Basnayake, Basnayake Mudiyanselage Nishantha creator Annachhatre, Ajit P. Chairperson Lens, Piet N. L. Examination Committee Thammarat Koottatep Examination Committee Shipin, Oleg V. Examination Committee Rene, Eldon Raj Examination Committee Joint Japan/World Bank Graduate Scholarship Program (JJ/WBGSP) Scholarship donor UNESCO-IHE-Asian Institute of Technology Scholarship donor text series technical report Pathum Thani, Thailand Asian Institute of Technology 2015 2014 continuing eng 126 p. : ill. + 1 online resource Cassava pulp (CP) is a major solid waste produced from the starch industries. CP can be converted to the form of methane or other biofuels with the help of a suitable co-substrate in anaerobic digesters. An optimal carbon to nitrogen (C/N) ratio is important for the success of anaerobic digestion. In this research, C/N ratio of CP was adjusted by the addition of pig manure (PM) as the co-substrate in order to enhance methane production. Two experimental reactors (semi continuously operated stirred tank reactors) of capacities 10 and 20 L were evaluated at C/N ratio's of 35 and 25, at various organic loading rates (OLRs <4.0 kgVS/m3·d) for their potential to produce biogas. The reactors were operated at ambient temperatures for 180 days. The results from this study showed that biogas production increased with an increase in the OLR from 1 to 4 kg VS/m3·d, while the methane content varied between 53 and 65% in both the reactors. Maximum methane production was achieved at an OLR of 4.0 kg VS/m3·d. The maximum biogas production rate was ~1.71 and 1.94 L/L.d at an OLR of 4.0 kgVS/m3.day in the 10 L and 20 L reactors, respectively. The highest percentage of VSremoval were 82.11 and 75.79% at an OLR of 2.0 kg VS/m3·d in both the reactors. When the OLR was increased from low to high values, the reactor operation was stable and it showed no inhibition effect from ammonia-nitrogen and VFA, as their concentrations were below the inhibitory concentration levels. Concerning cyanide concentrations in the reactors at different OLRs, their levels did not pose any inhibitory effect on the methanogenic activity nor the biogas production rate. The best C/N ratio for anaerobic co-digestion of CP and PM was found to be 25 (CP:PM=66:34). A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in Environmental Engineering and Management with specialization in Environmental Technology for Sustainable Development jointly offered by the Asian Institute of Technology, Thailand and UNESCO-IHE, The Netherlands Thesis (M.Sc.) - Asian Institute of Technology, 2014 Cassava industry Waste disposal Thailand Cassava Thailand Asian Institute of Technology. http://203.159.5.9/ait-thesis/detail.php?q=B02383 http://203.159.5.9/ait-thesis/detail.php?q=B02383 170531 20260817162225.0