Pollution Remediation Research Articles

Identifying potential introduced and natural sources of pollution in Delaware watersheds

ABSTRACT Managing water quality with microbial impairment caused by Enterococcus poses unique challenges regarding the determination of fecal host origin. Most water monitoring is performed based on Enterococcus counts that neither detect the location of the introduction of pollution nor identify the type of contaminating Enterococcus . The use of sequenced-based microbial source tracking could allow for identification of fecal origin and potential remediation of pollution. The state of Delaware has numerous waterways with high microbial impairment from unknown sources, so we used sequence-based microbial source tracking to investigate potential microbial pollution in three watersheds with significant variation in land use and population density. In this study, we use a 16S rRNA sequence reference library of microbial communities from relevant fecal sources (wild animal, domestic animal, sediment, and septic/wastewater) to determine the most likely sources of microbial impairment in three Delaware watersheds. This study assigned sources of microbial contamination to mostly human-related sources (septic and wastewater) or unknown sources indicating that waste infrastructure may have a larger influence on microbial community structure in Delaware watersheds than previously considered. Our results suggest that long-term source tracking is valuable for ruling out native or domesticated animals as contributors to water pollution. IMPORTANCE Traditional microbial pollution monitoring utilizes specific fecal indicator bacteria that need to grow in the laboratory for detection. Here, we show the use of sequence information from whole microbial communities and an expanded reference library in microbial source tracking. Expanding the host detection range by including the whole microbial community may allow for a wider range of potential fecal origin identification even when specific fecal indicators are absent or in low concentration. We show that many Delaware waterways bear the signature of human influence compared to natural sources. In addition, the robust reference library built in this study can be used to conduct source tracking studies in the mid-Atlantic USA.

Arsenic Enhances the Degradation of Middle-Chain Petroleum Hydrocarbons by Rhodococcus sp. 2021 Under Their Combined Pollution

The efficient and green remediation of petroleum hydrocarbon (PH) contamination has emerged as a viable strategy for environmental management. Here, we investigated the interaction between arsenic and PH degradation by Rhodococcus sp. 2021 under their combined pollution. The strain exhibited disparate responses to varying concentrations and valences of arsenic. The elevated concentration of arsenic (>100 mg/L) facilitated the degradation of PHs, and there was a positive correlation between arsenic-promoted degradation of PHs and their carbon-chain length. The degradation of PHs changed with arsenic conditions as follows: trivalent arsenic groups > pentavalent arsenic groups > arsenic-free groups (control). Arsenite and arsenate significantly promoted the gene expression of arsenic metabolism and alkane degrading. But unlike arsenite, arsenate also significantly promoted the gene expression of phosphate metabolism. And arsenite promoted the up-regulation of the expression of genes involved in the process of PHs oxidation and fatty acid oxidation. These results highlight the potential of Rhodococcus sp. 2021 in the remediation of combined total petroleum hydrocarbon (TPH) and heavy metal pollution, providing new insights into the green and sustainable bioremediation of combined pollution of organic matters such as PHs and heavy metals/heavy metal-like elements such as arsenic.

Heavy Metal Remediation Using Phosphate-Solubilizing Fungi: From Bioprocess to Application

Heavy metal pollution has been a major environmental issue in recent years, seriously threatening land, water sources, agriculture, and human health. The remediation of heavy metal pollution has been a continuously vital issue for current research. Bioremediation is an effective and cost-efficient approach to reduce heavy metal toxicity. Phosphate-solubilizing fungi (PSF) have shown promise in heavy metal bioremediation due to their high tolerance and activity levels. However, the full potential of PSF in bioremediation needs further exploration. PSF activity, metabolite production, and environmental conditions can influence their efficiency in remediating heavy metals. These factors play a critical role in the practical application of PSF and necessitate improvement pathways. This article reviews potential strategies to enhance heavy metal remediation using PSF and optimizing bioprocesses and applications.

