High-rate Denitrification of Reject Water from a Sludge Treatment Process

초록

Two types of bench-scale expriments using upflow biofilm reactors packed with granular floating polystyrenes(GFPs) or polyurethane foam cubes (PFCs), were conducted to investigate the denitrification performance of reject water. An additional experiment using upflow sludge blanket (USB) was also conducted for comparison in performance. As the results, a very high denitrification rate was acquired in both upfolw biofilm reactors because the highly concentrated the two biofiltrations, the denitrification rate using GFP was 3.5 kg-1/Nm-3 d-1, and higher than that using PFC. The amount of total attached biomass and solids capture capacity were also greater in GFP than in PFC. Moreover, the back -washing of the GFP packed column was very easily conducted with air and water agition. In USB, about 0.5-1.0 mm of biogranules were grown in the reactor, however the granules were fragile compared to those of upflow anaerobic sludge blanket (UASB) for methane fermantation. In USB, it was difficult to maintain a stable granule concentration in the reactor, and the volumetric denirification rate was also lower than biofilm reactor using GFP. Conclusively, of the processes investigated in this study, upflow biofilm reactor using GFP was the most acceptable process for reject water treatment in the aspect of both treatability and operaion.