The accumulation of textile wastes, without use, leads to many environmental and economic problems, so they must be recycled and given "smart" properties to be useful in many applied fields. Immobilization of nanoparticles, particularly biosynthesized one, on textile surfaces may provide additional bioactive capabilities, such as antimicrobial and photoprotection due to its distinct properties. Therefore, in this study, CuO-NPs were biosynthesized by Chlorella microalga and immobilized on the surface of Polyester/Cotton (PET/C) blended textile waste modified using cellulase enzymes. Phyco-biosynthesized Chlorella-CuO-NPs were characterized using SEM-EDAX, HRTEM, XRD, FTIR, and whose particles were approximately spherical and nano-sized (<10 nm) and capped with organic compounds of biological origin. Both Chlorella-CuO-NPs and cellulase-modified PET/C textiles loaded with Chlorella-CuO-NPs exhibited antimicrobial activity and UV protection. The modified fabric was applied as a nano-biofilter to reduce the microbial load in wastewater to disinfect it from different pathogens e.g. total coliform bacteria, E. coli and Salmonella (efficiency exceeding 97, 98 and 99.4%, respectively). Recycling textile waste using microbial nanotechnology is an environmentally friendly and cost-effective way to develop smart fabrics for various industrial and applications in the environment.