A comparative study of UASB and anaerobic fixed film reactors with development of sludge granulation

This study was conducted to compare the operating characteristics of laboratory UASB and fixed film reactors with various wastes: complex carbohydrate vs simple volatile waste, and concentrated vs diluted wastes. The sludge granulation was influenced more by the characteristics of the waste used than by the reactor type itself. Microscopic observations, including SEM, revealed that microbial compositions in the two reactors were essentially identical. Complex carbohydrate waste, having a higher COD/VA ratio, produced filamentous microbes and these appeared to promote granulation. With the development of granulation, the applicable organic loading rates were increased for both reactors. The fixed film reactor generally had a consistent treatment capability with various waste.