The effects of organic carbon, ammoniacal-nitrogen, and oxygen partial pressure on the stratification of membrane-aerated biofilms

Timothy M LaPara, Alina C. Cole, John W. Shanahan, Michael J. Semmens

Research output: Contribution to journalArticlepeer-review

63 Scopus citations

Abstract

The purpose of this study was to examine the effects of different nutrient (carbon, nitrogen, oxygen) concentrations on the microbial activity and community structure in membrane-aerated biofilms (MABs). MABs were grown under well-defined conditions of fluid flow, substrate concentration, and membrane oxygen partial pressure. Biofilms were then removed and thin-sliced using a cryostat/microtome parallel to the membrane. Individual slices were analyzed for changes with depth in biomass density, respiratory activity, and the population densities of ammonia-oxidizing and denitrifying bacteria populations. Oxygen-sensing microelectrodes were used to determine the depth of oxygen penetration into each biofilm. Our results demonstrated that ammonia-oxidizing bacteria grow near the membrane, while denitrifying bacteria grow a substantial distance from the membrane. However, nitrifying and denitrifying bacteria did not grow simultaneously when organic concentrations became too high or ammonia concentrations became too low. In conclusion, membrane-aerated biofilms exhibit substantial stratification with respect to community structure and activity. A fundamental understanding of the factors that control this stratification will help optimize the performance of full-scale membrane-aerated biofilm reactors for wastewater treatment.

Original languageEnglish (US)
Pages (from-to)315-323
Number of pages9
JournalJournal of Industrial Microbiology and Biotechnology
Volume33
Issue number4
DOIs
StatePublished - Apr 1 2006

Keywords

  • Biofilms
  • Hybrid bioreactor
  • MABR
  • Membrane aeration
  • Nutrient removal

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