Mixing in some savings

Achieving more than £37k per year of savings was a key benefit for Anglian Water following installation of two mixing systems for handling secondary sludge at Colchester sewage treatment works.

System Mix supplied STM (Small Tank Mixing) pumped mixing systems for secondary sludge tanks at the STW.

They replace four submersible mixers which were constantly failing. In addition to poor mixing, maintenance and safety issues had to be addressed each time the mixers needed to be lifted.

In January 2009 the site was using one 750kg bag of polymer per week, at a cost of £1455 per bag. By August 2009, a minimum of 50% was being saved in polymer use, one bag for every two weeks, with the potential for further savings if optimised for longer, giving a saving of £37,830/year minimum.

There has been a reduction in anti-foam chemical use, and the automated system has saved on man hours as operatives no longer have to spend 1 to 2h/day operating control valves.