Effectiveness assessment of olive mill wastewater treatment by combined process: Natural flotation and anaerobic‐aerobic biodegradation

Abstract

Abstract The present work intends to study the treatment of olive oil mill wastewater (OMW) by natural flotation followed by anaerobic‐aerobic biodegradation, without dilution. After natural flotation, turbidity, chemical oxygen demand (COD) and polyphenol decreased by 37.7%, 3.7% and 3.3%, respectively. Whereas, anaerobic treatment removed 23.9% of nitrate, 29.1% of turbidity and 16.2% of polyphenol. However, intermittent aeration treatment showed the reduction of nitrate, turbidity and ammonium by 90%, 26.5% and 65.1%, respectively. In general, the combined natural flotation and anaerobic‐aerobic treatment of OMW, without dilution, have led to reduced turbidity, COD, polyphenol, nitrate, ammonium and phosphorus by 67.5%, 29.1%, 25.2%, 93.9%, 77.1% and 81.8%, respectively. The germination index of the treated OMW was 69% after 30% of dilution. Finally, the proposed treatment process could be used in small and medium‐sized industries as a simple, economical and effective method. Also, the produced water could be reused for irrigation.