Optimization of Biohydrogen Production (BHP) from Agro Waste Water (Cassava Waste Water): A Case of Box-Behnken Response Surface Methodology (RSM)

Abstract

This work aims at optimization of biohydrogen production(BHP) from agro waste water. To determine the physicochemical properties of the cassava waste water the sample was subjected to analysis using standard methods. Broth medium was made and substrate preparation was carried out, inoculum pretreatment was carried out and the medium was cultivated following standard method. To optimize the process condition, three-factor-three-variables response surface methodology (RSM) was used; these gave 17 experimental runs and were carried out. Results showed that the physicochemical analysis of agro waste water had initial pH of 5.46 which indicated a low acidity, total diffuse solid of 3.93 mg/L, chemical oxygen demand of 0.25 mg/L and biochemical oxygen demand of 0.16 mg/L. The highest biohydrogen yield(BHY) obtained was 4.25 mlat a coded factors of X1= 0, X2=1 and X3= 1, but the RSM statistical software predicted BHY of 4.009 ml at X1= -1, X2= -1.0 and X3= -0.011 at desirability of 0.706. This was validated by carrying out three experiments which gave an average BHY of 4.00 ml. The coefficient of determination (R2) of 0.9966% implies most variability can be explained by regression model. The experimental findings concluded that the use of RSM with appropriate experimental design can help in achieving the optimum yield of biohydrogen, which could serve as an alternative source of energy that could replace petroleum-based fuels.