Simulation of water removal process and optimization of aeration strategy in sewage sludge composting

Reducing moisture in sewage sludge is one of the main goals of sewage sludge composting and biodrying. A mathematical model was used to simulate the performance of water removal under different aeration strategies. Additionally, the correlations between temperature, moisture content (MC), volatile solids (VS), oxygen content (OC), and ambient air temperature and aeration strategies were predicted. The mathematical model was verified based on coefficients of correlation between the measured and predicted results of over 0.80 for OC, MC, and VS, and 0.72 for temperature. The results of the simulation showed that water reduction was enhanced when the average aeration rate (AR) increased to 15.37 m3 min−1 (6/34 min/min, AR: 102.46 m3 min−1), above which no further increase was observed. Furthermore, more water was removed under a higher on/off time of 7/33 (min/min, AR: 87.34 m3 min−1), and when ambient air temperature was higher.