BIOGAS PRODUCTION FROM CO-DIGESTION OF RICE HUSK, CASSAVA PEEL, ANDPOTATO PEEL IN LAFIA, NASARAWA STATE, NIGERIA

Abstract

0.5 kg of agricultural waste samples (cassava peel and rice husk, CP/RH; rice husk and potatoes peel, RH/PP; and potatoes peel and cassava peel, PP/CP) were mixed in a ratio of 1:1 and co-digested in 5 L capacity of fabricated digester. Experiment was carried out for a period of 7 weeks at room temperature and evaluated for mineral content in the undigested and digested waste materials, biogas generation, and proximate compositions. The mineral compositions of the undigested and digested waste samples after Flame Photometry and Atomic Absorption Spectrophotometer (AAS) show that the digested samples contain a higher concentration. The elemental concentrations of the waste samples ranged from 0.5532 mg/g of Sodium in undigested RH to 18.2412 mg/g in the digested sample of CP. The weekly cumulative generation of biogas after 7 weeks at a room temperature range of 29 – 34 °C shows that the PP/CP has the highest yield of 18.81 mL/g VS, followed by the RH/PP 16.79 mL/g VS, and the CP/RH sample 15.40 mL/g VS, respectively. The volume of the biogas generated for CP/RH, RH/PP, and PP/CP samples decreases at week 7 from 2.76 mL/g VS to 2.49 mL/g VS, 2.92 mL/g VS to 2.76 mL/g VS, and 3.44 mL/g VS to 3.23 mL/g VS. The proximate composition of the waste shows that rice husk had the highest percentage of volatile solids (19 %), ash, and crude protein (6.91 %), potatoes peel had highest moisture content (54 %), while RH had the highest C/N ratio of 82:1