School of Civil Engineering, Key Laboratory of Water Supply &, Sewage Engineering Ministry of Housing and Urban-Rural Development, Chang'an University, Xi'an, 710054, China.
School of Water and Environment, Chang'an University, Xi'an, 710055, China.
Environ Sci Pollut Res Int. 2022 Mar;29(13):18793-18804. doi: 10.1007/s11356-021-17058-5. Epub 2021 Oct 26.
Denitrification and dissimilatory nitrate reduction to ammonium (DNRA) are two competing pathways in nitrate-reducing process. In this study, a series of C/S ratios from 8:1 to 2:4 were investigated in a sequencing biofilm batch reactor (SBBR) to determine the role of reducers (sulfide and acetate) on their competition. The results showed that the proportion of DNRA increased in high electron system, either in organic-rich system or in sulfide-rich system. The highest DNRA ratio increased to 16.4% at the C/S ratio of 2:3. Excess electron donors, particularly sulfide, were favorable for DNRA in a limited nitrate environment. Moreover, a higher reductive environment could facilitate DNRA, especially, when ORP was lower than - 400 mV in this system. 16S rRNA gene sequencing analysis demonstrated that Geobacter might be the important participant involved in DNRA process in organic-rich system, while Desulfomicrobium might be the dominant DNRA bacteria in sulfide-rich system. DNRA cultivation could enrich nitrogen conversion pathways in conventional denitrification systems and deepen the insight into nitrogen removal at low C/N.
反硝化和异化硝酸盐还原为铵（DNRA）是硝酸盐还原过程中的两种竞争途径。在这项研究中，使用序批式生物膜反应器（SBBR）研究了从 8:1 到 2:4 的一系列 C/S 比，以确定还原剂（硫化物和乙酸盐）对其竞争的作用。结果表明，在富电子体系中，无论是在富有机体系还是在富硫化物体系中，DNRA 的比例均增加。在 C/S 比为 2:3 时，DNRA 比例最高增加到 16.4%。过量的电子供体，特别是硫化物，在有限的硝酸盐环境中有利于 DNRA。此外，在该体系中，当氧化还原电位（ORP）低于-400 mV 时，还原性环境更有利于 DNRA。16S rRNA 基因测序分析表明，在富有机体系中，产电菌可能是参与 DNRA 过程的重要参与者，而脱硫微生物可能是富硫化物体系中占主导地位的 DNRA 细菌。DNRA 培养可以丰富传统反硝化系统中的氮转化途径，并深入了解低 C/N 下的脱氮。
