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The disinfection of pathogenic microorganisms in water treatment by peracetic acid (PAA)-based advanced oxidation processes (AOPs) has been gaining increasing concern. In this work, the inactivation mechanism, influencing factors ...
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The disinfection of pathogenic microorganisms in water treatment by peracetic acid (PAA)-based advanced oxidation processes (AOPs) has been gaining increasing concern. In this work, the inactivation mechanism, influencing factors and regrowth of two pathogenic Aspergillus species in the system of CuO-activated PAA were studied for the first time. The k values of A. niger and A. flavus inactivated by PAA/CuO system were 3.9 and 2.1 -fold higher than those inactivated by PAA alone. PAA concentration and CuO dose were positively correlated with the inactivation efficiency, while humic acid and pH were negatively correlated. The main active species that contributed to the inactivation of fungal spores in PAA/CuO system were center dot OH, CH3C(O)OO center dot and 1O2. PAA/ CuO system had more intense oxidative stimulation and more serious damage to fungal spores according to the analysis of cell membrane integrity and intracellular ROS levels. In addition, the PAA/CuO system was less impacted by the water matrix and kept a good inactivation efficiency in real water samples. The regrowth po-tential of fungal spores after disinfection was also reduced in PAA/CuO system so as to avoid the risk of biologicalregrowth. This study provides a feasible PAA-based advanced oxidation method for activating PAA and inacti-vating fungal spores.
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Most of the reservoirs or lakes will form a metalimnetic oxygen minimum (MOM) with the characterization of a substantial fraction of dissolved oxygen (DO) depleted below the epilimnion. The effect of intracellular organic matter (...
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Most of the reservoirs or lakes will form a metalimnetic oxygen minimum (MOM) with the characterization of a substantial fraction of dissolved oxygen (DO) depleted below the epilimnion. The effect of intracellular organic matter (IOM) of algal cells transformed under MOM conditions is completely different from that of the original IOM on water quality. In this study, the IOM changes of Microcystic aeruginosa under different MOM conditions and its related disinfection by-products formation potentials (DBPFPs) were investigated by changing the pres-sure and DO concentration of MOM. Total Fmax increased slightly and then decreased under different pressure conditions, finally decreasing by no more than 22.0%. Under aerobic condition, dissolved organic carbon (DOC) and total Fmax decreased significantly, and decreased by 60.4% and 38.8% within the first 2 days. The results of specific UV absorbance (SUVA) and UV250/UV365 indicated that aromatic compounds and average molecular weight of IOM were gradually increased under different MOM conditions. The total DBPFPs increased firstly and then decreased under different pressure conditions, and finally decreased by 26.2%-33.1%. The decrease of total DBPFPs was significantly higher under aerobic condition than that under anoxic condition, which finally decreased by 64.5%. Redundancy analysis showed that the fluorescence parameter (protein-like and humic-like fluorescence) could be expected as an index to predict the DBPFPs. Moreover, the results revealed that with the decrease of DO, the activity and diversity of natural microbial consortium decreased, which prevented the further degradation and utilization of organic matter by natural microbial consortium. Therefore, lower DO was a key player for the deterioration of water quality under MOM conditions.
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Pre-ozonation is an effective pretreatment tactic for mitigating fouling of ultrafiltration (UF) membrane in water and wastewater treatment, but the compatibility of polymeric UF membranes with residual ozone remains unclear. In t...
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Pre-ozonation is an effective pretreatment tactic for mitigating fouling of ultrafiltration (UF) membrane in water and wastewater treatment, but the compatibility of polymeric UF membranes with residual ozone remains unclear. In this study, effects of long-term ozone exposure on properties and performance of polyvinylidene fluoride (PVDF) UF membrane reinforced by polyethylene terephthalate (PET) layer were systematically investigated. The exposure intensities were designed to simulate ozone exposure at 0.1 mg/L for 0.5-5 years. Chemical composition analysis suggested that the hydrophilic additives, such as possibly polyvinyl pyrrolidone (PVP), was gradually degraded and released from the membrane, whereas the PVDF matrix exhibited fairly good ozone resistance. Ozonation resulted in increase of pore size and decrease of surface hydrophilicity, which can be attributed to oxidation and dislodgement of hydrophilic additives. Accordingly, long-term ozonation led to moderate changes in performance factors, including increase of membrane permeability by 34%, decrease of retention ability by 21.8%, increase of organic fouling propensity. It is worth noting that membrane tensile strength suffered substantial decrease after ozonation, probably due to ozonation of the PET support layer. Overall, it seems that the PVDF functional layer exhibited good ozone resistance, but the PET support layer was the Achilles' heel of the reinforced PVDF membrane for integrating with pre-ozonation.
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With the crude oil exploration activities in the Shanbei oilfield of China, the risk of soil contamination with crude oil spills has become a major concern. This study aimed at assessing the bioremediation potential of the petrole...
