Chapter 19: Membrane Separations: from Purifications, Minimisation, Reuse and Recycling to Process Intensification

The separation of molecules to achieve a purification or fractionation is a crucial operation in many industrial processes. Many of the world's major industries including dairy, food and beverage, chemical manufacture and wastewater treatment use membrane separations to achieve this. New developments in membrane materials and membrane configurations are also allowing the range of applications to constantly widen, in the main through increasing the range of tolerable operating conditions and enhancing the selectivity of membranes so that the limiting differences between molecules that can be separated is decreasing. This chapter provides an introduction to both the basics and these new developments in sustainable processing with membranes. It gives an overview of the basic concepts underpinning membrane separations and membrane processes, outlines the main applications of membrane processes in sustainable processing and examines future potential applications currently in development, including the use of membranes in process intensification. Two case studies are outlined in more detail: the use of membrane processes to concentrate dilute organics and biofuels from fermentation broths; and membrane linked tandem chemo and bio catalysed reactions using previously incompatible catalysts. The possibilities of new applications and products produced as a result of these new membranes and processes indicate that the impact of membranes in some process industries is only just being realised. In the near future, membrane processes and their integration with other unit operations have the potential to make a significant impact on the triple bottom line and produce more sustainable processes.