Rattana Saelee, Juntima Chungsiriporn, Janya Intamanee, and Charun Bunyakan

pp. 195 - 203

Abstract

This work concerns hydrogen sulfide (H₂S) removal from biogas produced from wastewater of concentrated latex rubber industry (CLRI). H₂S content in the biogas of CLRI is significantly high (i.e., up to 0.77 mol/m³ or 26,000 ppm) due to the use of H₂SO₄ during rubber coagulation process. Attempts to treat biogas with high H₂S have not been found in literature reviews. In this work, a chemical oxidation using an iron-chelated solution catalyzed by Fe(III)EDTA is selected for
the treatment of such high H₂S concentrations. Experiments were performed using an industry-size packed column with diameter and packed height of 0.5 and 0.8 m, respectively. The biogas flow rate and H₂S concentration were in the range of 5.16x10^-3 - 5.61x10^-3 m³/s and 0.35-0.77 mol/m³, respectively. Experimental results indicated that Fe(III)EDTA solution was effective at removing H₂S from biogas with a maximum removal efficiency of 97%. Suitable operating conditions, including Fe(III)EDTA concentration, flow of Fe(III)EDTA and air flow rate were determined. In addition, no side-reaction of Fe(III)
EDTA with methane was found. Thus, chemical oxidation using an iron-chelated solution catalyzed by Fe(III)EDTA is a promising technology for H₂S removal from biogas produced from CLRI or other industries. Finally, a mathematical model of the absorption and the reaction between H₂S and Fe(III)EDTA in a packed column is proposed and verified against the experimental data. The results confirm the potential use of the model to design packed column for H₂S removal from biogas
using absorption coupled with oxidation by Fe(III)EDTA.