Optimization of high phenol-containing wastewater treatment by Fenton oxidation method using response surface methodology

Some industrial wastewaters contain high contents of phenolic compounds, so that the removal of these compounds is not possible through biological treatment. Fenton process is known to be a suitable alternative because of the ease of construction and operation in different scales and economic considerations. The aim of this study was to investigate the effects of the independent variables of operation in total phenol oxidation by Fenton process and their optimization.

This experimental study was conducted on a laboratory scale in a 1.5 liter Plexiglas reactor. Wastewater samples were taken from an olive oil mill plant. Independent variables of process included H2O2 / Fe2 + ratio, pH and reaction time, each of them was studied at five levels. Experiments were designed by central composite design using Design Expert 7.0 software. Ethical considerations were observed at all stages of the study.

The results revealed that the main, interaction and quadratic effects of all three independent variables including pH, reaction time and H2O2 / Fe2 + ratio were effective in removing total phenolic compounds. The highest effect was related to the quadratic effect of H2O2 / Fe2 + ratio and the lowest effect was associated with the quadratic effect of pH. Under optimal conditions of H2O2 / Fe2 + ratio 8, pH 2.8 and reaction time of 67 minutes, the removal efficiency of phenolic compounds reached up to 70.4%.

The results revealed that the main, interaction and quadratic effects of all three independent variables including pH, reaction time and H2O2 / Fe2 + ratio were effective in removing total phenolic compounds. The highest effect was related to the quadratic effect of H2O2 / Fe2 + ratio and the lowest effect was associated with the quadratic effect of pH. Under optimal conditions of H2O2 / Fe2 + ratio 8, pH 2.8 and reaction time of 67 minutes, the removal efficiency of phenolic compounds reached up to 70.4%.