Ultraviolet (UV) light water treatment reactors are commonly used in both wastewater and drinking water disinfection. UV technology can effectively inactivate a large number of pathogens at low UV doses, however adenovirus requires a substantially higher dose than most pathogens of interest. In order to meet adenovirus inactivation requirements, UV reactors are often placed in series and the total inactivation is calculated as the sum of the reactors' individual UV doses. In this paper, it is shown that this simple summation treatment of UV dose may be acceptable. A parameter called the reactor additivity factor is introduced to properly characterize the interaction between UV reactors in series. Three types of UV reactors are modelled using computational fluid dynamics, and their RAFs are computed. The validity of reactor additivity in practice in wastewater and drinking water systems is discussed.
Currently UV disinfection technologies available for use in drinking water and water reuse applications typically utilize one of three types of mercury UV lamps. These three types of mercury UV lamps include low pressure, low-pressure high-output, and medium-pressure lamps. All of these lamps contain electrodes that facilitate in the generation of UV radiation. These electrodes are of delicate construction and their deterioration is the primary source of failure in UV disinfection systems. An emerging UV disinfecti...
In April, 2001, Seattle Public Utilities (SPU) in Seattle, Washington, awarded CH2MHill Constructors Inc., a contract for the design, permitting, construction, and long-term facility operation for the City of Seattle’s Cedar Treatment Facility Design Build Operate Project. The City of Seattle set the following, overall water quality protection goals:
- Provide strong public health protection
- Comply with current and anticipated drinking water regulations
- Maintain and increase customer confidence in the...
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N-nitrosodimethylamine (NDMA) was first detected in 1990 as a problem pollutant in drinking water wells at levels as high as 3,000 ppt in Elmira, Ontario, Canada. The waste from a large chemical plant over many years had led to the contamination of the drinking water wells for the community. After extensive evaluation and testing, it was determined that UV photolysis was the most effective treatment method which led to the installation of a Calgon 270 kW Rayox®...
Ultraviolet Disinfection of varying quality wastewater effluent has been determined to be an effective alternative to the use of chemical Disinfection techniques. There are a number of alternative UV system formats available for consideration in plant and process design. The comparative strengths of various formats are examined in detail with specific attention to process efficacy, life cycle cost and manpower demands upon plant staff.
Case histories will be presented for operating sites including Disinfection...
Ultraviolet disinfection lights up municipal drinking water treatment systems
Ultraviolet radiation (UV), long a staple disinfectant in wastewater treatment, is gaining recognition as a beneficial technique in disinfection systems for municipal drinking water. Focusing on the North American market, this article reviews basics of this technology and provides up-to-date selection and application guidelines for its use in municipal drinking water treatment plants.
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EXECUTIVE SUMMARY
In recent years, considerable effort has been made in drinking water treatment research to develop methods with improved natural organic matter (NOM) removal from water. Reduction in the level of NOM before disinfection can minimise the formation of disinfection by-products and reduce the residual required to control bacterial regrowth in the distribution system. This contributes to a higher quality water that is delivered to the consumers.
This paper describes a laboratory study using (a)...
The maps in this atlas depict the waters within each state that do not meet state water quality standards. States listed these waters in their most recent submission to EPA, generally in 1998, as required by section 303(d) of the Clean Water Act. This provision of the Clean Water Act requires a “Total Maximum Daily Load” or TMDL for each listed water. There are more than 20,000 such waters identified nationally, comprising more than 300,000 miles of rivers and streams and more than 5 million acres of lakes. The...
1.1 Scope and Objectives
A small number of viable options are presently available for the bleaching of wood pulp (delignification and brightening) during the manufacture of pulp and paper. The use of chlorine dioxide (ClO2) in the bleaching process has largely superceded the earlier use of Cl2, or elemental chlorine, in the majority of North American pulp mills: It was discovered over a decade ago that the previous widespread use of Cl2 contributed to the production and subsequent release to the environment of...
Many of the Environmental Protection Agency`s (EPA`s) methods used to monitor air, water and soil for environmental contaminants prescribe step-by-step details on how the chemical analysis must be conducted and prohibit any deviations or variations. The EPA has recognized that monitoring equipment and technology have improved tremendously over the last few years; that environmental media do not always act the same way for each analysis; and that the matrix may affect the analysis and results. The EPA has been...
Abstract
Africa
The economic and social needs of Africa depends more on its environmental resources but these natural resources are seriously declining and that is really effecting the entire region. Sustainable development in this rapidly changing region has become an imperative, and must take place in the complex context of a diverse and changing ecosystem, political transition and evolution toward market economies.
The region is heading towards integrating environmental components into sectors like...
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The disinfection of pathogenic microbes in drinking water has been largely successful over the last century due to the use of chlorination. However, research conducted in the 1970's revealed that by-products formed during the chlorination process are potentially carcinogenic and that there is a direct correlation between the concentration of chlorination by-products and the probability of certain cancers and other health problems. Following these discoveries,...
It may be necessary to know other subsurface information to remediate nonhalogenated semivolatile organics in water. Treatability studies may be required to determine the contaminant biodegradability for any biodegradation technologies. Treatability studies are also necessary to ensure that the contaminated ground water can be treated effectively at the design flow. A subsurface geologic characterization would be particularly useful to any isolation or stabilization technologies. Ground water models are also...
It may be necessary to know other subsurface information to remediate halogenated semivolatile organics in water. Treatability studies may be required to determine the contaminant biodegradability for any biodegradation technologies. Treatability studies are also necessary to ensure that the contaminated ground water can be treated effectively at the design flow. A subsurface geologic characterization would be particularly useful to any isolation or stabilization technologies. Ground water models are also often...
Explosives-contaminated process waste waters can be subdivided into two categories: red water, which comes strictly from the manufacture of TNT, and pink water, which includes any washwater associated with load, assemble, and pack (LAP) operations or with the demilitarization of munitions involving contact with finished explosive. Despite their names, red and pink water cannot be identified by color. Both are clear when they emerge from their respective processes and subsequently turn pink, light red, dark red,...
The proliferation of bottled beverages worldwide and an increased awareness of consumer health issues have beverage bottlers rethinking how to keep their liquids safe for consumption. One problem they face is the need to deliver a product that is free of bacteria, to provide extended shelf life and product quality.
Ozone has quickly become the disinfectant of choice among water bottlers worldwide. Although ozone was `discovered` in the mid-19th century, it is only during the last several decades that its...
ABSTRACT
This technology report is an overview of information collected by GWRTAC on ultraviolet/oxidation as applied to ex-situ groundwater remediation. Information provided includes an introduction to the principles and techniques associated with this technology, a general discussion of its applicability to remediation, limited cost data relating to results of its use, and advantages and limitations of use of this technology.
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Summary:
Catalysts in water treatment speed chemical reactions so equipment can be scaled down or contact times shortened. Because the speed of a reaction can affect equipment price or useful life, it could mean the difference between a sale and a "no, thanks." Thus, recently developed catalytic activated carbons may enable water treatment dealers to take advantage of activated carbon's properties for applications previously deemed too costly for carbon, such as...
The disinfection of pathogenic microbes in drinking water has been largely successful over the last century due to the use of chlorination. However, research conducted in the 1970`s revealed that by-products formed during the chlorination process are potentially carcinogenic and that there is a direct correlation between the concentration of chlorination by-products and the probability of certain cancers and other health problems. Following these discoveries, drinking water regulators have struggled to find a...
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