采用体积信息熵表征颗粒污泥系统稳定性及其稳定机制

SBR反应器中培养自养硝化颗粒污泥,在絮体转化为颗粒过程中,颗粒的体积信息熵从2.05(27 d,初见颗粒)降低为1.85(95 d),熵值降低的主要动力来自于松散的絮体在较快沉速选择压条件下被淘洗出系统.当絮体被淘洗出系统即完成颗粒化过程,在129 d时测得系统中颗粒沉速分布的中位数为6.27 m.h-1,因此颗粒体积熵值的变化不再受沉速选择压(6m.h-1)的控制.颗粒的粒径、沉速及体积熵值分布均呈现周期性变化,其中信息熵的均值为2.16,最小值为1.79,最大值为2.63.在这种周期性变化过程中,系统总是表现为粒径均值先增大后减小.熵值的波动的驱动力来自于颗粒的破碎与破碎体的成长,体积分布信息熵的大小可以很好地表征系统的稳定性及其稳定机制.

Index of Stability and Its Mechanisms of Aerobic Granular System Using Volume-based Information Entropy

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.