Protection of water resources from agricultural pressures: Embracing different knowledge domains in governance approaches

AbstractThe remediation of nitrate and pesticide pollution from agriculture in drinking water resources has manifested itself as a complex and multifaceted challenge in Europe and in other continents. Addressing agricultural pollution in water resources requires cross‐sectoral approaches. The EU Water Framework Directive aims to build bridges among these sectors, but the often sectoral implementation by Member States prevents its potential from being fully explored. This study aims to contribute to the body of interdisciplinary knowledge on the driving forces towards water quality improvement from agricultural pollution by case study research in five European countries in an interdisciplinary setting. The cases have shown that the added value of voluntary practices is considerable for creating shared ambitions but limited for actual water quality improvement. Implementation of strategies should be supported by practical guidance and monitoring of outcomes that enables compliance testing and refines simulation models for the formulation of follow‐up actions. Dynamic interactions among the knowledge domains, for example, social‐economic context, the legal framework, and the state of the water system, help to identify necessary actions at the different stages of the policy cycle. Especially in the implementation, monitoring, evaluation, and adaptation stage of the policy cycle, there is a need for further studies in order to improve effectiveness, for example on the role of monitoring and evaluation, licensing, and the issue of scale in cross‐sectoral approaches.

Studying the properties of green synthesized silver oxide nanoparticles in the application of organic dye degradation under visible light.

In present study the green synthesis of silver oxide nanoparticles has been effectively achieved using novel plant extract Phragmanthera Macrosolen. This method provides sustainable alternative for nanoparticle synthesis, demonstrating the potential of Phragmanthera Macrosolen as a reducing and stabilizing agent in the production of Ag2O NPs. The synthesized nanoparticles were characterized for their structural, morphological, and optical properties, confirming their successful formation and potential applications in various fields. The effects of different pH values and annealing temperature of the samples on the properties of Ag2O NPs formations, as well as photo-catalytic activities towards Toluidine Blue dye degradations, were studied. Powder XRD reveals that the crystallite natures of Ag2O NPs a long with crystalline size ranges from 25.85 to 35.90nm. FIB-SEM and HR-TEM images displayed that the Ag2O NPs as spherical shapes. UV-vis spectroscopy displayed that Ag2O NPs belong to a direct-band gap of 2.1-2.6eV. FTIR- study shown that the green synthesized Ag2O NPs may be steadied via the interfaces of -OH as well as C = O groups in the carbohydrate, flavonoid, tannin, as well as phenolic acid existing in P. macrosolen L. leaf. The chemical states, electron-hole recombinations and purity of Ag and O in the synthesized Ag2O NPs were confirmed through X-ray Photoelectron Spectroscopy (XPS) and PL analysis respectively. Fascinatingly, the synthesized Ag2O NPs at pH 12 displayed high photo-catalytic degradations for TB dyes. The photo-catalytic degradations of the TB dyes were monitored spectro-photo-metrically in wave-length ranges of 200-900nm, as well as high efficiency (98.50%) with half-life of 9.5798min and kinetic rate constant of 0.07234min-1, was obtained after 45min of reactions. From this study, it can be concluded that Ag2O NPs synthesized from Phragmanthera Macrosolen aqueous extract are promising in the remediation of environmental pollution and water treatment. In this light, the study reports that Phragmanthera Macrosolen green synthesis of Ag2O NPs can effectively address environmental pollution in cost-effective, eco-friendly, and sustainable ways.

