Environmental Quality Management最新文献

Polyphenols are naturally high-valued secondary plant metabolites that demonstrate strong antimicrobial potential besides their well-established health-promoting benefits. The conventional polyphenolic extraction process mostly includes organic solvents, which cause environmental harm. In this context, ionic liquids (ILs) have emerged as an environmentally friendly substitute for traditional solvents to extract various active substances from plants such as coumarins, terpenoids, phenylpropanoids, and flavonoids. This study investigates the synthesis of 1-hexyl-3-methylimidazolium bromide [HMIm][Br], an IL, and studies its impact on the antioxidant and antimicrobial properties of two polyphenolic compounds, gallic acid (GA) and tannic acid (TA), so that it can be effectively used in the extraction process. [HMIm][Br] was synthesized via alkylation and characterized through UV-Vis, FTIR, and NMR techniques. The mixture of [HMIm][Br] with GA and TA demonstrated enhanced antioxidant activity in DPPH assays; 77% and 82%, respectively, in comparison to pure GA (64%) and TA (73%), suggesting improved free radical scavenging due to synergistic effects. Antibacterial and antibiofilm assays against Escherichia coli and Staphylococcus aureus revealed that when [HMIm][Br] was combined with GA or TA, antimicrobial efficacy was enhanced specifically for S. aureus when compared to the individual components. The zone of inhibition reported in case of S. aureus (GA: 9 mm; [HMIm][Br] + GA: 18 mm; TA: 9 mm; [HMIm][Br] + TA: 14 mm) and E. coli (GA: 8 mm; [HMIm][Br] + GA: 15 mm; TA: 10 mm; [HMIm][Br] + GA: 10 mm). Molecular docking studies supported these findings, indicating binding affinity of ([HMIm][Br]) to bacterial proteins, S. aureus (−5.0 kcal/mol) and E. coli (−4.0 kcal/mol). These results highlight the potential of [HMIm][Br] in improving the solubility, stability, and bioactivity of polyphenols, making the combination a promising candidate for applications in pharmaceuticals, food preservation, and cosmetics. The study contributes to the development of sustainable and effective polyphenol-based formulations.

The necessity for sustainable wastewater treatment has become increasingly evident due to the depletion of freshwater resources and the prevalence of environmental pollution. Traditional wastewater treatment methods are often energy-intensive and may not meet stringent disposal standards. Recently, biological systems have gained attention as viable, eco-friendly, and sustainable alternatives for wastewater treatment and resource recovery. This study provides a comprehensive overview of the latest research on cyanobacterial-bacterial wastewater treatment systems, the factors that influence their effectiveness, and the challenges associated with resource recovery from the resulting biomass. In our investigation, four wastewater samples were collected from various sources, namely, municipal drainage, spice industry, aquaculture pond, and fish processing industry, denoted as W1, W2, W3, and W4 from different locations of Bhubaneswar, Odisha. The cyanobacteria and bacteria used in this study were identified as Lyngbya hieronymusii and Lysinibacillus macroides, respectively. Both organisms were cultured in the wastewater samples under axenic and co-cultured conditions. The analysis of physico-chemical parameters revealed a significant reduction (80%–97%) in nitrate, phosphate, ammonia, chloride, total hardness, dissolved oxygen (DO), biochemical oxygen demand (BOD), and chemical oxygen demand (COD) following treatment. Notably, a two-fold increase in cyanobacterial growth was observed under co-cultured conditions compared to axenic conditions in sample W4 FME. The interaction between cyanobacteria and bacteria is crucial for nutrients and pollutants removal from wastewater, with a real-time increase in the production of cyanobacterial biomass and bioactive compounds, highlighting its potential applications in environmental biotechnology.

Nanoplastics (NPs) are increasingly recognized as persistent contaminants in aquatic ecosystems, raising critical concerns for environmental and ecological health. This article synthesizes current knowledge on the impact of NPs in freshwater and marine environments. The contrasting behaviors of NPs across lakes, rivers, and oceans are discussed alongside transformation processes, including photodegradation, biodegradation, and chemical alteration, which contribute to their long-term persistence. Special attention is given to ecotoxicological impacts on aquatic organisms, including bioaccumulation, biomagnification, and cellular-level toxicity, with evidence of oxidative stress, reproductive impairment, and neurotoxicity. Advances in detection and characterization methods, from spectroscopic and microscopic techniques to mass spectrometry-based approaches, are outlined to address analytical challenges. Emerging strategies for nanoplastic removal, including membrane processes, advanced oxidation, and biodegradation, are also considered. Collectively, this work provides an integrated perspective on the environmental dynamics, toxicological risks, and management approaches for nanoplastics, guiding future monitoring and mitigation efforts.

Plastics are widely used due to their low cost and versatility, but their durability has led to severe environmental consequences. Accumulating in urban waste and natural waterways, plastics degrade into microplastics, now detected in nearly every aquatic environment. These particles pose serious ecological risks as they are ingested by fish and wildlife, causing physiological stress and enabling the transfer of toxic substances through food webs, including to humans via seafood consumption. Microplastics also act as carriers for pesticides, heavy metals, and microfibers, increasing chemical exposure. Although detection technologies have improved, research is limited by inconsistent methodologies and the absence of global standards. This review summarizes current knowledge on microplastic sources, environmental behavior, ecological impacts, and human health risks, while identifying key gaps related to biodegradable alternatives, standardized monitoring protocols, and integrated policy frameworks essential for safeguarding aquatic ecosystems and public health.

