Nitrate bioremediation by Chlorella vulgaris MahboobehTaziki,Mohammad Yazdanbakhsh, HosseinAhmadzadeh* Department of Chemistry,Faculty of Science,FerdowsiUniversity of Mashhad, Mashhad, Iran Nitrate contamination of groundwater is an importantissue whichposes a great danger to human lives[1]. Nitrate may cause gastric cancer by reducing to nitrosamines[2]. In addition, the nitrite reacts with the hemoglobin in blood and converts the hemoglobin into methemoglobinwhich does not carry oxygen to cell tissues[3]. Therefore, removal of nitrate from water resources is a challenging problem.The most common conventional treatment processes are reverse osmosis (RO)[4], ion exchange (IE)[5] and electro-dialysis (ED)[6]. As these methods are relatively costly and produce waste by-products, it is important to find alternatives for nitrate removal[1].Biological methods, such as microalgal treatment, provide a promising strategy for nitrate bioremediation from water resourceswithout secondary pollution. Microalgae consume large amounts of nitrate that are converted into biomass, thereby making these species attractive for pollution reduction of waters. In this study, we used Chlorella vulgaris for nitrate removal using BG11 medium under 4000lux light intensity at 27ºC. This algae species was able to reduce NO3 - from 1500ppm to 52 ppm in 3days. Furthermore, the nitrate removal efficiency of 96% and biomass concentration of 0.87gL-1 were obtained. In addition, the effect of buffer(HEPES) on algal growth and nitrate removal was investigated. The results showed that buffer does notaffect algalgrowth and nitrate removal efficiency. The data showed that Chlorella vulgaris has high capability for Nitrate bioremediation. References: 1. Ghafari, S., M. Hasan, and M.K. Aroua, Bio-electrochemical removal of nitrate from water and wastewater-A review. Bioresource Technology, 2008. 99(10): p. 3965- 3974. 2. Samatya, S., et al., Removal of nitrate from aqueous solution by nitrate selective ion exchange resins. Reactive and Functional Polymers, 2006. 66(11): p. 1206-1214. 3. El Midaoui, A., et al., Optimization of nitrate removal operation from ground water by electrodialysis. Separation and Purification Technology, 2002. 29(3): p. 235-244. 4. Ayyasamy, P.M., et al., Two-stage removal of nitrate from groundwater using biological and chemical treatments. Journal of Bioscience and Bioengineering, 2007. 104(2): p. 129-134. 5. Pintar, A., J. Batista, and J. Levec, Integrated ion exchange/catalytic process for efficient removal of nitrates from drinking water. Chemical Engineering Science, 2001. 56(4): p. 1551-1559. 6. McAdam, E.J. and S.J. Judd, A review of membrane bioreactor potential for nitrate removal from drinking water. Desalination, 2006. 196(1–3): p. 135-148.

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