Impact of Particles and Particle-microbe Interaction on UV Disinfection PDF Download
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Author: Hadas Mamane-Gravetz
Publisher:
ISBN:
Category : Bacillus subtilis
Languages : en
Pages : 480
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Book Description
Author: Hadas Mamane-Gravetz
Publisher:
ISBN:
Category : Bacillus subtilis
Languages : en
Pages : 480
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Book Description
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: 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: Robert Wayne Emerick
Publisher:
ISBN:
Category :
Languages : en
Pages : 330
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Book Description
Author:
Publisher: DIANE Publishing
ISBN: 1428900195
Category : Water
Languages : en
Pages : 478
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Book Description
![An Investigation of UV Disinfection Performance Under the Influence of Turbidity & Particulates for Drinking Water Applications [electronic Resource] PDF](https://books.google.com/books/content/images/frontcover/q6PBjwEACAAJ?fife=w80-h100)
Author: Liu, Guo
Publisher: University of Waterloo
ISBN:
Category :
Languages : en
Pages :
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Book Description
UV disinfection performance was investigated under the influence of representative particle sources, including wastewater particles from secondary effluent in a wastewater treatment plant, river particles from surface water, floc particles from coagulated surface water, floc particles from coagulated process water in a drinking water treatment plant, and soil particles from runoff water (planned). Low-pressure (LP) and medium-pressure (MP) UV dose-response of spiked indicator bacteria E. coli was determined using a standard collimated beam apparatus with respect to different particle sources. Significant impacts of wastewater suspended solids (3.13~4.8 NTU) agree with the past studies on UV inactivation in secondary effluents. An average difference (statistical significance level of 5% or a=5%) of the log inactivation was 1.21 for LP dose and 1.18 for MP dose. In river water, the presence of surface water particles (12.0~32.4 NTU) had no influence on UV inactivation at all LP doses. However, when the floc particles were introduced through coagulation and flocculation, an average difference (a=5%) of the log inactivation was 1.25 for LP doses and 1.12 for MP doses in coagulated river water; an average difference (a=5%) of the log inactivation was 1.10 for LP doses in coagulated process water. Chlorination was compared in parallel with UV inactivation in terms of particulate impacts. However, even floc-associated E. coli were too sensitive to carry out the chlorination experiment in the laboratory, indicating that chlorine seems more effective than UV irradiation on inactivation of particle-associated microorganisms. In addition, a comprehensive particle analysis supported the experimental results relevant to this study.
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:
Publisher: American Water Works Association
ISBN: 9781583213414
Category : Medical
Languages : en
Pages : 112
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Book Description
This research studied low pressure(LP), low pressure-high-output (LPHO, medium pressure(MP) and pulsed (PUV) UV Systems and their effects on various pathogens. Among the findings were: bacteria is more susceptible to UV light than viruses; some strains of E.coli had different dose responses without explanation; adenovirus serotypes 40 and 41 are highly resistant to UV inactivation and a residual disinfection process is recommended to follow UV disinfection. All details of the study and models are discussed thoroughly.
Author: Karl G. Linden
Publisher: IWA Publishing
ISBN: 1843396998
Category : Science
Languages : en
Pages : 124
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Book Description
Disinfection of wastewater is a necessary treatment process for protecting the public from potential exposure to pathogenic microorganisms because many wastewater effluents are discharged into water bodies that may be used for recreation or as future drinking water supplies. Two common forms of disinfection are chlorine and ultraviolet (UV) light. However, microorganisms differ in their susceptibility to UV and chlorine disinfectants. It is necessary to understand how different classes of pathogens respond to UV and chlorine disinfection processes in wastewater to better develop strategies for optimizing the treatment of pathogens in wastewater. It is also recognized that water quality may impact disinfection effectiveness, such as protection of pathogen by particles and disinfectant demand. This study investigated bacteria, viruses and protozoan pathogens. All species of bacteria tested were susceptible to both UV and chlorine, despite differences in antibiotic resistance and tendency to aggregate. Upon exposure to disinfection conditions that could indicate viability of the bacteria tested, but not culturability using common methods, it was found that UV and chlorine were effective in eliminating the capability of viable but non-culturable bacteria to resuscitate and become re-infective. Clostridium spores were resistant to free chlorine and UV disinfection but found to be susceptible to long exposure to monochloramine. Cryptosporidium was resistant to all chlorine forms but very susceptible to UV irradiation. Pathogenic and indicator viruses tested were very susceptible to free chlorine and UV disinfection. UV radiation throughout the 200 to 300 nm range was effective for inactivation of viruses and C. parvum, but wavelengths between 260-270 nm and below 220 nm appeared to be more effective for viruses, suggesting a possible advantage for polychromatic UV sources. Sequential disinfection strategies were proposed and tested to enhance inactivation of various microorganisms. One scenario integrated UV disinfection followed by dynamic chloramination through addition of free chlorine and subsequent transformation to combined chlorine. Further, disinfection of microorganisms in wastewater presents challenges that are inherent to the water matrix, such as pathogens associated with particles. UV and chlorine were both effective for disinfection of coliform in wastewater but chlorine was found to be more effective during long contact times for inactivation of particle associated coliform. In addition to coliform, both Cryptosporidium parvum and Salmonella typhimurium were identified as being particle associated in wastewater using molecular approaches developed to detect microbes in environmental samples
Author: Michael H. Gerardi
Publisher: John Wiley & Sons
ISBN: 0471710423
Category : Science
Languages : en
Pages : 191
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Book Description
A practical guide to wastewater pathogens The fourth volume in Wiley's Wastewater Microbiology series, Wastewater Pathogens offers wastewater personnel a practical guide that is free of overly technical jargon. Designed especially for operators, the text provides straight facts on the biology of treatment as well as appropriate protective measures. Coverage includes: * An overview of relevant history, hazards, and organisms * Viruses, bacteria, and fungi * Protozoa and helminthes * Ectoparasites and rodents * Aerosols, foam, and sludge * Disease transmission and the body's defenses * Removal, inactivation, and destruction of pathogens * Hygiene measures, protective equipment, and immunizations
