Performance studies of alum in waste water treatment

Abstract

In this study, coagulation-flocculation process was used to treat waste water sample collected from Brahmaputra River (Bharulumukh) with alum as coagulant. The experiments conducted with the water sample are chloride ion test, Hardness test, Dissolved oxygen, BOD test, Alkalinity test, iron test, turbidity test and Jar test. Jar test was performed to find the optimum coagulant dosage which was found to be 22ppm from the graph drawn for turbidity versus alum dosage. The results of the waste water characterization showed that the concentration of organic matter expressed by the biochemical oxygen demand was high before the jar test but was low after the experiment was repeated using the result obtained from jar test. Addition of coagulant aids provided higher removal efficiencies. After jar test when all the particulate matter has been settled down due to the addition of alum followed by coagulation and flocculation process, the turbidity test as well as iron test and BOD test were performed to check the effectiveness of the jar test. The difference between the results obtained before and after jar test indicates the effectiveness of the experiment in removal of the biological oxygen demand to an extent.

Keywords:Turbidity, BOD removal, coagulation, flocculation