OPTIMISATION OF HIBISCUS SABDARIFFA AS A NATURAL COAGULANT TO TREAT CONGO RED IN WASTEWATER

Abstract

The process of coagulation is commonly practiced in water and wastewater treatment to reduce level of dissolved chemical, turbidity and so on with the usage of coagulant. Aluminium sulphate (alum) is the most commonly used coagulant, however, recent studies show that residual aluminium in drinking water and sludge may induce Alzheimer’s disease and environmental issues. Natural coagulant which is environmental friendly and non-toxic is developed as an alternative to overcome these issues. In this work, Hibiscus Sabdariffa was studied as natural coagulant to treat dye wastewater containing Congo red. The seeds were extracted with different solvent such as distilled water, 0.5 M NaCl and 0.05 M NaOH to extract the coagulation agent. The working parameters were optimised using Response Surface Methodology (RSM). 0.5 M NaCl was found to have highest colour removal of 95.1 % among the solvents. In addition, Hibiscus Sabdariffa seed was found to be an effective coagulant that has 91.2 % colour removal at the optimal working condition of pH 2, 190 mg/L coagulant dosage at 400 ppm of dye concentration. It was also been identified that the performance of natural coagulant is comparable with conventional coagulant, aluminium sulphate with colour removal of 91.2 % and 92.3 % respectively.

Keywords

• Hibiscus Sabdariffa
• Natural coagulant
• Coagulation
• Wastewater treatment.