AWWA JAW59700

This two-phase study investigated iron (Fe) coagulation followed directly by microfiltration (CMF) as a treatment for removing arsenic (As) from groundwater in Albuquerque, N.M. In the first phase, bench-scale tests were conducted to determine the effect of As oxidation state, pH, Fe dose, silica concentration, mixing time, and filter pore size on As removal. The second phase consisted of a pilot study to investigate such variables as pH, Fe dose, mixing time and energy, filtrate flux, and backwash interval. The most important variables controlling As removal were pH and Fe dose. As removals to <2 ¿¿g/L were achieved using either a 7 mg/L Fe dose without deliberate pH reduction or a smaller dose of 1.9 mg/L Fe after addition of sulfuric acid to reduce pH to 6.4. Continuous three- to five-day operation of the CMF pilot-scale process verified efficient filter performance and showed no increase in transmembrane pressure, even after five days. CMF represents an innovative treatment technology for removing arsenic (As) from groundwater. By eliminating the flocculation step, the process offers water providers savings in both space and cost. Designed to be compact, CMF is especially useful for smaller systems or larger systems where space is a constraint. Includes 25 references, table, figures.