Exploring alkali-treated corn cob for high-rate removal of NOX and SO2 from flue gas: Focus on carbon release capacity, removal performance, and comparison with conventional carbon sources.

ABSTRACT

This investigation explored the potential of utilizing alkali-treated corn cob (CC) as a solid carbon source to improve NOX and SO2 removal from flue gas. Leaching experiments unveiled a hierarchy of chemical oxygen demand release capacity 0.03 mol/L alkali-treated CC > 0.02 mol/L > 0.01 mol/L > 0.005 mol/L > control. In NOX and SO2 removal experiments, as the inlet NOX concentration rose from 300 to 1000 mg/m3, the average NOX removal efficiency increased from 58.56 % to 80.00 %. Conversely, SO2 removal efficiency decreased from 99.96 % to 91.05 %, but swiftly rebounded to 98.56 % by day 18. The accumulation of N intermediates (NH4+, NO3-, NO2-) increased with escalating inlet NOX concentration, while the accumulation of S intermediates (SO42-, SO32-, S0) varied based on shifts in the population of functional bacteria. The elevation in inlet NOX concentration stimulated the growth of denitrifying bacteria, enhancing NOX removal efficiency. Concurrently, the population of nitrate-reducing sulfur-oxidizing bacteria and sulfate-reducing bacteria expanded, aiding in the accumulation of S0 and the removal of SO2. The comparison experiments on carbon sources confirmed the comparable NOX and SO2 removal efficiencies of alkali-treated CC and glucose, yet underscored differences in intermediates accumulation due to distinct genus structures.