using flow cytometry to improve water quality · • all wtw and sr final water samples are...
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Using flow cytometry to improvewater quality
Charmian Abbott15 May 2018
Copyright © United Utilities Water Limited 2016 2
United Utilities
Copyright © United Utilities Water Limited 2016 3
Water Quality Data
15562 regulatory WTW coliform samples 2017
15561 zero results
1 infringement
Useful data to enhance water quality ?
Mean Zonal Compliance
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So what does the data tell us?
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Flow Cytometry
Overview of the timeline since introduction
• Feb 2014 - First cytometer (C6) commissioned (FC1)Initial testing on target samples, small stability trial carried out.
• July 2015 - Second cytometer (C6) commissioned (FC2)Introduced to provide more capacity for analysis of all WTW and SR monitoring points.
• July 2017 - Third cytometer (FACSVia) commissioned (FC3)Introduced over the C6+ solely to enable on site repair/servicing.
For development/validation work – but C6 issues are delaying this.
• Apr 2018 - Fourth cytometer (FACSVia) expected to replace FC1 or FC2This will bring more resilience to the lab, aid future validation exercises, and release a C6 to the Ops/Process scientists.
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Flow Cytometry• Two stains – SYBR Green and Propidium Iodide
• Intact cells take up the fluorescent stain SYBR® green
• This stain binds to DNA and RNA and fluoresces at
530 nm
• Propidium iodide can only enter cells with damaged
membranes
• PI also binds to DNA and RNA but fluoresces at 690
nm
• By using a mixture of the stains intact and damaged
cells can be identified
• Report Intact, Dead and Total cell counts plus %
dead cell counts to the business.
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Flow cytometry at United Utilities
• In place since late 2014
• All WTW and SR final water samples are automatically analysed for flow cytometry alongside
routine regulatory analysis and available on corporate systems
• Any abnormal results are automatically highlighted and notification sent to the water quality
analysts for review, dissemination and action
• Flow Cytometry data is trended and feeds into:
• Weekly reports for all sites distributed to the Director of Water and his wider team
• Tier meetings for process and network which feed into our DWSP risk assessments
• Reviews following abnormal results or infringements/events
• Reactive risk assessments providing provisional view of water quality in emergency situations
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So what does the data tell us?
Flow cytometry live cells and free chlorine
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Flow cytometry as a leading indicator of performance
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Inform operational decisions and risk assessments
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Reducing challenge to the disinfection process
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Proactive action
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Flow cytometry challenges
• Understanding what the data is saying: what is abnormal and when to respond?
• In our experience, earlier models were not very reliable, needed to be sent away for repair and
reproducibility of results was low.
• Forming baseline and fingerprint for each water supply system
• Understanding the impact of different treatment processes: e.g not as insightful for sites with UV
treatment
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Flow Cytometry - Advantages• Highly sensitive
• Live cell numbers much greater than shown by
colony counts
• Fast (same day results)
• Small sample volumes required (we use 50µl)
• Versatile (protocols available for many types of
analysis in clinical and industrial fields)
• Allows simultaneous quantitative assessment
of multiple cellular parameters at the single-cell
level
• Shows similar rates of removal to that of particle
counting (> 99.6%)
• Provides another tool to proactively investigate
and improve treatment performance
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Using flow cytometry to enhance water quality:
• Raw water source risk• Particularly borehole sources
• Process optimisation including assessment of disinfection efficiency• Leading indicator, early warning• Understanding the challenge to the disinfection process from upstream processes• Bacteriological infringement investigations
• Assessment of risk to inform Drinking Water Safety Plan• Potential identification of ingress• Identification of bacterial regrowth• Potential indicator of water age and/or taste and odour • Early indication of microbiological quality of the water following mains repair/intrusive work
• Potential for use as a field instrument ?
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