Abstract
Biofringe (BF) carrier material creates swimming motion due to velocity of downflow wastewater, a characteristic of swim-bed technology, and provides a high degree of substrate-biomass contact. In this study, BF fiber material was packed in a plug-flow activated sludge reactor, to investigate its feasibility in improving the sludge settleability and enhancing the pollutant degradation performance of the activated sludge process. High SBOD5, SCOD, and ammonium removal efficiencies of 99.1%, 96.5% and 83.6%, respectively were obtained at volumetric loading rate of 4.5 kg–SCOD/m3/d. SVI values below 50 ml/g and high settling velocities demonstrated satisfactory settling characteristics of the biomass, which were attributed to the increase in the size of the biomass flocs as a result of use of BF carrier material. Relatively low viscosity of mixed liquor also facilitated sludge settling performance as no sludge bulking problems were encountered throughout the experimental period. Existence of a large amount of protozoa and metazoa observed through microscopic examination was considered to contribute to the low sludge yield compared to conventional activated sludge. Microbial analysis demonstrated microbial community shift between the seed sludge and the sludge sample after 378 days of operation with proteobacteria to be predominant. The results demonstrated that use of swim-bed technology enhanced treatment performance and provided process stability to the conventional activated sludge process.
