Indigenous Iron Research Articles

Fe(II)/Fe(III) cycle actuating a novel process to remove organics in waste pit mud from Maotai: Performance and mechanism

In this study, a novel method relying on iron cycle through intermittent aeration was proposed to treat organic matter in waste sealed pit mud from Moutai. Firstly, ferrihydrite was used to verify dissimilatory iron reduction could remove organics from the pit mud; then, the effect of iron cycle induced by intermittent aeration on organics was investigated. The results showed that the removal efficiency of organics was increased by 8.2 % after the addition of ferrihydrite, then intermittent aeration was carried out, Fe(II) content decreased after aeration and increased again after stopping aeration, indicating that iron cycle occurred. Additionally, the total chemical oxygen demand (TCOD) content further decreased by18.8 % in the reactor with intermittent aeration, significantly higher than that in the unaerated group (11.8 %) (p < 0.05). Due to the short aeration time (about once a week, 200–500 mL/min, 30 min for each aeration), aerobic microorganisms were undetected, which further indicated that iron cycle enhanced the removal of organics. Finally, intermittent aeration was conducted in the fermentation system of pit mud without adding iron, and the indigenous iron in the pit mud was also recycled. After 31 days, the TCOD removal efficiency increased by 15.6 % in the aeration group compared with that in the control group. Microbial analysis showed that some microorganism that degraded refractory organics, including iron reducing bacteria, were enriched in the aerated reactors, such as WCHB1–32, ADurb. bin053–1, Lentimicrobium, and Aneurinibacillus, Geobacteraceae. These indicated that organic matter removal can be enhanced by relying on its indigenous iron.

Fe(II)Cl2 amendment suppresses pond methane emissions by stimulating iron-dependent anaerobic oxidation of methane.

Aquatic ecosystems are large contributors to global methane (CH4) emissions. Eutrophication significantly enhances CH4-production as it stimulates methanogenesis. Mitigation measures aimed at reducing eutrophication, such as the addition of metal salts to immobilize phosphate (PO43-), are now common practice. However, the effects of such remedies on methanogenic and methanotrophic communities-and therefore on CH4-cycling-remain largely unexplored. Here, we demonstrate that Fe(II)Cl2 addition, used as PO43- binder, differentially affected microbial CH4 cycling-processes in field experiments and batch incubations. In the field experiments, carried out in enclosures in a eutrophic pond, Fe(II)Cl2 application lowered in-situ CH4 emissions by lowering net CH4-production, while sediment aerobic CH4-oxidation rates-as found in batch incubations of sediment from the enclosures-did not differ from control. In Fe(II)Cl2-treated sediments, a decrease in net CH4-production rates could be attributed to the stimulation of iron-dependent anaerobic CH4-oxidation (Fe-AOM). In batch incubations, anaerobic CH4-oxidation and Fe(II)-production started immediately after CH4 addition, indicating Fe-AOM, likely enabled by favorable indigenous iron cycling conditions and the present methanotroph community in the pond sediment. 16S rRNA sequencing data confirmed the presence of anaerobic CH4-oxidizing archaea and both iron-reducing and iron-oxidizing bacteria in the tested sediments. Thus, besides combatting eutrophication, Fe(II)Cl2 application can mitigate CH4 emissions by reducing microbial net CH4-production and stimulating Fe-AOM.

Fabrication of a Fe3O4/CS/AgNPs Composite from Indigenous Iron Sand for Enhanced Methylene Blue Adsorption

Fabrication of a Fe3O4/CS/AgNPs Composite from Indigenous Iron Sand for Enhanced Methylene Blue Adsorption

Microcosm Study of the Effects of pH, Reductant and Sediment Type on Uranium Immobilization

Uranium mining by in-situ recovery (ISR) involves injecting dissolved oxygen (DO) into the subsurface to oxidize and solubilize uranium minerals (e.g., uraninite), and then pumping the groundwater to the surface and removing the uranium by ion exchange. After ISR mining operations are completed, the groundwater must be restored to baseline conditions. One promising new technology for restoring groundwater at ISR sites is to inject chemical reductants that can stimulate growth of indigenous iron- and sulfate-reducing bacteria that can also reduce and immobilize uranium. Although numerous studies have validated the general feasibility of this approach, significant uncertainty remains about the effects of groundwater pH, reductant type (particularly organic versus inorganic), and sediment type (particularly pre- leaching versus post-leaching). In this study, a 23 experimental factorial design was used to assess the effects of pH, reductant type, and sediment type on uranium immobilization in 160-mL serum-bottle sediment microcosms. The experimental results showed that both reductant type and sediment type have statistically significant effects on uranium immobilization

Multi-Objective Optimization of Copper Bioleaching: Comparative Study of Pure and Co-Cultured Cultivation.

