Search

Heavy metal pollution is a global environmental issue, and microorganisms play a crucial role in the bioremediation of heavy metal-contaminated wastewater. The study isolated heavy metal-resistant bacterium and observed their absorption ability toward Pb2+, Cd2+ and Zn2+. We isolated Agrobacterium tumefaciens S12 from acid mine drainage. The various factors influencing its adsorption performance, including pH, biomass dosage, initial metal ion concentration, and adsorption temperature, were investigated in detail. Chemisorption controls the adsorption rate due to the results better fitted by pseudo-second order kinetics. The maximum adsorption capacities of Pb2+, Cd2+ and Zn2+ on A. tumefaciens S12 were 234, 58 and 51 mg g−1 at 30 °C from Langmuir isotherm, respectively. The adsorption processes for the three heavy metal ions were spontaneous and exothermic in nature. In bimetallic systems, biosorption of Pb2+ ions was preferential to that of Cd2+ and Zn2+. Furthermore, scanning electron microscopy coupled to energy dispersive spectroscopy, Fourier-transform infrared spectra and X-ray photoelectron spectroscopy analysis demonstrated that the adsorption mechanisms include ion-exchange, complexation interaction between the heavy metal ions and the functional groups on the surface of biomass. The obtained results indicated that A. tumefaciens S12 can be applied as an efficient biosorbent in bioremediation technology to sequestrate heavy metal ions from aqueous solution. [ABSTRACT FROM AUTHOR]

Iron and Manganese pollution were widespread in the water of northern Chinese mines, exacerbating regional water scarcity and potential ecological issues. This study aimed to remove dissolved iron and manganese from acid mine water using serpentine-loaded manganese oxide (Serp-MO) prepared by a simple coprecipitation-loaded metal method. Serp-MO was microscopically characterized, and the adsorption performance and adsorption mechanism of the Serp-MO composite adsorbent for Fe2+ and Mn2+ were analyzed. After loading, the specific surface area and pore volume of the particles significantly increased, and the surface pore structure improved, which was conducive to the simultaneous adsorption and removal of iron and manganese. The optimal reaction conditions for Serp-MO treatment of composite water samples with Fe2+ and Mn2+ mass concentrations of 20 mg/L and 5 mg/L respectively, were as follows: dosage of Serp-MO 550 mg/L, temperature 35 ℃, oscillation rate 180 r/min, and reaction time 140 min. Under these conditions, the removal rates of Fe2+ and Mn2+ were 99.8% and 99.6%, respectively. The presence of coexistence cations Zn2+ and Cu2+ can inhibit the removal of Fe2+ and Mn2+ by Serp-MO, while SO42- can promote the removal. The pseudo-second-order kinetic model and Langmuir isothermal adsorption model well described the adsorption process of Fe2+ and Mn2+ by the Serp-MO. The maximum adsorption capacities of Serp-MO for Fe2+ and Mn2+ were 14.31 mg/g and 24.04 mg/g, representing improvements of 470.12% and 626.28%, respectively, compared to Serp-MO. The adsorption thermodynamics showed that ΔG was <0 and ΔH and ΔS were greater than 0 at all test temperatures, which was an entropy-increasing reaction, and that increasing the temperature was favorable for the removal of Fe2+ and Mn2+. Based on the analysis of adsorption products, Serp-MO primarily facilitates the precipitation of iron in water, while the removal of manganese was mainly by adsorption. A regeneration study over five cycles indicated that Serp-MO possessed promising reusability potential. Furthermore, the safety leaching test indicated that the material caused minimal secondary pollution. [ABSTRACT FROM AUTHOR]

Discharge of acidic wastewater from mining activities (acid mine drainage (AMD)) is a major global environmental and public health issue. Although several approaches, including chemical precipitation and membrane technology, have been developed to treat AMD, adsorption has emerged as the most promising technology due to its cost-effectiveness and efficacy. Despite the wide adoption of adsorption in treating AMD, the evolution of research in this area remains poorly understood. To address this gap, a bibliometric analysis of the most recent literature involving the application of adsorption in AMD remediation was conducted by merging datasets of articles from Scopus (1127) and the Web of Science Core Collection (1422), over the past decade (2013–2022). This analysis revealed a yearly increase of 11% in research publications, primarily contributed by China, the United States, and South Africa. Keyword analysis revealed that natural schwertmannites and their transformations, activated carbon, zeolites, and clay minerals, are the most extensively employed adsorbents for the removal of common metals (arsenic, chromium, iron, manganese, among others). The findings underscore the need for future focuses on recovering rare earth elements, using nanoparticles and modified materials, pursuing low-cost, sustainable solutions, integrating hybrid technologies, pilot-scale studies, exploring circular economic applications of AMD sludges, and inter-continental collaborations. These insights hold significant future implications, serving as a valuable reference to stakeholders in the mining industry. [ABSTRACT FROM AUTHOR]

The insatiable demand for lithium in portable energy storage necessitates a sustainable and low-carbon approach to its recovery. Conventional hydrometallurgical and pyrometallurgical methods heavily involve hazardous chemicals and significant CO2 emissions. Herein, by integrating electrode oxidation with electrolyte oxidation, we establish a photovoltaic-driven “dual-oxidation” seawater electrolyzer system for low-carbon footprint and high lithium recovery. A 98.96% lithium leaching rate with 99.60% product purity was demonstrated for lithium recovery from spent LiFePO4 cathode materials. In-depth mechanism studies reveal that the electric field-driven electrode oxidation and in situ generated oxidative electrolyte synergetically contributes to lithium ions leaching via a structural framework elements oxidation and particle corrosion splitting synergy. This dual-oxidation mechanism facilitates rapid and efficient lithium extraction with broad universality, offering significant economic and environmental benefits. Our work showcases a promising strategy for integrating dual oxidation within a photovoltaic-driven seawater electrolyzer, paving the way for low-carbon lithium recovery from diverse solid wastes and minerals within a sustainable circular economy. [ABSTRACT FROM AUTHOR]

Chromite is formed in nature in ophiolitic layers and ultrabasic rocks through fractional crystallization. The corresponding mining technologies separate the ore from these ultrabasic rocks, which are considered to be tailings for the process but may be valorized in other applications. The need to utilize this material is due to the large quantities of its production and the special management required to avoid possible secondary pollution. In the present work, the ultrabasic rocks of chromite mining were applied to acid mine drainage (AMD) neutralization. The aim was to increase the technological maturity of the method and promote circular economy principles and sustainability in the mining sector. Ultrabasic rocks were obtained from a chromite mining facility as reference material. Furthermore, an artificial AMD solution was synthesized and applied, aiming to simulate field conditions. According to the results, the sample was successfully utilized in AMD neutralization (pH 7), achieving rapid rates in the first 30 min and maximum efficiency (liquid to solid ratio equal to 8.3) at 24 h. However, the method presented a drawback since Mg was leached, even though the concentration of other typical metals contained in an AMD solution decreased. [ABSTRACT FROM AUTHOR]

Acid mine water (AMD) can cause significant environmental hazards due to its high concentration of metal ions, so the development of effective treatment methods is essential to mitigate its impact. In this study, adsorption experiments were conducted using limestone (LS) and activated carbon (AC) to explore the adsorption efficiency for different concentrations of metal ions. Adsorption was evaluated by static and competitive batch tests. The adsorbent mechanism was investigated using analytical techniques such as SEM, FTIR and XRD. The efficacy of LS and AC for competitive adsorption of Fe, Mn, Zn and Cu ions from AMD was evaluated. The study analyzed the effect of environmental conditions such as initial concentration and ionic strength on the adsorption efficiency. The results showed that LS showed high adsorption capacity for Fe and Cu, but was less effective in competitive adsorption of Mn. AC showed superior adsorption performance for Fe and Cu under competitive conditions due to its high surface area and functional groups. Both adsorbents showed selective efficacy influenced by the physicochemical properties of metal ions. This study helps to guide the optimization of adsorbents in AMD treatment and highlights the importance of selecting suitable materials based on specific metal ion properties. [ABSTRACT FROM AUTHOR]

