Search Results (184)

In this study, we report the development of a novel magnetized coal fly ash-supported nano-silver composite (AgNPs/MCFA) for dual-functional applications in wastewater treatment: the efficient degradation of methyl orange (MO) dye and broad-spectrum antibacterial activity. The composite was synthesized via a facile impregnation–reduction–sintering route, utilizing sodium citrate as both a reducing and stabilizing agent. The AgNPs/MCFA composite was systematically characterized through multiple analytical techniques, including Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and vibrating sample magnetometry (VSM). The results confirmed the uniform dispersion of AgNPs (average size: 13.97 nm) on the MCFA matrix, where the formation of chemical bonds (Ag-O-Si) contributed to the enhanced stability of the material. Under optimized conditions (0.5 g·L⁻¹ AgNO₃, 250 °C sintering temperature, and 2 h sintering time), AgNPs/MCFA exhibited an exceptional catalytic performance, achieving 99.89% MO degradation within 15 min (pseudo-first-order rate constant k_a = 0.3133 min⁻¹) in the presence of NaBH₄. The composite also demonstrated potent antibacterial efficacy against Escherichia coli (MIC = 0.5 mg·mL⁻¹) and Staphylococcus aureus (MIC = 2 mg·mL⁻¹), attributed to membrane disruption, intracellular content leakage, and reactive oxygen species generation. Remarkably, AgNPs/MCFA retained >90% catalytic and antibacterial efficiency after five reuse cycles, enabled by its magnetic recoverability. By repurposing industrial waste (coal fly ash) as a low-cost carrier, this work provides a sustainable strategy to mitigate nanoparticle aggregation and environmental risks while enhancing multifunctional performance in water remediation. Full article

Reverse osmosis (RO) concentrated water can be effectively treated with catalytic ozone oxidation technology, an effective advanced oxidation process. In order to provide a thorough reference for the safe treatment and reuse of RO concentrated water, this paper examines the properties of RO concentrated water, such as its high salt content, high levels of organic pollutants, and low biochemistry. It also examines the mechanism of its role in treating RO concentrated water and combs through its applications in municipal, petrochemical, coal chemical, industrial parks, and other industries. The study demonstrates that ozone oxidation technology can efficiently eliminate the organic matter that is difficult to break down in RO concentrated water and lower treatment energy consumption; however, issues with free radical inhibitor interference, catalyst recovery, and stability still affect its use. Future research into multi-technology synergistic processes, the development of stable and effective non-homogeneous catalysts, and the promotion of their use at the “zero discharge” scale for industrial wastewater are all imperative. Full article

This study explores the optimisation of nozzle design for external twin fluid, single-stage atomisation in handling high-viscosity, shear-thinning polydimethylsiloxane (PDMS). A single PDMS grade was employed and atomised using unheated sonic air and the viscosity was varied by the fluid temperature. A systematic experimental approach was used, varying nozzle geometry—specifically apex angle, gas nozzle diameter, and number of gas nozzles—to identify the optimal nozzle configuration (ONC). The spray qualities of the nozzle configurations were evaluated via high-speed imaging at 75,000 FPS. Shadowgraphy was employed for the optical characterisation of the spray, determining the optimal volumetric air-to-liquid ratio (ALR), a key parameter influencing energy efficiency and operational cost, and for assessing droplet size distributions under varying ALR and viscosity of PDMS. The ONC yielded a Sauter mean diameter $d_{32}$ of 570 × 10⁻⁶$\mathrm{m}$, at an ALR of 8532 and a zero-shear viscosity of 15.9 $\mathrm{Pa}$ $\mathrm{s}$. The results are relevant for researchers and engineers developing twin fluid atomisation systems for challenging industrial fluids with similar physical properties, such as those in wastewater treatment and coal–water slurry atomisation (CWS). This study provides design guidelines for external twin fluid atomisers to enhance atomisation efficiency under such conditions. Full article

