Bioleaching kinetics of trace metals from coal ash using Pseudomonas spp.

The kinetics of bioleaching of chromium, copper, manganese and zinc from coal ash using Pseudomonas spp. isolated from coal ash pond was investigated. From the previous study, parameters used for bioleaching were 1% pulp density, 90 rpm, 37°C and 5 ml inoculum was placed in a 100 ml fresh medium with the ash. These conditions were used for bioleaching of coal ash for 30 days. Moreover, the initial pH of the solution is 8.20 and decreases to 8.61. After 30 days of bioleaching, the maximum metal leached were 13.77% Cr, 14.61% Cu, 6.33% Mn and 12.18% Zn. Assuming that the coal ash will shrink uniformly with respect to time using Shrinking Core Model, the kinetic data showed linear plot for percent metal leached versus time, suggested that diffusion through ash layer control was the rate controlling mechanism.