Mining in the Russian Far East has been developing for more than 100 years, resulting in the formation of mining technogenic systems that negatively affect all components of the environment. The purpose of this paper is to develop and present an ecological and geochemical model of supergene processes in tinsulfide and polymetallic ore mining systems. This paper presents, for the first time, the results of long-term field observations (more than 50 years): studies of numerous secondary minerals (more than 80) identified in mine workings and tailings, their natural associations, as well as the sequence, zonality, and stages of mineral formation as well as the characteristics of hydrochemical samples of river waters, contaminated by acid mine drainage (30 years of observations). Experimental modeling of sulfide oxidation was carried out under laboratory conditions (electrochemical method) and using Selektor software, which made it possible to study the process of acid mine drainage formation and to show the metal ions and ionic complexes composition, to establish Eh-pH parameters of crystallization for 52 secondary minerals, associations of primary and secondary minerals. The influence of water components on the formation of slurry and drainage in different time periods (dry, heavy rainfall, and snowmelt) is shown, and their mixing at the geochemical barrier "acid mine drainage—surface natural waters" is described. Experimental results are verified with numerous in-situ observations and mineralogical studies. The work allowed for the presentation of an environmental–geochemical model of ecosphere pollution, which describes not only the negative impact of sulfide-bearing systems of Russian Far East mining districts but locations all over the world. [ABSTRACT FROM AUTHOR]

Mitigating acid mine drainage (AMD) at its source, specifically within rocks containing pyrite in underwater environments, poses a significant environmental challenge worldwide. Existing passivation techniques are primarily designed for open-air conditions, involving direct contact with coating materials at a solid–liquid interface, making them ineffective beneath a water barrier. In this study, we introduce a novel passivation method inspired by the design of underwater bio-adhesives. Tannic acid (TA) combined with polyethylene glycol (PEG) was employed to form a hydrophobic film directly on the pyrite surface, overcoming water resistance and addressing the limitations of current techniques. Electrochemical experiments and chemical leaching experiments were conducted to evaluate the oxidation resistance of the passivating films. TA–PEG-coated pyrite exhibited a lower oxidation rate and a higher static contact angle of 126.2°, achieving suppression efficiencies of 71.6% for total Fe release and 68.1% for total S release. A comprehensive characterization approach, including scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS), was employed to investigate the passivation mechanism. The results of this study may provide new insights into the preparation of simpler and greener passivating agents to suppress pyrite oxidation at its source in underwater environments. [ABSTRACT FROM AUTHOR]

Acid mine drainage (AMD) pollutes natural waters, but some impacted systems show natural attenuation. We sought to identify the biogeochemical mechanisms responsible for the natural attenuation of AMD. We hypothesized that biogenic sulfide-mediated iron reduction is one mechanism and tested this in an experimental model system. We found sulfate reduction occurred under acidic conditions and identified a suite of sulfate-reducing bacteria (SRB) belonging to the groups Desulfotomaculum, Desulfobacter, Desulfovibrio, and Desulfobulbus. Iron reduction was not detected in microcosms when iron-reducing bacteria or SRB were selectively inhibited. SRB also did not reduce iron enzymatically. Rather, the biogenic sulfide produced by SRB was found to be responsible for the reduction of iron at low pH. Addition of organic substrates and nutrients stimulated iron reduction and increased the pH. X-ray diffraction and an electron microprobe analysis revealed that the polycrystalline, black precipitate from SRB bioactive samples exhibited a greater diversity of iron chalcogenide minerals with reduced iron oxidation states, and minerals incorporating multiple metals compared to abiotic controls. The implication of this study is that iron reduction mediated by biogenic sulfide may be more significant than previously thought in acidic environments. This study not only describes an additional mechanism by which SRB attenuate AMD, which has practical implications for AMD-impacted sites, but also provides a link between the biogeochemical cycling of iron and sulfur. [ABSTRACT FROM AUTHOR]

Acidophilic sulphate‐reducing bacteria (aSRB) are widespread anaerobic microorganisms that perform dissimilatory sulphate reduction and have key adaptations to tolerate acidic environments (pH <5.0), such as proton impermeability and Donnan potential. This diverse prokaryotic group is of interest from physiological, ecological, and applicational viewpoints. In this review, we summarize the interactions between aSRB and other microbial guilds, such as syntrophy, and their roles in the biogeochemical cycling of sulphur, iron, carbon, and other elements. We discuss the biotechnological applications of aSRB in treating acid mine drainage (AMD, pH <3), focusing on their ability to produce biogenic sulphide and precipitate metals, particularly in the context of utilizing microbial consortia instead of pure isolates. Metal sulphide nanoparticles recovered after AMD treatment have multiple potential technological uses, including in electronics and biomedicine, contributing to a cost‐effective circular economy. The products of aSRB metabolisms, such as biominerals and isotopes, could also serve as biosignatures to understand ancient and extant microbial life in the universe. Overall, aSRB are active components of the sulphur and carbon cycles under acidic conditions, with potential natural and technological implications for the world around us. [ABSTRACT FROM AUTHOR]

Copyright of Gold (1001-1277) is the property of Gold Magazine Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

BACKGROUND: This work studied the treatment of a synthetic sphalerite acid mine drainage (AMD). The treatment was carried out by means of a previous concentration stage using electrodialysis, followed by electrodeposition using a bioelectrochemical system (BES). RESULTS: The best concentration results were obtained when operating the electrodialysis at 8 V and at a diluate/concentrate volume ratio of 3. This treatment yielded a concentrate fraction of about 25% of the volume and a clear fraction of about 75% of the volume. The concentrated fraction was treated in a BES for the electrodeposition of the metal contained. By operating a microbial fuel cell (MFC), the spontaneous reactions took place and, in 2 days, all the Fe3+ was reduced to Fe2+; then, all the Cu2+ was electrodeposited as pure Cu0 in about 8 days. The maximum current density attained in this stage was 0.1 mA cm−2 and the maximum power was 0.05 W cm−2. Then, a subsequent operation of a microbial electrolysis cell (MEC) allowed for the simultaneous recovery of the Fe2+, Ni2+, Zn2+, and Cd2+ as a mixed metal mass. CONCLUSION: The electrodialysis yielded a clear effluent representing 75% of the total volume and a concentrated effluent accounting for 25%. It was possible to treat the concentrated effluent in an MFC, recovering pure Cu0 with a net electricity generation. The non‐spontaneous metal reductions were subsequently accomplished by means of MEC, the electricity requirements being lower than those in the case of the raw AMD due to the higher mass transfer rate and the reduction of the Ohmic loses. © 2023 Society of Chemical Industry (SCI). [ABSTRACT FROM AUTHOR]

The mining production industry often leaves large quantities of mine spoil heaps exposed on the surface. The lack of monitoring of these discharges could create sources of pollution; the most common among them is acid mine drainage, which causes the contamination of the environment by heavy metals present in its solutions. Bouaazza’s mine, present in Taza province North-East Morocco, was known for lead and sulfide exploitation for many years, which contributed to the exposure of important quantities of acid spoil heaps on the surface. To assess the impact caused by acid mine drainage in Makhat’s stream plants, sediments, and plant samples were collected along the stream. Physicochemical results for sediments showed pH values below 6. Geochemical results for sediments indicated Pb concentrations higher than the World Surface Rock Average standards (16 ppm), with values over 3000 ppm. As for plants, the values found after ICP-AES analyses were higher than the WHO permissible limit (2 ppm). These results confirm the harmful impact of the lack of environmental monitoring while and after abandoning mining explorations, which leads to environmental disasters. [ABSTRACT FROM AUTHOR]

