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1.
Sci Total Environ ; 865: 161289, 2023 Mar 20.
Artigo em Inglês | MEDLINE | ID: mdl-36587698

RESUMO

Recycling urban tail water for ecological base flow and landscape use offers a reliable solution for the problem of water resource shortage. But the long-term direct discharge of urban tail water can aggravate the eutrophication of surface water based on the present drainage standard of sewage plant. It is of great significance to develop low-cost and low-energy ecological technologies as transitional region between urban tail water and surface water. In this study, a pilot-scale ecological bed coupled with microbial electrochemical system (EB-MES) was established to treat urban tail water deeply. The system was operated for 96 days from June to September. Average TN removal efficiency in EB-MES under the condition of submerged plant coupled closed-circuit MES could reach 59.0 ± 16.6 %, which was 82.7 % and 38.1 % higher than that of open-circuit EB-MES and MES without plants, respectively. Microbial community structure testing indicated that multiple nitrogen metabolic mechanisms occurred in the system, including nitrification, electrode autotrophic denitrification, anammox, simultaneous nitrification and denitrification, and aerobic denitrification, which results in better denitrification efficiency under tail water. Our research provided a novel ecological technology with advantages of high-efficiency, low-energy and low-carbon and verified the feasibility in pilot scale for application in the advanced treatment of urban tail water.


Assuntos
Desnitrificação , Purificação da Água , Nitrificação , Esgotos/química , Purificação da Água/métodos , Processos Autotróficos , Nitrogênio/análise , Reatores Biológicos
2.
Environ Sci Technol ; 57(2): 1134-1143, 2023 Jan 17.
Artigo em Inglês | MEDLINE | ID: mdl-36602374

RESUMO

In situ synthesis of reactive oxygen species (ROS) on demand via oxygen activation (OA) is significant in biological, chemical, and environmental fields. Thus, the design of OA catalysts with adequate reactivity, durability, and selectivity is critical but challenging. Here, we report a CuxO@C core@shell photoelectrode prepared by encapsulating Cu/Cu2O/CuO into a carbon layer through anodic electropolymerization (electrophoresis-coupled self-assembly of carbon quantum dots). Theoretical prediction and experiments indicate that the carbon layer can effectively facilitate optical trapping and charge transfer, thus promoting photoelectric conversion and anti-photocorrosion performance of CuxO@C. The inner CuxO core acts as an electron reservoir and continuously injects electrons into the outer carbon layer shell, and the carbon atoms adjacent to oxygen-enriched functional groups (C-O-C and -COOH) in the electron-rich carbon layer work as the reactive sites to adsorb O2 and donate electrons to the antibonding orbital [lowest unoccupied molecular orbital (π*)] of dioxygen. Optimized adsorption and hydrogenation of the critical intermediates (*O2, *OOH, and *H2O2) and thermodynamically tunable O-O bond cleavage enable O2 being selectively reduced to the superoxide anion and hydroxyl radical via the mixed multielectron processes consisting of one- and three-electron pathways. Sulfamethoxazole, an emerging refractory organic contaminant widely present in the environment, can be effectively degraded (∼100% removal) in such an electrochemical platform, benefiting from the abundant ROS generated in situ. Our findings demonstrate an innovative strategy to develop highly efficient and selective OA catalysts for practical water purification.


Assuntos
Oxigênio , Purificação da Água , Espécies Reativas de Oxigênio/química , Peróxido de Hidrogênio/química , Carbono
3.
J Environ Manage ; 332: 117209, 2023 Jan 27.
Artigo em Inglês | MEDLINE | ID: mdl-36709713

RESUMO

A data-driven Bayesian Network (BN) model was developed for a large Australian drinking water treatment plant, whose raw water comes from a river into which a number of upstream dams outflow water and smaller tributaries flow. During wet weather events, the spatial distribution of rainfall has a crucial role on the incoming raw water quality, as runoff from specific sub-catchments usually causes significant turbidity and conductivity issues, as opposed to larger dam outflows which have typically better water quality. The BN relies on a conceptual model developed following expert consultation, as well as a combination of different types (e.g. water quality, flow, rainfall) and amount (e.g. high-frequency, daily, scarce depending on variable) of historical data. The validated model proved to have acceptable accuracy in predicting the probability of different incoming raw water quality ranges, and can be used to assess different scenarios (e.g. timing, flow) of dam water releases, for the purpose of achieving dilution of the tributary's poor-quality water and mitigate related drinking water treatment challenges.

