Evolution of Geochemical and Mineralogical Parameters during In Situ Remediation of a Marine Shore Tailings Deposit by the Implementation of a Wetland Cover

Abstract

We present data of the time-evolution of a remediation approach on a marine shore tailings deposit by the implementation of an artificial wetland. Two remediation cells were constructed: one in the northern area at sea-level and one in the central delta area (above sea-level) of the tailings. At the beginning, the "sea-level" remediation cell had a low pH (3.1), with high concentrations of dissolved metals and sulfate and chloride ions and showed sandy grain size. After wetland implementation, the "sea-level" remediation cell was rapidly water-saturated, the acidity was consumed, and after four months the efficiency of metal removal from solution was up to 79.5%-99.4% for Fe, 94.6%-99.9% for Mn, and 96.1%-99.6% for Zn. Al and Cu concentrations decreased below detection limit. The "above sea-level" remediation cell was characterized by the same pH (3.1) and finer grain size (clayey-silty), and with some lower element concentrations than in the "sea-level" cell. Even after one year of flooding, the "above sea-level" cell was not completely flooded, showing on-going sulfide oxidation in between the wetland cover and the groundwater level; the pH increased only to 4.4 and metal concentrations decreased only by 96% for Fe, 88% for Al, 51% for Cu, 97% for Mn, and 95% for Zn. During a dry period, the water level dropped in the "sea-level" cell, resulting in a seawater ingression, which triggered the desorption of As into solution. These data show that the applied OPEN ACCESSMinerals 2014, 4 579 remediation approach for this tailings deposit is successful, if the system is maintained water-saturated. Metal removal from solution was possible in both systems: first, as a result of sorption on Fe(III) hydroxide/and/or clay minerals and/or co-precipitation processes after rise of pH; and then, with more reducing conditions, due to metal sulfides precipitation.

Temporal evolution of bacterial communities associated with the in situ wetland-based remediation of a marine shore porphyry copper tailings deposit

“…As a passive system, constructed wetlands are particularly attractive due to low operating cost (Mayes et al, 2009) and are now a technology with potential success when deep reducing conditions are attained (Sheoran and Sheoran, 2006;Ňancucheo and Johnson, 2012). Constructed wetlands have been successfully applied to some mining environments to remove contaminants from water, especially from metal-rich effluents (Diaby and Dold, 2014). The geochemical processes involved in this technique are based on sulfur and sulfate reduction activities, mediated or accelerated by a heterotrophic microbial community fueled with organic carbon produced by the aquatic plants growing in the wetland.…”

“…For this study, a remediation cell (ca. 30 by 30 m) was constructed on a remaining oxidized section of the tailings (Diaby, 2009;Diaby and Dold, 2014). Chemical analysis and a comprehensive survey of the microbial community present in the tailings were conducted over a period of nine months, starting at the beginning of the flooding (Diaby and Dold, 2014).…”

Evolution of Acid Mine Drainage Formation in Sulphidic Mine Tailings

“…This is the final stage of AMD formation and the patient is now extremely ill (you can see it clearly in his green, yellow, blue face), where only final long-term treatment might mitigate the environmental damage. Prevention is here not possible any more, in some cases some drastic remediation with complete saturation of the system might help to alive the symptoms, if there is enough suitable water available [41,66] and the dam stability is not an issue.…”

Submarine Tailings Disposal (STD)—A Review

“…The difference from Chañaral is that here enough water was available to start a successful remediation [10,88]. Also, the tailings in the Locumba River valley were removed by a clean-up initiated by Southern Peru Copper Corporation.…”