Polytetrafluoroethylene (PTFE) is an attractive membrane material due to its superior chemical resistance, thermal stability and strong hydrophobicity. However, PTFE hollow fiber membranes are ...challenging to produce by conventional technique due to the high solvent resistance and high melt viscosity of PTFE. In this study, novel PTFE hollow fiber membranes composed of pure PTFE nanofibers were firstly fabricated via a scalable and environment-friendly method based on emulsion electrospinning with a non-rotating collector and followed by a high-temperature sintering process. The effects of PTFE/PEO mass ratio and sintering temperature on the morphologies and properties of the resulting membranes were investigated. The prepared PTFE hollow fiber membrane shows the excellent characteristics combining the advantages of both electrospun nanofibers membrane and hollow fiber membrane, such as high porosity (more than 82%), self-supporting and superhydrophobicity. The membrane sintered at 380 °C present the highest mechanical strength, which shows the tensile strength, Young's modulus, strain at break of 30.5 Mpa, 53 Mpa, and 315%, respectively. The permeate flux of the prepared PTFE hollow fiber membrane is about 4.6–8.8 times as that of the commercial PTFE hollow fiber membranes, as well as is approximately 3.2–11.6 times higher than the date of the reported PTFE hollow fiber membranes. Additionally, the prepared membrane shows high and stable flux in long-term and rising salinity experiments, indicating it is very promising for membrane distillation (MD) application and even for the treatment of hyper-saline wastewater.
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•Novel hollow fiber membranes composed of pure PTFE nanofibers.•Scalable and environment-friendly method was proposed.•Membranes are high porous, self-supporting and superhydrophobic.•3.2–11.6 times higher than the flux of reported PTFE hollow fiber membranes.•Stable and high flux in treatment of hyper-saline wastewater.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The effects of submerged macrophytes Ceratophyllum demersum L. restoration on different forms of phosphorus in overlying water, pore water and sediments were investigated under indoor condition, and ...the correlations between environment variables were also analyzed. The results showed that the concentrations of total phosphorous (TP), particulate phosphorus (PP), total dissolved phosphorus (TDP), soluble reactive phosphorus (SRP) in the overlying water were reduced by 73.21%, 83.78%, 70.04% and 71.94%, respectively. The effects on TDP and SRP in pore water were not significant and no effect was observed for TP and PP. However, the TP release rate from the sediment was significantly enhanced (p=0.008), along with the increase of decomposition rates of organic phosphorous (OP) (p<0.001) and the NH4Cl-P release rate (p<0.001). No significant differences for BD-P, NaOH-rP, HCl-P between the experimental system and control were found in the sediment.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Effective removal of mercury (Hg) pollutants from contaminated water/wastewater to prevent severe environmental pollution is of great significance due to the extremely high toxicity of Hg. In this ...study, granular biochar and gravel (control) were packed into intermittently aerated constructed wetland (CW) microcosms to treat Hg(Ⅱ)-containing wastewater over 100 d. The results showed that the biochar-filled CWs exhibited notably better Hg(Ⅱ) removal than the gravel systems by facilitating chemical and microbial Hg(Ⅱ) reduction and volatilization and promoting plant growth and Hg assimilation. More than ten times more Hg was absorbed by the plants (L. salicaria) in biochar CWs than in the gravel systems, with the roots acting as the major sink. In contrast, substrate binding in a predominantly oxidizable fraction was the dominant pathway for Hg removal in the gravel CWs. Biochar substrates also exhibited higher levels of COD, N and P removal, and Hg(Ⅱ) import impacted the removal of these pollutants only slightly. Filling material played a more crucial role than Hg input in shaping the microbial communities in the CWs. The proportions of some dominant genera, including Arenimonas, Lysobacter, Micropruina and Hydrogenophaga, increased in the presence of Hg, implying their tolerance to Hg toxicity and potential roles in Hg detoxification in the CWs. Granular biochar-based CW has high potential for treating Hg(Ⅱ)-contaminated wastewater.
