Illite for the removal of E. coli by filtration in water treatment processes: A comparative study

Abstract

The use of illite for the removal of microorganisms from water has not been studied by other researchers. We assessed the applicability of illite for bacterial removal from water and compared it with commercially available filter media. Column experiments were performed to evaluate the bacterial removal efficiency of filter media under different pH conditions and with chlorine-free tap water. The removal percentage of illite was higher than 90% and its sticking efficiency was greater than 0.85 under all experimental conditions. The removal percentage and sticking efficiency of illite were far superior to that of the other filter media. The high bacterial removal efficiency of illite may be a result of bacterial adhesion enhancement by the Al and Fe eluted from illite. A response surface methodology was employed to optimize experimental conditions including pH, filter depth, and flow rate and to elucidate the effects and interactions of these variables. All these parameters significantly influenced the bacterial removal of illite. From the optimization study, the highest removal percentage of 99.9% was obtained under conditions of a pH of 4.02, a filter depth of 18.49 cm, and a flow rate of 0.86 mL/min. Illite is a potential filter medium for purifying water and preventing groundwater pollution from septic tanks and carcass disposal.