UASB granular sludge plants

These systems have been successfully used for decades for pretreatment of wastewater containing high concentrations of readily biodegradable compounds such as sugars, alcohols, starches (breweries, fruit processing, beverage production alcoholic beverages, potato processing, paper industry).

Because larger organic loading factors can be applied than in aerobic processes, there are smaller reactor volumes and also energy is produced as biogas.

Among granular sludge plants, the most widely used is the UASB (Upflow Anaerobic Sludge Blanket) system. It is based on the creation of a dense sludge bed at the bottom of the reactor, in which all biological degradation reactions take place. The key feature of this system is that microbial aggregation occurs in a structure called a granule that has excellent sedimentation characteristics within the reactor itself. Thus, there is no need to immobilize the complex microbial consortium on a substrate.

Effluent from a UASB reactor requires aerobic post-treatment for removal of residual organic matter, nutrients (nitrogen and phosphorus) and, if present, pathogens.