[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.