Year-Round Performance of a Passive Sulfate-Reducing Bioreactor that Uses Rice Bran as an Organic Carbon Source to Treat Acid Mine Drainage

The development of compact and cost-effective passive treatment systems is of critical importance for acid mine drainage (AMD) remediation in Japan. The purpose of this study was to construct an AMD treatment system comprising a sulfate-reducing bioreactor using rice bran as a carbon source for sulfate-reducing bacteria (SRB) and to demonstrate its stable operation for at least a year in terms of continuous sulfate reduction and metal removal. Our 35 L bioreactor comprised a packed inoculum layer of a mixture of rice husks, limestone, and field soil, which was covered with rice bran. During operation, the AMD input flow rate was adjusted to 11.7 mL/min (hydraulic retention time, HRT; 50 h). Throughout the year, physicochemical analyses of system input and output AMD samples revealed that both pH and oxidation–reduction potential values were consistent with the process of sulfate reduction by SRB, although this reduction was observed to be stronger in summer than in winter. Efficient metal removal was observed, with concentrations at the outlet port of <0.33 mg/L Zn, <0.08 mg/L Cu, and <0.005 mg/L Cd, more than meeting Japan’s national effluent standards. Illumina sequencing of 16S rRNA genes revealed that Desulfatirhabdium butyrativorans-related species, which belong to a lineage within Deltaproteobacteria, were dominant (39–48% of the total SRB population) within the bioreactor.     

Accumulation of Arsenic and Copper by Bryophytes Growing in an Aquatic Environment near Copper Mine Tailings

Bryophytes with high As accumulation affinity were identified in the aquatic environment. We surveyed a stream near copper mine tailings and then conducted laboratory experiments to confirm As accumulation in the bryophytes with high As affinity. We found that a moss, Scopelophila cataractae, accumulates As in addition to Cu in aquatic environments and confirmed it in laboratory experiments. The highest value for As in S. cataractae from the field survey was 1300 mg/kg dry weight at relatively low As concentrations in the stream water (0.005 mg/L). In addition, Brachythecium plumosum and Rhynchostegium riparioides may also be useful bryophytes for accumulation of Cu and As, though the mechanisms of As accumulation might differ between these two bryophytes and S. cataractae.     

Unique Pit Lake Created in an Opencast Potassium Salt Mine (Dombrovska Pit Lake in Kalush,Ukraine)

We studied the physicochemical and biological characteristics of the Dombrovska pit lake in Ukraine. The lake formed in an abandoned opencast potassium salt mine and is one of the most saline inland water bodies in the world. It is 85 m deep (November 2015) and an annual inflow of about 2 Mm³ of water. The lake has two distinct layers. The mesohaline surface (0–5 m) layer is well oxygenated and slightly alkaline (pH?=?7.5–8.8). Its mineralization, expressed as dry mass, was 50–134 g dm^??3, and its electrical conductivity (EC) was 58–134 mS cm^??1. The underlying layer consists of hypersaline water with low amounts of dissolved oxygen, a neutral pH (6.7–7.4), high mineralization (179–420 g dm^??3), high EC (169–215 mS cm^??1), and higher concentrations of major anions and cations (except Ca²⁺) and nutrients than the overlying water. The vertical relationship between major ions and metals and the future salinity of the lake are discussed. In terms of zooplankton, in July we found living specimens of the rotifer Brachionus plicatilis and the ciliates Paradileptus elephantinus and Tindinnidium sp. as well as dead rotifers, cladocerans, and copepods (in total, 19 species), but only live B. plicatilis and 9 dead species in November. In the littoral part of the pit lake, we found the diatoms Nitzschia pusilla and some Halamphora species (H. borealis, H. tenerrima, H. acutiuscula), which favour highly saline waters.     