Bioleaching is a practical method to recover metals from low-grade mineral sulfides. The most frequent bacteria involved in the bioleaching of metals from ores are Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans. Experimental design is a method through which the optimum activity condition will be obtained, avoiding numerous trials and errors. This study aimed to optimize the bioleaching condition of two indigenous iron- and sulfur-oxidizing bacteria from the Meydouk mine, Iran, and evaluate their function in a semi-pilot operation in pure and mixed cultures. After treatment with sulfuric acid, the bacterial DNA was extracted, and further 16S rRNA was sequenced to characterize the bacterial species. The cultivation condition of these bacteria was optimized using Design-expert (6.1.1 version) software. The copper recovery rate and the differentiation in the ORP rate in the percolation columns were also investigated. These strains were isolated from the Meydouk mine for the first time. 16S rRNA analysis revealed that both bacteria belong to the Acidithiobacillus genus. The factors with the most significant impact on Acidithiobacillus ferrooxidans with their optimum level were temperature=35 °C, pH=2.5, and initial FeSO4 concentration=25 g.L-1. Also, initial sulfur concentration had the most significant impact on Acidithiobacillus thiooxidans with the optimum level of 35 g.L-1. Moreover, the mixed culture determined higher bioleaching efficiency compared with the case of employing the pure cultures. Utilizing a mixture of both bacteria, Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans elevated the Cu recovery rate due to the synergetic function of the strains. Also, introducing an initial dosage of sulfur and pre-acidification could elevate metal recovery efficiency.

Flaking stone activity in the tradition of iron smelting from the 8th to 17th centuries AD in the Matano region, South Sulawesi, Indonesia

Lake Matano includes a complex of sites related to an iron-smelting industry that developed at the northeast tip of South Sulawesi between the 8th and 17th centuries AD. The sites include recently discovered underwater sites which possibly submerged because of an earthquake that had occurred in the region. An interesting finding at each site is the presence of flaked artifacts from chert. This raises the question of what was the role of flaked chert in the local tradition of iron smelting. The present study was conducted by combining ethnographic data from Lake Matano and analysis of chert artifacts excavated from the Rahumpu’u lakeshore site. The results show that chert artifacts were used as strike-a-lights and in particular for the combustion of fuel for iron smelting. Flaking chert was one of the skills possessed by the Matano indigenous iron smelters in utilizing the resources in their environment to produce a high quality of iron.

Arsenic (III) Removal from Aqueous Water by Indigenous Iron Ore Adsorbent from Balochistan Province of Pakistan

The work focuses on the removal of Arsenic-III (As(III)) from water sample by an indigenous iron ore from Balochistan by adsorption method. Three iron ore samples were analyzed by X-Ray Diffractometer (XRD) and a sample from Shikarap containing iron 36.2% was selected because it contained the highest amount of hematite. The batch study was conducted to examine the adsorption by iron ore and maximum adsorption was observed at pH 6, 1/2 g dose per 50 mL solution, contact time 2 hr and shaking speed 150 rpm. At the optimized conditions, the removal was 89% when monitored at 50μg L-1 initial concentration of arsenic. The arsenic removal was monitored by Atomic Absorption Spectrometer (AAS) using hydride generation. Dubinin - Radushkevich (D-R), Freundlich and Langmuir's isotherms were examined. The highest adsorption capacityof iron ore for As(III) removal was observed 13.67 μg g-1 by Langmuir model and Freundlich isotherm indicated good adsorption intensity with value n = 1.512. Thermodynamic parameters revealed that adsorption was exothermic and physisorption. The Scanning Electron Microscope (SEM) and Energy Dispersive X-Ray (EDX)techniques were applied to scan the surface morphology and the percentage elemental composition of samples respectively. SEM results demonstrated that Shikarap mineral grains are an oval shape and these were changed after the uptake of As(III). The EDX spectra of Shikarap mineral confirm the As(III) adsorption on particles as As 4.19%.

