Download or read book Report on Control of Micro Organisms in Cooling Towers Evaporative Condensers by Ultraviolet Disinfection for Ultraviolet Technology of Australasia Pty Ltd written by and published by . This book was released on 1989 with total page 42 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Practical Aspects of UV Disinfection written by Erin D. Mackey and published by American Water Works Association. This book was released on 2001 with total page 202 pages. Available in PDF, EPUB and Kindle. Book excerpt: This study evaluates long-term performance and feasibility of UV disinfection and develops criteria for selecting technology designed to prevent against Cryptosporidium . Chapters provide background information, describe the materials and methods used, discuss the inactivations of microorganisms by
Download or read book Ultraviolet disinfection guidance manual written by and published by DIANE Publishing. This book was released on 2003 with total page 478 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 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 Susceptibility of Multiple Strains of C Parvum to UV Light written by Jennifer L. Clancy and published by American Water Works Association. This book was released on 2002 with total page 70 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Microbiology of Cooling Water written by James W. McCoy and published by . This book was released on 1980 with total page 280 pages. Available in PDF, EPUB and Kindle. Book excerpt: management of cooling water systems and the bacteria that live in them. Includes studies and testing of microbicides and other microorganisms that infest recirculating cooling water systems and factors influencing their health and growth. Tests biological oxidation processes as a way of reusing treated effluents as an important method of water conservation in the petroleum refining and chemical processing industries. Explores practical methods for controlling microorganisms in cooling water; including working with chlorine dioxide as a microbicide. Methods are given for identifying and evaluating toxicants and bacteria that lead to fouling and staining of cooling water systems.
Download or read book Microbial Contamination Control Facilities written by Robert S. Runkle and published by . This book was released on 1969 with total page 218 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Ultraviolet Light Disinfection Technology in Drinking Water Application written by Science Applications International Corporation and published by . This book was released on 1996 with total page 276 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Investigation of Microbiological Regrowth After Ultraviolet Disinfection written by Daniel T. Ma and published by . This book was released on 2020 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Ultraviolet (UV) disinfection provides chemical free inactivation of a wide range of microorganisms. One primary mechanism of UV inactivation of bacteria is through DNA damage, which inhibits bacterial replication and reproduction. The ability of bacteria to repair DNA damage raises concerns about the post-treatment safety of UV treated water, especially if bacteria repair and regrow under favorable conditions. A well-known repair process is photorepair, which can lead to photoreactivation of inactivated cells. To address this concern, UV disinfection processes can be optimized by selecting specific wavelengths and UV doses to prevent repair and regrowth in various water treatment contexts. Emerging UV technology, such as UV LED devices, can be tailored to emit specific wavelengths to prevent microbial repair. In this study, UV-LEDs with nominal wavelengths 265, 280, and 285 nm and combined 265 + 285 nm were applied in collimated beam tests to quantify inactivation and photoreactivation kinetics of E. coli. At UV doses above 25 mJ/cm2, which were not evaluated in previous UV disinfection studies, the inactivation efficacy was highest for 265 + 285 nm, followed by 265 nm, 285 nm, and 280 nm. Both time-based and photorepair fluence-based photoreactivation were quantified. After 40 mJ/cm2, photoreactivation was greater for 265 + 285 nm than 265 nm. This was unexpected because the contribution of 285 nm in the combined wavelength disinfection was expected to suppress repair due to protein damage. Inactivation kinetics and regrowth kinetics may impact accurate quantification of photoreactivation. Molecular detection methods are needed to measure DNA damage repair to distinguish regrowth from repair. Photorepair is a concern after UV disinfection for point of use and decentralized community water treatment. A quantitative microbial risk assessment (QMRA) algorithm was developed to estimate probability of infection associated with pathogenic E. coli in community drinking water systems where solar photorepair light exposure can occur. QMRA is a powerful tool for estimating public health risk of exposure when lacking data. Photoreactivation was determined as a function of effective photorepair fluence from sunlight and a pathogen dose-response of E. coli O157:H7 was used to estimate probability of infection. The objective of the QMRA was to determine contamination, UV treatment, light exposure, and water container conditions where the acceptable risk of 1 in 10,000 is exceeded in water consumption scenarios with and without photoreactivation. For concentrations less than 5.7 × 105 CFU/L, the acceptable risk is not exceeded for point of use consumption without photoreactivation. For concentrations 104 CFU/mL and less, photorepair light exposures less than 30 minutes will not exceed the acceptable risk. Thus, 30 minutes is proposed as a conservative bottled water shelf life due to photorepair, but this estimate depends on solar and water container material characteristics that affect photorepair fluence calculations and is complicated by solar disinfection effects. The QMRA supports UV disinfection as an effective treatment for immediate consumption as well as for disinfection at communal water taps. The QMRA approach could be expanded to quantifying pathogen photoreactivation in other UV disinfection applications.