Rotifer Diversity in the Acidic Pyrite Mine Pit Lakes in the Sudety Mountains (Poland)

The diversity of rotifers was studied in three artificial water bodies (Azure Lake, Yellow Lake, and Purple Lake), which were once pyrite mines. The physicochemical parameters and the zooplankton composition of the water were determined. Azure Lake had a pH of 3.4–6.9, conductivity values of 165–194 µS cm^??1, and low concentrations of sulphate, calcium, magnesium, copper, and iron, while the other lakes had a pH of 2.6–2.9, a conductivity of 1636–3400 µS cm^??1, and high concentrations of sulphate (up to 2863 mg dm^??3), Cu (up to 2650 µg dm^??3), and Fe (up to 178.3 mg dm^??3). The rotifer community in the lakes comprised 27 taxa (15 in Azure Lake, 13 in Purple Lake and 14 in Yellow Lake). We also found two species that are rarely observed in Poland (Aspelta cincinator and Elosa spinifera), and three species commonly found in acidic water (E. worallii, Cephalodella delicata, and C. hoodi). The types of rotifers in Azure Lake differed from those in the other two lakes. The Shannon–Weaver biodiversity index (H′) was the highest in Purple Lake (H′?=?1.255) and lowest in Azure Lake (H′?=?0.455). The effect of some of the physicochemical parameters on rotifer diversity is discussed.     

Assessment of Rheological Properties of Bazhenov Formation by Thermobaric Test Data

The performed thermobaric tests of cylindrical bazhenite specimens consisted in recording of time variation in height of the specimens, h(t), under constant axial loading at varied temperature T. The authors demonstrate that under rapid increase/decrease in T deformation process obeys the thermoelastic law and calculate the coefficient of linear temperature expansion. Under constant increased temperature, the process of deformation is described using the viscoelastic Voigt model. The authors formulate and solve inverse problems on elastic moduli and viscosity of rocks by the data of h(t).     

Understanding Abiotic and Biotic Conditions in Post-Mining Pit Lakes for Efficient Management: A Case Study (Poland)

This study was aimed at determining whether the origin, morphometry, and hydrology of post-mining lakes affect their hydrochemical and hydrobiological parameters (i.e. water quality). The investigated post-mining lakes were very young compared to glacial lakes and represent early stages of ecosystem succession. Despite their different ages and morphometries, they are all mesotrophic and have good water quality. They have not been supplied with phosphorus and nitrogen, which can cause excessive development of pelagic phytoplankton; as a result, they share low chlorophyll a (Chl a) content, low phytoplankton biomass, and relatively high water transparency. Low abundance and species richness of zooplankton indicate low trophic levels in all of the lakes. Chl a in Lakes Przykona and Bogda?ów were within the range typical of mesotrophic lakes, while Lake Janiszew had very low Chl a, typical of an oligotrophic water body. The low N:P ratios (4–6), especially in summer, indicates nitrogen limitation of primary production. There is a risk that such a proportion of the major biogenic elements could lead to harmful cyanobacterial blooms. The lake basins were formed using quaternary deposits (sand, clay) at their bottoms; as a result, the lakes had a slightly alkaline pH (>8), which favors the development of aquatic organisms. Optimum depth helps establish lake stratification and ensures ecological stability. This applies to post-mining lakes as well; an optimum depth should be determined to ensure the development of thermal stratification, which affects lake processes.     

Towards Regulatory Criteria for Discharging Iron-rich Mine Water into the Sea

Appropriate criteria are needed for regulating the discharge of mine water into the sea. Simply applying criteria developed for freshwater ecosystems to marine settings would be naïve and highly inappropriate because marine organisms have very different mechanisms for coping with high concentrations of cations than do freshwater species. Furthermore, the hydrodynamics and geochemistry of marine waters mean that certain processes that are very important in determining the magnitude of mine water impacts in freshwater ecosystems are largely irrelevant in the oceans. This is particularly the case relative to benthic smothering by ochre, which does not occur when mine waters are discharged to the sea. Visual impacts of mine water discharge are still important in marine systems, due to the possibility of developing unsightly “slicks” of suspended ochre on the water surface (albeit these are actually innocuous in ecological terms). Avoidance of ochre slicks is a common concern wherever ferruginous mine waters are discharged to coastal waters. Compilation of data from a range of case studies indicates that no visible plume of ochre would be expected where the rate of iron release is less than about 200 kg/day. Maintenance of iron loadings below this critical threshold can be ensured by calculating a target maximum iron concentration (Fe_MAX, in mg/L) for the final effluent (which must be achieved by treatment if necessary) using the simple formula: Fe_MAX = 2,314.8/Q _MAX, where Q _MAX is the maximum anticipated flow rate in litres per second from the mined system (pumped or flowing by gravity).     

