The utilisation of cellulosic biomass in the treatment of acid mine drainage and the subsequent production of fermentable sugars for bioprocessing
Date
2015-02-16
Authors
Magowo, Webster
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Abstract
Sugar cane bagasse and switch grass were used to investigate their potential in the remediation
(decreasing metal ion concentration and increasing pH) of Acid Mine Drainage (AMD) and the possibility
that the AMD residue sludge containing cellulose could be further hydrolysed using a commercial
cellulase enzyme system to produce glucose for bioprocesses. In general both the feedstocks series
appeared to increase pH and reduce dissolved iron concentration after being incubated with AMD for a
period of 14 weeks at room temperature. The milled switch grass was shown to have a greater
remediating effect on AMD, raising the pH from 2.11 to 5.46, and decreasing iron concentration from
500mg/l to 174mg/l, a decrease of 62%. The sugar cane bagasse was shown to have the least remedial
effect, increasing pH from 2.11 to 2.38, and only reducing iron concentration by 30%. The 2‐5cm switch
grass raised the pH from 2.11 to 3.86, and the iron concentration was reduced from 500mg/l to
283mg/l, a 42% reduction. The milled grass series was chosen for further enzymatic hydrolysis. The
milling reduced the size of the switch grass and destroyed the cell structure making it more accessible to
AMD treatment. This also allowed the enzyme in the hydrolysis to penetrate to the fibres and reach the
sugar oligomers. The sludge of the AMD treated switch grass was incubated with cellulases enzymes for
24 hours at 50oC, producing glucose concentration of up to 4,86mg/ml.
Description
A dissertation submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfilment of requirements for the degree of Master of Science. 2014.