title: Biofilm formation and microbial community analysis of the simulated river bioreactor for contaminated source water remediation.
abstract: OBJECTIVE
  The start-up pattern of biofilm remediation system affects the biofilm characteristics and operating performances. The objective of this study was to evaluate the performances of the contaminated source water remediation systems with different start-up patterns in view of the pollutants removal performances and microbial community succession.
  
  
  METHODS
  The operating performances of four lab-scale simulated river biofilm reactors were examined which employed different start-up methods (natural enrichment and artificial enhancement via discharging sediment with influent velocity gradient increase) and different bio-fillers (Elastic filler and AquaMats® ecobase). At the same time, the microbial communities of the bioreactors in different phases were analyzed by polymerase chain reaction, denaturing gradient gel electrophoresis, and sequencing.
  
  
  CONCLUSIONS
  The pollutants removal performances became stable in the four reactors after 2 months' operation, with ammonia nitrogen and permanganate index (COD(Mn)) removal efficiencies of 84.41-94.21% and 69.66-76.60%, respectively. The biomass of mature biofilm was higher in the bioreactors by artificial enhancement than that by natural enrichment. Microbial community analysis indicated that elastic filler could enrich mature biofilm faster than AquaMats®. The heterotrophic bacteria diversity of biofilm decreased by artificial enhancement, which favored the ammonia-oxidizing bacteria (AOB) developing on the bio-fillers. Furthermore, Nitrosomonas- and Nitrosospira-like AOB coexisted in the biofilm, and Pseudomonas sp., Sphaerotilus sp., Janthinobacterium sp., Corynebacterium aurimucosum were dominant in the oligotrophic niche.
  
  
  CONCLUSIONS
  Artificial enhancement via the combination of sediment discharging and influent velocity gradient increasing could enhance the biofilm formation and autotrophic AOB enrichment in oligotrophic niche.
authors: Department of Environmental Engineering, Zhejiang University, Hangzhou, People's Republic of China.
authors: Xiang-Yang
authors: XY
authors: Xu
authors: Li-Juan
authors: LJ
authors: Feng
authors: Liang
authors: L
authors: Zhu
authors: Jing
authors: J
authors: Xu
authors: Wei
authors: W
authors: Ding
authors: Han-Ying
authors: HY
authors: Qi
mesh_terms: D001419:Bacteria / Q000235:genetics / Q000378:metabolism*; D018441:Biofilms; D057919:Biological Oxygen Demand Analysis; D018533:Biomass; D019149:Bioreactors / Q000382:microbiology*; D003352:Corynebacterium / Q000235:genetics / Q000378:metabolism; D052918:Environmental Restoration and Remediation / Q000379:methods*; D009606:Nitrosomonas / Q000235:genetics / Q000378:metabolism; D011549:Pseudomonas / Q000235:genetics / Q000378:metabolism; D012336:RNA, Ribosomal, 16S; D045483:Rivers; D042744:Sphaerotilus / Q000235:genetics / Q000378:metabolism; D014876:Water Pollution
chemical_list: D012336:RNA, Ribosomal, 16S