Critical review of adsorption and biodegradation mechanisms for removal of biogenic taste and odour compounds in granular and biological activated carbon contactors

Current knowledge on the physical, chemical and biological mechanisms involved in the removal of biogenic taste and odour (T&O) compounds by granular and biological activated carbon (GAC and BAC, respectively) contactors in the context of drinking water treatment is critically reviewed. It is determined that the removal mechanisms, such as physiosorption in the micropore region, kinetic parameters and influence of carbon characteristics on adsorption onto fresh GAC have been well studied and understood. However, it was identified that the parameters that influence the development and performance of the biofilm in BAC, and how operational conditions and carbon characteristics affect these biological processes needs further research. In this review, microorganisms responsible for biological degradation were highlighted and sorted. Pore surface diffusion model was identified as effective at modelling the biofiltration process. Future studies should also focus on the adsorption and biofiltration of T&O compounds other than geosmin and 2-methylisoborneol (MIB) the isolation and characterisation of microorganisms capable of biodegrading T&O compounds in active BAC contactors, and the identification of the biodegradation pathways and by-products in large scale systems.