Biofiltration for treatment of recent emerging contaminants in water: Current and future perspectives

Abstract This review article discusses the current state of knowledge on water treatment and reuse by biofiltration systems focusing on biologically enhanced activated carbon (BAC) process. First, the applications of BAC in water treatment systems are overviewed, and then, the mechanisms for both biofilm formation and contaminant treatment are discussed along with the operational parameters influencing the performance of BAC process. Since contaminant removal by BAC is governed by adsorption and biodegradation, both processes are reviewed in relation to the treatment mechanisms. Information on removal of recent emerging contaminants including nitrogenous and unregulated disinfection by‐products (DBPs) and their precursors, poly‐ and perfluorofluoroalkyl substances, nanoparticles, and plasticizers and microplastics by BAC is given along with suggestions for treatment improvements and future research. The uniqueness of this review includes insights on relevant biofilm aspects and the coverage on the abilities of BAC for treatment of recent and less common emerging contaminants especially unregulated DBPs and their precursors, nanoparticles, and plasticizers and microplastics. For future BAC studies, recommendations are proposed on exploring the biofilm development on media and recent emerging contaminants as co‐contaminants, as well as developing novel supporting materials such as biochar. Practitioner points The amount and the physiology and physical structure of biofilm affect the treatment efficiency of biological activated carbon. Biological activated carbon is capable of removing a majority of nitrogenous and unregulated disinfection by‐products. Whether and how biological activated carbon is impacted by and/or can remove nanoparticles, and plasticizers and microplastics remain largely unknown. Future work on biological activated carbon should focus on biofilm evolution and control, and novel support materials.