title: The shift of the microbial community in activated sludge with calcium treatment and its implication to sludge settleability.
abstract: The sludge settleability is of prime importance for the activated sludge process. The effect of calcium ion on the biological performance of sludge was investigated in a lab-scale activated sludge system with varying Ca(2+) concentration. Results indicated that addition of 150mg/L Ca(2+) to the influent significantly improved the settling characteristics and metabolic reactivity of activated sludge in the bioreactors. Analyses using denaturing gradient gel electrophoresis (DGGE) and 16S rRNA sequencing showed that a significant difference in the presence of certain bacterial groups between the sludge systems with 150mg/L Ca(2+) and those with 0-100mg/L Ca(2+) addition. Ca(2+) also increased the production of the extracellular polymeric substance (EPS) and facilitated the development of microbial cluster in the bioreactor. Study showed that an addition of 150mg/L Ca(2+) to the influent provides a simple approach to improve the settling properties of activated sludge and maintain high pollutant removal efficiency.
authors: Jiangsu Key Laboratory for Organic Waste Utilization, Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization, College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, China.
authors: Chengchen
authors: C
authors: Ye
authors: Jiangsu Key Laboratory for Organic Waste Utilization, Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization, College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, China. Electronic address: xpyang@njau.edu.cn.
authors: Xinping
authors: X
authors: Yang
authors: Jiangsu Key Laboratory for Organic Waste Utilization, Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization, College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, China; Rothamsted Research, Harpenden, Hertfordshire AL5 2JQ, UK.
authors: Fang-Jie
authors: FJ
authors: Zhao
authors: Jiangsu Key Laboratory for Organic Waste Utilization, Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization, College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, China.
authors: Lifei
authors: L
authors: Ren
mesh_terms: D001419:Bacteria / Q000187:drug effects* / Q000235:genetics; D019149:Bioreactors / Q000382:microbiology; D002118:Calcium / Q000494:pharmacology*; D016000:Cluster Analysis; D058645:Denaturing Gradient Gel Electrophoresis; D006863:Hydrogen-Ion Concentration; D010100:Oxygen / Q000032:analysis; D010802:Phylogeny; D011135:Polysaccharides, Bacterial / Q000378:metabolism; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D012722:Sewage / Q000382:microbiology*
chemical_list: D011135:Polysaccharides, Bacterial; D012336:RNA, Ribosomal, 16S; D012722:Sewage; D010100:Oxygen; D002118:Calcium
keywords: Activated sludge; Ca(2+); EPS; Microbial community; Settleability