The bioremediation was employed to treat perchlorate-contaminated water. All enrichments and growth of mixed cultures were performed in anaerobic acetate medium. Enrichment cultures were started with activated sludge obtained from a local wastewater treatment plant where it predominantly treats domestic wastewater. Several parameters affecting perchlorate removal were examined through batch experiments, these include the amount of domesticated sludge, the acetate concentration, pH, the C/N ratio and the reaction temperature. The results indicated that acetate was an effective carbon source and electron donor. Under the selected conditions, namely 1.0 g domesticated sludge, an acetate concentration of 1.2 g l(-1), pH 8.0, a C/N ratio of 20 at 40 degrees C, 50 mg l(-1) perchlorate could be rapidly reduced to non-detectable levels within 24 h.