The Lorraine mine site in Témiscamingue region (Québec, Canada) was reclaimed with a cover with capillary barrier effects (CCBE) to limit acid mine drainage generation. The main objective of this study is to predict the long-term hydrogeological behaviour of the CCBE at Lorraine site, including the influence of vegetation and climate change (CC). Numerical simulations showed that performance of the CCBE is: (1) not affected by forest vegetation and CC in the saturated zone in the north of the Lorraine site and (2) more sensitive to vegetation in the unsaturated zone in the south where the phreatic level is low. [ABSTRACT FROM AUTHOR]

Acid mine drainage (AMD) is an environmental concern, and its discharge into the surrounding environment can lead to acidification of water bodies and soil. In this research, red mud (RM) with alkaline pH as aluminum industry waste was implemented as an adsorbent for sulfate removal, which can be available in AMD and adsorption processes as an influential method was applied for AMD treating. Seawater washing (BRM), acid treatment (HRM), and composition with chitosan (CRM) were employed as RM modification methods. Various analytical methods were applied, including x-ray fluorescence spectroscopy (XRF), Fourier-transform infrared spectroscopy (FTIR), Brunauer Emmett Teller (BET), inductively coupled plasma analysis, and zeta potential, to have a clear comprehension of the sulfate adsorption behaviors and performance of activated methods. These methods have had desirable effects on the sulfate adsorption and adsorption amount, which range from 1.1 mg g−1 for RM reached to 13.4, 39.7, and 67.4 mg g−1 for BRM, HRM, and CRM, respectively. XRF results demonstrated a decrease in calcium and sodium ion amounts that can occur due to their dissolution in the acidic solution. It can create the active surface areas for adsorption onto RM with acid washing. Based on FTIR results, sharp intensity vibration was observed in BRM, HRM, and CRM after sulfate adsorption in the 1,100 cm−1 band that is approximately related to SO42− vibration. BRM porosity decreased from 0.0686 to 0.0345 cm3 g−1 due to various salts' precipitation in seawater, but the porosity volume and specific surface area increased for HRM from 0.0686 to 0.184 cm3 g−1 due to dissolution of ions in HCl. In addition, zeta potential increased to positive amounts from 2.7 to 3.4, 3.8, and 4.5 mv for BRM, HRM, and CRM, respectively. Langmuir isotherm indicated that the highest adsorption amount (qm) as a calculated parameter for BRM, HRM, and CRM was 0.88, 2.45, and 18.6 mg g−1 , respectively. Among modification methods, combination RM and chitosan had the highest impact and increases sulfate removal and adsorption amount at lower pH levels due to further positive charge on the CRM surface. [ABSTRACT FROM AUTHOR]

Bioremediation of acid mine drainage (AMD) was often challenged by poor tolerance of sulfate-reducing bacteria (SRB) to heavy metals and low bioactivity. The highly active immobilized particles with Fe0/Fe2+ enhanced SRB (Fe0/2+-SRB) were prepared by the microorganism immobilization technique. Three dynamic columns were constructed to investigate the adsorption capacity of Fe0/2+-SRB for Mn2+ under varying adsorption layer heights, inflow velocity, and initial Mn2+ concentrations. The role of each matrix material in the immobilized particles was explored, the mechanism of AMD remediation by Fe0/2+-SRB was revealed, and the adaptability of Fe0/2+-SRB to AMD under various initial conditions was investigated. The results showed that the prepared Fe0/2+-SRB exhibited a well-developed surface pore structure. When the adsorption layer height was 200 mm, the influent flow rate was 5 × 10−5 m3/s, and the initial manganese ion concentration was 10 mg/L, the maximum dynamic adsorption capacities (qe) of Mn2+ for each dynamic column were 7.8430, 4.7627, and 8.7677 mg/g, respectively. Compared to dynamic columns 1# and 2#, dynamic column 3# showed the best performance in treating AMD, and the Thomas model effectively described the adsorption kinetics of Mn2+ by Fe0/2+-SRB(3#). Microstructural analysis indicated that chemical adsorption, ion exchange, dissimilation–reduction reaction, and surface complexation occurred between the various matrix materials in Fe0/2+-SRB(3#). Mn2+ was primarily removed in the form of metal sulfide (MnS), and Fe0/Fe2+ could promote the dissimilatory reduction of SO42− by SRB to form S2−. Fe0/2+-SRB(3#) was able to adapt to AMD with initial conditions of pH was 2~4, SO42− < 2500 mg/L, and Mn2+ < 20 mg/L. The research results provide new insights into the remediation of AMD, using a combined microbial-adsorption technology. [ABSTRACT FROM AUTHOR]

Cadmium is a toxic heavy metal found in acid mine drainage. It hinders plant and animal growth and accumulates in human organs. In this study, through shake flask experiments, an iron-rich, sulphate-rich environment was simulated, and Acidithiobacillus ferrooxidans was used to mediate the formation of secondary high-iron minerals to explore the effect of calcium ions on the removal of Cd2+ from that environment. Four treatment systems were used: "Blank", "Ca2+-30 mg/L", "Fe/K = 3,Ca2+-30 mg/L", and "Fe/K = 3". The results showed that Cd2+ with an initial concentration of 20 mg/L was effectively removed in each treatment system. The removal efficiencies of Cd2+ in each treatment were 23.46%, 18.42%, 52.88%, and 45.76% respectively. The quantity and type of minerals determined the removal efficiency of Cd2+. The Fe/K = 3 treatment system can significantly increase the amount of mineral formation and improve the removal efficiency of Cd2+. In the Ca2+-30 mg/L, Fe/K = 3 treatment system, the biological oxidation ability was the strongest, and the removal effect of Cd2+ was the best under the combined action of K+ and Ca2+. Co-precipitation was the main way to remove Cd2+ during the formation of biogenic secondary iron minerals, and the removal amount was 5.64 to 14.83 times that of adsorption. Biogenetic secondary iron minerals showed high values in repairing heavy metal pollution. This study provides a theoretical basis for treating heavy metals in acid mine drainage. [ABSTRACT FROM AUTHOR]

Stockpiles containing sulfide minerals are subject to oxidation reactions when exposed to atmospheric conditions, which can result in the formation of acid mine drainage (AMD). Reactive waste rock has limited re-use potential due to the contamination risk associated with the generated drainage water. The re-use of reactive waste rock could lead to a significant reduction in the volume of waste rock as it mitigates the environmental impact of mine waste deposition. Acid mine drainage generation rate depends on sulfide weathering kinetics which are controlled by many parameters such as the mineralogy and the particle size. Fine fractions of waste rock have higher specific surface areas and degree of liberation of sulfides, resulting in greater reactivity than the coarse fractions. The objective of this research was therefore to evaluate the potential of re-use by controlling particle size using the sieving method. Two different potentially acid-generating waste rocks were divided into six fractions and subjected to both static and kinetic tests. Prediction of the geochemical behavior using static test did not consider the liberation of the minerals, and the long-term prediction was therefore overestimated. Results of the kinetic columns showed there was less oxidation of the sulfide minerals in the coarse fractions than in the fine fractions. Additionally, the distribution of sulfidic minerals and neutralizing minerals with particle size is influencing the potential of the re-use of the reactive waste rock. [ABSTRACT FROM AUTHOR]

