Removals of PAHs and acute toxicity via sonication in a petrochemical industry wastewater

The effects of ambient conditions (25 C), increasing sonication time (0-150 min), temperature (30-60 degrees C), dissolved oxygen (DO, 2-10 mg L(-1)) and hydrogen peroxide (H(2)O(2), 100-2000 mg L(-1)) concentrations on the removal of polycyclic aromatic hydrocarbon (PAH) and destruction of toxicity in a petrochemical industry wastewater in Izmir (Turkey) were investigated. The maximum PAH removals were 80.2%, 91%, 98.5% and 98% at 25 degrees C, 60 degrees C, DO concentration of 6 mg L(-1) and H(2)O(2) concentration of 2000 mg L(-1), respectively, after 150 min sonication. Sonication alone provides PAH removals varying between 88% and 92% without DO and H(2)O(2) at 30 degrees C and 60 degrees C after 150 min sonication. The Daphnia magna acute toxicity decreased significantly from 342.6 ng mL(-1) to 5.4 ng mL(-1), to 0.7 ng mL(-1), and to 0.4 ng mL(-1), respectively, as the temperature, the DO and the H(2)O(2) concentrations were increased. The PAH sonodegradation appeared to be pseudo first order in PAHs naphthalene (NAP), acenaphthylene (ACL), phenanthrene (PHE), pyrene (PY) and benz[ 131 fluoranthene (BbF) (k = 0.026 min(-1). 0.024 min(-1), 0.017 min(-1), 0.015 min(-1) and 0.011 min(-1), respectively). The main mechanism of PAH sonodegradation appears to be pyrolysis. (C) 2010 Elsevier B.V. All rights reserved