The present study examines the seasonal and size-resolved elemental composition of fine (PM2.5) and coarse (PM2.5-10) particulate matter in a coastal urban-industrial region influenced by multiple sources, including coal mining, coal combustion for heating and power generation, iron-steel with coke production, maritime fuel-oil use, traffic emissions, and natural marine and crustal sources. Seasonal contrasts were marked, with the heating period PM2.5 characterized by elevated concentrations of toxic elements (As, Sb, Cd, Pb, Se, V, Ni, and Cr) associated with combustion and industrial activities, reflecting intensified heating and industrial activities. Conversely, the composition of non-heating period PM2.5-10 was dominated by crustal, marine, and resuspended dust components, with persistent industrial influence. Enrichment factor (EF) analysis using Ti as a reference element indicated substantial anthropogenic enrichment for combustion and metallurgy, while crustal and marine elements remained near natural levels. Principal Component Analysis (PCA) was utilized to identify distinct seasonal and size-dependent source factors, including coal combustion, iron-steel production, fuel-oil and shipping emissions, traffic non-exhaust sources, crustal dust, marine aerosol, and resuspended coal fly ash. Discriminant Analysis (DA) confirmed clear separation between seasons and particle-size fractions, supporting the internal consistency of the EF-PCA-DA approach without serving as independent validation of source assignments.
Congo red (CR) is a widely used azo dye in the textile industry and is known for its carcinogenic properties. The discharge of CR-containing textile effluents necessitates efficient and sustainable treatment strategies before environmental release. In this study, the ability of the thermophilic bacterium Bacillus smithii AMPNK to biodegrade CR under different physicochemical conditions was evaluated. A maximum CR decolorization of approximately 95% was achieved at 55 °C when maltose was used as the carbon source, while beef extract was the most effective nitrogen source, yielding approximately 87.17% decolorization. The optimum pH for dye degradation was 7.0, with approximately 90% decolorization. UV-Vis, FT-IR, and GC-MS analyses confirmed the occurrence of azo bond cleavage and the formation of lower-molecular-weight degradation metabolites, indicating efficient biodegradation of CR. Laccase activity and total protein analysis further demonstrated that enzymatic degradation was closely associated with the active growth phase of B. smithii AMPNK. Phytotoxicity assays using Vigna radiata and Trigonella foenum-graecum revealed that untreated CR markedly inhibited seedling growth, reducing root length to 2.2 ± 1.23 cm and 2.1 ± 0.81 cm, respectively, whereas treatment with biodegraded metabolites restored root growth to 5.4 ± 1.50 cm and 4.7 ± 1.34 cm, respectively, indicating substantial detoxification. Overall, these findings demonstrate that thermophilic B. smithii AMPNK is a promising biocatalyst for the biodegradation and detoxification of Congo red in high-temperature textile wastewater.
With the extensive application of brominated flame retardants (BFRs) in industry and daily life, their potential impact on human health has gradually drawn attention. This study utilized molecular docking, supplemented by molecular dynamics (MD) simulations, to analyze the interaction mechanism between various BFRs and human serum albumin (HSA). The docking results showed that the binding energy values were generally between -6.32 kcal·mol-1 and -10.98 kcal·mol-1. BFRs mainly anchored to HSA through hydrophobic interactions, hydrogen bonds, and halogen bonds. High-frequency amino acid residues such as PHE104A, LEU70A, and ILE73A repeatedly appeared in multiple docking models, suggesting their core role in the binding process. MD simulations further confirmed the stability of the representative complexes, with protein backbone RMSD values remained 0.20-0.45 nm throughout the 100 ns trajectories, corroborating the reliability of the docking-derived binding poses. Correlation analysis revealed that the physicochemical determinants of binding affinity were subclass-dependent: for PBBs, molecular weight exhibited a significant positive correlation (r = 0.646, p ≤ 0.05), while for PBDEs, density showed the strongest association (r = 0.5045, p ≤ 0.05). These findings indicate that simple bivariate correlations may not fully capture the complex binding mechanisms, and that subclass-specific rather than universal physicochemical predictors should be considered. This study provided a reusable standardized protocol for the research on the interaction between environmental pollutants and biological macromolecules and laid a theoretical foundation for the ecological risk assessment of flame retardants.
