Microorganisms-carbonaceous materials immobilized complexes: Synthesis, adaptability and environmental applications

Microbial remediation is an inherently eco-friendly and promising approach, if it can be implemented properly. One important approach advancing microbial remediation is the immobilization technology with carbonaceous materials (CMs), i.e., biochar, activated carbon, carbon nanotubes, graphene, and its derivatives as carriers. Carbonaceous carriers for functional microbes pyramid the advantages of highly-efficient physiochemical sorption and microbial metabolisms. This review focuses on the synthesis of microorganisms (e.g., metal-resistant microorganisms and organic pollutant-degraders)-CMs immobilized complexes (McMICs) and their potential applications in environmental pollution control. Among different CMs, biochar and activated carbon have been popularly utilized for cell immobilization due to their low toxicity and abundant feedstock. Immobilized cells normally exhibit higher removal efficiency for a variety of pollutants than CMs alone or free cells. The immobilization of metal-tolerant microorganisms on CMs could directly enhance metals removal efficiencies or indirectly ameliorate soil contamination by promoting the phytoremediation effect. Particularly, immobilized cells have been extensively applied in the treatment of organic pollutants. The removal efficiency of McMICs could be enhanced more than 8-fold synergistically by physiochemical sorption and microbial degradation as reported. Studies have also placed an emphasis on the roles of key determining factors like temperature and pH in the relevant bioremediation processes. Importantly, McMICs possessed higher stability than free cells and excellent reusability in bioremediation processes. Future challenges in this area include the selection of novel, effective and low-cost carbonaceous carriers and expansion of McMICs’s environmental applications. Overall, this work improves our understanding of engineering pathways to the industrial applications of McMICs. • Biochar and activated carbon were widely utilized for cell immobilization. • Immobilized cells normally exhibited higher removal efficiency for various pollutants than CMs alone or free cells. • Immobilized cells possessed higher stability and excellent reusability than free cells.