The effect of trace organics on the inhibition of gas production by anaerobic sludges: Batch studies

Gallic acid was used as a model inhibitor in a series of batch trials examining the anaerobic digestion of a substrate based on starch (1 g/l). Simple organic compounds were also added in trace (5 mg/l) quantities. The inhibition of digestion efficiency was assessed in terms of biogas production and gas composition. Some of the trace organics, specifically glucose and glycine, behaved antagonistically to the inhibitory effects of the gallic acid. The effect was quantified in terms of an activity term, based on the methane volumes produced. For glucose, its value was 56% and for glycine it was 38%. Altering the amounts of glucose did change the extent of the antagonism. In practical terms, the most effective concentration would be between 8 and 10 mg/l.