A Novel High Capacity Biofilm Reactor System for Treatment of Domestic Sewage

Abstract

A lab-scale novel biofilm reactor system, Ultra-Compact Biofilm Reactor (UCBR), was studied to investigate its performance and operational characteristics for domestic sewage treatment. The reactor was operated at four different hydraulic retention times, namely, 90, 60, 30 and 15 min. The operating ranges of volumetric loading rates in terms of COD, BOD5, NH+4-N and TKN were 5.6-62.1 kg COD/m3 d, 2.6-32.5 BOD5/m3 d, 0.6-3.2 kg NH+4-N/m3 d and 0.82-6.2 kg TKN/m3 d, respectively. The COD, BOD5 and NH+4-N removal efficiencies at 90-min hydraulic retention time (HRT) and 60-min HRT could exceed 80%, 90% and 99%, respectively. The corresponding maximum biomass concentrations were 12.0 g/L and 15.0 g/L at 90-min HRT and 60-min HRT, respectively. At 30-min HRT, the biomass concentration increased to a maximum of 24.0 g/L. However, COD and BOD5 removal efficiencies decreased to 75% and 80%, respectively, while the NH+4-N nitrification efficiency decreased to only 25% to 30%. These observations suggested that high biomass concentration alone was not sufficient to provide a high removal capacity in a UCBR. Further reduction in HRT to 15 min led to an excessive biomass decline from 22.5 g/L to 4.0 g/L. On the whole, the UCBR was able to sustain COD removal and NH+4-N conversion of up to 5.96-18.70 kg COD/m3 d and 0.73-1.00 kg NH+4-N/m3 d, respectively.