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Mining wastewater (MWw) in tailing ponds is one of the major obstacles in reusing tailings in practice and should be disposed preferentially. This paper investigated the feasibility of exploring MWw from copper mining as a source of mixing water to prepare activators for alkali-activated slag materials (AASM). Four MWws with different concentrations were prepared by using MWw to replace all, 1/2, 1/3, and 1/4 of tap water. The influences of different MWws on the setting time, hydration kinetics, hydration products, compressive strength, nano-mechanical properties, pore structure of AASM were investigated. Experimental results confirmed that MWw can be upcycled as the partial or total mixing water for alkali-activated slag materials. The influence of MWw on the properties of AASM was related to its concentration. MWw with low concentrations accelerated the hydration of slag at early ages, nevertheless raw MWw without dilution slightly impeded the hydration process. Although no new hydration product is induced by adding MWw, both NMR pore analysis and nanoindentation testing suggested that the addition of MWw densified the hydration products, which is beneficial for mechanical properties of AASM. As a result, the 28d compressive strengths of AASM increased with increased concentrations of MWw by − 0.8 to 19.9%. Through this paper, a low-cost, green and practical method was developed as an option for the disposal and recycle of MWw. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • E. coli for REEs enrichment excelled Non-REEs, causing HREEs/LREEs fractionation. • 4 cycles in E. coli prove the stability of REEs recovery from mining wastewater. • REEs recovery mechanisms involves electrostatic attraction, ion exchange. • The economic viability of Ecoli 's recovery is shown by the cost assessment. Microbes used for the recovery of rare earth elements (REEs) from mining wastewater indicated traces of Escherichia coli (E. coli , 2149.6 μg/g), Bacillus sphaericus (1636.6 μg/g), Bacillus mycoides (1469.3 μg/g), and Bacillus cereus (1083.9 μg/g). Of these, E. coli showed an affinity for REEs than non-REEs (Mn and Zn). The amount of heavy REEs adsorbed (1511.1 μg/g) on E. coli was higher than light REEs (638.0 μg/g) due to the process of increasing adsorption with decreasing ionic radius. Additionally, E. coli demonstrated stability in the recovery of REEs from mining wastewater, as evidenced by 4 cycles. SEM-EDS, XPS and FTIR showed that REEs had a disruptive effect on cells, REEs absorbed and desorbed on the cell surface including ion exchange with ions such as Na+, ligand binding with functional groups like –NH 2. Finally, the cost assessment confirmed the economically feasible of E. coli in recovery of REEs from mining wastewater. [ABSTRACT FROM AUTHOR]

While microbial technologies, which are considered to be environmentally friendly, have great potential for the recovery of rare earth elements (REEs) from mining wastewater, their applications have been restricted due to a lack of efficient biosorbents. In this study, a strain of Pseudomonas psychrotolerans isolated from yttrium-enriched mine soil was used to recover yttrium (Y(III)) from rare-earth mining wastewater. At an initial Y(III) dose of 50 mg L−1, the amount of Y(III) adsorbed by P. psychrotolerans reached 99.9 % after 24 h. Various characterization techniques revealed that P. psychrotolerans adsorbed Y(III) mainly through complexation of oxygen-containing functional groups and electrostatic interactions. A high level of adsorption efficiency (>99.9 %) was maintained after five consecutive adsorption/desorption cycles, indicating that P. psychrotolerans was highly reusable. While the efficiency of adsorbing Y(III) by P. psychrotolerans decreased (34.4 %) in actual rare earth mining wastewater, selectivity toward other REEs (≤ 18.4 %) was still observed. Consequently, this study provides a promising green, environmentally friendly and sustainable microbial approach for the selective recovery of REEs from rare earth wastewater. [Display omitted] • P. psychrotolerans isolated from mining soil selectively recovered yttrium from wastewater. • P. psychrotolerans removed 99.9 % of 50 mg L−1 yttrium. • Recovery of yttrium involved electrostatic adsorption, surface complexation and EPS. • P. psychrotolerans was a potential practical biosorbent for rare earth element recovery. [ABSTRACT FROM AUTHOR]

This study presents the inaugural demonstration of a microbial electrochemical cell (MXC)-based biosensor for naphthenic acids (NAs) detection in oil sands process water (OSPW) from a mining site. During the calibration process, different operating parameters were evaluated, including standing times (3 – 12 hours) and charging durations (5 – 20 minutes) within the charging-discharging cycles. The observations ascertained that a combination of a 12-hour standing period followed by a 15-minute charging period yielded the optimal current output when measuring NA concentrations ranging from 4.98 to 24.9 mg/L in real OSPW samples (diluted to concentrations of 20–100 %). Subsequently, incorporating diverse inoculum sources from MXCs led to significant signal output improvements, with one sustained on a mixture of cyclohexane carboxylic acids, commercial naphthenic acids, and real OSPW, and another exposed to acetate medium for over four years. Moreover, integrating quorum sensing (QS) autoinducers (10 μM) increased the current generation, highlighting the potential for more sensitive detection capabilities. Ultimately, our MXC biosensor could enable a cost-effective and rapid detection of OSPW NAs, offering a potential alternative for environmental surveillance. [Display omitted] • Microbial electrochemical biosensor demonstrated for detecting NAs in real OSPW. • 12-h standing/15-min charging times were the best calibration method for biosensor. • Acetate-fed reactor effluent as an inoculum greatly boosted the current output. • Exogenous QS autoinducer (C6-HSL) further increased the biosensor's sensitivity. [ABSTRACT FROM AUTHOR]

