Optimization of the treatability of landfill leachate by electrocoagulation using Taguchi method

In this study; treatability of landfill leachate (LL) from the landfill site by electrocoagulation (EC) process, which is an electrochemical treatment method, was investigated. EC processes were performed to using Fe-Fe and Al-Al electrod pairs in the separate battch studies. In the study, the optimization of the experimental sets and evaluation of the test results were performed according to the Taguchi Method. The best COD, dissolved COD and color removal efficiencies were calculated from the obtained from batch test results. At which levels the highest pollutant removal efficiencies obtained, was determined according to experimental test results analized using Taguchi Metod Electrocoagulation studies were performed in 3 factors and 5 levels. Independent variables were current density, reaction time and pH. As dependent variables were COD, dissolved COD and color. The experiment matrix generated using the Taguchi Method was constructed according to the orthogonal sequence L25 which is suitable for 3 factor and 5 levels. All studies done were performed according to this matrix. The Taguchi method and ANOVA method were used in the analysis of the experimental results. Taguchi method was used to determine the factors and levels of best pollutant removal efficiency. Morover, ANOVA method was used for variance analysis and the results obtained from experimental studies were tested for conformity to the model. As a result of using aluminum electrodes as anode and cathode; COD, dissolved COD and color removal efficiencies were obtained as 61.53%, 50.83% and 88%, respectively. As a result of the experiments conducted using iron electrodes as anode and cathode; COD, dissolved COD and color removal efficiencies were obtained as 39.19%, 38.81% and 88%, respectively. Electrochemical electric consumption costs for Al and Fe electrodes were calculated as 1,82 $/m3LL and 2,26 $/m3LL, respectively. As a result of the optimization studies carried out the Taguchi method, the best levels of the factors were determined. Studies with Al electrodes, levels obtained the best COD removal efficiency for current density, reaction time and pH were determined as 5, 4 and 2, respectively. These levels for Fe electrodes were obtained as 5, 5 and 1, respectively. For all removal parameters, the most important factor contributing to removal efficiencies was obtained as pH. As a result of ANOVA analysis of the studies performed with Al electrodes, the effects of independent variables (current density, reaction time and pH) on COD removal efficiency were determined as %6,79, %7,87 and %77,79 respectively. As a result of studies with Fe electrodes, the effects of independent variables on COD removal were determined as %5,83, %7,17 ve %81,07, respectively. Keywords: Electrocoagulation, Landfill Leachate Treatment, Taguchi Method, ANOVA.