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UPSI Digital Repository (UDRep)
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| Abstract : Universiti Pendidikan Sultan Idris |
| The high cost of culture growth medium is one of the problems faced in the scaling-up of biological processes involved in wastewater treatment. This makes it imperative to find a useful, cheap and easily available alternative source for culture growth medium. The possibility of using sugarcane bagasse (SCB), solid pineapple waste (SPW) and soybean meal (SBM) as alternative sources for culture medium is preferable as these agricultural wastes are easily available, cheap and abundantly grown. The present work highlights the use of SCB, SPW and SBM to sustain the bacterial population for the Cr(VI) reduction process. Growth of A. haemolyticus in agricultural wastes was measured by optical density (00600) followed by viable cell counts. Reduction of Cr(VI) was determined using diphenylcarbazide method. For all Cr(VI) concentrations tested (10-100 mg/L), SCB-adapted A. haemolyticus showed the highest reduction ranging from 92-99% followed by SPW and SBM with 40-94% and 21-85% reduction respectively. From the FESEM-EOX analysis, toxicity effect can be seen clearly from the shape of bacteria in the presence of 100 mg/L Cr(VI). The FT-IR analysis showed shifting of the C-O band absorption peak from 1252-1261 ern" and 1048-1037 cm-I after Cr-Ioaded which was due to the binding of Cr(VI) to this functional group. In this study, down-ward biofilm packed-bed reactor was used. A minimum of 4 h was required for complete reduction of Cr(VI) to Cr(III) at the flow rate of 3.0 mUmin using 25 mg/L initial Cr(VI) concentration. Cr(Vl) reduction mechanism study using XPS and ESR implies that the Cr bound to the SCB and SCB-adapted A. haemolyticus were mostly in trivalent form. SCB can serve as an alternative and cost-effective growth medium for cultivation of A. haemolyticus with high percent reduction of Cr(VI). Phylogenetic analysis revealed that the microbial community was dominated by Chitinophaga terrae, Laribacter ho ngkongensis, Ottowia thiooxydans, Rhizobium cellulosilyticum, Candidate division OPIO, Pedobacter sp. and uncultured bacterium. |
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