Environmental Factors in Oryctes rhinoceros (Coleoptera: Scarabaeidae) Breeding

ABSTRACTThe Oryctes rhinoceros (Scarabaeidae: Coleoptera) is a common coleopteran insect in tropical and subtropical areas with many potential uses. Its larvae are commonly found in dead coconut trees and hay piles in the wild and are widely distributed in the northern hemisphere. This study investigates the environmental factors influencing the growth of Oryctes rhinoceros beetle larvae and provides valuable insights into their breeding conditions versus their potential applications. The research examined three key affecting factors of larval development over time, namely, moisture content, growth space and soil content. Results of a pretest run revealed that moisture content, but not the soil content, affected the larval survival greatly. A reasonable confinement on feed moisture (i.e., 30%–60%) was included in the later conducted three‐factor factorial experiment. At last, results of the factorial run suggested that: (1) for a consistent and massive larval breeding, environmental factors, setting moisture content at 60%, larval space at 100 cm3/larva and no soil addition, are deemed appropriate, (2) for nutritional purpose, setting moisture content at 60%, larval space at 300 cm3/larva and no soil addition are recommended, and (3) for soil pollution remediation, setting moisture content at 60%, larval space at 100 cm3/larva and a soil‐to‐feed (S/F) ratio of 2:1 is concluded. This study marks the first engineering breeding exploration of Oryctes rhinoceros larvae, offering practical recommendations for various research purposes and applications.

Sulfate-driven microbial collaboration for synergistic remediation of chloroethene-heavy metal pollution

The treatment of heavy metal(loid) (HM) composite pollution has long posed a challenge for the bioremediation of organohalide-contaminated sites. Given the prevalent cohabitation of sulfate-reducing bacteria (SRB) with organohalide-respiring bacteria (OHRB), we proposed a sulfate-amendment strategy to achieve synergistic remediation of trichloroethene and diverse HMs [50μM of As(III), Ni(II), Cu(II), Pb(II)]. Correspondingly, 50–75 μM sulfate was introduced to HM inhibitory batches to investigate the enhancement effect of sulfate amendment on bio-dechlorination. Dechlorination kinetics and MATLAB modeling indicated that sulfate amendment comprehensively improved the reductive dechlorination performance in the presence of As(III), Ni(II), Pb(II) and mixed HMs, while no enhancement was observed under Cu(II) exposure. Additionally, sulfate introduction effectively accelerated the detoxification of Ni(II), Pb(II), Cu(II), and As(III), achieving removal efficiencies of 76.87 %, 64.01 %, 86.37 %, and 95.50 % within the first three days, respectively. Meanwhile, propionate dynamics and acetogenesis indicated enhanced carbon source and e-donor supply. 16S rRNA gene sequencing and metagenomic analysis results demonstrated that HM sequestration was accomplished jointly by SRB and HM-resistant bacteria via extracellular precipitation (metal sulfide) and intracellular sequestration, while their contribution depended on the specific coexisting HM species present. This study highlights the critical role of sulfate in the concurrent bioremediation of HM-organohalide composite contamination and provides insights for developing a cost-effective in-situ bioremediation strategy.

Phenyl-C61-butyric acid methyl ester (PCBM) Nanoparticle Mediated Boasting of Photoelectrochemical and Photocatalytic Properties of Bismuth Vanadate/lead sulphide (BiVO4/PbS) Composite Thin-Film

This work delineates the fabrication and characterization of BiVO4/PbS and BiVO4/PCBM/PbS-based composite heterostructure for visible-light-driven applications, such as pollution remediation, photoelectrochemistry (PEC), and applied bias to photoelectrochemical hydrogen generation efficiency (ABPE). The heterostructured composite was synthesized by a combination of Spin coating (for bismuth vanadate - BiVO4 thin film fabrication and PCBM deposition), and Successive Ionic Layer Absorption and Reaction -SILAR (for lead sulphide - PbS deposition) method and characterized using UV-visible Spectroscopy, time-resolved photoluminescence spectroscopy (TRPL), field emission scanning electron microscope (FESEM), X-ray diffraction (XRD), and photoelectrochemistry (PEC) analysis (PEC). The key benefit of incorporation of PCBM nanoparticles in BiVO4/PCBM/PbS was realized through 1) ∼ 70% improvement in the photocurrent density during electrochemistry analysis, 2) ∼ 2.3 times enhancement in ABPE, and 3) ∼ 43% enhancements in ‘rate constant’ towards photocatalytic (methylene blue) degradation compared to BiVO4/PbS. The work shows the benefits of the PCBM-conductive carbon-based electron transport layer as a bridge between two inorganic semiconductors (BiVO4 and PbS) towards enhancing fast electron separation and transport at the interface during visible light irradiation.

