Simultaneous removal of sulphur dioxide and nitric oxide at different oxygen concentrations in a thermophilic biotrickling filter (BTF): Evaluation of removal efficiency, intermediates interaction and characterisation of microbial communities.

Simultaneous flue gas desulphurisation and denitrification in biotrickling filter was investigated under different O2 concentrations (0%, 3%, 5%, 8% and 10%) at 45 °C. NO and SO2 removal efficiency, intermediates (NO3-, NO2-, NO2, SO42- and S2-) interaction and accumulation, S0 recovery and microbial community structure were investigated. Results indicated the highest NO removal efficiency was 96.5% at 5% O2. Maximum SO2 removal efficiency was 95.6% at 3% O2. Moreover, N intermediates accumulation increased when O2 concentration increased from 0% to 10%. The lowest S2- concentration of 61 mg/L and the maximum S0 recovery of 76.9% were achieved at 5% O2. The bioreactor at 10% O2 contained less bacterial OTUs richness and evenness compared with other conditions. Illumina analysis indicated Proteobacteria, Firmicutes and Bacteroidetes were the dominant members. Overall, microbial community structure differs significantly under different O2 concentrations.