عنوان مقاله [English]
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.