Abstract
The management of excess sludge in wastewater treatment accounts for a major portion of the cost for wastewater treatment and entails significant technical challenges. Swim-bed technology containing an innovation attached-growth material named biofringe (BF) allows the retention of large amounts of biomass, which could contribute to the reduction of excess sludge production. The treatment performances of a lab-scale reactor packed with BF material under various operational conditions and volumetric loading rates were investigated. The process demonstrated effective treatment of high-strength wastewater. COD removal efficiencies greater than 80% were consistently achieved even with volumetric loading rates as high as 7 kg-COD/m3/d. Observed sludge yields (Yobs) from 0.13 kg-MLSS/kg-CODremoved to 0.29 kg-MLSS/kg-CODremoved were obtained in swim-bed wastewater treatment. The occurrence of an abundance of protozoa and mentozoa in the activated sludge floc could account for this significantly low production of excess sludge. The long sludge retention time (SRT) was also regarded to be another reason for the low excess sludge production. The attachment of large amounts of biomass on the BF material might be due to the extremely high ratios of extracellular polymers (EPS) to biomass, which varied from 64% to 84%.
