Journal of Environmental Science and Health Part A-toxic\/hazardous Substances & Environmental Engineering最新文献

To address growing energy demand and promote environmental sustainability, the development of diverse biomass-based renewable energy is crucial. Co-digestion of Chlorella and sludge has been recognized as an effective strategy to improve methane production efficiency from biomass. This study aimed to explore the optimal ratio of Chlorella and sludge. On this basis, hydrothermal pretreatment was applied to the Chlorella-sludge mixture to investigate the temperature effects on co-digestion performance. This step aimed to optimize methane yield and identify the most suitable pretreatment temperature. The anaerobic digestion kinetics were evaluated by fitting experimental data to both the Fitzhugh first-order kinetic model and the Modified Gompertz model. Additionally, metagenome sequencing was performed on samples before and after hydrothermal pretreatment to elucidate the impact of pretreatment on microbial community dynamics during the acidogenesis phase of anaerobic digestion. The experimental results demonstrated that a 20-day co-digestion period with a VS Chlorella to VS sludge ratio of 2:1 yielded the highest biogas production, reaching 250.98 mL/g VS. After 30 min of hydrothermal pretreatment at 180 °C, the co-digestion efficiency of Chlorella and sludge reached the optimal level, with a cumulative methane production of 261.02 mL/g VS, which had a significant impact on microbial diversity.

Polyethylene nanoplastics (PE-NPs) are emerging wastewater contaminants that may disrupt biological phosphorus removal (BPR). To assess their effects on BPR, experiments with PE-NPs at 0-20 mg/L were conducted. With increasing PE-NPs, phosphorus removal declined from 96.16% to 83.97% and effluent COD increased from approximately 20-43.04 mg/L. At 20 mg/L PE-NPs, anaerobic PHA synthesis and aerobic PHA consumption were measured at 83.19% and 82.74% of the control values, respectively. Total EPS dropped from 136.78 to 118.26 mg/g MLVSS alongside a minor increase in the PN/PS ratio, and intracellular ROS levels reached about 128% of those in the control. Fluorescence excitation-emission matrix and Fourier-transform infrared spectroscopy analyses indicated a reduction in aromatic protein and microbial by-product signals, alterations in N-H/O-H and amide-I hydrogen bonding environments, and a shift in EPS protein conformation from α-helix to β-sheet/aggregate-rich structures. High-throughput sequencing revealed a microbial community shift, marked by a decrease in phosphorus-accumulating organisms (PAOs, e.g., Acinetobacter and Candidatus Accumulibacter) and an increase in glycogen-accumulating organisms (GAOs, notably Candidatus Competibacter). This shift intensified carbon competition, limiting PAOs energy storage and phosphate uptake. These combined effects-oxidative stress, altered EPS, and microbial shift-decouple carbon-phosphorus metabolism, accelerating BPR deterioration.

Microplastic (MP) pollution poses a growing threat to coastal ecosystems worldwide. This study evaluates the abundance, spatial distribution, shapes, and polymer composition of MPs in two Mediterranean lagoons: El-Mellah (Algeria) and Bizerte (Tunisia). Quantitative analysis revealed high MP concentrations in both lagoons, with mean values of ∼75.7 particles kg^-1 in El-Mellah and ∼73.4 particles kg^-1 in Bizerte. El-Mellah exhibited a more homogeneous spatial distribution, whereas Bizerte showed marked site-to-site variability. Fragments were the dominant shape category in both systems (up to 55% in Bizerte and 51% in El-Mellah), while fibers were relatively more abundant in El-Mellah (up to 38%). Polyethylene was the most prevalent polymer (33-44%), followed by polyethylene terephthalate (22-31%) and polypropylene (17-22%), reflecting common plastic usage patterns and discharge sources. These findings highlight distinct pollution dynamics linked to local anthropogenic activities and hydrodynamic conditions. The study underscores the urgent need for targeted management and monitoring strategies to mitigate MP contamination and protect these ecologically important lagoon environments.

