Co-metabolism of olive mill wastewater in sequencing batch reactor under aerobic conditions after Fenton-based oxidation

The study explored the experimental conditions to enable co-metabolism of olive mill wastewater, (OMW), pretreated by Fenton-based oxidation, when combined with a compatible waste in a sequencing batch reactor (SBR). For this purpose, peptone mixture was used as the synthetic substrate, well tested for its similar biodegradation character with sewage. Emphasis was placed upon the degree of dilution that could be afforded without upsetting the performance of biological process. The SBR operation involved four cycles a day, at a sludge age of 8.0 days. The COD level of the peptone mixture feeding was kept constant as 400 mg/L, to simulate a relatively weak sewage. After acclimation of biomass to the synthetic substrate, SBR operation continued for 105 days with gradually increasing OMW additions in four consecutive phases with COD increments between 40 and 100 mg/L and no OMW addition in the last phase. Co-metabolism with complete removal of biodegradable COD in OMW could be sustained under cyclic steady-state conditions of each phase. Biodegradation characteristics of OMW could be defined in terms of COD fractionation and process kinetics; they were used in model simulation of in-cycle COD profiles at the end of each cycle. The study advocated co-metabolism as a novel and sustainable approach of wastewater management of olive mill wastewater, when properly diluted in sewage or a compatible wastewater and jointly subjected to biological treatment, a pre-requisite for OMW. It is believed that the proposed approach embodies all scientific and practical attributes to provide the long-awaited solution for this industry.