Denitrification Using Starch/PCL Blends as Solid Carbon Source and Biofilm Carrier

The starch/polycaprolactone (PCL) blends (SPCL5) were prepared by twin-screw extruder. The water absorption and leaching characteristics of SPCL5 were studied, and the feasibility and efficiency also investigated in batch experiment using SPCL5 as carbon source and biofilm carrier simultaneously. The results showed that a high release of DOC was observed during the first 3 d after leaching, and then DOC decreased significantly to 1.31 mg/L. The water absorption of SPCL5 was equilibrated in the 1st d which reached 30.97%. SPCL5 could serve as solid carbon source for denitrification from low C/N nitrate-contaminated water. A high denitrification performance was observed after just 1 d acclimatization. After inoculation, the average denitrification rate of SPCL5 was 0.020 8 mg/(g·h). Hydrodynamic shear force played an important role in denitrification process, The denitrification rate increased by about 100% when the rotating speed increasing from 70 r/min to 140 r/min. A negligible effect on denitrification rate was received when the influent concentration of NO3-N ranged from 15-50 mg/L, and the denitrification was a zero-order reaction. The IR analysis confirmed the biodegradation of starch and PCL in SPCL5 blends.