Severn Trent Water has begun trialling new water treatment technologies to reduce phosphorus from its sewage treatment works, in order to meet the requirements of the Water Framework Directive.
The water company is evaluating six technologies – two of which are world firsts – at its Packington sewage treatment works in Leicestershire.
The new stricter rules in the Water Framework Directive limit the amount of phosphorus allowed at sewage treatment works to 0.5 milligrammes per litre or, in some cases, as low as 0.2mg/l.
Severn Trent said existing UK technologies are unlikely to be capable of meeting the new limits, meaning the firm will have to upgrade around 100 works – many of which are being upgraded to reduce phosphorus for the first time.
Phosphorus is required by all living organisms for cell growth. It is a non-renewable resource, non-substitutable for food production, essential for agriculture and directly linked to food security.
Domestic sewage contains phosphorus, and standard sewage treatment processes will only provide a low-level of phosphorus removal.
The six technologies Severn Trent is evaluating are: pile cloth media filtration; membrane filtration; ballasted coagulation; nano-particle embedded ion exchange; immobilised algal bioreactor; and absorption media reed beds.
Severn Trent technical lead for innovation Pete Vale said: “Two of the technologies – the ion exchange, and the algal bioreactor – have been developed specially by Cranfield University and put into practical application for the first time.
“It’s relatively early days but we’ve seen some encouraging results from all of the technologies which is heartening given that some of them are genuine world first designs.
“Each of the technologies have their advantages, and their disadvantages, which is why we’re running the trials.
“And the right solution for a large sewage treatment works might not be the same for a small sewage treatment works but, by looking at six such innovative solutions, we’re not only putting ourselves at the forefront of the phosphorus issue in the UK, we’re also making sure we’re making the right decision for our customers.”