Due to the difficult degradation of organochlorine pesticides (OCPs), it has long existed in soil environmental media and has serious adverse effects on farmland and agricultural products. This study took Faku County as the soil sampling area to detect the residual concentration of organochlorine pesticides, and analyze the composition and spatial distribution characteristics. The total residual concentration of organochlorine pesticides in soil of Faku County ranged from 0 to 216.40 μg/kg, and the areas with higher residual concentration were mainly distributed in the northeast and south. Hexachlorobenzene (HCB), p,p'-DDE, endrin ketone (EK), p,p'-DDD, o,p'-DDT and p,p'-DDT were mainly detected. The residual concentration of p,p'-DDT was the highest, and the contribution rate was as high as 61.7%. The average residual concentration levels of grain soil (17.26 μg/kg) and vegetable soil (28.74 μg/kg) in Faku County were quite different, but the similarity of organochlorine pesticide residues was high. The results of carcinogenic risk assessment showed that the carcinogenic risk of Faku County to adults and children was still at a low level, but the carcinogenic risk of children (8.05 × 10^-8) was higher than that of adults (3.61 × 10^-8). However, in terms of ecological risk assessment, the maximum risk quotient (RQ) value of organochlorine pesticides in Faku County was as high as 3.284, far exceeding the threshold 1, and there was a high ecological risk to invertebrates. Therefore, effective remediation measures should be taken to reduce the residues of organochlorine pesticides in soil and reduce the harm to the ecological environment.

Free living animals are sensitive indicators of the environment pollution by polychlorinated biphenyls (PCBs) and other organic pollutants. The aim of this study was to determine polychlorinated hydrocarbons in the depot fat of red foxes (Vulpes vulpes L.) living in the natural environment of south-western Slovakia. The analyses performed included dichlorodiphenyltrichloroethane (DDT), hexachlorobenzene (HCB) and polychlorinated biphenyls (PCBs). The gas chromatograph equipped with an electron capture detector (ECD) was used. The accumulation of pollutants in depot fat of animals followed the order PCB > DDT > HCB. Of all pollutants, the total concentration of PCBs was significantly higher (p < 0.05) in fat tissue of foxes (1.445 ± 0.174 mg/kg) in comparison to DDT (0.1120 ± 0.24 mg/kg) and HCB 0.052 ± 0.010 mg/kg). Compared to samples from females (0.962 ± 0.110 m/kg), significantly higher (p < 0.05) PCB levels were found in samples from males (1.751 ± 0.293 mg/kg). Moderate positive correlation (r = 0.5509) between PCB and HCB was detected. Wild animals can act as indicators of environmental pollution by polychlorinated hydrocarbons, making their monitoring an ongoing priority.

Polycyclic aromatic hydrocarbons (PAHs) pose a significant environmental challenge due to their toxicity that are harmful to living organisms, and commonly found in various ecosystems. Degradation using natural indigenous bacteria is the most cost-effective solution to remove PAHs in the environment. This study examines Sdt-1, an isolated bacterial consortium from agricultural soil in Wakabayashi-ward, Sendai, Japan, capable of degrading PAHs. Sdt-1 was incubated to a solution containing fluorene, phenanthrene, and pyrene in Bushnell Hass Medium (BHM) with 100 mg/L concentration of each compound. Fluorene degraded at the fastest rate, then phenanthrene, while pyrene was the slowest due to its higher molecular weight. Cloning of the 16S rRNA gene showed that Sdt-1 consists primarily of 48% Castellaniella, 16% Mycobacterium, 14% Desulfonatronum, 10% Azospirillum, and 2% each of several other genera. The dynamics of the Sdt-1 was tracked over the 15-d incubation periods through the PCR-DGGE analysis, showing Mycobacterium as the dominant PAH degrader. Correlation between bacterial activity and PAH-degrading genes (nidA and gram-positive PAH-RDH) demonstrates that specific microbes are in charge of various degradation phases. This study enhanced our understanding of the mechanics, characteristics, and the potential role for bioremediation applications of aerobic PAH-degrading bacteria from paddy soil in agricultural land.

