Microbial Desulphurization of Turkish Lignites by White Rot Fungi Pınar Aytar, † Mesut S ¸ am,* ,† and Ahmet Çabuk ‡ Department of Biology, Faculty of Arts and Science, Balıkesir UniVersity, Balıkesir, Turkey, and Department of Biology, Faculty of Arts and Science, Eskis ¸ehir Osmangazi UniVersity, 26480 Eskis ¸ehir, Turkey ReceiVed NoVember 6, 2007. ReVised Manuscript ReceiVed December 25, 2007 Biodesulphurization experiments were carried out with Tunçbilek lignite, characterized by high sulfur content (2.59%) by using Trametes Versicolor ATCC 200801 and Phanerochaete chrysosporium ME 446. At fungal biomass studies, the effects of various parameters on fungal desulphurization of coals such as pH, temperature, pulp density, incubation time, and sterilization were investigated for both microorganisms. The maximum desulphurization (40%) was observed after 6 days of incubation at 35 °C for T. Versicolor. The optimum pH was measured at 6, and the agitation rate was fixed at 125 rpm. The pulp density was found as 5% (w/v) for the high extent of desulphurization. Also, calorific value did not change during this experiment. However, the ash and metal contents of coal were eliminated. 1. Introduction Coal is the most important nonrenewable energy source of fossil fuels. Among energy sources, coal has been accepted as a major fuel for centuries owing to the fact that it is widespread, cheap, and reliable. While coal is burnt, its sulfur content combines with oxygen to form sulfur dioxide, which causes both acid rain and pollution. The concentration of this gas needs to be reduce for protection of the environment throughout the world. Many countries have noticed the problems and started to reduce the amount of SO 2 emission through legislation. 1 Microbial metabolism of sulfur compounds is interesting in the coal industry for desulphurization. Biodesulphurization may be taken into account as a biochemical reaction catalyzed by microorganisms concluding in the oxidation and sulfur content being transfered into water soluble compounds such as sulfates. 2 This is one of the other desulphurization methods arousing the most interest. Bioprocesses might have important advantages over the conventional technologies of breakdown or cleaning currently in use, and they may open up the possibility of the economic production of new products. Furthermore, biological methods have simple installations would be much milder than equivalent chemical transformations and low energy consump- tion. In addition to removing pyritic sulfur, this method eliminates organic sulfur which is bound to a matrix with covalent bonds making separation from coal difficult. 3 Low-rank coals which are lignites of Turkey mainly occur in a number of fault-bounded Miocene and Pliocene lacustrine basins in intermontane regions. The Tunçbilek-Domanic basin, which is one of the most productive coal basins of western Anatolia-Turkey, contains a thick and lateral extensive coal bed at the base of the Miocene Tunçbilek formation. 4 Lignite was found to be most convenient coal for microbial desulphurization because of the fact that it is a younger coal than other coal types. The pyrite in lignite is poorly attached to the coal making the bond easy to remove. 5 Biodesulphurization studies of coal have been reported with pure cultures of Thiobacillus ferrooxidans, Thiobacillus thiooxi- dans, 6 Sulfolobus acidocaldarius, 7 and Acidianus brierleyi. 8 Many bacterial organisms including Pseudomonas and Sulfolo- bus species were of great interest in the early success of organic sulfur removal. A new isolated bacterium, Gordonia al- kaniVorans RIPI90A, has been shown to desulphurize both dibenzothiophene (DBT) and DBT-containing hexadecane. 9 The ability to remove both organic and inorganic sulfur has been found in Rhodococcus species, and for this reason, biodesul- phurization processes in a new era have been mostly carried out with these species. Desulphurizing Rhodococcus species 10 include Rhodococcus erytropolis IGTS8, 11 R. erytropolis D-1, 12 R. erytropolis H-2, 13 and Rhodococccus sp. ERCD-1. 14 In spite of the fact that much of sulfur removal from coal has been attempted with various bacteria and little work has * Corresponding author: Tel.: +90 (0266) 612 1000. Fax: +90 (0266) 612 1215. E-mail: msam@balikesir.edu.tr. † Balıkesir University. ‡ Eskis ¸ehir Osmangazi University. (1) Prayuenyong, P.; Songklanakarin, J. Sci. Technol. 2002, 24, 493– 507. (2) Cara, J.; Carbolla, M. T.; Moran, A.; Bonilla, D.; Escolano, O.; Garcia Frutos, F. J. Fuel 2005, 84, 1905–10. (3) Cara, J.; Vargas, M.; Moran, A.; Gomez, E.; Martinez, O.; Garcia Frutos, F. J. Fuel 2006, 85, 1756–62. (4) Karayigit, A.; Celik, Y. Energy Sources 2003, 25, 339–55. (5) Garcia, F.; Blazquez, M. L.; Ganzales, F.; Ballesler, A.; Munoz, J. A. BiorecoVery 1993, 2, 179–94. (6) Silverman, M. J. Bacteriol. 1967, 94, 1046–51. (7) Kargi, F.; Robinson, J. Appl. EnViron. Microbiol. 1985, 44, 878– 83. (8) Larsson, L.; Olsson, G.; Holst, O.; Karlsson, H. Appl. EnViron. Microbiol. 1990, 56, 697–701. (9) Mohebali, G.; Ball, A. S.; Rasekh, B.; Kaytash, A. Enzyme Microbiol. Tech. 2007, 40, 578–84. (10) Bozdemir, T.; Durusoy, T.; Erincin, E.; Yürüm, Y. Fuel 1996, 75, 1596–1600. (11) Zakharyants, A. A.; Murygina, V. P.; Kalyuzhnyi, S. V. Screening of Rhodococcus species revealing desulfurization activity with regard to dibenzothiophene. In Biocatalytic technology and nanotechnology; Zaikov, G. E., Ed.; Nova Science Publishers: New York, 2004; pp 51–58. (12) Izumi, Y.; Ohshiro, T.; Ogino, H.; Hine, Y.; Shimao, M. Appl. EnViron. Microbiol. 1994, 60, 223–26. (13) Ohshiro, T.; Hirata, T.; Izumi, Y. FEMS Microbiol. Lett. 1996, 142, 65–70. (14) Grossman, M. J.; Lee, M. K.; Prince, R. C.; Garrett, K. K.; George, G. N.; Pickering, I. J. Appl. EnViron. Microbiol. 1999, 65, 181–88. Energy & Fuels 2008, 22, 1196–1199 1196 10.1021/ef700664t CCC: $40.75  2008 American Chemical Society Published on Web 02/14/2008