Assessment of Cerium Adsorption Potential of Phosphoric acid Activated Biochar in Aqueous System: Modelling and Mechanistic Insights

Cerium pollution in waterbodies by improper industrial waste disposal is a major concern due to its detrimental impacts on the environment. Therefore, treatment of cerium-contaminated water is inevitable. Hence, this study is focused on the remediation of cerium pollution using phosphoric acid-activated biochar (PPMB) as an adsorbent, synthesized upon pyrolytic activation of palmyra palm male flower-based pristine biochar (PMFB) with H3PO4 at 500°C. The physico-chemical surface properties of PMFB and PPMB were evaluated through various microscopic and spectroscopic analyses. The key parameters such as biochar dosage, pH, temperature, contact time and initial cerium concentration were optimized as 0.5 g/L, 5.0, 303 K, 180 min and 50 mg/L respectively via batch adsorption. Pseudo-second order kinetic and Toth isotherm are the best-fitted models. The thermodynamic parameters including ΔG◦ (-30.4707±0.7618 kJ/mol at 303 K), ΔH◦ (16.1499±0.78 kJ/mol), and ΔS◦ (153.617±3.8404 J/mol/K) conveying that cerium adsorption onto PPMB was spontaneous, endothermic, and highly disordered at PPMB-bulk adsorption medium interface. Precipitation, electrostatic attraction, and surface complexation are predicted to be the predominant mechanisms for the chosen PPMB-cerium adsorption system. Moreover, cerium phytotoxicity on Vigna radiata explains the real-time applicability and feasibility of cerium adsorption using PPMB. Thus, the key findings of this study specified that the higher adsorption capacity of PPMB (141.3484±6.9856 mg/g) contributed by the incorporated phosphate groups, predominant mesoporosity, SSABET of 230.559 m2/g and anionic surface at a wider pH range (pH>3.08) make PPMB as efficient, economically feasible and environmentally friendly adsorbent for cerium adsorption in aqueous system.

Microbial remediation of heavy metal-polluted water

Heavy metal pollution in water has become a global environmental problem, threatening aquatic ecosystems and human health. Physical and chemical methods can effectively remove heavy metal pollutants, while their applications are limited due to the high costs, complex operation, and susceptibility to secondary pollution. Bioremediation is the most promising method for eliminating toxic pollutants. Microorganisms including bacteria, fungi, and algae can convert toxic heavy metals into less toxic forms, which has become an effective and environmentally friendly solution for the remediation of heavy metal pollution in water environments. This paper expounds the toxicity and mechanism of heavy metal pollution, microbial remediation mechanisms, and primary microbial remediation strategies, providing a reference for the removal or reduction of metal pollutants in water environments as well as the development of related technologies.

Advances in photocatalytic degradation of tetracycline using graphene-based composites in water: a systematic review and future directions.

In this study, a comprehensive systematic review was conducted to better recognize the applicability of graphene-based photocatalytic processes for the degradation of tetracycline (TC) from water. A broad search strategy was developed for English language articles available in PubMed, Scopus, and Web of Science. The effect of parameters such as pH, TC concentration, photocatalyst dose, radiation source intensity, and the effect of graphene on the process, kinetics, and reuse of the photocatalyst were investigated. A total of 63 out of a possible 3498 retrieved records met inclusion criteria. The results showed that most related studies have increased since 2019. About 46.7% of the articles showed 90-100% TC removal efficiency and 59.52% of the studies had optimal pH equal to 5 and 6. Also, the widespread use of visible light had a significant trend. The effect of the dose of graphene in the catalyst was one of the most important and effective factors on the process; hence, the difference in efficiency with and without graphene was completely evident. This review indicated that the presence of graphene has been able to have a positive effect on increasing the efficiency of oxidation processes, and it can be used for environmental pollutants remediation.