The ketamine (KET) and its analogs consumed by humans are becoming emerging contaminants (ECs), as they at present in surface waters after being carried through wastewater systems. Drugs in wastewater can be analyzed using the direct-injection method, a simple wastewater analysis (WWA) method that can provide objective, continuous and nearly to real-time findings. This article describes an ultra-high-pressure liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method for the simultaneous quantification and confirmation of seven KET-based ECs in wastewater by direct injection. After optimization of the UPLC-MS/MS and sample pretreatment conditions, the method was validated and applied to samples (n = 157) collected from several wastewater treatment plants (WWTPs) in southern China in which KET had the highest detection rate. The established direct-injection method was not only simple to perform but also had better sensitivity, shorter detection times, and analyzed more KET-based ECs than currently published methods, meeting the requirements for the monitoring and high-throughput analysis of common KET-based ECs. We also analyzed the fragmentation pathway of KET-based ECs to obtain product ion information on other unknown substances. Additional studies are needed to establish a comprehensive direct-injection screening method of ECs in wastewater on model-based assessment.

The distribution of antibiotic resistance genes (ARGs) in Laizhou Bay affects the local socio-economic development. The study aimed to investigate the distribution of ARGs in the rivers that flow into the sea around Laizhou Bay's southern shore. Water and sediment samples were collected from different typical sites of rivers entering the sea in Weifang, including Mi River, Bai Lang River, Yu River, Wei River, Jiaolai River, Xiaoqing River and Di River. The species and abundance of ARGs in the sediments were characterized and quantified by macro-genome high-throughput sequencing technology. The species distribution of ARGs was compared. In two sediment samples and seven water samples, 24 ARGs types and 1244 subtypes of ARGs were detected, in which multidrug-resistant class was the main ARGs type and FBJ murine osteosarcoma viral oncogene homolog B (fosB) was the dominant ARGs. The types of ARG in the top ten of these samples were the same, although the proportion was different. Dominant ARG subtypes accounted for more than 50% of all the nine samples. This article provides basic data support for pollution status and environmental risk assessment as well as remediation of ARGs in rivers entering the sea along the south coast of Laizhou Bay.

Cellulose was isolated from recycled pulp and paper sludge and used to synthesize cellulose nanocrystals. Response surface methodology and Box-Behnken design model were used to predict, improve, and optimize the cellulose isolation process. The optimal conditions were a reaction temperature of 87.5 °C, 180 min with 4% sodium hydroxide. SEM and TEM results revealed that the isolated cellulose had long rod-like structures of different dimensions than CNCs with short rod-like structures. The crystallinity index from XRD significantly increased from 41.33%, 63.7%, and 75.6% for Kimberly mill pulp sludge (KMRPPS), chemically purified cellulose and cellulose nanocrystals, respectively. The TGA/DTG analysis showed that the isolated cellulosic materials possessed higher thermal stability. FTIR analysis suggested that the chemical structures of cellulose and CNCs were modified by chemical treatment. The cellulose surface was highly hydrophilic compared to the CNCs based on the high water holding capacity of 65.31 ± 0.98% and 83.14 ± 1.22%, respectively. The synthesized cellulosic materials portrayed excellent properties for high-end industrial applications like biomedical engineering, advanced materials, nanotechnology, sustainable packaging, personal care products, environmental remediation, additive manufacturing, etc.

Down-flow hanging sponge (DHS) reactors, employed in domestic wastewater treatment, have demonstrated efficacy in eliminating Escherichia coli and other potentially pathogenic bacteria. The aim of this study was to elucidate the mechanism of removal of E. coli by employing a cube-shaped polyurethane sponge carrier within a compact hanging reactor. An E. coli removal experiment was conducted on this prepared sponge. Escherichia. coli level was found to decrease by more than 2 logs after passing through five nutrient-restricted DHS sponges. Conversely, a newly introduced sponge did not exhibit a comparable reduction in E. coli level. Furthermore, under conditions of optimal nutritional status, the reduction in E. coli level was limited to 0.5 logs, underscoring the crucial role of nutrient restriction in achieving effective elimination. Analysis of the sponge-associated bacterial community revealed the presence of a type VI secretion system (T6SS), a competitive mechanism observed in bacteria. This finding suggests that T6SS might play a pivotal role in contributing to the observed decline in E. coli level.