Factors Affecting the Design and Performance of Upflow Anaerobic Filters

Anaerobic filters have been used for almost twenty years to treat a variety of industrial wastes, yet until recently little was known about the factors affecting their design and performance. Tests with laboratory and full-scale plants operated under a variety of conditions have identified hydraulic retention time as the most important design and performance parameter. Influent waste strength and reactor height have essentially no effect on treatment efficiency when operating at a given hydraulic retention time. Media specific surface area and the orientation of the media seem to have a minor effect on performance but the benefit generally is not sufficient to justify increasing the specific surface area beyond about 100 m 2 /m 3 . Effluent recycle provides only a small improvement in treatment efficiency but may be beneficial to reduce the need for adding chemicals for pH control. A performance model is presented that can be used for obtaining approximate reactor sizes.