AWWA MTC57597

In response to extended drought conditions and shrinking source water supply, the City of Wichita Falls has begun a capital improvements program to build a new dual-stage membrane (microfiltration and reverse osmosis) water treatment plant necessary to develop an existing surface water supply that was historically considered unfit as a public water supply. The use of membranes is expanding towards the treatment of more complex source waters featuring high levels of dissolved contaminants (DOC, color, taste and odor causing substances) and high levels of particulate material (turbidity, microorganisms, suspended solids). When membranes are considered for these more difficult to treat waters, the choice of direct filtration must be evaluated against integration of a preclarification unit process. This paper presents the pilot evaluation process and data used to select a pretreatment approach used to design the new 10 MGD dual stage membrane surface water plant for the City of Wichita Falls, Texas. The performance of the membrane pilot system is discussed for both scenarios: in direct dosing/filtration and in preclarification. Design of the core system equipment and calculation tools developed during the design of the system is also presented. Includes tables, figures.