Removal of Nitrate from Livestock Wastewater Using Composite Carbon Sources of Corncob and Polycaprolactone

• • The composite carbon source YP4 (CC:PCL = 3:2) achieved a nitrate nitrogen removal efficiency of 94.76% in livestock wastewater, demonstrating superior denitrification performance compared to single carbon sources. • • Carbon release from the composite materials followed Fickian diffusion (n < 0.45), ensuring sustained and controlled carbon supply for denitrifying microorganisms, which is critical for long-term reactor operation. • • Effluent ammonia nitrogen from YP4 treatment met the GB 18596-2001 discharge standard, indicating that the composite carbon source does not introduce secondary nitrogen pollution. • • YP4 significantly increased the relative abundance of key denitrifying and polymer-degrading genera (Aeromonas, Novosphingobium, Bacteroides, Clostridium sensu stricto), enhancing microbial community function and process stability.