Search Results (1,977)

Ammoniacal nitrogen (NH₃-N) is a major pollutant in municipal, industrial, and agricultural wastewaters and is a key driver of eutrophication and aquatic ecosystem degradation. This review paper assessed the potential of water hyacinth (Eichhornia crassipes) as a sustainable phytoremediation option for removing ammoniacal nitrogen from wastewater. This paper focused on the plant’s biological characteristics, nutrient uptake pathways, and adaptability to varying environmental conditions. Specific mechanisms examined include direct root uptake of ammonium, internal translocation, and microbial-assisted nitrification and denitrification within the rhizosphere. The influence of pH, temperature, salinity, retention time, and plant density on removal efficiency was also assessed in this study. Across laboratory, pilot, and field-scale studies, water hyacinth achieved ammoniacal nitrogen removal efficiencies ranging from 74% to 97% under favorable conditions, alongside significant reductions in biochemical oxygen demand (BOD), chemical oxygen demand (COD), and total dissolved solids (TDS). Integration with constructed wetlands, microbial systems, and hybrid treatment approaches further enhanced nitrogen removal and process stability. This paper also highlighted opportunities for biomass valorization through biogas, bioethanol, and compost production while identifying challenges related to salinity sensitivity and biomass management. Overall, water hyacinth emerges as a cost-effective, nature-based solution for decentralized wastewater treatment, with strong potential to support sustainable water management and circular bioeconomy initiatives. Full article

The release process of endogenous phosphorus (P) in the sediments of large ecological wetlands and their connected rivers in the plain river network area shows temporal and spatial differences. This study investigated P dynamics of the sediments in a large ecological wetland and its connected rivers in a plain river network area. Sample collection occurred across three periods (October 2024, March 2025, and July 2025). P source-sink characteristics and microbial regulatory mechanisms were analyzed to clarify differences in the P release processes between wetland (SS) and river (SH) sediments. The results showed that the total phosphorus (TP) concentration in overlying water was highest in July (0.16 mg/L), while the TP content in SS was relatively low, with a mean value of 514.1 mg/kg. SS generally acted as a P sink, with its zero equilibrium P concentrations (EPC₀) significantly lower than those of river sediments (SH), reaching a minimum of 0.01 mg/L, and its maximum P sorption capacity (Q_max) higher, with a maximum value of 1.413 mg/g. In contrast, SH mainly served as a P source, with a particularly high release risk in spring and summer. Seasonal changes significantly influenced P behavior, and sorption capacity was highest in spring (March), while the high EPC₀ of SH still facilitated P release under actual water conditions. In autumn, elevated microbial diversity enhanced organic matter mineralization to increase EPC₀ and P release risk (p < 0.05), while in summer, specific functional phyla (Proteobacteria and Bacteroidota) simultaneously regulated both adsorption capacity (Q_max) and release threshold (EPC₀) through organic matter mineralization, iron reduction, and competitive sorption (p < 0.05). This study provides scientific support for internal pollution control in ecological wetlands and watershed phosphorus management in plain river network areas. Full article

Chromium (Cr) is a common heavy-metal pollutant that poses a significant threat to both the environment and human health. Herein, a novel strain Lysinibacillus capsici FPHNCRA4-48, with a high Cr tolerance and removal performance, was isolated from Cr-contaminated plant water in Changde, Hunan Province. Structural characterization and proteomic analyses were performed to investigate the Cr removal performance and molecular mechanism of L. capsici FPHNCRA4-48. FPHNCRA4-48 can effectively remove more than 99% of the Cr(VI) at an initial concentration of 1000 μmol/L. The FTIR, 3D-EEM, and XPS results revealed that -OH, -NH₂, and -CO-NH₂ derived from extracellular polymeric substances (EPSs) were mainly involved in Cr(VI) removal. Interestingly, the protein content in the EPS increased significantly (1.32-fold) after exposure to Cr(VI). Moreover, proteomic analysis revealed that genes (rpmA, rpmI, rpmC, rplI, rpmD, deoB, deoC) related to translation and carbohydrate metabolism, and genes (pyk, icd, rpiB, eno) related to amino acid biosynthesis were all significantly up-regulated, suggesting that these pathways related to protein synthesis in L. capsici FPHNCRA4-48 were activated under Cr(VI) stress. Finally, KEGG ribosome pathway enrichment occurred. These data highlight the importance of microbial EPSs in bioremediation in Cr-polluted environments. This study identified highly efficient Cr(VI)-removing bacterial strains and conducted an in-depth analysis of the removal mechanism of their extracellular polymeric substances (EPSs), thereby providing theoretical foundations and technical support for the biological remediation of Cr(VI)-contaminated water bodies. Full article

