Membrane technology plays more and more a crucial role in the purification of biotechnological products. Integration of membrane based unit operations becomes a trend for ongoing process designs. By this, in addition to the well-established membrane unit operations like microfiltration, ultrafiltration, nanofiltration and reverse osmosis, new membranes, modules and systems were developed in the last years. Herein, the efforts in the area of membrane chromatography should be mentioned as a major research topic. This paper focuses on the state of the art in membrane technology, especially in the field of biotechnology, and on innovative developments in the field of membrane chromatography as well as on process design methods, which are necessary to fulfill the challenges for competitive technologies for the future. To minimize the risk that is inherent in the design of any new process, it is essential to use unit operation models that describe the process behavior accurately. Modeling efforts, which were originally developed for other membrane unit operations, show a great potential for the adaption to new developed membrane technologies.