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/RuO2-IrO2 anodes in a single electrolyte solution system (H2SO4 and NaCl) and real wastewater (CLBE) by accelerated life tests, respectively. The RSM optimization results showed that the COD, NH3-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 character-izations were carried out on the electrodes before and after failure, by which the failure mechanism of Ti/ RuO2-IrO2 anodes was clarified. On the whole, the true failure in the H2SO4 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 ac-tivity 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.

Automated summary

The electrolytic process conditions for the electrochemical oxidation (EO) of composting leachate biochemical effluent (CLBE) were optimized using the response surface methodology (RSM). Comparative studies were conducted to investigate the failure characteristics of Ti/RuO2-IrO2 anodes in different electrolyte solutions. The optimization results showed a high removal rate for COD, NH3-N, and TN, and the failure mechanism of the Ti/RuO2-IrO2 anodes was clarified through electrochemical and material characterizations.