Evaluation of Potential of Activated Locust Bean Pod as a Coagulant for Domestic Sewage Treatment

Abstract

An investigation was carried out on the coagulation potential of the activated locust bean pod in comparison with aluminium sulphate (alum) in the treatment of domestic sewage. The treatments included control culture (water without alum and activated locust bean pod treatment), 3.5 g/L of the activated locust bean pod, 4.5 g/L of the activated locust bean pod and 4.5 g/L of alum. All the treatments were cultured in 16-litre buckets. Physical, chemical and bacteriological properties of domestic sewage were determined before and after the application of the coagulants on a weekly basis. The result showed that 1.14 NTU of turbidity was removed from an initial value of 6.34 NTU using 4.5 g/L of the activated locust bean pod. For the samples treated with 4.5 g/L of alum, turbidity reduced to 0.36 NTU, while 0.46 NTU was removed from the control experiment. pH values show that the pH of the samples decreased from6.83 to 4.05, 6.83 to 6.00and 6.83 to 6.15 for the activated locust bean pod, alum and the control tanks, respectively. The result shows that the activated locust bean pod acidified waste water. The result showed that 3.5 g/L and 4.5 g/L of the activated locust bean pod and alum removed about 0.98% and 1.90% of BOD5, respectively, while BOD5 in the control experiment reduced by 0.26% from the initial value of 6. A significant removal of coliform counts activated locust bean pod was observed. The study shows that the activated locust bean pod can be used in place of alum, which is dependent on the end use of treated water.