Rivers are dynamic systems that flow from higher elevations to lowlands, eventually discharging into lakes, seas, or oceans, and play a key role in sustaining ecosystems and supporting human activities. River basin characterisation extends beyond the watercourse itself, encompassing land uses, tributaries and hydromorphological features that influence ecological processes. This review analyses three river basins in northern Portugal, Ave, Douro, and Vouga, using a holistic characterisation approach. These basins represent contrasting river systems in terms of size, hydrological regulation and dominant land uses, while simultaneously being subject to pressures frequently reported in many other river basins in Europe, and around the world. The analysis includes a general basin description, a hydromorphological assessment with emphasis on land use, and an evaluation of water ecological status, with particular focus on estuarine ecosystems. Water quality in the three basins has been strongly influenced by anthropogenic pressures, including industrial and agricultural activities, and wastewater discharges. Although the implementation of the European Water Framework Directive has led to improvements in recent decades, the degree of recovery varies among basins. Persistent challenges, such as nutrient concentrations, microbial contamination, and heavy metal pollution, highlight the need for integrated river basin management and improved monitoring strategies. This review provides transferable insights for the management of river basins facing similar environmental pressures. Full article

With the rapid development of intensive animal husbandry, the widespread use of livestock and poultry manure as organic fertilizers has become a major anthropogenic source of antibiotic contamination in agricultural soils. Antibiotics, classified as “emerging contaminants” owing to their persistence, biological activity, and potential ecotoxicity, undergo environmental fate processes such as adsorption–desorption, migration, transformation, and degradation upon entering orchard soils, with their behaviors regulated by multiple factors, including soil physicochemical properties, microbial communities, and climatic conditions. Antibiotics not only alter the structure and diversity of soil microbial communities, inhibit soil enzyme activities, and interfere with the cycling of carbon, nitrogen, and phosphorus nutrients but also induce the generation and dissemination of antibiotic resistance genes (ARGs) and affect the growth and reproduction of soil animals, triggering cascading effects on ecological processes. Moreover, antibiotics can be absorbed by fruit tree roots and transported to aboveground organs via the xylem or phloem. By interfering with photosynthesis, disrupting antioxidant systems, and affecting hormone balance, they inhibit the growth and development of fruit trees, thereby altering the appearance, nutritional, and flavor qualities of fruits. Furthermore, antibiotic residues and ARGs in fruits pose potential risks to food safety. This paper thoroughly analyzes the pollution levels, environmental interactions, and disposition of antibiotics in orchard soils, focusing on the mechanisms that influence their impact on soil microecology and biochemical processes. It also explores the absorption, transport, and accumulation patterns of antibiotics in fruit trees, as well as their effects on tree physiology, growth, fruit quality, and safety. Finally, the current research gaps and prospects are identified, aiming to provide a theoretical basis for ecological risk assessment, scientific prevention and control of antibiotic contamination in orchard ecosystems, and safeguarding of agricultural product safety. Full article

The ability of Rhodotorula toruloides DSM 4444 to metabolize low-cost carbon sources such as fatty acids was comprehensively studied. This organism is shown, for the first time, to simultaneously accumulate microbial oils (biofuel precursors) and carotenoids from acetic acid obtained from CO₂ fermentation. This fatty acid is typically the single end product of acetogenic bioconversion of one-carbon gas pollutants (e.g., CO₂ and CO). In the first set of experiments, different aerobic fermentations were carried out in automated bioreactors, with acetic acid in one case and with glucose, a more conventional carbon source, as a control, in another bioreactor. R. toruloides consumed around 80 g/L substrate under both conditions. Maximum lipid content (27.2% g/g dry weight) was reached from 38 g/L glucose, while carotenoid content was higher with acetic acid (1.4 mg/g cell after 54.1 g/L acetic acid consumed), representing a 40% increase compared to glucose (1.0 mg/g cell after 64.2 g/L glucose consumed). Additionally, in the second set of assays, a fermented broth produced by Acetobacterium woodii from CO₂ fermentation, containing residual nutrients and metabolites, was tested. Despite its complex composition, R. toruloides grew and produced carotenoids (up to 0.141 mg/g), showing potential adaptability. To the best of our knowledge, this is the first report on a greenhouse gas-based biotechnological process as a promising sustainable alternative for the valorization of pollutants, e.g., gas emissions, their bioconversion to VFAs, such as acetic acid, and subsequent fermentation of the carboxylic acid into microbial oils, as a source of renewable energy, as well as carotenoids as a high-value nutraceutical product. Full article

