A pilot study on the regeneration of ferrous chelate complex in NOx scrubber solution by a biofilm electrode reactor

A chemical absorption-biological reduction integrated process has been proposed for the removal of nitrogen oxides (NOx) from flue gases. In this study, we report a new approach using biofilm electrode reactor (BER) to regenerate Fe(II)EDTA via simultaneously reducing Fe(II)EDTA-NO and Fe(III)EDTA in NOx scrubber solution. Biofilm formed on the surface of the cathode was confirmed by Environmental Scan Electro-Microscope. Experimental results demonstrated that it was effective and feasible to utilize the BER to promote the reduction of Fe(II)EDTA-NO and Fe(III)EDTA simultaneously. The reduction efficiency of Fe(II)EDTA-NO and Fe(III)EDTA was up to 85% and 78%, respectively when the BER was continuously operated with electricity current at 30 mA. The absence of electricity induced an immediate decrease in reduction efficiency, indicating that the bio-regeneration of ferrous chelate complex was electrochemically accelerated. The present approach is considered advantageous for the enhanced bio-reduction in the NOx scrubber solution.