The biotechnological development of purple phototrophic bacteria (PPB) focuses on resource recovery from waste sources, contributing to a circular bioeconomy. PURPLEGAIN aims to create a European network to share information, facilitating technology and knowledge transfer between the academic and industrial sectors, related to PPB applications for resource recovery from organic waste sources. Resource recovery includes wastewater or organic waste, open or closed environments, in single or chain processes. The network associates fundamental-focused and applied-research groups, improving lab-scale technology optimization through mechanistic modeling. It benefits the technology transfer from applied-research groups to industry, considerably improving process design.