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Landfill leachate is a complex mixture of organic and inorganic compounds, that is generated when water passes through the waste, thus posing a potential pollution problem for local ground and surface waters. Because of highly variable leachate composition, effective and economically efficient leachate treatment methods are difficult to find. For this reason hybrid techniques, which combine two or three oxidation methods can be used with good economics and high degree of efficiency.
In the article, ozone oxidation with hydrodynamic cavitation was applied. The main driving mechanism in the degradation of pollutants using hydrodynamic cavitation is the generation of free radicals in extreme conditions of pressure and temperature. The use of ozone enhances the rates of degradation due to generation of additional free radicals, therefore an amalgamation of the two methods is expected to give synergistic results. Moreover, with regard to practical implementation, a combination of cavitation with ozone offers lower operating costs in comparison to other oxidation techniques, because the operating costs of cavitation include only energy consumption.
Leachate from municipal landfill (Lublin, Poland) was tested in different operative conditions, concentration of ozone and reaction time. Changes in main process parameters such as TOC, COD, BOD and ammonia nitrogen were analyzed. It was found that ozone oxidation combined with hydrodynamic cavitation allows to obtain more satisfactory results than individual oxidation processes applied alone.
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