A kinetic study of biohydrogen production from glucose, molasses and cheese whey by suspended and attached cells of Thermotoga neapolitana.

Batch tests of H2 production from glucose, molasses and cheese whey by suspended and immobilized cells of Thermotoga neapolitana were conducted to develop a kinetic model of the process. H2 production was inhibited by neither H2 (up to 0.7 mg L(-1)) nor O2 (up to 0.2 mg L(-1)). The H2 specific rates obtained at different substrate concentrations were successfully interpolated with Andrew's inhibition model. With glucose and molasses, biofilms performed better than suspended cells. The suspended-cell process was successfully scaled-up to a 19-L bioreactor. Assays co-fed with molasses and cheese whey led to higher H2 productivities and H2/substrate yields than the single-substrate tests. The simulation of the suspended-cell continuous-flow process indicated the potential attainment of H2 productivities higher than those of the batch tests (up to 3.6 mmol H2 h(-1) L(-1) for molasses and 0.67 mmol H2 h(-1) L(-1) for cheese whey) and allowed the identification of the optimal dilution rate.