Analysis of the factors that influence the aggregation-degree of microbial aggregates in sludge
影响微生物聚集体的聚集度的因素分析

A concept of sludge aggregation-degree is proposed, which includes two aspect definitions: one is the physical densification of sludge and the other is the aggregation of microbial species. Using bulking, flocculant and granular sludge as three typical aggregates and with reference to available bulking sludge control theories as well as the aerobic granulation conditions, the effects that influence the sludge aggregation-degree are discussed: ① a high level of substratc gradient, oxygen concentration and complex organic matter are beneficial for the increase of aggregation-degree; ② the effect of kinetic and diffusion limitation selections on aggregation-degree is controlled by the size of aggregates; and ③ the evaluation of storage capacity and its effect on aggregation-degree should take PHB, poly-P and glycogen into account. In addition, it is suggested that inhibition of the proliferation of filamentous bacteria is not necessary for control of sludge bulking, and based on the observation of granulation from filamentous sludge, controls of sludge bulking and increase of the aggregation-degree are similar. However, the aggregation-degree proposed in this paper is still immature and not quantitative,so further investigations are necessary.