Elevated concentrations of contaminants have negative impacts on aquatic organisms and their parasites. Changes in parasite infections have been proposed as a technique for monitoring the health of aquatic ecosystems. Furthermore, alterations in physiological responses (biomarkers) of organisms have also been used to delineate ecosystem quality. Lake Heritage is situated along the Crocodile River in Muldersdrift, Gauteng, South Africa, and is subject to contamination by acid mine drainage. Clarias gariepinus is a well‐studied bioindicator species and host to numerous endoparasites and ectoparasites. The aims of this study were to delineate the health status of Lake Heritage through a multifaceted approach by comparing the water quality, biomarker responses, and parasite biodiversity of C. gariepinus, compared to unexposed laboratory‐reared fish. Physical and chemical water quality parameters were determined using a hand‐held probe, test kits, and element analysis with inductively coupled plasma‐mass spectrometry. Biomarker responses in the gill, liver, and muscle tissues from C. gariepinus were assessed for total protein, metallothioneins, superoxide dismutase (SOD), and reduced glutathione (GSH) concentrations and activities of acetylcholinesterase and catalase. Results for water quality variables showed higher pH, nitrate, hardness, and copper levels compared with the South African Target Water Quality Guidelines. Catalase activity and concentrations of SOD and reduced GSH showed a response in C. gariepinus to the water quality. Ectoparasites had lower prevalence and mean intensity than endoparasites. However, there were no differences in the physiological responses between infected and uninfected hosts. The study shows that the eutrophic conditions in Lake Heritage cause biomarker responses in the host when compared to host fish in laboratory conditions. Integr Environ Assess Manag 2024;20:1539–1553. © 2023 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC). Key Points: The water quality in this river is impacted by acid mine drainage (AMD), sporadic treatment of AMD, point‐source pollution, and runoff.Inhibition of acetylcholine esterase activity in Clarias gariepinus implies that organophosphate and carbamates are also entering the system, and the lake is eutrophic.Ectoparasite infection intensity, number, and diversity are reduced, while endoparasite numbers and diversity are higher.Water quality has a greater impact on the physiological response of the host, compared to the effect caused by the endoparasites or ectoparasites. [ABSTRACT FROM AUTHOR]

Copyright of Mine Water & the Environment is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This review critically examines the effects of AMD from the gold mines of South Africa and available options. We also critically analyse case studies, research gaps, and the challenges and opportunities presented by the AMD. Our assessment indicates the availability of potential technological advancements that might flip the paradigm in favour of less sludge being produced, lower operational costs, and more effective AMD treatment strategies. This has led to the development of long-term plans for AMD treatment technologies and the recovery of important minerals. There is currently a demand for integrated AMD technologies that take a holistic approach to long-term AMD treatment. Reusing water and recovering valuable resources like sulphuric acid, rare earth elements, and other metals have received a lot of attention. Continued study and implementation of such strategies will support sustainable gold mining, address the environmental damage caused by AMD, and optimize resource and revenue-generating potentials. [ABSTRACT FROM AUTHOR]

Copyright of Mine Water & the Environment is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Environmental desulfurization was investigated as a potential tailings management method in the development of a new orebody. The operators expected variability in the geochemical and mineralogical properties of the minerals within the orebody, therefore a study based on geometallurgy principles was adapted for environmental risk prevention purposes. The objective was to evaluate the variability in the performance of environmental desulfurization by bulk sulphide flotation to produce non-acid generating tailings. The study was performed on 18 drill core samples collected from different zones of the orebody. Physical, chemical, environmental and mineralogical characterizations were done on these 18 ore samples, which were then fed to the desulfurization process. Desulfurization by froth flotation yielded a sulphide concentrate and desulfurized tailings. Similar characterization was performed on these products. The desulfurized tailings were then separated into three groups according to their acid generation potential computed from acid base accounting. Kinetic column tests were performed on six samples, two potentially acid generating, two non-acid generating, and two uncertain, and led to a better classification in acid generation potential, with only one sample confirmed acid generating. The study demonstrated that a detailed characterization of different zones of an orebody is important to identify variability in geochemical and mineralogical properties and their effect on the performance of environmental desulfurization for acid mine drainage prevention. [ABSTRACT FROM AUTHOR]

The growing demand for valuable metals in recent decades has heightened the economic significance of extracting them from dilute solutions. This research carefully assesses the extraction efficiency of the air-assisted solvent extraction (AASX) process for effectively recovering copper from industrial dilute solutions, such as the raffinate of the solvent extraction (SX) plant and heap leach solutions. The results clearly showed that increasing the frother dosage to 50 mg/L improved the Cu extraction from 83.5% to 90.2%, but increasing the frother dosage beyond 50 mg/L did not change this response significantly. Although varying the extractant concentration and silicone oil dosage in the studied range did not affect Cu extraction, it noticeably led to an increase in the barrier metals recovery. Furthermore, a nine-step AASX system was applied to comprehensively evaluate the extraction efficiency of Cu from dilute heap leach solution. Moreover, an impressive 95.1% of Cu recovery (from a solution containing 890 mg/L Cu, 12.32 g/L Fe, 2.64 g/L Zn, and 4.1 g/L Mn) was achieved with selectivity ratios of 149.6, 153.0, and 93.5, for Cu/Fe, Cu/Zn, Cu/Mn, respectively. It could be concluded that the AASX process is an efficient and promising method for extracting Cu from industrial dilute solutions derived from secondary resources, low-grade ores, and acid mine drainages. [ABSTRACT FROM AUTHOR]

This study investigated the Zaalklapspruit valley bottom wetland in South Africa, an ecologically engineered site influenced by acid mine drainage (AMD) from a defunct coal mine upstream. Conducted in 2022, the research aimed to elucidate the dynamics of contaminant dispersal within this wetland, focusing on the sources, pathways, and receptors of metals and sulfur compounds. The analysis revealed that the wetland's bottom sediment is rich in organic material, with pH values ranging from 6.05 to 6.59 and low oxidation-reduction potentials reaching −219.67 mV at Site S3. The significant findings included the highest adsorption rates of manganese, contrasted with iron, which was primarily absorbed by the roots of Typha capensis and the algae Klebsormidium acidophilum. The macrophyte rhizospheres were found to host diverse microbiota, including families such as Helicobacteraceae and Hydrogenophilaceae, pivotal in metal and sulfur processing. This study highlighted the complex biogeochemical interactions involving sediment, macrophyte root systems, periphyton, and microbial populations. These interactions demonstrate the efficacy of ecologically engineered wetlands in mitigating the impacts of acid mine drainage, underscoring their potential for environmental remediation. Importantly, the sustainability of such interventions highlights the need for community involvement and acceptance, acknowledging that local support is essential for the long-term success of ecological engineering solutions that address environmental challenges like AMD. [ABSTRACT FROM AUTHOR]

Critical minerals (CMs) are pivotal in modern industries, such as telecommunications, defense, medicine, and aerospace, contributing significantly to regional and global economic growth. However, the reliance on external sources for 26 out of 50 identified CMs raises concerns about supply chain vulnerabilities. To address this, the research focused on developing a hydrometallurgical process for extracting cobalt, manganese, and nickel from acid mine drainage (AMD) treatment by-products, emphasizing the need to diversify CM supply chains within the United States (US). A solution composed of an REE solvent extraction raffinate loaded with cobalt, manganese, nickel, and various impurity metals was utilized as a feedstock in this study. The developed hydrometallurgical process involved initial sodium hydroxide precipitation to remove impurities like aluminum and iron from an SX raffinate solution generated during the extraction of rare earth elements (REEs). Precipitation stages were performed in a pH region ranging from 2 to 12 to identify the optimum pH values, achieving a tradeoff between recovery and impurity removal. A subsequent precipitation process at pH 5–10 yielded a product rich in CMs, such as manganese, cobalt, and nickel. Further separation steps involved nitric acid washing, resulting in a Mn product with a purity of 47.9% by weight and a solution with extractable concentrations of cobalt and nickel. Stagewise precipitation with sodium sulfide subsequently produced three solid products: cobalt and nickel product at pH 1–5, manganese product at pH 5–10, and magnesium at pH 10–12. The study also explored other separation approaches, including solvent extraction, to enhance the separation of nickel from cobalt. Overall, the developed hydrometallurgical process generated the following products with varying degrees of purities: cobalt (9.92 wt.%), nickel (14 wt.%), manganese (47.9 wt.%), and magnesium (27.49 wt.%). This research aimed to contribute to the sustainable extraction of CMs from secondary sources, reducing the US' reliance on imports and promoting a more resilient supply chain for these crucial elements. [ABSTRACT FROM AUTHOR]

