Fe-C micro-electrolysis-electrocoagulation based on BFDA in the pre-treatment of landfill leachate: Enhanced mechanism and electrode decay monitoring

Abstract

In this research, a composite electrode for blast furnace dust ash (BFDA) was proposed in landfill leachate pre-treatment by Fe-C micro-electrolysis and electrocoagulation. To verify the effect of Fe-C micro-electrolysis, EC and Fe-C-EC systems were established respectively. When the voltage was 0.5 V–15 V and the electrode distance was 1 cm, the removal rates of COD and NH4+-N in the landfill leachate by the composite system were 18.74%–43.6% and 5.48%–13.8%, respectively, which were 12.18%–5.3% and 3.03%–1.1% higher than the electrocoagulation system. By making a comparison between the two anode passivation layers' compositions, the mechanism of Fe-C micro-electrolysis was determined. The continuous supply of Fe2+ results in an increase on Fe3O4 and reduction in the harmfulness of the passivation layer. With the ultrasonic time-domain reflectometry(UTDR) analysis, the formation process of the anode passivation layer in the composite system was under monitoring, thus clarifying the best polarity reversal start time (PRST) and polarity reversal operational time (PROT) for the next polarity reversion measures. In this study, a new method for BFDA reclamation together with an efficient way for electrode passivation recovering were proposed.