Anoxic phosphorous uptake in circulating fluidized bed bioreactor

A. Patel, G. Nakhla, J. Zhu

Research output: Contribution to conferencePaperpeer-review

1 Citation (Scopus)


In this study, biological phosphorous removal in circulating fluidized bed bioreactor (CFBBR) using real municipal wastewater as feed with two entirely separate aerobic and anoxic beds was investigated. With an average influent total phosphorous concentration of 4.6 mg/L, the system achieved average effluent total phosphorous concentration of 1.4 mg/L, translating into 70% total phosphorous removal at a total hydraulic retention time (HRT) of 2.0 hours over a temperature range of 20 °C to 25 °C. P concentration in the biomass was determined at 4 - 5 % of volatile suspended solids (by wt). In addition, the system consistently achieved effluent TSS, BOD5, NH4-N, and NO3-N concentrations of <10, <, 1, and 4-6 mg/l respectively. This phosphorous removal was achieved without recirculation of bioparticles between anoxic and aerobic beds. The presence of phosphorous accumulating organisms (PAOs) and denitrifying phosphorous accumulating organisms (DPAOs) was confirmed by carrying out various batch tests on attached and detached biomass from anoxic and aerobic bed. The tests confirmed P uptake under anoxic condition in the presence of nitrate. Phosphorous release was observed only after nitrates dropped to <1 mg/L. Under anaerobic conditions, 0.16 mg of PO4-P was released per mg of COD consumed on an average, whereas after addition of nitrates, P uptake was 0.31 mg PO4-P per mg of NO3-N consumed on an average. The detachment rate coefficients (bs) of PAOs in aerobic and anoxic biofilm were 0.1-0.11 d -1, and 0.17-0.19 d-1, respectively.

Original languageEnglish
Publication statusPublished - 2005
Externally publishedYes
Event33rd CSCE Annual Conference 2005 - Toronto, ON, Canada
Duration: 2 Jun 20054 Jun 2005


Conference33rd CSCE Annual Conference 2005
CityToronto, ON

ASJC Scopus subject areas

  • General Engineering


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