Cultivation of aerobic granules in a sequential batch shaking reactor

Aerobic granular sludge is a promising biotechnology for wastewater treatment system. In this report, aerobic granular sludge was successfully cultivated in a sequential batch shaking reactor in which horizontal circular flow could be formed by shaking. In this way, granulation and aeration could be simultaneously achieved. In comparison with sequential batch airlift reactor, more homogeneous circular flow was formed in the sequential batch shaking reactor. The aerobic granules obtained in the reactor were smooth, 1.2 mm in average diameter, and had a settling velocity of 50-52 m h(-1). In addition, an increase in the hydrophobicity of the cell surface of granules indicated that granulation could be related to the change in cell hydrophobicity. Finally, microbial observation showed that rod-shape and coccoid bacteria were the dominant species in mature granules. Results of this study have important implications on the mechanism of the granulation process and further practical application.