Monitoring the biochemical hydrogen and methane potential of the two-stage dark-fermentative process.

A two-step process has been recently proposed whereby the products of biological hydrogen production processes are used as substrates for biological methane production. The aim of the present study is to evaluate a simple bench-scale batch procedure for measuring the biochemical hydrogen and methane potential of organic substances as a two-step simulated process. Glucose fermentation showed an hydrogen and methane recovery (measured as the ratio of electron equivalents recovered as hydrogen and methane and electron equivalents of the initial substrate added) from the initial substrate of 13.3% and 75.5%, respectively, that approximates mass balance closure. On the contrary, gas recoveries ranging from 61% to 75% were measured from wastes originating from the food-industry. Moreover, the results demonstrate that the substrate origins significantly influence the ratio of H(2) and CH(4) recovery.