Effect of Post-Treatment (Composting) Methods of Digestate from Dry Fermentation on Compost Quality
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Date
2013-12-05
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Abstract
Over the years, the volume of municipal solid waste (MSW) from various communities has been increasing day by day as a result of rapid growth in population and urbanization. This has brought about major sanitation problems in towns and cities in the country. The growing waste quantity and its detrimental effects on humans and their environment has led to the invention of various processes for treating the organic fraction of municipal solid waste stream.
Dry anaerobic digestion is currently gaining prominence because of its easy application. However, digestate, the by-product of digestion, if not utilized will add up to various waste streams. Composting, which involves the aerobic biological decomposition of organic materials, can be employed to post-treat the digestate to produce a stable humus-like product.
The objective of this study was to conduct a comparative study of untreated digestate and post-treated digestate from three different methods of post-treatments (composting). To achieve the objective, the physicochemical parameters of the digestate from a dry anaerobic digestion plant at Kwame Nkrumah University of Science and Technology (KNUST) were analyzed after which the digestate was post-treated for 58 days with three different methods of composting: vermicomposting, turned windrow composting and co-composting digestate with fresh food waste. Temperature was monitored daily and the physicochemical parameters of the composts produced were analyzed to determine the effects of each of the composting methods on the quality of composts produced.
At the end of the study, it was realized that vermicomposting yielded the best quality compost and considered the best method for composting of the digestate, since it had all its physicochemical parameters falling within the standard values required for composts. The co-compost, however, produced the lowest quality compost.
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A thesis submitted to the School of Graduate Studies, Kwame Nkrumah University of Science and Technology in partial fulfilment of the requirement for the award of Master of Science in Environmental Resources Management, October-2013