4.
Environ Monit Assess ; 195(2): 321, 2023 Jan 23.
Artigo em Inglês | MEDLINE | ID: mdl-36689041

RESUMO

Traditional freshwater supplies have been over-abstracted in the current global problem of water scarcity. Through the analysis of complex experimental and real-time data, to improve the activity of water and wastewater treatment (WWT) systems, an artificial neural network (ANN), a computational model inspired by the human brain, and its variants were created. This review paper focuses on recent trends and advances in modeling and simulating different water and wastewater systems using ANN. This study uses ANN in watershed management, impurity removal from wastewater, and wastewater treatment plants. According to the literature review, ANN can predict nonlinear, linear, and complex systems with high accuracy and well control. Finally, the limitations and future scope of ANNs were discussed. ANN proved itself in the prediction of various water and WWT processes. Still, implementation has practical challenges, which include a lack of data availability, poorly built models, timely updates in developed models, and low repeatability. The use of a proper toolbox, faster computing power, and proper domain knowledge makes the practical implementation of ANN successful. As a result, ANN can build a solid foundation for attracting and motivating investigators to work in this region in the forthcoming.


Assuntos
Purificação da Água , Humanos , Água , Monitoramento Ambiental , Redes Neurais de Computação
5.
Water Sci Technol ; 87(1): 275-283, 2023 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-36640037

RESUMO

Electron beam (e-beam) treatment uses accelerated electrons to form oxidizing and reducing radicals when applied to water without the use of external chemicals. In this study, electron beam treatment was used to degrade 1,4-dioxane in several water matrices. Removal improved in the progressively cleaner water matrices and removals as high as 94% to 99% were observed at a dose of 2.3 kGy in secondary effluent. 1,4-dioxane removal was confirmed to be primarily through hydroxyl radical oxidation. The calculated electrical energy per order was found to be 0.53, 0.26, and 0.08 kWh/m3/order for secondary effluent (Avg. total organic carbon (TOC) 9.25 mg/L), granular activated carbon effluent (TOC 3.46 mg/L), and ultrapure water, respectively, with a 70% generation and transfer efficiency applied.


Assuntos
Poluentes Químicos da Água , Purificação da Água , Água , Elétrons , Dioxanos , Oxirredução
6.
J Environ Qual ; 2023 Jan 30.
Artigo em Inglês | MEDLINE | ID: mdl-36716263

RESUMO

In several low- and middle-income countries, such as India, the rapid construction of toilets to combat open defecation has not been matched with adequate wastewater treatment, resulting in extreme fecal contamination of the receiving environments. The sewage-receiving surface waterbodies, typically close to the residences, are a potential hotspot for disease transmission and antibiotic resistance. Water, soil, and sediment samples from seven wastewater receiving ponds (WRPs) were analyzed for water quality, chlorophyll-a, fecal contamination (yccT for Escherichia coli), 16S rRNA gene copies, and anthropogenic antibiotic resistance gene markers - sul1 and intI1. These WRPs were contrasted with two ponds that did not directly receive sewage. The water quality in the WRPs was comparable to raw sewage (BOD: 210-380 mg/L; COD: 350-630 mg/L; Total-N: 100-190 mg/L; and Total-P: 6-21 mg/L), and the relative levels of the DNA marker of E. coli were very high (yccT: 0.1 - ∼100% of total bacterial count) indicating extreme fecal contamination. The relative levels of sul1 and intI1 were 1 - 3 orders of magnitude higher in WRPs (sul1: 0.32 - 10% of total bacterial count; and intI1: 0.2 - 5% of total bacterial count) compared to the ponds that did not receive sewage directly. The relative levels of sul1 correlated with the DNA marker for the fecal indicator, E. coli (p -value<0.05; r = 0.50; Spearman's rank correlation), and poor water quality. This article is protected by copyright. All rights reserved.

