In this study, we successfully developed activated sludge (AS) adapted to a very high concentration (3 g/L) of phenol. A careful stepwiseadaptation process was considered important in the development of this AS. In addition, we found that processed lignite (PL) accelerated the removal of phenol which might lead to change in the dominant members of the microbial community. Phenol is an abundant industrial toxic contaminant in wastewater treatment processes.