Climate change and related issues such as water scarcity and the urgent need for a transition to sustainable energy sources have motivated the development of novel processes and techniques that can be applied for water treatment, recovery and reuse. Among these emerging processes, membrane distillation in its different configurations has been extensively studied and reported in the literature. A bibliometric analysis was performed to investigate the research documents published in the scientific database Scopus until 2024, related to use of membrane distillation for water recovery and reuse. The main quantitative attributes of the research during this period were identified. The results of this analysis showed a very low scientific production until 2005, followed by a rapid exponential increase since then. The combined contribution of the two most productive countries (China and USA respectively) accounted for more than 41 % of the total number of publications, followed by Australia and Saudi Arabia, which occupied the third and fourth positions in the ranking. Chemical engineering was the most important subject category (57.4 % contribution), closely followed by environmental sciences. The review of the most cited documents and keywords showed that membrane wetting is one of the main drawbacks that can reduce the performance of membrane distillation and the use of innovative superhydrophobic, omniphobic or Janus membranes resulted an adequate solution to avoid this problem. Moreover, the desalination of seawater, brines and other highly saline solutions can be considered as the most studied application of membrane distillation. The consideration of the energetic aspects of membrane distillation and its coupling with other technologies were identified as relevant topics during the bibliometric network analysis. Special attention was given to the potential of membrane distillation for water recovery and reuse in the Chilean context of water stress for the production of drinking water and the treatment of domestic greywater and wastewater from mining and other industrial activities. • A bibliometric analysis of membrane distillation potential to recover water to be reused • Exponential growth of the research in this topic (led by China, USA and Australia) • Membrane wetting as the main drawback, which can be minimized using innovative membranes • Energy aspects are critical, promoting the use of waste heat and renewable energy sources • Potential to treat greywater and wastewater from mining activities and other industrial sectors [ABSTRACT FROM AUTHOR]

• Iron sulfide nanoparticles was biosynthesized by Pinus massoniana Lamb. • nFeS showed a highly selectively recover Y(Ⅲ) from mining wastewater. • The adsorption of Y(Ⅲ) was predominant by the capping layer. • The result showed that effective desorption of Y(Ⅲ) from mining wastewater. The selective recovery of rare earth elements (REEs) from mining wastewater has become a hot research topic due to the increasing industrial value of REEs. Herein, biosynthetic iron sulfide nanoparticles (nFeS) were deployed as a superior adsorbent to selectively recover Y(Ⅲ) from mining wastewater. The maximum adsorption efficiency achieved for of Y(Ⅲ) by nFeS was 81.2 % compared to only 38.7 % for Eu(Ⅲ) and 20.8 % for Mn(Ⅱ), demonstrating that nFeS had a high selective adsorption for Y(Ⅲ). To understand the origins of the high selectivity of nFeS, the removal of REEs by the capping layer and the FeS-core were separately investigated. Specifically, given the hard and soft acid base principle (HASB) and the square antiprism coordination geometry of Y(Ⅲ), the adsorption of Y(Ⅲ) by the capping layer was predominantly attributed to C O and –NH 2 serving as a monodentate ligand to strongly chelate with Y(Ⅲ), while Y(Ⅲ) interacted with Fe–O on the FeS-core and –COOH more via ion-exchange with Y(Ⅲ). Collectively, cooperative interactions between the capping layer and FeS-core resulted in the overall highly selective adsorption of Y(Ⅲ) by nFeS, suggest this approach has significant potential for future practical remediation and recovery applications to Y(Ⅲ) rich mining wastewaters. [ABSTRACT FROM AUTHOR]

• A Fe-Chitosan-coated sensor was developed for in situ As(III) detection. • The sensor was successfully applied for mining wastewater and soil leachate. • The sensor displayed good selectivity and reproducibility in real wastewater. • The interference from metal ions was found negligible for As(III) detection. A novel As(III) sensor was developed by co-electrodepositing a Fe-Chitosan composite to a screen-printed carbon electrode sensor. The newly developed Fe-Chitosan-coated carbon electrode sensor exhibited successful As(III) detection in mining wastewater and soil leachate using square wave anodic stripping voltammetry (SWASV). A noticeable peak was observed at +0.15 V associated with stripping current of As(III) for both real wastewater samples. The calibration curves showed strong correlations with respect to As(III) with the limit of detection (LOD) of 1.12 ppb for mining wastewater and 1.01 ppb for soil leachate, respectively. Lower relative standard deviations (RSD) were obtained with 2.91% for mining wastewater and 4.54% for soil leachate during repeated measurements (n = 8), respectively, indicating enhanced stability for As(III) detection in the real wastewater application. The interference from copper and other metal ions (e.g., Zn(II), Pb(II) and Cd(II)) was found negligible for As(III) detection using the polymer modified Fe-coated electrode sensor, which suggests that the Fe-chitosan composite imparted the selectivity in the presence of other metal ions to As(III) detection in complex water matrix. These results demonstrate the applicability of a novel Fe-Chitosan-coated carbon electrode sensor to real wastewater As(III) pollution monitoring with the acceptable range of characteristics. [ABSTRACT FROM AUTHOR]

