Abstract: Ciprofloxacin (CIP), a widely utilized antibiotic in livestock farming, poses substantial risks to both ecosystem stability and food safety. Currently, peroxymonosulfate (PMS)-based advanced oxidation processes (AOPs) can effectively degrade CIP by generating multiple reactive radicals (e.g., SO_−4· and ·OH). However, there are still some problems such as insufficient active sites and difficulty in recovery Notably, fir sawdust biochar (BC) serves as an eco-functional material. Through simple nitrogen doping, its carbon network structure is significantly optimized, which accelerates electron transfer efficiency and enhances peroxymonosulfate (PMS) activation performance. A synergistic "adsorption-catalysis" strategy was proposed in this study, where recyclable sponge-immobilized nitrogen-doped biochar composites (Sponge@NC) were constructed through nitrogen modification of waste fir sawdust-derived biochar followed by 3D sponge carrier integration. The peroxymonosulfate (PMS) activation mechanisms and ciprofloxacin (CIP) degradation performance were systematically elucidated, demonstrating enhanced interfacial electron transfer and catalytic durability. This material overcomes the inherent limitations of conventional powdered catalysts. The sponge carrier not only enables efficient recovery of biochar but also promotes pollutant enrichment and radical generation through its hierarchically porous architecture, while simultaneously establishing interfacial synergistic effects within the composite system. Under the conditions of 10 mg/L CIP, 50 mm PMS, and pH 8, the Sponge@NC system achieved approximately 80% degradation efficiency within 180 min. Quenching experiments and electron paramagnetic resonance (EPR) analysis confirmed that hydroxyl radicals (·OH) and superoxide radicals (O_−2·) served as the dominant reactive oxygen species (ROS) responsible for CIP degradation. This study provides critical insights into practical antibiotic remediation in livestock wastewater.