S518 Abstracts / Journal of Biotechnology 136S (2008) S506–S518 V7-P-031 Analysis and retrofit design of biological wastewater treatment facilities using process simulation tools Victor Papavasileiou 1,* , Demetri Petrides 2 1 Intelligen Europe, Lage Rijndijk 35A, 2315 JL Leiden, The Netherlands 2 Intelligen, Inc., 2326 Morse Avenue, Scotch Plains, NJ 07076, USA E-mail address: vpapavasileiou@intelligen.com (V. Papavasileiou). Process simulators have been used in the petroleum and chemi- cal industries for over four decades to facilitate the design of new processes and optimize the performance of existing ones. Similar benefits can be derived from the use of such tools in the environ- mental arena, particularly in the field of physical and biological treatment of municipal and industrial wastewater. Specifically, pro- cess simulators can be used to evaluate and improve options for: (1) more efficient removal of nutrients (e.g., organic nitrogen and phosphorous) that cause eutrofication, (2) estimation and control of volatile organic compound (VOC) emissions from open tanks, and (3) more efficient removal and control of hazardous compounds. The potential benefits will be illustrated with case studies involving both municipal and industrial wastewater facilities. doi:10.1016/j.jbiotec.2008.07.654 V7-YP-004 Dissolved oxygen control strategy for efficient fermentative pro- duction of 2,3-butanediol by Klebsiella oxytoca Xiaojun Ji 1 , He Huang 1,2,* , Jun Du 1 , Nan Hu 1,2 , Shuang Li 1,2 1 College of Life Science and Pharmacy, Nanjing University of Technol- ogy, Nanjing 210009, PR China 2 Jiangsu Provincial Innovation Center for Industrial Biotechnology, Nanjing 211816, PR China E-mail address: biotech@njut.edu.cn (H. Huang). 2,3-butanediol (2,3-BD), a potential platform chemical for the pro- duction of various high value-added derivatives, could be produced from carbohydrates by enteric bacteria of the genera Klebsiella via the mixed acid-butanediol fermentation pathway (Syu, 2001). In the previous study, it was found that the dissolved oxygen (DO) concentration was a critical factor for the production of high levels of 2,3-BD. Higher DO concentration mainly leaded to the growth of cells at the expense of 2,3-BD production. While when oxygen was limited, many byproducts such as acetoin, acetic acid, lactic acid and ethanol would be then produced (Converti et al., 2003). The DO con- centration for maximum reactor productivity was different from those for maximizing 2,3-BD yield and final 2,3-BD concentration (Syu, 2001). All this information demonstrates the positive or neg- ative effect of oxygen on 2,3-BD production, but no conclusions can be drawn on the exact nature of the aeration regime. In the present study, the kinetic parameters of batch fermentation processes of Klebsiella oxytoca ME-UD-3 (Ji et al., 2008) at different DO con- centrations were investigated. It was found that the consumption capacity of carbon source increased and the lag stage of cell growth could be shortened with controlling at a higher DO concentration. On the other hand, at the lower DO concentration, the production capability and rate of 2,3-BD were promoted. Subsequently, a two- stage DO control strategy, aimed at achieving high concentration, high yield, and high productivity of 2,3-BD, was designed based on the kinetic analysis of batch processes controlled by single agitation speeds and was confirmed experimentally. Acknowledgements The authors would like to thank the National Natural Science Foun- dation of China, under grant no. 20606018 and National Basic Research Program of China under grant no. 2007CB707805 for financial support. References Converti, A., Perego, P., Borghi, M.D., 2003. Effect of specific oxygen uptake rate on Enterobacter aerogenes energetics: carbon and reduction degree balances in batch cultivations. Biotechnol. Bioeng. 82, 370–377. Ji, X.J., Huang, H., Li, S., Du, J., Lian, M., 2008. Enhanced 2,3-butanediol production by altering the mixed acid fermentation pathway in Klebsiella oxytoca. Biotechnol. Lett. 30, 731–734. Syu, M.J., 2001. Biological production of 2,3-butanediol. Appl. Microbiol. Biotechnol. 55, 10–18. doi:10.1016/j.jbiotec.2008.07.655