Acephate is an organophosphorus pesticide that is widely used to protect a variety of crops worldwide. This study examined the removal of commercial acephate pesticide in the aqueous medium via advanced oxidation process with Silicon carbide (SiC) and Zerovalent Iron (ZVI) under Solar and UV light. The parameters addressed in this study are the pH of the system, the amount of catalyst, and the effect of irradiation time on single and mixed systems. The process exemplified 93.3% and 88.6% removal with UV light and Sunlight, respectively, in the presence of oxidant and ZVI, whereas 85.1% and 82.2% removal were observed with SiC and oxidant along with UV light and Sunlight irradiation after 360 min under optimum conditions. The degradation products produced during the photocatalytic processes were assessed using FTIR analysis. The developed SiC/ZVI-assisted advanced oxidation process shows great promise as an economical and environmentally friendly laboratory technology for the treatment of wastewater, particularly with regard to the remediation of industrial effluents and agricultural runoff containing Acephate pesticide.
Organochlorine pesticides (OCPs) pose persistent threats to aquatic ecosystems and human health due to their bioaccumulative and toxic properties. This study assessed public health risks via oral ingestion of OCP, and revealed historical sources, oxidative degradation, and microbial dechlorination of OCPs. Sixty silver catfish (Chrysichthys nigrodigitatus) samples were collected from upstream (Marina Beach) and downstream (Nsidung Beach) stations, with OCPs analyzed via gas chromatography-electron capture detection. Total OCP concentrations were 3.35 ng g-1 (upstream) and 7.77 ng g-1 (downstream) ww, exceeding FAO/WHO limits for aldrin, endrin, dieldrin, heptachlor, DDT, and endrin ketone. Health risk assessments indicate that consumption of C. nigrodigitatus from the Calabar River poses negligible carcinogenic and non-carcinogenic risks for both adults and children. Positive Matrix Factorization (PMF) resolved four factors: Factor 1 (historical agricultural contamination from heptachlor, DDT, endosulfan I/II, dieldrin, endrin, and methoxychlor); Factor 2 (historical cyclodiene pesticide use); Factor 3 (recent endosulfan and endrin applications); and Factor 4 (historical combined cyclodiene, DDT, and methoxychlor use). These factors revealed combined environmental weathering and in vivo biotransformation processes, including oxidative degradation and dechlorination. Findings underscore the need for OCP monitoring and regulatory enforcement to safeguard public health in tropical river systems.
In this study, polyvinyl chloride (PVC) remediation was carried out using advanced oxidation, which generates sulfate radicals during ultraviolet (UV) irradiation. Because PVC is durable and does not break down on its own, and because it contains harmful chemicals such as vinyl chloride and phthalates, it poses risks to our environment and health. Researchers are focusing on UV-activated persulfate because it generates sulfate and hydroxyl radicals that help break down PVC particles in water. Using UV-visible spectrophotometry, the study tracks PVC degradation. It evaluates the effects of persulfate concentration, pH, temperature, inorganic and transition-metal ions, natural organic matter, and PVC content in the mixture. The findings reveal that the method works best when the water is alkaline and the persulfate dose is appropriate.
This study assessed PM2.5-bound heavy metals (Cd, Pb, Cr, Cu, and Fe) and associated human health risks at a semi-urban-agricultural site in Phitsanulok, lower northern Thailand, during the 2024-2025 haze season. Enrichment factors (EF), geoaccumulation index (Igeo), and US EPA health risk models were applied to characterize metal sources and to estimate noncarcinogenic and carcinogenic risks for adults and children. The mean 24-h PM2.5 concentration (55.96 µg m-3) exceeded both WHO guidelines (15 µg m-3) and the Thai national standard (37.5 µg m-3). Fe was the dominant metal, followed by Cr, Pb, Cu, and Cd; EF > 10 for Cr, Pb, Cu, and Cd indicated significant anthropogenic enrichment, while Igeo classified Cd as moderately polluted. Hazard indices (HI < 1) indicated negligible noncarcinogenic risk for all exposure routes and age groups. However, total inhalation carcinogenic risk exceeded 1 × 10-4 for children (2.13 × 10-4; moderate risk), primarily driven by Cr, while adults presented a lower but non-negligible risk (6.56 × 10-5). These findings identify Cr containing PM2.5 inhalation during haze episodes as a priority health concern, particularly for children, underscoring the need for targeted emission controls in semi-urban-agricultural areas.
