Bench-Scale Evaluation of Alternative Cr(VI) Removal Options for Small Systems


This webcast will discuss the findings of the recently published report, Bench-Scale Evaluation of Alternative Cr(VI) Removal Options for Small Systems (#4561). This project guides utilities that need to treat water containing greater than 10 µg/L hexavalent chromium at a flow of 2 million gallons per day (MGD) or less. This guidance includes the effect of various water quality parameters such as sulfate, nitrate, and arsenic concentrations on treatment efficacy, preliminary site layouts for the most appropriate treatment scheme, and high-level budgetary cost opinions on the selected treatment scheme.

Four ion exchange media, including two SBA (strong base anion) media and two WBA (weak base anion) media, and two iron-based media were evaluated as part of this study. The performance of each media type was assessed in water supplied by five participating utilities that represented a range of concentrations of various water quality parameters. The media performance was also evaluated when competing solutes were present. These included sulfate, nitrate, chloride, silicon, alkalinity, and natural organic matter. Three media were selected for further testing in small-scale columns.

Results from the bench-scale study and the column tests were used to develop practical guidance for selecting a treatment technology for smaller systems. The practical guidance includes process descriptions, process flow diagrams, residuals disposal considerations, typical footprint information and concept-level cost opinions. The guidance developed in this study can be directly applied by systems that are addressing hexavalent chromium in their water supplies. The results of this study would be of interest to water utility professionals, consultants and academic members.