However ERY and ST at 400 mg L1 caused a 74.5% and 57.6% inhibition to specific sulfidogenic activity (SSA) when the sludge granules were disrupted and ethanol used as substrate. After disruption, microbial tolerance to antimicrobials decreased, but the rate at which MPA utilized acetate and ethanol increased from 0.95 gCOD(gVSSd)1 to 1.45 gCOD(gVSSd)1 and 0.90 gCOD(gVSSd)1 to 1.15 gCOD(gVSSd)1 respectively. The ethanol utilization rate for SRB also increased after disruption from 0.35 gCOD(gVSSd)1 to 0.46 gCOD(gVSSd)1.