7.
Environ Health Perspect ; 131(1): 16001, 2023 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-36715546

RESUMO

BACKGROUND: Centralized chlorination of urban piped water supplies has historically contributed to major reductions in waterborne illness. In locations without effective centralized water treatment, point-of-use (POU) chlorination for households is widely promoted to improve drinking water quality and health. Realizing these health benefits requires correct, consistent, and sustained product use, but real-world evaluations have often observed low levels of use. To our knowledge, no prior reviews exist on adoption of chlorine POU products. OBJECTIVES: Our objectives were to identify which indicators of adoption are most often used in chlorine POU studies, summarize levels of adoption observed, understand how adoption changes over time, and determine how adoption is affected by frequency of contact between participants and study staff. METHODS: We conducted a systematic review of household POU chlorination interventions or programs from 1990 through 2021 that reported a quantitative measure of adoption, were conducted in low- and middle-income countries, included data collection at households, and reported the intervention start date. RESULTS: We identified 36 studies of household drinking water chlorination products that met prespecified eligibility criteria and extracted data from 46 chlorine intervention groups with a variety of chlorine POU products and locations. There was no consensus definition of adoption of household water treatment; the most common indicator was the proportion of household stored water samples with free chlorine residual >0.1 or 0.2mg/L. Among studies that reported either free or total chlorine-confirmed adoption of chlorine POU products, use was highly variable (across all chlorine intervention groups at the last time point measured in each study; range: 1.5%-100%; sample size-weighted median=47%; unweighted median=58%). The median follow-up duration among intervention groups was 3 months. On average, adoption declined over time and was positively associated with frequency of contact between respondents and study staff. DISCUSSION: Although prior research has shown that POU chlorine products improve health when correctly and consistently used, a reliance on individual adoption for effective treatment is unlikely to lead to the widespread public health benefits historically associated with pressurized, centralized treatment of piped water supplies. https://doi.org/10.1289/EHP10839.


Assuntos
Água Potável , Purificação da Água , Humanos , Halogenação , Cloro , Qualidade da Água , Abastecimento de Água
8.
Molecules ; 28(1)2023 Jan 02.
Artigo em Inglês | MEDLINE | ID: mdl-36615584

RESUMO

The separation of oil/water emulsions has attracted considerable attention for decades due to the negative environmental impacts brought by wastewater. Among the various membranes investigated for separation, polyvinylidene fluoride (PVDF) membranes have shown significant advantages of ease of fabrication, high selectivity, and fair pore distribution. However, PVDF membranes are hydrophobic and suffer from severe fouling resulting in substantial flux decline. Meanwhile, the incorporation of wettable substrates during fabrication has significantly impacted the membrane performance by lowering the fouling propensity. Herein, we report the fabrication of an iron-containing porphyrin (hemin)-modified multi-walled carbon nanotube incorporated PVDF membrane (HA-MWCNT) to enhance fouling resistance and the effective separation of oil-in-water emulsions. The fabricated membrane was thoroughly investigated using the FTIR, SEM, EDX, AFM, and contact angle (CA) analysis. The HA-MWCNT membrane exhibited a water CA of 62° ± 0.5 and excellent pure water permeance of 300.5 L/m2h at 3.0 bar (400% increment), in contrast to the pristine PVDF, which recorded a CA of 82° ± 0.8 and water permeance of 59.9 L/m2h. The hydrophilic HA-MWCNT membrane further showed an excellent oil rejection of >99% in the transmembrane pressure range of 0.5-2.5 bar and a superb flux recovery ratio (FRR) of 82%. Meanwhile, the classical molecular dynamics (MD) simulations revealed that the HA-MWCNT membrane had greater solvent-accessible pores, which enhanced water permeance while blocking the hydrocarbons. The incorporation of the hemin-modified MWCNT is thus an excellent strategy and could be adopted in the design of advanced membranes for oil/water separation.


