Bioconversion of Sugarcane Vinasse into High-Added Value Products and Energy

Vinasse, a residue from bioethanol production containing high organic matter concentration, was used as substrate in submerged fermentation of Pseudomonas aeruginosa PA1 for biosurfactant production. About 2.7 g/L of rhamnolipids was obtained, with surface tension of 29.2 mN/m and critical micelle concentration of 80.3 mg/L. After separation of rhamnolipid and biomass, residual fermentation media were submitted to anaerobic biodegradation in mesophilic conditions. The residual medium derived from fermentation with vinasse diluted to 1 : 1, without addition of nitrogen, C : N 21, and for 168 h, led to 63.2% chemical oxygen demand (COD) removal and 97.6 mL CH₄/g COD_removed. Compared to results obtained with fresh vinasse (73.7% COD removal and 112.4 mL CH₄/g COD_removed), it could be concluded that both processes can be integrated in order to add value to the residue and obtain energy, reducing production costs and at the same time environmental impacts related to vinasse disposal.