Removal of Arsenite and Arsenate by Indigenous Iron Ores of Pakistan

This study is focusing on the comparative study of arsenite and arsenate adsorption from the water via indigenous iron ores. The Sindh and Punjab provinces of Pakistan are badly affected by Arsenic (As) toxicity as the people are consuming arsenic contaminated groundwater. The aim of this study is to investigate the effect of anions on adsorption of arsenite As(III) and arsenate As(V). Impact of pH, contact time, adsorbent dose and shaking speed on adsorption of arsenite and arsenate is studied with the two selected iron ores from Hoshi and Shikarap from Balochistan. Hoshi and Shikarap ores exhibited higher As(III) and As (V) adsorption, respectively thus selected for further removal studies. Hoshi iron ore without sodium carbonate yields higher adsorption as compared to the samples with 100 mg/L and 1000 mg/L sodium carbonate in both As(III) and As(V). Hoshi ore exhibited the highest adsorption of 85% for As (V) without sodium phosphate dibasic and 83% for As(III). Shikarap ore for As(V) adsorbs 75% without sodium phosphate dibasic and 67% adsorption for As(III) without sodium phosphate dibasic. Shikarap ore with sodium silicate at 100 mg/L adsorbs 62% As(III) and at 1000 mg/L adsorb 52% As(III). Shikarap ore As(V) adsorption decreases from 75% without sodium silicate to 70% at 100 mg/L and even lower adsorption of 65% at a higher concentration of 1000 mg/L.

NanoFe3O4 accelerates methanogenic straw degradation in paddy soil enrichments

Methanogenesis is crucial in the carbon cycle, and conductive iron oxide minerals play an important role in methanogenesis in anoxic environments. The influence of iron oxides is ubiquitous, but the strength and nature of iron oxides effects are believed to vary in response to environmental conditions, especially the soil iron concentration. We evaluated the influence of conductive nanoFe3O4 on straw degradation in high-iron (HR) and low-iron (LR) paddy soil enrichments, as well as the corresponding responses of related microorganisms. Under conductive nanoFe3O4 amendment, methane production and straw degradation increased by 184%–285% and 7.8%–12.7%, respectively, in the two soil enrichments. The increase apparently coincided with increased interspecies interactions within the microorganismal community, especially enhanced syntrophic cooperation among fermenting bacteria, syntrophic bacteria and methanogenic archaea, and facilitated interspecies electron transfer, which improved carbon conversion and alleviated end-product inhibition. The methanogenic archaeal community also exhibited changes with nanoFe3O4 amendment, and the relative abundance of Methanosarcina increased. Pairwise comparisons revealed that although methanogenic straw degradation was higher in HR soil than in LR soil, the enhancement induced by the nanoFe3O4 amendment showed to a larger degree and the microbial responses were more distinct in LR soil than in HR soil. The abundances of Geobacter and Methanosarcina greatly increased, and the microbial community shifted towards a composition similar to that in HR soil. This work indicates that iron oxides facilitate the methanogenic degradation of rice straw and that the indigenous iron content significantly influences the microbial community composition. This study provides a technique for agricultural residue degradation and has clear implications for our understanding of soil C-Fe biogeochemical coupling.

Mitigating arsenic accumulation in rice (Oryza sativa L.) from typical arsenic contaminated paddy soil of southern China using nanostructured α-MnO2: Pot experiment and field application

Manganese oxides are naturally occurring powerful oxidants and scavengers, which can control the mobility and bioavailability of arsenic (As). However, the effect of synthetic nanostructured manganese oxides on the mobilization and transportation of As at actual paddy soils are poorly understood, especially in soils with low or medium background Mn concentration. In the present study, a novel nano manganese oxide with superior reactivity and surface area has been synthesized. A 90-d soil incubation experiment combined with pot and field rice cultivation trials were designed to evaluate the effectiveness of exogenous α-MnO2 nanorods on the mobilization and transportation of As in soil-rice systems. Our results proved that the addition of α-MnO2 nanorods can effectively control the soil-to-solution partitioning of As under anaerobic conditions. After treatment with different amounts of α-MnO2 nanorods, the content of effective As decreased, offset by an increase in residual As and insoluble binding As (Ca-As and Fe-As). Enhancing the oxidation of As(III) into As(V), the α-MnO2 nanorods increased the adsorption of As onto indigenous iron (hydr)oxides which greatly reduced the soil porewater As content. In addition, pot experiments and field applications revealed that the influx of As into the aerial parts of rice plants (stems, husk and leaves) was strictly prohibited after treatments with different amount of α-MnO2 nanorods; more interestingly, significantly negative correlations have been observed between As and Mn in rice, which indicated that as Mn is increased in soil, As in brown rice decreases. Our results demonstrated that the use of α-MnO2 nanorods in As polluted paddy soil containing low levels of background Mn oxides can be a promising remediation strategy.

