using flow cytometry to improve water quality · • all wtw and sr final water samples are...

Using flow cytometry to improvewater quality

Charmian Abbott15 May 2018

Copyright © United Utilities Water Limited 2016 2

United Utilities


Water Quality Data

15562 regulatory WTW coliform samples 2017

15561 zero results

1 infringement

Useful data to enhance water quality ?

Mean Zonal Compliance


So what does the data tell us?


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.


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.


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


So what does the data tell us?

Flow cytometry live cells and free chlorine


Flow cytometry as a leading indicator of performance


Inform operational decisions and risk assessments


Reducing challenge to the disinfection process


Proactive action


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


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


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 ?

using flow cytometry to improve water quality · • all wtw and sr final water samples are...

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