scholarly journals Assessing point-of-use ultraviolet disinfection for safe water in urban developing communities

2014 ◽  
Vol 12 (4) ◽  
pp. 663-669 ◽  
Author(s):  
Christina K. Barstow ◽  
Aaron D. Dotson ◽  
Karl G. Linden
Keyword(s):  
Pathogenic Bacteria ◽  
Flow Reactor ◽  
Low Cost ◽  
Plug Flow ◽  
Field Testing ◽  
Low Flow ◽  
Health Concern ◽  
Log Reduction ◽  
Point Of Use ◽  
Developing Communities

Residents of urban developing communities often have a tap in their home providing treated and sometimes filtered water but its microbial quality cannot be guaranteed. Point-of-use (POU) disinfection systems can provide safe drinking water to the millions who lack access to clean water in urban communities. While many POU systems exist, there are several concerns that can lead to low user acceptability, including low flow rate, taste and odor issues, high cost, recontamination, and ineffectiveness at treating common pathogens. An ultraviolet (UV) POU system was constructed utilizing developing community-appropriate materials and simple construction techniques based around an inexpensive low-wattage, low pressure UV bulb. The system was tested at the bench scale to characterize its hydrodynamic properties and microbial disinfection efficacy. Hydraulically the system most closely resembled a plug flow reactor with minor short-circuiting. The system was challenge tested and validated for a UV fluence of 50 mJ/cm2 and greater, over varying flow rates and UV transmittances, corresponding to a greater than 4 log reduction of most pathogenic bacteria, viruses, and protozoa of public health concern. This study presents the designed system and testing results to demonstrate the potential architecture of a low-cost, open-source UV system for further prototyping and field-testing.

scholarly journals Assessment of a low-cost, point-of-use, ultraviolet water disinfection technology

2007 ◽  
Vol 6 (1) ◽  
pp. 53-65 ◽  
Author(s):  
Sarah A. Brownell ◽  
Alicia R. Chakrabarti ◽  
Forest M. Kaser ◽  
Lloyd G. Connelly ◽  
Rachel L. Peletz ◽  
...  
Keyword(s):  
Rural Communities ◽  
Residence Time ◽  
Low Cost ◽  
Plug Flow ◽  
Field Studies ◽  
Water Disinfection ◽  
Galvanized Steel ◽  
Hydraulic Residence Time ◽  
Biological Assays ◽  
Point Of Use

We describe a point-of-use (POU) ultraviolet (UV) disinfection technology, the UV Tube, which can be made with locally available resources around the world for under $50 US. Laboratory and field studies were conducted to characterize the UV Tube's performance when treating a flowrate of 5 L/min. Based on biological assays with MS2 coliphage, the UV Tube delivered an average fluence of 900±80 J/m2 (95% CI) in water with an absorption coefficient of 0.01 cm−1. The residence time distribution in the UV Tube was characterized as plug flow with dispersion (Peclet Number = 19.7) and a mean hydraulic residence time of 36 s. Undesirable compounds were leached or produced from UV Tubes constructed with unlined ABS, PVC, or a galvanized steel liner. Lining the PVC pipe with stainless steel, however, prevented production of regulated halogenated organics. A small field study in two rural communities in Baja California Sur demonstrated that the UV Tube reduced E. coli concentrations to less than 1/100 ml in 65 out of 70 samples. Based on these results, we conclude that the UV Tube is a promising technology for treating household drinking water at the point of use.

scholarly journals Disinfection Performance of a Drinking Water Bottle System With a UV Subtype C LED Cap Against Waterborne Pathogens and Heterotrophic Contaminants

2021 ◽  
Vol 12 ◽  
Author(s):  
Richard M. Mariita ◽  
Sébastien A. Blumenstein ◽  
Christian M. Beckert ◽  
Thomas Gombas ◽  
Rajul V. Randive
Keyword(s):  
Public Health ◽  
Pathogenic Bacteria ◽  
Heterotrophic Bacteria ◽  
Health Concern ◽  
Plate Count ◽  
Rrna Gene ◽  
Stationary Condition ◽  
Subtype C ◽  
Public Health Concern ◽  
Log Reduction

