Áp lực lựa chọn về vận tốc chất lỏng upflow đã được chứng minh là một lực lượng lái xe của hạt kỵ khí trong chăn upflow bùn kỵ khí (UASB) lò phản ứng (Pol Hulshoff, Heijnekamp, và Lettinga 1988; Alphenaar, Visser, Lettinga 1993). Mặc dù hạt hiếu khí là nghiên cứu rộng rãi trong SBRs, nó là chưa rõ ràng làm thế nào các hạt phát triển hiếu khí được hình thành trong SBR. các tính năng chính của một SBR cột là chu kỳ hoạt động kế tiếp của nó, và mỗi chu kỳ bao gồm làm đầy, thông khí, giải quyết, và xả | 4 Aerobic Granulation at Different Settling Times Lei Qin and Yu Liu CONTENTS Effect of Settling Time on the Formation of Aerobic Effect of Settling Time on the Settleability of Effect of Settling Time on Cell Surface Effect of Settling Time on Production of Extracellular Effect of Settling Time on Microbial Activity of Aerobic Accumulation of Polyvalent Cations in Aerobic Effect of Shift of Settling Time on Aerobic Effect of Settling Time on Microbial Rationale Behind Settling Time-Initiated Aerobic INTRODUCTION The selection pressure in terms of upflow liquid velocity has been demonstrated to be a driving force of anaerobic granulation in upflow anaerobic sludge blanket UASB reactors Hulshoff Pol Heijnekamp and Lettinga 1988 Alphenaar Visser and Lettinga 1993 . Although aerobic granulation is now studied extensively in SBRs it is not yet clear how the aerobically grown granules are formed in SBR. The main feature of a column SBR is its successive cycle operation and each cycle consists of filling aeration settling and discharging. At the end of each cycle settling of biomass takes place before effluent is withdrawn and sludge that cannot settle down within a given settling time is washed out of the reactor together with effluent through a fixed discharge port. As aerobic granules are much denser than suspended flocs they require less time to settle than flocs do. It appears that in SBR the settling time is likely to exert a selection pressure on the sludge particles that is only particles that can settle down below the discharge point within the given settling time are retained in the reactor otherwise they are discharged. This chapter aims to offer in-depth insights into the role of settling time in aerobic granulation in SBR. Such information
