STUDIES ON THE COMPOSTING OF GARDEN AND KITCHEN WASTES

AUTHOR: EZUE CHINYELU PATRICIA

DEPARTMENT: APPLIED MICROBIOLOGY AND BREWING

AFFILIATION: NNAMDI AZIKIWE UNIVERSITY, AWKA

Investigations were conducted into the physico-chemical conditions and microbial community (mesophilic bacteria and fungi) present in garden and kitchen wastes. Two trenches, ‘Run A’ (containing garden and kitchen wastes which is the control) and ‘Run B’ (the test, containing garden and kitchen wastes in addition to grape fruit peels) were constructed. The indoor method of composting was employed, for an experiment that lasted for a period of 11 weeks. The bacterial species isolated were Staphylococcus, Bacillus, Acetobacter, Alcaligenes, Micrococcus and Beijerinckia spp., while Aspergillus, Rhizomucor, Cunninghamella, Scopulariopsis, Trichoderma, Gliocladium and Exophiala were the species of fungi isolated during the composting. Staphylococcus, Beijerinckia and Aspergillus disappeared at the 11th week of the composting, implying that the compost had become sanitized. The bacterial isolates were prevalent over fungal isolates (peak values obtained for bacteria were 3.0 x 109 cfu/g in ‘Run A’ and 1.21 x 109 for ‘Run B’, for fungi 3.0 x 105 cfu/g in both runs), with Bacillus being the predominant organism. Runs ‘A’ and ‘B’ attained stability at the 11th week with the C: N ratio of 6.88 and 6.78 for Runs ‘A’ and ‘B’ respectively. The organic matter decreased for both runs from week 0 to the week 4 and assumed constant weights of 20 and 10 for Runs A and B respectively by the 11th week. The ash content, in contrast to organic matter content increased in both runs and assumed a constant value after the 4th week, implying the maturity of the compost. The ash content for ‘Run A’ increased from 10 to 49 and 6.5 to 49.5 for ‘Run B’. The pH and temperature had effects on the organic matter degradation of ‘Run A’ and ‘Run B’, since a drop in pH and a temperature of 450C aid in the degradation, ‘Run B’ had a faster rate of degradation of organic matter, due to the addition of grape fruit peels. The nitrogen content increased for both runs from 0.63% in ‘Run A’ and 0.6% in ‘Run B’ to final values of 1.96% and 1.4% respectively. Analysis for (NH4 +/NO3 -)-N showed that the values of NH4 +-N decreased, while the NO3 _-N increased, though at the initial stage of composting, the low NH4 +-N did not coincide with NO3 –N, due to loss of NO3 –N as a result of denitrification. Nitrogen retention was higher in Run A with a value of 0.634, while ‘Run B’ had a value of 0.304. The addition of grape fruit peels did not significantly increase retained nitrogen in the experiment though it was able to put a check on the pH of ‘Run B’ by stabilizing it to the pH value of 7.

TO VIEW THE FULL CONTENT OF THIS DOCUMENT, PLEASE VISIT THE UNIZIK LIBRARY WEBSITE USING THIS LINK, http://www.naulibrary.org/dglibrary/admin/book_directory/Thesis/10312.pdf

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