This study compared denitrification performances and microbial communities in fluidized bed reactors (FBRs) carrying out autotrophic denitrification using elemental sulfur (S⁰) and pyrite (FeS₂) as electron donors. The reactors were operated for 220 days with nitrate loading rates varying between 23 and 200 mg N-NO${}_3^{-}$/L$\cdot$d and HRT between 48 and 4 h. The highest denitrification rates achieved were 142.2 and 184.4 mg N-NO${}_3^{-}$/L$\cdot$d in pyrite and sulfur FBRs, respectively. Pyrite-driven denitrification produced less SO${}_4^{2-}$ and no buffer addition was needed to regulate the pH. The sulfur FBR needed instead CaCO₃ to maintain the pH neutral and consequentially more sludge was produced (CaSO₄ precipitation). The active community of pyrite-based systems was investigated and Azospira sp., Ferruginibacter sp., Rhodococcus sp. and Pseudomonas sp. were the predominant genera, while Thiobacillus sp. and Sulfurovum sp. dominated the active community in the sulfur FBR. However, Thiobacillus sp. became more dominant when operating at elevated nitrogen loading rate. Patterns of diversity and microbial community assembly were assessed and revealed three distinct stages of microbial community succession which corresponded with the operation of a period of high influent nitrate concentration (135 mg N-NO${}_3^{-}$/L). It is proposed that a high degree of functional redundancy in the initial microbial communities may have helped both reactors to respond better to such high influent nitrate concentration.

^{本研究比较了使用元素硫 (S 0} ) 和黄铁矿 (FeS ₂ ) 作为电子供体进行自养反硝化的流化床反应器 (FBR) 的反硝化性能和微生物群落。反应器运行 220 天，硝酸盐负载率在 23 至 200 mg N-NO 之间变化${}_3^{-}$/L$\cdot$d 和 HRT 在 48 到 4 小时之间。达到的最高反硝化率分别为 142.2 和 184.4 mg N-NO${}_3^{-}$/L$\cdot$d 分别在黄铁矿和硫 FBR 中。黄铁矿驱动的反硝化产生较少的 SO${}_4^{2-}$并且不需要添加缓冲液来调节 pH 值。硫 FBR 需要 CaCO ₃来维持 pH 中性，因此产生更多的污泥（CaSO ₄沉淀）。研究了基于黄铁矿的系统的活跃群落，并研究了 Azospira sp .、 Ferruginibacter sp .。,红球菌属。和假单胞菌属。是主要属，而硫杆菌属。和Sulfurovum sp。在硫 FBR 中占主导地位。然而，硫杆菌属。当在较高的氮负荷率下运行时，它变得更加占主导地位。评估了多样性和微生物群落组装的模式，并揭示了微生物群落演替的三个不同阶段，这与高流入硝酸盐浓度（135 mg N-NO）的运行相对应${}_3^{-}$/L)。有人提出，初始微生物群落的高度功能冗余可能有助于两个反应器更好地响应如此高的进水硝酸盐浓度。