Performance of combined ozone and zirconium tetrachloride in stabilized landfill leachate treatment

The current study investigated the performance of combined ozonation and zirconium tetrachloride (ZrCl4) for an anaerobic stabilized landfill leachate treatment. The effectiveness of ZrCl4 dosage [COD0/ZrCl4 ratio (g/g)], pH variation, and reaction time during ozonation were evaluated to obtain the optimal operational conditions of ozone (O-3)/ZrCl4 oxidation process. The maximum removal efficiencies for chemical oxygen demand (COD) and color were 88 and 100 %, respectively, at 1/2 g zirconium tetrachloride dosage (COD0/ZrCl4), pH 6, and 90 min reaction time, whereas 79 % removal for ammonia (NH3N) was obtained at pH 11. Biodegradability (BOD5/COD) was improved from 0.07 to 0.09 and 0.34 after treatment with O-3 alone and O-3/ZrCl4, respectively. Treatments using ozonation alone and zirconium alone were performed and compared with the results obtained from the treatment with the new catalytic ozone method (O-3/ZrCl4). The new oxidation method (i.e., O-3/ZrCl4) obtained better removal efficiencies for organic substances and ammonia and this method reported better biodegradability ratio compared with other related processes. The O-3/ZrCl4 process is also more efficient than O-3/Fenton and O-3/persulfate for stabilizing leachate treatment.