Download or read book UV Inactivation of Viruses in Natural Waters written by Gregory A. Snicer and published by American Water Works Association. This book was released on 2000 with total page 132 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Inactivation of Pathogens with Innovative UV Technologies written by and published by American Water Works Association. This book was released on 2004 with total page 112 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book Inactivation of Viruses in Water by Ultraviolet Irradiation written by Stephanie Leah Molloy and published by . This book was released on 1997 with total page 150 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Inactivation of Virus in Natural Water and Wastewater by Silicate Minerals written by Shiao Huei Lo and published by . This book was released on 1970 with total page 102 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Sunlight Inactivation of Waterborne Viruses written by Andrea Idette Silverman and published by . This book was released on 2013 with total page 111 pages. Available in PDF, EPUB and Kindle. Book excerpt: Sunlight inactivation of microorganisms is a natural process that can occur in any sunlit water and has implications for microbial ecology, the fate of microbial contaminants in the environment, and natural wastewater treatment systems. This work focuses on sunlight inactivation of waterborne viruses, which present a special challenge in health-related water microbiology given that waterborne human viruses are important etiologies of disease, and are difficult to remove and inactivate in water. The research presented in this dissertation builds upon previous research by determining the mechanisms and rates of sunlight inactivation of human viruses in natural waters; these data were used to build predictive inactivation rate models that account for virus type, sunlight irradiance and water quality. Additionally, two applications of sunlight inactivation - the differential stability of indicator organisms and human viruses in the environment, and disinfection of irrigation water in wastewater-irrigated agriculture - were investigated. There are three proposed sunlight inactivation mechanisms for viruses: the direct- and indirect-endogenous mechanisms, which require absorption of photons by virus components, and the exogenous mechanism, which involves reaction between the virus and exogenously produced reactive intermediates formed by photochemical reactions. All three mechanisms are affected by water quality. Natural organic matter, for example, is found in most aquatic environments and is capable of both attenuating sunlight - which would decrease sunlight exposure and therefore inactivation rates - and photosensitizing production of reactive intermediates - which could increase inactivation rates of viruses susceptible to the exogenous mechanism. The first goal of this dissertation was to better understand the mechanisms of sunlight inactivation of select bacteriophage and human viruses in surface waters containing natural organic matter. Given the two main modes by which damage is delivered to viruses in sunlit surface waters - through direct absorption of photons (the direct- and indirect-endogenous mechanisms) and contact with reactive molecules formed by sensitizers in the water column (the exogenous mechanism) - a better understanding of sunlight inactivation mechanisms can help us predict how environmental conditions (e.g., sunlight irradiance, light attenuation, water quality, depth, mixing) can affect observed inactivation rates. Through laboratory experiments using simulated sunlight and natural organic matter-containing waters collected from the environment, we determined that the sunlight inactivation rates of human poliovirus type 3 and bacteriophage PRD1 mainly involved endogenous inactivation mechanisms, while MS2 and human adenovirus type 2 were also affected by the exogenous mechanism. Different virus types were found to have different rates of inactivation, and inactivation rates differed among water types depending on light attenuation and natural organic matter in the water source; this finding made it clear that water quality conditions and virus type must be taken into account when predicting inactivation rates. Additionally, MS2 was inactivated at the slowest rate in all waters, and PV3 the fastest, at the water depth that was studied (i.e., 5 cm). The data obtained in the initial virus inactivation study, along with findings from other researchers, were used to develop and test models that predict the sunlight inactivation rates of viruses in surface waters containing light-attenuating photosensitizers. Models were developed for poliovirus type 3 and MS2. Inactivation rates were modeled and measured in reactors containing different, well-mixed depths of water collected from an open-water wastewater treatment system; the models performed well in predicting inactivation rates in laboratory experiments. Given the tradeoff between decreased endogenous inactivation due to light attenuation and increased exogenous inactivation due to the presence of photosensitizers in natural organic matter-containing water, we compared the measured and modeled inactivation rates of poliovirus type 3 (which is reliant on endogenous mechanisms) and MS2 (which is susceptible to the exogenous mechanism) at different well-mixed depths. The inactivation rate of poliovirus type 3 was found to be lower than that of MS2 at deeper well-mixed depths, indicating that MS2 cannot be considered a conservative indicator of poliovirus sunlight inactivation under all conditions. Some research gaps - including the development of models that take into account the solar zenith angle, annual and diurnal variation in irradiance, and water body hydraulics - must be filled to successfully translate the models to environmental waters and natural sunlight. Many viruses are not culturable, making them difficult to study in general, let alone their inactivation rates. To better understand factors that dictate differences in sunlight inactivation rates between viruses, which could help in predicting inactivation rates of non-culturable viruses, we investigated whether sunlight inactivation of poliovirus type 3 is caused by damage to the protein capsid of the virus. More specifically, this research focused on the inhibition of viral `life' processes that depend on an intact capsid. Comparing data from assays that quantify host cell attachment and infectivity, we found that although sunlight exposure leads to an inhibition of poliovirus type 3 attachment to host cells (which is the first step in the infection process), this damage mechanism plays a minor role in total inactivation. The second part of this dissertation focuses on a case study of wastewater irrigation practiced in Accra, Ghana, with goals to better understand the health risks associated with wastewater irrigation in Accra, and to determine whether small, farmer-dug ponds can contribute to disinfection of irrigation water. To provide data that can be used to refine quantitative microbial risk assessment models of wastewater-fed agriculture in Accra, irrigation water samples were analyzed for concentrations of fecal indicator microorganisms (human-specific Bacteroidales, E. coli, enterococci, thermotolerant coliform, and F+ and somatic coliphages) and two human viruses (adenovirus and norovirus genogroup II). E. coli concentrations in all samples exceeded recommended limits set by the World Health Organization, human viruses were detected in 75% of samples analyzed, and virus concentrations were quantified in 60% of samples. Indicator organism and virus concentrations were compared as part of an analysis of differential stability of fecal indicator organisms and pathogens in the environment, and the appropriateness of assumptions used in quantitative microbial risk assessment to relate indicator organism concentrations to those of pathogens. After determining indicator organism and pathogen concentrations in Accra irrigation water, we investigated the ability of a farmer-developed intervention (small, on-farm ponds) to disinfect wastewater before use in vegetable irrigation. Results indicated that sunlight inactivation dominated the removal of two bacteria (E. coli and enterococci) and two bacteriophages (F+ and somatic coliphages) in these ponds, and that the ponds can contribute to the multi-barrier approach to reducing health risks related to wastewater irrigation. On-farm pond design and management recommendations, as well as challenges, are also discussed.

