A comprehensive study on autothermal thermophilic aerobic digestion process of waste activated sludge in a continuous stirred digester
by Lobat Taghavi; Teimour Amani; Mohsen Nosrati
International Journal of Environment and Waste Management (IJEWM), Vol. 15, No. 2, 2015

Abstract: In this research autothermal thermophilic aerobic digestion (ATAD) of a typical waste activated sludge (WAS) was investigated in a continuous stirred digester, precisely. Volatile solids (VS) reduction, energy audit, pathogen inactivation and sludge dewaterability during aerobic digestion were studied. Two processes with air and pure oxygen sparging were performed and their results were compared. In a continuous ATAD system working with WAS, feeds concentrated preliminary more than 30 g/L can provide stable temperatures above 40°C in aerobic digester. Similarly, sludge feeds concentrated initially above 20 g/L can provide stable temperatures above 43°C in an oxygen sparged aerobic digester. Sludge feeds with total solids concentrations of 60 and 10 g/L demonstrated the highest (57°C) and the lowest (24°C) reactor temperature, respectively. Feed sludges having thickest concentrations of 60 and 50 g/L which caused the thermophilic temperatures of 57°C and 51°C in the reactor, provided moderately dewaterable sludges. In oxygen sparged process, evaporation heat loss was reduced and temperature profiles were higher and also, pathogen removal was sensibly improved in compared with air sparged system.

Online publication date: Sat, 09-May-2015

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