COMPARATTIVE STUDY OF BIOGAS YIELD FROM DIFFERENT ANIMAL WASTE MIXTURES

AUTHOR: CHUKWUMA EMMANUEL CHIBUNDO

DEPARTMENT: AGRICULTURAL AND BIORESOURCES ENGINEERING

AFFILIATION: NNAMDI AZIKIWE UNIVERSITY, AWKA

The study of biogas production was conducted for selected animal wastes (cow dung, poultry and pig droppings) in different mixing ratios. The mixing ratio of 100: 0, 75: 25, 50: 50, 25:75 and 0:100 were used to determine the optimum mixing ratio for poultry droppings (PYD) and cow dung (CD); pig droppings (PGD) and cow dung; poultry and pig droppings in five 30 litres digesters, designed and constructed for the purpose of the experiment. The maximum biogas production potential for the cow dung and poultry dropping mixture is in the order of 25%CD + 75%PYD > 100%CD + 0%PYD > 50%CD + 50%PYD > 0%CD + 100%PYD > 75%CD + 25%PYD. The optimum mixing ratio for cow dung and poultry dropping is the 25%CD + 75%PYD mixing ratio with 16.35L/TMS within the period under study. The mixture effect of Pig droppings with cow dung investigated in this research work shows that the maximum biogas production potential for the pig dropping and cow dung mixture is in the order 50%PGD + 50%CD > 0%PGD + 100%CD > 25%PGD + 75%CD > 75%PGD + 25%CD > 100%PGD + 0%CD. Thus the 1:1 mixture ratio of pig droppings to cow dung is the optimum mixing ratio, obtained from 50%PGD + 50%CD digester. Also the maximum biogas production potential for poultry and pig dropping mixture ratios is in the order 100%PYD + 0%PGD > 50%PYD + 50%PGD > 75%PYD + 25%PGD > 25%PYD + 75%PGD > 0%PYD + 100%PGD. The kinetics of anaerobic digestion process of the various digestion mixtures were also evaluated. The result shows that poultry dropping alone has the highest short term biodegradability index of -2.4 while the 50%CD+50%PYD digester has the highest removal rate of the biodegradable fractions (k) of -0.199 among cow dung and poultry droppings mixtures. The 50%PGD + 50%CD digester could not fit the linear polynomial model. The model was able to fit the data set with a goodness of fit (R2) of 0.9768 using cubic polynomial. The room temperature short term biodegradability index was 3.1 while the removal rate of the biodegradable fractions (k) was -0.061. These kinetic parameters used in assessing the substrates performance agrees with the experimental results and shows that the 50%CD+50%PYD digester has the overall best performance. 

TO VIEW THE FULL CONTENT OF THIS DOCUMENT, PLEASE VISIT THE UNIZIK LIBRARY WEBSITE USING THIS LINK, http://naulibrary.org/dglibrary/admin/book_directory/Thesis/11050.pdf

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