Immobilized bacterial cell technology for sustainable industrial wastewater treatment: a review

Immobilization cell systems provides an efficient and environment friendly alternative for the treatment of recalcitrant pollutants present in industrial wastewater. Immobilization of microbial cells can be achieved via various techniques including adsorption on solid surface, encapsulation in semi-permeable polymers and cross-linking with polymeric compounds. It provides high biomass concentration, reusability, mechanical/chemical stability, easy solid-liquid separation, and resilience to harsh effluent conditions. Moreover, some support matrices like nanocomposites and biopolymers may serve the dual role, as an adsorbent as well as an aid in biodegradation/biosorption of target pollutant. Immobilized cell systems have sequestered various contaminants present in industrial wastewater such as; dyes, hydrocarbons, heavy metals, phenol and surfactants. Recent advances in new carriers; biopolymers, nanocomposites, and carbon materials improve bacterial cell stability and improve the pollutant removal efficacy in complex waste streams. This review examines the different strategies available, targeting merits of the immobilized cell system over suspended ones, selection criteria of the support matrix, and critical analysis of the studies conducted using immobilized cell matrices for the treatment of different industrial effluents. Along with pollutants removal, the options for resource recovery/isolation of value-added products from industrial wastewater are also highlighted. Considering limited reports on exploitation of immobilized bacterial cell system for treatment of real industrial wastewaters, and looking into the current and future load of industrial pollution, the comprehensive appraisal of the recent advancement of sustainable bioremediation strategies will promote industrial scalability, cost-efficiency and will contribute to circular economy.