Sulphate ions removal from Acid mine drainage (AMD) is crucial to mitigate its adverse impact on aquatic and terrestrial ecosystem. Similarly, surplus and unused quantity of the Fly ash, waste from coal-based power plants is also challenging problem. In the present study, Fly ash based low-cost adsorbents (NaOH at 100 oC and HCL at 400 oC) activated Fly ash were synthesized using thermal activation methods. The composition and surface morphology studies were conducted using FTIR, XRD, XRF and SEM-EDX analysis. The Synthesized adsorbents were used to removal of sulphatic ion under various experimental conditions such as initial concentration (5 to 50 mg L−1), contact time (0 to 180 minutes), dose (5 to 40 mg L−1), solution pH (4.5, 5 and 5.5 pH). The optimum removal was 63 ± 1.4 % and 65 ± 1.6 % at room temperature 27 °C, pH 5.5 and 0.6 g L−1 dose of FAZ-HCl and FAZ-NaOH adsorbents respectively. The kinetics models and adsorption isotherm were determined to be pseudo second order (R2 > 0.9919) for FAZ-HCl and pseudo first order which (R2 > 0.9857) was validated and fitted by Freundlich isotherm (R2 > 0.9806 and 0.9932) for FAZ-HCl and FAZ-NaOH. [ABSTRACT FROM AUTHOR]

This paper addresses the challenge of remediating soil impacted by acid mine drainage (AMD) using an innovative and sustainable Technosol‐based approach to stabilize soil and facilitate vegetation recovery. The study assessed the effectiveness of Technosols made from recycled organic (water clarification sludge) and inorganic (siderurgical slags and red gypsum) wastes in mitigating the detrimental effects of AMD on soil properties, pore water chemistry, and plant growth through a 4‐month pot experiment. Technosols significantly improved soil health by neutralizing net acidity (296 mmol H+ kg−1), raising pH levels from extremely acidic (3.3) to mildly alkaline (7.7–8.0), and limiting the mobility of potentially toxic elements (PTEs). Dissolved Cu and Zn concentrations dropped from 80.21 and 72.08 mg L−1, respectively, to below 1 mg L−1 by the end of the monitoring period. The experiment identified several concomitant mechanisms of PTE retention, such as decreased dissolution of metal‐bearing minerals, precipitation reactions and adsorption onto Fe and Al (oxy)hydroxides. Aqueous speciation modelling indicated a decline in toxic metal forms (e.g. Al3+, AlSO4+, Cu2+, Zn2+ and H2AsO4−) in soil pore water after treatment, thus reducing phytotoxicity. Additionally, waste amendments enhanced nutrient availability, with nitrate concentrations reaching up to 417 mg L−1, supporting seed germination and seedling establishment. The most effective Technosol, combining water treatment sludge and white steel slag (60:40 w/w), enabled robust growth of Brassica juncea. Principal component analysis showed a strong correlation between healthy plant responses (survival rate, plant height, leaf number, biomass production) and improved soil pore water parameters (pH, PTEs, aluminium, calcium, bicarbonate and nitrate ions), highlighting the benefits of waste amendments. These findings underscore the potential of waste‐derived Technosols in stabilizing AMD‐impacted soils and promoting thriving plant growth. However, further validation in field trials with diverse plant species is recommended for real‐world applications. [ABSTRACT FROM AUTHOR]

Wetlands are critical ecological infrastructures that improve water quality, serve as habitat for fish and other aquatic life, accumulate floodwaters, and maintain surface water flow during dry periods. However, the health of wetlands has been compromised by anthropogenic activities that affect the constant supply of ecosystem services. This study assessed the impact of anthropogenically modified land use on wetland health in the Witbank Dam Catchment in South Africa, whose land use has been severely modified for agriculture and mining purposes. The study developed a model linking surface runoff generated in the catchment with land use and wetland typology to comprehend diffuse pollution from pollution-source land uses. Runoff data and related wetland spatial information were processed and analysed in a Geographic Information System (GIS) to estimate pollutants (agricultural nutrients and acid mine drainage) from runoff detained and released by wetlands. The analysis facilitated the assessment of the value of wetlands in enhancing water quality, as well as human and environmental health. The runoff volume from pollution-source land uses (urban areas, farmlands, and mining) was used to evaluate annual pollution levels. Wetland types are ranked according to their efficiency levels to filter pollutants. The assumption is that the difference between filtered and unfiltered runoff is the quantity of polluted runoff water discharged into the river system. The analysis has shown that 85% of polluted runoff generated in the catchment ends up in the river system. An important observation is that although wetlands have a substantial ability to absorb excess pollutants, they have finite boundaries. Once they reach their full holding capacity, they can no longer absorb any further pollutants. The excess is discharged into the river system, risking human and environmental health. This explains why the Limpopo River is heavily polluted resulting in the death of fish, crocodiles and other aquatic life. [ABSTRACT FROM AUTHOR]

Acid mine drainage (AMD), containing large quantities of heavy metals and acidic components, poses a severe threat to the environment and human health. Acidithiobacillus ferrooxidans (A. ferrooxidans) plays a crucial role in the treatment of AMD, but its activity is significantly influenced by environmental conditions. This study systematically analyzes the stress effect of high phosphorus concentration on A. ferrooxidans during AMD treatment and its biomineralization effect. The results indicate that with phosphorus concentrations ranging from 0 g/L to 2 g/L, the system's pH and Fe2+ oxidation rate initially decrease and then increase, with higher phosphorus concentrations delaying the time of increase. When the phosphorus concentration exceeds 2 g/L, both pH and Fe2+ oxidation rates generally show a downward trend. The morphology and elemental composition of the precipitates obtained under different phosphorus concentrations exhibit significant differences, indicating that phosphorus concentration notably affects the oxidation activity of A. ferrooxidans and its mediated biomineralization process. Under high phosphorus concentrations, the activity of A. ferrooxidans is inhibited, hindering the Fe2+ oxidation process and resulting in the formation of a large quantity of amorphous ferric phosphate precipitates. The findings provide a scientific basis for optimizing AMD treatment technologies, suggesting that reasonable control of phosphorus concentration in practical applications can improve AMD treatment efficiency and pretreatment effects. [ABSTRACT FROM AUTHOR]

The successful adoption and widespread implementation of innovative acid mine drainage treatment and resource recovery methods hinge on their capacity to demonstrate enhanced performance, economic viability, and environmental sustainability compared to conventional approaches. Here, an evaluation of the efficacy of chromium-based metal–organic frameworks and amine-grafted SBA15 materials in adsorbing europium (Eu) from actual mining wastewater was conducted. The adsorbents underwent comprehensive characterization and examination for their affinity for Eu. Cr-MIL-PMIDA and SBA15-NH-PMIDA had a highest Langmuir adsorption capacity of 69 mg/g and 86 mg/g, respectively, for an optimum level of pH 4.8. Preferential adsorption tests followed using real AMD collected at a disused mine in the north of Norway. A comparative study utilizing pH-adjusted real AMD revealed that Cr-MIL-PMIDA (88%) exhibited slightly higher selectivity towards Eu compared to SBA15-NH-PMIDA (81%) in real mining wastewater. While Cr-MIL-PMIDA displays excellent properties for the selective recovery of REEs, practical challenges related to production costs and potential susceptibility to chromium leaching make it less appealing for widespread applications. A cost–benefit analysis was then undertaken to quantify the advantages of employing SBA15-NH-PMIDA material. The study disclosed that 193.2 g of EuCl3 with 99% purity can be recovered by treating 1000 m3 of AMD. [ABSTRACT FROM AUTHOR]

