Uprating of Mogden Sewage Treatment Works

Mogden Sewage Treatment Works treats a population equivalent of approximately 1.8 m people from a catchment area of 160 sq. kilometres in North and West London. Substantial improvements have been undertaken over recent years including the automation of the works and major process improvements providing new sludge thickening facilities. In order to satisfy new obligations on treatment capacity set by the EC Urban Wastewater Treatment Directive a series of trials evaluating innovative and novel alternatives to conventional design were conducted. The “Mogden Trials” as they became known were granted a £1m research budget from the Thames Water capital release committee, however, substantial cost savings from an original capital control cost of £85m (NPV £141m) were considered possible. This paper describes how the savings were achieved through the trials and the assessment of options and provides details on the process of uprating the treatment plant including the successful partnering agreement between the owner/operator Thames Water and the US based company Black and Veatch.