[Display omitted] • Unique challenges of mining wastewater, antisclants (AS) for MLD/ZLD. • Coupling of AS and antiscalant deactivation technology (ASDT) for higher recovery. • Advantages and disadvantage of ASDT for the mining wastewater application. Mining wastewater is inherently challenging to achieve zero or minimal liquid discharge (ZLD/ MLD) due to the high scale of the wastewater and the physical site constraints. This article highlights contextualized challenges for mining applications and also proposes a novel perspective on coupling antiscalants (AS) and downstream antiscalant deactivation technology (ASDT). ASDT is a relatively new concept that overcomes the limitation of water recoveries at the maximal TDS of 70 g/L by treating and desalting brines. The coupling of AS and ASDT can hence result in lower treatment costs by enhancing crystallization performance and enhancing water recovery with higher RO recoveries. Mining-specific scales, unique wastewater combinations, and physical constraints of mining sites are bottlenecks, and their potential mitigation methods are further explored in this article. Overall, this article provides an overview of the AS and ASDT applications and provides insightful future perspectives to address current challenges in mining wastewater applications. [ABSTRACT FROM AUTHOR]

Wastewater from the mining industry is a concern because most of the time it contains heavy metals with concentrations above permissible levels, posing a threat to terrestrial and aquatic life. The study was conducted to evaluate the effectiveness of locally available waste materials (waste rock, tailings, coal ash clinker, and slag) generated by BCL (Ltd) mine, a copper and nickel mining and smelting company in Botswana, for removal of nickel and copper from the real mining wastewater. Batch adsorption studies were conducted to establish the adsorptive efficiency and kinetics of each media with respect to nickel and copper ions. The best media was further evaluated through fixed bed column studies at 24 and 48 h empty bed contact time. The results indicate that the percentage removal for coal ash clinker, waste rock, smelter slag and tailings was 98%, 15%, 3% and −3% with respect to copper ions, and 46%, 9%, 7% and 2% with respect to nickel ions for each media respectively. Coal ash clinker followed pseudo first order kinetic model and Langmuir isotherm model with respect to nickel ions indicating the dominance of physisorption and mono layer coverage respectively. The Langmuir separation factor (R L ) was 0.37 suggesting favourable adsorption onto the media. Fixed bed column studies revealed that copper was completely retained in the bed at both 24 and 48 h contact times. In the case of nickel, removal efficiency ranged between 83% and 99% when contact time was 48 h and between 68% and 99% when the contact time was reduced to 24 h. Breakthrough was not reached after 19 bed volumes. It can be concluded that coal ash clinker is a better candidate for the removal of copper and nickel ions from mining wastewater. [ABSTRACT FROM AUTHOR]

Naturally occurring manganese (Mn) oxide minerals often form by microbial Mn(II) oxidation, resulting in nanocrystalline Mn(III/IV) oxide phases with high reactivity that can influence the uptake and release of many metals (e.g., Ni, Cu, Co, and Zn). During formation, the structure and composition of biogenic Mn oxides can be altered in the presence of other metals, which in turn affects the minerals' ability to bind these metals. These processes are further influenced by the chemistry of the aqueous environment and the type and physiology of microorganisms involved. Conditions extending to environments that typify mining and industrial wastewaters (e.g., increased salt content, low nutrient, and high metal concentrations) have not been well investigated thus limiting the understanding of metal interactions with biogenic Mn oxides. By integrating geochemistry, microscopic, and spectroscopic techniques, we examined the capacity of Mn oxides produced by the Mn(II)-oxidizing Ascomycete fungus Periconia sp. SMF1 isolated from the Minnesota Soudan Mine to remove the metal co-contaminant Co(II) from synthetic waters that are representative of mining wastewaters currently undergoing remediation efforts. We compared two different applied remediation strategies under the same conditions: coprecipitation of Co with mycogenic Mn oxides versus adsorption of Co with pre-formed fungal Mn oxides. Co(II) was effectively removed from solution by fungal Mn oxides through two different mechanisms: incorporation into, and adsorption onto, Mn oxides. These mechanisms were similar for both remediation strategies, indicating the general effectiveness of Co(II) removal by these oxides. The mycogenic Mn oxides were primarily a nanoparticulate, poorly-crystalline birnessite-like phases with slight differences depending on the chemical conditions during formation. The relatively fast and complete removal of aqueous Co(II) during biomineralization as well as the subsequent structural incorporation of Co into the Mn oxide structure illustrated a sustainable cycle capable of continuously remediating Co(II) from metal-polluted environments. [Display omitted] • Co(II) is quickly removed from simulated mining wastewater by mycogenic Mn oxides. • Co(II) is adsorbed onto and incorporated into fungal Mn oxides. • Fungal Mn oxides co-precipitated with Co(II) or pre-formed showed no difference in Co(II) removal ability. • Mycogenic Mn oxides may provide an effective Co bioremediation strategy. [ABSTRACT FROM AUTHOR]

Electrode material is the key factor for improving the electrochemical performance of capacitive deionization. In this study, a multichannel electrode material derived from soybean straw was prepared by pyrolytic carbonization and dual-activation, characterized, and used as an electrode material in capacitive deionization (CDI) cells to remove sulfate. The results showed that the sulfate adsorption capacity of dual-activated CA-NPSSC-1 of 17.16 mg/g was higher than that of pristine SSC (3.28 mg/g) due to its larger specific surface area, suitable pore structure, superior conductivity, and larger specific capacitance. The electrosorption mechanism of CA-NPSSC-1 electrode included EDL ion storage and pseudocapacitance storage. The EDL contribution and pseudocapacitance contribution were 72.06 % and 27.94 %, respectively, at a scan rate of 5 mV/s. Actual wastewater experiments have shown that the sulfate concentration in mining wastewater was reduced to 158.85 mg/L after recycling treatment, which meets the relevant standards. This work provides new ideas and methods for the treatment of high-salinity mining wastewater. [Display omitted] • The CA-NPSSC-1 electrode was demonstrated to have high capacitive deionization performance and regeneration performance. • Electrostatic adsorption and non-electrostatic adsorption (physical adsorption and chemical adsorption) were involved. • The contributions of EDL storage and pseudocapacitive storage to electroabsorption were 72.06% and 27.94%, respectively. • The prepared CA-NPSSC-1 electrode could effectively treat actual mining wastewater. [ABSTRACT FROM AUTHOR]

