Removals of some hydrophobic poly aromatic hydrocarbons (PAHs) and Daphnia magna acute toxicity in a petrochemical industry wastewater with ultrasound in Izmir-Turkey

The effects of increasing sonication time (60-150 min), NaCl (1.5-18 g/L), CCl4 (200-1000 mg/L), pH (2-10) and air as dissolved oxygen (DO = 2-12 mg/L) concentrations on the destruction of four polycyclic aromatic hydrocarbons (PAHs) in a real petrochemical industry wastewater in Izmir (Turkey) were investigated. The yields in more hydrophobic PAHs with high benzene rings [benzo[a]pyrene (BaP) and benzo[k]fluoranthene (BkF)] were as high as the less hydrophobic PAHs with lower benzene rings [acenaphthylene (ACL) and carbazole (CRB)] at 60 C after 150 min sonication. The removals in all PAHs increased significantly as the NaCl concentrations were increased from 1.5 up to 8g/L, respectively. Continuous sparging of 5 mg/L DO increased the yields to 98% in less hydrophobic PAHs while more hydrophobic ones are removed with low yields. The more hydrophobic BaP, BkF and less hydrophobic ACL and CRB PAHs were sono-degraded under acidic and alkaline conditions, respectively, with high yields. The sono-destruction efficiency of more hydrophobic PAHs (97%) was enhanced by 17% with 600 mg/L CCl4 after 150 min of sonication while the yields of less hydrophobic PAHs remained around 82%. Sonication alone provided 80% PAH yields. OH center dot was the main process for complete sono-degradation of the ACL and CRB PAHs while pyrolysis was the main process for complete degradation of BaP and BkF PAHs. The Daphnia magna acute toxicity was significantly reduced. (C) 2011 Elsevier B.V. All rights reserved.