Biodigestion Effects of Cow Dung, Poultry Droppings and Maize Cobs on Microbiological and Physico-Chemical Properties of the Effluents

Abstract

Purpose: To assess its effects on microbial community, biogas yield and some physico-chemical properties of the effluents. Methodology: Triplicate slurries of each of the biomass were separately loaded into locally constructed batch-reactor systems, under strict anaerobic condition and kept for eight(8) week retention period. Separate treatment fractions were subjected to standard methods to determine their microbial contents before and during anaerobic digestion (AD). Weekly variations in temperature and weight were followed during the retention period. Findings: The microbial isolates included 7fungal species, Six (6) non-methanogens, four (4) methanogens and two (2) yeasts. Only Chaetomium thermophile, Aspergillus fumigates and Aspergillus nidulans were isolated at the 5th WOD. The methanogens were predominantly present throughout the digestion period, with increased frequency of occurrence ranging from 50-100%. There was a general % reduction in total viable counts for all microbial isolates, except for the methanogens, with %increase ranging from 83.48% -205.42%. Treatments E(2961.0ml) and B(1713.2ml) had the highest and lowest significant(p < 0.05) cumulative biogas production, with the co-substrates yielding more than the mono-substrates. All treatments showed progressive temperature rise and average weight loss, which suddenly dropped after the 6th and 4th WOD respectively, with the average weight loss ranging from 23.7±1.9 to 34.3±4.6. Contribution to theory, practice and policy: There was a strong positive correlation between gas production and weight loss as well as with temperature variation. This initiative engendered alternative energy source, agro-wastes management, while ensuring sustainable environmental rejuvenation.