Download or read book Inactivation of Bacteria and Viruses in Water Using Ultraviolet Light and Advanced Oxidation Processes in a Bench scale and Two Pilot scale Systems written by Majid Nikougoftar Zarif and published by . This book was released on 2017 with total page 87 pages. Available in PDF, EPUB and Kindle. Book excerpt: Adenoviruses cause gastrointestinal illnesses and have been listed on the U.S. EPA's Contaminant Candidate Lists (CCL). They are highly resistant to ultraviolet (UV) inactivation. Advanced oxidation processes (AOPs) are known to improve inactivation of microorganisms and simultaneously oxidize organics. The bacteriophage P22 was selected as a surrogate for adenoviruses due to their physical and genetic similarities. The main objective of this study was to compare the synergic disinfection potential of titanium dioxide (TiO2) or peracetic acid (PAA) with UV for viruses and bacteria in water. Both bench-scale and pilot-scale evaluation was done. A bench-scale collimated beam was included to evaluate the inactivation of P22 and E. coli by UV with and without TiO2 or PAA. A Purifics Photo-Cat system which is an integrated UV/ceramic membrane reactor was used for the pilot-scale TiO2-UV AOP experiments. For pilot-scale PAA-UV AOP experiments, an in-line D222 UV reactor unit provided by NeoTech Aqua Solutions, Inc. was used. TiO2 doses of 1, 10, and 40 mg/L were applied in the collimated beam and the Photo-Cat system. Higher TiO2 doses resulted in a higher inactivation in the Photo-Cat and lower inactivation in the collimated beam apparatus. Adding 40 mg/L of TiO2 in the photo-Cat system improved P22 inactivation by 25% while it slightly decreased P22 inactivation in collimated beam apparatus. PAA doses of 0.25 or 0.5 ppm were continuously injected upstream of the UV light and a 53% or 90% increase in inactivation was observed for E. coli, respectively, as compared to UV alone. However, P22 required higher dose with PAA-UV AOP and PAA concentrations of 1 or 10 ppm resulted in an 18% and 70% increase in the inactivation respectively, as compared to UV alone. Interestingly, when the same condition was applied to water with more organics (UVT 79%), E. coli exhibited the same level of susceptibility to PAA-UV AOP while P22 inactivation decreased. The results provide new insight on the effectiveness and applicability of adding AOP to UV for microbial inactivation in water. PAA-UV AOP can potentially enhance existing UV disinfection systems with minimal chemical addition, and a simple retrofit to existing UV units.

