Evaluation of Efficiency Nitrate Removal of a Nanofiltration Membrane from Drinking Water under Different Operating Conditions

Document Type : Research Paper

Authors

1 Assoc. Prof., Department of Environmental Engineering, University of Tehran

2 Former Grad. Student of Environmental Engineering, University of Tehran

Abstract

The aim of present work was to investigate effects of the water pressure and ion compound present in water to be treated on nitrate removal efficiency of a nanofiltration membrane. Experiments were performed using sodium salts (NaNO3, Na2SO4, NaF), KNO3, Ca(NO3)2, and Mg(NO3)2 added to tap water. The effects of operating pressures were investigated for a pressure range of 4-10 bars for a nitrate concentration of 150 mg.L-1(NO3-). The effects of concentration levels were studied for the levels 50, 100, 150, 200, 250 and 300 mg.L-1(NO3-). Finally,the effects of anions were investigated for concentration levels of 50, 100, 150, 200 and 250 mg.L-1 of F- and SO42-. The results showed that nitrate removal increased with increasing pressure by up to 8 bars beyond which removal goes steady. Increased nitrate salt concentrations in monovalent salts led to reduced nitrate removal but in divalent salts led to increased nitrate removal. The effect of associated cation on nitrate removal was observed to be higher in the case of NaNO3 compared to KNO3. It was further observed that increasing sulfate ion concentrations reduced nitrate removal while increasing fluoride levels increased nitrate removal.

Keywords


1- Erikson, P. (1988). “Nanofiltration extends the range of membrane filtration.” Environ. Prog., 7 (1), 1-17. 
2- Conlon, W. J., and McCellan, S. A. (1989). “Membrane softening: treatment process comes of age.” J. AWWA, 81(11), 47-51.
3- Fu, P., Ruiz, H., Thompson, K., and Spangenberg, C. (1994). “Selecting membranes for removing NOM and DBP precursures.” J. AWWA, 86 (12), 55-72.
4- Duran, F. E., and Dunkelberger, G. W. (1995). “A comparison of membrane softening on 3 South Floridagroundwaters.” Desalination, 102 (1-3), 27-34.
5- Lo, T., and Sudak, R. G. (1992). “Removing water from a groundwater source.” J. AWWA, 84 (1), 79-87.
6- Berg, P., Hagmeyer, G., and Gimble, R. (1997). “Removal of pesticides and other micropollutants by nanofiltration.” Desalination, 113 (2-3), 205-208.
7- Glucina, K., Alvarez, A., Turner, G., and Laine, J. M. (2000). “Assessment of an integrated membrane system for surface water treatment.” Desalination, 132 (1-3), 73-82. 
8- Boussahel, R., Bouland, S., Moussaoui, K. M., and Montiel, A. (2000). “Removal of pesticide residues in water using the nanofiltration process.” Desalination, 132 (1-3), 205-209.
9- Kiso, Y., Nishimura, Y., and Kitao, T. (2000(.“Rejection properties of non-phenylic pesticides with nanofiltration membranes.” J. Membr. Sci., 171, 229-237.
10- Oh, J. I., Urase, T., Kitawaki, H., Rahman, M. M., and Yamamoto, K. (2000). “Modeling of arsenic rejection considering affinity and steric hindrance effect in nanofiltration.” Water Sci. Technol., 42 (3-4), 73-80.
11- Choi, S., Yun, Z., Hong, S., and Ahn, K. (2001). “The effect of co-existing ions and surface characteristics of nanomembranes on the removal of nitrate and fluoride.” Desalination, 133 (1), 53-64.
 12- Kosutic, K., Novak, I, Sipos, L., and Kunst, B. (2004). “Removal of sulfate and other inorganics from potable water by nanofiltration membranes of characterized porosity.” Separ. Purif. Technol., 37, 177-185.
13- Paugam, L., Taha, S., Dorange, G., Jaouen, P., and Quéméneur, F.(2004). “Mechanism of nitrate ions transfer in nanofiltration depending on pressure, pH, concentration and medium composition.”
J. Membr. Sci., 231 (1-2), 37-46.
14- Santafé-Morose, A., Gozálvez-Zafrilla, J. M., and Lora-García, J.(2005). “Performance of commercial nanofiltration membranes in the removal of nitrate ions.” Desalination, 185 (1-3), 281-287.
15- Bockstedte, M., Kley, A.,Neugebauer, J., Scheffler, M., Xianting, X., and Spencer, H.G.(1997). “Transport of electrolytes through a weak acid nanofiltration membrane: Effects of flux and crossflow velocity interpreted using a fine-porous membrane model.” Desalination, 113(1), 85-93.
16- Ratanatamskul, C., Urase, T., and Yamamoto, K. (1998). “Description of behavior in rejection of pollutants in ultra low pressure nanofiltration.” Water Sci. Technol., 38 (4-5), 453-462.
17- Xu, Y., and Lebrun, R.E. (1999).“Investigation of the solute separation by charged nanofiltration membrane: effect of pH, ionic strength and solute type.” J. Membr. Sci., 158 (1-2), 93-104.
18- Paugam, L., Taha, S., Cabon, J., and Dorange, G. (2002). “Elimination of nitrate ions in drinking waters by nanofiltration.” Desalination, 152, 271- 274.
19- ترابیان، ع.، و شکوهی هرندی، م . (1385). حذف نیترات، سولفات و سختی از آبهای سطحی با نانوفیلتراسیون.مجموعه مقالات هفتمین کنفرانس بین‌المللی عمران (ICCE)، دانشگاه تربیت مدرس، تهران، 523.
20- Wang, D.X., Su, M., Yu, Z.Y., Wang, X.L., Ando, M., and Shintani, T. (2005). “Separation performance of a nanofiltration membrane influenced by species and concentration of ions.” Desalination, 175 (2), 219-225.
21- Paugam, L., Diawara, C. K., Schlumpf, J. P., Jaouen, P., and Quéméneur, F. (2004). “Transfer of monovalent anions and nitrates especially through nanofiltration membranes in brackish water conditions.” Separ. Purif. Technol., 40 (3), 237-242.
22- Bannoud, A.H. (2001). “Elimination of hardness and sulfate content in water by nanofiltration.” Desalination, 137 ( 1-3 ), 133–139.
23- Krieg, H.M., Modise, S.J., Keizer, K., and Neomagus, H.W.J.P. (2004). “Salt rejection in nanofiltration for single and binary salt mixtures in view of sulphate removal.” Desalination, 171(2), 205-215.