scholarly journals An Optimized Cr(VI)-Removal System Using Sn-based Reducing Adsorbents

Water ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 2477 ◽  
Author(s):  
George Papadopoulos ◽  
Theopoula Asimakidou ◽  
Dimitrios Karfaridis ◽  
Ioannis Kellartzis ◽  
George Vourlias ◽  
...  
Keyword(s):  
Drinking Water ◽  
High Efficiency ◽  
Flow Reactor ◽  
Synthesis Method ◽  
Free Water ◽  
Complete Removal ◽  
Polluted Water ◽  
Tin Chloride ◽  
Point Of Use ◽  
Test Operation

Despite significant risks to human health due to elevated Cr(VI) concentrations in drinking water, a selective adsorbent capable of purifying water before consumption is still not commercially available. This work introduces an integrated household water filtration setup, for point-of-use applications, loaded with a tin-based Cr(VI)-oriented adsorbent that was tested under various contact times, pH values and Cr(VI) concentrations. The adsorbent comprises a chloride-substituted stannous oxy-hydroxide with a structure resembling that of the mineral abhurite. It demonstrated high reducing capacity that triggered the formation of insoluble Cr(III) hydroxides and the complete removal of Cr(VI) in considerably high volumes of polluted water. Test operation of the filtration system verified its ability to produce Cr(VI)-free water in compliance with the impending drinking water regulation, even for extreme initial concentrations (1000 μg/L). Apart from its high efficiency, the potential of the studied material is enhanced by its minimal-cost synthesis method carried out in a continuous-flow reactor by tin chloride precipitation under acidic conditions.

Adapting the use of Fe3O4 nanoparticles in large-scale water treatment facilities

2014 ◽  
Vol 1708 ◽  
Author(s):  
K. Simeonidis ◽  
N. Andritsos ◽  
E. Kaprara ◽  
S. Mourdikoudis ◽  
M. Mitrakas
Keyword(s):  
Large Scale ◽  
Flow Reactor ◽  
Solid Phase ◽  
Complete Removal ◽  
Polluted Water ◽  
Batch Adsorption ◽  
Continuous Flow Reactor ◽  
Alkaline Conditions ◽  
Treatment Facilities ◽  
Co Precipitation

ABSTRACTMagnetite nanoparticles were produced by the chemical co-precipitation of iron sulfates at alkaline conditions and were tested as a Cr(VI) adsorbent from water. Batch adsorption experiments showed a high removal efficiency, which is maximized at pH values below 6. This behavior was also verified in a continuous flow reactor, where nanoparticles were in contact with the polluted water. In particular, using a particle concentration of 1 g/L in water containing 100 μg Cr(VI)/L, a contact time of at least 2 h was required to achieve complete removal of Cr(VI). The recovery of nanoparticles after their use was accomplished using their magnetic nature. Application of an external magnetic field at the sides of the tube in which the suspension was flowing was sufficient to completely collect the nanoparticles in the outflow of the contact reactor, thus, providing water free of Cr(VI) and a solid phase.

Lead removal from drinking water - development and validation of point-of-use treatment devices

2002 ◽  
Vol 2 (5-6) ◽  
pp. 209-216
Author(s):  
R. Sublet ◽  
A. Boireau ◽  
V.X. Yang ◽  
M.-O. Simonnot ◽  
C. Autugelle
Keyword(s):  
Drinking Water ◽  
Fixed Bed ◽  
Field Testing ◽  
Lead Removal ◽  
Ministry Of Health ◽  
Point Of Use ◽  
Taste And Odor ◽  
Wide Range ◽  
Lead Levels ◽  
Safety Considerations

