Effects of Operating Pressure on Granular Sludge Flotation Mechanism Inside an Anaerobic Upflow Reactor

Abstract

This research utilized computational fluid dynamic simulations to evaluate the effect of the headspace pressure on the granular sludge flotation, using an operating anaerobic upflow reactor (AUR) at a cassava starch factory as the model reactor. Increasing the headspace pressure from to 56.68 kPa significantly reduced the average sludge volume fraction from .5424 to .493 at a reactor height of 1 m (α=.5). In addition, the liquid axial momentum was transformed to a radial form, the average liquid upflow velocity was significantly reduced from .17 to .11 m/s at a reactor height between 2 and 6 m, and the average liquid radial flow velocity increased from .62 s to .68 m/s at a reactor height between and 4 m (α=.5). An AUR with a low head pressure and a low liquid level encouraged granular sludge flotation.