Green Engineered CuO/SnO2/HNT Composites: Illuminating the Photocatalytic Path for Organic Pollutant Remediation and Zebrafish Embryo Toxicity Evaluation.

Photocatalysis stands out as a promising technique for treating organic contaminants, yet the quest for visible light active composite materials, crafted through cost-effective, eco-friendly, and uncomplicated processes, poses formidable challenges. Here, we introduce a successful endeavor, the synthesis of a CuO/SnO2 (CS) composite via a microwave method, employing Carissa edulis fruit extract as a reducing as well as capping agent. Various loadings of CS-HNT composites were prepared by ultrasonically incorporating CS onto nanotubular halloysite (HNT) clay. Employing a suite of types of characterization, including XRD, XPS, FT-IR, FE-SEM, HR-TEM, ζ potential, UV-vis-DRS, TGA, BET, and EIS, we meticulously explored the morphology, structure, stability, surface area, electrochemical, and optical properties of the developed CS-HNT composites. HR-TEM observations unveiled the formation of a heterojunction between cubic CuO and spherical SnO2 on the HNT clay surface. Optical and EIS analysis highlighted that the 20CS-HNT composite displayed significant absorption in the visible region, efficient electron-hole pair separation, and enhanced interfacial charge transport relative to other loadings. Photocatalytic evaluations and optimization studies revealed that the 20CS-HNT photocatalyst achieved notable removal efficiencies, eliminating 85% of Congo red (CR) and 80% of tetracycline (TC) within 90 min and 74% of ATZ in 3 h under visible light conditions. Scavenging investigations, the fluorescence probe method, and a NBT transformation study underscored the pivotal roles of hydroxyl and superoxide radicals in pollutant removal. The reusability trials highlighted the exceptional stability and recyclability of the photocatalyst, even after five cycles. In addition, zebrafish embryo toxicity tests revealed improved survival and hatching rates in photocatalyst-treated samples compared to those of controls. Moderate toxicity was observed in treated TC, while the treated CR sample showed non-lethal toxicity. In essence, this study unveils a straightforward and efficacious approach for developing photocatalysts for large-scale wastewater treatment. Furthermore, it proposes the adoption of safe clay-based bimetal oxide photocatalysts in diverse environmental applications.

Study on the remediation of groundwater nitrate pollution by pretreated wheat straw and woodchips

Groundwater nitrate contamination poses a threat to both the ecological environment and human health. This study investigated the potential of using saturated Ca(OH)2 to pretreat wheat straw and woodchips, aiming to enhance their efficacy as carbon sources for denitrification. The optimization of pretreatment conditions, and the elucidation of underlying mechanisms were explored. The pretreatment process involved the dissolution of lignin and hemicellulose, exposure of the cellulose structure, reduction of hydrogen bonds within cellulose, hydrolysis of polymerized cellulose, and the formation of cracks and hierarchical structures on the surface of the carbon source. These alterations improved the attachment and utilization of microorganisms. The maximum enzymatic reducing sugar yields for wheat straw and woodchips were achieved at solid-liquid ratios of 1:40 and soaking times of 5 and 2 days, respectively. The response surface predicted the optimal pretreatment conditions for wheat straw to be a solid-liquid ratio of 1:88.1 and a soaking time of 8.2 h. Alkaline treatment increased the denitrification rate of woodchips by fivefold and prevented the initial organic matter leaching rate of wheat straw, thereby reducing the risk of secondary pollution. The predominant microbial communities in all samples exhibited functions related to lignocellulose degradation and denitrification. The community composition of solid-phase carbon sources was found to be richer than that of liquid-phase carbon sources, and the pretreatment increased the abundance of lignocellulose degradation and denitrification functional microorganisms. The pretreatment liquid of wheat straw achieved the highest denitrification rate constant (0.43 h−1). Our result validated the feasibility of using the pretreatment liquid as a denitrification carbon source and presenting a novel approach for waste resource utilization.

