Nitrate Removal from Drinking Water Wells by Heterotrophic Denitrification Using Citric Acid as a Carbon Source and Ozonation

Document Type : Research Paper


1 PhD Student in Environmental Engineering, Faculty of Natural Resources and Environment,Islamic Azad University, Science and Research Branch, Tehran, Iran

2 Prof., Dept. of Environmental Engineering, Faculty of Natural Resources and Environment, Islamic Azad University, Science and Research Branch, Tehran, Iran

3 Assist. Prof., Dept. of Water and Environmental Engineering, Faculty of Civil Engineering, Shahrood University of Technology, Shahrood, Iran


Nitrate removal using biological heterotrophic denitrification is one of the most effective and economical processes to remove nitrate from drinking water. In recent studies, carbon sources such as acetic acid, methanol, ethanol, glucose, etc. have been used as a carbon source for heterotrophic bacteria. Inevitable residues of these carbon sources in effluent water and the cost of them are the key challenges for applying these carbon sources in drinking water, in the operational scales. To overcome these challenges, in this research, citric acid produced from sugar beet is used as a harmless, relatively economical and accessible carbon source. Also, to remove the remaining trace amounts of carbon source in denitrified water and disinfection of treated water, ozonation has been used as a dual-purpose process. Pilot studies of this process during the operation of about one year on natural water of one of the wells of North Khorasan province in Iran with the nitrate concentration of 104±10 ppm ppm as NO3- showed that in four column bioreactor packed with different media such as natural river gravel, polypropylene plastic (PP), polyethylene plastic (PE) and Pumice aggregates and by carbon to nitrogen ratio (C/N) of about stoichiometric amount and HRT of greater than 4 hours and without any other chemical addition, the nitrate removal rate of greater than 85% can be achieved. In the carbon concentrations, about 1.5 times the stoichiometric value and the HRT of about 5 to 7 hours, the removal efficiency can be as high as 95%. Ozonation of treated water in 30 to 60 minutes also showed that the ozone has the capability of the complete removal of carbon residuals in effluent of the process from 15-30 ppm as COD to about zero.


Chang, C. C., Tseng, S. K. & Huang, H. K. 1999. Hydrogenotrophic denitrification with immobilized Alcaligenes eutrophus for drinking water treatment. Bioresource Technology, 69, 53-58.
Cherchi, C., Onnis-Hayden, A., El-Shawabkeh, I. & Gu A. Z. 2009. Implication of using different carbon sources for denitrification in wastewater treatments. Water Environment Research, 81(8), 788-799.
Costa, D. D., Gomes, A. A., Fernandes, M., da casta Bortoluzzi, R. L. Magalhaes, M. D. L. B. & Skoronski, E. 2018. Using natural biomass microorganisms for drinking water denitrification. Journal of Environmental Management, 217, 520-530.
Crittenden, J. C., Trussell, R. R., Hand, D. W., Howe, K. J., Tchobanoglous, G. & Borchardt, J. H. 2012. MWH’s Water Treatment: principles and design, 3rd  Edition, John Wiley & Sons, Hobaken, New Jersey.
Fan, A. M. 2019. Health, exposure and regulatory implications of nitrate and nitrite in drinking water. Encyclopedia of Environmental Health, 417-435.
Ho, C. M., Tseng, S. K. & Chang, Y. J. 2001. Autotrophic denitrification via a novel membrane-attached biofilm reactor. Letters in Applied Microbiology, 33(3), 201-205.
Huang, B., Chi, G., Chen, X. & Shi, Y. 2011. Removal of highly elevated nitrate from drinking water by pH-heterogenized heterotrophic denitrification facilitated with ferrous sulfide-based autotrophic denitrification. Bioresource Technology, 102(2), 10154-10157.
Institute of Standards and Industrial Research of Iran (ISRI), 2010, Drinking water, physical and chemical specification, 5th Edition, No: 1053. (In persian)
Mohseni-Bandpi, A., Elliott, D. J. & Zazouli, M. A. 2013. Biological nitrate removal processes from drinking water supply-a review. Journal of Environmental Health Sciences and Engineering, 11(1), 35.
Reising, A. R. & Schroeder, E. D. 1996. Denitrification incorporating microporous membranes. Journal of Environmental Engineering, 122(7), 599-604.
Rittmann, B. E. & Mccarty, P. L. 2001. Environmental biotechnology: principles and applications, McGraw-Hill, San Francisco, CA.
Sahinkaya, E., Kilic, A. & Duygulu, B. 2014. Pilot and full scale applications of sulfur-based autotrophic denitrification process for nitrate removal from activated sludge process effluent. Water Research, 60,
Temkin, A., Evans, S., Manidi, T., Campbell, C. & Naidenko, O. V. 2019. Exposure-based assessment and economic valuation of adverse birth outcomes and cancer risk due to nitrate in United States drinking water. Environmental Research, 176, 108442.
Upadhyaya, G., Jackson, J., Clancy, T. M., Hyun, S. P., Brown, J., Hayes, K. F., et al. 2010. Simultaneous removal of nitrate and arsenic from drinking water sources utilizing a fixed-bed bioreactor system. Water Research, 44(17), 4958 -4969.
Vagheei, R., Ganjidoust, H., Azimi, A. A. & Ayati, B. 2010a. Treatment of nitrate-contaminated drinking water using autotrophic denitrification in a hydrogenised biofilter. Journal of Water and Wastewater, 73(1), 34-39. (In Persian)
Vagheei, R., Ganjidoust, H., Azimi, A. A. & Ayati, B. 2010b. Nitrate removal from drinking water in a packed-bed bioreactor coupled by a methanol based electrochemical gas generator. Environmental Progress & Sustainable Energy, 29(3), 278-285.
Wang, Z., He, S., Huang, J., Zhou, W. & Chen, W. 2018. Comparison of heterotrophic and autotrophic denitrification processes for nitrate removal from phosphorus-limited surface water. Environmental Pollution, 238, 562-572.
Yang, X., Wang, S. & Zhou, L. 2012. Effect of carbon source, C/N ratio, nitrate and dissolved oxygen concentration on nitrite and ammonium production from denitrification process by Pseudomonas stutzeri D6. Bioresource Technology, 104, 65-72.
Zhang, B., Liu, Y., Tong, S., Zheng, M., Zhao, Y., Tian, C., et al. 2014. Enhancement of bacterial denitrification for nitrate removal in groundwater with electrical stimulation from microbial fuel cells. Journal of Power Sources, 268, 423-429.
Zhang, Y. & Angelidaki, I. 2013. A new method for in situ nitrate removal from groundwater using submerged microbial desalination-dedenitrification cell (SMDDC). Water Research, 47(5), 1827-1836.