Hydrogen production by co-digesting cheese whey and glycerin in an AnSBBR: Temperature effect

Anaerobic processes are strongly influenced by temperature and there is considerable disagreement about the ideal or even an ideal range of temperature for biological hydrogen production. Hence, this paper was designed to study the temperature effect in the mesophilic range (20, 25, 30 and 35 °C) on biohydrogen production in AnSBBR (anaerobic sequencing batch biofilm reactor) that co-digested dairy industry effluent (cheese whey) and biodiesel production effluent (glycerin). Influence of the inoculum heat shock pretreatment and micronutrients solution added to influent were also assessed. The best condition for hydrogen production was at the temperature of 30 °C, in which it was achieved a productivity of 129.0 molH2. m−3.d-1 and a yield of 5.4 molH2.kgCOD-1. Both micronutrient solution and inoculum pretreatment were proven necessary for a better hydrogen productivity. Productivity increased until 30 °C, but at 35 °C the exacerbated amount of biomass produced caused a rapid decrease in hydrogen production. From the kinetic model, it was observed that the majority of hydrogen production comes from the acidogenesis phase (k1H = 1.4 h-1, k3H = 1.4 h-1, k4H = 1.4 h-1). The calculated kinetic constants were used to estimate the activation energy of each reaction of the acidogenesis phase by using the Arrhenius model: 110-220 kJ.mol-1.