Water treatment and pathogen control: Process efficiency in achieving safe drinking water
By Mark W LeChevallier and Kwok-Keung Au
Increasingly, microbial issues are commanding the attention of water treatment operators, regulators, and the media. There are many treatment options to eliminate pathogenic microbes from drinking water. Finding the right solution for a particular supply requires sifting through a range of sometimes competing processes.
Processes for removal of microbes from water include pretreatment, coagulation/ flocculation/sedimentation, and filtration. Pretreatment processes include application of roughing filters, microstrainers, off-stream storage, or bank infiltration, each with a particular function and water quality benefit. Filtration can be accomplished using granular media filters, slow sand, precoat filters, membranes, or other filters. Oxidants may be added to water for a variety of purposes, including control of taste and odor compounds, removal of iron and manganese, Zebra Mussel control, and particle removal, among others.
For control of microbes within the distribution system, disinfectants must interact with bacteria growing in pipeline biofilms. Models for removal of particles and microbes by granular media filtration, and equations for predicting microbial inactivation by disinfectants, can aid in the understanding and prediction of the effectiveness of treatment processes for microbial pathogens.
Water Treatment and Pathogen Control is intended to provide a critical analysis of the literature on removal and inactivation of pathogenic microbes in water to aid the water quality specialist and design engineer in making important decisions regarding microbial water quality.
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Contents, foreword, acknowledgements, acronyms and abbreviations
2. Removal processes
3. Inactivation (disinfection) processes
4. Performance models
5. Treatment variability
6. Process control
7. Reference list
Publishing and ordering information
© World Health Organization (WHO) 2004
Published on behalf of WHO by IWA Publishing
ISBN 92 4 156255 2 (WHO); ISBN 1 84339 069 8 (IWA Publishing)
Order No. 11500563
Rolling revision of the Guidelines for Drinking-water Quality
Water treatment and pathogen control is included in the plan of work of the rolling revision of the WHO Guidelines for Drinking-water Quality.
The Guidelines for Drinking-water Quality Final Task Force meeting (Geneva, 2003) noted that finalization and progressive updating of the supporting document Water Treatment and Pathogen Control: Process Efficiency in Achieving Safe Drinking-water would provide substantiation and support to other supporting documents dealing with the issue of system safety evaluation.
The document, which has been in preparation for several years, includes a selective and succinct review of the literature, focusing on high-quality papers. The key papers included are those that address failure mode and suboptimal performance. The document will require an update, because this is a dynamic and active area of continued new information. New data should go into a future revision/edition of the document.
Second edition of supporting document, publication date around 2008.
Progress to date
The Guidelines for Drinking-water Quality Working Group meeting (Geneva, 2005) agreed on a plan of work for the preparation of a second edition.