Rooftop-rainwater harvesting is increasingly recognized as an alternative water supply that can reduce dependence on centralized water systems. This study evaluated the quality and health risks of rainwater harvested from thatched rooftops, a common roofing type in rural African communities. A total of 75 samples were collected from six rainfall events between October 2020 and December 2021 and analyzed for physicochemical parameters and microbial indicators. Most physicochemical parameters and trace metal concentrations complied with South African National Standards (SANS) and World Health Organization (WHO) drinking-water guidelines. Zinc was the most abundant metal, with concentrations ranging from 26.12 to 154.56 µg L-1. Arsenic exceeded guideline values only in first-flush samples from Tshikudini. Non-carcinogenic health risk assessment indicated negligible risks for most metals, although arsenic slightly exceeded the acceptable hazard quotient threshold for children in Tshikudini. In contrast, microbial contamination was widespread. Escherichia coli concentrations ranged from 13.3 to 104 cfu 100 mL-1, and both E. coli and total coliform counts exceeded recommended limits. Quantitative microbial risk assessment revealed a high probability of infection and illness, reaching 100% in most cases. Although harvested rainwater may be suitable for certain domestic uses, treatment is required before consumption to ensure public health protection.
Biodegradation of biopolymers, which included, PLA (polylactic acid) pellets, PLA film, PBS (polybutylene succinate) pellets, and commercial bioplastics, were studied at various temperatures (40-60 °C), with controlled compost conditions, and incubation periods under aerobic conditions. Most of the biopolymers showed significant cumulative carbon dioxide (CO2) production during the first 20 days, followed by biodegradation log phase and remained in the stationary phase for the remaining days of incubation in compost C1, C2, C3. Initial physio-chemical characteristics, which includes total solids (TS), volatile solids (VS), and carbon content, were moderately high for PLA film as compared to other bioplymers, i.e., 92.5%, 75.4%, 57.3% and 52.34%, respectively. The amount of weight loss of PLA film (>3%) was comparatively higher, followed by PBS, PLA pellets, and bioplastics, respectively. Biodegradation results showed that mineralization was varied with polymer type, compost composition, and temperature. Percentage biodegradation of all biopolymer showed trend as PLA film > PLA pellets > Bioplastic > PBS pellets. Higher degradation was observed under thermophilic conditions (∼69%), and compost C3 consistently exhibited the highest biodegradation efficiency. X-ray diffraction analysis revealed a decrease in the crystallinity index in the degraded biopolymer samples, indicating structural changes and a reduction in crystalline order during biodegradation. Bacterial species in different compost media involved in the biodegradation process was identified as Bacillota sp. Kinetic analysis showed that biodegradation of biopolymers followed Hill model with very high correlation coefficients (R2 ≥ 0.99).
Corn stover and dewatered sewage sludge were co-digested after hydrothermal pretreatment. This study focused on temperature, residence time, and the often overlooked parameter of solids loading. The optimal condition was 180 °C for 1.5 h at 7.5% solids (designated A4), achieving a methane yield of 34.4 mL CH4/g VS, a 71% increase over the untreated control. Kinetic modeling confirmed that hydrothermal pretreatment significantly improved both methane potential and digestion kinetics. Phosphorus transformation analysis revealed that hydrothermal pretreatment promoted the hydrolysis of solid organic phosphorus to orthophosphate in the liquid phase. During anaerobic digestion, microorganisms partially re-assimilate this orthophosphate into organic phosphorus. The net energy balance was positive for all samples, reaching 1.77 kJ/g VS for the A4 condition. Microbial analysis showed that hydrothermal pretreatment selectively enriched hydrolytic and fermentative bacteria (notably Chloroflexi and Synergistetes) and increased the relative abundance of methanogenic Euryarchaeota to 98.6%. This enrichment established a syntrophic network that positively correlated with enhanced methane production. Optimizing solids loading is therefore critical for promoting the dynamic transformation and redistribution of phosphorus species between solid and liquid phases.
