Comparison of pretreatment strategies of sugarcane baggase: Experimental design for citric acid production

Solid state fermentation was carried out to compare efficiency of acid, alkaline and urea pretreatment of sugarcane bagasse for production of citric acid using Aspergillus niger ATCC 9142. Plackett–Burman statistical design was used to evaluate significance of variables. Pretreatment of bagasse by urea was known as the most influential treatment to increase citric acid production (137.6 g/kg of dry sugarcane bagasse and citric acid yield of 96% based on sugar consumed). Finally, up scaling was achieved to a 20 L solid state fermentor in which humidity was constant in gas phase and urea-treated sugarcane bagasse. The produced acid concentration and yield in fermentor was 82.38 g/kg of dry substrate and 26.45 g/kg day, respectively.