School of Engineering


Cara Wray

Microbial Communities across Water Treatment Plants: Fate of Coliforms and other Bacteria

  • STREAM PhD Cohort VI
  • Start Date: October 2014
  • End Date: November 2019
  • Research Area: Environment
  • Supervisors: Prof David Graham, Dr David Werner, Severn Trent

Cara was awarded her EngD in the Summer of 2020.

I am investigating the relationship between chlorine disinfection and bacteria in water treatment plants. The water industry uses coliform bacteria as an indicator. They detect faecal contamination and organisms potentially harmful to human health.
They are an important group of bacteria to monitor. They have the greatest capacity for causing illness in humans. They will cause repercussions for the water company if they are not removed by the treatment process.
Chlorine is the most widely used method of water disinfection globally as it is both cheap and effective.
I am investigating how coliforms could survive chlorine disinfection in water treatment plants. This can occur through a variety of processes, including:
  • genetic resistance
  • shielding by particles
  • shielding within biofilms
Bacteria that develop resistance to chlorine could compromise water quality. This puts the public at risk of infection with microbial contaminants.
Chlorine resistance could also be a reason why water treatment plants detect coliforms in their final water. This is despite the plant working to satisfactory standards.
My academic background is in microbiology and molecular biology. I graduated from the University of Birmingham with a BSc in Human Biology. My final year project focused on antibiotic resistance plasmids in E.coli.
The project developed my interest in microbiology and resistance mechanisms. This led me to undertake an MSc in Clinical Microbiology at the University of Nottingham. After graduating in 2013, I worked as a microbiology quality analyst for Severn Trent.
My work involved analysing drinking water samples for coliforms and other indictor organisms. It also developed my interest in the microbiology of water treatment processes.
The STREAM program was the perfect opportunity to combine my academic interest in resistance with the more practical concerns of the water industry.
A huge benefit of STREAM is that it allows you to consider problems and questions from different viewpoints. You gain advice and experience from both academia and industry.

Current Status

Senior Advisor, Public Health and Standards Team at Severn Trent Water.

Cara Wray, PhD student with STREAM, School of Engineering, Newcastle University