Xenophon in a Black Sea Landscape: Settlement Models for the Iron Age on the Sinop Promontory (Turkey)

Research into the Iron Age of Anatolia has seldom paid sufficient attention to settlement patterns and the social organization of space. TheAnabasisby Xenophon records the observations of a Greek outsider who travelled across eastern Anatolia and along the Black Sea coast in 400bce, a time that was relatively early in the colonial process in this area. Xenophon's observations are used to establish a basic model for settlement in the Black Sea coastal region of Anatolia, which is then tested against the results of recent archaeological surveys and related research on the Sinop promontory. A fuller and richer model of indigenous Iron Age settlement and colonial engagement on the Sinop promontory is developed and considered in light of recent research on colonization in the western Mediterranean and northern Black Sea regions.

Improving anaerobic fermentation of waste activated sludge using iron activated persulfate treatment

This study reported a novel and efficient approach to improve the anaerobic fermentation performance of waste activated sludge (WAS) by the indigenous iron activated persulfate (PS/Fe) treatment. Firstly, the production of short-chain fatty acids (SCFAs), especially acetic acid, was remarkably enhanced within shorter fermentation time. Mechanism investigations demonstrated that the PS/Fe treatment could simultaneously accelerate and enhance the hydrolysis and acidification process while inhibit the methanogenesis during WAS fermentation. The activities of key enzymes and the abundances of anaerobic microorganisms responsible for SCFAs production were stimulated in the presence of PS/Fe which would promote the biological processes. Secondly, the PS/Fe treatment improved the quality of fermentation residue by reducing the toxic organic compounds in the residue and enhancing the dewaterability of fermented sludge, which was beneficial to the final disposal of WAS with added economical and environmental values.

Этноархеологические исследования металлургии железа в Сибири

Этноархеологические исследования металлургии железа в Сибири

‘Are You Local?’ Indigenous Iron Age and Mobile Roman and Post-Roman Populations: Then, Now and In-Between

AbstractThe Iron Age and Roman periods are often defined against each other through the establishment of dualities, such as barbarity–civilisation, or spiritual–rational. Despite criticisms, dualities remain prevalent in the National Curriculum for schools, television, museum displays and academic research. Recent scientific studies on human origins, for example, have communicated the idea of an ‘indigenous’ Iron Age, setting this against a mobile and diverse Roman-period population. There is also evidence for citizens leveraging dualities to uphold different positions on contemporary issues of mobility, in the UK and internationally. This paper discusses values and limitations of such binary thinking, and considers how ideas of ambiguity and temporal distancing can serve to challenge attempts to use such dualities to map the past too directly onto the present, reflecting on recent social media debates about Britain and the European Union.

Role of Some Plant Growth Promotory Bacteria on Enhanced Fe Uptake of Wheat

ABSTRACTThe quest for plant growth promotory bacteria that can help in sustainable agriculture has increased in the recent years owing to increasing cost of fertilizers. In the present study, the potential of three isolated bacteria having plant growth promotory effects in mobilizing the indigenous soil iron (Fe) in two different varieties of wheat was evaluated. Three bacterial isolates belonging to the genera Burkholderia and Acinetobacter were evaluated singly and in combinations for Fe uptake of wheat in a net house study. Results showed that bacterial isolates when used in combination performed better in comparison to their individual use. These isolates significantly increased the mean Fe concentration in grains and straw by 34.0% and 52.4% over the uninoculated controls and also increased the total Fe uptake per pot in comparison to uninoculated controls. The bacterial inoculation also showed a positive impact on the bioavailability of diethylenetriaminepentaacetic acid (DTPA) extractable Fe in soil.

Evidence of arsenic mobilization mediated by an indigenous iron reducing bacterium from high arsenic groundwater aquifer in Hetao Basin of Inner Mongolia, China

A facultative anaerobic iron reducing bacterium IMCUGIR-ZA was isolated from high arsenic (As) groundwater in Hetao Basin of Inner Mongolia and was identified as Klebsiella oxytoca. Strain IMCUGIR-ZA could reduce more than 96.8% of 2.78 mmol L−1 soluble Fe(III)-citrate in 7 days and 0.42 mmol solid iron from ferrihydrite into aqueous phase in 10 days using glucose as an electron donor under strictly anaerobic conditions. Appropriate concentrations of As could improve microbially-mediated iron reduction and release from ferrihydrite. Nearly threefold iron was reduced and released by strain IMCUGIR-ZA from As(V)-doped ferrihydrite (As 100 μmol L−1). When the strain was incubated with high arsenic sediments from Hetao Basin of Inner Mongolia under anaerobic conditions, 0.894 mmol L−1 Fe(III) and 12.44 μmol L−1 As were released to aqueous phase in 7 days. The results provided evidence of microbially-mediated mobilization of As in high arsenic groundwater aquifer in Hetao Basin of Inner Mongolia, China.

