Advanced oxidation of catechol in reverse osmosis concentrate generated in leather wastewater by Cu–graphite electrode

Reverse osmosis (RO) concentrate generated from tannery was treated by advanced electrochemical oxidation using graphite electrodes. Catechol was selected as model organic pollutant in the RO concentrate. The influence of applied current density, catechol concentration, pH, temperature and inner electrode space of electrodes was investigated in electrochemical oxidation system. The optimized conditions were found to be current density (j), 100 mA/cm²; electrolysis time (t _eco), 60 min; pH, 7.0; and temperature, 25 °C at an inner electrode space, 2 cm. The average mass transport coefficient for the removal of catechol as COD was found to be 3.0 × 10^?5 m/s at optimum conditions. Faradic efficiency and specific energy consumption were also calculated for the applied current density. Further, the treatment of catechol was confirmed through Fourier transform infrared spectroscopy. Theoretical evaluation of current density suggested that the removal of catechol was controlled when supplied at above limiting applied current densities and mass transport controlled at lower of limiting current densities.     

Methane formation in soil–plant systems treating wastewater as influenced by microbial populations

The present study evaluated the effect of plant species on methane (CH₄) emission and microbial populations in three types of soil–plant systems. Results showed large variation of CH₄ flux rate ranging from 1.35 to 212.61 mg CH₄ m^?2 h^?1. Emission peak of CH₄ occurred in July. No significant difference was found in the non-vegetation system spanning 2 years. Compared with non-vegetation, vegetation systems had much higher flux of CH₄, and obvious seasonal variation was observed. The polyculture system planted with Zizania latifolia (Z. latifolia) and Phragmites australis (P. australis) released higher CH₄ fluxes than the mono system (P. australis), reflecting that Z. latifolia growth could simulate CH₄ emission. The fluorescence in situ hybridization (FISH) results support the characteristics of CH₄ fluxes. Much higher methanotrophs amount and lower methanogens amount from the mono system than those from the polyculture system was observed indicating that Z. latifolia growth may limit the oxygen transportation resulting in higher CH₄ emission. The polyculture system has the highest potential of CH₄ emission.     

Fate of aluminium released by sacrificial anodes – Contamination of marine sediments by environmentally available compounds

To protect their steel structures from corrosion by cathodic protection, many harbours use aluminium sacrificial anodes, which induces aluminium release and potential contamination of the surrounding waters and sediments. To study the impact on Al mobility, a natural marine sediment was artificially contaminated with aluminium from different sources: sulphate or chloride salts, or sacrificial anodes. To estimate Al mobility in sediments, single (HCl) and sequential (F6) extractions were performed; they highlighted that aluminium is poorly mobile in natural sediment (HCl-leachable: 2% and F6-leachable: 9%). Contamination by aluminium salts inhibits HCl-leachability (≤ 2%), whereas the Al F6-leachability is intensified up to 18%, suggesting that the additional aluminium is scavenged in a mobile fraction that HCl is not able to solubilise. In case of aluminium anode contamination, sediments present surging Al HCl-leachable (15%) and F6-leachable (32%) fractions, which are related to aluminium mineralogical speciation. Indeed, contrary to the Al naturally present or introduced by salts, Al released by anodes is partly bound to the acid-soluble fraction, probably because of the integration of the released Al into the calcareous deposit produced at the anodes surfaces that finally comes away and gets mixed up with the sediment. The presence of aluminium in the acid-soluble fraction of sediments could have an important environmental impact as this fraction is easily available. Indeed, Al scavenged in the acid-soluble fraction of sediments participates in enhancing Al lability near the sacrificial anodes and may affect the surrounding ecosystems.     

