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1.
Water Sci Technol ; 82(2): 281-291, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32941170

RESUMO

Biofilters based on earthworms-microorganisms represent, particularly in developing countries, an interesting alternative for domestic wastewater treatment due to their easy operation and low cost. However, there are several operational aspects that should be better understood in order to improve their performance. This paper studies the effect of using intermittent hydraulic loading rates to improve organic matter and nutrient removal from domestic wastewater using these biofilters. Three laboratory-scale columns, operating at a 2.5 m3 m-2day-1 hydraulic loading rate, were used. The B1-24 h, B2-8 h, B3-4 h column loading rates indicate that the columns were operated continuously for 24, 8 and 4 h, respectively. Each column (biomass biofilm/earthworms, redox potential, and head loss) and its corresponding operational performance parameters (TCOD, NH4+, NO3-, NO2-, TP) were monitored. The results showed that the B2-8 h intermittent hydraulic loading rate results in the best global performance, with 74%, 57%, and 20% average removal efficiencies for TCOD, nitrogen, and phosphorus, respectively. Moreover, it showed the best biomass growth (biofilm and earthworms), activity (as redox potential changes) and the lowest clogging effects (up to -1.0 cm). The intermittent operation influences the behavior of the earthworm-microorganism biofilters and offers the possibility of optimizing its global performance and achieving a resilient technology.


Assuntos
Oligoquetos , Águas Residuárias , Animais , Reatores Biológicos , Filtração , Nitrogênio/análise , Nutrientes , Fósforo , Eliminação de Resíduos Líquidos
6.
Sci Rep ; 10(1): 15665, 2020 09 24.
Artigo em Inglês | MEDLINE | ID: mdl-32973285

RESUMO

The COVID-19 pandemic triggered a surge in demand for facemasks to protect against disease transmission. In response to shortages, many public health authorities have recommended homemade masks as acceptable alternatives to surgical masks and N95 respirators. Although mask wearing is intended, in part, to protect others from exhaled, virus-containing particles, few studies have examined particle emission by mask-wearers into the surrounding air. Here, we measured outward emissions of micron-scale aerosol particles by healthy humans performing various expiratory activities while wearing different types of medical-grade or homemade masks. Both surgical masks and unvented KN95 respirators, even without fit-testing, reduce the outward particle emission rates by 90% and 74% on average during speaking and coughing, respectively, compared to wearing no mask, corroborating their effectiveness at reducing outward emission. These masks similarly decreased the outward particle emission of a coughing superemitter, who for unclear reasons emitted up to two orders of magnitude more expiratory particles via coughing than average. In contrast, shedding of non-expiratory micron-scale particulates from friable cellulosic fibers in homemade cotton-fabric masks confounded explicit determination of their efficacy at reducing expiratory particle emission. Audio analysis of the speech and coughing intensity confirmed that people speak more loudly, but do not cough more loudly, when wearing a mask. Further work is needed to establish the efficacy of cloth masks at blocking expiratory particles for speech and coughing at varied intensity and to assess whether virus-contaminated fabrics can generate aerosolized fomites, but the results strongly corroborate the efficacy of medical-grade masks and highlight the importance of regular washing of homemade masks.


Assuntos
Infecções por Coronavirus/prevenção & controle , Infecções por Coronavirus/transmissão , Máscaras , Pandemias/prevenção & controle , Pneumonia Viral/prevenção & controle , Pneumonia Viral/transmissão , Prevenção Primária/métodos , Dispositivos de Proteção Respiratória , Adolescente , Adulto , Aerossóis , Betacoronavirus , Tosse/virologia , Expiração , Feminino , Filtração/instrumentação , Humanos , Exposição por Inalação , Masculino , Pessoa de Meia-Idade , Prevenção Primária/instrumentação , Adulto Jovem
7.
Water Sci Technol ; 82(1): 131-143, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32910798

RESUMO

Higher standards in the European Water Framework Directive and national directive demand advanced wastewater treatment for removal of nutrients and organic micropollutants before the discharge into water bodies. Systematic investigations regarding relative dosage and filtration processes for removal of flocculated solids are currently lacking. In this study, the performance of technologies for advanced removal of total phosphorus down to <100 µg/L with pile cloth-filtration (CF) and membrane filtration was verified and synergy effects for the removal of other contaminants were identified. The results show that an over-stoichiometric addition of coagulants of >5 mol Me3+/mol sRP was necessary to achieve soluble reactive phosphorus (sRP) concentrations of <50 µg/L in the effluent. After the coupled process of tertiary phosphorus removal and solids removal, the soluble non-reactive phosphorus (sNRP) concentration regulates the lowest total phosphorus effluent concentration. sNRP is also partially, but not completely, removed by the use of coagulants. CF has proven to be an alternative technology for the removal of phosphorus and total suspended solids below the detection limit.


