Upflow filter system

Figure 5. Cross section details of an upflow filter system.

A third type of reactor system is the upflow anaerobic sludge blanket (UASB) reactor system. The UASB is a continuous-flow system that maintains a dense flocculated biomass that is granular. The waste-water passes through this dense sludge blanket to achieve desired treatment efficiency. The UASB, anaerobic filter, and fluidized-bed systems have all been applied successfully to treat a variety of industrial waste streams. Table 22-44 summarizes some of the applications of these treatment technologies. 

This is the anaerobic equivalent of the trickling filter. It contains support media (rock, gravel, plastic) with a void space of 50% or more. The bulk of anaerobic bacteria grow attached to the filter medium, but some form floes that become trapped inside this medium. Wastewater upflow through the reactor helps retain suspended solids in the column. This system achieves a modest BOD removal, but a higher removal of solids. Approximately 20% of the BOD is converted to CH4. 

Common anaerobic bioreactor configurations are designed to obtain good mixing and biomass separation. This can be achieved by filtration, sedimentation and digestion before returning the clarified or treated liquid to the bioreactor use of anaerobic filters or upflow clarification or the use sequential reactors systems (Stephenson et al., 2002). Some of the most utilized anaerobic reactor configurations are briefly described below. 

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