The purgaty One systems (cap+bottle) are portable stainless-steel water bottles with UV subtype C (UVC) disinfection capability. This study examines the bottle design, verifies disinfection performance against Escherichia coli, Pseudomonas aeruginosa, Vibrio cholerae, and heterotrophic contaminants, and addresses the public health relevance of heterotrophic bacteria. Bottles were inoculated with deliberately contaminated potable water and disinfection efficacy examined using colony forming unit (CFU) assay for each bacterial strain. The heterotrophic plate count (HPC) method was used to determine the disinfection performance against environmental contaminants at day 0 and after 3days of water in stationary condition without prior UVC exposure. All UVC irradiation experiments were performed under stationary conditions to confirm that the preset application cycle of 55s offers the desired disinfection performance under-tested conditions. To determine effectiveness of purgaty One systems (cap+bottle) in disinfection, inactivation efficacy or log reduction value (LRV) was determined using bacteria concentration between UVC ON condition and controls (UVC OFF). The study utilized the 16S ribosomal RNA (rRNA) gene for characterization of isolates by identifying HPC bacteria to confirm if they belong to groups that are of public health concern. Purgaty One systems fitted with Klaran UVC LEDs achieved 99.99% inactivation (LRV4) efficacy against E. coli and 99.9% inactivation (LRV3) against P. aeruginosa, V. cholerae, and heterotrophic contaminants. Based on the 16S rRNA gene analyses, the study determined that the identified HPC isolates from UVC irradiated water are of rare public health concern. The bottles satisfactorily inactivated the target pathogenic bacteria and HPC contaminants even after 3days of water in stationary condition.

scholarly journals A compact point-of-use water purification cartridge for household use in developing countries

2014 ◽  
Vol 13 (1) ◽  
pp. 91-102 ◽  
Author(s):  
Rajshree A. Patil ◽  
Dilshad Ahmad ◽  
Shankar B. Kausley ◽  
Pradeep L. Balkunde ◽  
Chetan P. Malhotra
Keyword(s):  
Developing Countries ◽  
Water Purification ◽  
Low Cost ◽  
Cost Effective ◽  
Waterborne Diseases ◽  
Log Reduction ◽  
Effective Gravity ◽  
Point Of Use ◽  
Low Concentrations ◽  
Gravity Driven

Simple, low-cost household interventions are known to be effective in lowering the incidence of waterborne diseases in developing countries. However, high costs along with operational and maintenance issues have prevented the successful adoption of these interventions among the affected communities. To address these limitations, a cost-effective, gravity-driven water purification cartridge has been developed by employing the synergistic disinfection action of low concentrations of silver and chlorine on bacteria and viruses. The silver and chlorine treatment components within the cartridge have been developed using inexpensive materials and integrated with a life indicator and auto-shut-off-mechanism within a compact form factor. The antibacterial as well as antiviral performance of the cartridge was tested by using ground water spiked with Escherichia coli and MS2 bacteriophage. The results show that, although individually, the silver and chlorine treatment systems were unable to inactivate the test strains, the integrated cartridge inactivates both bacteria as well as viruses up to the log reduction requirement of the USEPA guide standard for microbiological water purifiers over its designated life of 2,000 liters.

scholarly journals Nanostructured catalysts for BIOEthanol transformation to industrially important chemicals

2021 ◽  
Vol 14 (1) ◽  
pp. 66-78
Author(s):  
Blažej Horváth ◽  
Matúš Petrík ◽  
Dana Gašparovičová ◽  
Tomáš Soták
Keyword(s):  
Flow Reactor ◽  
Low Cost ◽  
Plug Flow ◽  
Value Added ◽  
Nanostructured Catalysts ◽  
Product Distribution ◽  
Catalytic Transformation ◽  
Basic Catalysts ◽  
Acid Catalyzed ◽  
The Impact

Abstract Utilization of a low-cost biomaterial, such as bioethanol, to produce value–added compounds for current industry has been investigated. This work is focused on the catalytic transformation of bioethanol into industrially significant alkenes. Catalytic transformation of ethanol was studied using catalysts based mainly on nanostructured materials as Mg-Al hydrotalcites, sepiolites and zeolites doped with Cu, K, Sr, Zn and Mn. The catalytic tests were carried out in a plug-flow reactor in the temperature range of 350—550 °C. Undoped zeolites promote acid-catalyzed dehydration of ethanol, while in case of basic catalysts, such as hydrotalcites, the product distribution is shifted toward butadiene. The impact of the hydrotalcites preparation method on their structure and catalytic activity is reported. It was found that hydrotalcite with well-developed layered structure, prepared by slow hydrolysis, promotes the formation of butadiene (with butadiene yield of 28.2 % at 400 °C vs. ethylene yield of 17.2 % at 550 °C).

scholarly journals Removal of Antibiotics and Nutrients by Vetiver Grass (Chrysopogon zizanioides) from a Plug Flow Reactor Based Constructed Wetland Model

