Journal of Environmental Biology

Formation of aerobic granular sludge under adverse
conditions: Low DO and high ammonia

Sheng-Hua Zhang*, Xiao-Hu Zhang, Lu Lv, Qing Wang and Qipei Jiang  

Institute of Urban Environment, Chinese Academy of Sciences, Xiamen, 361021, China

*Corresponding Author email : shzhang@iue.ac.cn

Publication Data

Paper received:

22 October 2012

Revised received:

10 December 2012

Accepted:

15 December 2012

Abstract

In this study, two adverse environments: low dissolved oxygen (DO) and high ammonia concentration, were employed to investigate the morphology, interspecies quorum sensing, extracellular polymers (EPS) characterization and microbial communities in the formation of aerobic granular sludge. Results showed that low DO could promote filamentous bacterial outgrowth. Under high ammonia concentration aerobic granular sludge (AGS) could still be cultivated, although it was looser and lighter than the control group. During the early stage of the AGS cultivation process, AI-2 activity reached a peak value in all three reactors, and ultrasonic pre-treatment was not beneficial to the release of AI-2. During AGS formation, the production of polysaccharide exhibited increases from 12.2 % to 40.3 %, 49.6 %, and 29.3 %. And PS in R2 was the highest as the result of sludge bulking. PS/PN was 1.5~8 in the three reactors. Three-dimensional EEM fuorescence spectroscopy variation indicated the change of protein in EPS, and the highest intensity of Peak T1 was obtained. The location shift of Peak T1 was not obvious, and Peaks A, C, and T2 shifted toward longer wavelengths (red shift) of 5~60 nm, or shorter wavelengths (blue shift) of 10~25 nm on the emission scale and / or excitation scale in all three reactors. This provided spectral information on the chemical structure changes. Bacteria in R3 had the highest species diversity, and all bacteria in b-Proteobacteria were identified as genus Thauera, which suggested that simultaneous nitrification and denitrification occurred in R3. The filamentous bacteria in seed sludge and R2 were species-richer. There was a low abundance of filamentous bacteria in R1 and R3, which contributed to the granule structure stability.

Key words

 Aerobic granular sludge, Low dissolved oxygen, High ammonia concentration, Interspecies quorum sensing, Microbial communities

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