AWWA WKICO66057

This paper presents results of an on-going study exploring the treatment of membrane concentrate through addition of ferric iron solids followed by solid-liquid separation. Arsenic was measured using flow injection ICP-MS; standard matrices were matched to the samples to minimize chloride interference. Arsenic removal by adsorption to pre-formed hydrous ferric oxide as compared to in situ precipitation of ferric chloride is discussed. Experimental findings are compared to pseudo-steady-state PHREEQC model predictions using reaction constants provided in the literature. The model simulated arsenic removal by adsorption to pre-formed solids quite well; however, the specific concentration of surface functional groups (moles sites/mole Fe) was increased to predict arsenic removal for in situ precipitation. Potential reasons for this difference are addressed. Includes 8 references, tables, figures.