Small-scale biogas plants in developing countries present a viable alternative to traditional polluting energy sources, particularly in rural and underserved communities. These systems typically rely on locally sourced livestock manure; however, inconsistent supply often results in underfeeding, reduced biogas production, and, in many cases, system abandonment. Co-digestion with crop residues presents a promising strategy to enhance feedstock availability and system resilience. However, the recalcitrant nature of lignocellulosic biomass and limited access to suitable pretreatment technologies have constrained its adoption. This paper evaluates feasible pretreatment methods for integrating crop residues, especially straw, into small-scale biogas systems. Using the Analytic Hierarchy Process (AHP), pretreatment methods are assessed based on five criteria: (i) technology simplicity, (ii) energy requirements, (iii) capital and operational costs, (iv) effectiveness, and (v) environmental impact. The analysis identifies microbial pretreatment using the liquid fraction of digestate, combined with mechanical size reduction, as the most suitable approach for small-scale implementation, utilizing low-cost, simplified mechanical devices adaptable to various crop residues with minimal energy input. A conceptual design of a demonstration plant is proposed to validate this integrated pretreatment approach and assess its impact on biogas yield, system performance, and technology adoption. The design incorporates an on-site digestate separation unit to supply microbial inoculum and emphasizes simplicity and cost-effectiveness in material handling and energy use. Pilot trials are proposed to evaluate key performance indicators, including specific methane yield (LCH₄/gVS added), volatile solids reduction (%), and methane content increase (%), ensuring evidence-based adoption and practical applicability of the design. Full article

Surface-enhanced Raman scattering (SERS) technology, with its high sensitivity and fingerprinting capability, has shown broad application prospects in environmental monitoring, food safety, biomedicine, and other fields. Electrospinning technology can produce flexible nanofiber membranes with high specific surface area and three-dimensional porous structures, providing an ideal platform for constructing high-performance SERS substrates for multiphasic analysis. This review systematically summarizes the fabrication strategies of fiber-based SERS substrates by using electrospinning technology, classified from three perspectives: material composition (polymer-based, ceramic-based, carbon fiber-based, and metal-based), spatial configuration (inner, surface, and inner-surface), and temporal sequence of plasmonic nanostructure (pre-synthesis, pre-reduction, post-reduction, post-modification, etc.). Furthermore, the sampling methods and measurement approaches of such substrates in liquid-phase, solid-phase, and gas-phase detection are discussed, with a focus on their applications in environmental pollution monitoring, food safety inspection, microbial identification, and biomedical diagnostics. Finally, the comparison of different preparation strategies and potential future directions are discussed, which could offer helpful guidance for the design and application of high-performance flexible SERS substrates. Full article

Plastics are highly persistent materials, and their environmental degradation can potentially exacerbate, rather than alleviate, pollution. The degradation of plastic materials releases toxic monomers and additives, such as bisphenol A (BPA), styrene, and dioxins, which are more reactive, harmful, and persistent than intact plastics. With half-lives ranging from weeks to decades, they bioaccumulate in food chains, disrupt ecosystems, and contribute to endocrine disruption and mutagenicity. Natural degradation pathways, like microbial metabolism and photodegradation, are slow and incomplete, often leaving toxic intermediates such as microplastics. Artificial strategies, including bioremediation and advanced oxidation processes (AOPs), show potential to address the problems of plastic pollution but face additional challenges like secondary pollution and scalability. Sustainable alternatives, including bioplastics and renewable non-plastic substitutes, present promising solutions. However, their widespread adoption is hindered by challenges such as high production costs and the need for specific conditions to facilitate degradation, necessitating further research and development. A combined approach of reducing plastic production, advancing recycling, and implementing effective remediation strategies is critical to mitigating plastic pollution’s long-term impacts on ecosystems, biodiversity, and human health. This review provides a critical analysis of the current understanding of plastic degradation processes and the toxic byproducts they generate. It highlights the paradox wherein increased degradability may exacerbate environmental hazards. Additionally, the review assesses innovative, eco-friendly alternatives designed to mitigate plastic pollution. Full article

