连续流模式快速培养部分硝化/厌氧氨氧化(PN/A)颗粒污泥是生活污水生物脱氮的关键技术之一。与PN/A颗粒污泥相比,PN颗粒污泥显示出较短的潜伏期和分批培养的适用性。它也是富集厌氧氨氧化(AMX)细菌的良好载体。在这项研究中,在3个连续搅拌釜反应器(CSTR)(R1-R3)中,以3∶1、1∶1和1∶3的质量比接种PN/A和PN颗粒污泥,建立了连续流自养脱氮工艺。通过实施高氨氮负荷和短水力停留时间,在三个CSTR中成功启动了连续自养脱氮过程。结果表明,与R1和R2相比,R3的启动时间更长,但稳态脱氮性能相似。R3的总脱氮负荷大于2.6kg·(m3·d)-1。有趣的是,接种的PN颗粒污泥是PN/A颗粒污泥培养的前体。该方法通过向CSTR中引入丰富的氨氧化细菌(AOB)和亚硝酸盐氮底物,促进厌氧氨氧化细菌(AMX)的富集。根据高通量测序的结果,R1-R3中成熟颗粒的微生物丰度和多样性明显高于接种污泥。AOB(亚硝基单胞菌属),AMX(Kuenenia念珠菌和Brocadia念珠菌),和共生异养生物,比如氯氟菌,拟杆菌,和绿虫,驱动了自养脱氮过程,保持了颗粒结构的稳定。总之,为连续流自养脱氮工程应用提供了一种新型的混合接种颗粒污泥启动策略。
The rapid cultivation of partial nitritation/ANAMMOX (PN/A) granular sludge in a continuous-flow mode is one of the key technologies for efficient biological nitrogen removal in domestic wastewater treatment. Compared with that in PN/A granular sludge, PN granular sludge demonstrates a shorter incubation period and suitability for batch culture. It is also a good carrier for enriching ANAMMOX (AMX) bacteria. In this study, we established a continuous-flow autotrophic nitrogen removal process in three continuously stirred tank reactors (CSTR) (R1-R3) by hybrid-inoculating PN/A and PN granular sludge at the mass ratios of 3∶1, 1∶1, and 1∶3, respectively. By implementing high ammonium nitrogen loading and short hydraulic retention time, continuous autotrophic nitrogen removal processes were successfully started up in the three CSTRs. The results showed that compared with that of R1 and R2, R3 had a longer start-up time but a similar steady-state nitrogen removal performance. The total nitrogen removal load of R3 could be more than 2.6 kg·(m3·d)-1. Intriguingly, the inoculated PN granular sludge served as a precursor for PN/A granular sludge cultivation. This approach facilitated the enrichment of anaerobic ammonia-oxidizing bacteria (AMX) by introducing abundant ammonium-oxidizing bacteria (AOB) and nitrite nitrogen substrates into the CSTR. According to the results of high-throughput sequencing, the microbial abundance and diversity of the mature granules in R1-R3 were significantly higher than those of the inoculation sludge. AOB (genus Nitrosomonas), AMX (genera Candidatus Kuenenia and Candidatus Brocadia), and symbiotic heterotrophs, such as Chloroflexi, Bacteroidetes, and Chlorobi, drove the autotrophic nitrogen removal process and maintained the stability of the granular structure. In summary, a novel start-up strategy of hybrid-inoculating granular sludge was provided for a continuous-flow autotrophic nitrogen removal in engineering application.