FIG. 2.

Metabolic properties of the EGSB aggregates. (A and B) Methane production rates (lines) from a mixture of acetate (▵), propionate (○), and butyrate (▪) by granular sludge (A) and crushed granular sludge (B). ×, hydrogen. (C) Methane production rate of crushed aggregates. The first substrate feed (F1) consisted of ∼1,000 mg of acetate COD/liter, and the second substrate feed (F2) consisted of ∼1,500 mg of ethanol COD/liter added to one batch reactor (solid line) and ∼1,500 mg of acetate COD/liter added to a second batch reactor (dashed line). (D) Methane production rates from ethanol by intact (dashed line) and crushed (solid line) aggregates. Arrow (C and D), tailing on the methane production rate curve from the crushed biomass due to acetotrophic methanogenesis.