A moderate halophilic organism was isolated from the Great Salt Lake, UT, USA which utilized phenol in a simulated waste brine containing 1–15% salt. Growth characteristics of this organism were not affected by preculture salt concentration. When placed in a periodically operated Sequencing Batch Biofilm Reactor (SBBR), the organism formed a biofilm on the gas permeable silicone tubing used to aerate the reactor. Reactor performance was not effected by large (14%) step changes in salt concentration. The results suggest that biofilms of halophilic bacteria can be used to effectively treat waste brines with high and variable salt contents.