[Display omitted] • A hybrid ZIF-8@FeNPs was successfully prepared. • The removal mechanism of Sb (V) was proposed. • Sb(V) in mining wastewater (1.121 mg·L−1) was removed 89.7 %. • ZIF-8@FeNPs was separated and recycled. The removal of antimonate (Sb(V)) species from wastewaters has become a growing concern due to their known genotoxicity and carcinogenicity. In this paper, a hybrid ZIF-8@FeNPs material was synthesized from Zeolite Imidazole Framework-8 (ZIF-8) and zero-valent iron nanoparticles (n ZVI) and subsequently used to remove Sb(V) from aqueous solution. Characterization indicated that ZIF-8@FeNPs were successfully synthesized and that the valence state of Sb(V) did not change during the removal process, where adsorption of Sb(V) was facilitated by the high specific surface area and porosity of the hybrid. Advanced characterization also showed that Zn-OH and iron oxides were adsorbed on the material after complexation with Sb(V). Kinetic, isothermal, and thermodynamic modeling indicated that the adsorption process followed pseudo-second-order kinetics, via multilayer adsorption which was spontaneous and endothermic. A Sb(V) removal mechanism based on adsorption was proposed. In mining wastewater containing 1.121 mg·L−1 Sb(V), 89.7 % could be removed by the material. During repeated reuse of ZIF-8@FeNPs for the removal of 1 mg·L−1 Sb(V) through four successive cycles, the removal efficiency was still relatively high (39.1 %) after the fourth cycle indicating good potential for practical applications. In addition, ZIF-8@FeNPs also exhibited magnetic properties, which demonstrated that Sb(V) could be easily recovered from wastewater post removal by ZIF-8@FeNPs. [ABSTRACT FROM AUTHOR]

[Display omitted] • COFs and CNTs composites were synthesized by in-situ synthesis. • The synergistic effect improved the adsorption capacity and selectivity. • The removal mechanism of samples was clarified through various characteristic modes. • The problem of U (VI) removal from the rare earth tailings wastewater had been solved. The wastewater containing uranium produced in the mining process is harmful to the environment and life safety due to the inherent biotoxicity and radioactivity of uranium. In this paper, 4,4′-diamino-[1,1′-biphenyl]-3,3′-diol and 2,4,6-triformylphloroglucinol were in situ synthesized β -ketoenamine covalent organic frameworks (COFs) on the surface of carbon nanotubes (CNTs) to obtain a composite of CNT/COF-OH for removal uranium in the rare earth tailings wastewater. Grafting COFs with a large number of specific uranium-binding groups and redox-active sites on the surface of CNTs, CNT/COF-OH can effectively enhance the uranium ion selectivity and adsorption capacity. Furthermore, CNTs have good electron transport capacity and π-conjugation properties, electrons can be effectively transferred from CNTs to COFs, which increases the electron density of the adsorption functional groups, resulting in an increase of the adsorption energy and reductive activity for U (VI), thus improving the removal efficiency. In addition, the skeleton of COFs can be supported by CNTs, thus reducing collapse. Through the synergistic effect of composite, CNT/COF-OH had a good uranium adsorption capacity of 518.2 mg g−1. The adsorption capacity of CNT/COF-OH was increased by 390.7 %, 54.6 %, and 84.5 % compared with those of single CNTs, COF-OH, and mixed CNT + COF-OH, respectively. The selective separation coefficient of CNT/COF-OH was 1.6 times higher than that of COF-OH. The experiment of uranium removal was carried out in the rare earth tailings wastewater using CNT/COF-OH, the removal rate reached 96.7 %. The COFs modified CNTs with synergistic effect have important theoretical and practical significance for the safety problems caused by harmful ions in wastewater. [ABSTRACT FROM AUTHOR]

Heavy-metal-bearing wastewater is among the most formidable challenges the mining industry currently faces in maintaining its social license to operate. Amongst the technologies available for metal ion adsorption, bioinspired engineering nanomaterials have emerged as one which exhibits great promise. However, current processes used for the preparation of adsorbents (including nanoscale activated carbon and biochar) represent a source of adverse impacts on the environment. In contrast, the application of biogenic-nanoparticles, i.e., those derived from processes catalysed by microbiota, has received significant attention in the last few years. Coupled with this, the use of naturally occurring reagents is of major importance for the sustainability of this emerging industry. This paper analyses the life cycle assessment (LCA) of the synthesis of adsorbents derived from agricultural wastes. Moreover, rather than simply recovering the ecotoxic metals from wastewater, the potential to valorise dissolved metals into high-value metallic nanoparticle products is discussed. LCA analysis revealed that the adsorbent had some adverse impact on the environment. The agricultural wastes contributed 27.86% to global warming, 54.64% to ozone formation, 33.06% to fine particles, and 98.24% to marine eutrophication. Mining wastewater is an important, and largely currently unexploited, source of metal value. However, the often-low concentration of such metals dictates that their conversion into high-value products (such as engineered nanoparticles) is an important new research frontier. Within this the use of biosynthesis methods has emerged as having great potential due to a range of beneficial attributes, including low cost, high efficacy and/or environmental compatibility. [Display omitted] • LCA of adsorbents from agricultural wastes revealed an impact on the environment. • Mining wastewater has high potential as a source of multi-metal nanoparticles. • The challenges of nano-synesis in mining wastewater lie in the presence of cations. [ABSTRACT FROM AUTHOR]

