Enhancement of Biogas Production from Sawdust through Sustainable Alkaline and Biological Pretreatment Methods

Abstract

This study aims to enhance biogas production from sawdust fibers Quercus genus (oak) using sustainable pretreatment methods. Sawdust and poultry dung (substrates) were obtained in Ogbomoso and delignification of oak samples was carried out through gravimetric method on 5, 10, and 15 days before and after digestion. Physico-chemical parameters were analyzed according to American Public Health Association (APHA) (2018) standard. Anaerobic digestion on substrates was performed through alkaline and biological pretreatment processes, biogas samples were collected and analyzed using gas chromatograph mass spectrometer. Pretreatment results for delignification of raw sawdust, alkaline and biological pretreated at 5, 10 and 15 days were; 13.5, 2.0, 1.5, 1.0 and 1.0 in mg/l. Physico-chemical results of substrates before and after digestion respectively were; pH (7.38, 8.12); alkalinity (350, 475); Nitrogen (25.5, 38.2); Phosphorus (2.67, 2.43); Carbon (192.8, 342.1); Potassium (4.1, 3.5); Phosphate (56.0, 128); Sulphate (74.0; 69.0), Calcium (12, 44); Magnesium (65, 36); Manganese (0.010, 0.031), Iron (5.2, 6.1); Zinc (25.0, 17.4); Aluminium (0.35, 0.34); Copper (2.5, 2.5); Biochemical Oxygen Demand (110, 175); Chemical Oxygen Demand (964, 1440); Carbon/Nitrogen ratio (8:1, 9:1); Volatile Solids (1216, 4560); Moisture Content (25.8%, 63.1); Total Solids (66.2%, 17.8%) and Volume of Solids (58.2%, 77.7%) in mg/l. Biogas samples composition from biological and alkaline pretreatments were: Methane (65.05%, 62.27%); and Carbon Dioxide (17.51%, 13.28%). Both pretreatment methods produced enough methane percentages, but biological pretreatment performed better. This work is applicable in sustainable biogas production for environmental protection.