Environmental Technology最新文献

The ubiquity of electronic devices has made them indispensable in daily life. Nevertheless, this high priority leads to a surge in electronic waste, or e-waste, which is extremely dangerous for the environment and human health. E-waste contributes to environmental pollution and threatens ecosystems and human health. Management of recycling methods and efficient e-waste is crucial to lower these dangers. Traditional recycling techniques are effective, but often release harmful pollutants. The present study has attempted to use the metal-resistant Exiguobacterium himgiriensis isolated from e-waste, such as the Printed Circuit Board (PCB), to investigate its efficiency in removing heavy metals from these substrates. By using ICP-OES, it has been found that this species of bacterium recovered different types of metals (Co 84.67%, Ni 83.25%, Pb 80.17%, Cu 80.06%, Zn 76.71%, Al 76.13%, Fe 71.74%, and Ag 64.97% respectively) within 5 days under laboratory conditions. Detecting structural and functional group changes in the control PCB and bioleached residue by the FT-IR, FE-SEM, EDS, and XRD techniques confirms the evidence of bioleaching. Bacteria can increase their dissolving capacity and decrease surface tension by chemically changing metals. E. himgiriensis bioleaches PCB samples for 5 days, resulting in rougher, uneven surfaces with fractures and fissures. FT-IR spectroscopy reveals the bacterium's impact on metals, particularly Si, O, and Fe. This study could help reduce environmental pollution and health risks associated with e-waste by developing an economical and environmentally friendly method for bioleaching different metals in PCB.

With the increasing generation of spent lithium-ion batteries (LIBs), there is an urgent need for efficient and environmentally friendly recycling methods. Compared to traditional pyrometallurgical and hydrometallurgical processes, deep eutectic solvents (DESs) offer advantages for recycling valuable metals from spent LIBs, including better biocompatibility and high recovery efficiency. However, complex procedures, long processing times, and solvent regeneration remain challenges. To address these limitations, we propose a streamlined recycling approach using a DES synthesised from guanidine hydrochloride (GUC) and tartaric acid (TA). This method promotes Li enrichment in the leachate while Co, Ni, and Mn mainly precipitate. Adding ethanol as an antisolvent enhances crystallisation and precipitation, producing Li-rich solutions and precursors containing only trace amounts of Li for Co-Ni-Mn (NCM) cathodes. Subsequent carbonisation converts Li into Li₂CO₃, which is then mixed with precursors in controlled ratios and subjected to high-temperature solid-state sintering to regenerate NCM cathode materials. Notably, ethanol and the DES are recovered by distillation with recovery efficiencies of 91.6% and 80%, respectively. This optimised process achieves leaching of NCM cathode materials under mild conditions and significantly improves the separation efficiency between Li and Co/Ni/Mn through a simplified workflow. Overall recovery efficiencies reach 97.51% for Li, 98.57% for Ni, 100% for Co, and 97.24% for Mn in regenerated NCM materials. This study presents a green, efficient, and simplified method for recovering valuable metals from spent LIB cathode materials.

The environmental spread of antimicrobial resistance genes (ARGs) through the use of animal manure in agriculture has become a significant concern. This study investigated the impact of applying swine manure treated through biodigestion on the spread of ARGs in agricultural soils in the Midwest region of Brazil. Samples of untreated and treated manure, fertilized soil, and unfertilized soil were collected from three piglet production units. Bacterial communities and ARGs were characterized through metagenomic sequencing and bioinformatics. Bacterial profiles in fertilized and unfertilized soils were highly similar across all farms. In contrast, biodigestion reduced the total number of ARGs in treated manure. Of the 399 ARGs detected in fertilized soils, 67% were also found in unfertilized soils, and 12% were shared exclusively with treated manure. The presence of numerous ARGs in unfertilized soils highlights the role of environmental dissemination routes, such as runoff, dust, or wildlife, in shaping soil resistomes even in areas without manure application. These findings suggest a stable bacterial and resistome profile in soils, regardless of manure application. Although antimicrobial residues were not evaluated, the results reinforce the need for responsible antibiotic use and effective manure management to minimize environmental ARG dissemination.