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•Granular biochar-filled CWs were applied to treat Hg(Ⅱ)-containing wastewater.•Biochar substrates facilitated Hg volatilization and phytoremediation.•Biochar CWs were more effective in removing COD, N and P than gravel systems.•Hg(Ⅱ) input slightly decreased the nutrient removal efficiencies of CWs.•Effect of Hg on the microbial communities in CWs was related to substrate type.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
A new method for the synthesis of β-N-(γ-L(+)-glutamyl)phenylhydrazine is presented. This compound was prepared from L-glutamine and phenylhydrazine through a transpeptidation reaction of Escherichia ...coli γ-glutamyltranspeptidase although phenylhydrazine has been reported to be an inhibitor of the enzyme. The optimum reaction conditions were 60 mM L-glutamine, 300 mM phenylhydrazine, 40 U γ-glutamyltranspeptidase/ml, and pH 9 in approx. 800 ml. After 6 h at 37 °C, the product was obtained with a conversion rate of 93 % (mol/mol). γ-Glutamyltranspeptidase was reversibly inhibited only when phenylhydrazine was above 300 mM.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
A large quantity of surfactants (e.g., sodium dodecyl sulfate (SDS)) are discharged along with greywater especially during the COVID-19 pandemic, while information on the treatment of ...surfactant-containing greywater using eco-friendly constructed wetlands (CWs) and the impact of surfactants on CW systems has rarely been reported. In the present study, lab-scale CWs amended with a biochar substrate and operated in tidal flow (TF) mode were used to treat SDS-containing greywater. The results showed that the biochar-amended CWs removed NH4+-N significantly better (18.2–37.9%) than the gravel-only CWs (2.5–24.6%) but removed phosphorus (P) and COD less efficiently, and the feeding of SDS at 50 and 100 mg/L led to a notable decrease in N removal. TF not only notably improved the pollutant removal performance but also effectively eliminated SDS stress in the CWs (NH4+-N removal of 67.1–72.1%). Mean SDS removal efficiencies of 75.3–79.3% were obtained in the CWs. TF mode altered the microbial community structure and metabolic pattern and enhanced the abundance of functional bacteria related to N and P removal in the CWs. The bacterial community shifted considerably with SDS feeding, resulting in higher species diversity and more intensive co-occurrence network relationships. TF-CWs filled with composite substrates are highly feasible and promising for the treatment of SDS-containing greywater.
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•SDS-containing greywater was treated by constructed wetlands (CWs) with different setups.•SDS caused a dose-response reduction in nitrogen removal in flooded CWs.•Tidal flow (TF) mode notably enhanced CW treatment performance and eliminated SDS stress.•SDS feeding and TF enhanced microbial diversity and regulated community structure.•SDS feeding notably strengthened microbial interspecific interactions in the CWs.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Controlling nonpoint source pollution (NPSP) is very important for protecting the water environment, and surface-flow constructed wetlands (SFCWs) have been widely established to mitigate NPSP loads. ...In this study, the pollutant removal efficiencies, greenhouse gas (GHG) emissions, and chemical and microbial community properties of the sediment in a large-scale SFCW established beside a plateau lake (Qilu Lake) in southwestern China to treat agricultural runoff were evaluated over a year. The SFCW performed best in terms of nitrogen removal in autumn (average efficiency of 63.5% at influent concentrations of 9.3–35.4 mg L−1) and demonstrated comparable efficiency in other seasons (23.7–40.0%). The removal rates of total phosphorus (TP) and chemical oxygen demand (COD) were limited (18.6% and 12.4% at influent concentrations of 1.1 and 45.5 mg L−1 on average, respectively). The SFCW was a hotspot of CH4 emissions, with an average flux of 31.6 mg m−2·h−1; moreover, CH4 emissions contributed the most to the global warming potential (GWP) of the SFCW. Higher CH4 and N2O fluxes were detected in winter and in the front-end section of the SFCW with high pollutant concentrations, and plant presence increased CH4 emissions. Significant positive relationships between nutrient and heavy metal contents in the SFCW sediment were detected. The microbial community compositions were similar in autumn and winter, with Thiobacillus, Lysobacter, Acinetobacter and Pseudomonas dominating, and this distribution pattern was clearly distinct from those in spring and summer, with high proportions of Spirochaeta_2 and Denitratisoma. The microbial co-occurrence network in spring was more complex with stronger positive correlations than those in winter and autumn, while it was more stable in autumn with more keystone taxa. Optimization of the construction, operation and management of SFCWs treating NPSP in lake watersheds is necessary to promote their environmental benefits.
•Comprehensive environmental functions of a large-scale constructed wetland (CW) treating agricultural runoff were evaluated.•Moderate nitrogen removal was obtained, with the best efficiency in autumn, while COD and P removals were limited in the CW.•The CW was a hotspot of CH4 emissions and plant presence increased the CH4 emission flux.•A complex microbial co-occurrence network with strong cooperation was formed in spring, while the network was stable in autumn.•Suggestions for optimization of such CW systems were proposed.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Gravel-based subsurface-flow constructed wetlands (CWs) amended with a walnut shell (WS) substrate were established to treat synthetic acid mine drainage (AMD) in this study, and artificial domestic ...wastewater (DW) and plant litter broth (PLB) were supplemented to enhance the performance. The CW media rapidly reached adsorption saturation with respect to metals (except Fe and Cr) without an external carbon source, while the addition of DW and PLB stimulated sulfate reduction activity and achieved efficient biogenic metal removal, primarily by the formation of hydroxide and sulfide precipitates and concomitant co-precipitation. The WS-amended CWs performed notably better than the control systems, not only in sequestering more metals and rapidly establishing favourable environments for biogenic metal abatement but also in supporting better growth of plants and functional microbes. The external organic carbon input greatly shaped the bacterial community compositions in the CWs, with substantial increases in the proportions of core functional populations involved in AMD biotreatment. Cooperation among Cellulomonas, Propioniciclava and sulfate-reducing bacteria (SRB), dominated by Desulfobulbus and Desulfatirhabdium, was the primary biogenic mechanism of AMD remediation in the CWs. Cellulosic waste-amended CWs with DW and PLB addition offer a promising eco-technology for AMD remediation.
