Effectiveness of ozonation with zirconium and tin tetrachloride for stabilized anaerobic landfill leachate treatment.

Landfill leachate can threaten the environment and human life. Therefore, this study aims to investigate the efficiency of ozone (O ), O with zirconium tetrachloride (O /ZrCl ), and O with tin tetrachloride (O /SnCl ) in remediating the stabilized anaerobic landfill leachate (SAL) from Alor Pongsu, Perak. Hydroxyl radical (OH•) is an important oxidizing agent in the ozonation process. Its presence was tested using tert-butyl alcohol. Results showed that using ZrCl and SnCl in ozonation boosted the generation of hydroxyl radical, thereby enhancing the oxidation process and pollutant removal inside the sample. The O /ZrCl mix at chemical oxygen demand (COD) to ZrCl ratio of 1:1.5, pH 8-9, and 90-min reaction time resulted in the highest reduction rates of COD and color at 91.9% and 99.6%, respectively. All results demonstrated that the optimum performance occurred at alkaline conditions (pH > 8), proving that OH radicals primarily oxidized the pollutants through an indirect reaction pathway. The biodegradability (biochemical oxygen demand/COD) ratio was also considerably improved from 0.02 (raw) to 0.37 using O /ZrCl , compared with using O alone and using O /SnCl , which only recorded 0.23 and 0.28, respectively, after the treatment. The study demonstrated that O /ZrCl was the most efficient combination. PRACTITIONER POINTS: The O /ZrCl recorded the highest COD and color removals. The O /ZrCl combination also recorded higher OH• concentrations. The biodegradability of leachate (BOD /COD ratio) improved from 0.02 to 0.37.