An investigation was conducted to evaluate hydraulic performance and chemical clogging of the concrete permeable reactive barrier (PRB) used to treat acid mine drainage (AMD). The pervious concrete PRB system is an emerging technology for AMD treatment. In the present study, pervious concrete mixtures were prepared at a 0.27 water/cementitious ratio using CEM I 52.5R cement with or without 30% fly ash and 9.5 mm granite aggregate. The AMD types used were obtained from a gold mine and from a coal mine. Porosity and permeability properties of the pervious concretes were measured before and after use to treat AMD. Subsequently, 2D slice image analyses were done using X-ray microcomputed tomography (microCT). It was found that the heavy metals comprising Al, Zn, Fe, Mn, Mg, Ni and Co, were removed at the high removal efficiency (RE) levels of 70-100%. Interestingly, critical reductions in porosity (P-crit) and permeability (K-crit) values were utmost at a short distance of 75 mm from the entrance, forming bottleneck clogging. Results showed that chemical clogging that ensued progressively during the experiment, adversely gave values of up to 30-40% reduction in RE values, up to 30-40% reduction in P-crit and 80-90% reduction in K-crit. MicroCT analysis of pore connectivity confirmed the occurrence of bottleneck clogging in the column reactors. Further studies are needed to investigate the long-term adverse impacts of chemical clogging that could potentially be employed to determine the PRB's longevity.

Excessive phosphorus discharge into lacustrine systems was recognized as a primary factor for eutrophication, significantly disrupting the ecological equilibrium of freshwater ecosystems. Effectively controlling endogenous phosphorus release from sediment reservoirs constitutes a fundamental prerequisite for mitigating this environmental challenge. In this study, a sediment microbial fuel cell (SMFC) was developed to address the challenges of sediment-bound phosphorus mobilization. Sediment Total Organic Carbon (TOC) removal in CC-FA-0.2 yielded 2.25 times greater than the control, indicative of aromatic and fulvic acid degradation. Phosphorus in interstitial water decreased by 66% in closed-circuit (CC) reactors, with sequential fractionation revealing enhanced iron-bound phosphorus (BD-P) retention in sediment (105% increase in CC-FA-0.05 vs. versus control). Fe(Ⅲ) redox cycling under SMFC operation maintained higher Fe(Ⅲ) retention (58-54% vs. 51-52% in open-circuit), critical for phosphate immobilization. Microbial profiling identified Proteobacteria (20.41%) and Desulfobacterota (20.41%) as dominant phyla, with genera like Geobacter and Sideroxydans synergistically driving Fe(Ⅲ)/Fe(Ⅱ) cycling and extracellular electron transfer. This study establishes a novel bioelectrochemical strategy based on fulvic-iron synergy, which drive a sustainable electrode-iron-humus redox cycle. This process offers a highly effective and sustainable approach for the simultaneous immobilization of sediment phosphorus and removal of organic pollutants in situ.

A laboratory-scale anaerobic membrane bioreactor (AnMBR) for landfill leachate (LFL) was operated to investigate the effects of nano zero-valent iron (nZVI) (without nZVI addition, 50-300 mg/L) on contaminant removal and membrane fouling. nZVI can be a potential additive to improve AnMBRs' performance by regulating LFL treatment, microbial community structure, and especially membrane fouling. Therefore, this study evaluated the role and effectiveness of nZVI in enhancing AnMBRs' performance for wastewater treatment and membrane fouling mitigation. Results show that nZVI addition could improve AnMBR performance in removing pollutants and reducing membrane fouling. The optimal condition was found to be nZVI at 100 mg/L, corresponding to a membrane fouling rate of 0.012 mbar/min. However, since membrane fouling rate worsens at higher concentrations, the optimal nZVI concentration for pollutant removal was determined to be 200 mg/L. The results indicated removal efficiencies of 68% for chemical oxygen demand (COD), 31% for colour, and 47% for dissolved organic carbon (DOC). As a result, transmembrane pressure (TMP) decreased by 68%, and permeate flux showed a slight improvement at 100 mg/L nZVI. Additionally, adding nZVI reduced the ratios of protein to polysaccharide in both extracellular polymeric substances (EPS) and soluble microbial products (SMP), thereby mitigating membrane fouling. Firmicutes, Bacteroidetes, and Proteobacteria, which showed relatively high abundance, played important roles in pollutant removal in LFL. Also, bacteria associated with membrane fouling were identified as Alphaproteobacteria, Sphingobacteria, and Flavobacteria in the AnMBR. Results indicate that nZVI addition can enhance AnMBR performance in both pollutant removal and membrane fouling reduction.

