A study on the improvement of sludge dewaterability by thermal conditioning

The paper reviews the research progress in sludge dewaterability by thermal conditioning and analyzes the fundamental mechanisms of sludge dewaterability. The main factors affecting sludge dewaterability by thermal conditioning are experimentally investigated. The results show that the major factors for improving sludge dewaterability by thermal conditioning are conditioning temperature and residence time. It is found that the optimal temperature and residence time are 180°C and 60mins, respectively. The moisture content of sludge cake is 50.88% after pressure filtration for 50 minutes. Thermal conditioning transforms organic compounds of sludge into soluble substances and greatly increases the COD of the separated water. After thermal conditioning at 180°C, the COD of the separated water is about 420 times of the original sludge. Pulse-flash sludge dewatering has the advantage of low energy consumption and can help us achieve the goals of sludge reduction, harmlessness and efficient utilization. Therefore, thermal conditioning of sludge, especially pulse-flash sludge dewatering technology, has a potential for wide engineering applications in the future.