Mine water treatment and emissions have become important factors that restrict the comprehensive benefits of coal enterprises and local economic development, and the use of the deep well recharge method can address the specific conditions of mine surge water. This paper takes the actual situation of coal mine water treatment as an example and innovatively carries out dynamic tests for the Ordovician limestone aquifers deep in the mine. Intermittent reinjection test shows that under the same reinjection time, the water level recovery rate during the intermittent period is fast at first and then slow. Moreover, the recovery speed of the water level buried depth slows down with the increase in the reinjection time, which reveals the characteristics of the water level rising rapidly and recovering quickly during the reinjection of the reservoir. The average formation water absorption index is 420.81 m³/h·MPa. The water level buried depth of the long-term reinjection test showed three stages (rapid rise, slow rise, and stable stages), and the water level buried depth was raised to 1.52 m at its highest. Monitoring data from the surrounding 5 km area showed that reinjection did not affect aquifer water levels, verifying the excellent storage capacity of the deep Ordovician fissure-karst aquifer. The variability of well loss under pumping and injection conditions was comparatively analyzed, and the well loss produced by the recharge test was 4.06 times higher than that of the pumping test, which provided theoretical support for the calculation of hydrogeological parameters to eliminate the influence of well loss. This study deepens the understanding of Ordovician limestone aquifers in deep mine water, providing a reference for cheap mine water treatment and sustainable groundwater management in similar mine areas. Full article

Industrial and urban activity has inevitably changed the water environment and caused significant impacts on water resources’ quality and quantity. The identification of related impacts is particularly important in the context of increasing water shortages due to climate change. Overlapping industrial impacts and drought occurrence have resulted in the long-lasting deterioration of surface water status. Therefore, the mitigation of negative impacts is crucial for relevant and sustainable water management in river basins. One of the most impactful branches of industry is underground coal mining, which requires dewatering deposits and excavations. Mine waters discharged into rivers have induced significant increases of salinity, while urban wastewaters have increased biogenic contamination in surface waters. Sustainable development goals require water protection, energy transition, and circularity; therefore, coal will be repurposed in favor of alternative sources of energy. The phasing out of coal and cessation of dewatering of mines would rapidly reduce mine waters’ impact on the environment. However, in heavily industrialized urban basins, the share of natural waters in river flows is exceptionally low—due to significant and long-lasting transformations, industrial and urban wastewaters are the main constitutive components in certain river hydrological regimes. The case study of Bytomka in the Upper Silesian Coal Basin, Southern Poland is a vivid example of a river basin significantly impacted by urban and industrial activity over a long-term period. The Bytomka River’s water status and the development of its watershed area is an example of complex and overlapping impacts, wherein sustainable water management requires proper recognition of prevailing factors such as mine water discharges, climate change and drought periods, wastewater impacts, and urbanization of the water basin area. The presented study reveals key findings showing that future coal mine closures would result in significant water resource shortages due to a reduction of mine water discharges, significant biogenic (N and P) pollution increases, and hazards of harmful algal blooms. Therefore, there is an urgent need to increase the retention potential of the watershed, use nature-based solutions, and mitigate negative impacts of the coal mining transition. The increase in treatment capability of industrial wastewater and sewage discharge would help to cope with the natural water vulnerability induced by the impacts of climate change. Full article

As coal’s share in primary energy consumption wanes, the annual increase in abandoned coal mines presents escalating safety and environmental concerns. This paper delves into cutting-edge models and attributes of integrating pumped storage hydropower systems with subterranean reservoirs and advanced wastewater treatment facilities within these decommissioned mines. By utilizing the expansive underground voids left by coal extraction, this method aims to achieve multifaceted objectives: efficient energy storage and generation, reclamation of mine water, and treatment of urban sewage. This research enhances the development and deployment of pumped storage technology in the context of abandoned mines, demonstrating its potential for fostering sustainable energy solutions and optimizing urban infrastructure. This study not only facilitates the progressive transformation and modernization of energy cities but also provides crucial insights for future advances in ecological mining practices, energy efficiency, emission mitigation, and green development strategies in the mining industry. Full article

