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1.
Food Chem ; 367: 130774, 2022 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-34390913

RESUMO

Gas-liquid microextraction technique (GLME) has been integrated with dispersive solid phase extraction to establish a one-step sample pretreatment approach for rapid analysis of multi-class pesticides in different plant-derived foods. A 50 µL of organic solvent plus 40 mg of PSA were required throughout the 5-minute pretreatment procedure. Good trueness (recoveries of 67.2 - 105.4%) and precision (RSD ≤ 18.9%) were demonstrated by the one-step GLME method, with MLOQs ranged from 0.001 to 0.011 mg kg-1. As high as 93.6% pesticides experienced low matrix effect through this method, and the overall matrix effects (ME%) were generally better or comparable to QuEChERS. This method successfully quantified 2-phenylphenol, quintozene, bifenthrin and permethrin in the range of 0.001 - 0.008 mg kg-1 in real food samples. The multiresidue analysis feature of GLME has been validated, which displays further potential for on-site determination of organic pollutants in order to safeguard food safety and human health.


Assuntos
Resíduos de Praguicidas , Praguicidas , Humanos , Resíduos de Praguicidas/análise , Praguicidas/análise , Extração em Fase Sólida , Solventes
2.
Bioresour Technol ; 343: 126111, 2021 Oct 11.
Artigo em Inglês | MEDLINE | ID: mdl-34648964

RESUMO

Dark fermentation process for simultaneous wastewater treatment and H2 production is gaining attention. This study aimed to use machine learning (ML) procedures to model and analyze H2 production from wastewater during dark fermentation. Different ML procedures were assessed based on the mean squared error (MSE) and determination coefficient (R2) to select the most robust models for modeling the process. The research showed that gradient boosting machine (GBM), support vector machine (SVM), random forest (RF) and AdaBoost were the most appropriate models, which were optimized by grid search and deeply analyzed by permutation variable importance (PVI) to identify the relative importance of process variables. All four models demonstrated promising performances in predicting H2 production with high R2 values (0.893, 0.885, 0.902 and 0.889) and small MSE values (0.015, 0.015, 0.016 and 0.015). Moreover, RF-PVI demonstrated that acetate, butyrate, acetate/butyrate, ethanol, Fe and Ni were of high importance in decreasing order.

3.
Artigo em Inglês | MEDLINE | ID: mdl-34467484

RESUMO

Due to their wide distribution and availability, plant leaves can be considered interesting candidates as biomonitoring substrates for the evaluation of atmospheric pollution. In addition, some species can also retain historical information, for example, related to environmental pollution, due to their leaf class age. In this study, the content of polycyclic aromatic hydrocarbons (PAHs) in Abies holophylla and Pinus tabuliformis needle samples in the function of their class age has been investigated to obtain information regarding the degradation constant for each PAH under investigation (α values ranging from 0.173 to 1.870) and to evaluate the possibility to correlate the presence of PAHs in needles with some important pollution environmental factors. Considering air pollutant variables registered in Jilin Province, interesting correlations (at 95% confidence level) have been found between coal consumption per year and anthracene contents in needles, while fluorene, phenanthrene, and anthracene results correlated with coal consumption. Furthermore, it has been demonstrated that the total PAH concentration in needles, for both species, increased with their age (from 804 to 3604 ng g-1 dry weight), showing a general tendency to accumulate these substances through years. PAH degradation rates increased instead with molecular complexity. This study could be considered a first trial to obtain historical environmental information by pine needles biomonitoring.