Assuntos
Nanotubos de Carbono , Purificação da Água , Emulsões , Hemina , Membranas Artificiais , Purificação da Água/métodos
9.
Langmuir ; 39(2): 899-908, 2023 Jan 17.
Artigo em Inglês | MEDLINE | ID: mdl-36606755

RESUMO

In this work, the gelation ability of a series of novel pyridine-based glucose tailored gelators (DPHAEN, DPHABN, and DPHAHN) with a flexible alkyl chain has been examined in binary solvent mixtures using a number of techniques, for example, UV spectroscopy, FT-IR spectroscopy, NMR spectroscopy, rheology measurement, SEM, XRD, and computational study. Proposed herein is an environment-friendly method to realize toxic dye separation and oil/water separation. It has been found that gels in a selective binary solvent mixture are efficient reusable absorbers of toxic dye molecules. A new gravitational force-driven, simple one-step, toxic dye removal and oil-water separation method is presented for sustainable filtration of waste water and simultaneous collection of oil. The gel column also showed high stability and reusability over repeated use and can be easily scaled for efficient clean-up of a large number of toxic dyes and oil spills present in water. Studies also exposed that the gel column can simultaneously separate dye molecules and mineral oils from water. This simple, green, and efficient method overcomes a nontrivial hurdle for environmentally safe separation of toxic dyes as well as oil/water mixtures and offers insights into the design of advanced materials for practical oil/water separation.


Assuntos
Poluição por Petróleo , Purificação da Água , Poluição por Petróleo/análise , Açúcares , Óleos/química , Espectroscopia de Infravermelho com Transformada de Fourier , Purificação da Água/métodos , Solventes/química , Géis/química , Corantes
10.
Sci Total Environ ; 866: 161339, 2023 Jan 02.
Artigo em Inglês | MEDLINE | ID: mdl-36603611

RESUMO

The climate change and increasing anthropogenic pressures are expected to limit the availability of water resources. Hence, active measures must be planned in vulnerable regions to ensure a sustainable water supply and minimize environmental impacts. A pilot test was carried out in the Llobregat River (NE Spain) aiming to provide a useful procedure to cope with severe droughts through indirect water reuse. Reclaimed water was used to restore the minimum flow of the lower Llobregat River, ensuring a suitable water supply downstream for Barcelona. A monitoring was performed to assess chemical and microbiological threats throughout the water treatment train, the river and the final drinking water, including 376 micropollutants and common microbiological indicators. The effects of water disinfection were studied by chlorinating reclaimed water prior to its discharge into the river. Data showed that 10 micropollutants (bromodichloromethane, dibromochloromethane, chloroform, EDDP, diclofenac, iopamidol, ioprimid, lamotrigine, ofloxacin and valsartan) posed a potential risk to aquatic life, whereas one solvent (1,4-dioxane) could affect human health. The chlorination of reclaimed water mitigated the occurrence of pharmaceuticals but, conversely, the concentration of halogenated disinfection by-products increased. From a microbiological perspective, the microbial load decreased along wastewater treatments and, later, along drinking water treatment, ultimately reaching undetectable values in final potable water. Non-chlorinated reclaimed water showed a lower log reduction of E. coli and coliphages than chlorinated water. However, the effect of disinfection vanished once reclaimed water was discharged into the river, as the basal concentration of microorganisms in the Llobregat River was comparable to that of non-chlorinated reclaimed water. Overall, our study indicates that indirect water reuse can be a valid alternative source of drinking water in densely populated areas such as Barcelona (Catalonia - NE Spain). A suitable monitoring procedure is presented to assess the related risks to human health and the aquatic ecosystem.

