A comprehensive review of microbial exopolysaccharide for bioremediation of environmental pollutants and industrial waste toxicants using sustainable strategies: bottlenecks and future perspectives

Abstract

Microbial exopolysaccharides (EPS) offer efficient and sustainable approaches to remediate environmental pollutants. Its distinctive structural features, abundant in functional groups including carboxyl, hydroxyl, phosphate, sulfate, and amino groups, facilitate robust interactions with heavy metals, petrochemical residues, industrial dyes, and many hazardous pollutants. EPS promotes the removal of pollutants through various physico-chemical interactive mechanisms, such as chelation/complexation, biosorption, ion exchange, bioflocculation, and emulsification. EPS may demonstrate pollutant-binding and detoxification potential of contaminants such as Pb²⁺, Cd²⁺, Cr⁶⁺, polycyclic aromatic hydrocarbons (PAHs), crude oil hydrocarbons, and synthetic colors under laboratory conditions, though efficiency varies with environmental parameters and pollutant complexity. However, no commercialized bio-product is available that employs green, sustainable strategies to eliminate health-hazardous pollutants. The regulatory consequences of EPS-based product development are under-researched. A comprehensive review of sustainable green strategies for EPS-based bioreactors to treat environmental pollutants, heavy metals, and industrial waste/dye effluents in wastewater is discussed. Study highlights limitations and deficiencies in bioremediation using reinforcement strategies. It explores future research directions for the practical implementation of EPS-based nanotechnology, photocatalytic skills, carbon nanodot matrices, and biochar sludges to enhance sorption capacity and provide workable solutions for a satisfactory bioremediation process, though challenges remain in recovery, stability, and large-scale application. It evaluates cost-effective, high-performance EPS bio-material designs, while noting that scalability and regulatory approval remain critical challenges to deployment. It assesses the functional properties, pollutant-interaction mechanisms, and bioremediation efficiency of EPS, demonstrating their potential as environmentally safe, biodegradable, renewable, and biocompatible biomaterials for scientists seeking to develop efficient methods to treat extreme industrial wastewater and reclaim valuable resources. The review elucidates how EPS-based biodevices showcase promise for pollutant removal, addresses bottlenecks to progress, and outlines future directions, where industrial deployment is limited by production costs, yield variability, and regulatory gaps. The study illustrates the potential interactions between environmental pollutants and EPS, using physicochemical properties to disseminate bioremediation. EPS-based emerging nanotechnology, including photocatalysis, carbon nanodots, and biochar sludges, is discussed. Cost-effective, high-performance, scalable EPS biomaterials are illustrated. Demonstrates sustainable microbial EPS-derived biodevices to remove eco-pollutants and toxicants. EPS-based bioreactors for treating pollutants and wastewater are being explored for future bioresource-based research and technology design.