In the domain of chemical separation, the pursuit of straightforward and expeditious treatment of multicomponent industrial wastewater has emerged as a prominent trend. However, traditional methods have demonstrated low separation efficiency when dealing with emulsified phosphorus-containing wastewater. In this study, a cellulose membrane was used as the base matrix, and La(OH)? nanoparticles were in-situ grown on it to construct a composite membrane capable of simultaneous phosphorus removal and demulsification. Structural characterization revealed that La（OH）? was uniformly anchored on the fiber surface. The membrane's underwater superoleophobicity and low oil adhesion enabled it to separate various oil-in-water emulsions with an efficiency of 99.2% and a separation flux of 1 210 L/（m2?h）. The membrane exhibited sustained high phosphorus removal and demulsification performance even after ten cycles, providing a scalable and sustainable new approach for the next generation of multicomponent industrial wastewater treatment.