Immobilized biomass systems: an approach for trace organics removal from wastewater and environmental remediation

Immobilization of biomass, i.e. entrapment of live or dead microbes on support materials or within a matrix, most commonly using a polymer matrix has been in use for wastewater treatment. A variety of mixed as well as isolated cultures of bacteria, algae, fungi, and yeast were used for remediation of pollutants from different matrices. The major mechanism of pollutant removal by immobilized biomass was via adsorption, biosorption, biodegradation, bioprecipitation, etc. The immobilized systems were found to be more efficient than suspended biomass systems, and as a result, several investigations have been carried out for the removal of heavy metals, polycyclic aromatic hydrocarbons, pesticides, and other trace organics removal. However, the life and reusability of the support matrices for immobilization, effect of citrates and phosphates in feed on encapsulated polymer beads, and large-scale production of biomass are the key challenges faced in the promotion of encapsulated biomass for field-scale application. This review outlines the immobilization techniques, materials used for immobilization of biomass, and factors affecting the performance of the immobilized and encapsulated biomass systems for trace organics removal. Moreover, the applicability of immobilized systems in bench-scale studies, their major limitations, and future research direction were emphasized.