Bacterial biofilms are one of the most widely distributed forms of living matter on Earth and they mediate a broad range of biochemical processes in water, natural and synthetic porous media. The onset of a series of social, physical and chemical interactions among the biofilm microorganisms, as mediated by the hydrodynamic actions, trigger a plethora of striking collective properties which cannot be traced back to those of the free-standing bacterial cells. To date, a full comprehension of the life-cycle of biofilms, and its connection to hydrodynamics, is still missing due to the complexity of the systems in play and the broad range of space and time scales involved. The multiscale nature of the problem at hand clearly emerges when considering that the whole life-cycle of a biofilm encompasses multiple (i) time scales, spanning from seconds (attachment) to days/week (growth) and (ii) spatial scales, from fractions of micrometers (i.e. the typical scale at which microorganisms interact) up to decimeters, namely the typical size of a representative elementary volume of natural porous media. Due to non-local interactions among communities competing within porous environments, a deep understanding of the overall process requires to focus on sufficiently large spatio-temporal domains. Indeed, the resort to simplistic models, which cannot simulate environmental heterogeneity, long-term evolution and full hydrodynamic coupling, is ruled out. Moreover, the need to attain technical relevant scales calls for the upscaling of pore-scale phenomena. Such in-depth analysis of biofilms dynamics is crucial to control and optimize many processes of decisive engineering, environmental and industrial relevance. The aim of MOBIOS is to develop a beyond state of the art, high-performance, computational framework with multiscale features to progress towards a deep knowledge of the biofilm evolution in real-scale porous environments as driven by hydrodynamics. High Performance Computing (HPC), needed to reach for the above spatio-temporal domains, will be granted by adopting a novel mesoscale description of each stage of the biofilm evolution. The resulting framework will be tailored to take advantage of the most modern HPC architectures. MOBIOS envisages to develop methodologies to transfer information from the pore level to the spatial scales at which the emerging response of porous media can be relevant to engineered and natural systems. This result will be achieved through the development of ad-hoc upscaling approaches seamlessly integrated with the developed pore-scale solvers, both from a methodological and operational perspective. Many applications of decisive technological and environmental importance are expected to gain substantial benefit from MOBIOS outcomes, from bioremediation to biofouling of synthetic media.