A technological and anthropological study of iron production in Venda, Limpopo Province, South Africa

ABSTRACTThis study investigates the technology and sociology of indigenous iron production in Venda, northern South Africa, within a framework of ethnographies, historical documents and archaeometallurgical analyses. Investigations revealed that indigenous iron production in the study area, like elsewhere in southern Africa, was based on the direct process in which high-grade iron ores were reduced to metallic iron in charcoal fuelled low-shaft furnaces. The technology exploited at the sites under study used high-grade haematite and magnetite ores, which were extracted from open shaft mines within the vicinity of the smelting precincts. Although new furnace types appeared in the mid-second millennium AD, evidence suggests that the technology of iron smelting was relatively stable during the Early (AD 200-900) and Late (AD 1000 to 1900) Iron Ages. Iron smelting in this area was accompanied by rituals and taboos that connected the smelters to the living and the dead. A comparative study of such rituals and taboos with those invested in other categories of practice, such as male initiation, identified notable similarities and differences. This indicates that material culture production and use broadcast ideas and beliefs applicable to both technical and quotidian practices.

Interactions of the metal tolerant heterotrophic microorganisms and iron oxidizing autotrophic bacteria from sulphidic mine environment during bioleaching experiments

Iron and sulfur oxidizing chemolithoautotrophic acidophilic bacteria, such as Acidithiobacillus species, hold the dominant role in mine environments characterized by low pH values and high concentrations of reduced sulfur and iron compounds, such as ores, rocks and acid drainage waters from mines. On the other hand, heterotrophic microorganisms, especially their biofilms, from these specific niches are receiving increased attention, but their potential eco-physiological roles have not been fully understood. Biofilms are considered a threat to human health, but biofilms also have beneficial properties as they are deployed in waste recycling and bioremediation systems. We have analyzed interactions of the metal tolerant heterotrophic microorganisms in biofilms with iron oxidizing autotrophic bacteria both from the sulphidic mine environment (copper mine Bor, Serbia). High tolerance to Cu2+, Cd2+ and Cr6+ and the presence of genetic determinants for the respective metal tolerance and biofilm-forming ability was shown for indigenous heterotrophic bacteria that included strains of Staphylococcus and Rhodococcus. Two well characterized bacteria- Pseudomonas aeruginosa PAO1 (known biofilm former) and Cupriavidus metallidurans CH34 (known metal resistant representative) were also included in the study. The interaction and survivability of autotrophic iron oxidizing Acidithiobacillus bacteria and biofilms of heterotrophic bacteria during co-cultivation was revealed. Finally, the effect of heterotrophic biofilms on bioleaching process with indigenous iron oxidizing Acidithiobacillus species was shown not to be inhibitory under in vitro conditions.

Enhancing methane production from waste activated sludge using a novel indigenous iron activated peroxidation pre-treatment process

Methane production from anaerobic digestion of waste activated sludge (WAS) is limited by the slow hydrolysis rate and/or poor methane potential of WAS. This study presents a novel pre-treatment strategy based on indigenous iron (in WAS) activated peroxidation to enhance methane production from WAS. Pre-treatment of WAS for 30min at 50mg H2O2/g total solids (dry weight) and pH 2.0 (iron concentration in WAS was 7mg/g TS) substantially enhanced WAS solubilization. Biochemical methane potential tests demonstrated that methane production was improved by 10% at a digestion time of 16d after incorporating the indigenous iron activated peroxidation pre-treatment. Model-based analysis indicated that indigenous iron activated peroxidation pre-treatment improved the methane potential by 13%, whereas the hydrolysis rate was not significantly affected. The economic analysis showed that the proposed pre-treatment method can save the cost by $112,000 per year in a treatment plant with a population equivalent of 300,000.

Role of indigenous iron in improving sludge dewaterability through peroxidation.

Improvement of sludge dewaterability is important for reducing the total costs for the treatment and disposal of sludge in wastewater treatment plants. In this study, we investigate the use of hydrogen peroxide as an oxidizing reagent for the conditioning of waste activated sludge. Significant improvement to sludge dewaterability was attained after the addition of hydrogen peroxide at 30 mg/g TS and 28 mg/g TS under acidic conditions (pH = 3.0), with the highest reduction of capillary suction time being 68% and 56%, respectively, for sludge containing an iron concentration of 56 mg Fe/g TS and 25 mg Fe/g TS, respectively. The observations were due to Fenton reactions between the iron contained in sludge (indigenous iron) and hydrogen peroxide. For the sludge with an insufficient level of indigenous iron, the addition of ferrous chloride was found to be able to improve the sludge dewaterability. The results firstly indicated that indigenous iron can be utilized similarly as the externally supplied iron salt to improve sludge dewaterability through catalyzing the Fenton reactions.