Papers by Keyword: Acid Mine Drainage

Abstract: Acid mine drainage (AMD) presents numerous problems to the aquatic life and surrounding ecosystems. However, little is known about the geographic distribution, diversity, composition, structure and function of AMD microbial communities. In this study, an AMD-specific microarray was used to analyze nine AMD microbial communities, and showed that those nine AMD microbial communities had high variations measured by the number of detected genes, overlapping genes between samples, unique genes, and diversity indices. Statistical analyses indicated that the concentrations of Fe, S, Ca, Mg, Zn, Cu and pH had strong impacts on both phylogenetic and functional diversity, composition, and structure of AMD microbial communities. This study provides insights into our understanding of the geographic distribution, diversity, composition, structure and functional potential of AMD microbial communities and key environmental factors shaping them.

Abstract: Heavy metals, e.g. copper and nickel, are released to the environment as a result of mining activities. Heavy metals are required by most living organisms as trace elements, but in excess they are toxic and cause considerable environmental stress. Microbes have developed different strategies to tolerate otherwise toxic conditions. In the surroundings of closed Kotalahti Mine the concentrations of copper and nickel in the water have earlier been highly elevated. In order to decrease the concentrations of heavy metals and increase water pH, manure sludge was added to the flooded mine pit. This in situ bioreactor has operated successfully for 15 years after the treatment. The current concentrations of heavy metals are generally low. Nevertheless, resistance genes for copper (copA), cadmium-nickel (cnrA), nickel-cadmium-cobalt (nccA) and cadmium-zink (czcA) could still be found in the microbial community of the flooding water.

Abstract: Although acidophilic iron oxidizing bacteria related to “Ferrovum myxofaciens” P3G have been detected in various mining sites the knowledge about their physiology is limited to the type strain “F. myxofaciens” P3G. In order to further the knowledge on the metabolic capacity of “Ferrovum” related iron oxidizers we conducted a comparative genome analysis of three “Ferrovum” strains: JA12, PN-J185 and Z-31 (Z-31). The results of the phylogenetic analysis and the genome-to-genome distance calculation indicate that Z-31 belongs to a different “Ferrovum” species than JA12 and PN-J185. Comparative genome analyses revealed variations regarding the carbon, nitrogen and energy metabolism of the three strains which also corroborate the results concerning their phylogenetic relationship.

Abstract: In Central Chile, acid mine drainages (AMDs) are characterized by high concentrations of copper, which can be recovered. Passive biochemical reactors are eco-friendly technologies for the treatment of AMD. They use organic substrate mixtures to drive microbial sulfate reduction and metal sulfide precipitate formation. The performance of conventional biochemical reactors, however, is limited by metal toxicity, and metal recovery is difficult. Diffusive exchange systems on the other hand can be tailored to resist metal toxicity. This is achieved by having separate zones for AMD movement and for sulfate reduction, and by allowing the diffusive exchange of solutes between these zones. Also, higher reaction rates are possible, because much finer organic materials can be utilized as substrates. A key innovation of this research is the use of vertical tubular screens to convey the AMD through the reactor while simultaneously allowing transverse diffusive exchange of dissolved species with the substrate. The tubular screens act as reactors for precipitate formation, settling and accumulation, from where precipitates can be periodically recovered. This design promotes higher reaction rates, eliminates clogging and facilitates the recovery of valuable metals. This work studied the performance of a 2-m long vertical diffusive exchange column. Detailed insight was gained into reactions and transport processes within the tubular screen by the use of several sampling points along the column. During the first two months the reactor was fed with increasing concentrations of sulfate only, to determine its sulfate reduction potential. Then the reactor was fed with AMD for three additional months. During the operation with AMD, significant metal removal occurred, and copper precipitates accumulated, and were recovered.

