Enzyme catalyzed polymerization and removal of bisphenol A from wastewater with laccase

Enzymatic treatment of synthetic wastewater containing bisphenol A (BPA) was investigated in the presence and absence of polyethylene glycol (PEG). The study was carried out in three distinct phases.; In the first phase, enzymatic treatment of the wastewater was optimized by using laboratory batch reactors. Effluent BPA reduction of >95% was considered as a target for optimization of laccase and PEG concentrations. The optimum pH for bisphenol A (BPA) removal using laccase both in the absence and presence of PEG was 5.6+/-0.1, Adding of PEG reduced the enzyme inactivation and allowed a 5.2-fold reduction in the quantity of laccase required. The stoichiometric ratio of BPA and oxygen was approximately 2.; In the post-treatment phase, adding alum to the batch reactors increased in clear liquid volume in a settling column both in the presence and absence of PEG. An undesired result of this treatment process was a decrease in pH, which was attributed to the presence of alum. Addition of lime to the batch reactors, both in the absence and presence of the PEG, did raise the pH of the treated waste to approximately 6.0.; Kinetic studies yielded the values of apparent Michaelis constants for BPA and oxygen, in the presence and absence of PEG. A kinetic model was developed for batch reactions under various laccase, BPA and oxygen concentrations. The correlation between the theoretical and experimental results was good indicating that the model employed was suitable for describing the reaction kinetics. Further development is required to define the mechanisms and kinetics of inactivation, to extend the application of the model to the design of a full-scale waste treatment system.; The objective of any waste treatment should be to reduce its impact on the environment. Since the enzymatic reaction involves the formation of polyaromatic by-products that are not soluble, to define the impact of these by products the first step is to identify them. These insoluble products were characterized by HPLC-MS and the computational software CACHE. More thorough investigation is required to define the mechanism of such product formation.