emissions that might be observed if such wastes were directly dumped to the environment. If the analysed wastes were treated by anaerobic digestion, it would generate 50.9 GWh of electricity and prevent the emission of almost 204,000 equivalent tons of carbon dioxide annually.