PETASE/MHETASE BIOCATALYSIS FOR PLASTIC DEGRADATION IN MUNICIPAL WASTEWATER SYSTEMS: OPPORTUNITIES, CHALLENGES, AND FUTURE PROSPECTS

Abstract

Polyethylene terephthalate (PET) plastic pollution has emerged as a significant environmental problem because it is not biodegradable and because of its harmful tendencies of accumulation in water bodies. Municipal waste water systems are also seen to be critical pathways in the distribution of microplastics, which demonstrates the necessity of novel remediation methods. The critically analyzed information presented in this review indicates that PETase and MHETase enzymatic biocatalysis have potential to be used as a sustainable method of PET degradation in wastewater infrastructure. The synergistic interaction between MHETase to convert intermediates to assailable monomers and PETase to depolymerize plastics is addressed as one of the biochemical control over recycling of plastics. Existing wastewater treatment regimens such as the preliminary, primary and secondary treatment are appraised to find constraints in microplastic removal. The review also examines bioaugmentation techniques, enzyme inhibition aspects and operational issues like hydraulic retention time and matrix related inhibitors that determine catalytic ability. Economic evaluations suggest that enzymatic crushing or recycling of PET can save on energy needs, production of greenhouse gases, and the expenses of producing petroleum-based products than the traditional PET manufacturing. Also, recent in situ remedies like engineered microbial biofilms, dual-enzyme cascade systems, and thermostable hydrolases are discussed as having the potential to enhance the stability of enzymes and catalytic efficiency in dynamic wastewater environments. Although enzyme engineering and bioprocess design have made great progress, large scale application is hampered by environmental variability and system integration issues. The present review highlights the fact that the optimization of enzyme systems, strong microbial consortia, and enhanced reactor designs are required to process laboratory-scale PET biodegradation into the applications of sustainable wastewater treatment.