Flow diverted bed system for restroration of polluted stream water

초록

The flow diverted bed (FDB) system was developed to improve the stream water quality. This system (Cell 1) had two wetlands where the flow from the upper layer (aerobic) in the first wetland could be redirected to the lower layer (anaerobic) in the second wetland by the flow diverter, and vice versa. In addition, the yellow-soil media placed at the bottom layer allowed a larger influx in the lower layer and had a sorption capacity of phosphate ions. The removal efficiencies of COD, SS, TN and TP in Cell 1 [hydraulic loading rate (HLR) = 102.6±6.8 cm/d] with the diverter was 4.6-14.2 % higher than that in Cell 2 without the diverter. The values of void fraction, dimensionless variance, dispersion number and Peclet number for Cell 1 were found to be 0.7275, 0.2832, 0.1706 and 5.8617, respectively. The flow patterns were dominated by convection (plug flow) rather than dispersion (complete mix). Consequently, the flow diverter and yellow-soil media in this system played an important role in enhancing the treatability of pollutants and operating at a higher HLR.