AWWA WQTC57136

"Red water" describes the appearance of drinking water that contains suspended particulateiron although the actual suspension color may be light yellow to brown depending on waterchemistry and particle properties. Iron can originate from the source water and from distributionsystem materials. The relatively soluble +II oxidation state is the dominant form of iron in anoxicenvironments including some groundwaters, the hypolimnion of eutrophic reservoirs, drinking waterdistribution system dead ends, and beneath thick iron corrosion scales. Upon exposure to oxygenor disinfectant during water treatment and distribution, Fe(II) is oxidized to the insoluble Fe(III)form, which readily precipitates and is responsible for colored water. The oxidation of Fe(II) is the basis for iron removal treatment of iron-containinggroundwaters, and an important step in iron corrosion byproduct development and red waterformation in drinking water distribution systems. The relationships between redox potential, andaqueous iron chemistry and iron mineralogy are well known. No research, however, has consideredthe effect of oxidant type on the properties of Fe[III] particle suspensions formed following theoxidation of Fe[II]. The objective of this research was to study the effect of oxidant (oxygen and free chlorine)on the properties of iron particles and suspensions formed from the oxidation of Fe[II] over a broadpH range. Particle properties including size, electrophoretic mobility, and suspension propertiesincluding turbidity and color were studied. Iron particle suspensions formed following the oxidation of Fe(II) by oxygen and freechlorine have dramatically different color and turbidity properties independent of pH. Suspensionproperty differences indicated that differences in the iron particles existed. The particle propertiesexamined in this investigation (size, zeta potential and crystalline nature), however, did not shownotable differences in particles formed in oxygen and chlorine systems. Additional particle analysisincluding density measurements and particle image analysis will be performed to identify particledifferences. Includes 3 references, figures.

Product Details

Edition:

Vol. - No.

Published:

11/01/2002

Number of Pages:

8

File Size:

1 file , 280 KB