以FA与FNA为控制因子的短程硝化启动与维持

Start Up and Maintain of Nitritation by the Inhibition of FA and FNA

为了实现污泥消化液旁侧脱氮,降低主处理区进水氮负荷,试验采用A/O工艺研究消化污泥脱水液短程硝化启动与维持,在常温、长SRT、较高DO条件下,逐步提高进水ALR(以N计)从0.23 kg/(m3.d)到0.78 kg/(m3.d),强化FA对NOB的抑制作用,成功启动了短程硝化.针对废水碱度不足的水质特征,利用FA与FNA的联合抑制使短程硝化得到稳定维持,在稳定运行的30 d内NO2--N积累率一直保持在90%以上.在此期间反应器平均DO浓度一直保持在2 mg/L以上,即使平均DO浓度提高到4.8 mg/L左右,也未出现NO2--N积累率降低,说明利用上述手段维持的短程硝化具有抵抗高DO冲击能力.通过降低进水ALR,导致反应器后段FNA浓度增加,强化了FNA的抑制作用,虽然FA的抑制作用降低,短程硝化仍然连续运行达2个月,当反应器后段FNA的抑制作用撤除后,短程硝化在3 d后被彻底破坏,充分证明了FNA对NOB抑制作用及其对维持本系统短程硝化所起的重要作用.

In order to treat the digested sludge dewatering liquor bypass and reduce influent ALR of wastewater treatment plant, the startup and maintenance of nitritation was investigated in an A/O reactor. NOB activity was inhibited and nitritation was stated up successfully by increasing the influent ALR （in N, the same below） step by step from 0.23 kg/（m3 ＂d） to 0.78 kg/（m3 ＂d）, in spite of normal temperature, long SRT and high DO concentration. Due to the deficiency of alkalinity in influent, nitritation could be maintained steadily by the associated inhibition of free ammonia （FA） and free nitrous acid （FNA）. The nitrite accumulation ratio always kept at above 90% during the period of maintaining nitritation for 30 days, and correspondingly the average concentration of DO was higher than 2 mg/L. The nitrite accumulation ratio did not decline even if the average DO concentration increased to 4.8 mg/L, which demonstrated that high DO could not destroy the nitritation built by the associated inhibition of FA and FNA. The concentration of FNA at the last chambers was increased by reducing the influent ALR in order to enhance the inhibition of FNA. The nitritation was still maintained for two months although the inhibition of FA was weakened. But the nitritation was destroyed completely in 3 days after the inhibition of FNA was eliminated, which showed the inhibition of FNA to NOB was very critical to maintain steadily nitritation.