Phytotoxicity and ecotoxicity assessment of landfill leachate treated by UV-Fenton: From lab to pilot scale

The generation of leachate, from the disposal of waste in sanitary landfills, is a major socioeconomic and environmental issue that deserves special attention. The particularly complex composition and the hazardous nature of some pollutants that are present in landfill leachate make evident the necessity of developing effective treatment methods. UV/Fe2+/H2O2 process seems to be a particularly useful tool for removing the organic load, thus reducing the toxicity effect of landfill leachate. In this research paper, such a process was applied in a stabilized and a biologically pretreated leachate sample with the aim of examining the ecotoxicity and phytotoxicity abatement before and after the chemical oxidation. The findings showed that UV-Fenton process can give excellent results, achieving 85.14% COD and 88.35% TOC removals of the stabilized leachate in lab-scale applications and 66.36% COD reduction in pilot-scale application, under the same experimental conditions ([H2O2]:COD = 3:1, [Fe2+ ]/[H2O2] = 1:10, treatment time = 180 min and pH = 3). Additionally, the results from the phytotoxicity tests, using Sorghum saccharatum seeds, revealed that chemical oxidation was able to reduce the toxic effects of landfill leachate, although it couldn't degrade completely the hazardous compounds. Similar conclusions were drawn by ecotoxicity tests with Daphnia magna, whose mortality was markedly lower in the treated samples. The above findings can serve as an adequate basis for future research studies so as to develop efficient treatment approaches.