The use of advanced treatment processes such as ozonation and activated carbon filtration in full-scale systems is showing promising results worldwide for removing micropollutants (MPs) and reducing ecotoxicological effects from wastewater (WW). In this study, a combined advanced treatment process consisting of ozonation followed by powdered activated carbon (PAC) filtration was evaluated at laboratory-scale and full-scale in a municipal wastewater treatment plant (WWTP) using the same WW collected during a single sampling campaign. A battery of in vitro assays was applied to assess the elimination of toxic effects in both systems. The laboratory-scale treatment operated at a higher ozone dose (0.7 mg O3/mg DOC (dissolved organic carbon)) than the full-scale system (0.1 mg O3/mg DOC) and achieved higher removal efficiencies for baseline toxicity, estrogenic activity, androgenic activity, and dioxin-like activity. Baseline toxicity removal reached 100% in the laboratory-scale treatment compared with 92% at full scale. Estrogenic activity removal was 100% in the laboratory-scale treatment but remained substantially lower at full scale with 62%. The findings indicate that ozone dose is a major explanatory variable influencing treatment performance and emphasize the importance of optimized ozone dosing and post-treatment processes to minimize residual toxicity and transformation products.
This study compared the bacterial community composition of hospital and clinical infections (i.e., biological samples from infected individuals) with that of a hospital wastewater treatment plant (HWTP) (i.e., hospital wastewater samples), focusing on similarities and differences in antimicrobial susceptibility and resistance of these samples. Microbiological analyses, including bacterial identification and antimicrobial susceptibility and resistance testing, were performed according to standardized protocols. An association was observed between hospital-derived isolates and antimicrobial susceptibility, reaching 79.2%, whereas isolates from the HWTP showed a higher association with antimicrobial resistance (41.7%). Resistance rates were pronounced (>30%) across all bacterial groups isolated from the HWTP. Enterobacteriaceae exhibited 34.3% resistance, non-Enterobacteriaceae 52.2%, Streptococcaceae 52.7%, and Micrococcaceae 60.4%. Corresponding susceptibility rates were 50.1%, 36.5%, 26.3%, and 33.3%, respectively. Thus, 15 bacteria strains isolated from hospital/clinic samples and 39 bacteria strains isolated from HWTP samples showed resistance to 3 or more antimicrobials tested. No more than 50% of HWTP isolates were susceptible to the tested antimicrobial agents. In contrast, bacteria isolated from hospital and clinical infections showed overall resistance rates below 10% for each bacterial group. These results highlight the urgent need for more effective hospital wastewater treatment strategies to minimize the emergence and dissemination of antimicrobial resistance.
Phase redistribution of organic contaminants in low-permeability soils strongly influences their persistence, mobility, and remediation, its dependence on coupled environmental conditions remains poorly understood. In this study, chlorobenzene was selected as a representative dense non-aqueous phase liquid contaminant, and its redistribution among vapor, free, dissolved, and adsorbed phases in low-permeability soil was investigated by varying temperature, relative humidity, and dry density. A sequential multi-phase extraction framework was developed to quantify phase-specific fractions, while tree-based machine learning was used to predict redistribution and identify the relative importance of environmental drivers. Molecular dynamics simulations were further conducted to interpret observed trends from the perspective of adsorption-desorption and confined diffusion at the clay scale. Results showed that the vapor phase dominated under most conditions, whereas the free phase remained suppressed. Temperature exerted the strongest control by promoting volatilization and weakening interfacial retention, while relative humidity and dry density jointly regulated aqueous and adsorption domains through changes in water film development and pore structure. This integrated framework provides a quantitative basis for evaluating contaminant persistence and optimizing remediation strategies. In particular, the vapor-phase dominance under thermal driving indicates that vapor extraction and capture should be prioritized during thermally enhanced remediation of chlorobenzene-contaminated low-permeability soils.
