Abstract |
Several porous biomass-support systems are currently available for use in the activated-sludge process. One of these systems, Captor, utilizes polyurethane foam pads to provide biofilm growth sites that transform an aerobic suspended-growth reactor into a fixed-film reactor. In a two-year pilot-plant evaluation, three reactors were operated under various loading conditions, dissolved-oxygen levels, and pad-cleaning frequencies in both series and parallel flow configurations. The system efficiently converted soluble biochemical oxygen demand to new biomass, but the majority of the solids exited in the process effluent rather than via the pad cleaners. Increased pad cleaning provided only marginal improvement. Nitrification was evaluated during series operation. Pad durability was good, but overall system economics were not impressive. There was no evidence of enhanced oxygen transfer efficiencies as previously claimed. (Copyright (c) ASCE 1988.) |