Thermophilic anaerobic digestion of raw sugarcane vinasse

Highlights

Anaerobic digestion of vinasse was evaluated during a sugarcane harvesting season.

Single and two-stage systems were used for sugarcane vinasse treatment.

A methane yield of 306 NmL-CH4.g-CODremoved was achieved with the two-stage system.

The energy yield increased by 25.7% using two-stage anaerobic digestion.

Effluent propionate concentrations was independent of OLR increase.

Abstract

The application of thermophilic anaerobic digestion is a logical choice for the treatment of sugarcane vinasse (industrial wastewater from ethanol production) because this process enables the recovery of energy as hydrogen and methane without requiring energy for heat or interfering in its quality as a bio-fertilizer. Thus, this study evaluated the performance of thermophilic methanogenic up-flow sludge blanket reactors (UASB) operating continuously in single-stage (UASB I) and two-stage (UASB II) systems vinasse during the sugarcane harvesting season (180 days). The maximum methane yields were 250.9 NmL-CH4.g−1CODremoved and 316.0 NmL-CH4.g−1CODremoved for UASB I and II, respectively, corresponding to 71.7% and 90.3% of the maximum theoretical methane yield (350 NmL-CH4.g−1CODremoved). Furthermore, the energy production from the two-stage system was 25.7% higher than the single-stage system, indicating the need for an acidogenic phase to improve both the removal of organic matter and energy extraction from sugarcane vinasse.

Keywords

  • Anaerobic digestion;
  • Up-flow sludge blanket reactor (UASB);
  • Single-stage system;
  • Two-stage system;
  • Raw sugarcane vinasse

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