Continuous hydrogen and methane production in a two-stage cheese whey fermentation system

摘要

The feasibility of integrating biological hydrogen and methane production in a two-stage processnusing mixed cultures and cheese whey powder (CWP) as substrate was studied. The effect ofnoperational parameters such as hydraulic retention time (HRT) and organic loading rate (OLR) on thenvolumetric hydrogen (VHPR) and methane (VMPR) production rates was assessed. The highest VHPRnwas 28 L H2/L/d, obtained during stable operation in a CSTR at HRT and OLR of 6 h and 142 g lactosenL/d, respectively. Moreover, hydrogen (13 L/L/d) was produced even at HRT as low as 3.5 h and OLRnof 163 g lactose/L/d, nonetheless, the reactor operation was not stable. Regarding methanenproduction in an UASB reactor, the acidified effluent from the hydrogen-producing bioreactor wasnefficiently treated obtaining COD removals above 90% at OLR and HRT of 20 g COD/L/d and 6 h,nrespectively. The two-stage process for continuous production of hydrogen and methane recoverednover 70% of the energy present in the substrate. This study demonstrated that hydrogen productionncan be efficiently coupled to methane production in a two-stage system and that CWP is an adequatensubstrate for energy production.