Low nitrogen (N) removal efficiency limits the potential of microalgae technology for the treatment of high nitrogen and low carbon rare earth tailings (REEs) wastewater. In this study, waste corncob was utilized as a biocarrier immobilizing Chlamydopodium sp. microalgae to realize high-efficient treatment of the REEs wastewater. In only 2.5 d, corncob-immobilized microalgae allowed the residual concentrations of N lower than the emission standards, and ammonia nitrogen (NH 4 +-N) removal rate is 83.3 mg L−1·d−1, total inorganic nitrogen (TIN) removal rate is 86.7 mg L−1·d−1, which was 18.5 times that of the previously-reported microalgae (4.68 mg L−1·d−1). Compared with other microalgae immobilization carriers, corncob possesses the ability to release available carbon sources for microalgae. Composition analysis and sugar verification experiments showed that the main content of TOC released by corncob was monosaccharide, and in a certain range, the removal rate of N was positively correlated with the TOC concentration. The utilization of biomass wastes with dual functions as biological carriers has great potential to improve the performance of microalgae, and is conducive to the development of engineering applications. [Display omitted] • Rapid removal of NH 4 +-N and TIN by microalgae was achieved in REEs wastewater. • The removal efficiency of TIN can reach 100%, and rate can reach 86.7 mg L−1·d−1. • The removal rate of N by corncob-immobilized microalgae reached the highest. • Corncob possess dual functions of biocarrier and available carbon source. [ABSTRACT FROM AUTHOR]

Arsenic contamination is an increasing global environmental problem, especially in mining industry wastewater where both arsenite (As(III)) and arsenate (As(V)) have been routinely detected. In this paper, a novel porous metal-organic framework material (ZIF-8) was composited with iron nanoparticles (FeNPs) to form a functional material (ZIF-8@FeNPs) for the simultaneous removal of As(III)/(V) from wastewater. The material effectively removed both As(III) and As(V) with removal efficiencies of 99.9 and 71.2%, respectively. Advanced characterization techniques including X-ray photoelectron spectroscopy (XPS) and Fourier infrared (FTIR) indicated that removal of As(III) and As(V) involved complex formation. Adsorption kinetics followed a pseudo-second order kinetics indicating adsorption involved chemisorption. After four cycles of reuse the he removal rate of As species was still relatively high at > 60% When ZIF-8@FeNPs were used to remove As from real wastewater from acid mines the removal efficiency was 94.27%. Finally, a As(III) and As(V) removal mechanism was proposed. [Display omitted] • ZIF-8@FeNPs can effectively remove As(III) and As(V). • Removal of As(III) and As(V) by forms complex. • The adsorption process is one of chemisorption. • A 94.27% of As (V) in mining wastewater was removed. [ABSTRACT FROM AUTHOR]

Limestones and their modifications from Nordkalk Corporation (Finland) flotation fines (FF) and filter sand (FS) as potential adsorbents for AMD treatment and wastewater purification from Cu, Fe, Zn and Ni ions were studied. Limestones were capable of binding significant amounts of Cu and Fe from synthetic AMD solutions and wastewater, while unmodified limestones were not good for Zn and Ni removal. Two methods of surface area modification were suggested. The first one with 2 M solution of NaCl and the second one with wastewater from Norilsk Nickel Harjavalta. The structure of materials and their surface area were characterized by SEM, EDX, MIR spectroscopy and nitrogen adsorption methods. Optimal amount of adsorbents for different model and real solutions was found. Adsorption kinetics showed that the adsorption equilibrium was reached within approximately 8 h. The kinetic data fits to a pseudo second order model with correlation coefficients greater than 0.999. The adsorption capacity was the highest at solution pH range of 6–7. Langmuir, Toth and Sips models were used to fit the adsorption isotherms. Based on the parameters calculated from models, the adsorption capacity decreased in the order of Cu > Fe > Zn > Ni for FF and Fe > Cu > Zn > Ni for FS. The research showed that the proposed modified limestones can be successfully used for AMD neutralization and removal of Cu(II), Fe(III), Zn(II) and Ni(II). [ABSTRACT FROM AUTHOR]

