Environmental Technology最新文献

Chromium (Cr) contamination represents a risk to the biodiversity of ecosystems, requiring the application of remediation processes for its recovery. One form of bioremediation can be done by bacteria resistant to hexavalent chromium (Cr(VI)). In the present study, the rhizobacterium Exiguobacterium indicum was isolated from the aquatic macrophyte Hymenachne grumosa, collected in the Santa Bárbara channel, located in southern Brazil. The Cr(VI) removal capacity and the response of oxidative stress biomarkers were analysed, in addition to the optimal pH and temperature conditions for maximum removal. The minimum inhibitory concentration of growth (MIC) of the isolate was 400 mg L^-1 of Cr(VI) and the results showed that E. indicum HG8 was able to grow and remove Cr in a wide range of incubation temperatures (20-45°C) and pH (5.0-9.0), evidencing its ability to adapt to different factors. The ideal conditions for cultivation and removal of Cr(VI) were verified at pH 6.0 and at 30°C. E. indicum HG8 was able to efficiently remove 99.6% of Cr(VI) and 89.4% of total Cr in 24 h of incubation. The increase in malondialdehyde levels in the extracellular extract demonstrates that there was lipid damage, in parallel with the increase in the adaptive response of antioxidant enzymes, indicating that oxidative stress was established. The data suggest that E. indicum HG8 possibly altered the permeability of the cell membrane, forming a kind of barrier.

Heavy metal contaminated soils have attracted worldwide attention, and there is a growing interest in the use of detergents to remediate heavy metal contaminated soils. In this study, the response surface methodology was used to determine the optimal drenching parameters by combining the interaction between the factors and the pollution safety index. The elution of heavy metals by the two-step elution method and the mixed elution method was investigated under optimal conditions (77.66 mmol.L^-1 MGDA, 145.01 mmol.L^-1 HH, pH 3.29, 90 min, S/L = 1:10, 25 °C). The results showed that the mixed solution was more effective in the elution of heavy metals, and the removal of lead, copper and nickel was 8.11%, 16.27% and 1.36%, respectively. The different forms of heavy metals were extracted by the modified Tessier method after water washing, and the results showed that the iron-manganese oxide-bound and carbonate-bound fractions of Pb, Cu and Ni were significantly reduced after water washing. Among them, the carbonate-bound state of Pb, Cu and Ni decreased by 90.30, 256.85 and 4.00 mg.kg^-1, respectively; the ferromanganese-oxidised state of Pb, Cu and Ni decreased by 531.00, 1493.33 and 48.74 mg.kg^-1, respectively; before and after drenching MCSI decreased by 10.85% compared with that before drenching. FTIR analysis of heavy metals after water washing showed that the mixture had no significant effect on soil properties after water washing. The above results indicated that the mixture of HH and MGDA can be used as a washing solution for heavy metal contaminated soil.

Azoles are widely employed as copper corrosion inhibitors in the semiconductor industry but pose environmental concerns due to their poor biodegradability and toxicity toward nitrifying microorganisms. Their occurrence in effluents highlights the need for effective treatment strategies. Here, four advanced oxidation processes (AOPs) - Fenton, UV/Fenton, UV/H₂O₂, and UV/persulfate processes - were systematically evaluated for the degradation of 1,2,4-triazole (TZ), a representative azole, in both lab-prepared and actual semiconductor wastewater collected immediately downstream of chemical mechanical planarization (CMP) manufacturing processes. While all three UV-assisted processes achieved complete degradation of 0.72 mM TZ from lab-prepared wastewater within 30 min, the UV/persulfate process exhibited the fastest kinetics (pseudo-first-order rate constant of 0.38 min^-1). However, in this semiconductor wastewater with 0.33 mM TZ, the UV/Fenton process exhibited the fastest kinetics and the highest TOC removal rate, underscoring the strong influence of matrix constituents. Given the high volume of this semiconductor wastewater, the potential of implementing a pre-concentration step was evaluated. Adsorption studies revealed that Fe(II)-zeolite exhibited the highest affinity for TZ, though its overall capacity was too low for practical pre-concentration. These findings provide practical guidance for optimising oxidation-based treatment strategies specifically for azole-containing semiconductor wastewater.

Benzo[α]pyrene (BaP) is a persistent organic pollutant that is notoriously difficult to remove. Here, we report the isolation of a novel BaP-degrading probiotic, Enterococcus faecium MA-4, from Kefir grains. Four factors for degradation of BaP by MA-4 were obtained through single factor test: pH 7, temperature 37°C, BaP concentration 10 mg L^-1, inoculum size 15%. Employing a Box-Behnken design within response surface methodology, the study investigated the impact of pH, temperature, BaP concentration, and inoculum size on the degradation rate of BaP by MA-4, aiming to enhance its degradation kinetics. The results revealed that the inoculum size was the predominant factor affecting degradation. Under optimal conditions, pH 6.5, an initial BaP concentration of 7 mg L^-1, a temperature of 35°C, and an inoculum size of 10%, the degradation rate of BaP by MA-4 was enhanced to 61.52%. Analysis of Variance confirmed the model's accuracy with a significant F-value of 12.03 at p < 0.0001 while the quadratic regression model showed a high R² value 0.9232. R²adj (0.8465) closely matches R²pred (0.6506). Adeq Precision(10.986) and Lack of Fit (F-value = 0.99) both demonstrate the reliability of the model. The probiotic MA-4 effectively degrades BaP, showing promise for food-grade applications in BaP mitigation. However, the application of Enterococcus faecium requires rigorous safety assessment due to their potential as opportunistic pathogens. This study provides key theoretical and practical guidance for the probiotic-based remediation of BaP in foodstuffs.