Assuntos
Fósforo , Eliminação de Resíduos Líquidos , Filtração , Floculação , Águas Residuárias
8.
Int J Hyg Environ Health ; 229: 113582, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32917368

RESUMO

The recent outbreak of the coronavirus disease (COVID-19) is causing a shortage of personal protective equipment (PPE) in different countries around the world. Because the coronavirus can transmit through droplets and aerosols, facemasks and N95 respirators that require complex certification, are urgently needed. Given the situation, the U.S. Centers for Disease Control and Prevention (CDC) recommends that "in settings where facemasks are not available, healthcare personnel might use homemade masks (e.g., bandana, scarf) for the care of patients with COVID-19 as a last resort." Although aerosols and droplets can be removed through the fibers of fabrics through a series of filtration mechanisms, their filtration performances have not been evaluated in detail. Moreover, there are a series of non-medical materials available on the market, such as household air filters, coffee filters, and different types of fabrics, which may be useful when facemasks and respirators are not available. In this study, we comprehensively evaluated the overall and size-dependent filtration performances of non-medical materials. The experiments were conducted under different face velocities to study its influence on size-dependent filtration performances. The flow resistance across these filter materials is measured as an indicator of the breathability of the materials. The results illustrate that multiple layers of household air filters are able to achieve similar filtration efficiencies compared to the N95 material without causing a significant increase in flow resistance. Considering that these air filters may shed micrometer fibers during the cutting and folding processes, it is recommended that these filters should be inserted in multiple layers of fabrics when manufacturing facemasks or respirators.


Assuntos
Betacoronavirus/isolamento & purificação , Infecções por Coronavirus/prevenção & controle , Filtração/métodos , Máscaras/normas , Pandemias/prevenção & controle , Pneumonia Viral/prevenção & controle , Dispositivos de Proteção Respiratória/normas , Aerossóis/análise , Humanos , Exposição por Inalação/prevenção & controle , Teste de Materiais , Têxteis/virologia , Estados Unidos
9.
Sci Adv ; 6(36)2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32917603

RESUMO

Mandates for mask use in public during the recent coronavirus disease 2019 (COVID-19) pandemic, worsened by global shortage of commercial supplies, have led to widespread use of homemade masks and mask alternatives. It is assumed that wearing such masks reduces the likelihood for an infected person to spread the disease, but many of these mask designs have not been tested in practice. We have demonstrated a simple optical measurement method to evaluate the efficacy of masks to reduce the transmission of respiratory droplets during regular speech. In proof-of-principle studies, we compared a variety of commonly available mask types and observed that some mask types approach the performance of standard surgical masks, while some mask alternatives, such as neck gaiters or bandanas, offer very little protection. Our measurement setup is inexpensive and can be built and operated by nonexperts, allowing for rapid evaluation of mask performance during speech, sneezing, or coughing.


Assuntos
Infecções por Coronavirus/prevenção & controle , Filtração/estatística & dados numéricos , Máscaras/estatística & dados numéricos , Pandemias/prevenção & controle , Pneumonia Viral/prevenção & controle , Betacoronavirus , Humanos , Imagem Óptica , Respiração , Fala
10.
PLoS One ; 15(9): e0239531, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32946526

