Abstract In this study, the microbial community for denitrification in the down-flow hanging sponge (DHS) reactor was estimated by batch experiment and microbial community analysis. Sludge retained from the DHS reactor, which conducts single-stage nitrification-denitrification, was collected into a series of vials as seed sludge for the batch experiment. Nitrate, nitrite, and nitrous oxide were added as nitrogen sources for each vial series. Sodium acetate solution was added to each vial series as a carbon source. At the beginning of the batch experiment, nitrous oxide was accumulated from only the nitrite-fed series (NO2 series). Approximately 50% of reduced nitrate was accumulated as nitrite in the nitrate-fed series (NO3 series). After two weeks of cultivation, nitrous oxide began to accumulate in the NO3 series without nitrite accumulation. Nitrous oxide accumulation was not confirmed in the NO3 series after 15 days of cultivation. During the batch experiment, the predominant denitrifying bacteria changed from Alicycliphilus to Thauera in the NO3 series. By contrast, the nitrous oxide producer Propionibacterium and the nitrous oxide reducer Staphylococcus increased in the NO2 series only. Thus, nitrite accumulation was considered to be a key factor for nitrous oxide emission in the DHS reactor. In addition, it was suggested that both nitrifying and denitrifying bacteria contributed to prevention of nitrite accumulation in the DHS reactor.

中文翻译：

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下流式悬挂海绵（DHS）反应器反硝化微生物群落估算

摘要 在本研究中，通过批量实验和微生物群落分析估计了下流式悬挂海绵（DHS）反应器中用于反硝化的微生物群落。从进行单级硝化-反硝化的 DHS 反应器中保留的污泥被收集到一系列小瓶中作为批量实验的种子污泥。添加硝酸盐、亚硝酸盐和一氧化二氮作为每个小瓶系列的氮源。将乙酸钠溶液作为碳源添加到每个小瓶系列中。在批量实验开始时，一氧化二氮仅从亚硝酸盐系列（NO2 系列）中积累。在硝酸盐喂养系列（NO3 系列）中，大约 50% 的还原硝酸盐以亚硝酸盐的形式积累。培养两周后，NO3系列开始积累一氧化二氮，没有亚硝酸盐积累。培养 15 天后，NO3 系列中未确认氧化亚氮积累。在批量实验过程中，NO3系列中的优势反硝化细菌从Alicycliphilus变为Thauera。相比之下，一氧化二氮生产者丙酸杆菌和一氧化二氮还原剂葡萄球菌仅在 NO2 系列中增加。因此，亚硝酸盐的积累被认为是 DHS 反应器中一氧化二氮排放的关键因素。此外，有人建议硝化和反硝化细菌都有助于防止 DHS 反应器中亚硝酸盐的积累。一氧化二氮生产者丙酸杆菌和一氧化二氮还原剂葡萄球菌仅在 NO2 系列中增加。因此，亚硝酸盐的积累被认为是 DHS 反应器中一氧化二氮排放的关键因素。此外，有人建议硝化和反硝化细菌都有助于防止 DHS 反应器中亚硝酸盐的积累。一氧化二氮生产者丙酸杆菌和一氧化二氮还原剂葡萄球菌仅在 NO2 系列中增加。因此，亚硝酸盐的积累被认为是 DHS 反应器中一氧化二氮排放的关键因素。此外，有人建议硝化和反硝化细菌都有助于防止 DHS 反应器中亚硝酸盐的积累。