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.