The stability mechanism of algal-bacterial granular sludge
LIU Yi1, ZHANG Bing1, SHI Wen-Xin1, ZHU Yi-chun2, LIU Zu-wen2
1. Key Laboratory of Three Gorges Reservoir Region's Eco-Environment, Ministry of Education, College of Environment and Ecology, Chongqing University, Chongqing 400045, China; 2. School of Civil and Surveying &Mapping Engineering, Jiangxi University of Science and Technology, Ganzhou 341000, China
Abstract：A stable algal-bacterial granular sludge (ABGS) system was established rapidly within 18 days by inoculating with aerobic granules and targeted algae (Chlorella and Scenedesmus) under non-aeration conditions. The results indicated that ABGS had higher biological activity, better nutrients removal performance, and higher mechanical strength than the conventional AGS, indicating the superior stability of ABGS. Moreover, the content of protein (PN) in extracellular polymeric substances (EPS), especially tightly bound layer EPS (TB-EPS), was found increasing significantly during the granulation. Specifically, the PN content of 114.4mg/g MLSS at the end of the operation was about 2.8 times higher than that of AGS. Further analysis of EPS components by three-dimensional fluorescence spectroscopy showed that amino acids, tryptophan, aromatic proteins, complex amino acids and tryptophan-like substances in TB-EPS were conducive to maintain the structural stability of granular sludge. In terms of microbial community structure, the ABGS had a higher microbial diversity and community richness than AGS. The enrichment of the prokaryotic Chloroflexi and Planctomycetes, and the eukaryotic Chlorophyta was beneficial to enhance the stability of the system.
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