Initialization, enhancement and mechanisms of aerobic granulation in wastewater treatment

Aerobic granulation is a promising technology that has increasingly attracted global attention due to its potential as a cost effective system, and its application in a wide range of wastewaters. Aerobic granules are highly structured suspended microbial aggregates capable of degrading biodegradable compounds with excellent settling properties, good pollutant removal and high resistance to toxic compounds. However, evidences show that granules formation in high strength wastewaters takes relatively much longer time at initial stages. This article reviews the state-of-the-art of the researches done on the factors influencing granulation at initial stage, with particular focus on the aggregation of microbial cells. In addition, this review discusses the effective approaches adopted for the enhancement of initial development of aerobic granules. Moreover, the current article highlights the mechanism of aerobic granulation at its initial stage, as well as other different approaches. Finally, future research directions to improve aerobic granules formation at the initial stage are discussed