COD Removal Prediction of DAF Unit Refinery Wastewater by Using Neuro- Fuzzy Systems (ANFIS) (Short Communication)


1 Chemical Engineering Department, Faculty of Engineering, Razi University, Kermanshah, Iran

2 Mechanics of Agricultural Machinary Department, Faculty of Agriculture, Razi University, Kermanshah, Iran


In this study the Dissolved Air Flotation (DAF) system in oil refinery was investigated for the treatment of refinery wastewater. In order to investigate sytem a labratory scale rig was built. The aim is to remove some of the wastewater pollutant materials and data modeling of COD test.The effect of several parameters on flotation efficiency namely, saturator pressure, and coagulant dose, on COD removal was examined experimentally. Experiments  were done by using poly aluminum chloride coagulant (PAC) at pressures 2bar up to 5bar and in three doses 15mg/l، 20mg/l and 25mg/l. After final examination's removal efficiency obtained is close to the performance achieved by the refinery. The data obtained from COD experiments using neuro-fuzzy systems have been  modeled. The correlation coefficient (R2), root mean square error (RMSE) and sum of square error (SSE) of predicted values by using neuro-fuzzy systems are obtained 0.9991, 6.35×10-3and 4.04×10-5 respectively, which shows the high accuracy of neuro-fuzzy systems.


[1] Casey, T.J. (1997). Unit Treatment Processes in Water and Wastewater Engineering. John Wiley& Sons.

[2] Degremont, (1991). Water Treatment Handbook. 6th. Ed.

[3] Casey, T.J. and Naoum, I.E. (1986). Water supply.  John Willey & Sons, England, pp. 69- 82.

[4] Zouboulis,  A.I.  and  Avranas,  A.  (2000).  “Treatment  of  oil  in  water  emulsions  by coagulation and dissolved air flotation.” Colloid. Surface., Vol. 172, pp. 153-161.

[5] Al-Shamrani, A.A., James, A. and Xiao, H. (2002). “Destabilization of oil-water emulsions and separation by dissolved air flotation.” Water Res., Vol. 36, pp. 1503-1512.

[6] Shawwa, A.R. and Smith, D.W. (2000). “Dissolved air flotation model for drinking water treatment.” Can. J. Civ. Eng, Vol. 27, pp. 373-382.

[7] Al-shamrani, A.A., James, A. and Xiao, H. (2002). “Separation of oil from water  by dissolved air flotation.” Colloid. Surface., Vol. 209, pp. 15-26.

[8]  Haarhoff, J.  and  Bezuidenhout, E.  (1999).  “Full  scale  evaluation if activated  sludge thickening by dissolved air flotation.” Water SA., Vol. 25, pp. 153-166.

[9]  Zabel,  T.  and  Ives,  K.G.  (1984).  The  scientific  basis  of  flotation. Martinus  Nijhof publishers.

[10] Hyde, R.A., Miller, D.G., Packham, R.F., and Richards, W.N. (1977). “Evaluation  of dissolved air flotation saturator performance.” JAWWA, Vol. 69, pp. 365-372.

[11] Chung, Y., CHOI, Y.C., CHOI, Y.H. and Kang, H.S. (2000). “A demonstration scaling up of the dissolved air flotation.” Water Res., Vol. 34, pp. 817-824.

[12] Lundh, M., Jonsson, L. and Dahlquist, J. (2000). “Experimental studies of the  fluid dynamics in the separation zone in dissolved air flotation.” Water Resour., Vol. 34, pp. 21- 30.

[13] Ramirez, F.P. and Cortes, M.E. (2004). “The demonstration of residence times in a pilot plant.” Nuc. instrum. methods, Vol. 213, pp. 144-148.

[14] Tansel, B., and Pascual, B. (2004). “Factorial evaluation of operational variables of a DAF process to improve PHC removal efficiency.” Desalination, Vol. 169, pp. 1-10.

[15] Parker, W.J. and Monteith, H.D. (1996). “Stripping of VOC's from dissolved air flotation.” Environ.  prog., Vol. 15, pp. 73-81.

[16] Boyd, J.L., Shell, G.L. and Dahlstrom, D.A. (1971). “Treatment of oily wastewater to meet regulatory standards.” in: AIChE Conf., Toledo.

[17] Miskovic, D., Dalmacija, B., Zivanov, Z., Karlovic, E., Hain, Z. and Maric, S.  (1986). “An Investigation of the Treatment and Recycling of Oil Refinery Wastewater.” Water Sci. Technol., Vol. 18, pp. 105–114.

[18] Moursy, A.S. and Abo-Elela, S.I. (1982). “Treatment of oily refinery wastes using  a dissolved air flotation.” Environ. Int., Vol. 7, pp. 267–270.

[19] Geethanjali, M. and Slochanal, S.M.R. (2008). “A combined adaptive network and fuzzy inference system (ANFIS) approach for overcurrent relay system.” Neuro comput., Vol. 71, pp. 895-903.

[20] Mahanta, C. and Buragohain, M. (2008). “A novel approach for ANFIS modelling based on full factorial design.” Appl. Soft Comput., Vol. 8, pp. 609-625.

[21] Singh, R., Kainthola, A. and Singh,  T.N. (2012). “Estimation  of  elastic  constant   of rocks  using an ANFIS  approach.” Appl. Soft Comput., Vol. 12, pp. 40-45.

[22] Lenore,  S.C.,  Arnold,  E.G.    and  Andrew,  D.E.  (1999).  Standard Methods for the Examination of Water and Wastewater. American Public Health Association, Washington, D.C,USA.

[23] Luthy, R.G., Selleck, R.E. and Galloway, T.R. (1978). “Removal of Emulsified Oil with Organic Coagulants and Dissolved Air Flotation.” J. Water Poll. Cont. Fed., Vol. 50, pp. 331-346.

[24] Rykaart, E.M. and Haarhoff, J. (1995). “Behavior of air injection nozzles in dissolved air flotation.” Water Sci. Technol., Vol. 31, pp. 25-35.

[25] De Rijk, S.E., Van der Graaf, J.H.J.M. and Den Blanken, J.G. (1994). “Bubble size  in flotation thickening.” Water Res., Vol. 28, pp. 465-473.

[26] Edzwald, J.K., Walsh, J.P., Kaminski, G.S. and Dunn, H.J. (1992). “Flocculation and Air Requirements for Dissolved Air Flotation.” JAWWA, Vol. 3, pp. 92-100.

[27]  Edzwald,  J.K.  (1995).  “Principles  and  applications  of  dissolved air  flotation.”  In: Flotation processes in water and sludge treatment. Ives, K. J. & Bernhardt, H. J. (Eds).   , Water Sci. Technol. Great Britain, Vol. 31, pp. 1-23.

[28] Bratby, J. and Marais, G.V.R. (1975). “Saturator performance in Dissolved- Air (pressure)