Abstract: Acid mine drainage contains many toxic pollutants, mainly heavy metals and sulphates, which have negative impact on the environment. This paper deal with a study of two precipitates from acid mine drainage outflowing from the abandoned mine Smolnik (Slovakia). The precipitates were created after defrosting of mine water and after the process of oxidation. After drying the precipitates were analysed by infrared spectrometry and scanning electron microscopy (SEM) with EDX analysis. Using infrared spectrometry it was found that the precipitate contained OH^-, SO₄^2- functional groups. The inhomogeneous structure of the precipitate was observed by SEM with EDX analysis. The presence of CaSO₄.2H₂O (approx. 90 %) in precipitate after defrosting was confirmed by FTIR and SEM with EDX. Particulate substances after oxidation consisted mainly iron (30.5%), oxygen (44.4 %) and sulphur (7.9 %). Complex compounds with mainly contents of iron (III), hydroxides and sulphate with crystal bound water in structure were identified.

Abstract: In this study, two different bed materials in media filter systems were examined. Natural zeolite has the ability to take up heavy metals (Cd, Zn) from acid mine drainage (AMD) as well as zero-valent iron (ZVI). The aim of the study was to estimate the ability to remove heavy metals of Natural zeolite and compare the efficiencies of the two media. A major purpose of this report was to determine which media would have a higher permeation rate after running a period of time. It was concluded that ZVI had a higher efficiency of taking up heavy metals (>96.5%) and a faster permeation rate which had a longer operating life.

Abstract: Three polyvinyl chloride (PVC) columns filled with different ratios of reactive media, ceramsite and corncob, were conducted to assess the treatment performance of simulated acid mine drainage (AMD). The results indicated that the columns could effectively remove sulfate and metal ions from AMD with the removal efficiency of 57.7% and 96.5% respectively. The removal efficiency decreased with the increasing inlet velocity and at the same sample ports the sulfate and metal ions concentrations at the velocity of 1 ml/min were lower than that at the velocity of 2ml/min and 3ml/min.

Abstract: Abstract. Pan de Azúcar abandoned mine is located in Jujuy province, Argentina. The impact of that pollution was evaluated determining the density and the composition of the vegetation around the tailings. Also soil and plants samples were collected and their metal contents were determined. Deyeuxia breviaristata was the main native plant in the most polluted soils and its biomass had the highest concentration of zinc and lead. Acid mine drainage (AMD) samples were collected and their toxic effects were analyzed by ecotoxicology assays employed Lactuca sativa L. seeds; CI50₁₂₀ of 0.03 % v/v was determined. From mineral and AMD samples some iron- and sulphur-oxidizing microorganisms were isolated and also characterised by molecular techniques. AMD potential was evaluated for different tailing samples inoculating native microorganisms; deeper samples produced drainage with pH close to 1 and released iron above of 1000 ppm. AMD can reach Cincel River which is the main tributary of Laguna Pozuelos (just 25 km from the mine). Laguna Pozuelos is a Natural Monument, Biosphere Reserve and Ramsar site.

Abstract: Here we describe the potential uptake and assimilation pathways for the essential nutrients C, N, P, and S in the acidophilic iron oxidiser Ferrovum strain JA12, a member of a novel genus among the Betaproteobacteria. Comparative genomics proved to be a powerful approach to give first insights into the biochemical potential of this novel genus and to understand the reasons for the dominating abundance of Ferrovum spp. in a pilot plant to remediate acid mine drainage.

Abstract: Treatment of acidic Fe (II)- and sulfate-rich mine waters represents a major problem in many areas of the world. Therefore, a process was developed which utilises naturally occurring sulfate-reducing microorganisms for the elimination of sulfate and of part of the acidity from the acidic mine water. In order to improve the performance of this biological sulfate reduction process an in-depth analysis of the microbial diversity and activity in dependence of the hydraulic retention time (HRT) and other process parameters used to run the bioreactors was undertaken. This comparison demonstrated a positive correlation between shorter HRT and increasing sulfate reduction rates. The improvement in performance with decreasing HRT was paralleled by an increase of the total enzymatic activity (measured as hydrolase activity) of the microbial community and of the biomass (measured as protein concentration) in the bioreactors. A partial taxonomic identification of the microbial community in the bioreactors was achieved via nucleotide sequence analysis of a clone library of PCR-amplified 16S rRNA gene fragments prepared from a sample of the microbial biofilm in the bioreactor. Additionally, the genetic fingerprint technique T-RFLP was used to assess temporal changes of the microbial community in the biofilm within the reactor.