Application of Modified Clay Mineral Waste Material for Removal of Phosphorus from Aquatic System

Abstract

Phosphorus (P) is one of the major components causing eutrophication in the aquatic systems. This study examined the application of modified clay mineral waste material (MCMWM) for removal of P from aquatic systems including surface water and wastewater. The effects of ionic strength and pH on P adsorption by MCMWM were investigated at pH values of 3, 5, 6, 7 and 9 with P concentrations of 10, 20, 40, 100 and 200 mg/L in solution. The P adsorption was rapidly at the early stage with 95% of P in solution being adsorbed for 10 mg/L P in solution at a high pH range within 0.5 hr. The amount of P adsorbed increased with increasing ionic strength. The amount of P adsorbed increased continuously as pH values increased from 3 to 9 for P adsorption at 10 mg/L. Other series of P concentrations in solution showed variable trends due to the rates of P adsorption being affected by pH associated with the effect of ionic strength. The maximum amounts of P adsorbed and the highest percentages of P adsorbed were obtained at pH 9 for all levels of P concentrations, and at pH 7 for the lower P concentrations in solution. Calcium (Ca) ion was found to form a bridge for P adsorption in solution as the increases in the amount of P adsorbed at high pH values, which was related to the performance of Ca in favoring P to be adsorbed either onto the surfaces or incorporated into the structural bonds of MCMWM. Ionic strength, pH and modification process have been found to be the important factors that influenced P adsorption in solution.