11.
Water Res ; 230: 119543, 2023 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-36628868

RESUMO

The applicability of chemical actinometry to characterize the fluence in UV reactors with reflections, non-parallel light, and variable water transmittance is limited due to the unknown effective path length or hydraulic shortcuts within the reactor. In this study, the effects of reflection and transmittance on actinometry were examined and a new, optimized and easy method for determining fluence was developed. KI/KIO3 and uridine actinometry experiments were carried out under controlled conditions using a collimated beam apparatus and a completely mixed batch reactor with or without diffuse reflection and compared to biodosimetry results. Whereas optically opaque actinometers such as KI/KIO3 are not directly capable of predicting the fluence of reflecting reactors, the results of uridine actinometry are influenced by reflection and transmission. To precisely predict the fluence rate in UV reactors with uridine, knowledge about the effective optical path length of the light is needed. Here, an existing method to mathematically calculate the optical path length was adopted and optimized for uridine actinometry. Results for average fluence were validated by biodosimetry using MS2 phages under different degrees of reflection and transmission. It could be shown that by modifying the bottom of the reactor with diffusely reflecting polytetrafluoroethylene foil, the fluence rate was increased by a factor of approximately 2.6 and the path length by factor of 2.4. When only half of the bottom was covered with reflective foil, fluence rate increased by a factor of 1.8 and path length by 1.8. Although this new approach cannot replace biodosimetry, to predict the fluence distribution received by microorganisms, it can provide means to characterize more complex reactor designs, validate results of advanced reactor modeling, and quantify fluence for non-parallel irradiation and reflective light, especially for the application of high fluence (e.g., advanced oxidation processes), where biodosimetry may be too sensitive. Further, comparing the fluence obtained with actinometry to the results of biodosimetry might qualitatively indicate hydraulic short cuts or unideal fluence distributions for flow-through reactors.


Assuntos
Raios Ultravioleta , Purificação da Água , Desinfecção/métodos , Purificação da Água/métodos , Levivirus
12.
Water Res ; 230: 119383, 2023 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-36630853

RESUMO

Coliphage have been suggested as an alternative to fecal indicator bacteria for assessing recreational beach water quality, but it is unclear how frequently and at what types of beaches coliphage produces a different management outcome. Here we conducted side-by-side sampling of male-specific and somatic coliphage by the new EPA dead-end hollow fiber ultrafiltration (D-HFUF-SAL) method and Enterococcus at southern California beaches over two years. When samples were combined for all beach sites, somatic and male-specific coliphage both correlated with Enterococcus. When examined categorically, Enterococcus would have resulted in approximately two times the number of health advisories as somatic coliphage and four times that of male-specific coliphage,using recently proposed thresholds of 60 PFU/100 mL for somatic and 30 PFU/100 mL for male-specific coliphage. Overall, only 12% of total exceedances would have been for coliphage alone. Somatic coliphage exceedances that occurred in the absence of an Enterococcus exceedance were limited to a single site during south swell events, when this beach is known to be affected by nearby minimally treated sewage. Thus, somatic coliphage provided additional valuable health protection information, but may be more appropriate as a supplement to FIB measurements rather than as replacement because: (a) EPA-approved PCR methods for Enterococcus allow a more rapid response, (b) coliphage is more challenging owing to its greater sampling volume and laboratory time requirements, and (c) Enterococcus' long data history has yielded predictive management models that would need to be recreated for coliphage.


Assuntos
Enterococcus , Qualidade da Água , Masculino , Humanos , Praias , California , Colífagos , Fezes/microbiologia , Microbiologia da Água , Monitoramento Ambiental/métodos
13.
Water Res ; 230: 119581, 2023 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-36638732

