Efficient removal of pollutants from olive washing wastewater in bubble-column bioreactor by Trametes versicolor

The white-rot fungi Panus tigrinus, Funalia trogii and Trametes versicolor have been tested in shake flasks for the reduction of olive washing wastewater (OWW) pollutants and production of oxidases on OWW-based media. P. tigrinus was rejected for its scarce performance. F. trogii showed best production of laccase (27 000 U g⁻¹), while T. versicolor appeared a good pollutant degrader reducing colour, COD and phenols by 60, 72 and 87%, respectively. Only T. versicolor grew well in bubble-column bioreactor: its OWW depollution, in continuous process, led to colour, COD and phenols reduction by 65%, 73% and 89%, respectively. Optimal dilution rate was 0.225 d⁻¹ (0.225 m³ of effluent treated daily per m³ of bioreactor). Thus, a small bioreactor (10 m³) could treat daily the amount of OWW produced by a standard olive washing machine (2 m³ d⁻¹). For these reasons, this process could be proposed as a simple, efficient and low-cost OWW treatment.