Microcosm Studies for Neutralization of Hypolimnic Acid Mine Pit Lake Water (pH 2.6)

Abstract

Ten microcosms of 0.088 m3 water volume (0.3 m i.d. and 1.20 m height) were designed for neutralization studies representing hypolimnic ecosystem models for acid mine pit lakes. Sediment and water were collected from an acid lignite mine pit lake (Brandenburg, Germany) and filled into the microcosms. To determine the efficacy of controlled in situ organic carbon amendments as a possible neutralization method, sediment and water were treated with ethanol and Carbokalk with and without wheat straw. The water chemistry was monitored for 1 yr. At start-up and end of the experiments, the sedimentwas characterized. Iron and sulfate were removed with varying intensity from the water phase as a result of microbial iron and sulfate reduction together with a subsequent precipitation of unsoluble sulfide minerals to the sediment. The pH rose, and alkalinity generation and bacterial growth were observed. Neutralization rates were calculated using equivalents of accumulated total reduced inorganic sulfur together with the nonsulfidic reactive ferrous iron in the sediment. In the treated microcosms, the neutralization rates were between 6 and 15 equiv m(-2) a(-1). Carbokalk was most effective in stimulating growth of sulfate-reducing bacteria and probably also served as inoculum. With Carbokalk together with wheat straw, the pH increased from 2.6 to around 6.5 within the whole microcosm. The critical revision of the results indicates that the application of Carbokalk (approximately 3.9 kg m(-2)) together with the application of wheat straw (approximately 9.3 kg m(-2)) is most suitable for further experiments in outdoor enclosures (mesocosms). For that case, the prediction of the water quality for a lake water column after multiple lake turnover events is presented based on batch reaction simulation using the geochemical model PHREEQC.

Microcosm Testing of Municipal Sewage and Green Waste for Full-Scale Remediation of an Acid Coal Pit Lake, in Semi-Arid Tropical Australia

“…Firstly, most other research published to date has occurred in cool temperate areas of Europe and North America e.g., (Benner et al, 2002;Frömmichen et al, 2004;Küsel and Dorsch, 2000;Küsel et al, 2001;Tostche et al, 2003). The higher temperatures experienced in Collinsville, even during the middle of the Dry season (19.5-28.2 o C) are likely to have exponentially increased biochemical rates of carbon diagenesis and metabolism.…”

“…Secondly, the use of largely fresh green waste as opposed to refractory organic substrates such as straw (Frömmichen et al, 2003;Frömmichen et al, 2004), rye grass (Harris and Ragusa, 2000;Harris and Ragusa, 2001), etc., distinguishes this research from many others in the published literature. The greater labile fraction of organic material available in this fresher material may have contributed directly to electron donors for SO 4 -2 reduction.…”

“…Hard et al (2003) echoed this view noting that, "For a microbial process to be economically feasible, the carbon (C) and energy source should be cheap, widely available and highly effective." However, most experiments into the utility of SO 4 -2 reduction processes for ameliorating AMD have instead focused upon highly labile but expensive C substrates such as ethanol (Kolmert and Johnson, 2001;Martin et al, 2003;McNee et al, 2003), sugar (Frömmichen et al, 2003;Frömmichen et al, 2004;Geller et al, 2003;Pöhler et al, 2002;Wendt-Potthoff et al, 2002), cow manure (Drury, 1999;Drury, 2000), etc. For many remote mining locations, these materials are unviable for practical and economic reasons.…”

“…However, since Tuttle et al (1969) first suggested the use of SO 4 2-reducing bacteria (SRB) in the treatment of AMD, treatment has largely focused on ex-situ treatment in bioreactors. What in-situ treatment relevant experiments have occurred have generally been performed at microcosm (e.g., carboy vessels; (Castro et al, 1999;Frömmichen et al, 2004;Fyson et al, 1998)) or at best macrocosm (e.g., limnocorrals) scales (Martin et al, 2003). It is largely recently that attention has switched to insitu remediation systems at actual field treatment scales (Gibert et al, 2002).…”

Influence of mine drainage on water quality along River Nyaba in Enugu South-Eastern Nigeria

“…Some documented cases include that of Kimmel (1983), Alpers and Blowes (1994), Nordstrom and Alpers (1999), Frommichen et al (2004), Geldenhaus and Ball (1998), Jenkins et al (2000), Bachmann et al (2001), Fontbole (2001), Holmstrom et al (2001), USGS, USEPA (2002), D.E.P (2002), Ehrlich (2004), Denimal et al (2005), Ata and Kodas (2006) and Egiebor and Oni (2007). In the study area, at the end of the mining activities in 2004, the mine was left un-reclaimed; water bodies collected in them forming perennial mine ponds.…”