Abstract:The activated sludge with high efficiency for the removal of benzene, toluene, and o-xylene (BTX) was inoculated on a specific carrier and enriched via a fermentation process. The composite microorganism agent applied for BTX degradation was then successfully prepared. In the microorganism agent, the active organisms was more than 109 CFU/g, and water content was less than 5%. The microorganism agent, instead of the acclimated activated sludge, could be employed for the start-up of the reactor to purify BTX without substantial loss of removal capacity. The effect of several operating parameters, including pH, drying temperature and the carrier proportion, on the performance of microorganism agent was investigated in detail. With an initial pH of 9.0, drying temperature of 35℃, and the carrier proportion of 85%: 10%: 5%, the best microorganism agent were obtained. Compared with the activated sludge, the microorganism agent had higher stability when it was stored for three months or more at 4℃.