Optimization of key factors affecting methane production from acidic effluent coming from the sugarcane juice hydrogen fermentation process

Response surface methodology with a central composite design was applied to optimize the key factors affecting methane production from the acidic effluent coming from the sugarcane juice hydrogen fermentation process. The parameters studied were substrate concentration, ratio of NaHCO₃ to substrate concentration and initial pH. The experimental results showed that substrate concentration and initial pH had significant individual (p < 0.05) effect on methane yield (MY). However, there was no interactive effect between these variables (p > 0.05). The maximum MY of 367 mL CH₄/g-volatile solid (VS)_added was obtained at the optimum conditions of 13,823 mg-COD/L, an NaHCO₃ to substrate concentration ratio of 3.09 and an initial pH of 7.07. Under the optimum conditions, MY was enhanced 4.4-fold in comparison to raw effluent.