Removal of phenolic compounds from synthetic wastewater using soybean peroxidase

Experiments were conducted to investigate the efficiency of using soybean peroxidase (SBP) to remove several different phenolic compounds from unbuffered synthetic wastewater. The phenol derivatives studied included parent phenol, chlorinated phenols, cresols, 2,4-dichlorophenol and 4,4′-isopropylidenediphenol (commonly known as bisphenol A). Optimum conditions to achieve at least 95% removal of these compounds were determined for the following parameters: pH, SBP dose in the absence and presence of polyethylene glycol (PEG), hydrogen peroxide to substrate ratio, and PEG dose. Experimental results showed that SBP efficiently removed aromatic compounds from synthetic wastewater in the presence of hydrogen peroxide. An increase in the hydrogen peroxide to substrate ratio beyond the optimum resulted in enzyme inactivation in all cases except for bisphenol A. The optimum pH for different phenolic compounds ranged from 5.5 to 8. For each substrate, the optimum enzyme dose in the presence of PEG varied significantly. The studies showed that PEG only slightly reduced the amount of SBP required for 95% removal of the substrate. For most of the substrates, an increase in PEG dose beyond the optimum dose did not significantly change the removal efficiency.