Preliminary analysis on roles of metal–organic compounds in the formation of invisible gold

The paper comprises new analytical data on the nature and occurrence of gold in solid pyrobitumen, closely associated with the main gold-bearing sulfide arsenic ores of the Bakyrchik gold deposit (Kazakhstan), related to post-collisional magmatic-hydrothermal origin. Gold mineralization of the deposit occurs mainly in the form of an “invisible” type of gold in the structures of arsenian pyrite and arsenopyrite, and the form of gold-organic compounds of pyrobitumen in carbonaceous-terrigenous sequences of Carboniferous formation. Microscopic and electron microscopic analysis, Raman and FT-Infrared analysis, mineralogical and three-step sequential extraction analysis (NH₂OH·HCl, H₂O_2, HNO₃ + HCl) has been carried out using 9 ore samples (from 3 different types of ores) for a comprehensive study of pyrobitumen and sulfide arsenic ores focusing mainly on organic matter. The sequentially extracted precious metal content of pyrobitumen reaches up to 7 ppm gold and other metals like Ag 4 ppm, Pt 31 ppb, and Pd 26 ppb, forming metal–organic compounds, while arsenic sulfide minerals incorporate 11 ppm gold, 39 ppm Ag, 0.49 ppm Pt. The enrichment of gold associating with organic matter and sulfide ore minerals was confirmed in this study. Organic matter was active in the migration of gold and the capture of gold by pyrobitumen. Moreover, the reductive organic matter agent released gold, most likely for the sulfide arsenic ore minerals. Pyrobitumen was a decisive factor in the concentration, transportation, and preservation of gold in the deposit.

     

Potential use of faujasite–phillipsite and phillipsite–chabazite tuff in purification of treated effluent from domestic wastewater treatment plants

Characterization of zeolitic tuff from Jabal Hannoun (HN) and Mukawir (MR) was carried out to examine the ability of using low-cost natural materials in domestic wastewater treatment. The grain size between 0.3 and 1 mm (0.3–1 mm) of the HN and MR has the highest total zeolite grade (faujasite–phillipsite and phillipsite–chabazite) and suitable cation exchange capacity. They were used as fixed-bed ion exchangers and adsorbents. The zeolitic tuff efficiently removed the organic and nitrogen compounds, Pb and Zn from the effluent. One bed volume (1 BV) of the zeolitic tuff is capable to remove up to 95 % of total organic carbon form 500 BV of the effluent. The removal percent of total nitrogen by HN and MR is close to 95 and 90 %, respectively. The zeolitic tuff has an excellent efficiency to remove Pb and Zn from the effluent. 1 BV of HN completely cleans Zn and Pb from 680 and 730 BV of the effluent, respectively, whereas 1 BV of MR is able to clean completely Zn and Pb from 500 and 685 BV of the effluent, respectively. The greater performance of the HN compared with the MR may be explained by its higher zeolites grade and presence of faujasite.     

Continuous process study on simultaneous nitrification–denitrification of high ammoniacal nitrogen load wastewater in aerobic–anoxic sequencing bioreactors

The study focused on the feasibility of high NH₄ ⁺–N (400–600 mg/L) and COD load at two different hydraulic retention times (HRTs = 36 and 24 h) in two identical aerobic–anoxic sequencing bioreactors which were constructed in series in a single system using a specifically designed single biomass containing autotrophic nitrifying and heterotrophic denitrifying bacteria. Internal recirculation of synthetic wastewater from one tank to other was not carried out like the conventional aerobic–anoxic processes. Cycles of 15 days under sequences of aerated and non-aerated periods of three hour each were repeated during each continuous flow experiment conducted. Sodium bicarbonate and sodium acetate were selected as the appropriate inorganic and organic carbon sources. The results showed that the HRT may not affect the simultaneous nitrification and denitrification processes. Average nitrification ratio was obtained to be above 20 mg/L NH₄ ⁺–N/h daily. Results of 90 days’ operation also showed high removal efficiencies of ammoniacal nitrogen of about 83% daily. The main advantage of this process includes efficient ammoniacal nitrogen removal without separated aerobic and anoxic tanks, decrease operating costs due to the lesser oxygen concentration requirement in the bioreactors.     

