Odor removal via high-speed biofiltration in headwork operations of wastewater treatment plants

Biofiltration process has proved being an effective, low-cost, and environmental friendly method to remove odor pollution in wastewater treatment plants (WWTPs). Despite its assets, this technology is often limited due to the required surface area for biofilters. The main aim of this study was to study the biofiltration of foul air at high velocities (or low empty bed retention time, EBRT) as an option to reduce the surface area requirement of the deodorization process. To do so, a pilot-scale biofilter was built and operated with foul air coming from the headworks of a WWTP located at Cannes (France) at velocities ranged from 500 to 1400 m/h equivalent to 10-4 s of EBRT, respectively. The concentrations of pollutants ranged from 0 to 140.75 mg/m³ H₂S and from 0 to 21.5 mg/m³ NH₃. Overall, the removal efficiency was between 87.5 and 98.9% for H₂S, and for NH₃ removal was between 51.0 and 96.9%. Odor analyses showed average removal efficiencies above 80%. The impact of high air velocity over the pressure drops was also studied.