4.
Sci Total Environ ; 793: 148602, 2021 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-34351295

RESUMO

Vehicle emissions have a significantly negative impact on climate change, air quality and human health. Drivers of vehicles are the last major and often overlooked factor that determines vehicle performance. Eco-driving is a relatively low-cost and immediate measure to reduce fuel consumption and emissions significantly. This paper reports investigation of the effects of an on-board green-safety device on fuel consumption and emissions for both experienced and inexperienced drivers. A portable emissions measurement system (PEMS) was installed on a diesel light goods vehicle (LGV) to measure real-driving emissions (RDE), including total hydrocarbons (THC), CO CO2, NO, NO2 and particulate matter (PM). In addition, driving parameters (e.g. vehicle speed and acceleration) and environmental parameters (e.g. ambient temperature, humidity and pressure) were recorded in the experiments. The experimental results were evaluated using the Vehicle Specific Power (VSP) methodology to understand the effects of driving behavior on fuel consumption and emissions. The results indicated that driving behavior was improved for both experienced and inexperienced drivers after activation of the on-board green-safety device. In addition, the average time spent was shifted from higher to lower VSP modes by avoiding excessive speed, and aggressive accelerations and decelerations. For experienced drivers, the average fuel consumption and NO, NO2 and soot emissions were reduced by 5%, 56%, 39% and 35%, respectively, with the on-board green-safety device. For inexperienced drivers, the average reductions were 6%, 65%, 50% and 19%, respectively. Moreover, the long-term formed habits of experienced drivers are harder to be changed to accept the assistance of the green-safety device, whereas inexperienced drivers are likely to be more receptive to change and improve their driving behaviors.


Assuntos
Poluentes Atmosféricos , Poluição do Ar , Poluentes Atmosféricos/análise , Poluição do Ar/análise , Gasolina , Humanos , Material Particulado/análise , Equipamentos de Proteção , Emissões de Veículos/análise
5.
J Agric Food Chem ; 69(32): 9434-9442, 2021 Aug 18.
Artigo em Inglês | MEDLINE | ID: mdl-34374286

RESUMO

A rapid nanoconfined liquid phase filtration system (NLPF) based on solvent-confined carbon nanofibers/carbon fiber materials (CNFs/CFs) was proposed to effectively remove chlorinated pesticides from ginsenosides-containing ginseng extracts. A series of major parameters that may affect the separation performance of the CNFs-NLPF method were extensively investigated, including the water solubility of nanoconfined solvents, filtration rate, ethanol content of the ginseng extracts, and reusability of the material for repeated adsorption. The developed method showed a high removal efficiency of pesticides (85.5-97.5%), high retainment rate of ginsenosides (95.4-98.9%), and consistent reproducibility (RSD < 11.8%). Furthermore, the feasibility of the CNFs-NLPF technique to be scaled-up for industrial application was systematically explored by analyzing large-volume ginseng extract (1 L), which also verified its excellent modifiable characteristic. This filtration method exhibits promising potential as a practical tool for removing pesticide residues and other organic pollutants in food samples to assure food quality and safeguard human health.


Assuntos
Ginsenosídeos , Nanofibras , Panax , Praguicidas , Carbono , Cromatografia Líquida de Alta Pressão , Ginsenosídeos/análise , Humanos , Extratos Vegetais , Reprodutibilidade dos Testes
6.
Sci Total Environ ; 798: 149297, 2021 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-34332382

RESUMO

Eco-driving has attracted great attention as a cost-effective and immediate measure to reduce fuel consumption significantly. Understanding the impact of driver behaviour on real driving emissions (RDE) is of great importance for developing effective eco-driving devices and training programs. Therefore, this study was conducted to investigate the performance of different drivers using a portable emission measurement system. In total, 30 drivers, including 15 novice and 15 experienced drivers, were recruited to drive the same diesel vehicle on the same route, to minimise the effect of uncontrollable real-world factors on the performance evaluation. The results show that novice drivers are less skilled or more aggressive than experienced drivers in using the accelerator pedal, leading to higher vehicle and engine speeds. As a result, fuel consumption rates of novice drivers vary in a slightly greater range than those of experienced drivers, with a marginally higher (2%) mean fuel consumption. Regarding pollutant emissions, CO and THC emissions of all drivers are well below the standard limits, while NOx and PM emissions of some drivers significantly exceed the limits. Compared with experienced drivers, novice drivers produce 17% and 29% higher mean NOx and PM emissions, respectively. Overall, the experimental results reject the hypothesis that driver experience has significant impacts on fuel consumption performance. The real differences lie in the individual drivers, as the worst performing drivers have significantly higher fuel consumption rates than other drivers, for both novice and experienced drivers. The findings suggest that adopting eco-driving skills could deliver significant reductions in fuel consumption and emissions simultaneously for the worst performing drivers, regardless of driving experience.


