Biodesulfurization of hydrodesulfurized diesel in a trickle bed reactor—Experiments and modeling

Abstract

Hydrodesulfurized diesel [sulfur content, 200-540 ppm (mg/dm³)] has been used for bio-desulfurization using <i style="">Rhodococcus sp.</i> Biomass concentration with the progress of time has been determined using dry cell weight method. Batch studies have been conducted with a two phase medium [non-aqueous to aqueous phase ratio, 10:90 to 100:0 (<i>i.e.</i> 0-100% diesel)]. Sulfur concentration has been determined using a Universal Oil Products (UOP) standard method (UOP 357-80). Microbial strains have been observed to follow classical Monod type growth kinetics under the present range of substrate concentration. A systematic and programmed analysis was made to determine following intrinsic kinetic parameters: maximum growth rate (µ_max), 0.096 h^-1; and half saturation constant (Ks), 71 mg/dm³. Biodesulfurization of hydrodesulfurized diesel has been conducted in a trickle bed reactor (diam, 0.066 m; height, 0.6 m) under continuous mode. Pith balls have been used as the immobilization matrix for the microorganisms with a constant bed porosity of 0.6. Flow rate of inlet diesel has been varied (0.25-0.5 dm³/h). Sulfur conversion up to 99% has been achieved. A mechanistic mathematical model, developed for the trickle bed bioreactor, can explain the reality satisfactorily.