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.

Silicon-based solar photovoltaic (PV) panels are the most widely deployed technology for renewable electricity generation. However, after their 25-30 year service life, large volumes of end-of-life (EoL) panels accumulate, creating significant waste management challenges. Conventional recycling methods are energy-intensive and economically unattractive, leading to landfilling as the most common disposal route. This practice raises environmental concerns due to the potential leaching of toxic metals such as lead (Pb) and zinc (Zn). In this study, we propose a sustainable recycling strategy that incorporates EoL PV panels into concrete production. Aluminium frames and junction boxes were first removed from the panels, and the remaining laminates were shredded and sieved into three size fractions. The intermediate fraction was used as sand replacement in concrete. Heavy metal leaching was evaluated using the Toxicity Characteristic Leaching Procedure (TCLP), while the environmental impacts of landfill disposal and this recycling approach were compared using Life Cycle Assessment (LCA). TCLP results showed that Pb and Zn concentrations in this concrete were below detectable limits, whereas 3.21 mg/L of Pb and 7.34 mg/L of Zn leached from crushed laminates. LCA results indicated that landfilling imposed high environmental burdens, particularly in marine ecotoxicity (5.36E + 05 kg 1,4-DCB) and global warming potential (2.86E + 03 kg CO₂ eq.), while concrete recycling achieved reductions across all 18 impact categories, including a 69.8% decrease in non-carcinogenic human toxicity. These findings demonstrate that incorporating solar waste in concrete effectively immobilizes hazardous metals and offers a sustainable, low-impact recycling route for PV waste, significantly outperforming landfill disposal.

Mycoremediation, the application of fungi for pollutant degradation, offers a sustainable solution for bioremediating contaminated environments. In mixed microbial settings, microbial competition can influence the efficiency of fungi by modulating pollutant degradation and nutrient availability. We investigated the bioremediation potential of boreal white-rot fungi (WRF) in fiberbank sediments, targeting organic pollutants such as polycyclic aromatic hydrocarbons (PAHs) and potentially toxic elements (PTEs). Previously isolated and identified thirteen WRF species were screened in sterilized and unsterilized substrates to evaluate the effects of microbial interactions on pollutant degradation and metal uptake. Key findings revealed that unsterilized fiberbank material supported superior PAH degradation, with Trametes hirsuta achieving up to 94% removal, suggesting synergistic interactions between WRF and native microbial communities. Conversely, sterilized substrates enhanced PTE uptake, with Phlebia tremellosa demonstrating significant accumulation of cadmium, bioconcentration factor (BCF) of 5.56 in sterile conditions and 0.85 in unsterile conditions, and lead, BCF of 1.65 under sterile conditions, and 0.38 for unsterile conditions, this enhanced accumulation might be due to reduced microbial competition. Statistical analyses confirmed significant differences (p < 0.001) in pollutant removal and metal uptake between the two substrate conditions. These results underline the importance of tailoring bioremediation strategies to substrate conditions. A dual approach, employing unsterilized substrates for organic pollutant degradation and sterilized substrates for metal accumulation, emerges as a promising framework. Future applications could focus on large-scale implementation of these strategies to rehabilitate industrially contaminated sites like fiberbanks, balancing ecological sustainability with remediation efficacy.

The effects of different condition of low-intensity ultrasound on denitrification system was investigated. The effects on the characteristic of denitrifying bacteria were analyzed by measuring the electron transport system activity (ETSA) and extracellular polymeric substances (EPS). Also, the changes in the secondary structure of membrane proteins and lipids were analyzed by Fourier Transform Infrared (FTIR) spectroscopy and explored by second-order derivative fitting using OMNIC and Peakfit software. The results showed that low-intensity ultrasound could improve the mass transfer rate of cells by changing the secondary structure of protein lipid and improving the permeability and fluidity of the membrane. Vacuolization in the cytoplasm, accompanied by cell membrane damage was observed in transmission electron microscope (TEM), which meant ultrasound could disrupt cell membrane structure. ImageJ was employed to analyse TEM images, quantifying the membrane thickness via the ruler tool, it was found that the thickness of cell membrane decreased significantly after ultrasound.

The humic substances (HS) extracted from sludge provide a promising, cost-effective, and environmentally friendly alternative to traditional leaching agents for the remediation of arsenic (As) contaminated soil. Therefore, this paper investigates the remediation of As-contaminated soil using HS extracted from composted sludge. The HS solution extracted using NaOH solution is SHS, and the HS solution extracted applying sodium hydroxide sodium pyrophosphate is MHS. The effectiveness of these HS agents was compared with that of other fulvic acids, considering factors such as HS concentration, pH, liquid-to-solid ratio, leaching duration. The transformation of As species in soil was also explored. The results indicated that the optimal conditions for leaching were found to be SHS and MHS concentrations of 800 mg C/L, with pH of 11, liquid-to-solid ratio of 15:1, and equilibrium time of 24 h. Under these conditions, As removal efficiencies reached 35.46% for SHS and 41.36% for MHS. MHS showed superior performance, due to the use of a mixed NaOH and Na₄P₂O₇ solution. Both SHS and MHS exhibited pseudo-second-order kinetics and conformed to the Elovich model, indicating the existence of complex heterogeneous diffusion. The leaching process influenced the behaviour of coexisting metals such as Fe and Al, which disrupt their binding with As, promoting its release. Repeated leaching significantly improved the removal efficiency of As, with MHS demonstrating the highest effectiveness. The study supports the use of HS extracted from municipal composted sludge as a cost-effective, environmentally friendly approach for As-contaminated soil remediation.