Initial pH influences in-batch hydrogen production from scotta permeate

We studied the influence of initial pH on hydrogen (H2) production using permeate from scotta (a partially deproteinized cheese whey from ricotta production) as substrate (51 g L−1lactose). Dark fermentation was carried out at 35 °C in laboratory batch reactors, in an unbuffered system. Hydrogen production and metabolite (volatile fatty acids, ethanol, and lactic acid) evolution during a 96-h period were monitored in reactors with initial pH varying in the range 4–10. In all reactors, H2production started only when pH fell below 6. However, it was much higher (+31%) in the reactors with initial alkaline pH. We conclude that H2production occurs only at acidic pH values, but initial alkaline pH values increase the overall H2production in dark fermentation of lactose-rich substrates.