好氧区DO对A/O工艺处理ABS树脂废水的影响

Effect of DO in Aerobic Zone on Treatment of ABS Resin Wastewater by Integrated A/O Process

采用一体式A/O工艺处理ABS树脂废水,研究了在好氧区不同的DO浓度下,对COD、TN及NH+4-N的去除效果,通过三维荧光法分析芳香族类有机物的含量变化,以及采用FISH法测定活性污泥中氨氧化菌和亚硝酸盐氧化菌的数量,分析对NH+4-N去除效果变化的原因。结果表明,在总水力停留时间为36 h、回流比为4时,好氧区DO由5 mg/L降至1 mg/L,系统对COD的去除效果不受影响;随着DO浓度的下降,出水TN和NH+4-N浓度逐渐升高,当好氧区DO降至1 mg/L时,出水TN浓度仍满足一级A排放标准,此时出水NH+4-N升高至7.6 mg/L,不能满足一级A排放标准,但氨氧化菌所占比例并未减小(为7.7%),所以低DO浓度下出水氨氮浓度超标的原因并不是活性污泥中缺少氨氧化菌,而是硝化反应速率过低。最后结合对各污染物的去除效果和曝气量,分析得出好氧区DO在2 mg/L左右为较优的操作条件。

The integrated A/O process was used to treat ABS resin wastewater, and the effect of the dissolved oxygen （DO） in the aerobic zone on the removal efficiencies of COD, TN and NH4^＋ - N was investigated. The concentration variation of the aromatic organic compounds was analyzed by three-dimensional fluorescence spectrometry, and the amount of ammonia oxidizing bacteria and nitrite oxidizing bacteria was measured by fluorescence in situ. hybridization （FISH） technology to find the reason for the change in removal efficiency of NH4^＋ - N. The results showed that when the hydraulic retention time was 36 h, and the reflux ratio was 4, the removal efficiency of COD was relatively stable as the DO decreasedfrom 5 mg/L to 1 mg/L. The concentrations of TN and NH4^＋ - N in the effluent increased with the decrease of the DO. When the DO was 1 mg/L, the concentration of TN in the effluent could meet the first level A criteria specified in the Discharge Standard of PoUutants for Municipal 1Vastewater Treatment Plant （GB 18918-2002）, but the concentration of NH4 -N in the effluent increased to 7.6 mg/L which could not meet the first level A criteria. The amount of ammonia oxidizing bacteria slightly increased to 7.7% when the DO decreased to 1 mg/L. Therefore, the reason for NH4^＋ -N in the effluent exceeding the limit under low DO concentration condition could be the low nitration rate but not the insufficient a- mount of ammonia oxidizing bacteria. Combined with the analysis on the removal efficiencies of pollutants and aeration rate, the optimum DO concentration was determined to be about 2 mg/L.