Effect of temperature on kinetics of biogas production from macroalgae

An assessment was carried out on the effect of temperature on the anaerobic digestion of Laminaria digitata biomass, in batch reactors (25, 35, 45 and 55 °C) with a hydraulic retention time of 40 days. The first order, modified Gompertz and logistics models were used to obtain the kinetic parameters of the biogas production process. Results indicate the chemical composition of the algae substrate could be written as C316H613O289N13S1, with a theoretical methane yield of 336 ± 0.86 L CH4 kg VS−1. Experimental methane yield obtained from the reactors for 25, 35, 45, and 55 °C were 318 ± 1.58, 293 ± 1.11, 271 ± 0.98 and 352 ± 0.63 mL CH4/gVS respectively. Their R2 > 0.90 indicate both models fits well for predicating kinetics of methane production. The lowest kh (0.31), high biodegradability index (0.96) and lag time (9.3-11.7 days) were obtained for 55 °C.