Effect of Aerobic Pre-Treatment on Production of Hydrolases and Volatile Fatty Acids during Anaerobic Digestion of Solid Sisal Leaf Decortications Residues
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Date
2008
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Abstract
The effect of aerobic pretreatment on the production of hydrolases and volatile fatty acids during
anaerobic digestion of solid sisal decortications leaf residue (SLDR) was investigated. Batch solid
waste bioreactors with working volume of 2 litres were used in this study. Batch loads of aerobically
treated or untreated sisal leaf residue inoculated with activated sludge mixed culture were packed into
the bioreactors and operated anaerobically for 400 h. The fermentation products were mainly (mg/g
total volatile fatty acids, VFAs): acetic acid (287), n-butyric acid (201), n-valeric acid (96) and caproic
acid (62) as well as with low amounts of propionic acid and iso-butyric acid for aerobic pre-treated sisal
leaf waste solids. Contrarily, for the untreated system, the fermentation products were chiefly (mg/g
total volatile fatty acids): propionic acid (317), iso-butyric acid (276), n-butyric acid (96), acetic acid (84)
and insignificant amounts of n-valeric acid, iso-valeric acid and caproic acid. Although the activities of
hydrolytic enzymes found were similar for both treated and untreated SLDR, proportions of VFAs
obtained with the former residues appeared to be better substrates for biomethanantion than those
obtained from the latter substrates. These results indicated the potential of aerobic pre-treatment for
enhanced bioconversion of SLDR. The present study, reports for the first time the types and levels of
VFAs and hydrolases produced during anaerobic digestion of aerobic pre-treated SLDR and could be
used as a basis for designing a pilot scale process.
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Keywords
Aerobic pre-treatment, Hydrolases, Volatile fatty acids, Anaerobic digestion, Sisal leaf decortications residues
Citation
Mshandete, A.M., Björnsson, L., Kivaisi, A.K., Rubindamayugi, M.S.T. and Mattiasson, B., 2008. Effect of aerobic pre-treatment on production of hydrolases and volatile fatty acids during anaerobic digestion of solid sisal leaf decortications residues. Afr. J. Biochem. Res, 5, pp.111-119.