N. SinbuathongP. SiriroteB. SillapacharoenkulJ. Munakata-MarrS. ChulalaksananukulKasetsart UniversityKing Mongkut's University of Technology North BangkokColorado School of MinesMahidol University2018-06-112018-06-112012-11-01Energy Sources, Part A: Recovery, Utilization and Environmental Effects. Vol.34, No.22 (2012), 2048-205615567230155670362-s2.0-84867065271https://repository.li.mahidol.ac.th/handle/20.500.14594/14105Digestion of Jatropha curcas seed cake was investigated in two-stage (acidogenic and methanogenic) anaerobic bioreactors without pH adjustment. Acidogenic reactors were fed once daily with a slurry of 1:10 Jatropha curcas seed cake:water containing approximately 100 g of chemical oxygen demand/l. Organic loading rates were 2.5, 3.3, 5, 10, and 20 kg chemical oxygen demand/m 3 .day, which corresponded to hydraulic retention times of 40, 30, 20, 10, and 5 days, respectively, for each reactor stage. The maximum methane yield (340 l at STP/kg of chemical oxygen demand degraded) was observed at an organic loading rate of 3.3 kg chemical oxygen demand/m 3 .day (hydraulic retention times = 30 days for each stage). At this organic loading rate and hydraulic retention time, the chemical oxygen demand degradation efficiency was 65%. The average pH in the acidogenic and methanogenic reactors was 4.9 and 7.4, respectively. This study demonstrates high methane yield and degradation extent of Jatropha curcas seed cake in a two-stage anaerobic process without chemical addition for pH adjustment. © 2012 Copyright Taylor and Francis Group, LLC.Mahidol UniversityEnergyArticleSCOPUS10.1080/15567036.2012.664947