RESUMO

We developed and studied one of the first high-flow UV-LED water disinfection reactors applicable to point-of-entry (POE) water disinfection. A multiphysics computational model was created to predict the performance of UV reactor design concepts by modeling the synergic effect of radiation, hydrodynamics, and the inactivation kinetics of microorganisms. The geometrical optics that describe light propagation in terms of rays were employed to model the radiation profile of multiple UV-LEDs with optical components in complex reactor geometries, the first account of such an approach. The computational solution of the mass, momentum, and species equations was applied to model the hydrodynamics and kinetics. We designed a reactor through a detailed computational study of the optical and hydrodynamic performance of various design strategies. Highly efficient UV fluence distribution in the reactor was achieved by creating nearly collimated UV radiation beams across the reactor and managing the hydrodynamics using a flow distributor. We fabricated a prototype of the optimized reactor design for experimental studies. Biodosimetry tests were conducted for various flow rates and UV transmittances (UVTs), and the experimental results were compared with the model predictions. The design, which employed 14 UV-LEDs assembled over custom-made optical modules, resulted in a reduction equivalent dose (RED) of 65 mJ/cm2 at a flow rate of 20 liters per minute (LPM) while consuming about 50 W energy. This reactor design required only 0.05 W radiant power per LPM flow rate to achieve an NSF Class A UV dose equivalent of 40 mJ/cm2. The findings of this study provide insights into UV-LED reactor development strategies as well as the creation and application of reactor virtual prototyping tools for designing and optimizing highly efficient UV-LED reactors.


Assuntos
Purificação da Água , Purificação da Água/métodos , Hidrodinâmica , Cinética , Raios Ultravioleta , Desinfecção/métodos
14.
Water Res ; 230: 119577, 2023 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-36638735

RESUMO

Progress in heterogeneous advanced oxidation processes (AOPs) is hampered by several issues including mass transfer limitation, limited diffusion of short-lived reactive oxygen species (ROS), aggregation of nanocatalysts, and loss of nanocatalysts to treated water. These issues have been addressed in recent studies by executing the heterogeneous AOPs in confinement, especially in the nanopores of catalytic membranes. Under nanoconfinement (preferably at the length of less than 25 nm), the oxidant-nanocatalyst interaction, ROS-micropollutant interaction and diffusion of ROS have been observed to significantly improve, which results in enhanced ROS yield and mass transfer, improved reaction kinetics and reduced matrix effect as compared to conventional heterogenous AOP configuration. Given the significance of nanoconfinement effect, this study presents a critical review of the current status of membrane-based nanoconfined heterogeneous catalysis system for the first time. A succinct overview of the nanoconfinement concept in the context of membrane-based nanofluidic platforms is provided to elucidate the theoretical and experimental findings related to reaction kinetics, reaction mechanisms and molecule transport in membrane-based nanoconfined AOPs vs. conventional AOPs. In addition, strategies to construct membrane-based nanoconfined catalytic systems are explained along with conflicting arguments/opinions, which provides critical information on the viability of these strategies and future research directions. To show the desirability and applicability of membrane-based nanoconfined catalysis systems, performance governing factors including operating conditions and water matrix effect are particularly focused. Finally, this review presents a systematic account of the opportunities and technological constraints in the development of membrane-based nanoconfined catalytic platform to realize effective micropollutant elimination in water treatment.


Assuntos
Poluentes Químicos da Água , Purificação da Água , Espécies Reativas de Oxigênio , Purificação da Água/métodos , Oxirredução , Catálise
15.
J Water Health ; 21(1): 109-124, 2023 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-36705501

RESUMO

This study investigated the sources and microbiological quality of domestic water used by rural communities of Speightstown, Barbados; Carriacou, Grenada; and Nariva, Trinidad. The primary water source was harvested rainwater in Carriacou, and the public water supply for Nariva and Speightstown. Secondary water supplies of the communities came from untreated sources including rainwater, wells, boreholes and springs. E. coli was detected at higher frequencies in water from Carriacou (41.3%) and Nariva (47.4%) than Speightstown (3.6%). Generally, more untreated samples of rainwater (44.6%) and surface/ground water (58.3%) were E. coli positive than treated water obtained from the public supply (9.9%). These findings demonstrate the increased risk to residents in rural communities of the Caribbean who utilize untreated rainwater and environmental sources such as springs and wells. These results demonstrate the usefulness of traditional methods such as the compartment bag test in determining the microbiological quality of domestic water in resource-challenged rural communities of the Caribbean.


