Evaluation of Factors Affecting Performance of Direct Filtration

Abstract

The effects of selected initial conditions and operating parameters on the direct filtration process are evaluated by using a synthetic water/benchscale apparatus. An orthogonal design of the controlled experimental conditions was used so that the contribution of each controlled variable could be distinguished. The effects of the specific alum doses selected for evaluation on process performance were much greater than the effects of initial water quality conditions or operational/pretreatment parameters. It was found that, when operating near the optimum regions of charge neutralization or aluminum hydroxide precipitation removal mechanisms, the influence of the variables examined was significantly reduced. The results also suggest the existence of a fraction of aquatic organic matter in raw water sources which is not amenable to removal by direct filtration using alum coagulation.