Abstract:

To improve the total nitrogen (TN) removal efficiency of membrane bioreactor（MBR）, dissolved oxygen (DO) and aeration on/off time were controlled to study the possibility of total nitrogen removal through short-cut nitrification and denitrification.Membrane fouling was also investigated.At the first stage, the aeration on/off time was 5 min/1 min and DO concentration was controlled at different values.When DO was at 2 mg•L^-1, 3 mg•L^-1, nitrite was accumulated and the removal efficiency of TN was higher than that when DO was 1 mg•L^-1, 4 mg•L^-1.However, the highest removal efficiency of TN was only near 40%.At the second stage, DO was 2 mg•L^-1 and aeration on/off time was controlled.When aeration on/off time was 10 min/5 min, the nitrite accumulation ratio and the removal efficiency of TN were both the highest, and the removal efficiency of TN was near 70%.However, TN removal efficiency was reduced when nitrite concentration was too high (about 6 mg•L^-1).The research showed the possibility of total nitrogen removal through short-cut nitrification and denitrification when DO and aeration on/off time were controlled at appropriate values. And the effect of aeration on/off time was more significant than the DO condition.Membrane fouling deteriorated when DO was either too low (1 mg•L^-1) or too high (4 mg•L^-1); the lower the aeration and the longer the aeration off time was, the worse the membrane fouling became.

摘要：

为了改善膜生物反应器（MBR）的脱氮效果，考察了不同溶解氧浓度(DO)、曝气/停曝时间对MBR工艺实现短程硝化反硝化生物脱氮的可能性以及对膜污染的影响。第一阶段采用5 min/1 min的间歇曝气模式，改变DO，在2、3 mg•L^-1时出现了亚硝酸盐氮的积累，相应的总氮的去除率较1、4 mg•L^-1时高，但最高值仅接近40%。第二阶段DO控制在2 mg•L^-1左右，改变曝气/停曝时间，在10 min/5 min时，亚硝酸盐氮积累率最高，总氮去除率也最高，接近70%;同时发现亚硝酸盐氮的浓度过高（在6 mg•L^-1左右）会降低脱氮效果。说明改变DO与曝气/停曝时间均可实现短程硝化反硝化脱氮，但后者效果更为显著。另外，DO过低（1 mg•L^-1）、过高（4 mg•L^-1）时，膜污染均恶化;曝气率越低，停曝的时间越长，膜污染越严重。