Characterization of Iron and Manganese Precipitates from an In Situ Ground Water Treatment Plant

Abstract

Aquifer samples from the precipitation zone of an in situ iron and manganese removal plant that was operated for 10 years were analyzed for iron and manganese minerals. Measurements were performed by various chemical extraction techniques (5 M HCI, 0.008 M Ti(III)-EDTA, 0.114 M ascorbic acid), X-ray diffraction and Mössbauer spectroscopy. Chemical extractions showed that iron was precipitated as ferric oxides, whereas manganese was not oxidized but deposited as Mn(II) probably within carbonates. The ferric oxides in particular accumulate preferentially in the smaller grain- size fractions. This tendency was observed to a lesser extent for manganese. X-ray diffraction and Mössbauer spectroscopy showed that the ferric oxides were mainly crystalline (goethite, 50% to 100% of the iron). Ferrihydrite was found as well, but only as a minor fraction (< or = 12%). Pure manganese minerals were not found by X-ray diffraction. The precipitated amounts of iron (5 to 27 micromol/g Fe as ferric oxide) and manganese (1 to 4 micromol/g Mn) during 10 years operation of the treatment plant agree with values that were estimated from operational parameters (9 to 31 micromol/g Fe and 3 to 6 micromol/g Mn). Considering the small amounts of precipitated iron and manganese, no long-term risks of clogging of the aquifer are expected.

Sorption and catalytic oxidation of Fe(II) at the surface of calcite

“…It was shown previously, that in-situ removal of iron occurs via surface adsorption, surface oxidation of Fe(II) and precipitation of Fe oxides ). This mechanism was found to be responsible for Fe(II) removal at an in-situ treatment plant in a calcareous aquifer in north western Switzerland (Mettler and von Gunten (2001), Teutsch et al (2005)). The present study aims at investigating quantitatively the mechanisms of Fe(II) surface adsorption, precipitation and oxidation in calcite systems.…”

“…Alternatively, Fe(II) removal is often carried out via microbiologically mediated processes (Rundell and Randtke (1987), Mouchet (1992), Benz et al (1998), Søgaard et al (2001), Emerson and Weiss (2004)). In-situ ferrous iron removal techniques involve injection of aerated water and the precipitation of Fe oxides (actually, oxyhydroxides and oxides) within the aquifer (Hallberg andMartinell (1976), van Beek (1985), Seyfried and Olthoff (1985), Rott and Meyerhoff (1994), Mettler and von Gunten (2001), Teutsch et al (2005)). It was shown previously, that in-situ removal of iron occurs via surface adsorption, surface oxidation of Fe(II) and precipitation of Fe oxides ).…”

Hydrogeochemical Assessment of Groundwater Quality Security in the Collection Conduit Area, Naeseong-Cheon

“…적인 산소수의 주입과 같은 현장 처리 기술이 개발되어 왔다 (Hallberg and Martinell, 1976;Rott and Lamberth, 1993;Appelo et al, 1999;Mettler et al, 2001;Kedziorek and Bourg, 2009). 1969년에 지중 철망간 처리 시설이 최초로 설치된 이후 산소수 주입 또는 공 기 접촉 등의 방식을 적용한 150개 이상의 플랜트가 10여개 국에서 설치 운영 중에 있다 (Braester and Martinell, 1988;Tredoux et al, 2004).…”

“…(Hallberg and Martinell, 1976;Diem and Stumm, 1984;Davies and Morgan, 1989;Seppanen, 1992;Mettler et al, 2001;Teutsch et al, 2005;Ahmad, 2012). 로 변하게 된다 (Maogong, 1988;Rott and Lamberth, 1993;Appelo et al, 1999;Araby et al, 2009;Halem et al, 2010;Halem et al, 2011 (Lovley, 1987;Lovely and Phillips, 1988;Cornell and Schwertmann, 1996).…”

Analysis of the Major Fe Bearing Mineral Phases in Recent Lake Sediments by EXAFS Spectroscopy

“…Dissolution and precipitation of iron minerals are controlled by redox conditions and different microbial and geochemical processes (Davison, 1993;Burdridge, 1993;Cornell and Schwertmann, 1996;Hansel et al, 2001;Mettler et al, 2001). There is a considerable Author for correspondence. interest to analyze the dominant mineral form of iron present in these environments.…”