Insights into function of hydrocyclone separator and modified volcanic rock coagulant on formation of aerobic granular sludge

Abstract

Hydrocyclone separator and novel coagulants were adopted to separately enhance the granulating process of aerobic granular sludge. For hydrocyclone separator, although there was no obvious large particle, it was feasible to improve the sludge sedimentation capacity, indicated by the sludge volume index. Moreover, the nitrogen removal performance was promoted by the separator with a nitrogen removal rate of 8.2 mg/(LÁh), nearly two times of system without a separator. Meanwhile, nitrogen-related microbial communities were stimulated, for example, Thauera and Nitrosomonas. Another method of coagulation by the modified volcanic rock promoted the sludge settling performance. The optimum coagulating conditions were the coagulant size of 100 μm with dosage of 6 g/L. The addition of polyacrylamide played a weak role in granulation. Overall, the role of hydrocyclone separator and modified volcanic rock coagulant belonged to the improvement of the settleability of sludge and the aggregation of sludge, respectively.