Zero-liquid discharge (ZLD) of desulfurization wastewater from coal-fired power plants is a critical challenge in the thermal power industry. Flash evaporation technology provides an efficient method for wastewater concentration and the recovery of high-quality freshwater resources. In this study, numerical simulations of the high-temperature and high-pressure spray flash evaporation process within a flash tank were conducted using the Discrete Phase Model (DPM) and a self-developed heat and mass transfer model for superheated droplets under depressurization conditions. The effects of feedwater temperature, pressure, nozzle spray angle, and mass flow rate on spray flash evaporation characteristics were systematically analyzed. Key findings reveal that (1) feedwater temperature is the dominant factor, with the vaporization rate significantly increasing from 19.78% to 55.88% as temperature rises from 240 °C to 360 °C; (2) higher pressure reduces equilibrium time (flash evaporation is complete within 6 ms) but shows negligible impact on final vaporization efficiency (stabilized at 33.93%); (3) increasing the spray angle provides limited improvement to water recovery efficiency (<1%); (4) an optimal mass flow rate exists (0.2 t/h), achieving a peak vaporization rate of 42.6% due to balanced evaporation space utilization. This work provides valuable insights for industrial applications in desulfurization wastewater treatment. Full article

Oil spills in inland rivers pose a significant threat to the surrounding environment, and the emergency response differs greatly from that in ocean or coastal areas. In this study, we focused on several commonly used emergency water treatment strategies in China’s inland oil spills, as well as the spilled washing oil in a serious accident case. We investigated the changes in oil-related chemical components before and after water treatment using GCxGC-TOF MS (Comprehensive Two-dimensional Gas Chromatography Time of Flight Mass Spectrometer). We tracked the shifts of microbial communities in the microcosms incubated with clean river water, simulated oil-contaminated water, and the treatment effluent. The results revealed that typical components, especially nitrogen-containing heterocyclic compounds, had different removal efficiencies among treatments. The diversity, composition, and potential functions of microbial communities responded differently to the treatments, and could be related to various substances, including PAHs (polycyclic aromatic hydrocarbons) and heterocyclic compounds. A few genera, such as SC-I-84, exhibited a high correlation with washing oil-related components and could serve as an indicator in such an oil spill emergency response. Our findings indicated that simply using petroleum oil or PAHs to evaluate oil spills was likely to underestimate the ecological impact, especially when the spilled substances were coal chemical products widely used in China. This will provide an important scientific basis for decision-making and strategy evaluation in emergency responses to inland oil spills. Full article

The ubiquity of diclofenac (DCF) in the environment has raised significant concerns. Diclofenac is a non-steroidal anti-inflammatory drug that has been found in various environmental matrices at minimum concentrations that are harmful to aquatic and terrestrial organisms. Traditional wastewater treatment plants (WWTPs) are not fully equipped to remove a range of pharmaceuticals, and that explains the continued ubiquity of DCF in surface waters. In this study, an Fe₃O₄/SiO₂ nanocomposite prepared from acid mine drainage and coal fly ash was applied for the removal of DCF from wastewater. Major functional groups (Si–O–Si and Fe–O) were discovered from FTIR. TEM revealed uniform SiO₂ nanoparticle rod-like structures with embedded dark spherical nanoparticles. SEM-EDS analysis discovered a sponge-like structure fused with Fe₃O₄ nanoparticles that had significant Si, O, and Fe content. XRD demonstrated the crystalline nature of the nanocomposite. The surface properties of the nanocomposite were evaluated using BET and were 67.8 m²/g, 0.39 cm³/g, and 23.2 nm for surface area, pore volume, and pore size, respectively. Parameters that were suspected to be affecting the removal process were evaluated, including pH, nanocomposite dosage, and sample volume. The detection of DCF was conducted on high-performance liquid chromatography with diode-array detection (HPLC-DAD). Under optimum conditions, the adsorption process was monolayer, and physisorption was described using the Langmuir and Dubinin-Radushkevich (D-R) isotherm models. The kinetic data best fitted the pseudo-first order kinetic model, indicating a physisorption adsorption process. The thermodynamic experimental data confirmed that the adsorption process was spontaneous. The results obtained from real water samples showed 95.28% and 97.44% removal efficiencies from influent and effluent: 94.83% and 88.61% from raw sewage and final sewage, respectively. Overall, this work demonstrated that an Fe₃O₄/SiO₂ nanocomposite could be successfully prepared from coal fly ash and acid mine drainage and could be used to remove DCF in wastewater. Full article

