Influence of recirculation rate on the performance of a combined anaerobic-aerobic reactor applied to the removal of carbon and nitrogen from poultry slaughterhouse wastewater

  • Carla L Lopes
  • Adriana N. de Lima Model
  • Jackeline T. Gotardo
  • Fernando H. Passig
  • Eloy L. de Mello
  • Benedito M. Gomes
  • Simone D. Gomes
Keywords: Anaerobic degradation, nitrification, denitrification, combined reactor.


The objective of this study was to evaluate a combined anaerobic-aerobic upflow fixed-bed reactor with liquid phase recirculation for the removal of nitrogen and organic matter from poultry slaughterhouse wastewater. The reactor performance was evaluated with a hydraulic retention time (HRT) of 11 h and three different recirculation rates (R=0.5; 1 and 2). The highest nitrogen removal efficiency value was obtained with an HRT of 11 h (6.8 h in the anaerobic zone and 4.2 h in the aerobic zone) and a recirculation rate of 2. In this condition, the total nitrogen removal efficiency was 69%,  with effluent concentrations of 6 mg NH4+ L-1 and 12 mg NO3- L-1. For all tested conditions, there was good chemical oxygen demand (COD) removal, with efficiency above 95%. The effect of dilution and the favoring of mass transfer caused by the increase in the recirculation rate positively influenced reactor performance.

Key words: Anaerobic degradation, nitrification, denitrification, combined reactor.


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eISSN: 1684-5315