Effet of fenton based oxidation processes on the biological treatability of olive mill wastewaters

Olive mill wastewaters contain high concentrations of organic matter and phenolic compounds. Fenton based oxidation processes are one of the processes applied for phenol removal. However, high chemical costs limit the application of fenton-based processes alone. The application of the fenton process as a pre-treatment process prior to biological treatment for partial oxidation of wastewater to convert toxic compounds into less harmful compounds can be applied as a suitable process combination. Accordingly, the aim of this thesis is to investigate the applicability of fenton based oxidation processes as a pre-treatment process in order to increase the treatability of olive mill wastewaters by aerobic biological process. For this purpose, optimum operating conditions were determined for efficiently treatment of olive mill wastewaters by fenton process and fenton-like process including trivalent iron use as catalyst. 20% COD and 80% phenol removal efficiencies were obtained by applying fenton process in the optimum operating conditions, while 26% COD and 81% phenol removal efficiencies were achieved by applying fenton-like process. Implementation of the fenton-like process with the assistance of ultrasound enabled similar COD and phenol removal efficiencies to be achieved with less chemical consumption. In order to determine the effects of fenton based processes on reducing the toxic effects of olive mill wastewaters, inhibition tests were performed. The inhibition effects of olive mill wastewaters were reduced 59% by applying fenton process, while the implementation of fenton-based process resulted with the 67% reduction in the inhibition. According to result of this study, it is concluded that the fenton-like process is more efficient than the fenton process for the treatment of olive mill wastewaters.