不同固体碳源释碳特征及其对反硝化脱氮效果研究

碳源是低碳氮比废水反硝化过程的限制性因素之一,外加固体碳源可以强化微生物反硝化脱氮效果。为筛选出合适的外加碳源,本研究选用廉价的农业废弃物(稻草和锯木屑)和水生植物(绿狐尾藻和梭鱼草)作为固体碳源材料,分析不同固体碳源材料的释碳特征,比较其对反硝化过程的脱氮效果。结果表明,4种材料的释碳过程均符合二级动力学方程,其释碳能力大小为:稻草(25.64 mg/(g·L))梭鱼草(23.64 mg/(g·L))锯木屑(22.37 mg/(g·L))绿狐尾藻(20.45 mg/(g·L)),其中,绿狐尾藻的释放速率最快,其COD释放浓度达饱和浓度一半时所用时间仅为3.56 h。4种材料作为外加固体碳源可显著提高反硝化脱氮效率,其对水体硝态氮的去除率均达80%以上。由于梭鱼草在试验后期出现氨氮的大量积累,会造成水体二次污染。因此,稻草、锯木屑和绿狐尾藻适合作为外加碳源材料利用。

Study on carbon release characteristics and denitrification performance of different solid carbon sources

Carbon source is one of the limiting factors in denitrification process of low C/N ratio wastewater, while the addition of solid carbon source can enhance the microbial denitrification. In order to screen out suitable external carbon sources, this study selected cheap agricultural waste (straw and sawdust) and aquatic plants (Myriophyllum aquaticum and Pontederia cordata) as solid carbon sources, analyzed the carbon release characteristics of different solid carbon sources, and compared their nitrogen removal efficiency in the denitrification process. Results showed that the carbon release processes of four study materials all complied with the second-order kinetic equation, and their carbon release capacity was as follows: straw (25.64 mg/(g·L)) >P. cordata (23.64 mg/(g·L)) > sawdust (22.37 mg/(g·L)) > M. aquaticum (20.45 mg/(g·L)). Among the four materials, the release rate of M. aquaticum was the fastest, and the release time of its COD was only 3.56 h when its COD reached half the saturated concentration. The denitrification efficiency of the four materials as external solid carbon sources could be significantly improved, and the nitrate nitrogen removal efficiency of the four materials all reached more than 80%. Due to the large accumulation of ammonia nitrogen in the later stage of the experiment, P. cordata as solid carbon source will cause secondary water pollution. Therefore, straw, sawdust and M. aquaticum are suitable for the utilization as additional carbon source materials.