Olive mill wastewaters treatment and valorisation in biofilm reactors packed with granular activated carbon or silica beads

Although anaerobic digestion is one of the most promising technologies for disposing olive mill wastewaters (OMWs), OMW toxic phenols tend to persist in conventional dispersed growth bioreactor effluents. The possibility of achieving a satisfactory OMW decontamination in biofilm packed bed reactors was here investigated. An OMW-digesting microbial consortium was passively immobilized in column reactors packed with granular activated carbon or “Manville” silica beads. Under batch conditions, both biofilm reactors exhibited OMW COD and phenolic compound removal efficiencies markedly higher than those attained in an anaerobic dispersed growth bioreactor developed with the same inoculum and OMW. Under continuous conditions GAC-reactor showed COD and phenolic compound depletion efficiencies along with a tolerance to high and variable organic loads largely higher than those averagely displayed by most of the conventional and packed-bed laboratory-scale reactors previously proposed for the OMW digestion.