Assuntos
Água Subterrânea , População Rural , Humanos , Escherichia coli , Abastecimento de Água , Região do Caribe , Microbiologia da Água , Qualidade da Água
16.
Environ Monit Assess ; 195(2): 341, 2023 Jan 28.
Artigo em Inglês | MEDLINE | ID: mdl-36708453

RESUMO

Previous research indicates that the water distribution system used has a significant impact on the microbial quality of tap water sampled in First Nations reserves in Canada. This study tested tap water from homes in three First Nations reserves to compare the concentrations of four trihalomethanes and related water quality parameters between homes receiving piped water from a water treatment plant (WTP) versus homes equipped with cisterns that are filled by a water truck. Of all the samples collected across time from household taps, 75% of piped samples and 70% of cistern samples had TTHM concentrations exceeding Health Canada's maximum acceptable concentration (MAC) of 100 µg L-1 total trihalomethanes (TTHMs) in treated water. In all communities and across sampling times, trichloromethane (CHCl3) was the dominant trihalomethane (42-96%) followed by bromodichloromethane (CHBrCl2) (3-37%) and dibromochloromethane (CHClBr2) (1-18%). Tribromomethane (CHBr3) always accounted for < 5% of TTHMs. Within each of the three First Nations reserves, the water distribution system had no significant effect on TTHM concentration at the household level. Sampling month had a significant effect on TTHM concentration due to temporal changes in dissolved organic carbon of the source water. Results suggest that families in the studied First Nations reserves receive drinking water with high TTHM concentrations and that improvements to the water treatment plant might be the most effective way to minimize trihalomethane formation.


Assuntos
Água Potável , Poluentes Químicos da Água , Purificação da Água , Humanos , Abastecimento de Água , Manitoba , Monitoramento Ambiental , Purificação da Água/métodos , Trialometanos/análise , Canadá , Poluentes Químicos da Água/análise
17.
Artigo em Inglês | MEDLINE | ID: mdl-36673812

RESUMO

Hepatitis A is a common form of viral hepatitis. It is usually transmitted through the ingestion of contaminated food and water. This systematic review was carried out to summarise the overall prevalence of Hepatitis A virus (HAV) in different water matrices: untreated and treated wastewater, surface water, groundwater, drinking water, and others (e.g., irrigation water and floodwater). The literature search was performed in four databases: PubMed, Web of Science, Global Index Medicus, and Excerpta Medica Database. Heterogeneity (I2) was assessed using the χ2 test on the Cochran Q statistic and H parameters. A total of 200 prevalence data from 144 articles were included in this meta-analysis. The overall prevalence of HAV in water matrices was 16.7% (95% CI: 13.4-20.3). The prevalence for individual matrix was as follows: 31.4% (95% CI: 23.0-40.4) untreated wastewater, 18.0% (95% CI: 9.5-28.2) treated wastewater, 15.0% (95% CI: 10.1-20.5) surface water, 2.3% (95% CI: 0.1-6.0) in groundwater, 0.3% (95% CI: 0.0-1.7) in drinking water, and 8.5% (95% CI: 3.1-15.6) in other matrices. The prevalence was higher in low-income economies (29.0%). Africa and Eastern Mediterranean were the regions with higher HAV prevalence values. This study showed a high heterogeneity (I2 > 75%) with a significant publication bias (p value Egger test < 0.001). The results of this review suggest that water matrices could be an important route of HAV transmission even in industrialized countries, despite the lower prevalence compared to less industrialized countries, and the availability of advanced water management systems. More effective water/wastewater treatment strategies are needed in developing countries to limit the environmental circulation of HAV.


Assuntos
Água Potável , Vírus da Hepatite A , Hepatite A , Hepatite Viral Humana , Humanos , Hepatite A/epidemiologia , Prevalência
18.
Artigo em Inglês | MEDLINE | ID: mdl-36674141

