Advanced Water Management Centre, The University of Queensland, St Lucia, Queensland 4072, Australia.
Advanced Water Management Centre, The University of Queensland, St Lucia, Queensland 4072, Australia.
Water Res. 2018 Apr 1;132:71-78. doi: 10.1016/j.watres.2017.12.064. Epub 2017 Dec 27.
The discovery of denitrifying anaerobic methane oxidation (DAMO) has not only improved our understanding of global methane and nitrogen cycles, but also provided new technology options for removal of nitrate from nitrate-contaminated water. Previous studies have demonstrated DAMO organisms could remove nitrate and nitrite from wastewater under strictly anaerobically conditions. In the study, we investigate the feasibility of nitrate removal from groundwater, which contains dissolved oxygen in addition to nitrate. A membrane biofilm reactor (MBfR), inoculated with DAMO co-culture, was capable of treating synthetic groundwater containing highly contaminated nitrate (50 mg N/L) and oxygen (7-9 mg O/L), with a maximum volumetric nitrate removal rate of 45 mg N/L-d. Accumulations of acetate and propionate were observed in some transient periods, indicating the possible involvement of acetate and propionate as intermediates in methane oxidation. The 16 S rRNA gene amplicon sequencing revealed that Candidatus Methylomirabilis, a known bacterial DAMO organism able to couple nitrite reduction with anaerobic oxidation of methane (AOM), was the dominant population. No archaeal DAMO organisms that are capable of coupling nitrate to AOM were observed, however, considerable amount of denitrifiers were developed in this system. Based on known metabolisms of these microorganisms and a series of batch studies, it was assumed that methane was oxidized into volatile fatty acids (VFAs) under oxygen-limiting conditions, then the generated VFAs served as carbon sources for these heterotrophic denitrifiers to remove nitrate. This study offers a potential technology for nitrate removal from groundwater by DAMO process in MBfR.
反硝化厌氧甲烷氧化（DAMO）的发现不仅提高了我们对全球甲烷和氮循环的认识，而且为去除硝酸盐污染水提供了新的技术选择。先前的研究已经证明 DAMO 微生物可以在严格的厌氧条件下从废水中去除硝酸盐和亚硝酸盐。在这项研究中，我们研究了从含有溶解氧的地下水去除硝酸盐的可行性。采用 DAMO 共培养物接种的膜生物膜反应器（MBfR）能够处理含有高浓度硝酸盐（50mgN/L）和氧气（7-9mgO/L）的合成地下水，最大容积硝酸盐去除率为 45mgN/L-d。在一些短暂的时期观察到乙酸盐和丙酸盐的积累，表明甲烷氧化过程中可能涉及乙酸盐和丙酸盐作为中间产物。16S rRNA 基因扩增子测序结果表明，Candidatus Methylomirabilis 是一种已知的能够将亚硝酸盐还原与甲烷厌氧氧化（AOM）偶联的细菌 DAMO 微生物，是优势种群。然而，没有观察到能够将硝酸盐与 AOM 偶联的古菌 DAMO 微生物，但在该系统中大量产生了反硝化微生物。根据这些微生物的已知代谢途径和一系列批处理研究，假设在氧气限制条件下，甲烷被氧化成挥发性脂肪酸（VFAs），然后生成的 VFAs 作为这些异养反硝化微生物去除硝酸盐的碳源。这项研究为 DAMO 过程在 MBfR 中从地下水去除硝酸盐提供了一种潜在的技术。
