Dissolved selenium species in the +VI (selenate) and +IV (selenite) oxidation states that are toxic to humans and aquatic organisms can be produced from various industrial activities. Iron electrocoagulation is a promising approach for removing these selenium species from water. By regulating the oxygen level and pH, electrocoagulation generates diverse types of Fe(II)- and Fe(III)- containing solids that can affect the rate and extent of dissolved selenium removal. The objective of this study was to examine the impacts of pH and dissolved oxygen concentration on the performance of iron electrocoagulation for Se(VI) removal. Our results show that at pH 8, Se(VI) removal was more efficient at lower oxygen levels, mainly due to production of solid phase Fe(II) in the form of ferrous hydroxide and green rust. On the other hand, at pH 6, Se(VI) removal was not substantially influenced by oxygen level. The iron electrocoagulation process was found to be more effective than simple addition of dissolved Fe(II) or reaction with preformed Fe(II)-containing solids. Control experiments show that dissolved Se removal by iron electrocoagulation is more effective than by chemical addition of comparable amounts of Fe(II).

Iron electrocoagulation for removal of dissolved selenium: Impact of oxygen level and pH

253rd National Meeting (2017)

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