Browsing by Author "Tesfamichael Awoke"

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    Experimental Investigation of Solid-Liquid Separator and Solar Tunnel Dryer for a Biogas Digestate
    (Addis Ababa University, 2023-06) Tesfamichael Awoke; Wondwossen Bogale (PhD)
    Through the 20th century, higher energy demand, fossil fuel depletion, environmental pollution problems and waste management requirements led the development of biogas production technology. However, the biogas plant's slurry/digestate, causes significant environmental issues since it pollutes the soil, water, and air through the release of phosphate and nitrate gases. With the use of mechanical and thermal treatments, digested biogas waste is suitable for use as fertilizer or a soil amendment. In order to use biogas digestate as fertilizer, to minimize environmental pollution and to store and transport it securely and conveniently; liquid components must first be separated mechanically by presses (solid-liquid separator) and then thermally by vaporization (dryer). This study examines the fundamental design of the screw type solid-liquid separator and solar tunnel dryer, manufacturing and laboratory investigations, as well as characterize both the solid and the liquid portions’ suitability from the mechanical and thermal parameters such as the portions’ final moisture content. By using both the separator and dryer, the moisture content (the liquid fraction) of the fresh biogas digestate is able to reduce from 75% to 5% ( from 75% to 40% using the separator and from 40% to 5% using the solar dryer). The separator has a capacity of separating 7.5m3 of digestate at 8 hours and the dryer has the capacity to dry 2m3 of digestate at a drying time of 3 days, 7-8 hr. per day at the experimentation site Addis Ababa, 8.9806° N, 38.7578° E. Both the separator and dryer has a cost of approximately 35,000 ETB.