In a previous project (VR, 2010-2012), we focused on developing synthetic membranes for this goal using cell macro-encapsulation and identifying important characteristics of the membranes used in bioreactors and testing their interaction with digesting microorganisms. It led to successful results, but needs further development which is the subject of this project. In this project, the main objective is finding possible solutions for macro-encapsulations. Two systems will be developed and examined: (a) a membrane bioreactor system using macro-encapsulated cells in form of tea-bags, (b) a membrane bioreactor, in which the cells are packed between two permeable membranes. Furthermore, two types of anaerobic fermentations,i.e. bacterial digestion to biogas and yeast fermentation to ethanol will be examined during the development. However, the concept will be open to be tested for other applications in collaboration with other research groups.