Abstract: Drilling wastewater contains various organic additives and oil contaminants produced by the process of oil -gas exploration and development operation. By the technique of aerobic biologi cal treatment，we use the activated sludge taken from the munic-ipal sewage plant to disposal drilling wastewater, and investigate the biodegradation feasibility by determination the curves of bio-
logical respiration rate. Some factors such as microorganism nutrition, Mixed Liquor Suspended Solid(MLSS) and acclimation of activated sludge have been studied to analysis the influence of biodegradation. Results show that biodegradation is feasible for drilling wastewater, and the acclimatized activated sludge has more efficiency.

Key words: drilling wastewater, activated sludge, aerobic biological oxidation, biochemical respiration, biodegradation feasibility