The Effects of Different Mechanical Turning Regimes on Heat Changes and Evaporation During Sewage Sludge Biodrying

Abstract

Biodrying can be improved by understanding the changes in heat and moisture with different turning regimes. The aim was to investigate the drying effect of turning and to optimize the turning regime. Control technology based on in situ temperature and vapor sensors was applied. Turning in the temperature-increasing phase was the least effective strategy. Turning once in the later stage of the first thermophilic phase and twice after the first thermophilic phase produced the highest bioheat (1.641 MJ kg⁻¹ initial biodrying material), achieved the highest evaporation (0.379 kg kg⁻¹ initial biodrying material), and achieved a 58.1% heat utilization rate.

Keywords:

• Heat loss
• Heat production
• Mechanical turning
• Sewage sludge biodrying
• Water evaporation