Faculty Publications
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Item Experimental investigation and artificial neural network-based modeling of batch reduction of hexavalent chromium by immobilized cells of newly isolated strain of chromium-resistant bacteria(2012) Shetty K, K.V.; Namitha, L.; Rao, S.N.; Narayani, M.The batch bioreduction of Cr(VI) by the cells of newly isolated chromium-resistant Acinetobacter sp. bacteria, immobilized on glass beads and Ca-alginate beads, was investigated. The rate of reduction and percentage reduction of Cr(VI) decrease with the increase in initial Cr(VI) concentration, indicating the inhibitory effect of Cr(VI). Efficiency of bioreduction can be improved by increasing the bioparticle loading or the initial biomass loading. Glass bioparticles have shown better performance as compared to Ca-alginate bioparticles in terms of batch Cr(VI) reduction achieved and the rate of reduction. Glass beads may be considered as better cell carrier particles for immobilization as compared to Ca-alginate beads. Around 90% reduction of 80 ppm Cr(VI) could be achieved after 24 h with initial biomass loading of 14.6 mg on glass beads. Artificial neural networkbased models are developed for prediction of batch Cr(VI) bioreduction using the cells immobilized on glass and Ca-alginate beads. © Springer Science+Business Media B.V. 2011.Item Bioleaching of copper from electronic waste using Acinetobacter sp. Cr B2 in a pulsed plate column operated in batch and sequential batch mode(Elsevier Ltd, 2017) Jagannath, A.; Shetty K, V.K.; Saidutta, M.B.The amount of metal content present in electronic waste (e-waste) such as printed circuit boards (PCBs) exceeds that present in rich minerals thus allowing the use of PCBs as artificial ores. The copper content in PCBs is 10-30 mass %, which is the highest among all the metallic elements. The recovery of copper from e-waste serves dual fold benefit of conservation of metal resources and overcoming environmental hazard due to e-waste accumulation. In the currently reported study, a pulsed plate bioreactor in which the inter-plate spaces were packed with e-waste material was effectively employed for bioleaching of copper from e-waste using Acinetobacter sp. Cr B2. Various factors such as inoculum size, e-waste loading, frequency and amplitude of pulsation that significantly affected the bioleaching efficiency were studied. Inoculum size of 9% (v/v), frequency of 0.2 s-1, amplitude of 6.5 cm and total e-waste loading of 40 g with 10 g/stage were found to provide maximum bioleaching of Cu. Around 23% of Cu bioleaching was achieved under these conditions by batch mode of operation. Increasing the number of sequential cycles of operation in sequential batch mode further improved the bioleaching efficiency, by overcoming the maximum copper solubility and growth limitations of the single batch operation. With five cycles of sequential batch operation around 63% leaching of Cu could be achieved. The bioleaching was found to be mediated both by the action of extracellular enzymes and metabolites. The study demonstrated the potential application of pulsed plate bioreactor for larger scale application of copper bioleaching from PCBs. © 2017 Elsevier Ltd. All rights reserved.