Determination of Bio-Oxidation Energy Released by Thermophiles in Secondary and Mixed Bio-Solids

Reaction constants and heat release during thermophilic aerobic digestion of typical secondary and mixed sludges were determined. Maximum reaction constant, determined by measuring the amounts of biodegradable volatile suspended solids (bVSS) removed, occurred in the temperature range of ۵۵-۶۰ ºC. Measurement of heat releases were carried out, at the same range, by the aid of a temperature programmable logic controller (PLC). An amount equal to ۱۶.۲ KJ/g-cell was measured for secondary sludge digestion. The maximum amount of kinetic constant for secondary sludge (۰.۴۵ d –۱) was observed at temperature of ۵۵ ºC. Addition of primary sludge to secondary sludges decreased kinetic constants due to stimulate of biomass growth. Cell growth in mixed sludges provided an extra heat equal to ۶.۷ KJ/g-cell generated. However, it decreased the overall rate of heat release compared to the rate in the secondary sludge digestion.

کلیدواژه ها:

Biological waste treatment ، Heat release ، Thermophilic aerobic digestion ، Sludge