Abstract
The characteristics of solubilization of the excess sludge by hydrothermal reaction and the biodegradability of hydrothermally treated sludge were investigated and the parameters, which are needed for a simulation, was determined. The amount of reduction of sludge and the water quality of treated water were predicted in the simulation. And the simulation results were compared with the results of the continuous experiment. Consequently, the following results were obtained.(1) In order to determine operation conditions, depolymerizention does not have the necessity of taking into consideration and it is good to make solubilization into the index for deciding of operation conditions.(2) Parameters of the hydrothermally treated sludge obtained k2=2.5 (1/day), Ks2=1, 000 (mg/L), a2-=0.5 (mg/L), b =0.05 (1/day).(3) It was identified that excess sludge is reducible by an activated sludge process without excess sludge production using hydrothermal reaction process and that the amount of reduction of sludge can be correctly predicted by this research model.(4) It was suggested that the amount of reduct on of sludge by this process and the amount of solubilization of the excess sludge by hydrothermal reaction process are equal.(5) The water quality of treated water was indicated almost the same level as that of a conventional activated sludge process.