The prolonged impact over the Tinto River estuary by both the significant pollution by acid mine drainage (AMD) affecting this river and the polluted releases from phosphogypsum (PG) piles has led to the severe environmental degradation of this ecosystem. The aim of this work was to assess the current environmental quality of the Tinto River estuary through the study of the spatial distribution of metal(loid)s and natural radionuclides in the surface sediments from the channel edge. The sediments contain mean concentrations 5–20 times higher than the background values for pollutants such as Zn, As, Cu, Pb, or U, and up to two orders of magnitude higher for P. The studied sediments are heavily polluted by toxic heavy metals and metalloids (Pb, Zn, Cu, and As) according to the US EPA guidelines. Most of the analyzed sediment samples are also strongly polluted by long-lived natural radionuclides, mainly U-isotopes and 210Pb with concentrations up to one order of magnitude higher than unpolluted sediments, mostly due to the contribution by the PG leachates. The enrichment factors (EF) were extremely high (EF > 50) for As and very severe enrichment (25 ≤ EF < 50) for P, Cd, Zn, Cu, and Pb. [ABSTRACT FROM AUTHOR]

This article discusses the challenges and importance of accurately annotating transporters in metabolic modeling. It emphasizes the need for investment in accurate functional characterization to improve predictive tools and benefit fields such as personalized medicine, metabolic engineering, and microbial ecology. The text also discusses the types of errors that can occur in transporter annotations and the databases and tools available for transporter annotation. The document is a list of references to various scientific articles and databases related to protein subcellular localization, phenotypic testing, gene function, transporter systems, metabolic modeling, and microbial communities. These resources provide valuable information for researchers studying these areas of biology and can be used as references for further exploration. [Extracted from the article]

From an engineering standpoint, investigating the effects of rotation speed and fulvic acid concentration on the development of secondary high-iron minerals is crucial for treating acid mine drainage. The Fe2+ oxidation mechanism by Acidithiobacillus (A.) ferrooxidans to synthesise secondary high-iron minerals was examined in this study using shaking flask tests under various conditions: fulvic acid concentrations of 0, 0.2, or 0.4 g/L and rotation speeds of 180 r/min or 100 r/min. The pH, Fe2+ oxidation rate, total iron precipitation rate, secondary high-iron mineral functional groups and ore equivalent indicators were also investigated. The results demonstrated that at a fulvic acid concentration of 0 g/L, the pH decreased from 2.5 to 2.17 at 180 r/min. At 0.2 g/L, it decreased from 2.5 to 2.05. Finally, at 0.4 g/L, it decreased from 2.5 to 2.07. Fe2+ was completely oxidised after 48 h, and the final total iron precipitation rate ranged from 26.2% to 33.4%. The synthesised secondary high-iron minerals were uniformly dispersed in the solution. When the rotation speed was 100 r/min, the pH reduced from 2.5 to 2.25 at a fulvic acid concentration of 0 g/L, from 2.5 to 2.14 at 0.2 g/L, and from 2.5 to 2.19 at 0.4 g/L. Notably, Fe2+ was completely oxidised within 72 h. The experiment's final iron precipitation rate ranged from 23.6 to 29.6%. The synthesised secondary high-iron minerals were blocky and adhered to the bottom of the shaking flask. In summary, at a rotation speed of 180 r/min or 100 r/min, the Fe2+ oxidation rate and total iron precipitation rate of the experimental group with a fulvic acid concentration of 0.2 g/L were higher than those of the control group and the experimental group with a fulvic acid concentration of 0.4 g/L. A fulvic acid concentration of 0.2 g/L enhanced the activity of A. ferrooxidans. The minerals obtained from these experiments were characterised and identified as schwertmannite and jarosite. [ABSTRACT FROM AUTHOR]

Acid mine drainage (AMD) is one of the main environmental problems associated with mining activity, whether the mine is operational or abandoned. In this work, several precipitates from this mine drainage generated by the oxidation of sulfide minerals, when exposed to weathering, were used as adsorbents. Such AMD precipitates from abandoned Portuguese mines (AGO, AGO-1, CF, and V9) were compared with two raw materials from Morocco (ClayMA and pyrophyllite) in terms of their efficiency in wastewater treatment. Different analytical techniques, such as XRD diffraction (XRD), Fourier Transform Infrared spectroscopy (FTIR), N2 adsorption isotherms, and Scanning Electron Microscopy (SEM) with Energy Dispersive X-ray (EDX) were used to characterize these natural materials. The adsorption properties were studied by optimizing different experimental factors, such as type of adsorbent, adsorbent mass, and dye concentration by the Box–Behnken Design model, using methylene blue (MB) and crystal violet (CV) compounds as organic pollutants. The obtained kinetic data were examined using the pseudo-first and pseudo-second order equations, and the equilibrium adsorption data were studied using the Freundlich and Langmuir models. The adsorption behavior of the different adsorbents was perfectly fitted by the pseudo-second order kinetic model and the Langmuir isotherm. The most efficient adsorbent for both dyes was AGO-1 due to the presence of the cellulose molecules, with qm equal to 40.5 and 16.0 mg/g for CV and MB, respectively. This study confirms the possibility of employing AMD precipitates to adsorb organic pollutants in water, providing valuable information for developing future affordable solutions to reduce the wastes associated with mining activity. [ABSTRACT FROM AUTHOR]

The performance of reclamation cover systems could be affected by the colonization of plant roots, which may modify the hydrogeological properties of the construction materials. A four-year field investigation was conducted using six experimental cells with various soil layering designs over AMD-generating tailings reclaimed with an oxygen-barrier cover combined with an elevated water table. Both herbaceous and woody vegetation were installed on top of the cells to compare the influence on the properties of the cover material. Consecutive and undisturbed cores were collected from the cover's functional layer in 2020 and 2021, respectively. Root parameters, such as root length density, and hydrogeological properties were measured on the core samples to assess the possible relationships between the two categories of variables. Root observation trenches were also cut in each cell to better analyze the root density and occurrence profiles. Results showed that, within the four-year monitoring period of the study, both herbaceous and woody vegetation roots mostly colonized the top overburden layer of the cell (>86% visible roots) and barely occupied the functional layer of the reclamation cover (<10% visible roots). The observed maximum desorption rates for the functional layer were lower than the predicted values, which could be a short-term effect of the fine roots. No significant impact of roots on the main hydrogeological variables controlling the oxygen barrier efficiency were noted. At the end of the four-year study period, the hydrogeological behavior of the functional layer in all cells with/without vegetation/additional soil layers was found to be similar. [ABSTRACT FROM AUTHOR]

The objective of this study was to assess the water quality status of the surface water and groundwater resources in the Middelburg area, South Africa. The assessment was addressed using combined water quality indices, investigating selected chemical parameters over four different seasons for a period of five years from 2017 to 2021. A combination of the Canadian Council of Ministers of the Environment water quality index and the comprehensive pollution index was used to analyze the water quality status of surface water and groundwater of the town of Middelburg, situated near coal mining activities in Mpumalanga, South Africa. The combination of the indices indicated that some surface water monitoring sites ranged between poor to fair water quality. Groundwater monitoring points also showed a poor to fair ranking. The comprehensive pollution index confirmed that some sites showed very poor water quality in the summer seasons, exceeding expected limits for the period 2017 to 2021. The principal component analysis further showed that both surface water and groundwater sites had high levels of contamination with increased chemical parameters. The results were compared against the different water quality guidelines. In an extensive monitoring program, water management systems must be properly implemented to mitigate impacts on water resources. [ABSTRACT FROM AUTHOR]

