Process reliability and significance of reclaimed water quality parameters

Microbial quality of reclaimed water can be adequately interpreted by graphical adjustment of experimental results to a lognormal probability distribution; the method serves to verify the degree of conformity to the proposed distribution and to visualize the time variability of the results. A conven...

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Bibliographic Details
Published in:Water science and technology 2008-01, Vol.57 (5), p.667-674
Main Authors: Mujeriego, R, Peters, K
Format: Article
Language:English
Subjects:
Bacteria
Chemical treatment
Deactivation
Disinfectants
Disinfection
Disinfection & disinfectants
Disinfection - methods
Dissolved organic matter
Distribution
dose response
Escherichia coli
helminths
Inactivation
indicator species
Indicators
Influents
microbial contamination
Microorganisms
Organic matter
probability analysis
Probability distribution
Probability theory
Reclaimed water
Reliability
Reproducibility of Results
Standard deviation
Treated water
Variability
Water Microbiology
Water Purification - methods
Water quality
water reuse
Water Supply - analysis
water treatment
Weather
Wildlife
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Summary:Microbial quality of reclaimed water can be adequately interpreted by graphical adjustment of experimental results to a lognormal probability distribution; the method serves to verify the degree of conformity to the proposed distribution and to visualize the time variability of the results. A conventional physico-chemical treatment can inactivate up to 1.0 microlog of common bacterial indicators, while maintaining time variability below 1.0 (microlog/100 ml). Dissolved organic matter in the influent will significantly alter the performance and the reliability of disinfection process, highlighting the need for improved adjustments of disinfectant dose to actual quality of treated water. Although those process may reach inactivation rates as high as 6.0 microlog for common bacterial indicators, their reliability may be considerably affected, forcing standard deviations beyond 3.0 (microlog/100 ml). Natural processes can provide inactivation rates from 3.0 to 3.5 for common microbial indicators, under the weather conditions studied. Although those values are lower than those of physical and chemical disinfectants, the reliability of natural processes is more stable, with standard deviations ranging from 0.65 to 1.1 (microlog/100 ml). Natural processes are particularly sensible to external inputs of microbial indicators, due to the presence of wildlife.
ISSN:0273-1223
1996-9732
DOI:10.2166/wst.2008.179