Effect of full and partial-bed configuration on carbon removal performance of biological aerated filters

A comparative study to explore the characteristics of partially and fully packed biological aerated filters (BAFs) in the removal of carbon pollutant, reveals that the partial-bed reactor can perform comparably well with the full-bed reactor. The organic removal rate was 5.34 kg COD m⁻³ d⁻¹ at Organic Loading Rates (OLR) 5.80±0.31 kg COD m⁻³ d⁻¹ for the full-bed, and 5.22 kg COD m⁻³ d⁻¹ at OLR 5.79±0.29 kg COD m⁻³ d⁻¹ for the partial-bed. In the partial-bed system, where the masses of biomass were only 41–51% of those of the full-bed, the maximum carbon removal limit was still between 5 to 6 kg COD m⁻³ d⁻¹. At organic loadings above 5.0 kg COD m⁻³ d⁻¹, the carbon removal capacity in both systems was limited by the mass and activity of microorganisms. The SRT in the full and partial-bed reactors was primarily controlled by the biomass loss in the effluent and during backwash operation. The SRT was reduced from 20.08 days at OLR 4.18±0.20 kg COD m⁻³ d⁻¹ to 7.62 days at OLR 5.80±0.31 kg COD m⁻³ d⁻¹ in the full-bed, and from 7.17 days to 4.21 days in the partial-bed. After all, SRT values in the partial-bed were always lower than those in the full-bed.