Study on NOx removal from simulated flue gas by an electrobiofilm reactor: EDTA-ferrous regeneration and biological kinetics mechanism

Abstract

The regeneration of EDTA-FeII is a key step in electrobiofilm reduction-integrated systems for NOx removal from industrial boiler flue gas. The current and carbon sources are proposed to be the two crucial electron donors for EDTA-FeII regeneration. These parameters strongly influence the reactivity of EDTA-FeII-generated products in the system. Therefore, their effects on EDTA-FeII-NO and EDTA-FeIII reduction and the EDTA-FeII generation mechanism were studied. The results showed that the electrobiofilm method has obvious advantages over biological or electrochemical methods used alone for EDTA-FeII regeneration. Under the optimal conditions at a current of 22.9A m-3 net cathode chamber, the rate of EDTA-FeII regeneration reached 98.35%. The glucose concentration is the primary factor influencing the reduction of both EDTA-FeII-NO and EDTA-FeIII, while the current significantly promotes both processes. Comparison of the Km values of the two substrates indicated that microbial activity was crucial to the reduction of EDTA-FeII-NO, but the biological reduction of EDTA-FeIII had a competitive influence on EDTA-FeII-NO reduction, which limited the abundance and effectiveness of the bacteria responsible for EDTA-FeII-NO reduction in the electrobiofilm system.