The existing installed mixers at the Anglian Water-owned Cotton Valley Sewage Treatment Works (STW) were replaced with Sulzer submersible mixers type ABS XRW and now deliver significant energy savings. A trial and subsequent analysis showed that a reduction of the energy consumption by 38% could be achieved.
There were four aeration lanes with 12 fixed speed mixers operating 22 to 23 hours per day. Several mixers were not operating due to installation problems and mixer failure. The mixers were not energy efficient due to the fixed drives.
The Sulzer technical team surveyed the site and found that new shock absorbers and lifting handles needed to be provided for the new installation.