In the operation of biological wastewater treatment processes, fast sludge settling during liquid-solids disengagement is preferred as it affects effluent quality, treatment efficiency and plant operation economy. An important property of fast settling biological sludge is the ability to spontaneously form big and dense flocs (flocculation) that readily separates from water. Therefore, there had been much research to study the conditions that promote biological sludge flocculation. However, reported findings have often been inconsistent and this has possibly been due to the complex nature of the biological flocculation process. Thus, it has been challenging for wastewater treatment plant operators to extract practical information from the literature. The aim of this review is to summarize the current state of understanding of the factors that affect sludge flocculation so that evaluation of such information can be facilitated and strategize for intervention in the sludge flocculation and deflocculation process.

在生物废水处理过程的操作中，液固分离过程中的快速污泥沉降是优选的，因为它会影响废水质量，处理效率和工厂运营经济性。快速沉淀生物污泥的一个重要特性是能够自发形成大而致密的絮凝物（絮凝物），该絮凝物容易与水分离。因此，已经进行了很多研究来研究促进生物污泥絮凝的条件。但是，报告的发现常常不一致，这可能是由于生物絮凝过程的复杂性所致。因此，对于废水处理厂的操作者来说，从文献中提取实用信息是一项挑战。