Rethinking microplastic cleanup: sustainable bioremediation compared to conventional physical-chemical methods

Abstract

Microplastics (MPs) (<5 mm) are hydrophobic and can't be easily degraded. These particles accumulate due to the excessive discharge of plastic waste from domestic and industrial sources, along with several toxic compounds attached to their surface, are also being deposited in environmental matrices, hampering the sustainable environment and human well-being. In the present scenario, to maintain sustainability, there is an urgent need to develop sustainable removal technologies. Physical and chemical treatment of MP removal, such as membrane filtration, density separation, adsorption, coagulation, and photo-catalysis, works effectively, but it is limited by sustainable energy demand, high cost, and secondary pollutants. Ultrafiltration membranes composed of polyether sulphone (PESP) are able to 91–96% removal efficiency for PE, PVC, while Zn–Al layered double hydroxide granules removed up to 96% of nano plastic debris (NPDs). In biological remediation, Aspergillus tubingensis degraded approximately 90% of polyurethane (PUR) through esterase and lipase activities at 37 °C under aerobic conditions within 60 days, whereas Phanerochaete chrysosporium removed up to 31% of PVC through peroxidase under acidic aerobic conditions. The primary objective of this study is to critically evaluate physical-chemical MP removal technologies, in comparison with bioremediation, which is more sustainable, cost-effective, eco-friendly process. Microorganisms and their enzymes degrade MPs by breaking them through fragmentation, de-polymerization and mineralization. MP degradation by mixed-culture, including bacteria, fungi, and microalgae, is more sustainable method to mitigate the emerging MP contamination. This review highlights the advantages of bioremediation over conventional processes, emphasizing its potential for large-scale application in MP management.