Hydrogen sulfide removal from biogas using a salak fruit seeds packed bed reactor with sulfur oxidizing bacteria as biofilm

Abstract

A packed bed reactor was evaluated for hydrogen sulfide (H2S) removal by sulfur-oxidizing bacteria attached as a biofilm on salak fruit seeds (SFS). The bacteria were isolated from the sludge of the wastewater of a biogas plant. The promising isolate from the previous work was used in a biofilter, and its capacity to remove H2S was evaluated at effects of time of operation, effects of biogas flow rate, effects of axial distance, and packing material. Obtained results showed that isolate attached to SFS in an 80 cm height and 8 cm inside diameter biofilter column could decrease H2S in biogas from 142.48 ppm to 4.06 ppm (97.15% removal efficiency) for a biogas flow rate of 8550 g m3 h1 corresponding to a residence time of 4 h. Simple kinetic models of sulfide removal and bacterial growth was proposed to describe the operation of the biofilter. The radial H2S concentration gradient in the flowing gas is to be neglected so is the H2S concentration in the biofilm at certain axial distance. Meanwhile, the rate of H2S degradation was approximated by Monod type equation. The obtained simultaneous ordinary differential equations solved by Runge-Kutta method. Comparing the calculated results and the experimental data, it can be concluded that model proposed can sufficiently describe the performance of the H2S removal. The suitable values of the parameters are as follows: max = 0.0000007 (s1), KS = 0.0000039 (g cm3), kG = 0.0086 (cm s1), HS = 0.9 ((g cm3)/(g cm3)), and Yx/s = 10.