Treatment of wastewaters from the olive mill industry by sonication

BACKGROUND: In this study, the effects of additives (manganese (III) oxide (Mn 3 O 4 ), Cu +2 , Fe 0 and potassium iodate (KIO 3 )) and radical scavengers (sodium carbonate (Na 2 CO 3 ), perfluorohexane (C 6 F 14 ) and t‐buthyl alcohol (C 4 H 10 O)) on the dephenolization, decolorization, dearomatization and detoxification of olive mill wastewater (OMW) by sonication were investigated because wastewaters from this industry are not removed effectively. RESULTS: The maximum COD, color, total phenol and total aromatic amines (TAAs) removal efficiencies were 63, 82, 78 and 71%, respectively, at 60 °C with sonication only. The TAAs and phenol yields were increased to 96 and 97% with 6 mg L −1 KIO 3 and 3 mg L −1 Fe 0 while color removal reached 97% with 6 mg L −1 C 6 F 14. The total annual cost with sonication only was 665 € m −3 year −1 while the cost slightly increased (666€ m 3 year −1 ) with C 6 F 14 . The maximum acute toxicity removals were 97‐98% in Daphnia magna and Vibrio fischeri The Microtox acute toxicity test was more sensitive than the Daphnia magna to the OMW samples. CONCLUSION: COD, color, total phenol, TAAs and toxicity in an OMW were removed efficiently and cost‐effectively by sonication.