Iron Coated-Sand from Acid Mine Drainage Waste for Being a Catalytic Oxidant Towards Municipal Wastewater Remediation

Abstract

The accessibility of clean water and green environment are the major requirements for survival and sustainable development. In this study, iron-coated sand, derived from acid mine drainage effluent, has been applied as a heterogeneous catalyst. Treatment with H2O2, iron-coated sand, and iron-coated sand-Fenton processes is compared for the COD removals from municipal wastewater effluent. The results showed that the iron-coated sand catalyzed Fenton process could generate hydroxyl radicals (•OH) and oxidize the organic pollutants. Fenton process based on the iron-coated sand catalyst proved to be the most efficient process. The effect of operating conditions such as initial pH and Fenton’s reagent doses, i.e. initial H2O2 and iron on the organics oxidation from such wastewater was investigated. The results showed that 70% removal efficiency of COD was obtained within 30 min under optimized conditions (pH 3.0, H2O2 400 mg/L and iron 40 mg/L). The rate equation of iron-coated sand-Fenton system was simply expressed by the second-order equation and the model was found to fit well the data. Thermodynamic analysis of the results indicated that the iron-coated sand-Fenton oxidation is non-spontaneous and endothermic in nature. Regeneration of iron-coated sand was attempted and the catalyst had a good stability and reusability for successive treatments and reducing the quantity of sludge produced in Fenton reactions. Thus, expanding the sustainability scope of iron-coated sand based Fenton catalyst and offer new sustainable and inexpensive alternatives for the classical Fenton process.