An effective way to select slow-growing nitrifying bacteria by providing a dynamic environment

Abstract

In this study, two laboratory scale sequencing batch reactors (SBRs) were conducted to study the stability of aerobic granules. The strategy was involved in stepwise increase in ammonium (NH4+-N) concentration in the influent. Results showed that the activity of nitrifying bacteria and diameter of the aerobic granules significantly increased with gradually increasing NH4+-N, which reached persistently new balances by homeostasis. As a result, the stability of aerobic granules was remarkably enhanced. The value of sludge volume index (SVI) was below 25 ml/g, the mean settling velocity was excellent up to 107 m/h. The NH4+-N removal efficiency averaged above 99% and total nitrogen (TN) removal was greatly enhanced and could reach 68%. Besides dissolved oxygen, the granules size was also a dominant factor to influence denitrification, which could gradually increase in variable conditions through homeostasis. Stable, dense and well-settling nitrifying granules can be developed for simultaneous nitrification and denitrification removal.

Effects of temperature on simultaneous nitrification and denitrification via nitrite in a sequencing batch biofilm reactor

“…The nitrate generated is then denitrified via nitrite in the presence of an organic carbon source to nitrogen gas (N 2 ). In conventional wastewater treatment processes within continuous flow systems [1,2] or sequencing batch systems [3][4][5][6], denitrification can be placed either before nitrification or after nitrification. Both pre-denitrification and post-denitrification have disadvantages [7].…”

Coupling physical selection with biological selection for the startup of a pilot-scale, continuous flow, aerobic granular sludge reactor without treatment interruption

“…6 . The slow-growing microorganisms were reported to facilitate the formation of granules ( Liu et al., 2004 ; Xia et al., 2007 ). Since the SRTs of dense granules and bioflocs were not able to be differentially controlled in previous granulation studies in SBRs, especially during the reactor startup, the SRT was usually not considered as a decisive factor for aerobic granulation ( Li et al., 2008 ).…”