Sequestration of As and Mo in uranium mill precipitates (pH 1.5–9.2): An XAS study

As- and Mo- bearing secondary mineral phases formed during the neutralization of uranium mill wastes require characterization. Previous studies indicate that arsenate and molybdate adsorbed to ferrihydrite are the dominant controls in the tailings materials. A lab-scale plant was employed to characterize secondary precipitates from a variety of ore blends. Through total elemental analysis of precipitates and As and Mo K-edge X-ray absorption spectroscopy, different ratios of contributing phases were determined for each pH stage (4.2, 6.5, and 9.2) of the neutralization process. Overall, arsenate adsorbed to ferrihydrite was the dominant As mineral phase regardless of pH or sample blend (53–77%), with fractional contribution from ferric arsenates, and adsorption to aluminum phases. Molybdate adsorbed to ferrihydrite was the dominant Mo mineral phase, with fractional contribution decreasing with increasing pH (100–69%). The characterization of these phases in the secondary precipitates provides further understanding of the contributing mineral species in tailing facilities.     

Simultaneous nitrification–denitrification of wastewater: effect of zeolite as a support in sequential batch reactor with step-feed strategy

One of the technologies used for wastewater nitrogen removal consists in simultaneous nitrification–denitrification. The low microbial growth rate and the low availability of organic material for the denitrification stage make it necessary to study new operational conditions and the use of microbial supports. The aim of this study was to evaluate the operational behavior of a simultaneous nitrification–denitrification process in a sequential batch reactor utilizing zeolite as a biomass support and step-feed strategy. Two reactors of 2 L were used, one with zeolite and another without zeolite, both operated at constant temperature (31 °C), varying nitrogen loading rate (NLR) from 0.041 to 0.113 kg total Kjeldahl nitrogen (TKN/m³/day). After 209 days, removals higher than 86 and 96 % in nitrogen compounds and organic matter were obtained, respectively. There was not accumulation of nitrate and nitrite in any case; this means that there was a simultaneous nitrification–denitrification in the reactors. The incorporation of zeolite in the system held higher concentration of biomass in the reactor; this led to reduce start-up to 21 days and to improve 11.31 % removal kinetic. The use of a step-feed strategy prevents events of inhibition by substrate, even duplicating tolerance to higher NLR for the same operation time.     

Sources of Eocene Magmatism in Western Kamchatka by the Geochemical and Sr–Nd–Pb Isotope Characteristics of Basites

Doklady Earth Sciences - The isotope and geochemical characteristics of Eocene–Oligocene igneous rocks of Western Kamchatka were studied. It was shown that igneous rocks of the Eocene Kinkil...     

Intermetallic compounds,copper and palladium alloys in Au–Pd ore of the Skaergaard pluton,Greenland

Copper–palladium intermetallic compounds and alloys (2314 grains) from the Au–Pd ore of the Skaergaard layered gabbroic pluton have been studied. Skaergaardite PdCu, nielsenite PdCu₃, (Cu,Pd)_β, (Cu,Pd)_α, (Pd,Cu,Au,Pt) alloys, and native palladium have been identified as a result of 1680 microprobe analyses. The average compositions and various chemical varieties of these minerals are characterized, as well as vertical and lateral zoning in distribution of noble metals. The primary Pd–Cu alloys were formed within a wide temperature interval broadly synchronously with cooling and crystallization of host gabbro and in close association with separation of Fe–Cu sulfide liquid. In the course of crystallization of residual gabbroic melt enriched in iron, noble and heavy metals and saturated with the supercritical aqueous fluid, PGE and Au are selectively concentrated in the Fe–Cu sulfide phase as Pd–Cu and Cu–Au alloys.     

Delineation of mineralization zones in porphyry Cu deposits by fractal concentration–volume modeling

The purpose of this study was to identify the various mineralization zones especially supergene enrichment and hypogene in two different Iranian porphyry Cu deposits, based on subsurface data and by using the proposed concentration–volume (C–V) fractal method. The Sungun and Chah-Firuzeh porphyry Cu deposits, which are situated in NW and SE Iran, respectively, were selected for this study. Straight lines fitted through log–log plots showing C–V relations for Cu were employed to separate supergene enrichment and hypogene zones from oxidation zones and barren host rocks in the two deposits and to distinguish a skarn mineralized zone from the hypogene zone in Sungun deposit. In the proposed C–V fractal method, the identification of mineralization zones is based on power–law relationships between Cu concentrations and the volume of rocks hosting porphyry Cu mineralization. Separate subsurface data from the two deposits were analyzed by C–V fractal method and the results have been compared with geological models which included alteration and mineralogical models. The comparison shows that the interpreted zones based on the C–V fractal method are consistent with the geological models. The proposed C–V method is a new approach to defining zones in a mineral deposit and there was no commercial software available to perform the relevant calculations; therefore, a fractal concentration–volume (FCV) software was designed by the authors to achieve this goal.     