Assuntos
Poluentes Atmosféricos , Condução de Veículo , Poluentes Ambientais , Poluentes Atmosféricos/análise , Gasolina , Equipamentos de Proteção , Emissões de Veículos/análise
7.
Sci Total Environ ; 797: 148940, 2021 Nov 25.
Artigo em Inglês | MEDLINE | ID: mdl-34293611

RESUMO

Despite a wealth of information on removal of the microplastics (MPs) in wastewater treatment plants (WWTPs), little attention has been paid to how wastewater treatment process affect the MP physicochemical and adsorption characteristics. In this study, changes in physicochemical property of three MPs, i.e. polyamide (PA), polyethylene (PE) and polystyrene (PS) through the wastewater pipeline, grit and biological aeration tanks were investigated. The results show that compared with virgin MPs, the treated MPs have higher specific surface area and O content, and lower C and H contents, and glass transition temperature, implying that the three treatments cause the chain scission and oxidation of the MPs. Cd adsorption capacities of the MPs are higher than the corresponding virgin MPs after sulfidation in the pipeline (SWPN) and biological treatment in aeration tank (BTAT). Pearson correlation analysis shows that the increase is mainly resulted from the enhancement of the O-containing groups on the MPs. However, Cd adsorption capacities of the MPs decrease after mechanical abrasion in grit tank (MAGT), corresponding to the decrease in carbonyl index. Two dimensional FTIR correlation spectroscopy demonstrates that the NH bond in the PA plays a more important role than CH bond in the adsorption of Cd, but only change of the CH bond is found in the PE and PS. The findings provide new insights into the effect of WWTPs on the MP aging and physicochemical characteristics.


Assuntos
Microplásticos , Poluentes Químicos da Água , Adsorção , Cádmio , Plásticos , Águas Residuárias , Poluentes Químicos da Água/análise
8.
Sci Total Environ ; 794: 148668, 2021 Nov 10.
Artigo em Inglês | MEDLINE | ID: mdl-34225154

RESUMO

Soil contamination is increasingly a global problem with serious implications for human health. Among different soil decontamination approaches, electrokinetic (EK) remediation is a relatively new technology for treating organic and inorganic contaminants in soil. This research aims to develop an enhanced EK treatment method incorporating a compost-based reactive filter media (RFM) with the advantages of low-cost and strong affinity for heavy metals and test and improve the treatment efficiency for multiple heavy metals in natural soil. A series of EK operations were performed to investigate the performance of EK-RFM under different operating conditions such as the electric current and voltage, processing time, and the amount of RFM. The electric current and treatment time demonstrated a significant positive impact on removing Zn, Cd and Mn ions while changing the amount of RFM had an insignificant impact on the efficiency of heavy metals removal. Overall, 51.6%-72.1% removal of Zn, Cd, and Mn was achieved at 30.00 mA of electric current and 14 days of treatment duration. The energy consumption of the EK process was 0.17 kWh kg-1. The soil organic matter adversely affected the mobilization and migration of heavy metals such as Cu and Pb during EK treatment. The results are valuable in optimizing the design of the EK-RFM system, which will extend its application to field-scale soil decontamination practices.


Assuntos
Recuperação e Remediação Ambiental , Metais Pesados , Poluentes do Solo , Humanos , Metais Pesados/análise , Solo , Poluentes do Solo/análise , Tecnologia
9.
J Environ Manage ; 296: 113274, 2021 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-34271355

RESUMO

Arsenic (As) is a heavy metal that causes widespread contamination and toxicity in the soil environment. This article reviewed the levels of As contamination in soils worldwide, and evaluated how soil properties (pH, clay mineral, organic matter, texture) and environmental conditions (ionic strength, anions, bacteria) affected the adsorption of As species on soils. The application of the adsorption isotherm models for estimating the adsorption capacities of As(III) and As(V) on soils was assessed. The results indicated that As concentrations in contaminated soil varying significantly from 1 mg/kg to 116,000 mg/kg, with the highest concentrations being reported in Mexico with mining being the dominating source. Regarding the controlling factors of As adsorption, soil pH, clay mineral and texture had demonstrated the most significant impacts. Both Langmuir and Freundlich isotherm models can be well fitted with As(III) and As(V) adsorption on soils. The Langmuir adsorption capacity varied in the range of 22-42400 mg/kg for As(V), which is greater than 45-8901 mg/kg for As(III). The research findings have enhanced our knowledge of As contamination in soil and its underlying controls, which are critical for the effective management and remediation of As-contaminated soil.


