Biochemical methane potential of oil-extracted microalgae and glycerol in co-digestion with chicken litter

Abstract

The objective of this work was to evaluate the technical feasibility of using both oil-extracted microalgae (M) and glycerol (G) in co-digestion with chicken litter (CL), thereby improving biochemical methane potential (BMP). Different feedstock ratios of M (0-30%), G (0-3%) and CL (67-100%) were investigated to determine the best co-digestion condition under mesophilic conditions. According to the modified Gompertz model, the best BMP (131.1mLCH₄g_VSfed^-1) was obtained with the triple co-digestion (M:G:CL) in a proportion of 30:3:67. This yielded a methane production rate (μ_m) of 3.3mLCH₄g_VSfed^-1d^-1 and a lag time (λ) of 17.4d. This treatment reduced chemical oxygen demand (COD) by 91.02% and increased the methane yield 15.8% with respect to the CL control.

Keywords: Biodiesel residuals; Glycerol; Gompertz model; Mesophilic; Oil-extracted microalgae; VFAs profile.