Bio-Detoxification of Arsenic Laden Ground Water Through a Packed Bed Column of a Continuous Flow Reactor Using Immobilized Cells

Under the present study arsenic resistant bacterial strain, Rhodococcus equi (JUBTAs02), has been used to remove trivalent arsenic from a simulated aqueous solution of arsenic oxide (As2O3). Batch studies have been conducted to determine the arsenic-intoxicated growth kinetics of the bacteria. The Monod type kinetic parameters like saturation constant KS and maximum specific growth rate max have been determined by studying batch mode of growth of microorganisms varying the initial concentration of limiting substrate, i.e. citrate (carbon source), in absence of arsenic ions. The kinetic parameter for intoxicated growth, namely the inhibition constant, Ki, has been determined by varying As3+ concentration for each batch conducted at different initial concentrations of citrate. For ground water a first order kinetics with respect to arsenic concentration has been determined for arsenic uptake rate. The same microorganism has been used in immobilized form to treat simulated water as well as naturally occurring arsenic laden ground water in a continuous packed bed reactor using initial arsenite concentration and inlet flow rate as parameters. A maximum value of arsenite removal efficiency of 95% has been achieved in this process. Deterministic mathematical models capable of explaining the trend of removal of arsenic from simulated and ground water have been developed using the kinetic parameters of intrinsic growth of the microorganism. The simulated results have been compared with the experimental ones satisfactorily.