Biological oxidation of ferrous iron: study of bioreactor efficiency

Abstract

The bio-oxidation of ferrous iron is a potential industrial process for the regeneration of ferric iron in the removal of H 2 S. In the first stage, H 2 S is selectively oxidized to elemental sulfur using ferric sulfate. The ferrous sulfate produced is oxidized to ferric sulfate using Thiobacillus ferrooxidans for recycle and reuse in the process. The aim of the work described here was to investigate continuous oxidation of ferrous iron by immobilized T ferrooxidans and the factors which can directly affect the oxidation rate in order to assess the feasibility of this technique on an industrial scale. An analysis of the evolution of bioreactor performance with time (125 days) was performed in order to assess the feasibility of this technique on an industrial scale. A good oxidation rate was obtained despite the transport problems encountered due to occlusion of the porous support. On the other hand, the toxic effects due to absorption in the ferric solution of one or more compounds from the gas digester were studied using a ferric iron solution from the absorption process. The results indicate the feasibility of the biological system for the regeneration of the ferric-absorbing solution. Finally, a previous study for the design of an industrial bioreactor to regenerate ferric sulfate solutions, used to remove H 2 S from biogas in a wastewatertreatment plant (Jerez de la Frontera, Spain), is introduced. Good biological oxidation performances have been obtained using a pilot plant bioreactor of 500 dm 3 .

Ferrous iron oxidation by foam immobilized Acidithiobacillus ferrooxidans: Experiments and modeling

“…30 The growth in a spongy matrix is controlled by the continuous flow of fluid throughout the particles, since cells subjected to flow field are swept into the effluent. 30,31 Although immobilization of Acidithiobacillus ferrooxidans on PUF has been reported for its superior performance 23,25,32,33 and considered to be suitable for industrial applications, 34 a wider understanding from the perspective of a combined requirement of high cell density both in the broth as well as in the foam and a probe into the factors such as pH which affect the immobilization and oxidation process have not been reported so far.…”

Recuperación de cobre en escorias mediante biolixiviación indirecta

“…En relación a la etapa de biooxidación, el diseño de biorreactores es un tema que está siendo ampliamente estudiado en los últimos años [13][14][15] , por lo que este trabajo se atendrá, fundamentalmente, al apartado de lixiviación férrica. El tipo de biorreactor que da lugar a las mayores productividades, cumpliendo los requisitos antes citados, es el lecho fijo inundado [13] .…”

Hydrogen Sulfide Removal From Petroleum Refinery by ImmobilizedThiobacillus ferrooxidansin Fixed-bed Bioreactor

“…Therefore, the development of new bacteria desulfurization has become a focus in environmental researches.The use of polyurethane foam as a support for the passive immobilization of viable T. f cells has been reported to give good results (Halfmeier et al, 1993b;Mesa et al, 2002;Nemati and Webb, 1999).The polyurethane is macroporous and offers lower diffusion resistance to substrate transfer. For this reason, together with its low cost, polyurethane foam is a suitable support for industrial applications (Mesa et al, 2004). In this article, we study the use of a fixed-bed bioreactor with soft polyurethane foam plastics as the immobilizing carrier, by which the removal rate of H 2 S reached over 99.12% for the acidic gas from oil refineries (with a H 2 S content of 90%).…”

“…Many processes have been developed for the precombustion desulfurization of gaseous fuels (Mesa et al, 2004;Nemati and Webb, 1996). At present, some examples of these methods in the case of the removal of H 2 S gas are physical-chemical treatment, cleaning, adsorption on particle surfaces, and absorption by liquid solvents.…”