AWWA ACE58127

One of the important aspects of implementation of microfiltration (MF)/ultrafiltration (UF) membranes, either for a new plant or for retrofitting them into an existing plant, is the pretreatment requirement. It is generally accepted that for low turbidity waters and, if removal of dissolved materials is not required, MF/UF membranes could be used for filtration of source water with minimal pretreatment such as a prescreen. For source water characterized by high turbidity, pretreatment is typically desirable as it improves the performance of the MF/UF membranes thereby reducing the life cycle costs. The pretreatment for such water could be coagulation with or without sedimentation depending on the water quality. However, for water quality characterized by moderate turbidity, few studies are available to help determine whether the improvement in the performance of the membranes with pretreatment would justify the cost of pretreatment. This paper addresses this issue and one utility's experience in determining the cost-effective approach in increasing the capacity of an existing plant and improving the water quality using MF/UF membrane filtration. Includes tables, figures.