A comparative assessment of biofiltration and activated sludge diffusion for odour abatement

► AS diffusion systems are a robust and efficient technology for odour treatment in WWTPs. ► High kLa values were recorded in the AS unit (one order of magnitude higher than those reported in biotrickling filters for comparable EBRTs). ► The supply of wastewater to the AS unit seems mandatory for an efficient and robust odour removal. ► The biodiversity of the microbial community present in the AS unit remained surprisingly high despite the limited carbon source fed. ► The biofilter unit was capable of operating at pH as low as 1.8 but the high removal efficiencies were due to the high pressure drop.