Abstract: The present invention relates to “closed loop” processes, systems and compositions for providing one or more flame retardant properties to, or for enhancing one or more flame retardant properties of, substrates containing at least about 5 weight percent of non-thermoplastic material, such as non-thermoplastic filaments, microfibers, fibers, fibrous compositions, threads, yarns, fabrics, textiles, materials, items of apparel, paper, tissue and/or blends, or to one or more products produced using any of the foregoing materials, and to substrates treated in accordance with the processes, systems and/or compositions of the invention.