Index of Stability and Its Mechanisms of Aerobic Granular System Using Volume-based Information Entropy
采用体积信息熵表征颗粒污泥系统稳定性及其稳定机制

Autotrophic nitrification granular sludge was cultivated in a sequencing batch reactor (SBR), the information entropy of volume distribution decreased from 2.05 (27 d, granules were firstly observed) to 1.85 (95 d) during granulation period. And the driving force for the decrease of information entropy could be ascribed to the washing out of flocs by means of the hydraulic selection pressure. After the granules formation stage finished, the median settling velocity of the granules system was 6.27 m·h-1 and the information entropy of volume distribution would not be controlled by the settling velocity selection pressure (6 m·h-1). It was found that the size, settling velocity and the volume-based information entropy periodically changed. The mean, minimum and maximum of information entropy were 2.16, 1.79 and 2.63, respectively, during the period from 122 d to 579 d. The mean size varied by the pattern of increase and decrease periodically. The driving force for the fluctuation of the information entropy was the smashing of the larger granular and the volume fragmentation growth, and the volume distribution of the information entropy could well indicate the stability of granular sludge systems.