The control of H2S in biogas using iron ores as in situ desulfurizers during anaerobic digestion process

Abstract

In this study, five kinds of iron ores, limonite, hematite, manganese ore, magnetite and lava rock, were used as the in situ desulfurizers in the anaerobic digestion reactors to investigate their effects on controlling H2S in biogas. The results show that the addition of the five iron ores could significantly control the content of H2S in biogas, with the best performance for limonite. As limonite dosages increase (10-60 g/L), the contents of H2S in biogas were evidently decreased in the digesters with different initial sulfate concentrations (0-1000 mg/L). After the anaerobic digestion, the removed sulfur was mostly deposited on the surface of limonite. A possible mechanism of H2S control in biogas by limonite was proposed preliminarily, including adsorption, FeS precipitation, and Fe (III) oxidation. The results demonstrated that limonite was a promising in situ desulfurizer for controlling H2S in biogas with low cost and high efficiency.

Selection of in-situ Desulfurizers for Chicken Manure Biogas and Prediction of Dosage

“…Therefore, adding iron compounds had no significant influence on biogas production in this study. Zhou et al found that adding limonite had different impacts on biogas production with different initial concentrations of sulfate, which might be due to the changes of microbial quantity and activity under different conditions [6].…”

“…When FeSO 4 was applied, the desulfurization effect seemed normal in the early stage of fermentation, but later the H 2 S concentration increased sharply -far higher than that of control (up to 9,000 ppmv). This indicated that the added SO 4 2-got involved in the microbial reaction process, employed by sulfate-reducing bacteria as an electron acceptor to generate H 2 S [6,15]. Therefore, FeSO 4 was not suitable for in-situ desulfurization use.…”

“…In the microscopic mechanism, a process of insitu desulfurization will include the competition and collaboration of microorganisms, reactions of sulfur and iron, etc. [6,16]. But for the prediction of desulfurizer dosage, this simple and practical method can be applied regardless of the complex principles.…”

“…This desulphurization method has the advantages of simple operation, small investment, and good desulphurization rate. Five kinds of natural iron ores were used as in-situ desulfurizers during the anaerobic digestion of waste-activated sludge, and limonite showed high desulfurization efficiency [6]. Besides being used as H 2 S control in anaerobic fermenters, iron compounds have been widely used for the abatement of sulfide-associated problems in sewer systems [7][8].…”

Effect of Aso limonite on anaerobic digestion of waste sewage sludge

“…However, hydrogen sulfide and ammonia which are basically produced as by-products during the anaerobic digestion of WSS has a corrosive effect on the fermentation tank ). In addition, these odorous gases are harmful to humans through direct irritations or psychopathologic mechanisms (Schiffman and Williams 2005) and have a negative impact on methane fermentation as a high concentration of hydrogen sulfide lowers the quality of biogas production (Zhou et al 2016) as well as the ammonia triggers to accumulate the organic acids (Wu et al 2016). Therefore, the removal of hydrogen sulfide and ammonia during the anaerobic digestion of WSS is essential to the long-term operation of anaerobic digestion (Dai et al 2017).…”