A bioleaching process to extract rare earth elements (REE) from fluidized catalytic cracking (FCC) catalysts was optimized using a heterotrophic bacterium Gluconobacter oxydans to produce organic acids from glucose. Parameters optimized included agitation intensity, oxygen levels, glucose concentrations and nutrient additions. Biolixiviants from the optimized batch process demonstrated REE leaching efficiencies up to 56%. A continuous bioreactor system was subsequently developed to feed a continuous leach process and demonstrated leaching efficiencies of 50%. A techno-economic analysis showed glucose to be the single largest expense for the bioleach process constituting 37.8% of the total cost. The bioleaching plant described here wasmore »
Impact of mineral precipitation on flow and mixing in porous media determined by microcomputed tomography and MRIHere, precipitation reactions in porous media influence transport properties of the environment and can control advective and dispersive transport. In subsurface environments, mixing of saline groundwater or injected solutions for remediation with fresh groundwater can induce supersaturation of constituents and drive precipitation reactions. Magnetic resonance imaging (MRI) and micro-computed tomography (µ-CT) were employed as complimentary techniques to evaluate advection, dispersion and formation of precipitate in a 3D porous media flow cell. Two parallel fluids were flowed concentrically through the porous media under two flow rate conditions with Na 2CO 3 and CaCl 2 in the inner and outer fluids, respectively.more »
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