Download or read book Ultraviolet Light in Human Health Diseases and Environment written by Shamim I. Ahmad and published by Springer. This book was released on 2017-11-08 with total page 367 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is about the roles and importance of Ultraviolet (UV) light from sun and from man-made UV lamps in our daily life, on health and diseases, also its application in sterilization and treatment. The key words are: reactive oxygen species, DNA damage, UV mutagenicity, skin cancers, polymorphous light eruption, Xeroderma pigmentosum, vitiligo, psoriasis, rheumatoid arthritis, diabetes mellitus, metabolic syndromes, cardiovascular diseases, dermatology, photobiology, photodermatosis, vitamin D synthesis, vitamin D efficiency, water sterilization, blood sterilization, phototherapies, skin tanning and UV dosimeter. The book starts with introduction to UV light and the history of development of UV lamps and its applications. It then moves to describing the interaction of this light with biological components and the production of reactive oxygen species, their roles in cell signaling, cellular defense from foreign invaders, in mutagenesis leading to skin diseases including vitiligo, polymorphous light eruption and various forms of skin cancer. Then it presents the synthesis and importance of UV light and diseases, induced due to the deficiency of vitamin D. Roles of UV light in sterilization, disinfection, phototherapies are depicted in the next part and finally use and abuse of UV light in tanning salon and the availability and importance of use of UV dosimeter are highlighted. The three main focuses of this book are: - Damage to biological systems by UV light leading to certain skin diseases; most importantly skin cancers. - Importance of UV light in the in vivo synthesis of vitamin D when human bodies are exposed to it. - Diseases caused due to the deficiency of vitamin D and the use of UV lamps in phototherapy and sterilization processes. The editor has considerable experience in publishing medical books and has used it critically selecting the matters which will attract the readers from many areas of medical and non-medical fields. It is hoped that the materials presented in this book will give great benefit and will stimulate both novice and expert researchers in the field. The book gives excellent overviews of the current status of research and pointers to the future research achievements. Clinicians, medical general practitioners, technicians and staff working in UV related industries and especially those working in tanning salon should benefit from the information presented in safe handling of this light.

Download or read book Quantitative Microbial Risk Assessment written by Charles N. Haas and published by John Wiley & Sons. This book was released on 2014-06-09 with total page 439 pages. Available in PDF, EPUB and Kindle. Book excerpt: Provides the latest QMRA methodologies to determine infection risk cause by either accidental microbial infections or deliberate infections caused by terrorism • Reviews the latest methodologies to quantify at every step of the microbial exposure pathways, from the first release of a pathogen to the actual human infection • Provides techniques on how to gather information, on how each microorganism moves through the environment, how to determine their survival rates on various media, and how people are exposed to the microorganism • Explains how QMRA can be used as a tool to measure the impact of interventions and identify the best policies and practices to protect public health and safety • Includes new information on genetic methods • Techniques use to develop risk models for drinking water, groundwater, recreational water, food and pathogens in the indoor environment

Download or read book Ultraviolet Germicidal Irradiation Handbook written by Wladyslaw Kowalski and published by Springer Science & Business Media. This book was released on 2010-01-12 with total page 504 pages. Available in PDF, EPUB and Kindle. Book excerpt: This reference covers technical information on ultraviolet germicidal irradiation and its application to air and surface disinfection and the control of pathogens and allergens. Its main focus is airborne microbes and surface contamination applications.