Download or read book Disinfection Efficiency and Dose Measurement of Polychromatic UV Light written by Karl G. Linden and published by IWA Publishing. This book was released on 2004-01-01 with total page 140 pages. Available in PDF, EPUB and Kindle. Book excerpt: There is currently intense interest in the use of ultraviolet technology for helping to meet future regulations relating to improved microbial inactivation and decreased disinfection byproducts (DBPs). Much of this interest has been fueled by recent research indicating the effectiveness of UV technologies for the inactivation of Cryptosporidium. This scientific discovery, combined with proposed regulations concerning DBPs in the United States, has resulted in a need to evaluate the feasibility and effectiveness of UV irradiation for use as a disinfectant for drinking water.The objectives of this project were to:(1) develop and evaluate physical, chemical, and biological methods for calculating effective germicidal UV dose from medium-pressure (MP) and Pulsed-UV (P-UV) lamps;(2) establish a UV dose/log inactivation relationship for specific bacterial and viral indicators for MP and P-UV lamps;(3) determine the extent of photoreactivation and dark repair of heterotrophic bacteria after treatment by MP and P-UV lamps; and(4) compare the ability of MP and P-UV lamps to inactivate Cryptosporidium. Originally published by AwwaRF for its subscribers in 2003 This publication can also be purchased and downloaded via Pay Per View on Water Intelligence Online - click on the Pay Per View icon below
Download or read book Impact of Particles on Ultraviolet Disinfection of Bacteria in Water written by Raymond Edward Joseph Cantwell and published by . This book was released on 2007 with total page 624 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book Fate and Persistence of Pathogens Sunjected to Ultraviolet Light and Chlorine Disinfection written by Karl G. Linden and published by . This book was released on 2004 with total page 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 Ultraviolet Disinfection for Wastewater written by Water Environment Federation and published by . This book was released on 2015-04-03 with total page 234 pages. Available in PDF, EPUB and Kindle. Book excerpt: Developed in conjunction with the International Ultraviolet Association, Ultraviolet Disinfection for Wastewater: Low-Dose Application Guidance for Secondary and Tertiary Discharges serves as a guide for consultants, wastewater utilities, and operators and provides introductory information on the advantages (and disadvantages) of UV disinfection compared to other commonly used technologies. It also provides valuable information to regulatory agencies who review applications for the use of UV disinfection systems in water resource recovery facilities that are subject to discharge limits for bacteria under National Pollutant Discharge Elimination System permitting. Providing specific case study examples, UV Disinfection fills an existing gap in the design guidance that is available for UV disinfection for low-dose applications, which includes disinfection of secondary and tertiary wastewater effluent discharges to meet NPDES compliance. Table of Contents Chapter 1: Introduction Chapter 2: Ultraviolet Disinfection Process Concepts and Equipment Systems Chapter 3: Bioassay Methods to Determine the Ultraviolet Dose (Fluence) Delivery of an Ultraviolet System Chapter 4: Innovations and Advances in Ultraviolet Reactor Analysis and Validation Chapter 5: Process Design and System Sizing Chapter 6: Equipment Selection, Facility Design, and Project Delivery Chapter 7: Ultraviolet Project Delivery, Startup, and Commissioning Chapter 8: Operational Considerations Chapter 9: Case Studies
Download or read book Ultraviolet Disinfection Guidance Manual written by and published by . This book was released on 2003 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Impact of Ultraviolet Disinfection on Biofilm Growth in a Model Distribution System written by Nicole Lea Celine Giese and published by Ann Arbor, Mich. : University Microfilms International. This book was released on 2002 with total page 146 pages. Available in PDF, EPUB and Kindle. Book excerpt:
