Treatment of cutting oil wastewater by coagulation and sono-fenton processes

Abstract

To investigate the applicability of acoustic oxidation, which is an advance oxidation processes (AOPs), on the treatment of cutting oil wastewater that could not be easily treated by conventional processes. The effect of physical parameters which are ultrasonic intensity, temperature, and oil concentration, were determined as well as the enhancement effects caused by the addition of other conventional oxidant as hydrogen peroxide, aeration, and Fenton’s reagents. However, the results showed that acoustic oxidation alone is not effective in eliminating COD from the sample, and Fenton reagents should be added in order to enhance the performance. It is also found the process, known as sono-Fenton, could reduce the COD up to 92.3 percent using 140 g/L hydrogen peroxide and 500 mg/l Fe2+. The amount of required chemical is considerably high but could be optimized using reaction kinetic parameters determined. Additionally, this study investigated the possibility of incorporating advance oxidation processes as the post-treatment of conventional coagulation-flocculation process, which serves two purposes: (1) minimizing constituents in the effluent and (2) reducing chemical usage. In this study, COD of the wastewater was found to be able to reduce from over 2,000 mg/l to the level that is undetectable by the analysis method used in this study. The amount of chemical used is minimal, and the processes could be compared and practically designed on theoretical background.