Two-Stage Anaerobic Digestion of Aerobic Pre-Treated Sisal Leaf Decortications Residues: Hydrolases Activities and Biogas Production Profile
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Date
2008
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Abstract
A two-stage system was investigated for anaerobic digestion (AD) of aerobically pre-treated sisal leaf
decortication residue (SLDR) with regard to hydrolytic enzymes and biogas production. The system
consisted of a solid-bed bioreactor for hydrolysis connected to methanogenic bioreactor packed with
sisal fibre decortication residues (SFDR) as biofilm carriers. Some of the enzymes produced by
microorganisms to hydrolyse SLDR were found to be pectinase, filter paper cellulase, amylase, -
glucosidase, carboxylmethyl cellulase, xylanase and protease. Enzyme activities observed in the
acidogenic bioreactor were much higher than those in the methanogenic bioreactor. The hydrolysis and
the methanogenic stages were well separated, as indicated by the high carbon dioxide production, high
volatile fatty acids (VFAs) concentration and low pH in the acidogenic bioreactor compared with high
methane production, low VFAs concentration and above neutral pH in the effluent of the methanogenic
bioreactor. Digestion of SLDR gave energy yields of 2.45 kWh/kg volatile solids added in the form of
methane. The integrity of the methane filter was maintained throughout the period of operation
producing biogas with 51 - 70% methane content. A stable effluent pH showed that the methanogenic
bioreactor had good ability to withstand the variations in load and VFAs concentrations that occurred in
the two-stage process. In conclusion, the results of this study showed that the two-stage system was
suitable for effective stabilization and biomethanation of SLDR.
Description
Keywords
Anaerobic digestion, Two-stage, Sisal decortications residues, Aerobic pre-treatment, Biogas, Hydrolases
Citation
Mshandete, A.M., Björnsson, L., Kivaisi, A.K., Rubindamayugi, M.S.T. and Mattiasson, B., 2008. Two-stage anaerobic digestion of aerobic pre-treated sisal leaf decortications residues: hydrolases activities and biogas production profile. Afr J Biochem Res, 2(11), pp.211-218.