Phenolic compounds, chemical oxygen demand and total carbon organic removal from olive mill wastewater by activated persulfate oxidation using full factorial design

Abstract This study investigated phenolic compounds (PC), chemical oxygen demand (COD) and total carbon organic total (TOC) removal from olive mill wastewater OMW via activated persulfate oxidation. Persulfate (PS, <m:math xmlns:m="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <m:mrow> <m:msub> <m:mi mathvariant="normal">S</m:mi> <m:mn>2</m:mn> </m:msub> <m:msubsup> <m:mi mathvariant="normal">O</m:mi> <m:mn>8</m:mn> <m:mrow> <m:mn>2</m:mn> <m:mo>−</m:mo> </m:mrow> </m:msubsup> </m:mrow> </m:math> ${\mathrm{S}}_{2}{\mathrm{O}}_{8}^{2-}$ ) was activated by thermal and transition metal to form sulfate radical ( <m:math xmlns:m="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <m:mrow> <m:mi mathvariant="normal">S</m:mi> <m:msubsup> <m:mi mathvariant="normal">O</m:mi> <m:mn>4</m:mn> <m:mrow> <m:mo>·</m:mo> <m:mo>−</m:mo> </m:mrow> </m:msubsup> </m:mrow> </m:math> $\mathrm{S}{\mathrm{O}}_{4}^{{\cdot}-}$ ). A mathematical model was developed, and the process variables, namely oxidant dose (0.05 and 0.1 g L −1 ), type of catalyst (Fe 2+ , Cu 2+ ), time of treatment (5 and 20 min) and temperature (25 and 45 °C) and their interaction were examined using a full factorial design methodology 2 4 . The results indicated that activation methods are efficient for reduction of PC and COD in OMW. Under conditions maximizing responses, there was a considerable increase in PC, COD and TOC removal (44.73 %, 62.39 % and 95.13 % respectively). The correlation coefficient values of the polynomial model were found to be 90 % (CP removal) and 86 % (COD removal). The predicted values obtained using the response functions agreed well with the experimental data.