Effect of <Emphasis Type="Italic">Pseudomonas Japonica</Emphasis> bacteria on selection of sulfides

The industrial-level tests prove efficiency of Pseudomonas Japonica bacteria in production of copper–molybdenum bulk concentrate. Using scanning electron microscopy, it is found that adsorption of Pseudomonas Japonica bacteria takes place at the points of xanthate attachment. The infrared spectroscopy analysis shows that after treatment with the bacteria, C–O and C=S bonds vanish while valence and deformation vibrations in CH_3- and CH₂ groups become less intensive, which may be reflective of desorption of xanthate from the mineral surface.     

Removal of Turbidity from Travertine Processing Wastewaters by Coagulants,Flocculants and Natural Materials

The sedimentation behaviour of travertine-processing wastewater containing a high concentration of suspended solids was investigated using different coagulation and flocculation methods. In batch experiments, four types of coagulants [FeC1₃, Al₂(SO₄)₃, PACl, NaAlO₂], six types of flocculants (40% MMW–40% HMW cationic, 30% MMW, 40% MMW, 40% HMW anionic and nonionic) and three types of natural materials (NMs) (sepiolite, zeolite, and pumice) were used to treat wastewater with an initial turbidity of 570–880 NTU. The optimum process conditions (dosage, mixing time/speed, sedimentation time, and pH) were investigated for each. Sedimentation performance was assessed by the effluent turbidity (T _eff) values of the treated water. The best performances obtained were 99.3% (T _eff?=?4 NTU), 99.1% (T _eff?=?8 NTU), and 97.8% (T _eff?=?18 NTU) with 40% HMW anionic-cationic flocculants, zeolite, and FeCl₃, respectively. Sludge properties, including sludge settling velocity (mm/min), sludge density (g/cm³), suspended solids (SS) content (mg/L), and sludge solids (%) were determined and compared under optimized conditions. The type of additive significantly affected performance. Travertine processing wastewater flocculation with polymeric materials and NMs, especially zeolite, was more favourable than coagulants in terms of both turbidity removal and sludge quality. Since zeolite is a NM, additional studies on using and recycling of the generated sludge as an industrial feedstock would be worthwhile.     

Biotic and Abiotic Sequestration of Selenium in Anoxic Coal Waste Rock

Mobile selenium oxyanions (\({\text{S}}{{\text{e}}^{{\text{VI}}}}{\text{O}}_{4}^{{2 - }}\) and \({\text{S}}{{\text{e}}^{{\text{IV}}}}{\text{O}}_{3}^{{2 - }}\)) can be sequestered by biotic or abiotic reduction to non-mobile species or by adsorption to mineral surfaces. Microbial analyses and geochemical batch testing with samples collected from a coal waste rock dump in the Elk Valley, British Columbia, Canada were conducted to assess whether Se can be sequestered in anoxic, waste rock by these mechanisms. Bacteria that reduce Se(IV) and Se(VI) to Se(0) were isolated from the waste rock. Isolates that reduce Se(IV) to Se(0) were present in a water sample collected from an underlying rock drain. Three isolates were affiliated with Pseudomonas and Arthrobacter. One isolate was a putatively novel species. The production of Se(0) was confirmed by X-ray absorption near edge spectroscopy of a red precipitate isolated from a broth media containing rock-drain water. No adsorption or reduction of Se(VI) was observed in anoxic, abiotic (sterile) batch tests conducted with waste rock and a 1.0 mg/L Se(VI) solution, whereas Se(IV) was adsorbed by the waste rock and subsequently reduced to Se(0) in abiotic batch tests with a 0.7 mg/L Se(IV) solution. In non-sterile batch tests using waste rock and rock-drain water (0.39 mg/L Se(VI)), Se(VI) was biologically reduced to Se(IV), which was subsequently removed from solution by a combination of bioreduction, adsorption, and possibly abiotic reduction. This study suggests that, under anoxic conditions, Se sequestration in waste rock may occur via biotic reduction of Se(VI) to Se(IV) followed by adsorption of Se(IV) and abiotic and biotic reduction of Se(IV) to Se(0).     

