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Description: Raising the bar on disinfectant residuals
Raising the bar on disinfectant residuals
Maintaining a disinfectant residual — whether using chlorine, chloramine, or other chemicals —is an important part of providing protection against microbial contamination of water systems. However, there are wide-ranging opinions on what disinfectant residual concentration is needed and the best approaches to meet those requirements. One approach to obtaining a more complete picture of what is occurring is to run a calibrated hydraulic/water quality model of the system. A hydraulic model can be viewed as a “digital twin” of the real system. A digital twin behaves like the real system, but can also fill in values where samples aren’t available and can predict what will happen in the future or with a different operation. A combination of modeling and sampling can identify locations and times when maintaining an adequate residual will be problematic.
Author(s)
Tom Walski
SourceArticle from July/ Aug 2019 World Water Magazine
Project IDWW36
SubjectModeling;Disinfection;Distribution
Document typeMagazine article
PublisherWater Environment Federation
Print publication date Sep 2019
ISSN1354-313X
Volume / Issue42 / 4
Content sourceWorld Water Magazine
First / last page(s)34 - 35
Copyright2019
Word count1,857
Subject keywordsdigital twinwater qualitydisinfectant residualsBentleyWaterGEMShydraulic modeling

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Description: Raising the bar on disinfectant residuals
Understanding the problem
Raising the bar on disinfectant residuals
Disinfectant residual concentrations are not steady or uniform. They vary over time and location. In some locations, it is easy to maintain an acceptable residual value, while in others it may be virtually impossible without considerable expense. Sampling in the system provides only a partial picture of what is occurring in the pipes. The concentration may be different a half-mile away or an hour...
PublisherWater Environment Federation
Copyright2019
Word count250
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Description: Raising the bar on disinfectant residuals
Potential solutions
Raising the bar on disinfectant residuals
Numerous measures can be taken to increase disinfectant residuals – each with its own advantages and disadvantages: Some are summarized below:
PublisherWater Environment Federation
Copyright2019
Word count618
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Description: Raising the bar on disinfectant residuals
Selecting a solution
Raising the bar on disinfectant residuals
It is clear, there is no one-size-fits-all solution for low residuals. The best alternative will depend on local conditions, such as decay rate, size of the system, extent of the problem, and the water system’s preference for incurring additional capital, labor, treatment, or chemical costs.
PublisherWater Environment Federation
Copyright2019
Word count415
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Description: Raising the bar on disinfectant residuals
Ancillary issues
Raising the bar on disinfectant residuals
Several complicating factors increase the need and value of a digital twin model.
PublisherWater Environment Federation
Copyright2019
Word count290
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Description: Raising the bar on disinfectant residuals
Future considerations
Raising the bar on disinfectant residuals
As disinfectant residual concentration regulations evolve, it may become more difficult to comply with new standards. There are numerous steps that can be taken to address this issue and the use of a hydraulic/water quality model – a digital twin – can be very effective in comparing alternatives in order to determine what option would be the most effective for the system under study.
PublisherWater Environment Federation
Copyright2019
Word count64
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Description: Raising the bar on disinfectant residuals
Author’s Note
Raising the bar on disinfectant residuals
With more than 40 years of experience in water and wastewater system design and operation, Tom Walski is a Bentley Fellow at Bentley Systems, Inc., located in Exton, Pennsylvania, United States.
PublisherWater Environment Federation
Copyright2019
Word count33
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Raising the bar on disinfectant residuals