RESUMO

The worldwide shortage of single-use N95 respirators and surgical masks due to the COVID-19 pandemic has forced many health care personnel to use their existing equipment for as long as possible. In many cases, workers cover respirators with available masks in an attempt to extend their effectiveness against the virus. Due to low mask supplies, many people instead are using face coverings improvised from common fabrics. Our goal was to determine what fabrics would be most effective in both practices. Under laboratory conditions, we examined the hydrophobicity of fabrics (cotton, polyester, silk), as measured by their resistance to the penetration of small and aerosolized water droplets, an important transmission avenue for the virus causing COVID-19. We also examined the breathability of these fabrics and their ability to maintain hydrophobicity despite undergoing repeated cleaning. Laboratory-based tests were conducted when fabrics were fashioned as an overlaying barrier for respirators and when constructed as face coverings. When used as material in these two situations, silk was more effective at impeding the penetration and absorption of droplets due to its greater hydrophobicity relative to other tested fabrics. We found that silk face coverings repelled droplets in spray tests as well as disposable single-use surgical masks, and silk face coverings have the added advantage over masks such that they can be sterilized for immediate reuse. We show that silk is a hydrophobic barrier to droplets, can be more breathable than other fabrics that trap humidity, and are re-useable via cleaning. We suggest that silk can serve as an effective material for making hydrophobic barriers that protect respirators, and silk can now be tested under clinical conditions to verify its efficacy for this function. Although respirators are still the most appropriate form of protection, silk face coverings possess properties that make them capable of repelling droplets.


Assuntos
Betacoronavirus , Infecções por Coronavirus/prevenção & controle , Máscaras/normas , Pandemias/prevenção & controle , Equipamento de Proteção Individual/normas , Pneumonia Viral/prevenção & controle , Seda/normas , Têxteis/normas , Filtração/métodos , Humanos , Interações Hidrofóbicas e Hidrofílicas , Equipamento de Proteção Individual/virologia , Dispositivos de Proteção Respiratória
11.
ACS Chem Neurosci ; 11(18): 2786-2788, 2020 09 16.
Artigo em Inglês | MEDLINE | ID: mdl-32870651

RESUMO

Herein, we propose the use of novel adsorbents, namely micelle clay complexes comprising the clay montmorillonite, coupled with activated carbon for effective eradication of neuropathogenic microbes such as SARS-CoV-2 and Naegleria fowleri from water supplies for ablution/nasal irrigation. These can be incorporated easily to water collection devices, i.e., taps and water bottles, in the domestic setting. These filters are low cost, easy to install, and ideal disinfection systems. Such strategies are particularly useful for communities who have lack of access to safe water supplies, rely heavily on water storage tanks, or lack adequate water sanitation facilities, especially in developing countries.


Assuntos
Infecções por Coronavirus/prevenção & controle , Filtração/métodos , Pandemias/prevenção & controle , Pneumonia Viral/prevenção & controle , Purificação da Água/métodos , Bentonita , Betacoronavirus , Infecções Protozoárias do Sistema Nervoso Central/prevenção & controle , Carvão Vegetal , Argila , Filtração/instrumentação , Humanos , Naegleria fowleri , Lavagem Nasal , Purificação da Água/instrumentação
12.
Water Sci Technol ; 82(3): 577-586, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32960801

RESUMO

In this study, the wet phase inversion method was used for fabrication of the flat sheet ultrafiltration (UF) membranes. Three different polymer types and two different wetting agents were used for the fabrication. The effect of polymer types and wetting agents were investigated on the structural and dye performance of casted membranes. Two different synthetic dyes, 100 ppm Setazol Red and 100 ppm Setazol Blue, were used for the performance test. Viscosity, contact angle, and molecular weight cut off (MWCO) of casted membranes were measured and an electro kinetic analyzer, dynamic mechanical analyzer (DMA) and scanning electron microscope (SEM) were used to determine the structural properties. While the highest water and dye permeability were obtained with PES-PEG membrane, PSf-plain membrane gave the highest removal efficiency for Setazol Red and Setazol Blue dyes, which was found to be 78.33% and 82.52%, respectively, in the conditions of neutral pH and ambient temperature. Addition of PVP and PEG wetting agents improved the structural properties and permeability of membranes, but the dye removal was decreased as against plain ones. As the retention of PEG and PVP-based PSf and PES membrane was calculated at an average of 50%, they could be used for dye retention separately or could be a candidate as a pretreatment membrane prior to nanofiltration or reverse osmosis to make their lifetime longer.


