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THE EFFECT OF PH, PHOSPHATE AND OXIDANT TYPE ON THE REMOVAL OF ARSENIC FROM DRINKING WATER DURING IRON REMOVAL
Citation:
Lytle*, D A., C M. Frietch*, AND T J. Sorg*. THE EFFECT OF PH, PHOSPHATE AND OXIDANT TYPE ON THE REMOVAL OF ARSENIC FROM DRINKING WATER DURING IRON REMOVAL. Presented at AWWA WQTC, Philadelphia, PA, March 14 - November 01, 2003.
Impact/Purpose:
To inform the public
Description:
In many regions of the United States, groundwaters that contain arsenic (primarily As[III]) also contain significant amounts of iron (Fe[II]). Arsenic removal will most likely be achieved by iron removal in many of those cases which will consist of oxidization followed by filtration. As(V) adsorbs to the resulting Fe(III) (hydr)oxide particles that form which are filtered from the water. Water chemistry and the manner in which the oxidation step(s) is practiced can influence arsenic removal. For example, pH affects the degree of arsenic adsorption by controlling the arsenic and iron particle surface charges, and anions such as phosphate, silicate and sulfate compete for adsorption sites. Although this is known, the degree of interference to be expected for a range of pH and anion concentrations is not well defined for the broad range of waters in the United States. The type of oxidant (s) used to oxidize arsenic and iron, and in some cases the addition sequence of multiple oxidant systems can also affect arsenic removal effectiveness although not well known. Important particle properties such as surface area can be affected by the type of oxidant used which can affect arsenic removal.