Two lead removal water filters were developed to lower lead levels in drinking water below 10 μg.L-1 in order to meet the new regulation given by the European Directive 98-83, applicable in December 2013. An appropriate adsorbent was selected through a stringent research program among a wide range of media, and is composed of a synthetic zeolite and an activated carbon. Two prototypes were developed: the first is a faucet-mounted filter which contains a fixed bed of the adsorbent and a hollow fiber bundle, while the second is an under-sink cartridge made of a porous extruded block of carbon and adsorbent. Both are able to treat at least 1,000 litres of any water containing on average 100 to 150 μg Pb.L-1, by lowering the lead concentration below 10 μg.L-1. Once their safety considerations were addressed by an independent laboratory according to the French Ministry of Health recommendations, 20 prototypes were installed at consumers' taps in northeastern France. Their performance in terms of lead removal, HPC control and bad taste and odor reduction was followed for 6 months. This field testing program resulted in the validation of both prototypes which meet the new French Ministry of Health recommendations and assures that the filtered water is fully ED 98-83 compliant. Their commercialization will be launched first in France in middle 2002.

PTSA (pressure and thermal swing adsorption) method to remove trihalomethanes from drinking water

1997 ◽  
Vol 35 (7) ◽  
pp. 243-250 ◽  
Author(s):  
Shigekazu Nakano ◽  
Tomoko Fukuhara ◽  
Masami Hiasa
Keyword(s):  
Drinking Water ◽  
Residual Chlorine ◽  
Remarkable Difference ◽  
Adsorption Method ◽  
Heating And Cooling ◽  
Point Of Use ◽  
Thermal Swing Adsorption ◽  
Long Time ◽  
Musty Odor ◽  
Vacuum Heating

It has been widely recognized that trihalomethanes (THMs) in drinking water pose a risk to human health. THMs can be removed to a certain extent by the conventional point-of-use (POU) unit which is composed of activated carbon (AC) and microfilter. But it's life on THMs is relatively shorter than on residual chlorine or musty odor. To extent the life of AC adsorber, pressure and thermal swing adsorption (PTSA) was applied by preferential regeneration of chloroform. PTSA was effective to remove THMs, especially chloroform. Adsorption isotherms of chloroform at 25 and 70°C showed a remarkable difference so that thermal swing was considered effective. Chloroform was also desorbed by reducing pressure. By vacuum heating at 70°C, chloroform was almost desorbed from AC and reversible adsorption was considered possible. A prototype of POU unit with PTSA was proposed. Regeneration mode would consist of dewatering, vacuum heating and cooling (backwashing). The unit was maintained in bacteriostatic condition and could be used for a long time without changing an AC cartridge.

Must Desert Chukars (Alectoris chukar sinaica) Drink Water? Water Influx and Body Mass Changes in Response to Dietary Water Content

The Auk ◽  
1984 ◽  
Vol 101 (1) ◽  
pp. 47-52 ◽  
Author(s):  
A. Allan Degen ◽  
Berry Pinshow ◽  
Peter J. Shaw
Keyword(s):  
Drinking Water ◽  
Body Mass ◽  
Free Water ◽  
Energy Requirements ◽  
Fresh Matter ◽  
Alectoris Chukar ◽  
Water Influx ◽  
Green Vegetation ◽  
Body Mass Changes ◽  
Vegetation Water

Abstract The Chukar subspecies Alectoris chukar sinaica inhabits the Negev desert, which is characterized by hot, dry summers, and little winter rainfall. Vegetation is dry and dormant during the summer and autumn; green, succulent vegetation is available following winter rain. We studied whether or not and under what dietary conditions Chukars require drinking water. Four groups of Chukars in an outdoor aviary received either a dry ration + water, a dry ration + green vegetation, a dry ration + green vegetation + water, or green vegetation only. The birds offered only greens lost 15% of their body mass in the first 8 days and 2.9% over the next 6 days, while birds on the other three treatments maintained body mass. The birds receiving only greens had the highest total body water to body mass ratio and the highest water influx. We concluded that the Chukars receiving only green vegetation met their water requirements but not their maintenance energy requirements. Chukars fulfilled both their water and energy requirements on a dry ration + green vegetation (without drinking water); the green vegetation comprised approximately 60% of their total fresh matter intake, or 26% of their total dry matter intake. Our analysis suggests that wild desert Chukars do not require drinking water from early winter to late spring, when succulent forage is available, but probably need free water during summer and autumn, when the bulk of their diet is seeds.