Contamination of water and soil by the Erdenet copper–molybdenum mine in Mongolia

As one of the largest copper–molybdenum (Cu–Mo) mines in the world, the Erdenet Mine in Mongolia has been active since 1978 and is expected to continue operations for at least another 30 years. In this study, the potential impacts of mining activities on the soil and water environments have been evaluated. Water samples showed high concentrations of sulfate, calcium, magnesium, Mo, and arsenic, and high pH values in the order of high to low as follows: tailing water > Khangal River > groundwater. Statistical analysis and the δ²H and δ¹⁸O values of water samples indicate that the tailing water directly affects the stream water and indirectly affects groundwater through recharge processes. Soil and stream sediments are highly contaminated with Cu and Mo, which are major elements of ore minerals. Based on the contamination factor (CF), the pollution load index (PLI), and the degree of contamination (C_d), soil appears to be less contaminated than stream sediments. The soil particle size is similar to that of tailing materials, but stream sediments have much coarser particles, implying that the materials have different origins. Contamination levels in stream sediments display a tendency to decrease with distance from the mine, but no such changes are found in soil. Consequently, soil contamination by metals is attributable to wind-blown dusts from the tailing materials, and stream sediment contamination is caused by discharges from uncontained subgrade ore stock materials. Considering the evident impact on the soil and water environment, and the human health risk from the Erdenet Mine, measures to mitigate its environmental impact should be taken immediately including source control, the establishment of a systematic and continuous monitoring system, and a comprehensive risk assessment.     

Evolution of organic matter in lignite-containing sediments revealed by analytical pyrolysis (Py–GC–MS)

Newly vegetated sites provide opportunities to enlighten organic matter (OM) transformation mechanisms in soils and sediments at very early stages of development which, in turn, is relevant to better understand general ecosystem functioning. Mine acid soils and sediments in the Lusatian open cast lignite mining district (Germany) contains a high concentration of fossil carbon (lignite) in ad mixture with recent OM from the local vegetation, both contributing to the humified OM pool. In this study, analytical pyrolysis (Py–GC–MS) was used to monitor the different C sources (lignite or plant derived) in developing mine tailing soils and sediments and their degree of degradation in contrasting environments. Representative vegetation and the organic carbon (OC) rich soil/sediment fraction (humus fraction) were sampled at two depths (0–5 and 5–10 cm) in three plots along a transect covering an upland forest soil, a partially submerged sediment at the land–water interface and a constantly submerged sediment. The analysis of plant (lipds, isoprenoids, methoxyphenols and carbohydrates) and possible lignite (alkyl napththalenes, alkyl benzenes and PAHs) biomarkers released after pyrolysis supports previous findings in the area using other proxies. It was possible to discern OM sources in soil/sediment humus fractions, both from the substrate (lignite) as well as from the prevailing vegetation of the area. Environmental conditions in the submerged sediment seem to favour OM protection and the accumulation of decomposing plant material, whereas more intense OM degradation seems to prevail in the land–water interface areas characterized by fluctuating water level. In addition, a well resolved series of organic sulfur compounds (OSCS) found in the submerged sediments of rehabilitated acid lakes, indicates the possible occurrence of particular mechanisms of C preservation in this extreme anoxic S rich environment, i.e. via sulphur “quenching” with plant derived lipids during early diagenesis.     