To study the effects of mining activities on the agricultural environmental quality, four representative paddy fields distributed at different towns (HSG, SNJ, NT and THJ) of Y County, northern Hunan Province, were investigated. It was found that the paddy fields at HSG, SNJ and NT were heavily polluted by heavy metals, especially Cu, Zn and Cd, due to long-term irrigation with the nearby stream water contaminated by mining wastewater. In contrast, the paddy field at THJ, far away from mining sites, was not polluted by heavy metals and regarded as a control. The rice grain produced at the fields of HSG, SNJ and NT had a high risk of Cd contamination. Soil enzyme activities and microbial biomass were significantly inhibited by the heavy metal pollution. Microbial biomass carbon and microbial biomass nitrogen at a severely polluted site of the field at HSG were only 31.6% and 64.4% of the controls, respectively. The activities of dehydrogenase, urease, catalase, acid and neutral phosphatase and sucrase were only 25.2%, 49.3%, 52.4%, 94.7%, 53.2% and 87.8% of the controls, respectively. The microbial parameters were mostly negatively significantly correlated with the contents of Cu, Zn, Cd and Ni in the paddy fields, fully suggesting that the heavy metals had toxic effects on microbial processes. Furthermore, the principal component analysis and cluster analysis indicated that the activities of dehydrogenase and microbial biomass carbon were the most sensitive to the toxicity of heavy metals and could be used as eco-indicators of soil pollution in the study areas. [ABSTRACT FROM AUTHOR]

[Display omitted] • Advantages and limitations of MSPs for wastewater treatment were discussed. • IX can be a resourceful tool to recover metal by products from wastewater. • Equilibrium and kinetic models for batch and continuous systems were summarized. • Integrated systems are pointed out as future perspectives for by-products recovery. A future scenario of water scarcity, combined with minerals resources exhaustion, led to the development of treatments capable to achieve water reuse and by-products recovery. Whereas most membrane separation processes (MSPs) guarantee a wastewater treatment at reuse level, their concentrate represents in most cases a liability due to its greater complexity and environmental impact. However, rather than its treatment, the concentrate from mining wastewater treatment is presented as an opportunity for by-products recovery by ion exchange (IX) resins. It was summarized the efficiency and limitations of MSPs (pressure-, thermal-, osmotic-, and electrical-driven processes) for reuse water reclamation from acid mining wastewater, followed by a critical discussion of IX process for metallic compounds recovery from their concentrate. The advantages of IX over conventional treatment and disposal practices were highlighted, with special attention given to factors that affect the IX equilibrium, kinetics, and thermodynamics, in batch and continuous operation, in addition to the models used to describe them. Models for error estimations were presented as well along a criticism for the use of linearized models for data interpretation. An overview of the lab-scale studies pointed out that IX would be an interesting alternative for concentrated solutions valorization. As an attempt to scale up IX for pilot- and full-scale applications, it was presented a step-by-step mass balance that allows for a batch system design and resins mass estimation for a given concentrate flow rate. Finally, future perspectives are presented pointing out to integrated IX system, impregnated resins, and columns systems, that represents knowledge gaps to be covered in the next few years. [ABSTRACT FROM AUTHOR]

The ultraviolet light activation of persulfate (PS) under alkaline conditions was evaluated for treating hexacyanoferrate (III) ion ([Fe(CN) 6 ]3-). The effect of the wavelength type (i.e., UVA and UVC), initial PS concentration (0.3, 0.6, and 0.9 g L−1), and pH value (11 and 13) on the degradation of 50 mg L−1 of [Fe(CN) 6 ]3- were studied. Finally, the role of the main degrading agents (SO 4 •-, O 2 •-, or HO•) involved in the degradation process was determined using scavengers and a degradation pathway for [Fe(CN) 6 ]3- was proposed. Results show that [Fe(CN) 6 ]3- can be decomposed by UVC light, while UVA is not effective neither in [Fe(CN) 6 ]3- photolysis nor in the activation of PS. Alkaline activation alone at pH 13 can also not degrade the cyanocomplex. However, the combination of UVC with PS (0.3 g L−1) at pH 13 showed high efficiency in the elimination of [Fe(CN) 6 ]3-, achieving 93.3% of removal after 125 min of treatment. The highest CN- release and Fe dissolved removal also occurs at pH 13 and 0.3 g L−1 PS. Further increases in initial PS concentrations may lead to an excess of radicals in solution, resulting in detrimental recombination reactions that affect the efficiency of the process. Quenching tests showed that the importance of radicals involved in the degradation of [Fe(CN) 6 ]3- follows the order: HO• > O 2 •- >>> 1O 2 or SO 4 •-, and allowed to demonstrate that singlet oxygen could participate in the UVC photolysis of [Fe(CN) 6 ]3-. All these results suggest the feasibility of this technology to treat this type of industrial wastewater efficiently. [Display omitted] • [Fe(CN) 6 ]3- needs the presence of light to be degraded. • Alkaline activation of S 2 O 8 2- alone is ineffective to eliminate [Fe(CN) 6 ]3-. • HO• plays the main role in the degradation of [Fe(CN) 6 ]3-. • A mechanistic proposal for the [Fe(CN) 6 ]3- transformation is shown. [ABSTRACT FROM AUTHOR]

