Abstract
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.
Highlights
Effluents from animal processing industries, such as slaughterhouses, after anaerobic processing have been used in many biological nitrogen removal studies in view of their eutrophic potential and the risks to aquatic life and human health due to the presence of nitrogen
The use of industrial effluents as carbon sources for denitrification is an important strategy (Bernet et al, 1996; Mees et al, 2013). This requirement for an organic carbon source enables the use of endogenous electron donors from the anaerobic digestion, such as volatile organic acids, methane, ammonia or reduced sulfur compounds (Foresti et al, 2006), which are made possible in continuous systems
There was an increase in alkalinity due to ammonification and a conversion of chemical oxygen demand (COD) to volatile organic acids, which led to sufficient system buffering capacity
Summary
Effluents from animal processing industries, such as slaughterhouses, after anaerobic processing have been used in many biological nitrogen removal studies in view of their eutrophic potential and the risks to aquatic life and human health due to the presence of nitrogen This requirement for an organic carbon source enables the use of endogenous electron donors from the anaerobic digestion, such as volatile organic acids, methane, ammonia or reduced sulfur compounds (Foresti et al, 2006), which are made possible in continuous systems
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