Minimum membrane area of an emulsion pertraction process for Cr(VI) removal and recovery

The design of an emulsion pertraction membrane (EPM) process for the treatment of wastewater containing hexavalent chromium and its recovery for industrial reuse is presented. EPM is a new technology that combines the efficiency of emulsion liquid membranes with the advantages of using hollow fibber membrane modules. It can selectively remove and concentrate metals from diluted process streams. The total membrane required is minimised, complying with effluent disposal regulations and concentrations levels for Cr(VI) reuse. The algebraic and differential equation system modelling the mass transfer along the membrane modules is presented. The differential equations are discretised using orthogonal collocation on finite elements to solve a non-linear programming problem. An improved process configuration recycling the treated wastewater and eliminating fresh water consumption is presented. The sensitivity of the objective function to emulsion tank volumes and aqueous to organic phases ratio in the emulsion are quantified suggesting further improvements for the industrial application of this cleaner technology.