Severn Trent begins rolling out new phosphorus removal technology

Thursday 27 April

Severn Trent is beginning to roll out new ground breaking technology to remove phosphorus from the sewage treatment process to meet new stringent targets.

The company has been trialling six new technologies at its site in Packington, Leicestershire, two of which are world firsts, to find the best way to reduce the amount of phosphorus from water that is returned to the environment.

Pete Vale, from Severn Trent, explains: “New legislation in the Water Framework Directive requires us to meet much tighter phosphorus limits than we have in the past and that’s why we’ve been trialling these new types of technology.

“We hope that by developing these we can get down to around the 0.1milligramme per litre level and greatly reduce the amount of phosphorus that goes back into our streams and rivers.”

Phosphorus is a normal part of domestic sewage but usual treatment processes only remove part of it.  

Pete continued: “During the trials we’ve been using some really state-of-the-art techniques to understand which technology will work for our sewage treatment sites that greatly differ in size – from very small local sites to one of the biggest in Europe.

“We’ve already taken some of the learnings and have installed some new technology at three plants with another nine in the planning process.

“This is just the beginning of the journey and we’ll be continuing this research to improve our phosphorous removing techniques and provide us with a more sustainable future.”

The technologies being evaluated are: membrane filtration; nano-particle embedded ion exchange; pile cloth media filtration; ballasted coagulation and clarification; immobilised algal bioreactor;  and absorption media reed beds.

The ion exchange and algal bioreactor, both of which were developed by Cranfield University, are being put into practical application for the first time.The pile cloth media filtration is now in place at three sites with plans for four more and the ballasted coagulation and clarification will be installed at two further sites in the near future.