Membrane filtration is a safe and sustainable water treatment method; however, membrane fouling remains a major challenge that limits its broader application. Modified membranes for fouling mitigation have been extensively studied, including photocatalyst incorporation for organic matter degradation and biofouling control. However, no commercially available photocatalytic membranes exist to date, possibly owing to the lack of understanding of their properties. Furthermore, conventional microbiological test methods commonly used in membrane research are insufficient for accurately assessing membrane antibiofouling properties. Mixed-matrix dual-layer membranes with varying concentrations of zinc oxide nanoparticles were prepared and characterized using multiple testing approaches. Despite achieving >99.999% reduction in cultivable Escherichia coli, viability assays revealed that only half of the cells were dead, with the rest entering a viable but nonculturable (VBNC) state and forming microcolonies, resulting in misleading CFU-based results. Additionally, Pseudomonas aeruginosa biofilm formation was evaluated using fluorescence staining to assess extracellular polymeric substance (EPS) production. While P. aeruginosa survived and multiplied on the photocatalytic membranes, biofilm maturation was inhibited, with EPS protein production reduced by up to 84% compared with the unmodified reference.

This study developed a sustainable bio-adsorbent derived from rice straw carboxymethyl cellulose (CMC) and evaluated its efficiency in improving canal water quality for agricultural reuse. The synthesized CMC exhibited high solubility with a degree of substitution of 0.67. Batch adsorption experiments identified optimal conditions for manganese (Mn²⁺) removal at pH 6, 2.0 g L⁻¹ dosage, and 10 min contact time, achieving 97.0% removal efficiency and an adsorption capacity of 10.54 mg g⁻¹. The adsorption process followed the Freundlich model (R² = 0.9501), indicating heterogeneous multilayer adsorption. To assess field applicability, a pilot-scale multi-stage filtration system - comprising sand, activated carbon, and CMC columns - was operated for 101 days at the Rangsit Prayurasak Canal. The system effectively reduced BOD₅ (85.4% ± 4.5%), Mn²⁺ (81.5% ± 3.6%), chloride (48.7% ± 3.68%), and salinity (46.3% ± 9.8%), producing treated water that met Thailand's Type III surface water standard for agricultural reuse. This work is the first to demonstrate the field-scale use of rice straw-derived CMC in a modular filtration system under actual canal conditions. The results highlight the dual benefits of agricultural waste utilization and practical water quality improvement, offering a technically feasible and low-cost solution for decentralized water treatment in agricultural communities.

ABSTRACTThe volumetric oxygen mass transfer coefficient ($k_{L}a$) is a critical parameter in the design, scale-up, and operation of bioreactors. In this study, a fully automated dynamic method was developed for determining $k_{L}a$, eliminating manual intervention and ensuring reproducible and reliable estimates. The approach includes a probe response-time correction and was validated under different operational conditions in an aerated stirred system. The influence of two representative pollutants was evaluated: phenol and benzalkonium chloride (BAC). While phenol produced a small enhancement (≈18%) of the overall $k_{L}a$, BAC caused a reduction in $k_{L}a$, mainly due to its pronounced effect on the surface mass transfer coefficient ($k_L{a}_S$). To the best of our knowledge, this work provides the first experimental evidence of BAC effects on oxygen transfer in bioreactors. These results expand the current understanding of how pollutants can simultaneously act as metabolic inhibitors and as modifiers of gas-liquid mass transfer, with significant implications for optimising aeration strategies in biological wastewater treatment.