Energy-environmental benefits and economic feasibility of anaerobic codigestion of Iberian pig slaughterhouse and tomato industry wastes in Extremadura (Spain)

► Methanization of Iberian pig slaughterhouse and tomato industry wastes is studied. ► Influence of the composition of the substrate in methane yield has been analyzed. ► Optimum percentage of both substrates is determined by codigestion experiments. ► Environmental and energetic benefits of anaerobic codigestion are quantified. ► The results obtained prove that anaerobic digestion is economically profitable. Anaerobic digestion of Iberian pig slaughterhouse and tomato industry wastes, as well as codigestion operations from such residues, are reported to achieve 54–80% reduction in Chemical Oxygen Demand and 6–19Nm3/m3 substrate methane production. Furthermore, 0.79–0.88m3water/m3 substrate is seen to be recovered after the above mentioned operations, which might be used as irrigation water, and 0.12–0.21m3agricultural amendment/m3 substrate with 91–98% moisture content. The present paper also reports on the economic feasibility of both an anaerobic codigestion plant operating with 60% slaughterhouse wastes/40% tomato industry wastes (optimal ratio obtained in previous laboratory-scaled experiments), and an anaerobic digestion plant for Iberian pig slaughterhouse waste. Payback times are reported as 14.86 and 3.73years, respectively.