Partial nitritation and anammox (PN/A) is an energy- and carbon-saving process for nitrogen removal from organic deficient wastewater. However, the PN/A effluent often requires polishing to eliminate the nitrate produced by anammox. Iron as the essential element for living organisms has been tested for nitrate reduction and phosphorus recovery in wastewater treatment processes. Here, we proposed a novel process coupling PN/A with iron-based denitrification for efficiently removing nitrogen and phosphorus in a single reactor. Two laboratory-scale bioreactors were operated under oxygen-limited conditions in parallel. Fe with a dosage of ∼ 27 mg Fe/L-wastewater was continuously dosed in the experimental reactor, with the other serving as a control. Throughout 300 days of operation, the results showed that experimental system always had significantly high removal efficiencies of organic carbon, nitrogen and phosphorus compared with control system. The total nitrogen removal achieved 90.1 ± 1.2 % at the rate of 0.96 ± 0.03 kg N/(m•d) due to the improved activity of ammonia oxidizers, anammox bacteria and denitrifiers and enriched nitrogen conversion pathway (i.e., iron-based autotrophic denitrification) with Fe supplement. The total phosphorus removal was synchronously improved to 80.2 ± 9.1 % mainly driven by the phosphate precipitation with iron. This study provides new insights into achieving high-level nitrogen and phosphorus removal in a single reactor, and deepens our understanding of the improved nutrients removal mechanism mediated by iron.

中文翻译：

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零价铁对一级部分亚硝化和厌氧氨氧化的长期影响


部分亚硝化和厌氧氨氧化（PN/A）是一种节能省碳的工艺，用于从缺乏有机物的废水中脱氮。然而，PN/A 废水通常需要精处理以消除厌氧氨氧化产生的硝酸盐。铁作为生物体的必需元素，已在废水处理过程中进行了硝酸盐还原和磷回收的测试。在这里，我们提出了一种将 PN/A 与铁基反硝化耦合的新工艺，用于在单个反应器中有效去除氮和磷。两个实验室规模的生物反应器在限氧条件下并行运行。在实验反应器中连续投加Fe，剂量为~27 mg Fe/L废水，另一反应器作为对照。在300天的运行过程中，结果表明，与对照系统相比，实验系统对有机碳、氮、磷的去除效率始终显着较高。由于氨氧化菌、厌氧氨氧化菌和反硝化菌活性的提高以及富氮转化途径（即铁基自养反硝化），总氮去除率达到90.1±1.2%，去除率为0.96±0.03kgN/(m•d)。 ）补充铁。总磷去除率同步提高至80.2±9.1%，主要是由于磷酸盐与铁的沉淀作用。这项研究为在单个反应器中实现高水平脱氮除磷提供了新的见解，并加深了我们对铁介导的改进的营养物去除机制的理解。