Abstract Ammonium removal is a key step in wastewater treatment which can be accomplished biologically. An interesting process option for this purpose is coupling partial nitritation with the Anammox process. The goal of the partial nitritation process is to convert half of the ammonium in the influent stream into nitrite, so both can be later converted into dinitrogen gas by the Anammox reaction. To obtain a stable partial nitritation, ammonium oxidizing bacteria (AOB) have to prevail over nitrite oxidizing bacteria (NOB) so as to avoid further conversion of nitrite into nitrate. The dissolved oxygen concentration is a key variable for the functional group selection. In this study, a constrained combination of cascade and feedforward control is proposed for reactors with biomass retention, aimed at suppressing unwanted NOB while keeping a nitrite:ammonium ratio suitable for coupling with Anammox. The master controller, aimed to regulate this effluent ratio, generates the set-point for the dissolved oxygen concentration slave controller. In addition to the cascade controller feedback loop, a feed-forward controller calculates the optimal dissolved oxygen concentration based on the current influent stream flow rate and concentrations. The resulting dissolved oxygen concentration set-point is compared to constraints that guarantee the suppression of NOB and survival of AOB. The proposed control strategy is simple to apply in common wastewater treatment plants with biomass retention. A sensitivity analysis is performed to assess the effect of model parameters uncertainty on the controller constraints and to determine which parameters need to be identified with more precision to avoid instability or poor results. The performance and the effect of the uncertainty of the most sensitive parameters on the proposed control algorithm are assessed through simulation using realistic streams as inputs of the process.

中文翻译：

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级联和前馈约束控制的组合用于稳定部分亚硝化和生物量保留

摘要 氨去除是废水处理中的关键步骤，可以通过生物方法完成。为此，一个有趣的工艺选择是将部分亚硝化与厌氧氨氧化工艺结合起来。部分亚硝化过程的目标是将进水流中一半的铵转化为亚硝酸盐，因此两者都可以通过厌氧氨氧化反应转化为二氮气体。为了获得稳定的部分亚硝化，氨氧化菌（AOB）必须优于亚硝酸盐氧化菌（NOB），以避免亚硝酸盐进一步转化为硝酸盐。溶解氧浓度是官能团选择的关键变量。在这项研究中，针对具有生物量保留功能的反应器提出了级联和前馈控制的受限组合，旨在抑制不需要的 NOB，同时保持亚硝酸盐：铵比适合与 Anammox 偶联。主控制器旨在调节该流出物比率，生成溶解氧浓度从控制器的设定点。除了级联控制器反馈回路外，前馈控制器还可以根据当前进水流的流速和浓度计算最佳溶解氧浓度。将得到的溶解氧浓度设定点与保证抑制 NOB 和 AOB 存活的约束条件进行比较。所提出的控制策略很容易应用于具有生物量保留功能的普通污水处理厂。执行敏感性分析以评估模型参数不确定性对控制器约束的影响，并确定需要更精确地识别哪些参数以避免不稳定或不良结果。最敏感参数的不确定性对所提出的控制算法的性能和影响是通过使用真实流作为过程输入的模拟来评估的。