Tailings Mineralogy and Geochemistry at the Abandoned Haveri Au–Cu Mine,SW Finland

Fourteen samples from the Haveri Au–Cu mine tailings were studied by reflected-light microcopy, scanning electron microscopy, X-ray powder-diffraction, and sequential extraction methods, and 12 water samples were analyzed for total and dissolved elements to delineate the extent of sulfide oxidation and its impact on nearby surface waters. Water-soluble, adsorbed-exchangeable-carbonate (AEC), Fe (oxy)hydroxides, Fe oxide, and Fe sulfide fractions were extracted sequentially. The oxidation layer was found to vary from 50 to 140 cm: the upper part was nearly depleted in primary sulfides, especially pyrrhotite [Fe_(1?x)S] and pyrite (FeS₂); in the lower part, discontinuous cemented layers were detected. Secondary Fe (oxy)hydroxides and Fe oxyhydroxysulfates were abundant in the oxidation layer and were slightly enriched in trace elements, including As (up to 80 mg/kg), Cu (300 mg/kg), and Zn (150 mg/kg). Almost half of the As (average 25 mg/kg) were present as secondary minerals susceptible to redissolution. The pH of the vadose tailings varied from 2.46 to neutral, and the total sulfur content varied from 1 to 6.5% (average 2.9%). Aqua regia extraction showed that the Haveri tailings are characterized by low concentrations of the elements Cd, Cr, Pd, and slightly elevated concentrations of As, which are present at very low concentrations in the surface water (<6 μg/L). However, runoff that flows on top of the tailings and discharges into the nearby lake carries Co, Cu, Ni, and Zn (concentrations of each range from 500 to 1,800 μg/L). Additionally, dissolution of sulfides and Fe precipitates may mobilize trace metals in the ground water. Thus, overall, there is a small continuous release of AMD into Lake Kirkkojärvi, but the environmental impacts to the lake are presently small.     

Hydrogeochemistry and Contamination of Trace Elements in Cu-Porphyry Mine Tailings: A Case Study from the Sarcheshmeh Mine,SE Iran

Geochemical and hydrochemical investigations were performed to understand the contamination potential of the Sarcheshmeh mine tailings. The geochemical mobility for the tailings is as follows: Cu > Cd > Co > Zn > Ni > Mn > S > Cr > Sn > As > Se > Fe = Bi > Sb = Pb = Mo. Highly mobile and contaminant elements (Cd, Cu, Zn, Mn, Co, Ni, S, and Cr), which significantly correlated with each other, were mainly concentrated in the surface evaporative layer of the old, weathered tailings, due to the high evaporation rate, which causes subsurface water to migrate upward via capillary action. The contamination potential associated with the tailings is controlled by: (1) dissolution of secondary evaporative soluble phases, especially after rainfall on the old weathered tailings, accompanied by low pH and high contamination loads of Al, Cd, Co, Mg, Cr, Cu, Mn, Ni, S, Se, and Zn; (2) processing of the Cu-porphyry ore under alkaline conditions, which is responsible for the high Mo (mean of 2.55 mg/L) and very low values of other contaminants in fresh tailings in the decantation pond; (3) low mobility of As, Fe, Pb, Sb, Mo, and Sn due to natural adsorption and co-precipitation in the tailings oxidizing zone. Speciation modeling showed that sulfate complexes (MSO₄ ⁺, M(SO₄)_(aq), M(SO₄) ₂ ^?2 , and M(SO₄) ₂ ^? ) and free metal species (M⁺² and M⁺³) are the dominant forms of dissolved cations in the acidic waters associated with the weathered tailings. In the alkaline and highly alkaline waters, trace element speciation was controlled by various hydroxide complexes, such as M(OH)⁺, M(OH) ₃ ^? , M₃(OH) ₄ ⁺² , M₂(OH) ₃ ⁺ , M(OH)_2(aq), M(OH) ₄ ^?2 , Me(OH) ₂ ⁺ , Me(OH) ₄ ^? , Me(OH) ₂ ⁺ , Me(OH)_3(aq), and Me(OH) ₄ ^? (where M represents bivalent and Me represents trivalent cations). The speciation pattern of As, Mo, and Se is mainly dominated by oxy-anion forms. The obtained results can be used as a basis for environmental management of the Cu-porphyry mine tailings.     

