AWWA MTC57650

Increasing water demands and more stringent US Environmental Protection Agency (EPA) regulations prompted Upper Trinity Regional Water District (UTRWD) north of Dallas, Texas to pursue membrane technology for an upcoming district expansion. State regulatory guidelines require testing at the pilot scale level before state approval of a membrane process and maximum design operating flux (i.e., plant capacity). Such requirements become obvious when considering the wide variability in water quality for surface waters; each source has its own peculiarities. Fluctuations in raw water quality not only pose a threat to the potential breakdown in the treatment process, but require operator input to react to changing conditions. The ability to automate and remotely control/operate membrane processes was one of the motivations behind consideration of membrane technology. Seasonal and daily fluctuations observed in this study included: taste and odor compounds, turbidity, total organic carbon (TOC), temperature, and Fe/Mn concentrations. Raw water quality fluctuations ranged from moderate (65% increase in average total organic carbon) to excessive (292% increase in average turbidity). Pretreatment with ferric sulfate coagulation was immediately followed by membrane filtration. Three membrane units, Hydranautics, Pall Corporation, and Zenon Environmental were tested from September 2001 to April 2002. With optimized coagulant dose, flux, and backwash parameters, membrane filtration was shown to be a viable option. Initial plant size for the fullscale installation will be 11-mgd, expandable to 30-mgd in 10 years. Includes 6 references, tables, figures.