Performance of flocs and biofilms in integrated fixed-film activated sludge (IFAS) systems for the treatment of oil sands process-affected water (OSPW)

Chunkai Huang, Yijing Shi, Mohamed Gamal El-Din, Yang Liu

Research output: Contribution to journalArticlepeer-review

30 Scopus citations


This study evaluated the roles of suspended flocs and attached biofilms from integrated fixed-film activated sludge (IFAS) systems in their overall contribution toward organic compound removal in oil sands process-affected water (OSPW). The batch experiments were operated with suspended flocs and biofilm carriers from our continuous laboratory-scale IFAS reactors for the OSPW treatment. A distinct difference between IFAS flocs and biofilms for the chemical oxygen demand (COD), ammonium and acid extractable fraction (AEF) removal was demonstrated. Compared to the biofilms, the flocs demonstrated considerably higher removal rates for COD and ammonium, whereas, biofilms had better performance on the AEF removal than flocs. Meanwhile, the results also revealed that the biodegradation was the principal removal mechanism whereas, the biosorption contributed little to the OSPW organic compounds and the ammonium removals in the IFAS system. Microbial analysis from q-PCR revealed that the abundances of nitrifiers and denitrifiers genes were significantly higher in flocs than in biofilms in both raw and ozonated-OSPW IFAS reactors. The microbial communities analysis from MiSeq sequencing showed that Proteobacteria, Acidobacteria, Nitrospirae and Bacteroidetes were dominant phyla in both flocs and biofilms.

Original languageEnglish (US)
Pages (from-to)368-377
Number of pages10
JournalChemical Engineering Journal
StatePublished - 2017

Bibliographical note

Funding Information:
This research was supported by a research grant from Napier-Reid Ltd., Shell Canada Limited, Helmholtz-Alberta Initiative (HAI), and the Natural Sciences and Engineering Research Council of Canada (NSERC). This research was also supported by an NSERC Industrial Research Chair (IRC) Program in Oil Sands Tailings Water Treatment through the support by Syncrude Canada Ltd., Suncor Energy Inc., Shell Canada, Canadian Natural Resources Ltd., Total E&P Canada Ltd., EPCOR Water Services, IOWC Technologies Inc., Alberta Innovates – Energy and Environment Solution, and Alberta Environment and Parks.

Publisher Copyright:
© 2016 Elsevier B.V.


  • Biofilms
  • Flocs
  • Illumina high-throughput sequencing
  • Integrated fixed-film activated sludge (IFAS)
  • Oil sands process-affected water (OSPW)


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