Strategies for the design and operation of enzymatic reactors for the degradation of highly and poorly soluble recalcitrant compounds

Abstract

The presence of recalcitrant compounds in both wastewaters and soils is an important environmental problem. Oxidative enzymes from white-rot fungi have been successfully utilised for the in vitro degradation of xenobiotics, such as the azo dye Orange II and the polycyclic aromatic hydrocarbon anthracene (compounds with high and low solubilities, respectively). Two different reactor configurations are proposed: (i) an enzymatic membrane reactor for the treatment of soluble compounds, consisting of a continuous stirred tank reactor coupled to an ultrafiltration membrane to facilitate the retention and recycling of enzyme; and (ii) a two-phase enzymatic reactor for the degradation of poorly soluble compounds, consisting of an immiscible solvent, which contains the contaminant at high concentrations, and the aqueous phase containing the enzyme and cofactors involved in the catalytic cycle. In this paper, factors affecting the design and operation of both systems are discussed, and experimental results concerning the efficiency and stability of the processes are presented.