Response of biofilm–based systems for antibiotics removal from wastewater: Resource efficiency and process resiliency

Abstract

Biofilm–based systems have efficient stability to cope–up influent shock loading with protective and abundant microbial assemblage, which are extensively exploited for biodegradation of recalcitrant antibiotics from wastewater. The system performance is subject to biofilm types, chemical composition, growth and thickness maintenance. The present study elaborates discussion on different type of biofilms and their formation mechanism involving extracellular polymeric substances secreted by microbes when exposed to antibiotics–laden wastewater. The biofilm models applied for estimation/prediction of biofilm–based systems performance are explored to classify the application feasibility. Further, the critical review of antibiotics removal efficiency, design and operation of different biofilm–based systems (e.g. rotating biological contactor, membrane biofilm bioreactor etc.) is performed. Extending the information on effect of various process parameters (e.g. hydraulic retention time, pH, biocarrier filling ratio etc.), the microbial community dynamics responsible of antibiotics biodegradation in biofilms, the technological problems, related prospective and key future research directions are demonstrated. The biofilm–based system with biocarriers filling ratio of ∼50–70% and predominantly enriched with bacterial species of phylum Proteobacteria protected under biofilm thickness of ∼1600 μm is effectively utilized for antibiotic biodegradation (>90%) when operated at DO concentration ≥3 mg/L. The C/N ratio ≥1 is best suitable condition to eliminate antibiotic pollution from biofilm–based systems. Considering the significance of biofilm–based systems, this review study could be beneficial for the researchers targeting to develop sustainable biofilm–based technologies with feasible regulatory strategies for treatment of mixed antibiotics–laden real wastewater.