[Display omitted] • CN− showed low degradation removals by photolysis or persulfate processes. • The presence of O 2 has a beneficial effect on CN− degradation. • Hydroxyl and sulfate radicals are responsible for CN− elimination. • Radicals generation favors CN− transformation to CNO− and NO 3 −. • UVC/PS showed high CN− degradation in the presence of additional ions. This work studied the influence of several parameters on free cyanide (CN−) degradation (50 mg L−1) by the UVC-activated persulfate (PS) at alkaline conditions (UVC/PS). Firstly, photolysis and alkaline activation of PS were evaluated. Then, the effect of initial PS concentration (0.2, 0.4, and 0.6 g L−1) and dissolved oxygen in solution (absence/presence) were studied. Lastly, the influence of phosphate, carbonate, and nitrate presence at different concentrations (50, 150, 350, and 500 mg L−1) on CN− elimination was tested. Additionally, the electric energy per order (E EO), a measure of the energy consumption in the process was determined, and a mechanistic view of CN− degradation was proposed. The results show that photolysis and alkaline activation of PS degraded 8 and 11% of CN−, respectively, whereas their combination presented a synergistic effect on CN− pollutant elimination. While oxygen had a vital role in photolysis due to the formation of 1O 2 to oxidize CN− to CNO−, HO• and SO 4 •− were primarily responsible for CN− degradation by UVC/PS. It was also found that cyanide removal followed a pseudo-first-order kinetics whose apparent reaction rate constant (k) increased from 0.0104 to 0.0297 min−1 as the initial concentration of PS increased from 0.2 to 0.6 g L−1, indicating a strong dependency of the removal efficiency on the PS amount. Remarkably, cyanide degradation by the combined UVC/PS showed a high CN− conversion and selectivity even in the presence of high concentrations of phosphate, carbonate, and nitrate ions (500 mg L−1), which resulted in CN− removals higher than 80% after 60 min of degradation treatment. Furthermore, the E EO values were similar in the presence and absence of phosphate or carbonate; however, they decreased slightly with nitrate presence. All these results suggest the feasibility of the combined UVC/PS process for the elimination of cyanide such as that found in mining wastewater. [ABSTRACT FROM AUTHOR]

This study evaluated the effect of dimethyl sulfoxide (DMSO) intercalation in natural kaolinite (KN) on etheramine adsorption. The effects of the parameters pH, initial etheramine concentration and adsorbent mass were investigated using central composite design. Optimal conditions were determined using response surface methodology. Theoretical calculations were performed to optimize the geometries of the kaolinite, DMSO, KDMSO, molecular and protonated etheramine structures, as well as the interaction between etheramine and kaolinite. XRD and FTIR results confirm the intercalation of DMSO into kaolinite, the intercalation process caused a significant increase in the isoelectric point. The results show that the adsorption was more efficient in pH 10 and etheramine concentration of 400 mg L-1 for both adsorbents, and 0.1 g of KN and 0.2 g of KDMSO. The kinetic data most accurately fit the pseudo-second-order model. The fitting of the experimental data to the isotherm models indicated that the Sips is the most appropriate model. The calculation of Eads revealed that mechanism of etheramine removal by KN and KDMSO involve chemisorption. The reusability tests determined that after four uses, the etheramine removal efficiency does not change significantly, enabling the use of kaolinite for wastewater treatment. Theoretical studies have enabled a better understanding of the intercalation process. In addition to increasing the interlayer spacing (2.50–8.01 Å), the introduction of the DMSO molecule modifies the charge distribution in the kaolinite structure, which contributes to the increase in the amount of etheramine adsorbed. The protonated etheramine molecule interacts more effectively with the KDMSO. [Display omitted] • The introduction of DMSO creates new adsorption sites in the kaolinite. • DMSO causes an increase in the kaolinite layer distance of approximately 8.01 Å. • Etheramine adsorption in kaolinite and intercalated kaolinite involve chemisorption. • The DMSO molecule causes a change in the kaolinite energy map. • The protonated etheramine interacts more strongly with the kaolinite-DMSO system. [ABSTRACT FROM AUTHOR]

This study focuses on developing an improved grey water footprint (GWF) to evaluate the pollution of noncarcinogenic heavy metals (NHMs) in mine wastewater. The conventional GWF only considers independent dilution, and the health hazards of NHMs are accumulative. The improved GWF is designed on the basis of health risk theory to solve this problem. The improved GWF involves three procedures: (i) deducing the virtual water volume to dilute the accumulative health risk within the allowable limit, (ii) calculating the water pollution level (WPL) to make comprehensive evaluation, and (iii) distinguishing the contribution rates of exposure pathways. The evaluation of NHM pollution in Dexing City shows the following conclusions. (i) The comprehensive GWF of NHMs in Dexing City is 2.31 billion m3, and the WPL is 0.979, which belongs to the "high" grade. Cu, Pb, and Zn account for 98.09%, 1.10%, and 0.89% of GWF, respectively. The contribution rates of drinking and contact are 99.02% and 0.98%, respectively. The risk is majorly introduced by the load of Cu in Dexing copper mine. (ii) Compared with the conventional GWF, the improved GWF has better capacities in representing the accumulative effect of NHMs and distinguishing the effects of different exposure routes on human health. [ABSTRACT FROM AUTHOR]

• Spacer and membrane material affected the maximum recovery rate. • Elevated values of metals (>95.7%) and acidy retention (>99.9 %) were achieved. • The membranes maintained its properties after 240 days of exposure to the effluent. • Spacer addition improved permeate recovery rate up to 11.2% • The low fouling propensity corroborate for long-term operation. Direct contact membrane distillation (DCMD) was applied to the oxidation under pressure (POX) effluent treatment at different feed temperatures (50–70 °C) and recirculation flowrates (0.3–1.5 L/min). Two different commercial membranes made of poly(tetrafluoroethylene) (PTFE) and poly(vinylidenefluoride) (PVDF) were compared, including the contribution of an additional spacer, in terms of distillate recovery rate and retention efficiency. Lower wetting rates were obtained for lower feed temperatures and recirculation flowrate, which allowed for a greater permeate recovery rate. In contrast, an increase in both feed temperature and recirculation flowrate led to lower resistances. Among them, the resistance imposed by the membrane had the highest contribution to mass transfer resistance, whereas fouling resistance had negligible effects. Due to its lower hydrophobicity, PVDF membranes were more subjected to wetting if compared to PTFE membranes. Under the best conditions (PTFE with spacer, feed temperature of 60 °C and 0.3 L/min) the process had an average distillate flux of 6.82 L/m2 h and a permeate recovery rate of 33.91%, without compromising the permeate physicochemical quality. That corresponds to high values of metals and acidy retention, >95.7% and >99.9%, respectively, generating a permeate that can be used directly as reuse water in the mining plant. Regardless of that, both membranes maintained its rejection efficiency and distillate flux after 240 days exposed to the effluent under similar experimental conditions. Moreover, no significant changes were observed in their morphology or structure. Overall, DCMD was considered as a promising alternative for process water reclamation since the final temperature of this effluent can reach up to 80 °C, which corroborates the use of its residual heat as a driving force of DCMD, thus reducing the energy demand for the processing of this effluent. [ABSTRACT FROM AUTHOR]