Assuntos
Ultrafiltração , Purificação da Água , Corantes , Filtração , Membranas Artificiais , Agentes Molhantes
13.
Ann Ig ; 32(5): 472-520, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32744582

RESUMO

INTRODUCTION: The health emergency caused by the spread of SARS-COV-2 virus has required the adoption of passive measures against contagion, such as social distancing. The use of filtering masks, of the different types available on the market, such as surgical and facial filtering masks (FFP1, FFP2 and FFP3), is also recommended. OBJECTIVES: The aim of this paper, within the Italian and European regulatory reference framework, is to suggest a rational application of existing methodologies that enable to know and assess the features and/or make a face mask intended to be used by the community. In addition to this, the study aims to provide a correct regulatory framework and useful information for a correct use and disposal of face masks. Another purpose is the assessment of the hygienic, sanitary and regulatory aspects related to the use and disposal of face masks. METHODS: The analysis of filtering masks is based on the review of scientific literature, the state of art of technology and the filtering means/materials available. Reference is made to filtering mechanisms and devices, the testing methods, the technical, manufacturing and performance features, and to the Italian and European regulatory reference framework. Reference is also made to the hygienic, sanitary and regulatory aspects related to the use and disposal of face masks. RESULTS: Surgical masks or, alternatively, filtering masks with a filtration efficiency between 90% and 95% for 3-µm particles, are the most practicable choice with minor contraindications. The reusable type of mask is conceptually superior compared to single-use masks, but cleaning procedures to be followed are quite complex and not always described in a clear way. CONCLUSIONS: The definition of rigorous and repeatable tests on mask filtration capacity, breathability, wearability, duration of use, regeneration, as well as safe disposal methods, are the main way to provide users with correct selection and use criteria. The results must be disclosed and disseminated quickly.


Assuntos
Betacoronavirus/isolamento & purificação , Infecções por Coronavirus/prevenção & controle , Filtração/instrumentação , Higiene/normas , Máscaras/normas , Pandemias/prevenção & controle , Pneumonia Viral/prevenção & controle , Têxteis/normas , Desenho de Equipamento , Europa (Continente) , França , Humanos , Higiene/legislação & jurisprudência , Itália , Máscaras/classificação , Eliminação de Resíduos de Serviços de Saúde/legislação & jurisprudência , Eliminação de Resíduos de Serviços de Saúde/métodos , Eliminação de Resíduos de Serviços de Saúde/normas
14.
J Environ Manage ; 271: 111005, 2020 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-32778290

RESUMO

The performance of a polyamide-based thin-film composite nanofiltration (NF) membrane (NF33) was investigated for the retention of atenolol, a pharmaceutical pollutant, from the single and binary aqueous solutions. The effect of pH, applied pressure, feed flux, initial atenolol (ATN) concentration, and different co-existing salts with varying concentrations were studied to test the performance of the membrane. The removal efficiency of ATN increased with increasing solution pH giving the highest retention (70.9 ± 3.1) at pH 9, which was slightly decreased with the increasing initial ATN concentration but increased with increasing applied pressure and feed flux. As per the uncharged solutes rejection concept, the average pore radius of NF membrane for slit-like and cylindrical pore geometries were, respectively 0.169 ± 0.003 and 0.264 ± 0.009 nm. The Spiegler-Kedem model could predict the performance of NF membrane by retaining ATN over the investigated range of feed flux. The calculated reflection coefficient (σ) was close to unity, demonstrating the convective transport. Addition of CaCl2 as a co-existing salt into the feed showed promoting effect on ATN retention, and its efficiency was lowered by the addition of NaCl and Na2SO4 salts. As per the cost analysis, the total annualized cost of treatment by the NF was found to be 0.53 $/m3.


Assuntos
Atenolol , Filtração , Membranas Artificiais , Rádio (Anatomia) , Água
15.
J Environ Manage ; 271: 111021, 2020 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-32778302

RESUMO

Clarifiers integrating radial cartridge filtration (RCF) are a combined unit operation variant of millennia-old sedimentation-filtration systems. Similarly, RCF is a primarily horizontal flow variant with flow orthogonal to gravity and a radial velocity gradient, in contrast to traditional deep-bed vertical filtration. These granular filters function at lower finite granular Reynolds numbers. A proposed computational fluid dynamics framework, implementing the Navier-Stokes equations, couples a pore-scale filter model with a macroscopic scale sedimentation-filtration model to create a tool examining non-Brownian particle separation. Validation is conducted using previous physical testing from a full-scale sedimentation-filtration system under steady flow and particulate loads. Model results illustrate a two-zone filtration structure with respect to particle diameter, similar to vertical filtration. The computational tool predicts particulate matter separation of 86.1% compared to 87.8% for physical testing. The physical-based computational framework does not need high-level calibration as compared to analytical, lumped, or empirical models; conferring direct extensibility to similar unit operation systems. The novel multi-scale tool simulates particulate matter fate in a modern re-incarnation of a sedimentation-filtration unit operation. The tool functions as an adjuvant that complements regulatory or certification testing. The tool can provide guidance for design or maintenance as well as system management with respect to particle fate in, and breakthrough from, granular filters in a combined unit operation.


