Start-Up Study on Biohydrogen from Palm Oil Mill Effluent in a Pilot-Scale Reactor

A start-up study for biohydrogen production from palm oil mill effluent (POME) is carried out in a pilot-scale up-flow anaerobic sludge blanket fixed-film reactor (UASFF). A substrate with a chemical oxygen demand (COD) of 30 g L(-1)is used, starting with molasses solution for 30 days and followed by a 10% v/v increment of POME/molasses ratio. At 100% POME, a hydrogen content of 80%, hydrogen production rate of 36 L H(2)per day, and maximum COD removal of 48.7% are achieved. Bio-kinetic coefficients of Monod, first-order, Grau second-order, and Stover-Kincannon kinetic models are calculated to describe the performance of the system. The steady-state data with 100% POME shows that Monod and Stover-Kincannon models with bio-kinetic coefficients of half-velocity constant (K-s) of 6000 mg COD L-1, microbial decay rate (K-d) of 0.0015 per day, growth yield constant (Y) of 0.786 mg volatile suspended solids (VSS)/mg COD, specific biomass growth rate (mu(max)) of 0.568 per day, and substrate consumption rate of (U-max) 3.98 g/L day could be considered as superior models with correlation coefficients (R-2) of 0.918 and 0.989, respectively, compared to first-order and Grau's second-order models with coefficients ofK(1)1.08 per day,R(2)0.739, andK(2s)1.69 per day,a= 7.0 per day,b= 0.847.