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With the crude oil exploration activities in the Shanbei oilfield of China, the risk of soil contamination with crude oil spills has become a major concern. This study aimed at assessing the bioremediation potential of the petroleum polluted soils by investigating the expression of key functional genes decoding alkane and aromatic component degradation using an array of primers and real-time quantitative PCR (qPCR), and the functional microbiomes were determined using a combination of substrate-induced metabolic responses and high throughput sequencing. The results showed that the species that were more inclined to degrade aliphatic fraction of crude oil included Acinetobacter, Stenotrophomonas, Neorhizobium and Olivebacter. And Pseudomonas genus was a highly specific keystone species with the potential to degrade PAH fraction. Both aliphatic and PAH-degrading genes were upregulated when the soil petroleum contents were less than 10,000 mg/kg but downregulated when the oil contents were over 10,000 mg/kg. Bioremediation potential could be feasible for medium pollution with petroleum contents of less than 10,000 mg/kg. Optimization of the niche of Acinetobacter, Stenotrophomonas, Pseudomonas, Neorhizobium and Olivebacter species was beneficial to the biodegradation of refractory hydro-carbon components in the Shanbei plateau oilfield.
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Peroxymonosulfate(PMS)-based advanced oxidation process have been recognized as efficient disinfection processes. This study comprehensively investigated the role of sulfate radical (SO4 & BULL; ) and hydroxyl radical (& BULL;OH)driven disin...
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Peroxymonosulfate(PMS)-based advanced oxidation process have been recognized as efficient disinfection processes. This study comprehensively investigated the role of sulfate radical (SO4 & BULL; ) and hydroxyl radical (& BULL;OH)driven disinfection of bacteria and fungal spores by the PMS/metals ions (Me(II)) systems and modeled the CT value based on the relationship between survival and & int; [Radical]dt, with the aim to provide an accurate and quantitative kinetic data of inactivation processes. The results indicated that & BULL;OH played a more central role than SO4 & BULL; in the inactivation process, and bacteria were more vulnerable to radical attack than fungal spores due to the differences in antioxidant mechanisms and external structures. The k value of & BULL;OH -induced inactivation of E. coli was approximately 3-fold higher than that of A. niger, and the shoulder length of & BULL;OH -induced inactivation of E. coli was closely 52-fold shorter than that of A. niger after treated with the PMS/Co(II) system. The morphological and biochemical changes revealed that PMS/Me(II) treatment caused membrane damage, intracellular ROS accumulation and esterase activity loss in microorganisms. This study significantly improved the understanding of the contribution of radicals in the process of microbial inactivation by PMS/Me(II) and would provide important implications for the further development of technologies to cope with the highly resistant fungal spores in drinking water.
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Poor stability has long been a critical issue for lead halide perovskites that impeded their practical applications. To address this issue, we propose a novel and facile strategy to synthesize a highly stable fluorescent methylamm...
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Poor stability has long been a critical issue for lead halide perovskites that impeded their practical applications. To address this issue, we propose a novel and facile strategy to synthesize a highly stable fluorescent methylammonium lead bromide perovskite (MAPbBr(3))@PbBr(OH) composite through introducing a metal-organic framework (MOF) viz. a metal azolate framework (MAF-6) into the perovskite precursor solution during the ligand-assisted reprecipitation process. Different from the embedment of PNCs in MOFs, this strategy is achieved based on the hydrolysis reaction of PbBr2 triggered by a MOF combined with the confining synthesis of perovskite crystals inside the MOF cavity. The obtained MAPbBr(3)@PbBr(OH) composite exhibits high PLQY (similar to 45%) and enhanced stability against heat, UV light and especially various polar solvents. It is believed that the prepared MAPbBr(3)@PbBr(OH) with excellent solvent stability implies great potential as a green-emitting phosphor for luminescence application in a harsh environment, especially in a solvent system.
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A distributed solar heating system (DSHS) connects solar heat users who both produce and consume heat, taking advantage of the difference and complementarity in heat demand among users to improve system efficiency. The pipe networ...
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A distributed solar heating system (DSHS) connects solar heat users who both produce and consume heat, taking advantage of the difference and complementarity in heat demand among users to improve system efficiency. The pipe network of the DSHS has the characteristics of bidirectional flow, and the existing unidirectional network design method from heat source to users cannot be applied to the bidirectional-flow network. This paper developed an optimization model for the network layout and the pipe diameter by minimizing the total annualized costs (TAC). The model was solved using an improved integer-coding genetic algorithm, which realized the collaborative optimization of the network layout and pipe diameter. The same results were obtained by applying the exhaustive method and the proposed method for a case study, which verified the effectiveness of the proposed method. Compared to the conventional design method, the proposed optimization model resulted in a 4.9% savings in TAC. A parametric analysis showed that pipeline price affects design results when annualized network con-struction costs, operating costs and heat loss costs are comparable. The method proposed in this study can be used to effectively design the network of DSHS, and provides a reference for the further devel-opment of DSHS.(c) 2022 Elsevier Ltd. All rights reserved.
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The photodegradation of antibiotics and organic dyes in water in the current environment has attracted attention. However, its practical value in the river is poor because the efficient and recyclable photocatalysts are insufficie...
