THERMAL HYDROLYSIS PRE-TREATMENT TO DEWATER ABILITY OF MECHANICAL DEWATERED SLUDGE
Municipal and industrial wastewater treatment plants produce large amount of sludge. The mechanical dewatered sludge still has a water content of 80 wt％ and a thermal drying step is needed to meet further disposal requirement with large energy consumption. Thermal hydrolysis pre-treatment can improve the dewater ability of mechanically dewatered sludge, which changes the combination of water and solid in sludge cake, causing the water trapped in cell released. There is no water evaporation during the whole process. The energy consumption of thermal hydrolysis is less compared with thermal drying process. A high-pressure (300℃, 25MPa) reactor was used for thermal hydrolysis of mechanical dewatered sludge. Hydrolysis temperature was set at 90℃, 120℃, 150℃, 180℃and 210℃ respectively with a heating time of 30min. Thermal hydrolyzed sludges were dewatered by centrifugal sedimentation and pressure filtration. The dissolution rate of organic components in thermal hydrolyzed sludge was analyzed. Thermal hydrolysis improved the dewater ability of mechanical dewatered sludge as organic solids hydrolysis changed sludge structure and caused water trapped in bacteria cells released. N hydrolyzed (45.2％,180℃) more easily than C and H. According to centrifugal settling results, the optimal hydrolysis temperature was 180℃.The water content fell to 1.44kg/kg DS at 180℃ under RCF of 9000g. Pressure filtration results showed that water content in sludge cake was only 0.5kg/kg DS with hydrolysis at 180℃, which could be seen as the upper limits of any conventional mechanical dewatering device.
mechanically dewatered sludge thermal hydrolysis dewater ability
HONGLEI. MA HAOHUI. XIE YONG. CHI JIANHUA YAN MINGJAIN NI
State Key Laboratory of Clean Energy Utilization, Zhejiang University ,Hangzhou, China
国际会议
北京
英文
400-405
2010-05-17（万方平台首次上网日期，不代表论文的发表时间）