The growing problems of fossil fuel depletion, planet pollution and increasing human population urgently necessitates a more efficient usage of our natural resources. To that end, the concept of a circular bio-economy has been established, which aims at converting biological waste streams into bio-based products. This conversion can be carried out by microorganisms in a bioprocess in which the cells of these microorganisms can arrange in a biofilm. Recently, a new type of granular biofilm in fermentation has been discovered that can be used for the production of bio-based chemicals and polymers. Although the biofilm has already proven its potential in recent research, little is known about its characteristics and the role of the involved microorganisms. Additionally, the biofilm at present lacks the necessary stability for industrial applications. In this project, we will investigate the role of the microorganisms and their environment on the formation of granular biofilms. The generated knowledge will enable to improve the properties of the biofilm, which is crucial in achieving a stable bioprocess. Subsequently, the improved granular biofilm will be used for simultaneous production of bio-based chemicals and polymers from real wastewaters. As such, the final outcomes of this project will directly promote the future industrial application of fermentative granular technology.