Influence of sulfuric acid concentration on biohydrogen production from rice mill wastewater using pure and coculture of Enterobacter aerogenes and Citrobacter freundii

We report a concise study on the influence of sulfuric acid concentration used in the hydrolysis of rice mill wastewater on biohydrogen production using pure as well as co-culture of Enterobacter aerogenes and Citrobacter freundii. A higher total reducing sugar release of 14.2 g/L was obtained with 1.5% sulfuric acid (v/v). The effect of pH on cumulative biohydrogen production from 1.5% acid hydrolyzed rice mill wastewater was investigated using pure and coculture of Enterobacter aerogenes and Citrobacter ferundii. The fermentative hydrogen production using mixed culture showed a maximum hydrogen yield of 1.61 mol/mol sugar. In addition, about 70% reduction in chemical oxygen demand (COD) and higher volatile fatty acids (VFA) production were observed. Modified Logistic, Gompertz and Richards models were used to fit cumulative hydrogen production data whereas Logistic equation was used fit growth data. Richards model showed best fit and Logistic equation gave least error in predicting maximum hydrogen producing potential.