Gas diffusion coefficient in coal: calculation of tangent slope accuracy through the inflection point determination

This investigation aims to develop an accurate method to calculate the tangent slope (b) - a fundamental parameter to calculate gas diffusion coefficients under different pressures - using inflection point determinations. The authors also studied the different tangent slope behaviours depending on the experimental gas sorption used. The single Langmuir model for individual gases and the extended Langmuir model, for multicomponent gas mixtures were applied to fit experimental gas sorption isotherm data. Two coals were selected in order to minimize and/or avoid the maceral composition and vitrinite mean random reflectance effects. Samples were submitted to three different gas compositions, viz. 99.999% CH₄; 99.999% CO₂; and a gas mixture containing 74.99% CH₄ + 19.99% CO₂ + 5.02% N₂. Results showed that the first and the second derivatives calculated to define the first inflection points represent exactly the final limit of tangent slopes.     

Virtual prototype simulation of hydraulic shovel kinematics for spatial characterization in surface mining operations

Hydraulic shovels are large-capacity equipment for excavating and loading dump trucks in constrained surface mining environments. Kinematics simulation of such equipment allows mine planning engineers to plan, design and control their spatial environments to achieve operating safety and efficiency. In this study, a hydraulic shovel was modelled as a mechanical manipulator with five degrees of freedom comprising the crawler, upper, boom, stick, bucket and bucket door components. The model was captured in a schematic diagram consisting of a six-bar linkage using the symbolic notation of Denavit and Hartenberg (Ho and Sriwattanathmma 1989 Ho, C. Y. and Sriwattanathmma, J. 1989. Robot Kinematics Symbolic Automation and Numerical Synthesis, Norwood, NJ: Ablex.  [Google Scholar]). Homogeneous transformation matrices were used to capture the spatial configuration between adjacent links. The forward kinematics method was used to formulate the kinematics equations by attaching Cartesian coordinates to the schematic shovel diagram. Based on the kinematics model, a 3D virtual prototype of the hydraulic shovel was built in the Automatic Dynamic Analysis of Mechanical Systems (ADAMS) environment to simulate the motions of the hydraulic shovel with selected time steps. The simulator was validated using real-world data with animation and numerical analysis of the digging, swinging and dumping motions of the shovel machinery. The superimposed display of the deployment of the hydraulic shovel in three phases allows a detailed motion examination of the system. The numerical results of linear and angular displacements of the bucket tip and bucket door can be used to analyse the kinematics motion of the hydraulic shovel for its optimization. This simulator provides a solid foundation for further dynamics modelling and dynamic hydraulic shovel performance studies.     

Whitefish (<Emphasis Type="Italic">Coregonus lavaretus</Emphasis>) Response to Varying Potassium and Sodium Concentrations: A Model of Mining Water Toxic Response

Boreal waters are typically low in minerals and oligotrophic, and therefore particularly sensitive to changes in mineral composition. We investigated the effects of potassium and the potassium: sodium (K⁺: Na⁺) ratio in freshwater on growth performance and oxidative stress in a typical northern species of whitefish, Coregonus lavaretus. Fish were subjected to 0.8 mM Na and 4.4 mM K, which corresponds to the K⁺:Na⁺ ratio in a lake contaminated by mining wastes from the Kostomuksha iron mine and ore dressing mill in northwestern Russia. The control group was subjected to water with similar mineralization levels and equal amounts of Na and K (approximately 0.3 mM of each). Potassium excess caused a decrease in fish growth rate and oxidative stress, as indicated by the level of lipid peroxidation product malondialdehyde (MDA). Glutathione-S-transferase (GST) activity and the level of reduced glutathione (GSH) were not affected by cation composition.     

