Life-cycle costs - take your head out of the sand

摘要

Southern water Services' Millbrook WwTW at Southampton has three 2,400m~3 Mesophilic digesters, which are fed 24 hours a day with raw sludge, with a typical dry solids content (D/S) of between 6-8%. These are heated using spiral heat exchangers with a primary heat source of around 60℃. Pumps then recirculate sludge through the heat exchangers to maintain a constant heat within the digesters. This temperature should be maintained at 35℃ ± 1℃ for process requirements and must not fall below 32℃ to ensure HACCP compliance.