Zinc Ion Removal from Wastewater by Electrodialysis

This paper describes a robust design method for separation of zinc ions from a solution using a laboratory electrodialysis (ED) setup. An experimental investigation is presented to determine the optimum configuration of factors for the best performance. In order to optimize the performance, the factors which have the greatest influence have to be identified and their optimum values chosen. In this research, Taguchi method was used initially to plan a minimum number of experiments. An orthogonal array of experiments was used to allow simultaneous variation of several factors and investigation of interactions between them. An L9 orthogonal array (four factors in three levels) was employed to evaluate the effects of factors on response. Ionics membranes with moderate ion exchange capacities were used. The optimal levels determined for the four influential factors are: concentration 1000 ppm, temperature 60 °C, flow rate 0.07 mL/s and voltage 30 V. Comparing results obtained by Asahi glass membranes with those obtained by Ionics membranes, it was found that using a membrane pair with higher Ion Exchange Capacity (IEC) improves the performance. The highest removal percentage was found to be 97.67% and 98.73% for the two types of membranes. Statistical analysis, ANOVA, was then employed to determine the relationship between the experimental conditions and the yield levels.