Anglian water required a tertiary treatment solution for their site at Earls Colne in Essex. The discharge consents for the site were to be tightened by the Environment Agency. The site had no power available and the cost of introducing a power based tertiary treatment solution was prohibitive. The required improvements in the new discharge consent were focused on the solids and ammonia levels though some reduction in the BOD levels was also needed. The average flow through the works is 1,168 m3/d.