Constructed wetlands (CW) are a low-cost alternative for wastewater treatment, where microbial communities play a key role in the biotransformation of pollutants, including sulfur compounds. This study reports the identification of cultivable bacteria involved in the sulfur cycle (SC) in a subsurface-flow CW located in Tetipac, Mexico. Water, sediment, and rhizosphere samples were collected during four sampling events and plated on a mineral medium with thiosulfate. Colony-forming units were quantified, and 15 isolates were genetically identified by partial 16S rRNA gene sequencing. Bacterial abundance was higher in the rhizosphere, and the cultivable fraction was dominated by Pseudomonadota, particularly Gammaproteobacteria, accompanied by Bacteroidota and several previously uncultured lineages; genera such as Achromobacter, Chitinophaga, Enterobacter, Pseudomonas, Raoultella and Stenotrophomonas were recovered. Biochemical assays revealed heterogeneous metabolic profiles, with several isolates showing activities comparable to canonical sulfur-oxidizing bacteria (SOB). Most isolates oxidized thiosulfate and a substantial proportion oxidized elemental sulfur, with higher metabolic performance in rhizosphere isolates and a positive association with BOD₅ removal. Overall, these results indicate that the Tetipac wetland harbors a cultivable community of largely non-canonical SOB whose mixotrophic versatility and spatial differentiation suggest a key contribution to the SC and organic matter degradation in CW. Full article

Accelerated industrialization has caused complex mixed toxicant pollution, where synergistic or antagonistic interactions render conventional detection methods inadequate. Herein, we develop an integrated framework by pioneering the integration of microbial electrochemical systems (MECs) with machine learning (ML) for quantifying formaldehyde, tetracycline, Ag⁺, and Cu²⁺ in multi-component, multi-ratio, and multi-concentration mixtures. MECs generated dynamic current–time (I–t) signals responsive to toxicant stress, though signal overlap from mixed toxicants hindered direct quantification. Guided by toxicokinetics and electrochemical mechanisms, we developed a novel mechanism-driven feature engineering strategy with exclusively original indicators, which extracted 22 multidimensional features capturing instantaneous characteristics, kinetic patterns, and microbial stress-adaptive responses to resolve signal ambiguity, and provided biologically meaningful, high-information feature inputs that effectively bridge electrochemical response signals and ML modeling. Comparative analysis of four ML models (SVM, KNN, PLS, and RF) showed RF outperformed others, achieving R² > 0.9 for all toxicants (formaldehyde: 0.959; tetracycline: 0.934; Ag⁺: 0.936; Cu²⁺: 0.957) with minimized MAE and RMSE. Microbial community analysis identified Geobacter anodireducens (71.5%, electroactive for heavy metals) and Comamonas testosteroni (12.9%, organic degrader) as key functional taxa, supported by KEGG enzyme abundance data. This work overcomes traditional MEC limitations via innovative feature engineering and pioneering ML integration, providing a rapid, low-cost, and high-accuracy tool for environmental mixed toxicant monitoring. Full article

Urbanisation is a major driver of ecological change, altering the composition and functioning of ecosystems through land use conversion, pollution, and environmental fragmentation. Although some authors reported that air pollutants could be absorbed and detoxified by the endophytic microbiome of urban trees, the specific mechanisms by which urban air pollution shapes the endophytic microbiome and, consequently, the trees’ capacity for pollutant degradation, remain largely unexplored. The aim of the present study was to: (1) analyse the structure of endophytic bacteriome of the phyllosphere of three widely planted ornamental tree species—Tilia tomentosa, Fraxinus excelsior, and Pinus nigra, growing at four locations within the city of Plovdiv, Bulgaria, with different anthropogenic load; and (2) assess the effects of host species and urban environmental exposure on bacteriome diversity, taxonomic composition, and functional capacity. Functional profiling based on 16S rRNA gene sequencing revealed enrichment of the metabolic pathways associated with nitrogen cycling, carbon metabolism, and hydrocarbon degradation, particularly in samples originating from more urbanised or polluted locations. These predicted functional traits suggest that endophytic bacteria may actively contribute to detoxification processes within plant tissues. Tilia tomentosa and Fraxinus excelsior were enriched in nitrogen and carbon cycling pathways, including denitrification, methanol oxidation, and methanotrophy—functions associated with oxidative stress mitigation and nutrient regulation. In contrast, Pinus nigra showed higher relative abundance of chemoheterotrophy, ureolysis, and sulphur respiration, indicating a more conservative and stress-tolerant microbiome. Although the study involved only one settlement, these results suggest that endophytic communities may contribute to urban tree sustainability by supporting ecosystem functions under stress conditions. By integrating microbial ecology with urban environmental assessment, this research provides new insights into the adaptive potential of endophytic microbiota in urban forests and highlights their importance in the sustainable management of green infrastructure through microbiome-informed strategies. Full article