Deep coalbed methane (CBM) reservoirs have the characteristics of low permeability, low porosity, and low water saturation, which easily experience wellbore instability due to drilling fluid, severely affecting drilling safety. Based on the physical property analysis of coal samples, the wellbore instability mechanism of the deep CBM reservoir was investigated by multiple methods. It was found that the wellbore instability is mainly caused by drilling fluid intrusion and the interaction between drilling fluid and coal formation; the fracture pressure of coal after immersion decreased from 27.4 MPa to 25.0 MPa because of the imbibition of drilling fluid. A novel nano-plugging agent with a size of 460 nm was prepared that can cement coal particles to form disc-shaped briquettes with a tensile strength of 2.27 MPa. Based on that, an effective anti-collapse drilling fluid for deep coal rock reservoirs was constructed, the invasion depth of the optimized drilling fluid was only 6 mm. The CT result shows that the number of fractures and pores in coal rock significantly reduced after treatment with the wellbore-stabilizing drilling fluid; nano-plugging anti-collapse agent in drilling fluid can form a dense layer on the coal surface, and then the hydration swelling of clay in the wellbore region can be effectively suppressed. Finally, the drilling fluid in this work can achieve the purpose of sealing and wettability alternation to prevent the collapse of the wellbore in the deep coal reservoir. Full article

Coal dust seriously affects the underground working environment. The current water-spray dust reduction technology uses a large amount of water and has a poor effect on coal dust with poor wettability. This study proposed a clean and sustainable technology using plasma-activated water (PAW) to alter the wettability of coal dust and improve its dust control effect. The PAW was prepared and its physical and mathematical properties were tested by a device designed in-house. The influence of PAW on the wettability of coal dust was determined by the coal dust contact angle experiments. The effect of PAW on the surface morphology of coal dust was analyzed by a scanning electron microscope. The effect of PAW on the pore structure of coal dust was analyzed through the specific surface area and pore size experiments. The results showed that PAW contained a large number of active substances such as H₂O₂, NO₃⁻, and NO₂⁻, showing strong and stable oxidation. PAW could significantly reduce the instantaneous contact angle of coal dust, and the higher the degree of coal dust metamorphism, the more significant the reduction effect. The surface morphology, pore volume, specific surface area, and fractal dimension of the coal dust were significantly changed after PAW treatment. PAW could transform the non-uniform three-dimensional spatial distribution of the coal dust surface into an approximate two-dimensional planar distribution, thus enhancing the wettability of the coal dust. With the increase in PAW ionization intensity, the contact angle of long-flame coal was negatively correlated with the mesoporous pore volume. The contact angle of gas coal was negatively correlated with the micropore volume and micropore specific surface area, and was positively correlated with the mesopore volume. The contact angle of meager lean coal was positively correlated with the macropore specific surface area. The surface morphology, pore volume, specific surface area, and fractal dimension changes in coal dust treated with PAW can reveal the wettability enhancement mechanism to some extent. The results of the study can provide pre-theoretical guidance for the field application of PAW coal mine dust reduction technology. Full article