Computational insights into pectin and chitosan-enhanced MOFs: A green pathway for pollutant remediation

Water contamination with dyes and pharmaceuticals is a major threat to ecological and human well-being. This study highlights the importance of using molecular simulations in designing and predicting the performance of novel adsorbents for wastewater treatment. The research explores the potential of biodegradable polymers like Pectin (PE) and oxidized Chitosan (OCN) in functionalizing a metal-organic framework (MOF) known as UO-66 (Zr) (UO). By incorporating these functional groups, the study aims to improve the adsorption efficiency of UO towards rhodamine B (RHOB, a dye pollutant) and Losartan (LOSA, a pharmaceutical pollutant). Firstly, density functional theory (DFT) calculations were employed to inspect the structures of both pollutants and the modified adsorbents. Subsequently, the research investigated the adsorbents’ various physicochemical characteristics, including fractional free volume, glass transition temperature, and mechanical properties. Finally, molecular dynamics (MD) and Monte Carlo (MC) simulations were accomplished to evaluate the adsorption behaviour of the pollutants on various UO forms (pristine, PE-functionalized, and OCN-functionalized). The study found that all adsorbents showed strong adsorption capabilities, with adsorption energies ranging from −3500 to −4500 kcal/mol for RHOB and −1500 to −2600 kcal/mol for LOSA. Moreover, The drug rejection rate of RHOB for neat is 50 % but increases to 80 % and 90 % with the addition of PE and OCN, respectively, showing their synergistic effect. Similarly, the accumulation rate rises from 6 Å (NH2/UO) to 10 Å (OCN/UO) and 11 Å (PE/UO). For LOSA, the drug rejection rate improves from 30 % to 60 %, while the accumulation rate increases from 4 Å to 8 Å with PE and OCN functionalization. The results demonstrated that functionalizing UO with the chosen biodegradable polymers enhanced its adsorption capacity for both pollutants compared to the pristine form. Notably, the developed adsorbent exhibited a higher affinity towards RHOB dye compared to LOSA pharmaceutical.

Harnessing the power of rhizosphere bacteria for pollution remediation: strategies, mechanisms, and environmental impact: A review

This review explores into the sizeable potential of rhizosphere bacteria as effective mediators in the pollution remediation. These rhizosphere bacteria are primarily found in the soil surrounding plant roots, and they have an extremely strong ability to remove a wide range of toxins from the environment. This is attuned with the idea of phytoremediation, which is the use of plants to clean adulterated soil or water. In addition to vigorous participation in bioremediation processes, their diverse activities include stimulating plant growth and serving as biocontrol agents against plant diseases. Their ability to gather, change, and restrain pollutants is one of their main advantages, especially when used in combination with phytoremediation techniques. To fully utilize these microorganisms, it is essential to understand the various bacterial strains and their complex biological pathways that influence their behavior. The diversity and richness of rhizosphere bacterial populations, significantly affected by different plant species and environmental factors, is a crucial area that requires further study. Grasping this heterogeneity is essential for adapting phytoremediation strategies to particular contamination situations and exploiting their effectiveness. Rhizosphere microorganisms present a feasible path towards a more supportable and clean future. This might potentially make a big contribution to environmental restoration efforts in a world that is always changing.

Improvement of tetracycline removal using amino acid ionic liquid modified magnetic biochar based on theoretical design

