Modelling and Optimization of Biogas Production from Anaerobic Digestion of Agricultural Wastes: A Factorial Design Analysis

Abstract

The aim of this study was to investigate he thermal optimal condition of biogas production from anaerobic digestion of agricultural waste (namely cow dung, chicken waste and saw dust) using full factorial design of experiment to study the effect of four factors: concentration (A), feed type (B), seeding (C), and time (D) on biogas produced after 28days of anaerobic digestion. Main effects and interaction effects of these factors were analyzed using statistical technique. The experimental results showed that the linear model term of concentration , feed type, seeding and time had significant effect on yield with (p<0.05). However, there was interaction effect between these variables (p<0.0.5), though, concentration and time show no interaction (p<0.05). The full model equation developed for bogas production is: Y= K - 11.5842A + 19.9868D constant K for biogas production with seeding = 930.877 for cow dung, 1483.28 for chicken waste and 555.692 for saw dust respectively. While K for biogas production without seeding = 351.309 for cow dung, 903.717 for chicken waste and -23.8759 for saw dust respectively. The highest amount of biogas produced was 1973.33mL at optimum condition of 20% concentration, chicken waste, seeding and retention time of 28days.