UTILIZATION OF BOX-WILSON EXPERIMENTAL DESIGN MATRIX IN BIOGAS PRODUCTION: A RESPONSE SURFACE APPROACH.

Biogas is a renewable energy comprising mixture of gases produced from organic matter, mostly waste, by bacteria anaerobically using digester as bioreactor. It can be burnt to generate heat, electricity or used vehicle fuel. The residual (digestate) fertilizer. This study was carried out optimize the temperature reactor and biogas yield three independent variables (K=3) namely waste biomass (yam peel, potato unripe plantain watermelon cabbage bread fruit husk, melon husk cow dung) feed stock, pH retention time designed according Box-Wilson (1951) experimental design matrix. were varied, each into five equal spaced levels; feedstock volume (6, 8, 10, 12 14) litres; (2, 4, 6, 10) (7, 14, 21, 28, 35) days. fermented inside locally fabricated biodigester for maximum 35 A total 21 runs generated subjected response surface data analysis MINITAB (version 11.21). Central Composite Rotatable Response Surface Design (CCRRSD) model employed linear, quadratic, cross product effects on reactor. Six-dimensional contour figures plotted visualize process responses with MATLAB R2007b). Results revealed that at variable combinations 6 respectively volume, time, there (4. 42 litres) (33oC i.e mesophilic temperature). Minimum values (0.95 (28oC) equally obtained 7 feedstock, time. Regression coefficient ANOVA also significant (P < 0.05) negative linear correlation positive quadratically. have interactive effect interaction pH. Coefficient determination given 62.03% 64.93% R 0.79 0.81 hence gave good fit such optimization.