High-efficiency removal of NOx by a novel integrated chemical absorption and two-stage bioreduction process using magnetically stabilized fluidized bed reactors

To enhance the bioregeneration of Fe（II）EDTA and to avoid the inhibition of the components in nitrogen oxides（NOx） scrubbing solution, a novel integrated process of metal chelate absorption and two-stage bioreduction was developed. In this process, magnetically stabilized fluidized beds（MSFB） were used as the bioreactors, and the phase diagram for the MSFB operation was determined. Factors including inlet NO, O2 and SO2 concentrations, magnetic field intensity, gas flow rate and liquid circulation rate, were studied experimentally to investigate their effects on NO removal. In addition, a mathematical model for NO removal in this integrated system was developed. The results revealed that the integrated system could be steadily operated with a high NO removal efficiency and elimination capacity, even under the condition of high NO and O2 shock-loading. The established model showed that NO removal efficiency was related to the spray column property and the active Fe（II）EDTA concentration, while the latter depends on the bioregeneration of the disabled absorbent in the MSFB.