Landfill leachate treatment by batch supercritical water oxidation

Municipal solid waste leachate, a kind of wastewater, can severely damage the environment and contaminate the groundwater because of its high organic matter and toxic heavy metal concentrations. Due to its complex composition, this wastewater must be properly treated prior to being discharged into the environment. In recent decades, several biological approaches (e.g., bioremediation, phytoremediation, and bioreactors) and physicochemical processes (e.g., coagulation/flocculation, air stripping, and advanced oxidation processes) have proven effective at removing the organic load and the toxicity of this effluent. Physicochemical treatments have been applied as pretreatment or post-treatment steps for biological processes, but these methods do not always provide satisfactory results and can cause secondary pollution in some cases. In addition, owing to the high concentrations of organic matter, ammonia, and trace metals in landfill leachate, combined approaches to leachate treatment have been reported to be efficient. This article highlights the advantages and drawbacks of these approaches to the treatment of leachate by providing an updated overview of the various methods that have been successfully applied in this field. Further studies should focus on improving landfill leachate treatment to maximize removal performance.

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Modeling and simulation of hydrothermal oxidation of cutting oil in supercritical water

Benmakhlouf

Outili

Sánchez-Oneto

et al. 2020

International Journal of Chemical Reactor Engineering

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Supercritical water oxidation may be used as waste treatment technique that consists of oxidizing organic and inorganic matter using water at supercritical conditions. It was developed as an alternative technique in order to limit the risks of secondary pollution. The purpose of this study is the development of simulation tools in stationary state in supercritical water oxidation (SCWO) tubular reactor which has been numerically investigated basing on using a two-dimensional modeling approach applying the k-ε turbulence model, and on the international association for the properties of water and steam formulation (IAPWS-IF97). A Multiphysics simulation using Comsol Multiphysics 5.2 software for the supercritical water oxidation of “cutting oil Biocut 35” as a pollutant is reported. First, the heat transfer coefficient was estimated and the obtained temperature and species concentration profiles were compared to experimental data where a quite good agreement was obtained as confirmed by the acceptable coefficient of determination value. Finally, once the used model was validated, numerical simulations were performed to describe the behavior of the reactor investigating the effects of operating conditions such as temperature, pollutant feed concentration and reactor inlet flow rate, on dependent variables like outlet temperature, chemical oxygen demand removal (COD) and the highest temperature reached inside the reactor. This last parameter was considered in the study to take into account the operation safety. The significance of the studied factors and their interactions were quantified and analyzed by means of the full factorial design of experiment (DOE). The results showed that the effect of initial temperature was the most important for the three responses, followed by the feed concentration then to a lesser extent the flow rate. The effect of initial temperature was positive for outlet temperature, maximal temperature and cutting oil removal. The interaction temperature-feed concentration was the only significant one for the COD removal and the maximal temperature. The results defined an operation safety zone of the SCWO reactor based on the superposition of the three studied dependent variables and imposed constraints on the inside reactor temperature and the pollutant outlet concentration.

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Landfill leachate treatment by batch supercritical water oxidation

Cited by 4 publications

References 32 publications

Status and Challenges of Determining Sustainable Technology of Landfill Leachate Treatment on Municipal Solid Waste (MSW): An Update

Status and Challenges of Determining Sustainable Technology of Landfill Leachate Treatment on Municipal Solid Waste (MSW): An Update

Recent technologies for leachate treatment: a review

Modeling and simulation of hydrothermal oxidation of cutting oil in supercritical water

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