The depletion of limited natural resources and the need for strict environmental policies have catalyzed a shift toward sustainable and circular resource management, including the recovery of valuable nutrients like phosphorus and nitrogen from wastewater. This review evaluates the current state-of-the-art technologies for nutrient recovery, focusing on their economic viability. By analyzing these technologies, the review article gives a novel perspective on their potential to reduce reliance on finite resources, create a sustainable, resource-efficient societal network, and contribute toward the circular economy. Our current study highlights the economic potential and implementation challenges, offering a comprehensive overview of how nutrient recovery from wastewater can be a crucial strategy for closing a nutrient loop.

This research addresses the significant issue of arsenic contamination in water sources by inventing an environmentally friendly absorbent material derived from durian peels, an abundant agricultural waste in Thailand. The study compares different methods of producing activated carbon (AC) from durian peels: physical activation (DP-AC1) using steam at 121°C and 32 psi pressure, and chemical activation using phosphoric acid (H₃PO₄) at 600°C (DP-AC2) and 800°C (DP-AC3). These ACs were evaluated against commercial activated carbon (CAC) for arsenic adsorption efficiency. The research examined iodine and methylene blue (MB) adsorption values, surface morphology, equilibrium time, pH and optimal adsorbent dosage. Results showed that durian peel AC produced by chemical activation at 800°C (DP-AC3) exhibited superior performance, with an iodine adsorption value of 803.52 mg/g, exceeding both CAC (750.19 mg/g) and the American Water Works Association standard (600 mg/g). Batch adsorption experiments revealed that DP-AC3 achieved a maximum As(III) removal efficiency of 89.72% under optimized conditions (pH 7, 3 g/L dosage, 120 min contact time), outperforming CAC (73.69%). Moreover, DP-AC3 reduced the residual arsenic concentration to below the regulatory threshold for industrial effluents, whereas CAC-treated water did not meet the same standard. These findings demonstrate the efficacy of phosphoric acid-activated durian peel carbon as a sustainable and economically viable adsorbent, offering a promising alternative to conventional materials for arsenic remediation and advancing the principles of the circular economy in environmental engineering.

Mechanistic understanding of the nitrogen cycle in natural freshwater systems, such as the Euphrates River, is critical for sustaining ecosystem services and environmental protection. A model framework of the biogeochemical processes of nitrogen dynamics has the potential to analyze system performance and could highlight the most effective solutions for water quality pollution. The dynamics of mineral nitrogen, including ammoniacal N (NH₄⁺+NH₃), oxidized N (NO₂⁻+NO₃⁻) and total mineral N (TIN) in the Euphrates River within Karbala city in Iraq, are investigated between April 2018 and September 2019. In this study, a system dynamics model is developed to examine the dynamics of mineral N and explore new insights for mitigation strategies. Findings obtained from this research indicate the ability of the system model to reproduce field observations reasonably. The root mean squared error (RMSE) value for the modeled and observed total ammoniacal N is 0.619 g N m⁻³, which reflects a best fitted description for the steady state concentration. A higher RMSE value observed for total oxidized N (3.591 g N m⁻³) could be attributed to the higher nitrifying capacity of the system than model predictions. Field observations and model predictions confirm that the NO₃⁻ is the predominant N form in the Euphrates River (2.64 ± 1.54 g m⁻³), suggesting the important role of metabolic pathways in N cycling in the river system. These findings are also supported by the changes in the hydraulic water budget and physicochemical responses. Research outcomes highlight the modeling framework as an important approach to improving knowledge of N dynamics, system analysis, and helping decision-making to explore best management practices in the Euphrates River.

The rapid development of the textile industry has led to an increasing discharge of dye effluents into the environment, posing a major environmental issue due to the recalcitrance and harmfulness of colorants. This work investigated the degradation of Methylene Blue (MB) through the persulfate-based process and evaluated its applicability for treating actual textile wastewater. The influences of pH, [Fe²⁺], and [S₂O₈²⁻] on MB removal were examined, and the process was further optimized using the Box–Behnken design (BBD) to systematically evaluate their interactive effects. The result revealed that the optimum condition for photocatalytic persulfate reaction for MB removal was at pH 3.07; Fe²⁺ concentration of 19.5 mM, and S₂O₈²⁻ concentration of 31.3 mM, the removal rate of MB was achieved at 95.33% after 60 min reaction. Under optimal conditions, the persulfate-based advanced oxidation process (AOP) demonstrated good performance in treating real textile effluent, attaining 83.97% COD removal and 90.00% color removal, thereby reaching Vietnam's national discharge standard for the effluent of the textile industry (QCVN 13-MT:2015/BTNMT, Column B). This study provides a novel and practical contribution by integrating single-factor evaluation with RSM optimization to identify key operational parameters governing persulfate activation and dye degradation.

The increasing demand for rare earth elements (REEs) in advanced technological applications, combined with the limited availability of primary resources, has intensified efforts to recover REEs from secondary sources. Spent NdFeB magnets, commonly found in hard disk drives (HDDs), represent a rich and promising source, containing approximately 30% of REEs. This study focuses on the comparative leaching studies between roasted and unroasted NdFeB magnet samples using HCl as lixiviant. Leaching experiments were systematically conducted to evaluate the influence of key process parameters: acid concentration, temperature, and leaching duration on the recovery of valuable metals. The unroasted sample achieved 99.9% REEs recovery; however, high iron dissolution indicated poor selectivity. In comparison, the roasted sample demonstrated higher selectivity, with recoveries of 96.9% for Dy, 95.4% for Pr, and 93.2% for Nd, while iron dissolution was limited. Leaching kinetic analysis of roasted magnet powder indicated that rare earth leaching kinetics followed a mixed control mechanism, with the activation energy calculated as 39.35 kJ/mol within the temperature range of 30–60°C.