The characteristics and hazards of acid coal mine drainage (ACMD) were introduced, and the treatment methods of ACMD were described. Techniques that could be used for source prevention and process containment were analyzed. The widely used terminal treatment technologies at present were summarized, such as the active treatment technology based on neutralization, sulfidation, adsorption and membrane technology, and the passive treatment technology based on chemical, biological and chemical-biological combined method. It was summarized and concluded that the multi-technology combination process was the main trend of engineering application and an effective way for large-scale collaborative treatment of ACMD. Finally, the development prospect of ACMD treatment method was prospected. [ABSTRACT FROM AUTHOR]

Polycyclic aromatic hydrocarbons (PAHs) are a group of organic pollutants known for their persistence and potential carcinogenicity. Effective removal techniques are required since their presence in wastewater poses serious threats to human health and the environment. In this review study, iron oxide nanomaterials (IONs), a by-product of mining operations, recovered from acid mine water are used to investigate the adsorption of PAHs from wastewater. The mechanisms of PAH adsorption onto IONs are investigated, with a focus on the effects of concentration, temperature, and pH on adsorption efficiency. The better performance, affordability, and reusable nature of IONs are demonstrated by comparative studies with alternative adsorbents such as activated carbon. Economic and environmental ramifications highlight the benefits of employing recovered materials, while case studies and real-world applications show how effective IONs are in removing PAHs in the real world. This review concludes by discussing potential future developments in synthesis processes, areas for more research, and emerging trends in nanomaterial-based adsorption. This research intends to contribute to the development of more effective and sustainable wastewater treatment technologies by offering a thorough assessment of the present and future potential of employing IONs for PAH removal from wastewater. [ABSTRACT FROM AUTHOR]

The application of low-pressure nanofiltration (NF) was investigated for three different applications: water reuse from acid mine drainage (AMD), surface water containing natural organic matter (NOM) and agricultural reuse of microfiltered biologically treated sewage effluent (MF-BTSE). AMD contains many valuable rare earth elements (REEs) and copper (Cu) that can be recovered with fresh water. The NF90 membrane was investigated for recovery of fresh water from synthetic AMD. A steady permeate flux of 15.5 ± 0.2 L/m2h was achieved for pretreated AMD with over 98% solute rejection. NF90 achieved a high dissolved organic carbon (DOC) rejection of 95% from surface water containing NOM where 80% of the organic fraction was hydrophilic, mainly humics. The NF process maintained a high permeate flux of 52 LMH at 4 bars. The MF-BTSE was treated by NTR-729HF for agricultural reuse. NTR-729HF membranes were capable of rejecting DOC and inorganics such as sulfates and divalent ions (SO42−, Ca2+ and Mg2+) from MF-BTSE, with less than 20% rejection of monovalent (Na+ and Cl−) ions. The sodium adsorption ratio (SAR) was significantly reduced from 39 to 14 after treatment through NTR-729HF at 4 bar. The resulting water was found to be suitable to irrigate salt-sensitive crops. [ABSTRACT FROM AUTHOR]

The generation of acid mine drainage (AMD) characterized by high acidity and elevated levels of toxic metals primarily results from the oxidation and dissolution of sulfide minerals facilitated by microbial catalysis. Although there has been significant research on microbial diversity and community composition in AMD, as well as the relationship between microbes and heavy metals, there remains a gap in understanding the microbial community structure in uranium-enriched AMD sites. In this paper, water samples with varying levels of uranium pollution were collected from an abandoned stone coal mine in Jiangxi Province, China during summer and winter, respectively. Geochemical and high-throughput sequencing analyses were conducted to characterize spatiotemporal variations in bacterial diversity and community composition along pollution groups. The results indicated that uranium was predominantly concentrated in the AMD of new pits with strong acid production capacity, reaching a peak concentration of 9,370 µg/L. This was accompanied by elevated acidity and concentrations of iron and total phosphorus, which were identified as significant drivers shaping the composition of bacterial communities, rather than fluctuations in seasonal conditions. In an extremely polluted environment (pH < 3), bacterial diversity was lowest, with a predominant presence of acidophilic iron-oxidizing bacteria (such as Ferrovum), and a portion of acidophilic heterotrophic bacteria synergistically coexisting. As pollution levels decreased, the microbial community gradually evolved to cohabitation of various pH-neutral heterotrophic species, ultimately reverting back to background level. The pH was the dominant factor determining biogeochemical release of uranium in AMD. Acidophilic and uranium-tolerant bacteria, including Ferrovum, Leptospirillum, Acidiphilium, and Metallibacterium, were identified as playing key roles in this process through mechanisms such as enhancing acid production rate and facilitating organic matter biodegradation. [ABSTRACT FROM AUTHOR]

How to efficiently deal with waste acids and bases produced by industry has constantly been a tough question for scientists and engineers. Such acid–base wastewaters are normally treated by mixing to give neutral products (i.e., water and salts) and heat which is hard to collect and reuse. Therefore, there is a need for innovative approaches with high efficiencies and high-value added products. Here, we report an air/metal hydride battery with the function of both treating acid–base wastewaters and gathering the waste heat energy in the form of electricity. Remarkably, the proposed battery could exhibit a high coulombic efficiency of up to ca. 94%, along with an effective reduction in the acidity/alkalinity of waste acids/bases and a decent amount of electricity. The proposed battery device also demonstrates a stable operation in semi-flow mode over a two-day timescale, showcasing its potential scalability and long-term stability. Moreover, life cycle assessment results indicate that electricity retrieved from the treatment process is a key contributor to reducing environmental impacts. This work offers alternative opportunities for accelerating the transition to a waste acid–base circular economy. [ABSTRACT FROM AUTHOR]

Controlling and remediating water and soil pollution while efficiently utilizing solid waste is essential for comprehensive environmental protection and sustainable development, particularly in establishing green, low‐carbon economic systems in China. We evaluate the impact of initial concentration, flow rate, and bed height on breakthrough performance and adsorption capacity using the Tessier method under dynamic water flow conditions. Additionally, we analyze micromorphological changes in the red mud–loess mixture before and after breakthrough by acid mine drainage containing Pb and Cd in mining areas, employing soil column experiments and numerical simulations with COMSOL Multiphysics. Our findings suggest that reducing initial concentration and flow rate while increasing bed height leads to higher breakthrough time, saturation time, and adsorption capacity for Pb and Cd in the red mud–loess mixture (7 : 3). Furthermore, the red mud–loess blend (7 : 3) demonstrates sustained and efficient acid‐buffering capability in the presence of acid mine drainage containing Pb and Cd. Notably, under specific conditions (initial Pb content at 100 mg/L, a height of 7 cm, and flow rate set at 1 mL/min), the adsorption capacity of red mud–loess (7 : 3) reaches 17.30 mg/g. The prescribed minimum length for PRBs is 11.40 cm. Under specified conditions (Cd concentrations at 100 mg/L, a height of 5 cm, and a flow rate of 1 mL/min), the material exhibits a notable adsorption capacity of 29.91 mg/g, with a theoretical minimum length for PRBs at 8.95 cm. Increasing bed heights successfully remove Pb and Cd ions through chemical precipitation. The BDST model accurately describes the breakthrough curves of Pb and Cd and develops a correlation formula for the breakthrough time of red mud–loess PRB medium. As the saturation of Pb increases from 0.05 to 0.85, the maximum volume adsorption capacity of Pb increases from 1.78 to 2.98 mg/L, while for Cd, it increases from 4.15 to 7.87 mg/L. Elevating the bed height first triggers chemical precipitation, hence improving Pb and Cd removal. Consequently, the longevity of red mud–loess PRB in acidic mine effluent containing Pb and Cd surpasses predicted theoretical outcomes. These observations reveal correlations between the breakthrough length for red mud–loess permeable reactive barriers and the bed height. Furthermore, the distribution of Pb speciation within the red mud–loess mixture (7 : 3) is primarily governed by the presence of iron–manganese oxide, while the composition of Cd speciation is chiefly influenced by the carbonate form and iron–manganese oxide. After treating acidic mine wastewater with Pb and Cd, the red mud–loess mixed material (7 : 3) undergoes surface changes, shifting from smooth to rough due to H+ corrosion. Pores between particles enlarge, yet heavy metal ions, adsorbates, and precipitates reoccupy and cover the surface, transforming the particle morphology from dense lamellar to clustered spherical. Our innovative approach to combining waste materials for environmental remediation presents a cost‐effective and impactful solution for heavy metal pollution. [ABSTRACT FROM AUTHOR]

