Understanding the Effect of Particle-size on UV Disinfection PDF Download
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Author: Thiam-Chuan Tan
Publisher:
ISBN: 9780494400678
Category :
Languages : en
Pages : 248
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Book Description
This study aimed to better understand the impact of suspended particles on ultraviolet disinfection of municipal effluents. The results showed that particles of sizes greater than 45 gm accounted for more than 90% of the surviving coliform in the tailing region of secondary effluent UV dose-response curve. Particles in larger size fractions also showed a greater tailing propensity---the probability of particle surviving UV doses beyond 30 mJ/cm2. In modeling the disinfection performance of secondary effluents, this was found to be the summation of the disinfection of all its particulate constituents. It was therefore possible to predict UV dose-response curve based on measurements of effluent particle-size distribution and particle disinfection kinetics. Finally, the tailing propensity was found to greatly depend on treatment processes. Trickling filter particles exhibited ten times greater tailing propensity than activated sludge particles, owing to their greater UV resistance and percentage viability.
Author: Thiam-Chuan Tan
Publisher:
ISBN: 9780494400678
Category :
Languages : en
Pages : 248
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Book Description
This study aimed to better understand the impact of suspended particles on ultraviolet disinfection of municipal effluents. The results showed that particles of sizes greater than 45 gm accounted for more than 90% of the surviving coliform in the tailing region of secondary effluent UV dose-response curve. Particles in larger size fractions also showed a greater tailing propensity---the probability of particle surviving UV doses beyond 30 mJ/cm2. In modeling the disinfection performance of secondary effluents, this was found to be the summation of the disinfection of all its particulate constituents. It was therefore possible to predict UV dose-response curve based on measurements of effluent particle-size distribution and particle disinfection kinetics. Finally, the tailing propensity was found to greatly depend on treatment processes. Trickling filter particles exhibited ten times greater tailing propensity than activated sludge particles, owing to their greater UV resistance and percentage viability.
Author: Michael Richard Templeton
Publisher:
ISBN: 9780494157572
Category :
Languages : en
Pages : 482
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Book Description
Viruses are frequently attached onto or enmeshed within a variety of particles in natural waters and wastewaters, however relatively little is known about the impact of this viral particle-association on water treatment processes. This thesis focuses on the impact of particle-associated viruses on ultraviolet (UV) disinfection, a disinfectant currently gaining widespread popularity in the drinking water industry in North America. Particles smaller than 2 microns (mum) in diameter were shown to be large enough to enmesh and protect bacteriophages MS2 and T4 (model viruses) from UV light. This is smaller than the minimum particle size of 7-10 mum for the shielding of coliform bacteria from the UV disinfection of wastewater reported by earlier studies. In addition, particulate chemical composition, specifically UV-absorbing content such as organic or iron compounds, was a critical factor in the survival of particle-associated bacteriophage exposed to UV light. Particles such as humic acid floc, activated sludge floc, and iron precipitate particles were observed to protect attached phage from UV light. Dual-media filtration, which often precedes UV disinfection in surface water treatment, was shown to be an effective means of reducing the number of particle-associated phage. The breakthrough of particle-associated phage through an anthracite-sand filter was highest during periods of increased particle breakthrough (i.e. filter effluent turbidity> 0.3 NTU), especially at the end of the filter cycle. UV disinfection of phage in the filter effluent was negatively impacted during the end of filter cycle breakthrough conditions in some cases. In addition, it was observed that un-filterable humic acid particles smaller than 0.45 mum and/or humic acid coating of bacteriophage surfaces may have UV-protective effects. The research findings also re-emphasize that viral disinfection studies should account for particle-associated viruses using techniques such as the physico-chemical blending method that was used in this research, since failure to do so can result in significant underestimation of the true virus concentrations. Further, multiple viral surrogates should be used in experimental studies whenever possible, since viruses vary significantly in their sizes, shapes, and surface charges, all of which can influence the adsorption of viruses to particles.
Author: Hadas Mamane-Gravetz
Publisher:
ISBN:
Category : Bacillus subtilis
Languages : en
Pages : 480
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Author:
Publisher: ScholarlyEditions
ISBN: 1464991324
Category : Medical
Languages : en
Pages : 1339
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Book Description
Advances in Escherichia Research and Application / 2012 Edition is a ScholarlyEditions™ eBook that delivers timely, authoritative, and comprehensive information about Escherichia. The editors have built Advances in Escherichia Research and Application / 2012 Edition on the vast information databases of ScholarlyNews.™ You can expect the information about Escherichia in this eBook to be deeper than what you can access anywhere else, as well as consistently reliable, authoritative, informed, and relevant. The content of Advances in Escherichia Research and Application / 2012 Edition has been produced by the world’s leading scientists, engineers, analysts, research institutions, and companies. All of the content is from peer-reviewed sources, and all of it is written, assembled, and edited by the editors at ScholarlyEditions™ and available exclusively from us. You now have a source you can cite with authority, confidence, and credibility. More information is available at http://www.ScholarlyEditions.com/.
Author: Robert Wayne Emerick
Publisher:
ISBN:
Category :
Languages : en
Pages : 330
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Author: Sanjaya Amal Seneviratne
Publisher:
ISBN:
Category :
Languages : en
Pages : 106
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Author: Robert Wayne Emerick
Publisher:
ISBN:
Category :
Languages : en
Pages : 88
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Author:
Publisher: DIANE Publishing
ISBN: 1428900195
Category : Water
Languages : en
Pages : 478
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Author: Raymond Edward Joseph Cantwell
Publisher:
ISBN: 9780494394007
Category :
Languages : en
Pages : 624
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Book Description
When UV light is applied to disinfect drinking water, particles in the water can conceivably protect embedded microorganisms from disinfection. Earlier studies have investigated how turbidity and particles affect light scattering, and particle-associated protection of cultured microorganisms. Little attention has been devoted to the ability of natural particles in water supplies to protect indigenous microorganisms. This thesis focuses on humic-coating of bacteria, the optical properties of particles and particle-related protection of indigenous microorganisms. A bench-scale proof-of-concept study found that both commercial (AHA) and aquatic humic acid (Suwannee River natural organic matter) appears to coat the surface of cultured bacteria hindering the effectiveness of UV disinfection. Both AHA and Suwannee River NOM were found to offer statistically significant (alpha = 0.05) protection of both E. coli and B. subtilis at concentrations of 50 and 120 mg/L. The concentrations of humic matter used in the study (10 to 120 mg/L) exceed those commonly found in surface waters. The bulk LV254 absorbance by particulate material in 10 surface waters was found to be the same order of magnitude as particles from the secondary effluent of a municipal wastewater treatment facility. This implies that since wastewater particles can offer protection to embedded microorganisms from UV light, it is possible for surface water particles to offer similar protection, at least in terms of the optical properties of the particle material. Particle-related protection of indigenous coliforms in untreated surface water from 3 sources (turbidity from 0.8 to 5.4 NTU) was observed with protection attributed to particles> 11 microm. However, despite this protection, at least 2.5-log inactivation of indigenous coliform bacteria was observed in all waters considered. In another untreated surface water (up to 1.3 NTU), no strong evidence of protection of indigenous coliforms or aerobic spores was found. A final objective of this study was to use 14 months of hourly UVT data to evaluate the USEPA's Ultraviolet Disinfection Guidance Manual recommendations for UVT data collection and analysis for design of UV systems. In terms of sampling frequency, both hourly and daily (but not weekly) UVT data collection provided reliable data for UV reactor design.
Author: Shaghayegh Armioun
Publisher:
ISBN:
Category :
Languages : en
Pages :
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