Removal of Phenolic Compounds from Olive Oil Mill Wastewater using Ralstonia eutropha in an Airlift Bioreactor with Internal Net Draft Tube

Aromatic compounds such as total phenolic (TP) compounds commonly present in effluents of food and agricultural industries such as Olive mill wastewater (OMW). The high concentration of TP in OMW is usually associated with high measurement of chemical oxygen demand (COD). Discharge of these chemicals to water ways can creat hazardous environmental condition and have adverse impact of the living organisms. Biological treatment is the most effective method for removing or partially decreasing these chemicals from wastewater. In this study, the biodegradation of OMW was investigated by using an airlift bioreactor with Ralstonia eutropha equipped with net draft tube (ALR-NDT). The effect of aeration rate and initial TP concentration on the efficiency of the biodegradation process was studied. Innitially, the effect of three aeration rates (100, 200, and 400 mL/min) on TP reduction was studied. The aeration rate of 200 mL/min was found to be as the optimal aeration rate for the biodegradation process. Following these initial experiments, the effect of the three initial OMW concentrations (660, 1220, and 2620 mg/L) were evaluated on TP reduction in the follow up experiments. Results of our study showed that the TP reduction under the above three initial OMW concentrations were 95%, 96%, and 58%, respectively. The maximum TP reduction (96%) were accomplished when the initial TP concentration was1220 mg/L. For future kinetic modeling investigation, we were able to use the experimental data and confimed the behavior of the process as a Monod kinetic model with kinetic coefficients of µmax= 0.22 1/hr and Ks= 863 mg/L. According to the our preliminary results, Ralstonia eutropha was found to be capable of degrading high concentration of phenolic compounds from industrial wastewater.