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Subsurface or in-situ iron removal involves the injection of aerated water into an anaerobicaquifer. Processes of adsorption, oxidation and precipitation result in reduced ironconcentrations in the abstracted water. However, subsurface treatment has also an effect onarsenic and phosphate levels in the groundwater. Arsenic, phosphate and iron show a similarpattern during an injection-abstraction cycle. Once injection is stopped for a longer period,iron and arsenic concentrations increase significantly, the occurrence of arsenicremobilization is, however, not certain. The enhanced nitrification on the dry biofilters aftersubsurface treatment has been observed as another beneficial side effect. In this studyammonia oxidizing bacteria (AOB) and archaea (AOA), and G. ferruginea were identified tobe present at higher levels in the subsurface aerated water than in reference (i.e., backgound)groundwater especially at the beginning of the abstraction period. G. ferruginea couldinfluence iron oxidation and removal in biofilters in a similar way as was previouslyhypothesized for iron colloids. Includes 23 references, table, figures.

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Edition: Vol. - No. Published: 11/01/2008 Number of Pages: 12File Size: 1 file , 1 MB