Microbial communities are key regulators of ecological processes in aquatic ecosystems and serve as sensitive indicators of environmental change. Here, we investigated the diversity, assembly mechanisms, and spatial differentiation of bacterial and fungal communities across three representative regions of Dianchi Lake—a large, shallow, eutrophic plateau lake in Southwest China characterized by severe nutrient enrichment and organic pollution. The lake was divided into a submerged macrophyte remnant zone (SubmP), the heavily polluted Caohai area (hPollut), and a cyanobacterial bloom zone (HABs). Amplicon sequencing of the 16S rRNA and ITS genes revealed 7862 bacterial and 3141 fungal OTUs, spanning 69 bacterial phyla (1128 genera) and 9 fungal phyla (477 genera). Although 69 dominant bacterial genera (e.g., Flavobacterium) and 9 dominant fungal genera (e.g., Metschnikowia) were shared across regions, pronounced spatial heterogeneity was observed, primarily driven by total nitrogen and dissolved oxygen. Taxonomic richness and abundance were decoupled: rare (RT) and intermediate taxa (IT) accounted for the most richness, whereas abundant taxa (AT) dominated the total abundance but exhibited comparatively low diversity. IT and RT displayed significantly higher Shannon diversity and greater network robustness than AT; bacterial RT showed the highest robustness (0.35–0.45), while fungal IT demonstrated superior resilience. Community assembly was largely governed by stochastic processes (59–99% contribution), yet deterministic selection exerted stronger effects on IT and RT, particularly for bacteria in SubmP, where habitat heterogeneity enhanced environmental filtering. Functional prediction revealed distinct ecological strategies, with enhanced nitrogen cycling in hPollut, phototrophy in HABs, and pollutant degradation in SubmP. Collectively, these findings demonstrate that rare and intermediate taxa, rather than numerically dominant populations, underpin microbial stability and spatial differentiation in eutrophic lakes, highlighting the importance of nitrogen management and habitat heterogeneity in lake restoration. Full article

Membrane bioreactors (MBRs) exhibit highly variable removal efficiencies for pharmaceutical metabolites and organic micropollutants, even under similar operating conditions. Diclofenac and carbamazepine, for instance, show elimination rates that differ markedly across installations and studies. The membrane’s separation parameters—pore size, diameter, or structure—and the chemical nature of its material do not fully explain these differences. Instead, processes at the sludge–membrane interface, particularly sorption and biofilm-related interactions, appear to dominate. Recent studies indicate that MBR performance depends largely on events at the membrane surface: microbial adhesion mechanisms, biofilm development, and community organization. Better pollutant removal stems from prolonged contact with the biofilm and transformation within this layer, not from mechanical filtration alone. Here, we examine membrane surface modification strategies using biopolymers (cellulose, chitosan, and alginate) and their effects on membrane–biofilm interactions. Research suggests that effective biopolymer coatings for MBRs must stabilize the hydration layer, maintain near-neutral surface charge, show moderate cross-linking density for durability and flexibility, and create controlled nanotopography that favors porous, active biofilms over compact sludge layers. This understanding supports the development of durable, low-energy MBR membranes with improved stability and more predictable micropollutant removal in real-world applications. Full article

Microplastic pollution is increasingly serious worldwide, threatening human and animal health. The cow rumen is a key organ for nutrient digestion and absorption, and its fermentation is closely related to rumen microorganisms. Here, we investigated how polystyrene microplastics (PS-MPs) with varying particle sizes and concentrations affect rumen fermentation and the biodegradability of PS-MPs by rumen fermentation. The results reveal that exposure to PS-MPs lowered gas production and gas concentrations, as well as volatile fatty acid content, and these decreases were positively correlated with PS-MP concentration. However, higher PS-MP concentration and larger particle size increased the activity of carboxymethyl cellulose, β-glucosidase, and xylanase. Furthermore, PS-MP exposure reduced the abundance of certain rumen microorganisms and altered metabolic pathways and metabolites linked to PS-MP biodegradation. It was also found that PS-MP content decreased significantly after 24 h fermentation. Therefore, PS-MPs can inhibit rumen fermentation by affecting the rumen microbiome, and rumen microorganisms and their secreted enzymes can biodegrade PS-MPs to produce styrene and derivatives; such small molecules may further disrupt rumen homeostasis, thereby affecting lactation performance. In addition, rumen microbial degradation of PS-MPs provides a new idea to resolve future microplastic contamination challenges. Full article