New trend of Jebel Chakir landfill leachate pre-treatment by photocatalytic TiO2/Ag nanocomposite prior to fermentation using Candida tropicalis strain

The current study investigates the technical applicability of a combination of photocatalytic process with TiO2/Ag nanocomposite and the biological treatment using Candida tropicalis strain for pollutants removal from mature Jebel Chakir landfill leachate (LFL) under visible light irradiation (33Wcm(-2)). Interestingly, after the nanocomposite treatment, the degradation rate achieved under the optimum conditions 70, 71.25 and 49.1% for COD, TOC, and NH4+-N, respectively. Thereafter, the biological process was applied as a second treatment stage in order to enhance the quality of pre-treated LFL. About 90% of COD, 84.61% of TOC and 75% of NH4+-N were removed after the combined process. Furthermore, heavy metals, especially, Fe, Zn, Cu, Cd, and Pb were significantly reduced with the average removal rates of 50, 63.8, 83, 95 and 95%, respectively. The photocatalytic efficiency in organic pollutants removal was consistently higher than 60% after five cycles without any evident change and deactivation of nanocomposite. The overall results proved that TiO2/Ag exhibited an important photocatalytic activity and an excellent recyclability. In addition, the combination of TiO2/Ag photocatalytic process with biological treatment by C. tropicalis for toxic compounds removal from mature LFL may provide a more comprehensive potential for mature LFL treatment.