The present document contains the results and conclusions about the technical and economic study of membrane technology for the enrichment of biogas produced in sewage treatment plants. The technical study has made it possible to identify membrane technology as a valid process to produce biomethane with sufficient quality for its injection into the gas grid. The economic study has revealed that the use of biomethane for its injection into the grid or for its use as a biofuel is profitable from certain plant capacities and depending on the application. It also includes a review of the legislative framework of biogas and biomethane both at Spain and European level as well as a compilation of the environmental factors and impacts associated with the technology. Based on the results obtained it was possible to know the strengths of membrane technology and opportunities for improvement have been identified. This study will be complemented with the validation of a membrane system at pilot scale; the previous tasks for the development of this pilot are detailed in this document.