Optimization of Coagulation-Flocculation Process of Landfill Leachate by Tin (IV) Chloride Using Response Surface Methodology

Landfill leachate is highly polluted and generated as a result of water infiltration through solid waste produced domestically and industrially. This study investigated the applicability of the response surface methodology (RSM) to optimize the removal performances of chemical oxygen demand (COD), color, and suspended solids (SS) from landfill leachate by coagulation process using Tin tetrachloride pentahydrate. The leachate samples were collected from Alor Pongsu Landfill (APLS) in Perak, Malaysia. Before starting the experiments, general characterization was carried out for raw leachate samples to investigate their physical and chemical properties. The effects of the dosage and pH of SnCl۴ on the removal performances were evaluated as well. An ideal experimental design was performed based on the central composite design (CCD) by RSM. In addition, this RSM was used to evaluate the effects of process variables and their interaction toward the attainment of their optimum conditions. The statistical design of the experiments and data analysis was resolved using the Design-Expert software. Further, the range of coagulant dosage and pH was selected based on a batch study which was conducted at ۱۳ ۰۰۰ mg/L to ۱۷ ۰۰۰ mg/L of SnCl۴ and pH ranged from ۶ to ۱۰. The results showed that the optimum pH and dosage of SnCl۴ were ۷.۱۷ and ۱۵ g/L, respectively, where the maximum removal efficiency was ۶۷.۷% for COD and ۱۰۰% for color and SS. The results were in agreement with the experimental data with a maximum removal efficiency of ۶۷.۸۴ %, ۹۸.۶ %, and ۹۹.۳%, for COD, color, and SS, respectively. Overall, this study verified that the RSM method was viable for optimizing the operational condition of the coagulation-flocculation process.

Keywords:

Landfill , Leachate , Tin tetrachloride , Coagulation , Flocculation , RSM