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Background & Aims of the Study: There are three different types of fibers used in the manufacture of various textile products: cellulose fibers, protein fibers and synthetic fibers. Textile wastewater discharge into the environment leads to irreparable damages. The main purpose of this study was treatment of textile wastewater, using a combined coagulation and dissolved air flotation (DAF) processes, Iran in 2016.

Materials and Methods: This study was an empirical-lab study which the Jar tests and DAF were used in laboratory scale. After determination of the optimal condition of pH and the optimum of concentration of poly-aluminum chloride by Jar test, the effect of the effective parameters including the concentration of the coagulant (10, 20, 30, 40, 60 mg/L), coagulation time (5, 10, 15 and 20 min), flotation time (5, 10, 15 and 20 sec), saturation pressure ( 3, 3.5, 4 and 4,5 atm) and turbidity ( 10, 20 , 30, 40, 60 NTU) on the removal efficiency of COD, BOD₅ and TSS by DAF were studied.

Results: Results of this study showed that the DAF process can treatment COD, BOD₅ and TSS up to85.7%, 80.68% and 95.6%, respectively. The appropriate condition was as follows: pH=6, initial concentration of aniline= 200 mg/L, flocculation time = 10 min, flotation time= 20 sec and the air pressure= 4 atm. Also, this study indicates that the DAF process to conclusion requires a lower dosage of poly-aluminum chloride.