Abstract
Biological desulfurization is a novel technology for the removal of hydrogen sulfide from some biogas or sour gas, in which there are always a certain amounts of carbon disulfide together with much hydrogen sulfide. Nowadays, carbon disulfide is found to have negative effect on the biological desulfurization, but seldom research is afforded to investigate how carbon disulfide inhibits the process of biological desulfurization. In this paper, we investigated the effect of carbon disulfide both on the growth of Thiobacillus thioparus and the resting cells under various concentrations, including 0.01, 0.05, 0.10, 0.15 and 0.20%. In this process, the rate of the cell growth was characterized by the rate of nitrogen consumption in order to solve the problem that the adsorption of cells to sulfur granules have on the accuracy of biomass test. Under the cell density of 23.92 mg N/L, which is lower than the maximum of cell density 36.13 mg N/L, the average rate of thiosulfate oxidation reached the maximum (26.50 S 2 O 3 2- mg/L-h). Carbon disulfide at titers of 0.01% significantly inhibited the growth of cells, but hardly affected the biological desulfurization of resting cells. Although carbon disulfide at titers of 0.05% had negative effect on the biological desulfurization of resting cells, the effect of inhibition could be relieved by the increased density of resting cells. For the resting cells, the parameters of Michaelis-Menten equation were calculated by the method of Lineweaver-Burk. The V max of biological desulfurization was decreased from 27.93 to 14.0 S 2 O 3 2- mg/L-h, and the K m was increased from 0.264 to 0.884 mM, with the concentration of carbon disulfide rising up from 0.0 to 0.1%. These results show that the growth of cells was sensitive to carbon disulfide, and the resting cells had resistance to the low level of carbon disulfide (0.05%). Thus, the inhibition of carbon disulfide to biological desulfurization should be attributed to T. thioparus growth suppression function. Keywords: Carbon disulfide, bio-desulfurization, inhibition, Thiobacillus thioparus , resting cell, gases purification African Journal of Biotechnology , Vol 13(16), 1739-1744
Highlights
Hydrogen sulfide (H2S) is a highly toxic, corroded and malodor gas, which is a common ingredient in natural gas and biogas (Zhang et al, 2008; Kim et al, 2005)
The carbon disulfide slightly dissolved in the water, little carbon disulfide could obviously inhibit the growth of cells
The sulfur compounds oxidation was not coupled with the growth of T. thioparus, the cells could be considered as enzyme, and the optimal density of resting cell was 20 mg-N/L
Summary
Hydrogen sulfide (H2S) is a highly toxic, corroded and malodor gas, which is a common ingredient in natural gas and biogas (Zhang et al, 2008; Kim et al, 2005). Biological desulfurization is a novel method for the removal of H2S from gases stream by sulfide oxidizing bacteria (SOBs) that have capacity of oxidizing low state sulfur compounds. In the process of biological desulfurization, H2S is firstly adsorbed by alkaline adsorbent, and is oxidized to element sulfur by SOBs under oxygen limitation (Equations 1 to 2). Profiting from the regeneration of hydroxide, the alkaline adsorbents could be recycled (Equation 2). It has been considered as the best alternative of the classic chemical methods for desulfurization, and has perspective application in the fields of the desulfurization of gases, such as natural gas and biogas (Abatzoglou and Boivin, 2009)
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