Enzymatic Remediation of Bisphenol A from Wastewaters: Effects of Biosurfactant, Anionic, Cationic, Nonionic, and Polymeric Additives

One of the limitations compromising the utilization of enzymes for the remediation of phenolic wastewaters is enzyme activity loss during the treatment. Some surface active additives have the potential to protect enzymes and, thus, improve their performance. In this study, the removal of bisphenol A from synthetic wastewater samples by laccase has been studied in the presence of rhamnolipid biosurfactant (RL), polyethylene glycol (PEG), Triton X-100, cetyltrimethylammonium bromide (CTAB), and sodium dodecylbenzenesulfonate (SDBS). The results demonstrated that the addition of 1 ppm RL provides the highest removal rate and removal extent of BPA. In the case of PEG and Triton X-100, the results showed that both additives have almost similar positive effects on the enzymatic remediation of BPA. However, unlike RL, the positive effects of PEG and Triton X-100 were appreciable only at higher concentration (i.e., 25 ppm). On the other hand, the addition of the two ionic surfactants (SDBS and CTAB) resulted in a negative effect on the enzyme activity and, thus, the remediation of BPA, demonstrating the undesirable interactions of these ionic surfactants with laccase. The negative effect of the charged additives was more pronounced for the case of the positively charged additive (i.e., CTAB).