ABSTRACT Comparative phosphorus removal capability of a microbial fungus-Aspergillus terreus and a
bacterium-Bacillus subtilis from Nigeria’s Agbaja iron ore was investigated. Manual crushing
and sieving of the iron ore in Shital Test Kits produced 5 grain size distributions namely:
≥1.0mm, 1.0mm/0.50mm, 0.50mm/0.25mm, 0.25mm/0.125mm, 0.125mm/0.00mm, from which the
first and last grain sizes were excluded from the experiment on technical grounds. Then 1g of
each of the remaining 3 grain sizes was carefully weighed for each set of experiment. Culturing
and subsequent inoculation of the microbes (which are native to the iron ore) in conical flasks
containing sterilized, weighed iron ore samples in 100ml of equally sterilized malt extract and
nutrient broths were left to stand for 7 weeks in the laboratory. At weekly interval, the samples
were removed, treated through series of chemical reactions to obtain ammonium phosphomolybdate
precipitate which was back-titrated with 0.1 N-HCl to determine the amount of
phosphorus left in samples and consequently, the amount removed. The research found out
Aspergillus terreus and Bacillus subtilis have separately and successfully removed phosphorusa
deleterious non-metalic inclusion from Nigeria’s Agbaja iron ore, which previously defiled all
attempts at phosphorous removal and beneficiation techniques. However their ability at
phosphorus removal was promising and varied with the grain sizes of ore. Across all grain sizes
used, 58% and 66% phosphorus was removed in 7 weeks, respectively by the two microbes. It
was also obvious that the capacity of the microbes in removing phosphorus was seriously
hampered by a decline in activity as indicated by the reduction in microbial population in the
microcosm. For B. subtilis the density of viable cells increased from an initial load 3.4 x 105 cfu/ml, at the beginning of experiment, to 2.2 x 107 in 2 weeks but later declined to 0.9 x 106 cfu/ml at the end of 7 weeks. For A. terreus the initial biomass weight of 1g inoculated increased to 1.993 g dry weight within 3 weeks but later decreased to 0.910g dry weight in the 7th week. The reduction in microbial activity may be attributed to antimicrobial components of the ore, pyrite, and other heavy metals which may have affected the phosphorus uptake from ore. Our findings have confirmed the stronger phosphorus removal capability of B. subtilis under submerged culture technique. It is however suggestive that A. terreus may perform optimally if the submerged medium is constantly aerated.
Cite this paper
C. Anyakwo and O. Obot, "Phosphorus Removal Capability of Aspergillus Terreus and Bacillus Subtilis from Nigeria’s Agbaja Iron Ore," Journal of Minerals and Materials Characterization and Engineering, Vol. 9 No. 12, 2010, pp. 1131-1138. doi: 10.4236/jmmce.2010.912082.
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