The Effects of Mixing Speed and Reaction Time on the Removal of Colour and Turbidity from Alor Pongsu Landfill Using Tin Tetrachloride

The release of landfill leachate to the environment without appropriate treatment creates problems to the surroundings as it might affect the groundwater and surface water sources. The use of divalent and trivalent coagulants, for example, alum and ferric chloride are common in the coagulation and flocculation process of leachate. Still, the application of tetravalent chemicals is relatively scarce. In this study, experiments were carried out to assess the use of tin tetrachloride (SnCl₄) as a potential coagulant in removing the colour and turbidity from the leachate taken from Alor Pongsu landfill site, Kerian, Perak. The effects of mixing speed and reaction time for various coagulant dosages and pH ranges were evaluated using a standard jar test. It was found that 99.5% of turbidity and 98.3% of colour were removed at 1 g/L dosage and an agitation speed of 220 rpm. Also, the mixing time of 3 min was chosen as the best agitation time as removal of 99.3% of turbidity and 98.2% of colour were achieved for the same dosage. The study inferred that the agitation speed and time are two important factors among the different mixing conditions that need to be determined in optimizing the coagulation/flocculation process.