THE REDUCTION OF VOLATILE SOLIDS AND BIODEGRADATION KINETICS IN ONE-STAGE AUTOTHERMAL THERMOPHILIC AEROBIC DIGESTION FOR SEWAGE SLUDGE TREATMENT

In order to investigate the effects of operation parameters on the reduction of volatile solids (VS) and to propose biodegradation kinetics, batch and semi continuous experiments were carried out in a simulated one stage autothermal thermophilic aerobic digestion (ATAD) system. The suggested suitable variables are digestion temperature 55 degrees C, total solids (TS) concentration 5-6%, and hydraulic retention time 13-16 days. Primary, secondary, and mixture sludges have moderate impacts on VS reduction, and the ATAD digesters filled with three kinds of sludges may attain similar VS removal as their VS concentrations are within a similar level between 3.2 and 4.0%. VS is a suitable indicator for kinetics analysis. Three correction coefficients including digestion temperature (K-T), sludge concentration (K-1), and different kinds of sludges (K-2) are introduced to the first-order kinetics equation. The formulas for correction coefficients are K-T=0.012x1.024((T-20)), K-1=(52/TS)(1.6), K-2=1.0485 X (VS/TS)(0.11). The kinetics parameters derived from batch experiments are also suitable for semi continuous operation system.