Green liquor dregs (GLD) is an alkaline by-product from the pulp and paper industry with a pH between 10 and 14. Today most of the produced GLD in Sweden is landfilled. As a fine-grained alkaline material, it might be possible to use it for acid-generating mining waste remediation. To increase the utilization, quality characteristics and environmental performance need to be determined. In this study samples were collected 5 times from 16 mills during a period of 2.5 years, and were characterized by analyzing dry matter content, loss on ignition (LOI) 550 °C and LOI 950 °C, elemental analysis, pH, electrical conductivity, and calorific value. The results were then evaluated using multivariate statistics (PCA) as well as being compared to other studies and Swedish till. The results show that even if GLD is heterogenous (both within a mill and between different mills) trends can be seen for samples from most mills. When samples do stand out, it is predominately related to the same four mills. Most of the studied parameters showed characteristics favorable for use as a remediant; however, TOC, sulfur, and some of the elements require further study. In general, this study concludes that GLD can be a viable option for the remediation of small orphaned sulfidic mining sites and thus worthy of further studies on the interaction between GLD and acidic mining waste. Overall, GLD can be a good alternative for cost-effective remediation of smaller orphaned mining sites. It is readily available in large quantities, has the qualities needed for remediation of many orphaned acidic mining sites, and can often be locally sourced near the mining site. The use of GLD for mining site remediation is likely also a more sustainable method compared to traditional remediation methods. [ABSTRACT FROM AUTHOR]

Climate influences near-surface biogeochemical processes and thereby determines the partitioning of carbon dioxide (CO2) in shale, and yet the controls on carbon (C) weathering fluxes remain poorly constrained. Using a dataset that characterizes biogeochemical responses to climate forcing in shale regolith, we implement a numerical model that describes the effects of water infiltration events, gas exchange, and temperature fluctuations on soil respiration and mineral weathering at a seasonal timescale. Our modeling approach allows us to quantitatively disentangle the controls of transient climate forcing and biogeochemical mechanisms on C partitioning. We find that ~3% of soil CO2 (1.02 mol C/m²/y) is exported to the subsurface during large infiltration events. Here, net atmospheric CO2 drawdown primarily occurs during spring snowmelt, governs the aqueous C exports (61%), and exceeds the CO2 flux generated by pyrite and petrogenic organic matter oxidation (~0.2 mol C/m²/y). We show that shale CO2 consumption results from the temporal coupling between soil microbial respiration and carbonate weathering. This coupling is driven by the impacts of hydrologic fluctuations on fresh organic matter availability and CO2 transport to the weathering front. Diffusion-limited transport of gases under transient hydrological conditions exerts an important control on CO2(g) egress patterns and thus must be considered when inferring soil CO2 drawdown from the gas phase composition. Our findings emphasize the importance of seasonal climate forcing in shaping the net contribution of shale weathering to terrestrial C fluxes and suggest that warmer conditions could reduce the potential for shale weathering to act as a CO2 sink. [ABSTRACT FROM AUTHOR]

Acid mine drainage (AMD), arising from mineral resource exploitation, has transformed into a significant global environmental issue for the mining sector, posing considerable risks to water, soil, ecosystems, and human health. In this study, the current status and cutting-edge dynamics of AMD remediation research were evaluated using a bibliometrics approach. Publications on AMD remediation were collected from the Web of Science Core Collection (WOSCC) database, and the relevant literature was analyzed quantitatively using various statistical methods, including keyword co-occurrence and burst analysis. In total, 2743 articles related to AMD remediation published from 1990 to 2023 were obtained. The number of publications tended to increase annually, with a relatively fast rate of increase in recent years. Recent research related to AMD remediation has mainly focused on the ecological risks, the environmental geochemical cycling, the application of sulfate-reducing bacteria and adsorption, and the recovery of heavy metals (HMs) and rare earth elements (REEs). It is anticipated that these topics of AMD remediation research are expected to be at the forefront of future research endeavors. In addition, the current status, advantages, and challenges of AMD remediation technologies are discussed from both active and passive management perspectives, providing a theoretical basis and reference for AMD remediation. [ABSTRACT FROM AUTHOR]

The progressive decline of the coal industry necessitates the development of effective treatment solutions for acid mine drainage (AMD), which is characterized by high acidity and elevated concentrations of heavy metals. This study proposes an innovative approach leveraging sulfate-reducing bacteria (SRB) acclimated to contaminated anaerobic environments. The research focused on elucidating the physiological characteristics and optimal growth conditions of SRB, particularly in relation to the pH level and temperature. The experimental findings reveal that the SRB exhibited a sulfate removal rate of 88.86% at an optimal temperature of 30 ◦C. Additionally, SRB gel particles were formulated using sodium alginate (SA) and carboxymethyl cellulose (CMC), and their performance was assessed under specific conditions (pH = 6, C/S = 1.5, T = 30 ◦C, CMC = 4.5%, BSNa = 0.4 mol/L, and cross-linking time = 9 h). Under these conditions, the SRB gel particles demonstrated an enhanced sulfate removal efficiency of 91.6%. Thermal analysis via differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) provided further insights into the stability and properties of the SRB gel spheres. The findings underscore the potential of SRBbased bioremediation as a sustainable and efficient method for AMD treatment, offering a novel and environmentally friendly solution to mitigating the adverse effects of environmental contamination. [ABSTRACT FROM AUTHOR]

The present study aims to develop a low-cost and sustainable composite material from solid waste to efficiently treat acid mine drainage (AMD). A modified reactor was used to produce the biochar-CaO composite from solid waste, which was characterized using XRD and SEM to determine the crystal structure, size, and surface morphology. The composite exhibited high adsorption capacity for AMD species, including Fe, Mn, and Mg metals, with an equilibrium point achieved at 300 min of contact time. The percent removal of AMD species varied with pH conditions, and the Langmuir isotherm model was found to describe the adsorption behavior of the composite adequately. The biochar-CaO composite showed a maximum adsorption capacity of 440 mg/g and held significant potential as an economical and efficient solution for AMD remediation. [ABSTRACT FROM AUTHOR]

The increasing mining activities have led to the problem of acid mine drainage (AMD) pollution. A method that combines biochar treatment as an adsorbent with wetland sediment treatment as a source of sulfate-reducing bacteria is used to address AMD effectively. This research aimed to determine the ability of biochar in combination with wetland sediment treatment to reduce sulfate and heavy metal content in acid mine drainage wastewater. This research was conducted on a laboratory scale in an AMD wastewater treatment reactor with the following treatments of biochar mixed with wetland sediment. Observations included sulfate content, pH, and heavy metal content. Scanning electron microscope (SEM) analysis was also performed on the biochar. SEM observations revealed the presence of small, dense, and irregularly shaped pores on the surface of the biochar. The results on day 30 showed that biochar mixed with wetland sediment was able to reduce sulfate concentration by 74.19% and reduced Pb by 73.79%, compared with treatment sediment only to 64.81% sulfate concentration and reduced Pb by 53.85%, treatment biochar only had reduced sulfate of 46.90% and reduced Pb by 58.67% and control 1.79% sulfate concentration and reduced Pb by 1.87%. [ABSTRACT FROM AUTHOR]