MODELING OF SETTLING CHARACTERISTICS OF SBR

Abstract

The sludge setting plays a very important role on the operation of sequential batch reactors (SBR). Generally SBRs are operated at optimum concentration of MLSS in 3000-5000 mg/L range. However, in case of unfavorable condition, it would be necessary to operate the same SBR for higher MLSS (5000-8000 mg/L) concentration. It is well known that higher MLSS operation reduces the settling speed of the sludge. It can cause washout of sludge during decantation in SBR. For safe operation of SBR, the sludge interface level should be lower than the decant level of the weir of decanter. Hence, in order to simulate the settling characteristics of actual operating SBR, set of settling tests were conducted on concentrated SBR sludge. Cylinders of various configurations (l-L, 2-L) and beaker (4-L) were taken for study. The results of the test were used to identify the most common Vesilind sludge settling parameters V0 and k. These two parameters were used to develop the settling model for the actual SBR for various operating MLSS concentration. The result shows that although the models favorably predict the actual behavior of settling on the qualitative basis but it may differ significantly in a quantitative basis. However, all of the present studies adjust the settling characteristics or purpose another approaches for the estimation of settling characteristics of sludge