城市污水污泥微波热水解特性研究

在80～170 ℃进行1～30 min的城市污水污泥微波热水解,微波频率2 450 MHz,最大输出功率1 kW,考察挥发性悬浮固体(VSS)和悬浮固体(SS)溶解率,污泥上清液COD和TOC浓度、污泥粒径、形态变化和碳氢氮含量等污泥热水解特征,分析污泥离心脱水性能的改善和减量化效果.结果表明,微波加热使污泥有机物水解反应快速发生,水解过程受温度影响显著.热水解5 min时,150℃和170℃的VSS溶解率为15.8%和29.4%;10 min时COD溶解率达到19.07%和25.75%,COD和TOC浓度在170℃分别为9 860.0 mg/L和2 949.70 mg/L.超过5～10 min,VSS和COD水解率增加缓慢.通过扫描电镜(SEM)观察到污泥热水解后菌体细胞破裂.与碳和氢相比,污泥中氮的水解率更高,170℃微波热水解5 min氮的水解率达到67%.150℃和170℃热水解10 min离心脱水污泥含水率降低到73.1%和65.5%,脱水性能改善,相应减量化率为33.9%和51.7%.

Sewage Sludge Microwave Thermal Hydrolysis Process

Sewage sludge thermal hydrolysis experiments with 2,450 MHz microwave energy were carried out under 80-170 degrees C with 1-30 min. Max. microwave output power was 1 kW. Volatile suspended solid (VSS) dissolving ratio, COD dissolving ratio, liquor COD and TOC, sludge particle size distribution, micro-structure, and elements (C, H and N) hydrolysis were measured. Also, sludge dewaterability improvement was inspected. Results show that microwave heating leads fast sludge hydrolysis reaction. Temperature was the controlling process factor. Under 150 degrees C and 170 degrees C with 5 min, 15.8% and 29.4% VSS dissolved respectively. While, with 10 min 19.07% and 25.75% COD moved to liquor. Release of organic materials increased liquid sludge COD and TOC concentration. Under 170 degrees C with 10 min, COD and TOC concentration were 9,860.0 mg/L and 2,949.70 mg/L respectively. More than 5 to 10 min, VSS and COD dissolving trend turned slow down. SEM test showed cell disruption of hydrolyzed sludge. N could dissolve more easily than C and H. 67% N hydrolysiszed under 170 degrees C with 5 min. Bacterial cell disruption and organic solid hydrolysis improved sludge dewaterability. Sludge cake moisture content decreased from 82% to 73.1% and 65.5% under 150 degrees C, 170 degrees C with 10 min microwave hydrolysis. Accordingly, sludge amount reduction ratios were 33.9% and 51.7% respectively.