Abstract:The growing scarcity of potable water supplies is among the most important issues facing many cities, in particular those using single sources of water that are climate dependent. Consequently, urban centers are looking to alternative sources of water supply that can supplement variable rainfall and meet the demands of population growth. A diversified portfolio of water sources is required to ensure public health, as well as social, economical and environmental sustainability. One of the options considered is the augmentation of drinking water supplies with advanced treated recycled water. This paper aims to provide a state of the art review of water recycling for drinking purposes with emphasis on membrane treatment processes. An overview of significant indirect potable reuse projects is presented followed by a description of the epidemiological and toxicological studies evaluating any potential human health impacts. Finally, a summary of key operational measures to protect human health and the areas that require further research are discussed.
A case-crossover study was undertaken to investigate the relationship between daily air pollutant concentrations and daily hospitalizations for selected disease categories in Perth, Western Australia. Daily measurements of particles (measured by nephelometry and PM2.5), photochemical oxidants (measured as ozone), nitrogen dioxide (NO2) and carbon monoxide (CO) concentrations were obtained from 1992 to 1998 via a metropolitan network of monitoring stations. Daily PM2.5 concentrations were estimated using monitored data, modelling and interpolation. Hospital morbidity data for respiratory, cardiovascular (CVD), gastrointestinal (GI) diseases, chronic obstructive pulmonary diseases (COPD) excluding asthma; pneumonia/influenza diseases; and asthma were obtained and categorized into all ages, less than 15 years and greater than 65 years. Gastrointestinal morbidity was used as a control disease. The data were analyzed using conditional logistic regression. The results showed a small number of significant associations for daily changes in particle concentrations, nitrogen dioxide and carbon monoxide for the respiratory diseases, CODP, pneumonia, asthma and CVD hospitalizations. Changes in ozone concentrations were not significantly associated with any disease outcomes. These data provide useful information on the potential health impacts of air pollution in an airshed with very low sulphur dioxide concentrations and lower nitrogen dioxide concentrations commonly found in many other cities.
The quality and safety of reverse osmosis (RO)-treated secondary wastewater, for indirect potable re-use, was assessed using a dataset of 375 chemicals measured in RO-treated wastewater. A screening health risk assessment indicated that four N-nitrosamines were of potential concern, although median concentrations of these chemicals were always below health values. The most frequently detected chemicals in RO-treated water were disinfection by-products, volatile organic compounds, metals and complexing agents, in contrast to many monitoring programs that focus on pharmaceuticals, personal care products and hormones. Frequent detections in RO-treated wastewater were most related to high concentrations in secondary wastewater, relative to limit of reporting, and the potential for chemicals to form or be added during the treatment process, rather than poor rejection by RO membranes. Between 3.7 and 10.7 μg/L of dissolved organic carbon (DOC) in RO permeate could be attributed from chemicals detected on at least one occasion, with the majority of this total attributed to chemicals detected in less than 25% of samples. While chemicals below detection may contribute a significant component of DOC, it is likely that natural organic matter and soluble microbial products still contribute the majority of DOC to RO permeate.
2A high degree of safety is demonstrated for the use of RO-treated wastewater as an indirect source of potable water.
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