Removal of BPA by enzyme polymerization using NF membranes

The application of laccase and peroxidase from horseradish (HRP) to facilitate the removal of bisphenol A (BPA) from aqueous solutions was investigated. Effect of pH and the enzyme dose was evaluated in order to determine the optimum conditions for the enzyme performance. The results indicate that BPA was quickly removed from aqueous solution since a BPA conversion over 95% was obtained in 180 min for both enzymes in optimal conditions; the higher the enzyme dose, the higher the removal percentage of BPA. It was also found that the optimum pH for the removal efficiency of BPA was around 7 for both enzymes. The use of a membrane-reactor integrated system with recycling of enzyme for BPA degradation is also presented. These results demonstrate the potential and limitations of using enzymatic BPA degradation, operated in a recycling mode coupled to a nanofiltration membrane. BPA removal efficiencies for several NF membranes were related to the BPA molecular weight, membrane pore sizes and membrane hydrophobicity. NF270 showed the best performance in membrane-assisted enzyme treatment: 89% removal of BPA for the two enzyme treatments and less than 35% flux decay were observed.