AWWA WQTC69406

Arizona is a state known for warmth. High temperatures, coupled with Arizona's dry climate require that municipalities in Arizona produce waters from unusual sources. An example is the City of Goodyear (City), Arizona's Well 12B facility where arsenic, fluoride and Total Dissolved Solids (TDS) make untreated groundwater undrinkable. Additionally, the ambient groundwater temperature ranges from 103F to 107F pushing the temperature limits of a polymeric membrane system. Operation of a conventional reverse osmosis (RO) system under these conditions is uncommon; a high performance membrane is required because of decreased salt rejection caused by the elevated temperature. Additional treatment challenges include low levels of calcium in the groundwater coupled with high fluoride levels, which limit RO treatment bypass blending and place additional constraints on product water stabilization. By comparison, the City uses similar RO membranes for salt and nitrate removal at the Bullard Water Campus where the ambient groundwater temperature ranges from 77F to 80F. Although the operating range at Well 12B is within the capabilities of most RO projection software, there are not a lot of municipal systems that use RO to treat water at these temperature conditions and comparison of projected values to achievable values is limited. This paper presents and compares operational data from both facilities to illustrate the differences in performance of a common high rejection brackish water membrane under considerably different temperature conditions. Includes 5 references, tables, figures.