Assuntos
Arsênio , Metais Pesados , Poluentes do Solo , Adsorção , Arsênio/análise , Metais Pesados/análise , Solo , Poluentes do Solo/análise
10.
Sci Total Environ ; 791: 148303, 2021 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-34118676

RESUMO

Phthalic acid esters (PAEs) are one of the most widely used plasticizers and the well-studied environmental pollutants with endocrine disrupting properties. Investigation about PAEs in terrestrial ecosystem has been extensively conducted while the fate of PAEs in marine environment remains underexplored. In this study, a novel di-(2-ethylhexyl) phthalate (DEHP) degrading marine bacterial strain, Mycolicibacterium phocaicum RL-HY01, was isolated and characterized from intertidal sediments. Strain RL-HY01 could utilize a range of PAE plasticizers as sole carbon source for growth. The effects of different environmental factors on the degradation of PAEs were evaluated and the results indicated that strain RL-HY01 could efficiently degrade PAEs under a wide range of pH (5.0 to 9.0), temperature (20 °C to 40 °C) and salinity (below 10%). Specifically, when Tween-80 was added as solubilizing agent, strain RL-HY01 could rapidly degrade DEHP and achieve complete degradation of DEHP (50 mg/L) in 48 h. The kinetics of DEHP degradation by RL-HY01 were well fitted with the modified Gompertz model. The metabolic intermediates of DEHP by strain RL-HY01 were identified by ultra-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) analysis and then the metabolic pathway of DEHP was deduced. DEHP was transformed into di-ethyl phthalate (DEP) via ß-oxidation and then DEP was hydrolyzed into phthalic acid (PA) by de-esterification. PA was further transformed into gentisate via salicylic acid and further utilized for cell growth. Bioaugmentation of strain RL-HY01 with marine samples was performed to evaluate its application potential and the results suggested that strain RL-HY01 could accelerate the elimination of DEHP in marine samples. The results have advanced our understanding of the fate of PAEs in marine ecosystem and identified an efficient bioremediation strategy for PAEs-polluted marine sites.


Assuntos
Dietilexilftalato , Ácidos Ftálicos , Biodegradação Ambiental , Dibutilftalato , Ecossistema , Ésteres , Redes e Vias Metabólicas , Mycobacteriaceae , Espectrometria de Massas em Tandem
11.
J Environ Manage ; 294: 113024, 2021 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-34139645

RESUMO

This study reports landfill leachate treatment by the forward osmosis (FO) process using hydrogen peroxide (H2O2) for membrane cleaning. Although chemical cleaning is an effective method for fouling control, it could compromise membrane integrity. Thus, understanding the impact of chemical cleaning on the forward osmosis membrane is essential to improving the membrane performance and lifespan. Preliminary results revealed a flux recovery of 98% in the AL-FS mode (active layer facing feed solution) and 90% in the AL-DS (draw solution faces active layer) using 30% H2O2 solution diluted to 3% by pure water. The experimental work investigated the effects of chemical cleaning on the polyamide active and polysulfone support layers since the FO membrane could operate in both orientations. Results revealed that polysulfone support layer was more sensitive to H2O2 damage than the polyamide active at a neutral pH. The extended exposure of thin-film composite (TFC) FO membrane to H2O2 was investigated, and the active layer tolerated H2O2 for 72 h, and the support layer for only 40 h. Extended operation of the TFC FO membrane in the AL-FS based on a combination of physical (hydraulic flushing with DI water) and H2O2 was reported, and chemical cleaning with H2O2 could still recover 92% of the flux.


