Removal of phenolic compounds from synthetic wastewater using soybean peroxidase.

Soybean peroxidase (SBP), an acidic peroxidase which is isolated from the hulls of the bean, catalyzes the oxidation of various aqueous aromatic compounds in the presence of hydrogen peroxide. The polymers formed during the reaction have a lower solubility than their monomeric precursors, and are readily precipitated from solution. Experiments were conducted to investigate the efficiency of using SBP to remove several different phenolic compounds from unbuffered synthetic wastewater All tests were carried out in continuously stirred batch reactors. The phenol derivatives studied included parent phenol, chlorinated phenols and methyl phenols. The optimum conditions to achieve at least 95% removal of the phenolic 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 wastewater in the presence of hydrogen peroxide. An increase in the hydrogen peroxide to substrate ratio beyond the optimum resulted in enzyme inactivation, which reduced the substrate removal efficiency. The optimum pH for different phenolic compounds ranged from 5.5 to 8. For each substrate, the optimum enzyme dose varied significantly with the lowest being 0.015 U/mL for bisphenol A and with the highest being 0.60 U/mL for phenol. The studies showed that PEG reduced the amount of SBP required for 95% removal of the substrate by up to 60 times, as was the case for bisphenol A. For all substrates, except p-cresol, an increase in PEG dose beyond the optimum did not significantly increase or decrease the removal efficiency.Dept. of Civil and Environmental Engineering. Paper copy at Leddy Library: Theses & Major Papers - Basement, West Bldg. / Call Number: Thesis1998 .C39. Source: Masters Abstracts International, Volume: 39-02, page: 0571. Adviser: J. K. Bewtra. Thesis (M.A.Sc.)--University of Windsor (Canada), 1998