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The Kinetics of Fe(II) Oxidation and Well Screen Encrustation
Author(s) -
Applin Kenneth R.,
Zhao Naiyu
Publication year - 1989
Publication title -
groundwater
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.84
H-Index - 94
eISSN - 1745-6584
pISSN - 0017-467X
DOI - 10.1111/j.1745-6584.1989.tb00437.x
Subject(s) - ferrous , dispersion (optics) , ferric , aquifer , groundwater , chemistry , oxygen , kinetics , environmental chemistry , inorganic chemistry , geology , geotechnical engineering , physics , quantum mechanics , organic chemistry , optics
The unconsolidatcd sediments which border the Missouri River constitute an important ground‐water aquifer that has been developed for municipal and industrial water supplies. The hydraulic efficiency of wells in these sediments decreases with time because of well screen encrustation caused by the oxidation of dissolved ferrous iron to insoluble ferric oxyhydroxides. The kinetics of ferrous iron oxidation are strongly dependent upon the solution pH and to a lesser extent the dissolved oxygen content. Chemical analyses of the well water including pH, Eh, dissolved oxygen, and dissolved iron indicate that at least one‐half time for ferrous iron oxidation occurs prior to ground water entering the wells. As ground‐water velocity increases near a pumping well, shallow, oxygen‐bearing ground water may mix with deeper, reduced water by mechanical dispersion and turbulent flow and facilitate the oxidation of dissolved ferrous iron. Although little can be done to prevent well screen encrustation, the rate of encrustation may be slowed by regulated pumping and avoidance of shutdowns.