Assuntos
Filtração , Hidrodinâmica , Modelos Teóricos , Tamanho da Partícula , Material Particulado
16.
J Environ Manage ; 274: 111145, 2020 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-32801108

RESUMO

This study investigates the use of electrically conductive granules as packing material in biotrickling filter (BTF) systems as to provide insights on the specific microbial abundance and functions during the treatment of xylene-containing waste gas. In addition, the effect of applied potential on attached biofilm on conductive granules during xylene degradation was briefly investigated. During stable operation period, the conductive granules packed BTF achieved reactor performance of no less than 80% with a maximum EC of 137.7 g/m3 h. Under applied potential of 1V, the BTF system showed deterioration of xylene removal by ranging from 21 to 76%, which also affected the distribution and relative abundance of the major microorganisms such as Xanthobacter, Acidovorax, Rhodococcus, Hydrogenophaga, Arthrobacter, Brevundimonas, Pseudoxanthomonas, Devosia, Shinella, Sphingobium, Dokdonella, Pseudomonas and Bosea. The acclimation of applied potential led to the enrichment of autotrophic bacteria and strains, which are correlated to improved nitrogen cycling. In general, applying electrical potential is feasible to shape the microbiological structure of biofilms to selectively adjust their biochemical functions.


Assuntos
Microbiota , Xilenos , Biodegradação Ambiental , Reatores Biológicos , Filtração
19.
Water Sci Technol ; 81(12): 2585-2598, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32857745

RESUMO

Bioleaching, a technologically and economically feasible technology, is considered as the high efficiency method to improve dewaterability in sewage sludge. The objective of this study was to investigate the effect of different sludge concentrations on bioleaching dewaterability and understand the mechanism of the effect of bioleaching on sludge dewaterability. Variation in pH, oxidation-reduction potential (ORP), capillary suction time (CST), specific resistance to filtration (SRF) and different fractions of extracellular polymeric substances (EPS) including slime EPS (S-EPS), loosely bound EPS (LB-EPS), and tightly bound EPS (TB-EPS) were determined. Different sludge concentrations (5, 10, 15, 20 and 30 g·L-1) were selected to investigate during bioleaching. Results indicated that sludge buffering capacity significantly inhibited bioleaching efficiency as sludge concentrations increased. Optimum enhancements in sludge dewaterability were observed during the 10 g·L-1 sludge concentration treatment, and reached a maximum when the pH was 2.11. The variation of different fractions of EPS revealed that the ratio of S-EPS/TB-EPS significantly affected sludge dewaterability. Principal component analysis and Pearson's correlation analysis both provided evidence that the higher TB-EPS followed by a very large reduction was positively correlated with sludge dewaterability. However, the increase of protein and DNA in S-EPS content was negatively correlated with sludge dewaterability.


Assuntos
Esgotos , Água , Matriz Extracelular de Substâncias Poliméricas , Filtração , Proteínas
20.
Bioresour Technol ; 316: 123930, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32763806

RESUMO

This research work proposes the scale-up evaluation in terms of biological and filtration performance from laboratory to pilot-scale of an anaerobic membrane bioreactor (AnMBR) co-digesting raw microalgae and primary sludge. Best operating conditions for this scale-up were energetically and economically assessed based on laboratory results. Economic balance showed 3% higher annual costs when operating a reactor at 100 d solids retention time (SRT) compared to 70 d SRT. Energetic balance showed a 5.5-fold increase in heat demand working at thermophilic temperature comparing to mesophilic. The AnMBR operating conditions were set at 70 d SRT and 35 °C. The pilot-scale and lab-scale co-digesters performed similarly in terms of biogas production and system stability. 154 mLbiogas·d-1·L-1reactor were produced at pilot-scale, corresponding to methane yield of 215 mLCH4·gCODinf-1. AnMBR filtration at both laboratory and pilot-scale showed stability working at permeate fluxes of 4.2-5.8 L·m-2·h-1.


Assuntos
Microalgas , Esgotos , Anaerobiose , Reatores Biológicos , Filtração , Metano
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