A systematic literature review of biocarriers: central elements for biofilm formation, organic and nutrients removal in sequencing batch biofilm reactor

Over the past decades, several materials utilized as biocarriers for immobilization of microorganisms have been gaining popularity showing different degrees of effectiveness. However, information concerning their effects on sequencing batch biofilm reactors (SBBR) performance is still lacking. There is currently no single widely acceptable material documented for proper biofilm formation, as most materials cannot achieve satisfactory level. Problems of biocarrier also exists due to the emergence of newer and more complex pollutants. Therefore, resource-efficient and environmentally friendly biocarriers are a call of the hour. This article thus, presents a systematic literature review of existing research articles on the various advances made between 2005 and 2021 about biocarrier physical properties, and performances with specific focus on their contributions in biofilm formation, nutrients and organic matter removal. This is to establish their role as central elements in biofilm formation. The review further described the operational challenges, mass transfer considerations, and recommendations made during successful utilization of the biocarriers in SBBR systems. Future research areas that may ultimately lead to large-scale commercial application of this biocarriers and will result in sustainable and environmentally friendly solution to the problems created during wastewater treatment have also been identified. This paper suggests that future researchers investigate the efficiency of composite biocarriers. It is believed that information contained in this review will increase readers fundamental knowledge, guide future researchers and be incorporated into future works on experimentally-based studies on biocarriers in SBBR systems.