Performance evaluation of three different-shaped bio-digesters for biogas production and optimization by artificial neural network integrated with genetic algorithm

Abstract

This study focused on the effect of bio-digester shape on biogas production. Bio-digesters of 15-dm3 each with different shapes (cylindrical, cubical and conical) were constructed and their performances for biogas production were investigated using poultry droppings. Also, the performance of the best bio-digester was further assessed using poultry droppings, cow dung and piggery waste. Additionally, the biogas production process was modeled and optimized by co-digesting plantain peels with the animal wastes using the best bio-digester. The average daily biogas productions for cylindrical, cubical and conical-shaped bio-digesters were 0.58, 0.46 and 0.36 dm3/day, respectively. Using 2.5-dm3 cylindrical-shaped bio-digesters, daily average biogas productions for cow dung, poultry droppings and piggery waste were 0.40, 0.23 and 0.01 dm3/day, respectively. Using the developed model coupled with genetic algorithm, the optimum biogas production was 13.65 dm3 with substrate combination of 0.7 kg of poultry droppings, 0.0004 kg of cow dung, 0.6 kg of piggery waste and 0.2 kg of plantain peels. The results showed cylindrical-shaped bio-digester was the best for biogas production, while cow dung gave the highest biogas production. The study demonstrated that maximum biogas production could be obtained using combination of animal wastes supplemented with plantain peels.