Application of the deammonification process to mainstream wastewater promises energy-efficient nitrogen removal, but has been limited by unwanted activity of nitrite oxidizing bacteria and low anammox activity at moderate temperatures (<20 °C). In the present study, N removal in a mainstream integrated fixed-film activated sludge (IFAS) deammonification process increased by 27% to 73% total inorganic nitrogen (TIN) removal by diverting 10% of the primary effluent flow around the A-stage and directly into the deammonification reactor, thereby increasing the influent C : N ratio from 2.3 to 3.1 g sCOD/g NH₄⁺-N. This change coincided with a dramatic shift in nitrification activity from the biofilm to the suspension, and the increased carbon enabled a higher suspended solids concentration at a realistic solids retention time of 7.3 ± 2.1 days. Anammox biomass and activity was retained over the entire study (>3 years) and was not negatively impacted by the increase in influent carbon. N isotope testing indicated that cross feeding between denitrifiers and anammox played an important role in N removal and that about 53% of N removal was ultimately routed through the anammox metabolism. The reactor temperature was controlled near 20 °C for most of the study, and 72% TIN removal was maintained during a temperature decline down to 12 °C (after which TIN removal reduced to an average of 58% from 12 down to 8 °C). Our work demonstrates the impact of small changes in C : N on performance, population structure, and aggregate type (biofilm vs. floc) in mainstream deammonification bioprocesses and provides a simple approach to control C : N in practice.

中文翻译：

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优化碳氮比，实现主流脱氨作用，以及硝化作用从生物膜转移到悬浮液的过程

将脱氨工艺应用于主流废水有望实现能源高效的脱氮，但受到亚硝酸盐氧化细菌的有害活性和在中等温度（<20°C）下较低的厌氧氨氧化活性的限制。在本研究中，主流化的固定膜活性污泥（IFAS）脱氨工艺中的N去除通过将A级和左右一级废水的10％转移，使总无机氮（TIN）去除率提高了27％至73％。直接将其加入脱氨反应器中，从而将进水的C：N比从2.3 g sCOD / g NH ₄ ⁺增加到3.1 g-N。这种变化与硝化活性从生物膜到悬浮液的急剧变化相吻合，并且碳的增加使得在实际的固体保留时间为7.3±2.1天时，悬浮物的浓度更高。厌氧氨氧化生物量和活性在整个研究（> 3年）中均得到保留，并且不受进水碳增加的负面影响。氮同位素测试表明，反硝化器和厌氧氨氮之间的交叉进料在氮的去除中起着重要作用，并且最终约有53％的氮去除最终通过厌氧氨氮代谢进行。在大多数研究中，将反应器温度控制在20°C附近，并且在温度下降至12°C的过程中，TIN的去除率保持在72％（此后，TIN的去除率从12°C降至8°C降至平均58％ ）。与絮凝剂相比）在主流脱氨生物工艺中提供了实用的控制C：N的简单方法。