AWWA MTC69736

The membrane suppliers have produced low-pressure membranes that are applied in current treatment process schemes to enhance the water quality effluent required to meet additional regulatory guidelines. Treatment process designers today are likely to combine membranes with pretreatment technologies to address a broad range of water quality problems including dissolved contaminants, color, organics, or taste and odor. In addition to expanding plant treatment capabilities, these pretreatment processes have been found to optimize membrane performance and reduce capital and whole-life costs. The benefit of providing a Dissolved Air Flotation System for low-pressure membrane pretreatment is to remove raw water contaminants so that the plant can increase the membrane flux rate (up to as high as state allowable), reduce membrane cleanings, and prolong the membrane life. Dissolved air flotation system technology is presented along with pilot data collected at the Lopez Plant of the San Luis Obispo Water Utility. The pilot performance supported the benefits of membrane pretreatment and showed total cost savings in both capital and operating expenses. Actual plant performance data with respect to water quality and unit operations of both the dissolved air flotation and the low pressure membranes is also presented. These new systems began operations at the plant in May 2007. Includes tables, figures.