Ti/RuO2-IrO2 anodic electrochemical oxidation composting leachate biochemical effluent: Response surface optimization and failure mechanism.

In this work, the electrolytic process conditions for the electrochemical oxidation (EO) of composting leachate biochemical effluent (CLBE) were optimized via the response surface methodology (RSM). Meanwhile, a comparative study had been done on the failure characteristics of Ti/RuO 2 –IrO 2 anodes in a single electrolyte solution system (H 2 SO 4 and NaCl) and real wastewater (CLBE) by accelerated life tests, respectively. The RSM optimization results showed that the COD, NH 3 –N and TN removal rates were 50.53%, 100% and 95.61% at 30 min, respectively, with a desirability value of 0.993. In parallel, the electrochemical and material characterizations were carried out on the electrodes before and after failure, by which the failure mechanism of Ti/RuO 2 –IrO 2 anodes was clarified. On the whole, the true failure in the H 2 SO 4 solution was attributed to coating dissolution and Ti substrate oxidation. In contrast, the electrode exhibited "apparent failure" due to the "bubble effect" in both NaCl and CLBE solutions, and the "effective roughness" formed compensated for the loss of activity caused by the absence of the coating. Besides, additional dissolution of the Ti substrate occurred in the CLBE solution due to the current edge effect and the presence of organic matter. This paper takes the actual wastewater as the research object and reveals its electrode failure mechanism, which provides a theoretical basis and reference for the subsequent optimization of the actual electrode service life. [Display omitted] • ANOVA indicating that the model equations were well matched with the actual results. • The order of influence of the variables was current density > Cl− concentration > pH. • NH 3 –N and TN removal 100% and 95.61% at 30 min, COD removal 100% after 40 min. • Ti/RuO 2 –IrO 2 electrode exhibited "apparent failure" in actual wastewater (CLBE). • Current edge effect and organic matter led to the dissolution of Ti substrate in CLBE. [ABSTRACT FROM AUTHOR]