Assuntos
Poluentes Químicos da Água , Purificação da Água , Estudos de Viabilidade , Peróxido de Hidrogênio , Membranas Artificiais , Osmose
12.
J Hazard Mater ; 412: 125159, 2021 06 15.
Artigo em Inglês | MEDLINE | ID: mdl-33951855

RESUMO

Poly- and perfluoroalkyl substances (PFAS) are increasingly investigated due to their global occurrence and potential human health risk. The ban on PFOA and PFOS has led to the use of novel substitutes such as GenX, F-53B and OBS. This paper reviews the studies on the occurrence, transformation and remediation of major PFAS i.e. PFOA, PFNA, PFBA, PFOS, PFHxS, PFBS and the three substitutes in groundwater. The data indicated that PFOA, PFBA, PFOS and PFBS were present at high concentrations up to 21,200 ng L-1 while GenX and F-53B were found up to 30,000 ng L-1 and 0.18-0.59 ng L-1, respectively. PFAS in groundwater are from direct sources e.g. surface water and soil. PFAS remediation methods based on membrane, redox, sorption, electrochemical and photocatalysis are analyzed. Overall, photocatalysis is considered to be an ideal technology with low cost and high degradation efficacy for PFAS removal. Photocatalysis could be combined with electrochemical or membrane filtration to become more advantageous. GenX, F-53B and OBS in groundwater treatment by UV/sulfite system and electrochemical oxidation proved effective. The review identified gaps such as the immobilization and recycling of materials in groundwater treatment, and recommended visible light photocatalysis for future studies.

13.
Bioresour Technol ; 330: 124998, 2021 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-33757679

RESUMO

Renewable energy, water conservation, and environmental protection are the most important challenges today. Osmotic membrane bioreactor (OMBR) is an innovative process showing superior performance in bioenergy production, eliminating contaminants, and low fouling tendency. However, salinity build-up is the main drawback of this process. Identifying the microbial community can improve the process in bioenergy production and contaminant treatment. This review aims to study the recent progress and challenges of OMBRs in contaminant removal, microbial communities and bioenergy production. OMBRs are widely reported to remove over 80% of total organic carbon, PO43-, NH4+ and emerging contaminants from wastewater. The most important microbial phyla for both hydrogen and methane production in OMBR are Firmicutes, Proteobacteria and Bacteroidetes. Firmicutes' dominance in anaerobic processes is considerably increased from usually 20% at the beginning to 80% under stable condition. Overall, OMBR process has great potential to be applied for simultaneous bioenergy production and wastewater treatment.


Assuntos
Microbiota , Purificação da Água , Reatores Biológicos , Membranas Artificiais , Osmose , Águas Residuárias
14.
Environ Pollut ; 280: 116971, 2021 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-33774541

RESUMO

Urban street canyons formed by high-rise buildings restrict the dispersion of vehicle emissions, which pose severe health risks to the public by aggravating roadside air quality. However, this issue is often overlooked in city planning. This paper reviews the mechanisms controlling vehicle emission dispersion in urban street canyons and the strategies for managing roadside air pollution. Studies have shown that air pollution hotspots are not all attributed to heavy traffic and proper urban design can mitigate air pollution. The key factors include traffic conditions, canyon geometry, weather conditions and chemical reactions. Two categories of mitigation strategies are identified, namely traffic interventions and city planning. Popular traffic interventions for street canyons include low emission zones and congestion charges which can moderately improve roadside air quality. In comparison, city planning in terms of building geometry can significantly promote pollutant dispersion in street canyons. General design guidelines, such as lower canyon aspect ratio, alignment between streets and prevailing winds, non-uniform building heights and ground-level building porosity, may be encompassed in new development. Concurrently, in-street barriers are widely applicable to rectify the poor roadside air quality in existing street canyons. They are broadly classified into porous (e.g. trees and hedges) and solid (e.g. kerbside parked cars, noise fences and viaducts) barriers that utilize their aerodynamic advantages to ease roadside air pollution. Post-evaluations are needed to review these strategies by real-world field experiments and more detailed modelling in the practical perspective.


Assuntos
Poluentes Atmosféricos , Poluição do Ar , Poluentes Atmosféricos/análise , Poluição do Ar/análise , Poluição do Ar/prevenção & controle , Cidades , Modelos Teóricos , Árvores , Emissões de Veículos/análise , Vento
15.
Sci Total Environ ; 775: 145793, 2021 Jun 25.
Artigo em Inglês | MEDLINE | ID: mdl-33631597

