常温限氧条件下SBR反应器中的部分亚硝化研究

常温下(14.1～24.2℃)以二级出水(NH 4-N 30～100 mg/L)为原水,在限氧条件下(DO为0.3～0.4 mg/L)的SBR反应器中研究了适合ANAMMOX工艺进水的部分亚硝化工艺.ANAMMOX反应器进水要求NH 4/NO-2=1/1.31,即仅有一部分氨氮形成亚硝酸盐.研究中通过控制进水碱度,以在线DO趋势线为指示,实现部分亚硝化,最终获得NH 4-N/NO-2-N合适比例的出水.当约57%的氨氮转化为亚硝酸盐时,同等比例的HCO-3/NH 4消耗会导致pH值的自然下降.当pH值下降到一定程度时,氨氧化细菌代谢速率的减小导致了耗氧速率(OUR)的急剧下降,DO趋势线就会出现突跃的特征点(本研究以DO突跃至1.0 mg/L为判别),指示出部分亚硝化反应的终点.试验对30～100 mg/L范围内4种氨氮浓度条件下部分亚硝化的最佳碱度进行了研究.结果表明,本试验中进水碱度与氨氮浓度的比率是影响部分亚硝化工艺出水亚硝化比率(NO-2,NH 4)的重要因素,通过对进水碱度的控制完全可以实现向ANAMMOX反应器提供进水的部分亚硝化工艺.

Partial Nitrification in SBR Under Normal Temperature and Limited Oxygen Condition

Partial nitrification was researched in a SBR reactor under the limited oxygen condition (DO 0.3-0.4 mg/L) and the normal temperature of 14.1-24.2 degrees C to produce the correct influent for ANAMMOX process from secondary wastewater (NH4+ -N 30-100 mg/L). The influent for the ANAMMOX process must be composed of NH4+ and NO2- in a ratio of 1/1.31 and therefore only a partial nitrification of ammonium into nitrite was required. The control of alkalinity and the indication of monitoring profile of DO allowed to achieve this partial nitrification with a final effluent only composed of NH4+ -N and NO2(-) -N at the right stoichiometric ratio. The equal consumption of HCO3- /NH4+ in secondary wastewater resulted in a natural pH decrease when approximately 57% of NH4+ -N was oxidized. When the pH dropped to a certain level, the lowering of the metabolic rate of the ammonium oxidizer would lead to rapid decline of the oxygen uptake rate (OUR) in reactor, and the jump characteristic point (it was distinguished by the jump over 1.0 mg/L of DO value) in the DO profile would emerge, which signalled the end-point of the partial nitrifying. The optimum alkalinity of partial nitrification was studied under 4 concentrations in the range of NH4+ -N 30-100 mg/L of secondary wastewater. The result indicated that the bicarbonate/ammonium ratio was the key factor influencing the nitrification ratio (NO2-/NH4+), and it was absolutely possible to successfully achieve partial nitrification that provided right substrate for ANAMMOX reactor through the control of the alkalinity.