This book covers all the existing membrane operations from the molecular separation to the reactors to the contactors. The specific potential of these advanced new operations in process engineering is analyzed by different experts in the field for their basic aspects and particularly for their potential application considering process intensification for a sustainable growth and improvement in the quality of life. The role of membrane engineering as a dominant technology in some areas such as water desalination or artificial organs is particularly stressed. Topics such as membranes in fuel cells, membranes in MEMS (microelectromechanical systems) and OLEDS (organic light-emitting diodes), integrated membrane systems, etc. are considered with great attention.