AWWA JAW65357

This research was undertaken to evaluate the feasibility and cost-effectiveness of granular ferric hydroxide (GFH) for arsenic removal, in response to the 2002 US Environmental Protection Agency (USEPA) lowering of the arsenic maximum contaminant level to 10 µg/L in drinking water. The research modeled the adsorption activation energy, kinetics, and isotherm thermodynamic parameters. Results show GFH to be a promising and cost-effective arsenic(V), or As(V), sorbent. GFH adsorbs As(V) readily and has a large As(V) adsorption capacity indicated by kinetics and isotherm models. The adsorption is nonlinear, heterogeneous, and multilayered. It can also be compromised by the presence of competitive anions, such as silica, vanadium, selenium, and phosphate in natural waters. The interference of silica, for example, may require a pretreatment step to prolong the life of GFH as an arsenic sorbent. This could be achieved through the commonly used unit process of coagulation/flocculation. The thermodynamics parameters established for GFH As(V) removal will help water utility managers compare and find the most suitable arsenic removal strategy to meet the needs of their utilities. Includes 33 references, tables, figures.