New approach for the inhibition of PCDD/F formation in fly ash by carbohydrazide during refuse-derived fuel (RDF) combustion

PCDD/Fs in fly ash from municipal solid waste incineration (MSWI), pose significant health and environmental risks. Recent research has focused on using chemical inhibitors in the post-combustion zone to effectively inhibit PCDD/F formation. This study examined a new inhibitor, carbohydrazide (CHZ), by exploring its application techniques and mechanism for PCDD/F inhibition. A comparative analysis was conducted to identify the efficient CHZ addition method, by comparing the PCDD/F suppression effect by CHZ premixing and cofiring with refuse-derived fuel (RDF) and injecting into the flue gas. It was revealed that the premixing and cofiring of CHZ with RDF resulted in a 10.9% reduction in the formation of PCDD/Fs, demonstrating the effectiveness of the suppression of PCDD/F emissions. XRD analysis showed that the addition of CHZ led to the reduction of CuO to Cu₂O in bottom and fly ash, and thus deactivate the Cu-based catalysts. In addition, CHZ could also passivate the transition metal catalysts through coordination. Consequently, CHZ could be considered as a potential PCDD/F inhibitor during the combustion process.