The influence of the sodium bicarbonate (NaHCO3) on the performance of an anaerobic sequencing batch biofilm reactor treating vinasse at 55 and 35ºC was evaluated. The reactor was filled with polyurethane foam and agitated at 300 rpm. The acclimatization period at 55ºC lasted 50 days, and the reactor was fed with vinasse (COD from 0.3 to 1.0 g/L). A previous enrichment of methanogenic population was provided for the reactor operated at 35ºC, feeding it with an ethanol based substrate (2.5 gCOD/L) during 21 days. Further on, organic loading rates (OLR) ranging from 0.85 to 5.70 gCOD/L.d were applied to the reactor at 55ºC, supplemented with 1.2 to 0.4 gHCO3-/gCOD. At 35ºC the reactor was subjected to OLR ranging from 2.85 to 36.0 gCOD/L.d with 0.4 to 0.2 gHCO3-/gCOD. COD removal ranged from 43 to 78% at 55ºC and from 75 to 85% at 35ºC. Alkalinity supplementation was found to be essential for process stability, but the amount required was lower at 35ºC.
anaerobic process; thermophilic; mesophilic; alkalinity; NaHCO3