RESUMO

Microplastics (MPs) pollution has become one of the most severe environmental concerns today. MPs persist in the environment and cause adverse effects in organisms. This review aims to present a state-of-the-art overview of MPs in the aquatic environment. Personal care products, synthetic clothing, air-blasting facilities and drilling fluids from gas-oil industries, raw plastic powders from plastic manufacturing industries, waste plastic products and wastewater treatment plants act as the major sources of MPs. For MPs analysis, pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS), Py-MS methods, Raman spectroscopy, and FT-IR spectroscopy are regarded as the most promising methods for MPs identification and quantification. Due to the large surface area to volume ratio, crystallinity, hydrophobicity and functional groups, MPs can interact with various contaminants such as heavy metals, antibiotics and persistent organic contaminants. Among different physical and biological treatment technologies, the MPs removal performance decreases as membrane bioreactor (> 99%) > activated sludge process (~98%) > rapid sand filtration (~97.1%) > dissolved air floatation (~95%) > electrocoagulation (> 90%) > constructed wetlands (88%). Chemical treatment methods such as coagulation, magnetic separations, Fenton, photo-Fenton and photocatalytic degradation also show moderate to high efficiency of MP removal. Hybrid treatment technologies show the highest removal efficacies of MPs. Finally, future research directions for MPs are elaborated.

16.
J Hazard Mater ; 402: 123891, 2021 01 15.
Artigo em Inglês | MEDLINE | ID: mdl-33254824

RESUMO

Electrokinetic (EK) remediation is a promising technology for soil decontamination, although basic pH in the soil close to cathode has constrained EK effectiveness due to heavy metal precipitation. This study aimed to enhance copper removal from kaolinite soil by integrating EK with compost (C) as recyclable reactive filter media (RFM) for the first time. Compost placed near the cathode served as an adsorbent to bind copper ions while buffering the advancement of the alkaline front in soil. The total copper removal rate increased from 1.03% in EK to 45.65% in EK-100%C under an electric potential of 10 V. Further experiments conducted by using biochar (BC) and compost/biochar (C + BC) mixture RFM at different ratios showed total Cu removal efficiency decreasing as EK-100%C > EK-(10%BC + 90%C) > EK-(20%BC + 80%C) > EK-(30%BC + 70%C) > EK. The application of a constant electric current of 20.00 mA further enhanced copper removal to 84.09% in EK-100%C although did not show significant enhancement in EK-(BC + C). The compost RFM was regenerated by acid extraction and then reused twice, achieving a total removal of 74.11%. The findings demonstrated compost as a promising and reusable RFM for the efficient removal of copper in contaminated soil.

17.
Environ Pollut ; 267: 115456, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-33254715

RESUMO

On-road remote sensing (RS) is a rapid, non-intrusive and economical tool to monitor and control the emissions of in-use vehicles, and currently is gaining popularity globally. However, a majority of studies used a single RS technique, which may bias the measurements since RS only captures a snapshot of vehicle emissions. This study aimed to use a unique dual RS technique to assess the characteristics of on-road vehicle emissions. The results show that instantaneous vehicle emissions are highly dynamic under real-world driving conditions. The two emission factors measured by the dual RS technique show little correlation, even under the same driving condition. This indicates that using the single RS technique may be insufficient to accurately represent the emission level of a vehicle based on one measurement. To increase the accuracy of identifying high-emitting vehicles, using the dual RS technique is essential. Despite little correlation, the dual RS technique measures the same average emission factors as the single RS technique does when a large number of measurements are available. Statistical analysis shows that both RS systems demonstrate the same Gamma distribution with ≥200 measurements, leading to converged mean emission factors for a given vehicle group. These findings point to the need for a minimum sample size of 200 RS measurements in order to generate reliable emission factors for on-road vehicles. In summary, this study suggests that using the single or dual RS technique will depend on the purpose of applications. Both techniques have the same accuracy in calculating average emission factors when sufficient measurements are available, while the dual RS technique is more accurate in identifying high-emitters based on one measurement only.


