Effects of ferric ions on the catalytic ozonation process on sanitary landfill leachates

Abstract

Leachates exhibiting an unstable ratio of biochemical oxygen demand (BOD) and chemical oxygen demand (COD) of approximately 0.45 are typical of new landfills in the City of Cachoeira Paulista, Brazil. Although the organic matter portion is bio-treatable, the presence of refractory leached organic material requires unconventional effluent-treatment processes. Leachate treatment with ozone oxidation, in the presence of ferric ions, acts as catalyst in the formation of hydroxyl radicals. Ozone was obtained by corona-discharge from high-purity O2 gas. The treatment was performed in natura in a jacketed borosilicate glass reactor containing 900 ml of leachate. The analyzed response variable was expressed as the concentration of dissolved organic carbon (DOC). In order to determine the optimal proportions to produce the greatest degradation rate for organic materials, variations in experimental O2 flow-fed to the generator, the Fe(iii) concentration, and the output of the ozonator were conducted over two experimental runs. Experimental models showed a DOC degradation on the order of 81.25%.