Characteristic of granular sludge bed and granular sludge in interior diversion expanded granular sludge bed

The interior diversion expanded granular sludge bed was concurrently operated for 140d to study the characteristic of the granular sludge bed. The influent COD concentration varied from 2000mg/L to 22300 mg/L, hydraulic retention time was maintained constant at 24 h and the organic loading rate was changed through a change in substrate concentration. The results showed that the reactor had great COD removal efficiency. When the MLSS was 23.1g/L, the influent COD was 18890mg/L, the COD removal efficiency was 80.4%; The interior diversion EGSB could greatly improve the role of gas-dynamic, when the liquid upflow velocity was 3.55m/h, the gas production was 5.96 L/d shows higher sludge bed expansion rate than 2.77 L/d about 9.5%. During the experimental, the anaerobic sludge has the following properties: the average sludge diameter was increased from 0.41mm to 1.66mm. Observed under the scanning electronic microscopy, we found that the sludge appeared obviously granulation, the bacteria amount and species are more than seed sludge after operation of 50d. It was found that rough surface of anaerobic sludge has clear figure with being covered by mucous lamina, with visible hole or cavity on surface.