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The photodegradation of antibiotics and organic dyes in water in the current environment has attracted attention. However, its practical value in the river is poor because the efficient and recyclable photocatalysts are insufficient. Therefore, a novel ternary BiOBr/g-C3N4/Ti3C2Tx (BCT-x) hybrids were efficaciously prepared via the in-situ construction method for improving photodegradation of Tetracycline Hydrochloride (TC-HCl) and Rhodamine B (RhB) under Xenon lamp. The characterization results clarified that the combination of BiOBr and g-C3N4 could expand light absorption region. Meanwhile, the hybrids possessed accelerated carrier separation and migration ability due to the introduction of co-catalyst Ti3C2Tx with efficient electrical conductivity. The BCT-5 exhibited vintage photocatalytic activity for TC-HCl (97%, 60 min) and RhB (98%, 50 min). Photo-generated holes (h+) and superoxide radicals (center dot Oz) were the main active species. The Liquid Chromatography and Mass Spectrometry (LC-MS) analysis showed that TC-HCl could be photodegraded by BCT-5 into smaller molecular weight and non-toxic substances. A reasonable photocatalytic mechanism on BiOBr/g-C3N4/Ti3C2Tx was brought up. This study provides guidance for advancing the application of photocatalytic technology in water pollutant degradation.(c) 2023 Elsevier B.V. All rights reserved.
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A coaxial cylindrical double dielectric barrier discharge (DDBD) reactor with two separate discharge zone was designed and the role of its different discharge zones and reactive species were explored in toluene degradation. The in...
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A coaxial cylindrical double dielectric barrier discharge (DDBD) reactor with two separate discharge zone was designed and the role of its different discharge zones and reactive species were explored in toluene degradation. The inner tube (the space between the high voltage electrode and the inner barrier) had a higher gas temperature and reactive species concentration due to its stronger discharge intensity compared with the outer tube (the space between the inner and outer barriers). The two discharge zones exhibited similar toluene removal efficiency, whereas the mineralization rate of the inner tube exceeded that of the outer tube under 18-22 kV, and the result was opposite under 24-28 kV. The gas-flow direction had no significant effect on the toluene removal efficiency, but the mineralization rate of the down-flow reactor (23.7%-54.4%) exceeded that of the reverse-flow reactor (20.7%-45.5%). The inner and outer tubes mainly responsible for the initial degradation and further oxidation of toluene, respectively. The role of long-lived (N2 (A3 sigma + u ( ) ( ) short-lived (N2 C311 , N2 B311 , and atomic O (1D and 3P)) reactive species on toluene degradation and u g oxidation was analyzed. The plausible toluene degradation mechanism in the DDBD reactor was proposed based on the role of different discharge zones and reactive species. The finding herein is significant in the design, optimization and application of DBD reactors. ) and metastable O-2 (a1Ag and b1 & USigma;g+)) andoxidation was analyzed. The plausible toluene degradation mechanism in the DDBD reactor was proposed based on the role of different discharge zones and reactive species. The finding herein is significant in the design, optimization and application of DBD reactors.
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The coexistence of multiple pollutants and lack of carbon sources are challenges for the biological treatment of wastewater. To achieve simultaneous removal of nitrate (NO3--N) and cadmium (Cd2+) at low carbon to nitrogen (C/N) ra...
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The coexistence of multiple pollutants and lack of carbon sources are challenges for the biological treatment of wastewater. To achieve simultaneous removal of nitrate (NO3--N) and cadmium (Cd2+) at low carbon to nitrogen (C/N) ratios, 2-hydroxy-1,4-naphthoquinone (HNQ) was selected from three redox mediators as an accelerator for denitrification of heterotrophic strain Pseudomonas stutzeri sp. GF2 and autotrophic strain Zoogloea sp. FY6. Then, halloysite nanotubes immobilized with 2-hydroxy-1,4-naphthoquinone (HNTs-HNQ) were prepared and a bioreactor was constructed with immobilized redox mediator granules (IRMG) as the carrier, which was immobilized with HNTs-HNQ and inoculated with the two strains. The immobilized HNQ and the inoculated strains jointly improved the removal ability of NO3--N and Cd2+ and the removal efficiency of NO3--N (25.0 mg L-1) and Cd2+ (5.0 mg L-1) were 92.81% and 93.94% at C/N = 1.5 and hydraulic retention time (HRT) = 4 h. The Cd2+ was removed by adsorption of iron oxides (FeO(OH) and Fe3O4) and IRMG. The electron transport system activity (ETSA) of bacteria was improved and the composition of dissolved organic matter in the effluent was not affected by HNQ. The HNQ promoted the production of FeO(OH) and up-regulated the proportion of Zoogloea (54.75% in the microbial community), indicating that Zoogloea sp. FY6 was dominant in the microbial community. In addition, HNQ influenced the metabolic pathways and improved the relative abundance of some genes involved in nitrogen metabolism and the iron redox cycle.
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