Biochar is an inexpensive redox-active carbon material that has been demonstrated to enhance microbial nitrogen-transforming processes. However, how redox-active biochar affects anammox remains unclear. Here, the effects of three functionally distinct biochars produced from corn stover biomass at varied pyrolysis temperatures (CS300, CS500, CS800) were evaluated as additives on the anammox performance in three reactors (R300, R550, R800) over the long term, during which nitrogen loading rate was either increased drastically (pulse strategy) or gradually (gradual strategy). Nitrogen removal was achieved at 86.5% (R300), 77.1% (Control), 59.3% (R550) and 57.7% (R800) under pulse strategy, and at 95.4% (R300), 92.3% (R550), 86.2% (Control) and 82.0% (R800) under gradual strategy, respectively. Compared with Control, addition of CS300 increased abundance of Candidatus Kuenenia with superior anammox activity. CS300 enriched with reduced functional groups (phenolic/hydroquinone) could donate electrons to support bioenergetics of anammox metabolism, whereas electron-accepting CS800 functioned inversely. Overall, this study highlights the importance of surface functional groups and redox property of biochar such that determines whether its addition impose stimulatory or suppressive effect on anammox process.

生物炭是一种廉价的氧化还原活性碳材料，已被证明可以增强微生物氮转化过程。然而，还不清楚氧化还原活性生物炭如何影响厌氧氨氧化。在这里，从玉米秸秆生物质在不同的热解温度下产生的三种功能独特的生物炭（CS300，CS500，CS800）的影响作为添加剂对三个反应器（R300，R550，R800）中厌氧氨氧化性能的长期影响进行了评估，在此期间氮负荷率急剧增加（脉冲策略）或逐渐增加（渐进策略）。在脉冲策略下，脱氮率分别为86.5％（R300），77.1％（对照），59.3％（R550）和57.7％（R800），以及95.4％（R300），92.3％（R550），86.2％（对照） ）和渐进策略下的82.0％（R800）。与对照相比，Candidatus Kuenenia具有出色的厌氧氨氧化活性。富含减少的官能团（酚/对苯二酚）的CS300可以捐赠电子来支持厌氧氨氧化代谢的生物能，而接受电子的CS800则起相反的作用。总的来说，这项研究强调了生物炭的表面官能团和氧化还原特性的重要性，从而确定了其添加对厌氧氨氧化工艺是否具有刺激或抑制作用。