Isotherm modelling for the treatment of wastewater using a fly ash-based coagulant

The mining industry consumes large amounts of water and produces large volumes of wastewater that may cause detrimental environmental pollution if discharged directly due to its high concentrations of harmful metal ions. In the present study, the performance of a coal fly ash-based coagulant was investigated in removing total dissolved solids, Mn, Mg, and Si, from mining effluent. The coagulation process was conducted at pH 7 with varying coagulant dosage, temperature, and coagulation time. Results indicated that the coal fly ash-based coagulant efficiently eliminates the investigated impurities from wastewater. Compositional analyses of the sludge produced showed that adsorption occurred during coagulation. The coagulation adsorption mechanisms for the removal of Mn, Mg, and Si from mine wastewater were investigated based on Langmuir, Freundlich, Temkin, and BET isotherm models. Coagulation adsorptions were found to be exothermic processes, as suggested by the Temkin and BET isotherm models. The best-described adsorption isotherm model was found to be Temkin and BET. This type of coagulant can easily be adopted for use in mine effluent treatment plants, helping to reduce the pollution problems associated with mine wastewater.