The granular sludge biofilm sequencing batch reactor technology can become a next generation standard for high-rate biological nutrient removal from wastewater. This attractive process innovation based on mobile granular biofilms formed by self-aggregation of microorganisms is slowly penetrating the wastewater treatment market. Whereas full-scale plants are currently designed and installed, the design of operation strategies should rely on advanced understanding of mechanisms of microbial selection and granule formation. Based on five years of research conducted from process to biofilm and microbial scales, we provide an applied methodology towards efficient management of the bacterial resource in granular sludge