rình tự hàng loạt lò phản ứng (SBR) có thể ảnh hưởng đến hạt hiếu khí. Chương này trông vào thông số khác hoạt động SBR, thời gian chu kỳ và ảnh hưởng của nó đối với hạt hiếu khí, cũng như trên các đặc tính của hạt hiếu khí. Thời gian chu kỳ có liên quan với tần số rửa trôi của SBR, có thể được coi là một loại thủy lực áp lực chọn lọc. Trong thực tế, lựa chọn áp lực thủy lực đã được chứng minh là quan trọng cho sự hình thành của hạt kỵ khí trong một SBR kỵ. | 3 Aerobic Granulation at Different SBR Cycle Times Zhi-Wu Wang and Yu Liu CONTENTS Effect of Cycle Time on Aerobic Effect of Cycle Time on Properties of Aerobic INTRODUCTION It appears from the preceding chapters that a number of operating parameters of a sequencing batch reactor SBR can influence aerobic granulation. This chapter looks into another SBR operating parameter cycle time and its effect on aerobic granulation as well as on the characteristics of aerobic granules. Cycle time is associated with the washout frequency of SBR which can be regarded as a kind of hydraulic selection pressure. In fact hydraulic selection pressure has been shown to be important for the formation of anaerobic granules in an anaerobic SBR Hulshoff Pol et al. 1982 Shizas and Bagley 2002 . Definitely a sound understanding of the role of SBR cycle time in aerobic granulation would be helpful for the optimization and design of large-scale aerobic granular sludge SBR. EFFECT OF CYCLE TIME ON AEROBIC GRANULATION Tay Yang and Liu 2002 investigated the formation of nitrifying granules at different cycles times of 3 to 24 hours in SBRs. A complete washout of the sludge occurred and led to a failure of nitrifying granulation in the SBR run at the shortest cycle time of 3 hours while only typical bioflocs were cultivated in SBR operated at the longest cycle time of 24 hours figure . After 2 weeks of operation tiny nitrifying granules with mean diameters of and mm appeared in SBRs run at the cycle times of 12 and 6 hours respectively. In comparison with the seed sludge that had a very loose and irregular structure nitrifying granules developed showed a compact structure with a clear outer shape moreover the nitrifying granules formed at the cycle time of 6 hours were found to be smoother and denser than those developed at a cycle time of 12 hours figures and c . 37 2008 by Taylor