Research on the direction of secondary migration of oil by making use of nitrogen compounds as tracers in the No. 6 area of the Melut Basin

1 IntroductionThe application of isomeric-nitrogen compounds astracers to oil-migration research is a piece of innovatorywork, and also a newbreakthrough made in non-hydro-carbon geochemistry research. At present, a lot ofwork has been done on nitrogen co…     

Investigating the origin of Pb pollution in a terrestrial soil–plant–snail food chain by means of Pb isotope ratios

Lead isotope ratios were used to trace the origin of Pb in a soil–plant (Urtica dioica)–snail (Cepaea nemoralis) food chain in two polluted locations in the floodplains of the rivers Meuse and Rhine (Biesbosch National Park) and one reference location in the Netherlands. Lead isotope ratios and concentrations were determined in soil, litter, plant leaves, snails, rainwater and airborne particulate matter. Anthropogenic Pb in the soils of all locations was found to be derived from deposition of Pb polluted river sediments. Discharging rivers influenced the reference location before being reclaimed from the sea. The river sediment contains anthropogenic Pb from various sources related to industrial activities in the hinterland of the rivers Meuse and Rhine. Lead in the atmosphere contributed substantially to Pb pollution and Pb transfer in plant leaves and snails in all locations. Lead pollution in plant leaves and snails can be explained from a mixture of river sediment-Pb and atmospheric Pb from various transfer routes that involve low concentrations.     

Timing of eclogite facies metamorphism in the southernmost Scandinavian Caledonides by Lu–Hf and Sm–Nd geochronology

The Scandinavian Caledonides contain several non-cogenetic eclogite-bearing terranes that were metamorphosed before the main orogenic stage in Scandian time (430–395 Ma). Although petrological and geochronological data from these terranes have provided essential information on the geodynamic history of the Caledonian orogenic cycle, the general picture is still patchy. To refine existing geodynamic models, we have dated the eclogite occurrence in the Jæren nappe, SW Norway, by Lu–Hf and Sm–Nd geochronology. Five out of the six studied samples provide a weighted mean Lu–Hf age of 469.9 ± 1.2 Ma (±2σ). One sample provided a significantly younger age of 457.9 ± 2.4 Ma. Garnet from the younger sample grew exclusively at eclogite facies conditions. In contrast, garnet from the other samples comprises prograde cores and peak metamorphic rims. Age estimates that take Lu-contributions of each zone into account provide an age of 471.0 ± 0.9 Ma for the cores and suggest a ca. 455 Ma age for the rims, which is identical to the bulk-garnet age of the younger sample. The same pattern is indicated by Sm–Nd ages, although these are relatively imprecise and reflect isotopic disturbance during thermal overprinting upon exhumation. The data define a new high-pressure age population for the Scandinavian Caledonides, which allows more detailed insight into the subduction history that affected the Baltoscandian margin before Scandian continental collision. Furthermore, this study highlights the potential complexities involved in garnet geochronology and shows the strength of Lu–Hf dating for unraveling the geochronological record of HP rocks.     

Identification of geochemical anomalies by using of number–size (N–S) fractal model in Bardaskan area, NE Iran

Geochemical anomaly separation and identification using the number–size (N–S) model at Bardaskan area, NE Iran is studied in this paper. Lithogeochemical data were used in this study which was conducted for the exploration for Au and Cu mineralization and enrichments in Bardaskan area. There are two major mineralization phases concluded epithermal gold and a disseminated systems. N–S log–log plots for Cu, Au, Sb, and As illustrated multifractal natures. Several anomalies at local scale were identified for Au (32 ppb), Cu (28 ppm), As (11 ppm), and Sb (0.8 ppm) and the obtained results suggest existence of local Au and Cu anomalies whose magnitudes generally are above 158 and 354 ppm, respectively. The most important mineralization events are responsible for presence of Au and Cu at grades above 1,778 and 8,912 ppm. The study reveals threshold values for Au and Cu are a consequence of the occurrence of anomalous accumulations of phyllic and silicification alteration zones and metamorphic rocks especially in tuffaceous sandstones and sericite schist types. The obtained results were correlated with fault distribution patterns, revealing a positive direct correlation between mineralization in anomalous areas and the faults present in the mineralized system.     

Glass at endocontacts of granite massifs in Volcanic–Plutonic belts (Exemplified by granite of Central Kazakhstan)

Glass formation takes place under conditions of rapid cooling of a melt at a great temperature difference between the melt and the host rock, which must have high thermal conductivity. The most favorable conditions for glass formation exist when the melt intrudes in the form of thin apophyses. Glass has been found in granite massifs related to the volcanic–plutonic association.