Indicator organisms are used to assess public health risk in recreational waters, to highlight periods of challenge to drinking water treatment plants, and to determine the effectiveness of treatment and the quality of distributed water. However, many have questioned their efficacy for indicating pathogen risk. Five hundred and forty cases representing independent indicator–pathogen correlations were obtained from the literature for the period 1970–2009. The data were analyzed to assess factors affecting correlations using a logistic regression model considering indicator classes, pathogen classes, water types, pathogen sources, sample size, the number of samples with pathogens, the detection method, year of publication and statistical methods. Although no single indicator was identified as the most correlated with pathogens, coliphages, F-specific coliphages, Clostridium perfringens, fecal streptococci and total coliforms were more likely than other indicators to be correlated with pathogens. The most important factors in determining correlations between indicator–pathogen pairs were the sample size and the number of samples positive for pathogens. Pathogen sources, detection methods and other variables have little influence on correlations between indicators and pathogens. Results suggest that much of the controversy with regards to indicator and pathogen correlations is the result of studies with insufficient data for assessing correlations.
Keywords: correlation, indicators, logistic regression, pathogens, sample size, water
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This project evaluated a medium pressure ultra-violet (UV) reactor downstream from a conventional surface water treatment plant to determine the UV dose delivered by the reactor. The data was compared with computational fluid dynamics (CFD) results under the same test conditions to determine if CFD could accurately predict the dose.
The UV disinfection reactor was challenge tested with MS2 coliphage at a flowrate of 200 gpm and 600 gpm. The CFD model gave...
An ecosystem approach was adopted to investigate the interactions among anthropogenic habitat alterations, overcrowding, water insecurity, and enteric diseases in young children in Mexico City. A geographic information system (GIS) was used to define eligible wells and surrounding homesteads. Water quality was obtained from previously published investigations, and bacterial indicators included fecal coliforms and fecal streptococci. A cross-sectional survey was conducted during the rainy season 2002. A total of...
The Middle Chattahoochee River Watershed in western Georgia is undergoing rapid urban development. Consequently, Georgia’s water quality is threatened by extensive development as well as other land uses such as grazing. Maintenance of stream water quality, as land development occurs, is critical for the protection of drinking water, biotic integrity, and stream morphology. A two-phase, watershed-scale study was established to develop relationships among land use and water quality within western Georgia. During...
The resistance pattern and mechanisms of bacterial isolates obtained from clinical origin, soil, industrial effluent, orange juice products and drinking water were studied using commonly used antibiotics. The microbial load of the water samples, industrial effluent and orange juice products were 1.0 × 101–2.25 × 106, 2.15 × 105, and 3.5 × 104–2.15 × 105 cfu mL–1, respectively. The faecal coliform test revealed that only two out of twenty orange juice products had MPN of 2 and 20, the MPN of water ranged from...
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As the annual onslaught
of blue-green algae (cyanobacteria) blooms continues to plague fresh water lakes
and reservoirs, the use of copper sulfate to control the problem has become dubious.
After 50 years of pouring innumerable tons of copper into lakes and reservoirs,
the use of this algaecide has increased resistance and resulted in consequential
problems that require more expensive treatment and threaten marine habitats throughout
the world.Although
naturally present in...
Two regional studies conducted during dry weather demonstrated that the Southern California Bight (SCB) shoreline has good water quality, except near areas that drain land-based runoff. Here, we repeat those regional studies 36 h after a rainstorm to assess the influence of runoff under high flow conditions. Two hundred and fifty-four shoreline sites between Santa Barbara, California and Ensenada, Mexico were sampled using a stratified-random sampling design with four strata: sandy beaches, rocky shoreline,...
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.
To view the full article click here (PDF -...
Up to now, the recovery of precious metals used as catalysts in chemical processes has involved the use of incineration. Now, however, a British-Swedish joint venture has developed a process which uses supercritical water oxidation instead, which provides many economic and environmental advantages.
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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...