In current research, biochar is widely used to remove antibiotic contamination from the environment. However, original biochar produced through direct pyrolysis has significant limitations in removing antibiotics. In this paper, response surface methodology provided the laudable choice for magnetic poplar biochar (MPBC) considering the synergistic effect of multi-factors as well as the restrictions abundance experiments during the preparation of MPBC. Amino acid ionic liquids (AAILs) are a class of ionic liquids in which amino acids act as the anionic component, combining the tunable properties of ionic liquids with the biocompatibility and functionality of amino acids. To ameliorate adsorption capacity of MPBC, tetra-ethylammonium glycinate ([TEA][Gly]) with the best affinity for tetracycline (TC) were screened from 600 AAILs based on theoretical predictions using the conductor-like screening model for real solvents (COSMO-RS) without extensive experimental. Furthermore, AAILs-modified magnetic biochar (MPBC-AAIL) was synthesized chemically for the first time. Adsorption kinetics, isotherms, and thermodynamic analyses revealed that TC adsorption by both MPBC and MPBC-AAIL is a monolayer, spontaneous, and exothermic chemical process. Moreover, MPBC-AAIL exhibited a maximum adsorption capacity of 305.9 mg·g−1. Meanwhile, MPBC-AAIL maintains superior adsorption performance for TC in different impurity solutions as well as in real water samples. The excellent reusability and selective adsorption capacity of the material demonstrate the superiority of the theoretical based design. The characterization reveals that the adsorption mechanisms include pore filling, π-π interactions, surface complexation, hydrogen bonding, and electrostatic interactions. In addition, theoretical calculations showed that ionic liquid modification altered the adsorption sites between TC and MPBC-AAIL, leading to enhanced adsorption. This comprehensive study introduces an innovative modification of biochar, providing a novel approach to designing biochar composites and promoting their application in the remediation of complex environmental pollution.

Optimization of a Groundwater Pollution Monitoring Well Network Using a Backpropagation Neural Network-Based Model

Selecting representative groundwater monitoring wells in polluted areas is crucial to comprehensively assess groundwater pollution, thereby ensuring effective groundwater remediation. However, numerous factors can affect the effectiveness of groundwater monitoring well network optimizations. A local sensitivity analysis method was used in this study to analyze the hydrogeological parameters of a simulation groundwater solute transport model. The results showed a strong effect of longitudinal dispersion and transverse dispersion on the output results of the simulation model, and a good fit between the backpropagation neural network (BPNN)-based alternative model’s results and those obtained using the solute transport simulation model, accurately reflecting the input and output relationship of the simulation model. The optimized groundwater monitoring layout scheme consisted of four groundwater monitoring wells, namely no. 7, no. 16, no. 23, and no. 24. These wells resulted in a groundwater fluoride pollution rate of 98.44%, which was substantially higher than that obtained using the random layout scheme. In addition, statistical analysis of the fluoride groundwater pollution results obtained using the Monte Carlo random simulation highlighted continuous and high groundwater fluoride levels in the second and third pollution sources and their downstream groundwater. Therefore, more attention should be devoted to these sources to ensure the effective remediation of groundwater pollution in the study area.

Remediation of Cd-As-Ni co-contaminated soil by extracellular polymeric substances from Bacillus subtilis: Dynamic improvements of soil properties and ecotoxicity

As the primary reservoir of heavy metals in nature, soil is highly susceptible to significant co-contamination with Cd-As-Ni. In current study, extracellular polymeric substances (EPS) from Bacillus subtilis were utilized as a novel improver to simultaneously enhance soil property and restrain ecotoxicity in Cd-As-Ni co-contaminated soil. Our findings revealed that EPS effectively bound and immobilized free Cd, As, and Ni in soil and decreased the 49.73 % of soil available Cd, 79.16 % of As and 77.87 % of Ni contents by increasing soil pH, soil organic matter and cation exchange capacity. The EPS was also found to inhibit the Cd-As-Ni induced ecotoxicity in Caenorhabditis elegans by increasing the activities of antioxidant enzymes including superoxide dismutase, glutathione, and catalase. The remediation of EPS showed progressive improvement over time, and maintained a lasting effect after achieving peak efficiency. Our results might provide a new perspective on the potential of EPS in remediation of soil heavy metal pollution and the development and utilization of microbial biomass resources in a wider range.

Z-Scheme Ag2S-Ag-In2O3 Heterostructure with Efficient Antibiotics Removal under Natural Sunlight.

