Maximizing H₂ yields in continuous flow bioreactors

An experimental matrix consisting of two factors, HRT (10, 5, 2.5, and 1 hr) and glucose concentration (10, 7.5, 5, and 2.5 g-COD/L), was conducted to understand the degree of H₂ partial pressure inhibition on H₂ production. Heat shocked (100°C, 2 hr) agricultural soil was used as the inoculum. As the HRT increased from 1 to 10 hr and the glucose concentration decreased from 10 to 2.5 g/K, H₂ yields increased from 43 to 77% or 1.7 or 3.1 moles of H₂ per mole glucose. H₂ production rates at the lowest HRT (1 hr) depended on the ability of the culture to flocculate. Glucose removal increased as the HRT decreased due to the importance of flocculation and maintenance of high biomass concentrations. This is an abstract of a paper presented at the 228th ACS National Meeting (Philadelphia, PA 8/22-26/2004).