Effects of sludge retention time (SRT) and biosurfactant on the removal of polyaromatic compounds and toxicity

► Over 90% of the total PAHs was removed at Rhamnolipid and sludge retention time of 15 mg l−1 and 25 days. ► 93% of the COD originating from the inert organics was removed in the aerobic reactor. 96-97% of the Rhamnolipid was biodegraded. ► The EC50 value was reduced from EC50 = 45.02 ng ml−1 to C6 = 5.30 ng ml−1 with Daphnia magna. Toxicity removals originating from the PAHs were 96%.