Toxics ◽  
2021 ◽  
Vol 9 (4) ◽  
pp. 84
Author(s):  
Saumik Panja ◽  
Dibyendu Sarkar ◽  
Zhiming Zhang ◽  
Rupali Datta
Keyword(s):  
Reaction Kinetics ◽  
Constructed Wetland ◽  
Pathogenic Bacteria ◽  
Flow Reactor ◽  
Plug Flow ◽  
Primary Source ◽  
Green Technology ◽  
Plug Flow Reactor ◽  
Vetiver Grass ◽  
Nitrogen And Phosphorus

Overuse of antibiotics has resulted in widespread contamination of the environment and triggered antibiotic resistance in pathogenic bacteria. Conventional wastewater treatment plants (WWTPs) are not equipped to remove antibiotics. Effluents from WWTPs are usually the primary source of antibiotics in aquatic environments. There is an urgent need for cost-effective, environment-friendly technologies to address this issue. Along with antibiotics, nutrients (nitrogen and phosphorus) are also present in conventional WWTP effluents at high concentrations, causing environmental problems like eutrophication. In this study, we tested vetiver grass in a plug flow reactor-based constructed wetland model in a greenhouse setup for removing antibiotics ciprofloxacin (CIP) and tetracycline (TTC), and nutrients, N and P, from secondary wastewater effluent. The constructed wetland was designed based on a previous batch reaction kinetics study and reached a steady-state in 7 days. The measured concentrations of antibiotics were generally consistent with the modeling predictions using first-order reaction kinetics. Vetiver grass significantly (p < 0.05) removed 93% and 97% of CIP and TTC (initial concentrations of 10 mg/L), simultaneously with 93% and 84% nitrogen and phosphorus, respectively. Results show that using vetiver grass in constructed wetlands could be a viable green technology for the removal of antibiotics and nutrients from wastewater.

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.

A stochastic model for two-station hydraulics exhibiting transient impact

1997 ◽  
Vol 36 (5) ◽  
pp. 19-26 ◽  
Author(s):  
J. L. Jacobsen ◽  
H. Madsen ◽  
P. Harremoès
Keyword(s):  
Parameter Estimation ◽  
Flow Reactor ◽  
Deterministic Model ◽  
Plug Flow ◽  
Stochastic Methods ◽  
Sewer System ◽  
Statistical Tool ◽  
Water Level Variation ◽  
Deterministic Description ◽  
Linear Reservoir

The objective of the paper is to interpret data on water level variation in a river affected by overflow from a sewer system during rain. The simplest possible, hydraulic description is combined with stochastic methods for data analysis and model parameter estimation. This combination of deterministic and stochastic interpretation is called grey box modelling. As a deterministic description the linear reservoir approximation is used. A series of linear reservoirs in sufficient number will approximate a plug flow reactor. The choice of number is an empirical expression of the longitudinal dispersion in the river. This approximation is expected to be a sufficiently good approximation as a tool for the ultimate aim: the description of pollutant transport in the river. The grey box modelling involves a statistical tool for estimation of the parameters in the deterministic model. The advantage is that the parameters have physical meaning, as opposed to many other statistically estimated, empirical parameters. The identifiability of each parameter, the uncertainty of the parameter estimation and the overall uncertainty of the simulation are determined.

Efficient Production of Light Olefin Based on Methanol Dehydration: Simulation and Design Improvement

2020 ◽  
Vol 23 ◽  
Author(s):  
S. Majid Abdoli ◽  
Mahsa Kianinia
Keyword(s):  
Dimethyl Ether ◽  
Flow Reactor ◽  
New Technology ◽  
Plug Flow ◽  
Light Olefins ◽  
Efficient Production ◽  
Actual Process ◽  
Light Olefin ◽  
Aspen Hysys ◽  
Improved Design

Background: Ethylene, propylene, and butylene as light olefins are the most important intermediates in the petrochemical industry worldwide. Methanol to olefins (MTO) process is a new technology based on catalytic cracking to produce ethylene and propylene from methanol. Aims and Objective: This study aims to simulate the process of producing ethylene from methanol by using Aspen HYSYS software from the initial design to the improved design. Methods: Ethylene is produced in a two-step reaction. In an equilibrium reactor, the methanol is converted to dimethyl ether by an equilibrium reaction. The conversion of the produced dimethyl ether to ethylene is done in a conversion reactor. Changes have been made to improve the conditions and get closer to the actual process design done in the industry. The plug flow reactor has been replaced by the equilibrium reactor, and the distillation column was employed to separate the dimethyl ether produced from the reactor. Result and Conclusion: The effect of the various parameters on the ethylene production was investigated. Eventually, ethylene is

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