Point of Use Household Drinking Water Filtration: A Practical, Effective Solution for Providing Sustained Access to Safe Drinking Water in the Developing World

2008 ◽  
Vol 42 (12) ◽  
pp. 4261-4267 ◽  
Author(s):  
Mark D. Sobsey ◽  
Christine E. Stauber ◽  
Lisa M. Casanova ◽  
Joseph M. Brown ◽  
Mark A. Elliott
Keyword(s):  
Drinking Water ◽  
Developing World ◽  
Water Filtration ◽  
Safe Drinking Water ◽  
Effective Solution ◽  
Point Of Use

scholarly journals Diarrhea prevalence in a randomized, controlled prospective trial of point-of-use water filters in homes and schools in the Dominican Republic

2021 ◽  
Vol 49 (1) ◽  
Author(s):  
Nathan Tintle ◽  
Kristin Van De Griend ◽  
Rachel Ulrich ◽  
Randall D. Wade ◽  
Tena M. Baar ◽  
...  
Keyword(s):  
Drinking Water ◽  
Water Samples ◽  
Controlled Trial ◽  
World Health ◽  
Dissolved Metals ◽  
Randomized Controlled ◽  
Point Of Use ◽  
Diarrhea Prevalence ◽  
Clean Drinking Water ◽  
Post Filter

Abstract Background Lack of sustainable access to clean drinking water continues to be an issue of paramount global importance, leading to millions of preventable deaths annually. Best practices for providing sustainable access to clean drinking water, however, remain unclear. Widespread installation of low-cost, in-home, point of use water filtration systems is a promising strategy. Methods We conducted a prospective, randomized, controlled trial whereby 16 villages were selected and randomly assigned to one of four treatment arms based on the installation location of Sawyer® PointONE™ filters (filter in both home and school; filter in home only; filter in school only; control group). Water samples and self-reported information on diarrhea were collected at multiple times throughout the study. Results Self-reported household prevalence of diarrhea decreased from 25.6 to 9.76% from installation to follow-up (at least 7 days, and up to 200 days post-filter installation). These declines were also observed in diarrhea with economic or educational consequences (diarrhea which led to medical treatment and/or missing school or work) with baseline prevalence of 9.64% declining to 1.57%. Decreases in diarrhea prevalence were observed across age groups. There was no evidence of a loss of efficacy of filters up to 200 days post-filter installation. Installation of filters in schools was not associated with decreases in diarrhea prevalence in school-aged children or family members. Unfiltered water samples both at schools and homes contained potential waterborne bacterial pathogens, dissolved heavy metals and metals associated with particulates. All dissolved metals were detected at levels below World Health Organization action guidelines. Conclusions This controlled trial provides strong evidence of the effectiveness of point-of-use, hollow fiber membrane filters at reducing diarrhea from bacterial sources up to 200 days post-installation when installed in homes. No statistically significant reduction in diarrhea was found when filters were installed in schools. Further research is needed in order to explore filter efficacy and utilization after 200 days post-installation. Trial registration ClinicalTrials.gov, NCT03972618. Registered 3 June 2019—retrospectively registered.

scholarly journals Methods, Protocols, Guidance and Standards for Performance Evaluation for Point-of-Use Water Treatment Technologies: History, Current Status, Future Needs and Directions

Water ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1094
Author(s):  
Emily S. Bailey ◽  
Nikki Beetsch ◽  
Douglas A. Wait ◽  
Hemali H. Oza ◽  
Nirmala Ronnie ◽  
...  
Keyword(s):  
Drinking Water ◽  
Water Treatment ◽  
Enteric Bacteria ◽  
Current Status ◽  
Household Water Treatment ◽  
Produce Water ◽  
Point Of Use ◽  
Treatment Technologies ◽  
Injury And Repair ◽  
Testing Protocols