Download or read book The Ultraviolet Disinfection Handbook written by James R. Bolton and published by American Water Works Association. This book was released on 2011-01-12 with total page 167 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Wastewater Pathogens written by Michael H. Gerardi and published by John Wiley & Sons. This book was released on 2004-10-28 with total page 191 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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

Download or read book Disinfection Profiling and Benchmarking Guidance Manual written by and published by . This book was released on 1999 with total page 196 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Research plan for microbial pathogens and disinfection byproducts in drinking water written by and published by DIANE Publishing. This book was released on with total page 173 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Management of Legionella in Water Systems written by National Academies of Sciences, Engineering, and Medicine and published by National Academies Press. This book was released on 2020-02-20 with total page 291 pages. Available in PDF, EPUB and Kindle. Book excerpt: Legionnaires' disease, a pneumonia caused by the Legionella bacterium, is the leading cause of reported waterborne disease outbreaks in the United States. Legionella occur naturally in water from many different environmental sources, but grow rapidly in the warm, stagnant conditions that can be found in engineered water systems such as cooling towers, building plumbing, and hot tubs. Humans are primarily exposed to Legionella through inhalation of contaminated aerosols into the respiratory system. Legionnaires' disease can be fatal, with between 3 and 33 percent of Legionella infections leading to death, and studies show the incidence of Legionnaires' disease in the United States increased five-fold from 2000 to 2017. Management of Legionella in Water Systems reviews the state of science on Legionella contamination of water systems, specifically the ecology and diagnosis. This report explores the process of transmission via water systems, quantification, prevention and control, and policy and training issues that affect the incidence of Legionnaires' disease. It also analyzes existing knowledge gaps and recommends research priorities moving forward.

Download or read book Coagulation and Flocculation in Water and Wastewater Treatment written by John Bratby and published by IWA Publishing. This book was released on 2006-10-15 with total page 421 pages. Available in PDF, EPUB and Kindle. Book excerpt: Coagulation and Flocculation in Water and Wastewater Treatment provides a comprehensive account of coagulation and flocculation techniques and technologies in a single volume covering theoretical principles to practical applications. Thoroughly revised and updated since the 1st Edition it has been progressively modified and increased in scope to cater for the requirements of practitioners involved with water and wastewater treatment. A thorough gamut of treatment scenarios is attempted, including turbidity, color and organics removal, including the technical aspects of enhanced coagulation. The effects of temperature and ionic content are described as well as the removal of specific substances such as arsenic and phosphorus. Chemical phosphorus removal is dealt with in detail, Rapid mixing for efficient coagulant utilization, and flocculation are dealt with in specific chapters. Water treatment plant waste sludge disposal is dealt with in considerable detail, in an Appendix devoted to this subject. Invaluble for water scientists, engineers and students of this field, Coagulation and Flocculation in Water and Wastewater Treatment is a convenient reference handbook in the form of numerous examples and appended information.

Download or read book Drinking Water Contaminant Candidate List written by and published by . This book was released on 1998 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book SARS and Other Coronaviruses written by Dave Cavanagh and published by Springer Science & Business Media. This book was released on 2008-09-02 with total page 368 pages. Available in PDF, EPUB and Kindle. Book excerpt: In 2003, the word "coronavirus" spread across the globe, somewhat further than the virus that sparked the panic. In this book, expert researchers examine these devastating viruses through 23 state-of-the-art, widely applicable protocols with minute detail. Comprehensive and cutting-edge, the book serves as an ideal guide for all virologists and especially for those working with coronaviruses. Written by international experts, this book is relevant to a wide array of professions.