Treatment of Tebuthiuron in synthetic and real wastewater using electrochemical flow-by reactor

Abstract

The inefficiency of conventional water treatment methods in the treatment of recalcitrant herbicides has led to the search for new, efficient and eco-friendly mechanisms for degrading these organic pollutants. Electrochemical advanced oxidation processes (EAOP) have emerged as a promising alternative due to their high degree of efficiency in degrading organic pollutants. This work investigates the removal of Tebuthiuron (TBH) in synthetic and real wastewater using different EAOPs in a flow-by reactor. The degradation/mineralization experiments were performed using boron-doped diamond electrode as anode and gas-diffusion electrode (GDE) as cathode for the in situ electrogeneration of hydrogen peroxide (H2O2). For the analysis conducted in synthetic medium, TBH degradation was found to fit well in a pseudo-first-order kinetic reaction with increasing k1 values according to the following order of efficiency: anodic oxidation (AO, 3.1 × 10−5 s−1) < AO with H2O2 generation (AO-H2O2, 4.8 × 10−5 s−1) < electro-Fenton (EF, 5.9 × 10−5 s−1) < AO-H2O2/UVC (2.6 × 10−4 s−1) < photoelectro-Fenton (PEF, 3.2 × 10−4 s−1). AO-H2O2/UVC and PEF processes presented the highest rates of mineralization and similar energy consumption per order (~ 45 kWh m−3 order−1). The degradation experiment conducted using real urban wastewater yielded a 1.7-fold decrease in TBH degradation kinetics compared to the synthetic medium; this difference was attributed to the presence of inorganic ions and natural organic matter in real wastewater which tended to affect the electrochemical system efficiency. The findings of this study are of great interest and confirm the viability of electrochemical techniques for treating complex effluents contaminated by herbicides.