OPTIMIZATION OF DONNAN DIALYSIS FOR ALUM RECOVERY USING BOX BEHNKEN DESIGN

Abstract

Most potable water treatment plants use aluminium salts as coagulants. This generates a lot of treatment residue which consist of a high amount of aluminium in the residue matrix. Recovery of the alum-coagulant from the potable water treatment for reuse provides direct process and economic advantages. Donnan Dialysis is an ion exchange process that has a proven advantage in coagulant recovery. The commercial application of this process requires bench scale optimization before implementation. In this study, a response surface methodology is applied to the Donnan system. Incorporated with the Box-Behnken experimental matrix, the main and interactional effects of input variables for optimum alum recovery was determined. The Nafion 117 cation exchange membrane was used. Using experimental results, the quadratic statistical module generated was significant with a low P-value (<0.001).  The statistical prediction from experimental results shows that high recoveries of 85-96% can be achieved.