The widespread distribution of antibiotics in natural waters is a great threat to human health. Photocatalytic degradation is an environmentally friendly technology to remediate antibiotic-polluted waters, driven by endless solar energy. Herein, a Z-scheme Ag2S-Ag-In2O3 heterostructure photocatalyst is prepared to remove antibiotics under environmental conditions. Under natural sunlight (light intensity: ∼78 mW/cm2) irradiation, the optimal Ag2S-Ag-In2O3 (10-ASAIO) exhibits considerable performance for decomposing diverse antibiotics, including norfloxacin (NOR), tetracycline hydrochloride, sulfisoxazole, ciprofloxacin, chlortetracycline hydrochloride, and ofloxacin. The NOR photodegradation rate constant of 10-ASAIO reaches 0.025 min-1, which is 12.50, 5.00, and 6.25 times higher than that of In2O3 (0.002 min-1), Ag-In2O3 (0.005 min-1), and Ag2S-In2O3 (0.004 min-1), respectively. This performance of the 10-ASAIO photocatalyst for decomposing NOR under natural sunlight exceeds most of the previously reported photocatalysts under a xenon lamp. Particularly, due to the intermittency of natural sunlight, a light-emitting diode (LED) lamp (light intensity: 5.1 mW/cm2) is also used as a light source, and 72.20% of NOR can be degraded with irradiation for 12 h. The effects of many water characteristics (water bodies, coexisting inorganic anions, pH, and humic acid) on the degradation performance of 10-ASAIO have been investigated, which exhibits stable degradation efficiency in variable aquatic environments. A 10-ASAIO catalyst-coated frosted glass sheet is fabricated to settle the problem of recovery of powder photocatalysts, and the immobilized catalyst shows outstanding activity and stability to decompose NOR. The photocatalytic mechanism and pathway of degrading NOR over 10-ASAIO have also been systemically investigated and proposed. The ecotoxicity (phytotoxicity and biotoxicity) of the 10-ASAIO photocatalyst and treated NOR solution have been tested by their toxic effects on cabbage seeds and Staphylococcus aureus (S. aureus). This work provides a feasible photocatalytic system for environmental pollutant remediation under natural sunlight or an LED lamp.

Efficient Toluene Decontamination and Resource Utilization through Ni/Al2O3 Catalytic Cracking.

Volatile organic compounds (VOCs), particularly aromatic hydrocarbons, pose significant environmental risks due to their toxicity and role in the formation of secondary pollutants. This study explores the potential of catalytic pyrolysis as an innovative strategy for the effective remediation and conversion of aromatic hydrocarbon pollutants. The research investigates the high-efficiency removal and resource recovery of the VOC toluene using a Ni/Al2O3 catalyst. The Ni/Al2O3 catalyst was synthesized using the impregnation method and thoroughly characterized. Various analytical techniques, including scanning electron microscopy, X-ray diffraction, and N2 adsorption-desorption isotherms, were employed to characterize the Al2O3 support, NiO/Al2O3 precursor, Ni/Al2O3 catalyst, and the resulting solid carbon. Results indicate that Ni predominantly occupies the pores of γ-Al2O3, forming nano/microparticles and creating interstitial pores through aggregation. The catalyst demonstrated high activity in the thermochemical decomposition of toluene into solid carbon materials and COx-Free hydrogen, effectively addressing toluene pollution while recovering valuable resources. Optimal conditions were identified, revealing that a moderate temperature of 700 °C is most favorable for the catalytic process. Under optimized conditions, the Ni/Al2O3 catalyst removed 1328 mg/g of toluene, generated 915 mg/g of carbon material, and produced 1234 mL/g of hydrogen. The prepared carbon material, characterized by its mesoporous structure and high specific surface area graphite nanofibers, holds potential application value in adsorption, catalysis, and energy storage. This study offers a promising approach for the purification and resource recovery of aromatic volatile organic compounds, contributing to the goals of a circular economy and green chemistry.