Rate Parameters for Methyl tert-Butyl Ether Biodegradation via a Radial Diffusion Model

A dimensionless radial diffusion model was employed to determine the first-order biodegradation rate of methyl tert-butyl ether (MTBE) by indigenous microorganisms at a laboratory scale in natural soils at different temperatures and oxygen concentrations. Variations in the biodegradation rate in response to different temperatures and oxygen concentrations were modeled by adjusting only the reaction-diffusion Thiele modulus to match the observed concentrations of the bulk fluid. The model can provide estimates for other unmeasured transport parameters such as intra-particle diffusion coefficient and mass-transfer coefficient at porous soil particle surfaces. Experimental data suggested that MTBE biodegradation follows first-order kinetics for different temperatures and oxygen concentrations. The biodegradation rate of MTBE by the microorganisms under different oxygen treatments (0-100%) ranged from 0.0015 to 0.0165 h^–1. Similarly, the biodegradation rate of MTBE at different temperatures (288-303 K) ranged from 0.005 to 0.03 h^–1, increasing with temperature. The rate reached its peak value at 20% oxygen concentration, and decreased substantially at higher oxygen concentrations.