Ağır metallerin kirlenmiş sedimentten biyoliç yöntemiyle giderilmesinde sulfur konsantrasyonun etkisi

Sunulan çalışmada ağır metallerce kirleniş deniz sedimentinden Cr, Cu, Pb ve Zn metallerinin biyoliç yöntemiyle uzaklaştırılmasında kullanılan sülfür miktarının etkisi araştırılmıştır. Biyoliç prosesinde mikrobiyel aktivite için Acidithiobacillius thiooxidans kullanılmıştır. Yapılan deneylerde bir litrelik erlenler içinde %0.5 (w/v) oranında katı madde (sediment) konsantrasyonuyla çalışılmış ve farklı testlerde %0.25, %0.5, %1, ve %1.5 (w/v) oranında eklenen sülfür miktarıyla deneyler yürütülerek optimum sülfür dozu belirlenmiştir. Biyoliç işleminin sonunda, metallerin toplam çözünmesinin yanı sıra, sedimentte bağlı bulundukları kimyasal dağılım formlarındaki değişim de tespit edilmiştir. pH değerinin neredeyse sabitlendiği 48 günlük biyoliç periyodunun sonunda, tüm metallerde en yüksek çözünürlüğün 0.5% (w/v) oranında sülfür eklenen erlenlerde gerçekleştiği görülmüştür. Daha yüksek oranda eklenen sülfürün biyoliç yönteminde inhibe edici etkisi olduğu, daha az sülfürün ise mikrobiyel aktivite için yeterli olmadığı sonucuna varılmıştır. Ağır metallerin kirli sedimentten giderilme oranı sırasıyla Zn>Cu>Cr>Pb şeklinde tespit edilmiştir.

Anahtar Kelimeler:

mikrobiyal aktiviteler, çökelti, kükürt, ağır metaller, su kirliliği

The effect of sulfur concentration on heavy metals bioleaching from contaminated sediments.

The effects of sulfur amount on the performance of Cr, Cu, Pb, and Zn bioleaching from contaminated sediment by using Acidithiobacillus thiooxidans were evaluated with this study. The remediation of metal-contaminated sediment was conducted in 1 liter bioleaching flasks with 0.5% (w/v) solid content. The sulfur contents of 0.25%, 0.5%, 1%, and 1.5% were added to the flasks in order to find out the optimum dose. In addition to total metal solubilization, the changes of metal concentrations in chemical binding fractions were also detected after the experiments. At the end of 48 days of bioleaching period which the pH values were almost stable, the highest metal solubilization efficiencies were detected with 0.5% sulfur content. Higher concentrations of sulfur were found to be inhibitory to the bioleaching process and 0.25% sulfur content was not sufficient to support the microbial activity. The efficiency of metal solubilization from contaminated sediment in the decreasing order was found as: Zn>Cu>Cr>Pb.

Keywords:

microbial activities, sediment, sulfur, heavy metals, water pollution,

PDF

___

Akinci, G., Guven, D. 2011. Bioleaching of heavy metals contaminated sediment by pure and mixed cultures of Acidithiobacillus spp. Desalination, 268:221-226.
Allen, H.E. 1995. Metal Contaminated Aquatic Sediments. 2nd ed. Michigan: Ann Arbor Press.
Bosecker, K. 1997. Bioleaching: Metal solubilization by microorganisms. FEMS Microbiol. Rev., 20:591-604.
Chen, S.Y., Lin, J.G. 2000. Influence of solid content on bioleaching of heavy metals from contaminated sediment by Thiobacillus spp. J Chem. Technol. Biotechnol., 75:649-656.
Chen, S.Y., Lin, J.G. 2001. Bioleaching of heavy metals from sediment: significance of pH. Chemosphere, 44:1093-1102.
Chen, S.Y., Lin, J.G. 2001. Effect of substrate concentrations on bioleaching of metal-contaminated sediment. J Hazard. Mater., B (28):77-89.
Chen, S.Y., Lin, J.G. 2004. Bioleaching of heavy metals from contaminated sediment by indigenous sulfur-oxidizing bacteria in an air-lift bioreactor:effects of sulfur concentration, Water Res., 38:3205-3214.
Dean, J.R. 2003. Methods for environmental trace analysis. England: John Wiley & Sons Ltd.
DSMZ, 2004. Growth mediums of Thiobacillus spp, World Wide Web electronic publication http://www.dsmz.de/microorganisms/html/media/medium000271.html
Guven, E.D., Akinci, G. 2008. Heavy metals partitioning in the sediments of Izmir Inner Bay, J. Environ. Sci., 20 :413–418.
Guven, D., Akinci, G. 2011. Comparison of acid digestion techniques to determine heavy metals in sediment and soil samples. Gazi University Journal of Science, 24(1): 29-34.
Rauret, G., Lopez-Sanchez, J.F., Sahuquillo, A., Rubio, R., Davidson, C., Ure, A. 1999. Improvement of the BCR three step sequential extraction procedure prior to the certification of new sediment and soil reference materials. J. Environ.Monit, 1:57-61
Seidel, H., Wennrich, R., Hoffman, P., Löser, C. 2005. Effect of different types of elemental sulfur on bioleaching of heavy metals from contaminated sediments. Chemosphere, 62(9): 1444-1453.
Tsai, L.J., Yu, K.C., Chen, S.F., Kung, P.Y., Chang, C.Y., Lin, C.H. 2003. Partitioning variation of heavy metals in contaminated river sediment via bioleaching: effect of sulfur added to total solids ratio. Water Res., 37:4623-4630.
Tsai, L.J., Yu, K.C., Chen, S.F., Kung, P.Y. 2003. Effect of temperature on removal of heavy metals from contaminated river sediments via bioleaching. Water Res., 37: 2449-2457.