Optimization of COD Removal from Dairy Plant Effluents Using Natural and Chemical Coagulants

Document Type : Research Paper


1 Former Graduate Student of Chemical Engineering, Shahrood Branch, Islamic Azad University, Shahrood, Iran

2 Assist. Prof. in Department of Chemical Engineering, Qaemshahr Branch, Islamic Azad University, Qaemshahr, Iran

3 Assist. Prof. in Department of Chemical Engineering, Ayatollah Amoli Branch, Islamic Azad University, Amol, Iran


Effluents from dairy plants inactivate the active water ecosystem as a result of reducing their dissolved oxygen content, thereby leading to the loss of aquatic life. The objective of this work was to use coagulants for optimizing the chemical oxygen demand (COD) reduction process employed in treating dairy effluents. An optimized composite formulation comprising natural and synthetic coagulants including pectin, sodium alginate, aluminum sulfate, and iron chloride was prepared and the coagulation temperature required to reduce the intended index was determined. Experiment design was accomplsihed using both the fraction of the full factorial statistical method and the Qualitek-4 software. The signal to noise approach was employed for data analysis. Optimum conditions were achieved at aluminum sulfate, sodium alginate, iron chloride, and pectin concentrations of 1.5, 0.03, 1.5, and 1 g L-1, respectively, as well as a temperature of 30 °C. While the COD reduction efficiency under optimal conditions was estimated to be 28.411%, a COD reduction efficiency of 29% was obtained in experiments under optimal conditions. Variation in iron chloride concentrations was identified to be the factor with the greatest contribution of 35% to reducing the effluent organic load. This is while changes in pectin concentration showed a lower contribution (1.8%) and sodium alginate had only a negligible impact of 8.8%. Finally, changes in aluminum sulfate concentration and coagulation temperature had impacts of 30.8 and 23.3%, respectively, on COD reduction. Compared to chemical coagulants, the natural ones exhibited lower effects on COD removal effiecincy.


Main Subjects

Attouti, S., Bestani, B., Benderdouche, N. & Laurent, D., 2013, "Application of Ulva lactuca and Systoceira stricta algae-based activated carbons to hazardous cationic dyes removal from industrial effluents", Water Research, 47(10), 3375-3388.
Balannec, B., Vourch, M., Rabiller-Baudry, M. & Chaufer, B., 2005, "Comparative study of different nanofiltration and reverse osmosis membranes for dairy effluent treatment by dead-end filtration", Separation Purification Technology, 42(2), 195-200.
Carvalho, F., Prazeres, A. R. & Rivas, J., 2013, "Cheese whey wastewater: Characterization and treatment", Science Total Environment, 445-446, 385-396.
Ganjidoost, H. & Mokhtarani, N., 2002, "Comparison of natural polymers and chemical coagulants in the reduction of organic load of whey", Iranian Journal Polymer Science Technology, 15(2), 75-79. 
Guven, G., Perendeci, A. & Tanyolac, A., 2008, "Electrochemical treatment of deproteinated whey wastewater and optimization of treatment conditions with response surface methodology", Journal Hazardous Materials, 157(1), 69-78.
Jelen, P., 2011, "Whey processing/utilization and products", Encyclopedia Dairy Sciences, 2, 731-737.
Kargi, F. & Uzuncar, S., 2012, "Electro-hydrolysis of cheese whey solution for hydrogen gas production and chemical oxygen demand (COD) removal using photo-voltaic cells (PVC)", International Journal of Hydrogen Energy, 37(21), 15841-15849.
Kargi, F. & Uzuncar, S., 2012, "Simultaneous hydrogen gas formation and COD removal from cheese whey wastewater by electro-hydrolysis", International Journal of Hydrogen Energy, 37(16), 11656-11665.
Lee, C.S., Robinson, J. & Chong, M. F., 2014, "A review on application of flocculants in wastewater treatment", Process Safety Environmental Protection, 92(6), 489-508.
Mehdipoor, M., Dehghani, M.H., Nasseri, S., Nadafi, K. & Mahvi, A.H., 2015, "Efficiency of ozonation and chemical coagulation using aluminum sulfate and ferric chloride for reduction of COD from wastewater of rubber industry", Research Environmental Health, 1(2), 79-84.
Moghtader, M. & Montazeri, N., 2005, "Water quality-determination of the chemical oxygen demand", Iranian National Standard Organization, 12, 5-6.
Nargani, Sh., 2015, "Water quality-determination of the chemical oxygen demand index (St-COD)-Small-scale sealed-Tube method", Iranian National Standard Organization, 5, 2-11.
Ntuli, F., Kuipa, K. P. & Muzenda, E., 2011, "Designing of sampling programs for industrial effluent monitoring", Environmental Science Pollution Research, 18(3), 479-484.
Parmar, K.A., Prajapati, S., Patel, R. & Dabhi, Y. 2011, "Effective use of ferrous sulfate and alum as a coagulant in treatment of dairy industry wastewater", Journal of Engineering & Applied Sciences, 6(9), 42-45.
Patil, Ch. & Hugar, M., 2015, "Treatment of dairy wastewater by natural coagulants", International Research Journal of Engineering & Technology, 2(4), 1120-1125.
Prazeres, A., Carvalho, F. & Rivas, J., 2012, "Cheese whey management: A review", Journal of Environmental Management, 110, 48-68.
Yee Shark, K.P. & Wu, T.Y., 2014, "Coagulation–flocculation treatment of high-strength agro-industrial wastewater using natural Cassia obtusifolia seed gum: Treatment efficiencies and flocs characterization", Chemical Engineering Journal, 256, 293-305.
Zhou, Z., Lin, S., Yue, T. & Lee, T.C., 2014, "Adsorption of food dyes from aqueous solution by glutaraldehyde cross-linked magnetic chitosan nanoparticles", Journal of Food Engineering, 126, 133-141.