Swim-bed Technology as an Innovative Attached-growth Process for High-rate Wastewater Treatment

Abstract

Swim-bed technology using the novel acryl-fiber biomass carrier--biofringe (BF) attachment material--demonstrated effective treatment of high-strength organic wastewater with 80% COD removal efficiencies at high volumetric loadings up to 12kg/m3/d with a hydraulic retention time of 3 h. BF material allowed for attachment of large amounts of biomass in a matrix that flexes with the wastewater flow, thus providing a high degree of contaminant-biomass contact in a fully retainable biofilm. As much as 133 g of biomass per meter of BF was retained for an equivalent 13.3 g/l with respect to the BF retention or reaction zone. Limited evidence for nitrification occurred only at low COD loading rates (ca.1.6 kg/m3/d) . In addition, filamentous biomass growth was very heavy at the lower loading rates, but was avoidable at COD loadings of 8kg/m3/d or greater. The levels of extracellular polymers--proteins in particular--in the biofilm were very high compared to levels reported for flocculent or granular sludges. While treatment in this study focused on industrial level applications, the possibility of using this technology in other treatment scenarios involving lower organic loadings was discussed.