A novel liquid-solid circulating fluidized-bed bioreactor for biological nutrient removal from municipal wastewater

Nabin Chowdhury, Jesse Zhu, George Nakhla, Ajay Patel, Mohammad Islam

Research output: Journal PublicationArticlepeer-review

30 Citations (Scopus)


Biological nutrient removal (BNR) using a novel liquid-solid circulating fluidized-bed (LSCFB) bioreactor was assessed with and without particle recirculation. The LSCFB employs attached microbial films for the biodegradation of both organics and nutrients within a single circulating fluidized-bed unit. This new technology combines the more compact and efficient fixed-film process with the BNR process that provides the additional removal of nitrogen and phosphorous. A lab-scale LSCFB was demonstrated to treat degritted municipal wastewater (MWW), operated at an empty-bed contact time of 0.82 h. The system removed 94, 80 and 65 % of organic (chemical oxygen demand, COD), nitrogen (N), and phosphorous (P), respectively, without particle recirculation, whereas with particle recirculation the system removed excess phosphorus and achieved overall removal efficiencies of 91, 78 and 85 % for C, N, and P, respectively. The system generated effluent characterized by <5 mg biological oxygen demand/L, <5 mg total suspended solids/L, <1 mg NH4-N/L, <7 mg total nitrogen/L, and <1 mg PO4-P/L. Combination of nitrification, denitrification and enhanced biological phosphorus removal in one unit saves space, reduces energy consumption, and also produces less sludge at approximately 0.12-0.13 g volatile suspended solids/g COD consumed. Excellent lab-scale results led to the establishment of a pilot-scale LSCFB for MWWtreatment at a capacity of 5000 L/day. Initial results of the pilot-study showed a similar trend in BNR as observed in the lab-study.

Original languageEnglish
Pages (from-to)364-372
Number of pages9
JournalChemical Engineering and Technology
Issue number3
Publication statusPublished - 2009
Externally publishedYes


  • Biofilm
  • Biological phosphorus removal
  • Biomass
  • Denitrification
  • Liquid-solid circulating fluidized bed
  • Nitrification

ASJC Scopus subject areas

  • General Chemistry
  • General Chemical Engineering
  • Industrial and Manufacturing Engineering


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