Hydraulic fracturing is an effective method for enhancing coalbed methane (CBM) recovery. The injected fluids affect the chemical and physical structures of coal, resulting in diverse stimulation effects. While most current research primarily focuses on alterations in pore-fracture structures, few studies have examined or compared the changes in chemical structures during the fracturing process. This study presents a comparative analysis of the effects of five types of pre-fracturing fluids—slick water, acid solutions, and oxidant solutions—on coal, with the aim of identifying the similarities and differences in how these fluids modify the chemical structure of coal. The results indicate that, after being treated by five pre-fracturing fluids, the aromaticity index (I) increased, and the degree of aromatic condensation polymerization (DOC) decreased. The length of the aliphatic chain (L) increased after being treated by PAM but decreased after being treated by acids and oxidizers. Additionally, the graphitization (g) of all coal samples increased. Among the treatments, the combined acid system of hydrochloric acid (HCl) and hydrofluoric acid (HF) demonstrated a more pronounced effect on enhancing aromaticity and graphitization of the microcrystalline structure compared to HCl alone. Sodium hypochlorite (NaClO) had the most significant impact on the ordering of the macromolecular structure, while hydrogen peroxide (H₂O₂) exerted the most pronounced effect on the graphitization of the microcrystalline structure. These findings contribute to a deeper understanding of the interaction mechanisms between fracturing fluids and coal, providing theoretical support for the efficient development of CBM. Full article

Coal gangue (CG) has become a critical environmental challenge in China, with nearly one billion tons produced annually. To address this challenge while simultaneously supplementing soil resources during mine ecological restoration, a novel process is proposed to convert CG into CG-based artificial soil (CGAS) using a microbial treatment method. This study examined the effects of local microbial agents (LMAs), commercial microbial agents (CMAs), and fly ash (FA) on key soil properties of CGAS, such as organic matter (OM) content, humic acid (HA) content, and water-holding capacity. Additionally, the mechanisms underlying aggregate formation in CGAS were investigated. The results showed that the synergistic effect of LMAs and FA significantly enhanced the essential quality properties of CGAS. In particular, the HA content increased by 2.06 times compared with untreated CG, the proportion of water-stable macroaggregates increased to 11.46%, and the bulk density decreased by 39.71%, achieving an optimal level of 1.30 g/cm³. Analysis of phase compositions, surface functional group characterization, and microstructural examination indicated that organic binders such as HA, inorganic binders such as calcium carbonate and gypsum, and the bonding effect of spherical particles of FA played significant roles in forming a stable and healthy soil structure in CGAS. Full article

Zero Liquid Discharge (ZLD) is a wastewater management strategy that eliminates liquid waste while maximizing water use efficiency. This article reviews the primary ZLD technologies used for desulfurization wastewater (DWW) treatment in coal-fired power plants. These technologies include the thermal process and the membrane process. The thermal process includes “concentrated crystallization” technology and “gas evaporation and drying” technology. The paper also highlights recent advances in membrane technology for power plant wastewater treatment. The advantages and limitations of each technique are discussed. Membrane technology is considered a promising solution for wastewater recycling, while thermal technology offers easy operation and maintenance without the need for pretreatment. Finally, the paper outlines possible future directions for the treatment of DWW. Full article

Coal mine gangue cementation filling technology has increasingly become an effective and major means of dealing with “coal mining under buildings, railways, and bodies of water” and other complex hard-to-mine coal seams; but also, an important part of a large number of treatments of coal gangue stockpiled on the ground is to realize the green mining of coal mines. Coal mine cement filling often contains gangue particles with particle sizes larger than 15 mm; however, the viscometer and rheometer currently used at home and abroad are unable to accurately measure the rheological parameters of the slurry containing large-particle-sized gangue. In order to accurately measure the rheological parameters of slurry containing large-sized gangue particles combined with the site filling materials, the torque values obtained on the mixing blades at different speeds were generated by the combined action of the slurry between the blade side edge and the mixing drum wall, as well as the slurry between the blade lower edge and the mixing drum bottom. A new type of gangue slurry rheometer was developed. The new type of gangue slurry rheometer mainly included components such as the power system, sensing system, mechanical system, and other auxiliary units. Finally, using Fluent software ANSYS2023 to numerically simulate the fluidity of the slurry under the same conditions, the results obtained after the calculation and the test results showed that the error was within a reasonable range, indicating the correctness of the test principles of the new gangue slurry rheometer and the effectiveness of the instrument. This research offers new insights for accurately measuring the rheological parameters of particles with large sizes. Full article