REMOVAL OF HEAVY METALS FROM REFINERY EFFLUENT USING SUGARCANE BAGASSE INOCULATED WITH ASPERGILLUS FLAVUS AND TRICHOPHYTON SPECIES

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Date
2017-08
Authors
MUHAMMAD, MURJANATU ABDULLAHI
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Abstract
Physicochemical properties of most refinery effluents have been reported to consist of a variety of hazardous substances including heavy metals, which pose a threat to the ecosystem. Studies were carried out with the aim of testing the ability of two fungal isolates, namely Trichophyton species and Aspergillus flavus in removal of Nickel (Ni), Mercury (Hg) and Arsenic (As) from refinery effluent, with sugarcane bagasse serving both as growth medium and as a component of the experimental biosorbents. The physicochemical properties of the effluents were determined following standard procedures. The Proximate composition of the sugarcane bagasse as well as its ability to support growth of the Aspergillus flavus and Trichophyton species were determined. The performances of the experimental sorbents in the removal of Ni, Hg and As were also determined using fixed bed sorption columns. It was observed that the raw refinery effluent was highly turbid (111NTU) with high electrical conductivity (717μS/cm) and chemical oxygen demand (874.10mg/l). The levels of Nickel (1.149mg/l) and Mercury (484.780mg/l) were also found to be higher than permissible limits, while Arsenic was not detected. It was also noted that the sugarcane bagasse consists chiefly of cellulose (46.5%), hemicellulose (23.61%) and lignin (21.4%) with capacity to support luxuriant growth of Trichophyton sp. and Aspergillus flavus. The optimum time of Nickel and Mercury uptake by all the treatments was observed to be 1hr after the start of the experiment, and equilibrium was reached between 5-6hrs and at 4hrs for Nickel and Mercury adsorption respectively. The study also showed that both fungal isolates as well as the sugarcane bagasse had the ability to remove Nickel and Mercury ions from refinery effluent with more than 90% efficiency. The unsterilised and un-inoculated sugarcane bagasse removed more Mercury ions (97.6%) than the fungal cultures, while in Nickel removal; the sterilised sugarcane bagasse inoculated with Aspergillus flavus had the highest performance (97.1%). It was therefore concluded that the refinery effluent was highly polluted and hazardous to the environment and aquatic organisms, thus, improved treatment is required before releasing into receiving water. Also, sugarcane bagasse is a suitable medium for growth of fungi as well as removing heavy metal ions from refinery effluent. Data analysis carried out using one-way Analysis of Variance showed that there was a significant difference between the performance of the sorbents in the removal of Ni ions only (p=0.00); while no marked difference was observed statistically (p>0.05) between the performance of un-inoculated sugarcane bagasse in removing and adsorbing the heavy metal ions from solution with that of the sugarcane bagasse inoculated with the test fungal isolates used in this study both separately and as co-culture, as each of the sorbents proved to be very efficient.
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A DISSERTATION SUBMITTED TO THE SCHOOL OF POSTGRADUATE STUDIES, AHMADU BELLO UNIVERSITY, ZARIA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE AWARD OF MASTER OF SCIENCE IN MICROBIOLOGY DEPARTMENT OF MICROBIOLOGY, FACULTY OF LIFE SCIENCES, AHMADU BELLO UNIVERSITY, ZARIA, NIGERIA
Keywords
REMOVAL OF HEAVY METALS,, REFINERY,, SUGARCANE,, BAGASSE INOCULATED,, ASPERGILLUS FLAVUS,, FLAVUS,, TRICHOPHYTON SPECIES,
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