亚硝酸盐对A2O系统脱氮除磷的影响

在A2O系统中,通过分别向缺氧区和好氧区投加亚硝酸盐的方式,考察和分析了亚硝酸盐的存在对系统脱氮除磷性能的影响.结果表明,系统的硝化、反硝化及除磷性能均对亚硝酸盐的存在比较敏感.亚硝酸盐存在于好氧段时对硝化性能的影响较大,当好氧段亚硝酸盐浓度达到25mg/L时,系统硝化速率仅有5.26mg/(L·h).亚硝酸盐存在于缺氧段时对反硝化性能的抑制作用较大,且当亚硝酸盐长期存在于缺氧段时,系统的反硝化速率降低至11.83mg/(L·h),与正常情况相比下降了60%;亚硝酸盐存在于好氧段时会严重抑制聚磷菌的吸磷能力,系统磷去除率仅有22%.当亚硝酸盐存在于缺氧段时,会引发系统的污泥膨胀问题,导致聚磷菌流失,聚磷菌数量减少到2.02%左右,继而引发系统除磷效果严重恶化.

Effect of nitrite on nutrient removal in A2O system

Experiment operated through dosing nitrite to aerobic and anoxic conditions respectively in A2O system. Effect of nitrite on nitrogen and phosphorus removal was analyzed. Results showed that nitrification, denitrification and phosphorus removal performance of the system were more sensitive to the presence of nitrite.Nitrite existed in aerobic period had more influence on the performance of nitrification, when nitrite concentration in aerobic period reached to 25mg/L, nitrification rate of the system was only 5.26mg/(L·h). Nitrite existed in anoxic period had more inhibition on denitrification performance, when nitrite existed in anoxic period for long time, denitrification rate of the system down to 11.83mg/(L·h) that fall by 60% compared with normal condition. Nitrite existed in aerobic period could inhibit the phosphorus absorption ability of phosphorus-accumulating bacteria seriously with phosphorus removal rate of the system was only 22%; When nitrite existed in anoxic period, it could cause sludge bulking problem in the system, lead to the loss of phosphorus-accumulating bacteria, the number of phosphorus-accumulating bacteria decreased to about 2.02%, which in turn trigger phosphorus removal performance deteriorated seriously.