• Cyanide is poorly removed by adsorption onto metal flocs in chemical coagulation. • Iron electrochemical coagulation leads to a complete cyanide removal. • Formation of soluble iron cyanide complexes allows reducing solution toxicity. • Cyanide solubility decreases by charge neutralization with soluble Al(OH) 3. • Null detection of cyanate or hazardous inorganic chlorine species. In this work, coagulation and electrocoagulation for the removal of cyanide ions contained in synthetic mining wastewater were evaluated paying particular attention to the elucidation of the coagulation mechanisms. Iron and aluminum salts with concentrations ranging from 0.01 to 10 000 mg dm−3 metal were used in chemical coagulation. Experimental data were properly fitted to Freundlich isotherm to elucidate that the main mechanism to remove cyanide during chemical coagulation was adsorption onto coagulant flocs although a maximum cyanide removal percentage of only 25% was attained. Then, electrochemical coagulation with iron and aluminum electrodes was evaluated at 1, 10 and 100 A m−2, obtaining completely different results. Iron electrochemical coagulation leads to the complete cyanide removal regardless of the current density applied, although the TOC removal was much lower than expected. On the contrary, only 60% of cyanide removal was reached by aluminum electrochemical coagulation and its efficiency was found to be highly dependent on the current density applied. Furthermore, no cyanate or hazardous inorganic chlorine species were detected during both electrocoagulation processes. However, chloride was oxidized to hypochlorite and then, it reacted with ammonium ions (contained in mining wastewater or produced by chemical reduction of nitrate by aluminum) to form chloramines. A proposal of coagulation mechanisms during the electrochemical process that explains experimental results was developed which involved the formation of iron-cyanide complexes, charge neutralization, adsorption on a superficially charged metal precipitate and/or enmeshment into a sweep metal floc. [ABSTRACT FROM AUTHOR]

• Pb and Zn can be separately recovered in a BES-assisted electrodeposition system. • A more negative cathodic potential will accelerate the metal recovery. • Deposition of Pb is faster and thus can be recovered first followed by Zn recovery. • 98.5 % Pb and 98.7 % Zn can be selectively recovered at different cathode potentials. • The diffusion process may be a rate limiting step for electrodeposition of metals. Proper treatment of mining wastewaters is critically important to minimize contamination by heavy metals contained in those wastewaters. Herein, a bioelectrochemically-assisted electrodeposition (BES-EDP) system was developed and investigated for selective removal and recovery of Pb and Zn from a mimicked smelting wastewater. It was observed that those two metals were reduced at different cathodic potentials and electrodeposition time. At a cathodic potential of −0.75 V vs. Ag/AgCl, 98.5 ± 1.4 % of Pb was recovered after 10 h of reaction while there was little Zn deposition. Increasing the cathodic potential to −1.2 V could achieve 98.7 ± 0.7 % of Zn with the electrodeposition time of 6 h. The composition of the deposits confirmed the results from solution analysis and metal oxides were also formed during metal reduction. The diffusion impedance was much higher than the charge transfer resistance, suggesting that the diffusion process was a rate limiting step for electrodeposition. The diffusion process was verified by chronoamperometry with a good fit in Cottrell equation. The electrodeposition equilibrium constant k 0 was determined as 3.76 cm s−1. Those results have demonstrated the feasibility of using bioelectricity to assist with selective metal recovery and warrant further investigation of technologies for sustainable management of mining wastewaters. [ABSTRACT FROM AUTHOR]

• Cyanide degrading bacteria (CDB) from various sources were chosen. • CDB ability to degrade FCN in liquid medium was tested and its performance was compared. • Deposit materials in decontaminated liquid medium were characterised. • Possible reuse of deposit materials was revealed. This study reports on the biodegradation of free cyanide (FCN) by cyanide degrading bacteria (CDB) that were isolated from mining wastewater and thiocyanate containing wastewater. The performance of these isolates was compared to cryopreserved CDBs that were used in previous studies. The performance of the isolates to degrade FCN was studied in batch cultures. It was observed that the CDB from the thiocyanate wastewater showed higher biodegradation rates (2.114 g CN−. L−1.O.D 600 nm −1.h−1) compared to the isolates from the mining wastewater. The isolates from the cryopreserved CDBs and from the mining wastewater achieved a biodegradation rate of 1.285 g CN− L−1.O.D 600 nm −1.h−1 and 1.209 g CN−.L−1.O.D 600 nm −1.h−1, respectively. This study demonstrated that the source of the organisms plays a significant role on FCN biodegradation. [ABSTRACT FROM AUTHOR]