Assessment of Soil and Water Contamination at the Tab-Simco Coal Mine: A Case Study

In 1996, the Tab-Simco site, an abandoned coal mine 10 km southeast of Carbondale, Illinois, was listed as one of the most highly contaminated AMD sites in the mid-continent region. A suite of impacted soil and water samples were collected from various locations to characterize the current extent of AMD pollution, following standard U.S. EPA protocols. The mean pH of soil and water samples were found to be 2.69 and 2.07, respectively. The mean sulfur content of the soil samples was 0.5 %. The AMD-impacted soils contained high concentrations of Fe, Zn, Ni, Cr, Cu, Pb, and As. The AMD also contained high concentrations of Fe, As, Zn, Pb, Cr, Al, Cd, Cu, and Ni, as well as \({\text{SO}}_{4}^{2 - }\), all of which were significantly above their U.S. EPA permissible limits for surface water.     

Removal of Trace Metals from Acid Mine Drainage Using a Sequential Combination of Coal Ash-Based Adsorbents and Phytoremediation by Bunchgrass (Vetiver [<Emphasis Type="Italic">Vetiveria zizanioides</Emphasis> L])

Potentially scalable low-cost treatment methods for acid mine drainage (AMD) are very limited. We used a sequential combination of adsorption and phytoremediation by bunchgrass (Vetiver [Vetiveria zizanioides L]) in a semi-batch system to remove Zn, Mn, Ni, and Cu from AMD. The objectives were: (1) to compare the removal of these metals by raw and NaOH-activated coal ash (NaOH-CA); and (2) to determine the effect of sequencing adsorption and phytoextraction on metal removal. The NaOH-CA adsorbed significantly more metals than raw coal ash (RCA) in both batch and semi-batch fixed column experiments, demonstrating the effectiveness of NaOH hydrothermal activation, which forms zeolites. Adsorption by NaOH-CA removed 59.1, 95.7, 67.6, and 77.9% of the Zn, Mn, Ni, and Cu, respectively, compared to 50.6, 95.1, 30.2, and 60.5% for the RCA. Metal removal by phytoremediation was generally less than that by adsorption, accounting for between 3.4 and 54.6% for both adsorbents. Phytoremediation following adsorption by NaOH-CA removed 89.2–99.9% of the metals compared to 70.8–98.5% when phytoremediation followed adsorption by RCA. Overall, relatively high metal removal efficiencies were attained, considering the acidic conditions (pH?<4), at hydraulic residence times of 1 to 5 days. Using coal ash to treat AMD is potentially a low-cost and environmentally friendly option for minimizing the adverse public health and environmental risks associated with both wastes.     

Die Erneuerung der Klinkerproduktion der Zementwerk LEUBE GmbH in St. Leonhard/Österreich

After conducting intensive studies as well as a feasibility study, Zementwerk LEUBE GmbH has taken the decision to install a new kiln line. Aims of the project were high fuel substitution rates, low energy consumption as well as lowest possible emissions simultaneously with a high degree of flexibility of the plant. The project investment of approximately 31.5 mio. € includes as follows:

• Raw meal dosing
• 5-stage preheater with calciner and combustion chamber in concrete structure with steel platforms
• Shift of an existing rotary kiln
• Kiln hood and grate cooler
• Cooler exhaust air filter
• Fuel handling (alternative fuel for calciner)
• Clinker transport
• Necessary connections to existing feeding and exhaust gas handling

The project was executed by a LEUBE team with a specialized EPCM-team (Engineering Procurement Consulting Management-Team) from A TEC Production & Services GmbH. The project started on 22 July 2009. The first clinker was produced on 20 October 2010 after an accident-free total erection phase of 15 months. After more than 4 years of production experience it can be summarized that all expectations and all guarantee values have been completely fulfilled. The yearly reduction of coal consumption amounts to approximately 8000 tons which correspond to a fuel substitution rate of approximately 70?%. The electric power consumption was reduced by approximately 20?% compared to the old kiln lines. The strict emission limits in the tourism area of Salzburg could be met without any difficulties. With the new kiln line it is possible to adapt the production according to the seasonal fluctuating cement sales (the production ratio is between 1000 tpd and 2000 tpd clinker). The system demonstrates an extremely high degree of flexibility in terms of different fuels, raw materials and throughput. Additional modifications in the area of raw mill and exhaust gas filter were effected in 2011/2012, which secures the clinker production at the plant in St. Leonhard in the future.