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•Constructed wetlands amended with walnut shells performed better than those with gravel in AMD remediation.•Domestic wastewater and plant litter broth efficiently enhanced the treatment effectiveness.•Precipitation as hydroxides/oxides and sulfides was the dominant mechanism of metal removal.•External carbon increases the functional population abundances greatly.•Synergy among Cellulomonas, Propioniciclava and SRB was responsible for AMD bioremediation.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The ubiquitous presence of micro/nanoplastics (MNPs) in the environment poses high potential risks to living organisms and ecosystems. Wetlands are important sinks for MNPs, which can impact the ...ecological and environmental functions of wetland systems. However, the responses of greenhouse gas (GHG) emissions from wetlands to MNPs have rarely been evaluated. A multilevel meta-analysis was conducted to assess the effect of MNPs on GHG (CO2, CH4, and N2O) emissions from wetlands. The results showed that the presence of MNPs generally led to increases in GHG emissions from wetlands, especially N2O emissions. MNP type and exposure dose were the decisive factors influencing wetland GHG emissions, with CO2 and N2O emissions stimulated by biodegradable MNPs made of polylactic acid and by a high MNP dose of 1–2%, while polystyrene reduced CO2 and N2O emissions, and a low MNP dose of less than 0.5% increased CH4 emissions. CO2 emissions from the sediment of coastal wetlands were more sensitive to MNP pollution, while CH4 emissions from the sediment of freshwater wetlands were significantly increased by MNP pollution. Furthermore, microbial diversity and the number of carbon–nitrogen cycling functional genes associated with GHG emissions in wetlands were increased by MNPs. More research on the effect of MNPs on GHG emissions from wetlands over a longer time is needed, especially in real wetland ecosystems with aquatic organisms.
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•Microplastics (MPs) increase greenhouse gas (GHG) emissions from wetlands, especially N2O emissions.•MP type and dose significantly influence wetland GHG emissions.•The effect of MPs on GHG emissions depends on wetland type.•MPs increase the abundance of microbes related to GHG emissions in wetlands.•More studies on the impact of MPs on GHG emissions from wetland ecosystems are needed.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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•A process to directly regenerate spent LiNi1/3Co1/3Mn1/3O2 is demonstrated.•This process incorporates mechanochemical activation and solid-state sintering.•This method can restore ...the layered structure and improve lithium ion diffusion.•Secondary pollution will not be introduced in this regeneration process.•The economic viability of this method is better than a metallurgical process.
The production of lithium-ion battery is around 9100 million sets in 2016 and is believed to further increase consecutively. This fact triggers the generation of spent cathode materials which contain metals of both valuable and hazardous. Their recycling corresponding to life cycle sustainability of lithium-ion battery has attracted significant attention. However, most technologies for recycling waste lithium-ion batteries are dependent on metallurgical based processes where secondary pollution is inevitable. This research demonstrates a process to directly regenerate LiNi1−x−yCoxMnyO2 cathode material by incorporating methods of mechanochemical activation and solid-state sintering, which can restore the layered structure and improve the lithium ion diffusion without introducing extra impurities. By understanding the effects of sintering temperature, the optimal conditions for direct regeneration of cathode materials with obvious improvement on electrochemical performance can be obtained. As a result, this research proves the possibility of direct regeneration of nickel-containing waste cathode materials with minimized chemical consumption.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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•Tidal operated biofilters were investigated to treat heavily polluted river water.•Inorganic materials are efficient in NH4+-N and P removal.•Fibrous carrier is preferable for NO3−-N ...and TN removal.•Higher abundance of denitrifiers developed in organic substrate-based systems.
In this study, biofilters (BFs) packed with inorganic (ceramsite and lava rock) and organic (fibrous carrier and biological ball) materials were applied in a tide-flow mode at three flooded/drained (F/D) time ratios (16/8 h, 12/12 h and 8/16 h) to treat heavily polluted river water. The results showed that higher ammonium and phosphorus removals were achieved with BFs filled with ceramsite (95–97% and 76–77%) and lava rock (87–92% and 84–94%), while fibrous carrier-packed BFs obtained better total nitrogen removal (37–44%). Moreover, the F/D time ratio of 16/8 h was slightly preferable for pollutant removal. High-throughput sequencing analysis illustrated that the relative abundance of potential denitrifiers that developed on organic media was much higher than those on inorganic substrates. The results indicated that the combination of inorganic materials and fibrous carriers as substrates could be an effective strategy for enhancing overall pollutant removal in BFs.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
