Mohsen Nosrati - Department of Chemical Engineering, Biotechnology Group, Tarbiat Modarres University, P.B. ۱۴۱۱۵-۱۴۳, Tehran, Iran
Mehdi Jalali - Department of Chemical Engineering, Biotechnology Group, Tarbiat Modarres University, P.B. ۱۴۱۱۵-۱۴۳, Tehran, Iran
Shojaosadati - Department of Chemical Engineering, Biotechnology Group, Tarbiat Modarres University, P.B. ۱۴۱۱۵-۱۴۳, Tehran, Iran

Reaction constants and heat release during thermophilic aerobic digestion of typical secondary and mixed bio-solids (sludges) were determined. Maximum reaction constant occurred in the temperature range of 55-60 ºC. By the aid of a temperature P.L.C., measurement of heat releases were carried out. An amount equal to 16.2 KJ/g-cell was measured for secondary sludge digestion. Cell growth in mixed sludges provided an extra heat equal to 6.7 KJ/g-cell.

Bio-solids; Sludge; Thermophilic Aerobic Digestion; Kinetics; Heat Release