In order to overcome the shortcoming of poor hydrophilicity and smooth surface of carbon fiber, and to improve water treatment effect of biofilm system using carbon fiber as support, this paper employed nitric acid and ferrous oxalate to modify carbon fiber. A series tests were conducted on untreated carbon fiber, nitric acid oxidized carbon fiber, nitric acid and ferrous oxalate modified carbon fiber, namely, scanning electron microscopy-energy dispersive spectrometer, X-ray photoelectron spectroscopy, static contact angle and water treatment effect. Results showed that, hydrophilic functional group containing oxygen and nitrogen on the surface of carbon fiber increased after modification by nitric acid and ferrous oxalate, which greatly improved the hydrophilicity of carbon fiber surface. The ferrum element in ferrous oxalate modified carbon fiber existed in the form of magnetic oxide (Fe₃O₄) via FeOC to bond with carbon fiber, which noticeably enhanced the surface roughness of carbon fiber. Dry weight of biofilm per unit immobilized on ferrous oxalate modified carbon fiber support enhanced and it was 2.3 and 0.6 times bigger than that of untreated and nitric acid oxidized carbon fiber. Biofilm system with ferrous oxalate modified carbon fiber as support had better water treatment effect and stable effluent standard. The average removal efficiency of chemical oxygen demand, ammonia nitrogen and total phosphorus achieved 97%, 96% and 97%. In addition, removal efficiency of chemical oxygen demand, ammonia nitrogen and total phosphorus increased by 7.18%, 10.30%, 9.40% and 4.86%, 4.30%, 6.40%, compared to carbon fiber and nitric acid oxidized carbon fiber support biofilm system. Combination of nitric acid oxidation and ferrous oxalate deposition, which has never been developed before, is a promising carbon fiber surface modification method to improve its performance as biofilm support.

为了克服碳纤维亲水性差，表面光滑的缺点，提高以碳纤维为载体的生物膜系统的水处理效果，本文采用硝酸和草酸亚铁对碳纤维进行了改性。对未处理的碳纤维，硝酸氧化的碳纤维，硝酸和草酸亚铁改性的碳纤维进行了一系列测试，即扫描电子显微镜-能量色散光谱仪，X射线光电子能谱，静态接触角和水处理效果。结果表明，硝酸和草酸亚铁改性后，碳纤维表面含氧，氮的亲水性官能团增加，大大提高了碳纤维表面的亲水性。₃ O ₄）通过Fe OC与碳纤维结合，这显着提高了碳纤维的表面粗糙度。固定在草酸亚铁改性的碳纤维载体上的每单位生物膜的干重增加，比未处理和硝酸氧化的碳纤维大2.3倍和0.6倍。以草酸亚铁改性碳纤维为载体的生物膜系统具有较好的水处理效果和稳定的出水标准。化学需氧量，氨氮和总磷的平均去除率分别达到97％，96％和97％。此外，与碳纤维和硝酸氧化碳纤维支持生物膜系统相比，化学需氧量，氨氮和总磷的去除效率分别提高了7.18％，10.30％，9.40％和4.86％，4.30％，6.40％。硝酸氧化与草酸亚铁沉积相结合，