[Impact of hydraulic retention time (HRT) in ABR on its operation performance and granular sludge characteristics when treating low-strength wastewater].

The impact of hydraulic retention time (HRT) in an anaerobic baffled reactor (ABR) on its operation performance and granular sludge characteristics was investigated through both testing its operation and analyzing the particle size distribution (PSD) and fractal dimensions of these sludge granules when treating low-strength wastewater. As HRT was gradually reduced from 24 h to 5 h, ABR had good performance on the organics removal and could reach about 90% for the COD removal, the VFA contents in ABR effluent and their pH values showed opposite trends. Most COD in wastewater was removed in the first two compartments of ABR during the running period of HRT from 24 h to 12 h, after that, the middle three compartments in ABR performed the most removal work.

[Fractal structure and physicochemical characteristics analysis of aerobic sludge floc in A2/O process].

Image analysis method, free settling test were performed to determine the morphology, particle size distribution, free setting velocity, effective density, porosity and fractal dimensions in different topological spaces of aerobic sludge flocs in A2/O process. Then the physicochemical indices, corresponding to the sludge properties such as: settleability, compressibility, dewaterability and stability, were measured. Besides these, the extra-cellular polymeric substances (EPS) were extracted from sludge and classified as different components.