Continuous acidogenesis of sucrose, raffinose and vinasse using mineral kissiris as promoter

Abstract

The use of kissiris as promoter (culture immobilization carrier) in anaerobic acidogenesis of sucrose, raffinose and vinasse is reported. Initially, the effect of pH (4-8) and fermentation temperature (18-52 °C) on the accumulation of low molecular weight organic acids (OAs) during sucrose acidogenesis, was evaluated. The promoting effect of kissiris was confirmed compared to free cells, resulting in 80% increased OAs production. The optimum conditions (pH 8; 37 °C) were used during acidogenesis of sucrose/raffinose mixtures. A continuous system was also operated for more than 2 months. When sucrose and sucrose/raffinose mixtures were used, lactic acid type fermentation prevailed, while when vinasse was used, butyric acid type fermentation occurred. Total OAs concentrations were more than 14 g/L and ethanol concentrations were 0.5-1 mL/L. Culture adaptation in vinasse was necessary to avoid poor results. The proposed process is promising for new generation ester-based biofuel production from industrial wastes.

Keywords: Acidogenesis; Biofuel; Raffinose; Sucrose; Vinasse.