keywords: Bio-digester, biogas, biomass, cow dung, cassava peels, volatile solid
This research work was undertaken to design and construct a workable bio-digester and assess its yield under several conditions. The constructed digester was composed of bio-digester vessel of 20 litres capacity, the pvc pipes which serves as inlet for the substrate and the bucket which serves as the gas collector. The funnel serves as guide for loading substrate, while the PVC valve made of (2 – 5 cm) in diameter was attached horizontally to the digester vessel which serves as collection point for slurry and the metal functions as a flame regulator. The digester was used in the production of biogas by co-digestion of cow dung and cassava peels as substrate (biomass). The yield between 3-30 days ranged from 200 – 11800 cm3, respectively. The optimum yield was obtained on the 13th day with 11800 cm3 of biogas yield. Further increase in the number of days, led to decrease in the quantity of biogas produced. Variation in the pH led to variation in biogas yield. The optimum gas yield was obtained at pH of 7.45. pH (2.0-6.4) affected the yield of biogas for the constructed digester due to the increase in the growth of acidic-phobic bacteria . Temperature also influenced the biogas yield. The optimum temperature for the operation of the digester was 34oC with 11800 cm3 of gas produced. The bio-digester is workable and adaptable to our environmental conditions.