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Struvite Precipitation and Phosphorous Removal from Urine Synthetic Solution: Reaction Kinetic Study

*Marwa Saied Shalaby  -  Chemical Engineering and Pilot Plant Department, National Research Center, El buhouth St., Dokki, Giza 12311,, Egypt
Shadia El-Rafie  -  Chemical Engineering and Pilot Plant Department, National Research Center, El buhouth St., Dokki, Giza 12311,, Egypt

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Phosphorus, like oil, is a non-renewable resource that must be harvested from finite resources in the earth’s crust. An essential element for life, phosphorus is becoming increasingly scarce, contaminated, and difficult to extract. Struvite or magnesium ammonium phosphate (MgNH4PO4.6H2O) is a white, crystalline phosphate mineral that can be used as a bio-available fertilizer. The main objective of this research is to indicate the most important operating parameters affecting struvite precipitation by means of chemical reaction kinetics. The present study explores struvite precipitation by chemical method under different starting molar ratios, pH and SSR. It is shown that an increase of starting Mg: PO4: NH4 with respect to magnesium (1.6:1:1) strongly influences the growth rate of struvite and so the efficiency of the phosphate removal. This was attributed to the effect of magnesium on the struvite solubility product and on the reached supersaturation Super Saturation Ratio at optimum starting molar ratio and pH. It was also shown, by using chemical precipitation method that the determined Super Saturation Ratio (SSR) values of struvite, at 8, 8.5, 9, 9.5 and 10 are 1.314, 4.29, 8.89, 9.87 and 14.89 respectively are close to those presented in the literature for different origins of wastewater streams. The results show that SSR , pH, and starting molar ratio strongly influences the kinetics of precipitation and so phosphorous removal to reach 93% removal percent , 5.95 mg/lit as a minimum PO4 remained in solution, and 7.9 gm precipitated struvite from feed synthetic solution of 750 ml . The product was subjected to chemical analysis by means of EDIX-FTIR, SEM and XRD showing conformity with published literature. First-order kinetics was found to be sufficient to describe the rate data. The rates increased with increasing pH and so SSR and the apparent rate constants for the reaction were determined. © 2015 BCREC UNDIP. All rights reserved

Received: 28th July 2014; Revised: 12nd December 2014; Accepted: 25th December 2014

How to Cite: Shalaby, M.S., El-Rafie, Sh. (2015). Struvite Precipitation and Phosphorous Removal from Urine Synthetic Solution: Reaction Kinetic Study. Bulletin of Chemical Reaction Engineering & Catalysis, 10 (1): 88-97. (doi:10.9767/bcrec.10.1.7172.88-97)


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Keywords: Struvite; Solubility Constant; Reaction Kinetics; Crystallization, Human Urine
Funding: National Research center

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  1. Baimer, P. (2004). Phosphorus recovery – an overview of potentials and possibilities. Water Science Technology, 49(10): 185-190
  2. Ye, Z-L., Chen, S-H., Wang, S-M., Lin, L-F., Yan, Y-J., Zhang, Z-J., Chen, J-S. (2010). Short communication: phosphorus recovery from synthetic swine wastewater by chemical precipitation using response surface method- ology, Journal of Hazardous Material 176 1083-1088
  3. Battistoni, P., Pavan, P., Prisciandaro, M., Cecchi, F. (2000). Struvite Crystallization: A Feasible and Reliable Way to Fix Phosphorus in Anaerobic Supernatants, Water Research 34: 3033-3041
  4. Quintana, M, Sanchez, E., Colmenarejo, M.F., Barrera, J., Gracia, G., Borja, R. (2005). Kinetics of phosphorous removal and Struvite formation by the utilization of by-product of magnesium oxide production, Chemical Engineering Journal 111: 45-52
  5. Gaterell, M.R., Gay, R., Wilson, R., Gochin, R.J., Lester, J. N. (2000). An economic and environmental evaluation of the opportunities for substituting phosphorus recovered from wastewater treatment works in existing UK fertilizer markets, Environmental Technology 21: 1067-1084
  6. Shu, L., Schneider, P., Jegatheesan, V., Johnson, J. (2006). An economic evaluation of phosphorus recovery as struvite from digester supernatant, Bioresource Technology 97: 2211-2216
  7. Donnert, D., Salecker, M. (1999). Elimination of phosphorus from waste water by crystallization, Environmental Technolog 20: 735-742
  8. Parsons, S.A. (2001). Recent scientific and technical developments: Struvite precipitation, Scope Newsletter 41: 15-22
  9. Doyle, J.D., Parsons, S.A. (2002). Struvite formation, control and recovery. Water Research 36: 3925-3940
  10. Le Corre, K.S, Valsami-Jones, E., Hobbs, P., Parsons, S.A. (2007). Kinetics of struvite precipitation: effect of the magnesium dose on induction times and precipitation rates. Environmental Technology 28: 1317-1324. doi: 10.1080/09593332808618891
  11. Rahaman, M.S, Ellis, N., Mavinic, D.S. (2008). Effects of various process parameters on struvite precipitation kinetics and subse- quent determination of rate constants. Water Science Technology 57(5): 647-654. doi: 10.2166/wst.2008.022
  12. Capdevielle, A., Sýkorová, E., Béline, F., Daumer, M.L. (2014). Kinetics of struvite precipitation in synthetic biologically treated swine wastewaters. Environmental Technology 35(9-12): 1250-1262
  13. Grasso, D., Weber, W.J. (1989). Mathematical Interpretation of Aqueous‐phase Ozone Decomposition Rates. Journal of Environmental Engineering, 115(3): 541-559
  14. Moon, Y.H., Kim, J.G., Ahn, J.S., Lee, G.H., Moon, H. (2007). Phosphate removal using sludge from fuller’s earth production, Journal of Hazardous Materials 143(1-2): 41-48
  15. Fogler, H.S. (1986), Elements of Chemical Reaction Engineering, Second Edition, Prentice- Hall, Englewood Cliffs, NJ, USA
  16. Nelson, N.O., Mikkelsen, R.L., Hesterberg, D.L. (2003). Struvite precipitation in anaerobic swine lagoon liquid: effect of pH and Mg:P ratio and determination of rate constants, Bioresource Technology 89: 229-236
  17. Levenspiel, O. (1972). Chemical Reaction Engineering, Wiley, New York
  18. Ali, M.I., Schneider, P.A. (2008). An approach of estimating struvite growth kinetic incorpo- rating thermodynamic and solution chemistry, kinetic and process description, Chemical Engineering Science 63: 3514-3525
  19. Lee, S.H., Yoo, B.H., Kim, S.K., Lim, S.J., Kim, J.Y., Kim, T.H. (2013). Enhancement of struvite purity by redissolution of calcium ions in synthetic wastewaters. Journal of Hazardous Material 261: 29-37
  20. Koutsoukos, P., Amjad, Z., Tomson, M.B., Nancollas, G.H. (1980). Crystallization of calcium phosphates: A constant composition study, Journal of American Chemical Society 27: 1553-1557
  21. Etter, B., Tilley, E., Khadka, R., Udert, K.M. (2011). Low-cost struvite production using source-separated urine in Nepal. Water Research 45: 852-862

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