2006 Volume 42 Issue 3 Pages 139-149
The use of a biomass carrier is preferred for the cultivation of slowly growing anammox sludge. In this study, PVA gel was selected as a biomass carrier for anammox sludge and applied in a fluidized-bed reactor (FBR). A recycle pump was used to induce a flow rate of 6 － 7 l/min to maintain fluidized bed conditions. Both influent NH4-N and NO2-N concentrations were increased stepwise to 300 mg N/l. With hydraulic retention times (HRTs) from 16 h to 9 h in phase 1, NH4-N and NO2-N removal efficiencies were about 81% and 92%, respectively. With HRTs from 9 h to 4 h in phase 2, NH4-N removal efficiency was 77% and NO2-N removal efficiency was 89%. The removal rates of ammonium and total nitrogen in phase 1 increased up to 0.71 and 1.35 kg N/m3/d, respectively. Maximum removal rates of ammonium and total nitrogen in phase 2 increased quickly up to 1.5 and 3.0 kg N/m3/d, respectively. Ratios of T-N removal, NO2-N removal, and NO3-N production to NH4-N removal during phase 1 were 1.91:1.12:0.22. These ratios during phase 2 were 1.96:1.18:0.21. The color of the PVA-gel beads changed from white to brownish red, which is consistant with anammox bacteria. By the Denaturing Gradient Gel Electrophoresis (DGGE) method, both KSU-1 and KU-2 anammox strains were detected with KSU-1 in dominance in the FBR process.
