Water Intelligence Online © IWA Publishing 2002

Sludge Treatment Options: Aerobic digestion

E.I. Stentiford: [School of Civil Engineering, University of Leeds, UK]

Aerobic digestion has been used to treat a wide range of sludges, generally at a relatively low solids concentration. The process basically consists of aerating sludge in open basins and involves the direct oxidation of any biodegradable matter with the production of new cellular material and subsequent oxidation of some of this material. An increasing emphasis on the need to reduce pathogens has changed current thinking such that the majority of plants now being constructed are designed to operate thermophilically. At these elevated temperatures, in the 45–65 °C range, it is easier to ensure adequate removal of potential pathogens. In order to minimize operating costs these systems have significantly lower heat losses than earlier plants. In addition, an increasing number of these plants operate autothermically by ensuring that a sufficiently thickened feed sludge is used and close control of the heat balance is maintained. Bearing in mind that in most sludge processing plants a principal requirement is for pathogen control, this chapter mainly concentrates on thermophilic aerobic digestion, particularly the autothermal aerobic digestion process (ATAD).

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UNIQUE ID: 200202011

[Taken from the book 'Sludge into Biosolids: Processing, Disposal, Utilization' ©2002 IWA Publishing ISBN: 1 900222 08 6]