Industrial hygiene is the recognition, evaluation, and control of chemical, physical, biological, and ergonomic stresses in the workplace. Of the stresses listed, chemical stresses in the form of air contaminants are the most common. Air contaminants, their PELs and TLVs, and how to sample for them, is Industrial Hygiene 101 for most industrial hygienists. However, as simple as sampling and analysis may seem at first glance, every industrial hygienist or industrial hygiene chemist has at one time or another ended...
Introduction
Danfoss is a global manufacturer of hermetic compressors, pumps, valves, motors and other electrical control units. The company owns a major manufacturing facility located on a small island, Als, in the Baltic Sea. In 1983 the company was routinely withdrawing two million cubic meters of fresh water from the sole aquifer which supplies the entire island, home to 50,000 residents. This was well within the limit of three million cubic meters authorized by local officials.
In 1983, Danfoss discovered...
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...
A wave of privatization is rolling through the water industry – at the environment‘s expense? In order to provide an answer to this question, the Environmental-Rating agency oekom research AG, Munich, put a number of water supply companies and manufacturers of water appliances to the environmental test. In results published today, oekom identifies the British water supplier Severn Trent as the environmental leader of the water supply group with a B grade in the overall Environmental-Rating. The Austrian water...
Within the last decade, implementation of state and federal regulations and other local codes have changed biosolids processing in Florida. Previously, biosolids stabilization varied greatly among the state’s 3,500 to 4,000 wastewater treatment facilities. Public and privately owned wastewater treatment facilities were required to stabilize their biosolids to a minimum Class C standard for land application, with most facilities using aerobic or anaerobic digestion. Requirements for septage solids stabilization,...
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...
The fact that not all compost is created equal has both producers and growers looking for ways to successfully evaluate compost quality. Traditional compost analysis has focused on NPK and micronutrient concentrations in an effort to mirror fertilizer analysis. Compost, however, is much more complex than fertilizer and its most significant value to the grower may be far more than its mineral contribution to the soil. Compost has an important microbiological component that impacts how it will perform as a soil...
Background
The Printing Office (TPO) is a medium sized print shop employing 15 staff. It specialises in the production of high quality, short run jobs.
In the printing industry, the use of solvents has always been a problem. Whether it is from the point of view of workplace health and safety or from environmental concern, any reduction in the use of solvents is a welcome change. Motivated by these issues, TPO decided to trial a new dampener roller washer system that uses no solvents.
Issue
The offset...
Introduction Sustainability or `sustainable development` has become a term which is frequently applied to land use and social planning and resource issues. Sustainability is a concept which draws attention to development practices which can degrade natural ecosystems and deplete natural resources. If development is defined broadly to include any cultural activity, then sustainable development may be defined as any practice that meets the needs of the present population without compromising the ability of future...
` In order to determine the impacts of a particular discharge on ambient water quality, it is usually necessary to model the diffusion and dispersion of the discharge in the relevant water body. The approach applies both to new discharges and to upgrading of existing sources. This note provides guidance on models that may be applicable in the context of typical Bank projects.`
Introduction
Mathematical models can be used to predict changes in ambient water quality due to changes in discharges of wastewater. In...
Introduction
Any new technology must overcome perceptions of the marketplace, which are not accurate. As a technology moves into new areas of application, new misconceptions also arise. Crossflow membrane technology is no exception.
The first man-made, pressure-driven `crossflow` membranes were made in flat sheet form. This membrane had to be configured in a device, and was first made in tile obvious `plate-and-frame` design. The spiral-wound design resulted as a response to the high cost, large size, and...
SummaryWaste discharges from municipal sewage treatment plants are a significant source of water quality problems throughout the country. States report that municipal discharges are the main source of impairment to estuaries and coastal waters, the second leading source of impaired rivers and streams, and also are a major source of pollution in lakes. Pollutants associated with municipal discharges include nutrients (which can stimulate growth of algae that deplete dissolved oxygen in surface water), bacteria and...
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