Advanced oxidation of bio-treated incineration leachate by persulfate combined with heat, UV254 nm, and UV365 nm: Kinetics, mechanism, and toxicity

This study compared and evaluated the ultraviolet/persulfate (UV/PS) at 254 or 365 nm and heat/persulfate (heat/PS) systems for advanced treatment of biologically pre-treated incineration leachate. The UV365 nm/PS system with the highest removal reduced chemical oxygen demand (COD) by 81.7%, total organic carbon by 73.8%, NH3-N by 96.8%, total nitrogen by 47.3%, and color by 98.6% within 24 h, separately. Kinetics tests suggested that a highest concentrations of 4.8 x 10(-10) M for [SO4 center dot-](ss) and 2.8 x 10(-11) M for [center dot OH](ss) were reported in UV365/PS and UV254/PS systems, respectively. Characterization of leachate organic matter species revealed that low molecular weight organic matter < 5 kDa was preferentially degraded in three systems. Ketones are relatively easily degraded by both heat/PS and UV/PS systems, whereas esters were the most recalcitrant. Three-dimensional fluorescence analysis revealed > 99% humic acid and fulvic acid removal in all three systems. In practical applications, it is crucial to consider the pH and toxicity of SR-AOPs in the treatment of bio-treated incineration leachate. Furthermore, the ecotoxicity of MBR effluent treated by the heat/PS system and UV365 (nm)/PS system increased, which was caused by the strong acidity exhibited in the systems. In addition, we found that PS could interfere with 3.3% of the COD's detection. The findings of this study suggest that secondary effects of PS on water quality at high doses should be investigated in future research.

Automated summary

This study compares and evaluates the UV/PS and heat/PS systems for advanced treatment of biologically pre-treated incineration leachate. The results show that the UV365 nm/PS system has the highest removal efficiency for various pollutants. Moreover, the study highlights the potential interference of PS on COD detection.