Enhancement of kinetics of anaerobic digester for sisal leaf decortication residues by mechanical pre-treatment

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University of Dar es Salaam
The study was done to address the challenges facing Katani limited at Hale biogas plant. This plant was built as a pilot before building other biogas plants. The challenges were high retention time of substrate which was SDR, low biogas productivity, high investment costs due to large tanks sizes and low plant availability. The study was conducted at Hale biogas plant. SDR were digested and biogas yield and its composition, VFA’s and alkalinity were measured during the process while TS, VS and COD were measured before and after digestion. From the study, it was discovered that, when particles sizes were reduced below 1 mm in diameter biogas production increased and degradation of SDR also increased. Volume of biogas increased by 30% and 146% for reduced SDR compared to raw size SDR that digested at atmospheric condition and 40°C respectively with no significant change in biogas composition. SDR degradation measured in TS and VS removal efficiency, showed increase in degradation of about 5% for the reduced particles sizes compared to raw particles sizes. Biodigesters were stable in all loading condition with maximum A/TIC ratio of 0.336. The study concluded that, SDR is good raw material for biogas production when particle sizes reduced to 1 mm diameter. To maximize production, digestion must be conducted at high temperature around 40°C with constant monitoring and control of all parameters. To increase plant availability, pre-treatment of the raw SDR must be applied to remove the remaining fibres and reduce SDR size.
Available in print form, East Africana Collection, Dr. Wilbert Chagula Library, Class mark (THS EAF TD756.45.R34)
Sewage, Purification, Anaerobic treatment, Biogas, Agricultural waste as fuel
Rajabu, Y.R. (2014) Enhancement of kinetics of anaerobic digester for sisal leaf decortication residues by mechanical pre-treatment, Master dissertation, University of Dar es Salaam, Dar es Salaam