It is estimated that 780 million people do not have access to improved drinking water sources and approximately 2 billion people use fecally contaminated drinking water. Effective point-of-use water treatment systems (POU) can provide water with sufficiently reduced concentrations of pathogenic enteric microorganisms to not pose significant health risks to consumers. Household water treatment (HWT) systems utilize various technologies that physically remove and/or inactivate pathogens. A limited number of governmental and other institutional entities have developed testing protocols to evaluate the performance of POU water treatment systems. Such testing protocols are essential to documenting effective performance because inferior and ineffective POU treatment technologies are thought to be in widespread use. This critical review examines specific practices, procedures and specification of widely available POU system evaluation protocols. Testing protocols should provide standardized and detailed instructions yet be sufficiently flexible to deal with different treatment technologies, test microbe priorities and choices, testing facility capabilities and public health needs. Appropriate infectivity or culture assays should be used to quantify test enteric bacteria, viruses and protozoan parasites, or other appropriate surrogates or substitutes for them, although processes based on physical removal can be tested by methods that detect microbes as particles. Recommendations include further research of stock microbe production and handling methods to consistently yield test microbes in a realistic state of aggregation and, in the case of bacteria, appropriately physiologically stressed. Bacterial quantification methods should address the phenomenon of bacterial injury and repair in order to maximally recover those that are culturable and potentially infectious. It is only with harmonized national and international testing protocols and performance targets that independent and unbiased testing can be done to assure consumers that POU treatment technologies are able to produce water of high microbial quality and low health risk.

A Determinant Elimination Method for Bottleneck Assignment and Generalized Assignment Problems

2012 ◽  
Vol 239-240 ◽  
pp. 1522-1527
Author(s):  
Wen Bo Wu ◽  
Yu Fu Jia ◽  
Hong Xing Sun
Keyword(s):  
Computational Complexity ◽  
Optimization Algorithm ◽  
Assignment Problem ◽  
Numerical Experiments ◽  
High Efficiency ◽  
Synthesis Method ◽  
Assignment Problems ◽  
Generalized Assignment ◽  
The Cost ◽  
Time And Space Complexity

The bottleneck assignment (BA) and the generalized assignment (GA) problems and their exact solutions are explored in this paper. Firstly, a determinant elimination (DE) method is proposed based on the discussion of the time and space complexity of the enumeration method for both BA and GA problems. The optimization algorithm to the pre-assignment problem is then discussed and the adjusting and transformation to the cost matrix is adopted to reduce the computational complexity of the DE method. Finally, a synthesis method for both BA and GA problems is presented. The numerical experiments are carried out and the results indicate that the proposed method is feasible and of high efficiency.

scholarly journals Faecal contamination of drinking water during collection and household storage: the need to extend protection to the point of use

2003 ◽  
Vol 1 (3) ◽  
pp. 109-115 ◽  
Author(s):  
Thomas F. Clasen ◽  
Andrew Bastable
Keyword(s):  
Drinking Water ◽  
Geometric Mean ◽  
Arithmetic Mean ◽  
Faecal Contamination ◽  
Household Level ◽  
Safe Water ◽  
Female Head ◽  
Point Of Use ◽  
Thermotolerant Coliforms ◽  
And Storage

Paired water samples were collected and analysed for thermotolerant coliforms (TTC) from 20 sources (17 developed or rehabilitated by Oxfam and 3 others) and from the stored household water supplies of 100 households (5 from each source) in 13 towns and villages in the Kailahun District of Sierra Leone. In addition, the female head of the 85 households drawing water from Oxfam improved sources was interviewed and information recorded on demographics, hygiene instruction and practices, sanitation facilities and water collection and storage practices. At the non-improved sources, the arithmetic mean TTC load was 407/100 ml at the point of distribution, rising to a mean count of 882/100 ml at the household level. Water from the improved sources met WHO guidelines, with no faecal contamination. At the household level, however, even this safe water was subject to frequent and extensive faecal contamination; 92.9% of stored household samples contained some level of TTC, 76.5% contained more than the 10 TTC per 100 ml threshold set by the Sphere Project for emergency conditions. The arithmetic mean TTC count for all samples from the sampled households was 244 TTC per 100 ml (geometric mean was 77). These results are consistent with other studies that demonstrate substantial levels of faecal contamination of even safe water during collection, storage and access in the home. They point to the need to extend drinking water quality beyond the point of distribution to the point of consumption. The options for such extended protection, including improved collection and storage methods and household-based water treatment, are discussed.

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