Landfill leachate treatment by a photoassisted fenton reaction

Abstract

A combination of the classical Fenton reaction (Fe(II)+H2O2) with UV light, the photoassisted Fenton reaction, has been investigated for the treatment of landfill leachate. The investigation has been carried out with an experimental set-up to establish the optimal treatment conditions. The degradation rate of organic pollutants is strongly promoted by the photoassisted Fenton reaction. The degradation rate depends on the amount of H2O2 and Fe(II) added, pH value, and radiation intensity. At a specific energy input of 80 kW m−3 the oxidation rate was increased to six times the rate without radiation (0 kW m−3). At the higher radiation intensity of 160 kW m−3 the degradation rate was about two times faster than at that of 80 kW m−3. Due to the regeneration of the consumed Fe(II) ions through the irradiation, the amount of ferrous salt to be added can be remarkably reduced. The optimum conditions were obtained with 1.0 × 10−3 mol 1−1 Fe(II) added, a pH value of 3, and a molar ratio of COD: H2O2 = 1:1. At a COD volume loading of less than 0.6 kg m−3 h−1, a COD degradation of more than 70% could be obtained with an energy input of 80 kW m−3.

Removal of 1,4-dioxane from industrial wastewaters: Routes of decomposition under different operational conditions to determine the ozone oxidation capacity

“…The pH was controlled throughout the experiment by adding NaOH when needed to keep it at the set value, except the experiments with the single addition of NaHCO3 buffer (11.9 mM) that caused the pH to increase from 9.0±0.1 to 10.0±0.1 during the experimental run. Additional experiments were carried out adding H2O2 at the stoichiometric ratio proposed by Kim et al [37] (1gL -1 chemical oxygen demand (COD) = 2.125gL -1 H2O2). Optimal conditions were applied to treat three actual industrial wastewaters (Samples 1-3, Table 1) that were still contaminated with 1,4-dioxane and 2-methyl-1,3-dioxolane (MDO) after a biological treatment step of a particular factory.…”

Advanced Oxidation Processes (AOPs) in Wastewater Treatment

“…However, limited success was accomplished because leachate contaminants are typically more complex and recalcitrant than sewage. In the 1990s, AOPs were first applied for treatment of landfill leachate, particularly mature or biologically stabilized leachate [33][34][35][36]. The primary purpose of AOP application includes the following: (1) to increase the biodegradability of organics for following biological treatment, (2) to directly remove organic constituents, or (3) to further degrade organics as a post-treatment unit for other technologies [37,38].…”

Fundamentos e aplicações ambientais dos processos fenton e foto-fenton

“…A DQO remanescente pode ser eficientemente mineralizada por processos biológicos 77 . Kim e colaboradores 65 e Lopez e colaboradores 66 apresentaram resultados semelhantes na degradação de chorume, em que 60% do COT foi removido por processo foto-Fenton e o restante foi mineralizado biologicamente. Também é muito comum o uso dos processos Fenton/foto-Fenton combinados a processos físico-químicos como acontece nas indús-trias têxteis, onde inicialmente o material particulado e metais são removidos do efluente e posteriormente são aplicados os processos Fenton/foto-Fenton para remoção de cor, COT, odor 59 .…”