[Fractal characteristics of mature aerobic granular sludge cultivated by different carbon sources]

In order to characterize the dense and regular level of aerobic granular sludge (AGS) which was cultivated by different carbon sources, the SEM images of mature AGS were used in the study. The calculation process using Photoshop and Fips2 on fractal characteristics of these granules was built. The lowest box-counting dimension was bulking aerobic granular sludge cultivated by glucose (No. 1), which was 1.794 +/- 0.011; the box-counting dimension of AGS cultivated by peptone (No. 3) and domestic sewage (No. 5) were reached up to 1.866 +/- 0.018 and 1.880 +/- 0.015. The boundary box-counting dimension of the AGS was also calculated and the average value was 1.14. The AGS cultivated by beer (No. 6) was more regular in shape and the boundary box-counting dimension was 1.115 +/- 0.003. The AGS cultivated by landfill leachate (No. 7) was the most irregular in shape. This study indicates that fractal dimension provides an approach for quantification of dense and regular level of AGS, furthermore, it could be used to characterize the status of AGS, such as bulking.