Phosphate removal from aqueous solution using slag and fly ash

Abstract

The application of low cost materials in wastewater treatment has recently attracted great interest; fly ash and slag have improved high performance as a low cost material and have been used as a potential adsorbent for removal of phosphate, heavy metals and organic pollutants in wastewater treatment. Batch adsorption experiments were performed in order to evaluate phosphate removal efficiency of slag and fly ash. The effect of various operating variables, i.e. initial pH, adsorbent dose, initial metal ion concentration, and adsorption time of phosphate using the slag and fly ash, has been studied. The sorption process was relatively fast and equilibrium has been reached at 30min contact time and the maximum removal percentage was achieved at an adsorbent loading weight of 0.5gm/100ml. Phosphate removal ratio using slag and fly ash was 93% and 95%, respectively, under the batch test conditions. The overall uptake for the slag was maximum at pH 5 and at pH 7 for fly ash. The sorption data were represented using Freundlich and Langmuir parameters, where the sorption data were better represented by the Freundlich isotherm than by the Langmuir. The optimized method was applied for phosphate removal from wastewater of Proctor and Gamble (P&G) Company for household products. The achieved phosphate removal efficiency was 96.15% and 96.9% using slag and fly ash respectively.