Microalgae are promising biomass feedstock for valuable chemical production and biofuel. Now withstanding the extensive R&D efforts devoted to upscaling of microalgae production in the past decade, the cost and energy demand remain too high. In this connection, significant improvements are needed in multiple steps of downstream processing, particularly in harvesting, dewatering and cell disruption. Functionalized nanomaterials have numerous applications in fields ranging from catalysis, electrode materials, medical diagnosis, drug delivery, environmental remediation and biotechnology. In recent years, nanoparticles with multiple functionalities have emerged, which are capable of combining several unit operations into a single step, e.g. a multifunctional collagen based magnetic nanomaterial has been applied for selective absorption and recovery of oil from spills through external magnetic field. Nanomaterials are increasingly being used in microalgae downstream processing, e.g. for harvesting, lipid extraction or biodiesel conversion. This project aimed to achieve a significant cost reduction by using multifunctional nanomaterials to combine multiple unit operations in downstream processing (harvesting, dewatering and cell disruption) into a single technology. The overall objective of this project was to develop a bio-based and reusable cellulose magnetic hybrid (CMH) nanomaterial that can be used for combining flocculation, cell disruption and dewatering of microalgae. This project integrated several promising recent breakthroughs in nanotechnology for downstream processing of microalgae into a single technology with cellulose magnetic hybrid nanomaterial to decrease the downstream processing costs in a microalgal biorefinery.