RESUMO

Most conventional methods to remove heavy metals from water are efficient for high concentrations, but they are expensive, produce secondary pollution, and cannot remove low concentrations. This paper proposes a biological system to remove Cr(VI) from aqueous solutions; the biofilter is composed of a native Pseudomonas koreensis immobilized in calcium alginate beads. Lab experiments were conducted in batch reactors, considering different operating conditions: Cr(VI) concentration, temperature, pH, and time. At 30 °C and a pH of 6.6, the immobilized bacteria achieved their optimal adsorption capacity. In the chromium adsorption system, saturation was reached at 30 h with a qmax = 625 mg g-1. By adjusting the experimental data to the Langmuir and Freundlich models, it is suggested that P. koreensis forms a biofilm with a homogeneous surface where Cr(VI) is adsorbed and that the bacteria also incorporates the metal in its metabolism, leading to a multilayer adsorption. On the other hand, using Fourier transform infrared spectroscopy, it was inferred that the functional groups involved in the adsorption process were O-H and C=O, which are a part of the P. koreensis cell wall.


Assuntos
Poluentes Químicos da Água , Purificação da Água , Água , Adsorção , Alginatos/química , Poluentes Químicos da Água/análise , Cromo/análise , Purificação da Água/métodos , Concentração de Íons de Hidrogênio , Cinética , Espectroscopia de Infravermelho com Transformada de Fourier
19.
Int J Mol Sci ; 24(2)2023 Jan 09.
Artigo em Inglês | MEDLINE | ID: mdl-36674812

RESUMO

The World Health Organization (WHO) reports that two billion people worldwide lack access to safely managed water sources, including 1.2 billion who already have access to improved water sources. In many countries, household point-of-use (POU) water-treatment options are used to remove or deactivate microorganisms in water, but not all POU technologies meet WHO performance requirements to achieve safe drinking water. To improve the effectiveness of POU technologies, the use of multiple treatment barriers should be used as a way to increase overall treatment performance. The focus of this research is to evaluate multiple barrier treatment using chitosan, an organic coagulant-flocculant, to improve microbial and turbidity reductions in combination with sand filtration. Bench-scale intermittently operated sand filters with 16 cm layers of sands of two different grain sizes representing slow and rapid sand filters were dosed daily over 57 days with microbially spiked surface water volumes corresponding to household use. E. coli bacteria and MS2 coliphage virus reductions were quantified biweekly (N = 17) using culture methods. Bacteria and virus removals were significantly improved over sand filtration without chitosan pretreatment (Wilcoxon Rank-Sum, p < 0.05). When water was pretreated at an optimal chitosan dose of 10 mg/L followed by sand filtration, log10 reductions in bacteria and viruses met the two-star WHO performance level of effectiveness. Microbial and turbidity reductions generally improved over the filter operating period but showed no trends with filtration rates.


Assuntos
Quitosana , Água Potável , Vírus , Purificação da Água , Humanos , Escherichia coli , Dióxido de Silício , Purificação da Água/métodos , Bactérias
20.
Int J Mol Sci ; 24(2)2023 Jan 11.
Artigo em Inglês | MEDLINE | ID: mdl-36674925

RESUMO

Capacitive deionization (CDI) is a promising and cost-effective technology that is currently being widely explored for removing dissolved ions from saline water. This research developed materials based on activated carbon (AC) materials modified with zinc oxide (ZnO) nanorods and used them as high-performance CDI electrodes for water desalination. The as-prepared electrodes were characterized by cyclic voltammetry, and their physical properties were studied through SEM and XRD. ZnO-coated AC electrodes revealed a better specific absorption capacity (SAC) and an average salt adsorption rate (ASAR) compared to pristine AC, specifically with values of 123.66 mg/g and 5.06 mg/g/min, respectively. The desalination process was conducted using a 0.4 M sodium chloride (NaCl) solution with flow rates from 45 mL/min to 105 mL/min under an applied potential of 1.2 V. Furthermore, the energy efficiency of the desalination process, the specific energy consumption (SEC), and the maximum and minimum of the effluent solution concentration were quantified using thermodynamic energy efficiency (TEE). Finally, this work suggested that AC/ZnO material has the potential to be utilized as a CDI electrode for the desalination of saline water.


Assuntos
Purificação da Água , Óxido de Zinco , Carvão Vegetal , Cloreto de Sódio , Águas Salinas , Eletrodos
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