A~2O工艺中的反硝化除磷及其强化

为研究A2O工艺中的反硝化除磷现象及影响因素,采用52.5L的A2O反应器处理实际污水.结果表明:正常运行的A2O工艺中存在反硝化除磷现象,在系统HRT为8h,污泥回流比为70%和内回流比为250%的情况下,A2O系统中缺氧区吸磷占总吸磷量的36%左右,序批试验表明,此时反硝化除磷菌占总除磷菌的35.4%.原水的C/N比越低,反硝化除磷的比例越高,但是过低的C/N比会导致TN去除率低下.将缺氧区和好氧区的容积比从1/1扩大到5/8,延长反硝化除磷反应的时间,TN去除率可从62%提高到70%左右,相比单纯提高内回流比更节能.强化A2O工艺中的反硝化除磷,为传统A2O工艺在处理低C/N比污水时提高脱氮除磷效率提供了一个新思路.

Characteristics of denitrifying phosphorus removal in A~2O process

To investigate the occurrence and characteristics of denitrifying phosphorus removal,a lab-scale A2O reactor with working volume of 52.5 L was employed to treat municipal wastewater. The effects of influent COD/TN ratio and the volume ratio of anoxic zone to aerobic zone on denitrifying phosphorus removal were studied. Results show that 36% of total soluble phosphorus can be removed in the anoxic reactor when the HRT is 8 h,sludge recycle ratio is 70% and internal recycle ratio is 250%. Results of batch experiment show that more than 35.4% of phosphorus accumulating organisms (PAOs) in the A2O system can be denitrified. The ratio of anoxic phosphorus uptake increases with the decrease of influent COD/TN ratio. Denitrifying phosphorus removal can also be enhanced by increasing the ratio of anoxic zone to aerobic zone from 1/1 to 5/8. Meanwhile,the TN removal efficiency is increased from 62% to 70%. It is a more energy-efficient way compared with the increase of internal recycle ratio,which can increase the ratio of anoxic phosphorus uptake. Enhancing the denitrifying phosphorus removal in A2O process is an effective way to enhance biological nutrient removal in treating municipal wastewater with low C/N ratio.