TREATMENT OF TEXTILE INDUSTRY WASTEWATER USING COMBINED PROCESS OF THERMOLYSIS AND COAGULATION-FLOCCULATION: A COMPARISON BETWEEN THE USE OF MAGNESIUM CHLORIDE COAGULANT AND MAGNESIUM CHLORIDE-ORGANIC HYBRID POLYMER AS COAGULANT

A combined process of thermolysis and coagulation-flocculation was carried out to treat textile industry wastewater. For the coagulation-flocculation process, the use of magnesium chloride (MgCl2) and magnesium chloride-polyethylene oxide (MgCl2-PEO) hybrid polymer as coagulants were compared. The effects of pH and coagulant dosage were varied to obtain optimum colour removal and COD reduction. By using thermolysis alone, 63.1% colour removal and 52.15% COD reduction was achieved. After thermolysis, the wastewater was subjected to coagulation-flocculation using two different coagulants. For both MgCl2 and MgCl2-PEO hybrid polymer, the optimum pH for the process was pH 7. When the MgCl2 coagulant was used, the optimum colour removal and COD reduction obtained were 98.59% and 90.32%, respectively. At pH 7, 99.15% colour removal and 91.94% COD reduction were achieved with the use of the hybrid polymer. The use of the MgCl2-PEO hybrid polymer does not only show better efficiency in colour removal and COD reduction but also requires a lower coagulant dosage. The optimum efficiency of MgCl2-PEO hybrid polymer was obtained at 1000 mg/L while for MgCl2; the optimum coagulant dosage was 1500 mg/L.