Industrial discharges of toxic synthetic dyes, such as anionic Reactive Green 19 (RG-19) and cationic Crystal Violet (CV), threaten aquatic ecosystems. This study investigates the marine brown macroalga Halopteris scoparia as an untreated, mechanically ground biosorbent for removing RG-19 and CV from wastewater. Characterization confirmed a rough surface with a negative charge (-17.8 ± 4.08 mV), favoring cationic dye adsorption. Batch experiments optimized pH and dosage. Optimum removal occurred at pH 5.0 for RG-19 and pH 7.0 for CV. Using a biosorbent dosage of 20.0 g L-1, 95.2% of CV and 31.8% of RG-19 were removed from a 50.0 mg L-1 solution within 120.0 min. The maxımum experımental adsorption capacities were 33.5 and 5.5 mg g-1, respectively. Kinetics followed the pseudo-second-order model, while isotherms fit the Langmuir model for RG-19 and the Freundlich model for CV. Hydroxyl, carbonyl, and polysaccharide groups participated in dye binding. Due to electrostatic attraction, H. scoparia prefers cationic CV over anionic RG-19, proving to be a low-cost, sustainable biosorbent.
Biopolymeric heterostructure semiconductors are continuously being improved for efficient charge separation. Herein, a Tragacanth gum-mediated FeS2/g-C3N4 heterostructure (TFCN) was successfully prepared for solar-driven degradation of organic dyes. The composite was characterized using XRD, FTIR, SEM, UV-Vis Spectroscopy, Zeta Potential and Brunauer-Emmett-Teller (BET) surface analysis. TFCN produced well-defined and evenly distributed grains measuring 0.56 µm. The zeta potential of -54.10 mV disclosed that the TFCN photocatalyst possessed strong electrostatic repulsion and good colloidal stability. TFCN showed superior sunlight-driven photocatalytic degradation of RR 24 (93.57%) compared to FeS2 (FS), g-C3N4 (CN), following pseudo first order kinetics, exhibiting rate constant of 0.03122 min-1 and R2 value of 0.99087. The high degradation efficiency of TFCN is due to synergism between TG, FS, and CN, which enhances the separation of the photogenerated electron/hole pairs. The proposed photocatalytic mechanism confirmed the prominent role of superoxide (O2•-) radicals in the degradation of RR 24 dye. The negative ΔG° (-7.41 J mol-1 K) and the positive ΔH° (41.47 J mol-1) of TFCN indicated its thermodynamically feasible endothermic nature, making it an attractive candidate for water purification.
In this study, g-C3N4 was synthesized from urea, selected using the TOPSIS framework, where urea ranked highest (score = 1). Further catalyst was optimized using the central composite design for the degradation of Tetracycline (TC), a representative Pharmaceutical and Personal Care Product (PPCP). Characterization confirmed a layered structure, surface functionalities, thermal stability, and a visible-light band gap of 2.74 eV. Under optimized conditions (180 min, 0.5 g L-1 catalyst dosage, pH 6.81, 10 mg L-1 TC), degradation efficiencies of 88.23% (Mercury 125 W), 85.93% (Tungsten 500 W), and 78.47% (LED 120 W) were achieved with pseudo-second-order kinetics. Reusability tests showed a ∼13% decline in performance after three cycles. Increasing background organic load (COD) from 0 to 768 mg L-1 prolonged the TC half-life from 87.72 to 144.37 min, indicating competitive inhibition. Scavenger studies identified superoxide radicals (O2•-) and holes (h+) as the dominant reactive species. In real-water matrices, TOC removal decreased due to matrix interference, with removal efficiencies of 68.6% (distilled water), 66.43% (surface water), and 37.17% (Treated Sewage water). LC-MS analysis detected low-molecular-weight by-products (m/z < 200), confirming TC degradation. After AOP treatment, GI values increased from 0.62 to 0.68 for Vigna radiata and 0.39 to 0.8 for Trigonella foenum-graecum, indicating reduced toxicity. PMS-assisted photocatalysis further enhanced TC removal to 94.42% within 2 h. Among the light sources evaluated, LED operation ($0.058 L-1) was the most economical option, supporting scalable PPCPs removal.
