Continuous removal of malathion by immobilised biomass of Bacillus species S14 using a packed bed column reactor

Abstract

Biosorption of malathion from aqueous solution was studied using Bacillus sp. S14 immobilised on calcium alginate (3%) using a packed bed column reactor at a temperature of 25 oC and a pH of 7.0. The experiments were conducted to study the effect of important design parameters such as bed height, flow rate and influent malathion concentration. Maximum removal capacity (57%) was found at 4mL min-1 flow rate, 6.0cm bed height and 25mg L-1 influent malathion concentration. The Adam-Bohart model, Wolborska model, Thomas model, Yoon-Nelson model were employed to determine characteristic parameters such as saturation concentration, external mass transfer coefficient, Thomas rate constant, the maximum solid phase concentration of the solute, rate constant, and the time required for 50% adsorbate breakthrough time, which are all useful for process design. Experimental data were well fitted with Adam-Bohart model at the lower region of effluent/influent malathion concentration values but at higher region values data fitted well with the Thomas and Yoon-Nelson models.