Abstract:

In view of the problems of insufficient carbon source and low nitrogen removal efficiency for biological treatment of low C/N ratio wastewater, a heterotrophic nitrification-aerobic denitrification strain WUST-7 with low C/N ratio was isolated from the activated sludge of petrochemical wastewater treatment plant. Pseudomonas sp. was identified by morphological observation, physiological and biochemical tests and 16S rDNA sequence analysis. The effects of carbon source type, culture temperature, initial pH and rotation speed on the nitrification characteristics were investigated by single factor experiments. The optimal conditions for heterotrophic nitrification were determined as follows: sodium succinate as carbon source, culture temperature 30－35℃, initial pH 8.0－9.0, rotation speed 150－200r/min. Under the optimal culture conditions for 9h, 90.64 % of ammonia nitrogen with initial concentration of 107.52 mg/L could be removed there was no accumulation of nitrite nitrogen and the nitrate nitrogen content was always lower than 3.5mg/L in the whole process. The removal rate of total nitrogen is up to 88.63%. The experimental results showed that the strain WUST-7 had good simultaneous nitrification and denitrification potential when it used ammonia nitrogen for nitrification and nitrate nitrogen for denitrification.

Key words: waste water, heterotrophic nitrification, aerobic denitrification, low C/N ratio, simultaneous nitrification and denitrification

摘要：

针对生物法处理低C/N比废水存在碳源不足、脱氮效率不高问题，从石化废水处理厂活性污泥中分离得到一株低C/N比异养硝化-好氧反硝化菌株WUST-7。通过形态学观察、生理生化试验和16S rDNA序列分析，鉴定其为假单胞菌属（Pseudomonas sp.）。通过单因素实验，考察碳源种类、培养温度、初始pH和摇床转速对菌株硝化性能的影响，确定最优异养硝化培养条件为：丁二酸钠为碳源、培养温度30～35℃、初始pH8.0～9.0、摇床转速150～200r/min。在最优异养硝化条件下培养9h，可将初始浓度为107.52mg/L的氨氮去除90.64%，并且在整个培养过程中没有亚硝酸盐氮的积累，硝酸盐氮含量也始终低于3.5mg/L，总氮的去除率达88.63%。实验结果表明，菌株WUST-7在利用氨氮进行硝化反应的同时，还可以利用硝酸盐氮进行反硝化，具有良好的同步硝化反硝化潜能。

关键词: 废水, 异养硝化, 好氧反硝化, 低C/N比, 同步硝化反硝化