An integrated biological system for air pollution control in WtE plants and interaction between NO reduction and toluene oxidation

The abatement of NO and VOCs in the flue gas from WtE plants is of great significance for improving the atmospheric environmental quality at present. In this study, a device of absorption-bioreactor coupling biotrickling-filter (ABR-BTF) was built to realize the simultaneous removal of NO and VOCs, in which the chemical absorption-bioreactor (ABR) was used for reducing NO and the biotrickling-filter (BTF) was employed for eliminating toluene. When the simulated flue gas containing 400 mg m−3 NO and 150 mg m−3 toluene passed through the system for 30 s, the removal efficiency of NO and toluene reached 85% and 90%, respectively. In contrast with the single ABR segment, the loss rate of NO complexing absorber was reduced by 85% in ABR-BTF. Meanwhile, a variety of novel bacterial genera in the field of biological denitrification and VOCs elimination were discovered within the integrated system biome. Thereinto, Candidatus_Cloacamonas and Syntrophomonas produced the hydrogen, which could as electron donors be consumed by the dissolved oxygen species during the process of VOCs degradation, promoting the biological reduction and reducing the loss rate of complexing absorbent in the ABR portion. Meanwhile, Tisierella and Desulfitobacterium could reduce sulfite to S2−, so that part of the complexing absorbent was transformed into FeS and re-entered into the circulation system through the redox reaction with Fe(III). The integrated biological purification system can efficiently remove NO and VOCs simultaneously, and overcome the problems of insufficient microbial reduction rate for poor hydrophobic VOCs, which will provide a fundamental for the optimization and industrial application of the biological technology in WtE plants flue gas treatment.