Assuntos
Poluentes Atmosféricos , Condução de Veículo , Monitoramento Ambiental , Veículos Automotores , Tecnologia de Sensoriamento Remoto , Projetos de Pesquisa , Tamanho da Amostra , Emissões de Veículos
18.
Bioresour Technol ; 316: 123967, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32777721

RESUMO

This study aims to analyze and model cathodic H2 recovery (rcat), coulombic efficiency (CE) with inputs of voltage, electrical conductivity (EC) and anode potential, and H2 production rate and total energy recovery with inputs of rcat and CE in a microbial electrolysis cell using artificial neural network (ANN) and adaptive network-based fuzzy inference system (ANFIS) procedures. Both ANN and ANFIS models demonstrated great goodness of fit for rcat, CE, H2 production rate and total energy recovery prediction with high R2 values. The sum square error values for rcat (0.0017), CE (0.0163), H2 production rate (0.1062) and total energy recovery (0.0136) in ANN models were slightly higher than those in ANFIS models at 0.0005, 0.0091, 0.1247 and 0.0148 respectively. Sensitivity analysis by ANN models demonstrated that voltage, EC, rcat and rcat were the most effective factors for rcat, CE, H2 production rate and total energy recovery, respectively.


Assuntos
Lógica Fuzzy , Hidrogênio , Eletrólise , Redes Neurais de Computação , Fenômenos Físicos
19.
Sci Total Environ ; 744: 140901, 2020 Nov 20.
Artigo em Inglês | MEDLINE | ID: mdl-32711320

RESUMO

This study presents systematic investigations to evaluate the performance, rejection rate, fouling, cleaning protocols and impact of physical and chemical cleaning strategies on the performance of commercial cellulose triacetate (CTA) membrane. The treatment of landfill leachate (LFL) solution was performed in the active layer facing feed solution and support layer facing the draw solution (AL-FS mode), and active layer facing the draw solution and support layer facing the feed solution (AL-DS mode). Compared to the AL-FS mode, a higher flux for AL-DS mode was achieved, but membrane fouling was more severe in the latter. In both membrane orientations, the rejection rate of the FO membrane to heavy ions and contaminants in the wastewater was between 93 and 99%. Physical and chemical cleaning strategies were investigated to recover the performance of the FO membrane and to study the impact of cleaning methods on the membrane rejection rate. Physical cleaning with hot water at 35 °C and osmotic backwashing with 1.5 M NaCl demonstrated excellent water flux recovery compared to chemical cleaning. In the chemical cleaning, an optimal concentration of 3% hydrogen peroxide was determined for 100% flux recovery of the fouled membrane. However, slight membrane damage was achieved at this concentration on the active layer side. Alkaline cleaning at pH 11 was more effective than acid cleaning at pH 4, although both protocols compromised the membrane rejection rate for some toxic ions. A comparison of the membrane long-term performance found that cleaning with osmotic backwashing and hot water were effective methods to restore water flux without comprising the membrane rejection rate. Overall, it was found that physical cleaning protocols are superior to chemical cleaning protocols for forward osmosis membrane fouled by landfill leachate wastewater.

20.
Sci Total Environ ; 740: 139868, 2020 Oct 20.
Artigo em Inglês | MEDLINE | ID: mdl-32559527

RESUMO

This study investigated real world in-use vehicle emissions using two regulatory techniques simultaneously, namely on-road remote sensing (RS) systems and air quality (AQ) monitoring stations, aiming to provide a full pollution profile from tailpipe to roadside and atmosphere. Two large AQ and RS datasets collected during 2012-2018 were analyzed. The effects of various emission control programmes on the trends of tailpipe emissions and air quality were evaluated. Correlations between tailpipe emissions and roadside and ambient air quality were also explored. The results showed a decreasing trend of NO2 at both roadside and ambient AQ stations from 2013 to 2016, which was attributed to the intensive implementation of a series of vehicle emissions control programmes. Although NO2 was decreasing, O3 was generally increasing for all AQ stations. AQ data showed that O3 had little correlation with either NO2 or NOx, but was mainly determined by NO2/NOx ratio. Roadside NO2/NOx ratio increased first and then decreased or stabilized after 2014, while ambient NO2/NOx ratio increased steadily. RS data showed that the overall NO decreased quickly during 2012-2015 and then decreased moderately after 2015. The decrease was mainly attributed to the effective NO reduction from LPG vehicles. However, diesel NO remained high and reduced relatively slowly during the study period. Gasoline vehicles were relatively clean compared with LPG and diesel vehicles. Finally, good correlations were demonstrated between NO measured by RS sites and NOx measured by roadside AQ stations, indicating that vehicle emissions were the major contributor to roadside NOx pollution. Ambient NOx emissions could be affected by various sources, leading to different correlation levels between RS and ambient AQ results.

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