Food Industry Waste’s Exploitation via Anaerobic Digestion and Fermentative Hydrogen Production in an Up-Flow Column Reactor

Abstract

The present study focuses on the exploitation of food industry waste for hydrogen and methane production, via biological processes. Fermentative hydrogen production in an anaerobic up-flow column reactor (AUFCR), using indigenous microbial species and fed with the soluble fraction of the waste coming after an extraction procedure, was investigated at different Hydraulic Retention Times (HRTs) in the range of 12–2 h. The highest hydrogen production rate (2.94 ± 0.37 L H2/L/d) was obtained at the HRT of 2 h, while the highest yield of hydrogen produced per mol of consumed carbohydrates, expressed in glucose equivalents was achieved at the HRT of 12 h (0.14 ± 0.01 mol/mol). Methane production via anaerobic digestion (AD) in a CSTR—type reactor was also assessed, using the whole diluted food industry waste (without extraction). The HRTs tested were 20, 15 and 10 days, while when the reactor operated at the HRT of 10 days, the feeding medium was also thermally treated, in order to assess the effect of pretreatment in AD. The maximum methane production rate (0.24 ± 0.02 L CH4/L/d) was observed for the HRT of 10 days and thermally treated substrate, while the maximum methane yield was obtained at the HRT of 15 days (247.9 ± 0.15 L CH4/kg waste). The IWA ADM1 model was finally used to predict the anaerobic digesters’ behavior through the operational period, resulting to a quite satisfactory simulation for a wide range of operational conditions.