Islam Chowdhury Mohammad Monirul, Nakhla George
Civil and Environmental Engineering, University of Western Ontario, London, Canada.
Chemical and Biochemical Engineering, University of Western Ontario, London, Canada.
Environ Technol. 2021 Jul 20:1-12. doi: 10.1080/09593330.2021.1951846.
Enrichment of anammox bacteria has long been considered to be time-consuming because of the slow growth rate. This study evaluated the impact of sludge retention time (SRT) on the enrichment of anammox bacteria with a focus on nitrogen removal and specific anammox activity (SAA) in sequencing batch reactors (SBR). A total of eight different SRTs in the range of 30-1280 days at nitrogen loading rates (NLR) range from 12.1 to 122.1 mg/L-d were used to evaluate the anammox activity. SAA was negligible during the first 105 days due to denitrification and continued to increase thereafter to peak at 0.22 g N/g VSS-d on day 530 as the solids and hydraulic retention times (SRT and HRT) decreased from 120 to 80 days and 10 to 2 days, respectively. The stability of SAA (0.21 ± 0.02 g N/g VSS-d) from day 503 to day 670 indicates that anammox bacteria should be enriched at SRTs ranging from 30 to 80 days and NLR of 122.1 mg N/L-d. Moreover, the SBR achieved a maximum nitrogen removal efficiency of 86.6% at an SRT of 30 days and an NLR of 122 mg/L-d. Microbial analysis indicated that the two most abundant microorganisms accounting for 48% of the bacterial population are Anammoxoglobus followed by the heterotrophic denitrifier Rhizobiales. The maximum specific growth rate (was estimated as 0.062 d, consistent with typical of 0.057 d. The average first-order decay rate was estimated as 0.008 d, and the half-saturation constants (ks) averaged 16.2 mg NH4-N/L.
由于厌氧氨氧化细菌生长速率缓慢，长期以来人们一直认为富集该细菌耗时较长。本研究评估了污泥停留时间（SRT）对厌氧氨氧化细菌富集的影响，重点关注序批式反应器（SBR）中的氮去除和比厌氧氨氧化活性（SAA）。在氮负荷率（NLR）为12.1至122.1 mg/L-d的范围内，共使用了8种不同的SRT（30 - 1280天）来评估厌氧氨氧化活性。由于反硝化作用，在最初的105天内SAA可忽略不计，此后随着固体停留时间（SRT）和水力停留时间（HRT）分别从120天降至80天以及从10天降至2天，SAA持续增加，并在第530天达到峰值0.22 g N/g VSS-d。从第503天到第670天SAA的稳定性（0.21±0.02 g N/g VSS-d）表明，厌氧氨氧化细菌应在SRT为30至80天且NLR为122.1 mg N/L-d的条件下进行富集。此外，该SBR在SRT为30天且NLR为122 mg/L-d时实现了86.6%的最大氮去除效率。微生物分析表明，占细菌总数48%的两种最丰富的微生物是厌氧氨氧化球菌，其次是异养反硝化菌根瘤菌目。最大比生长速率估计为0.062 d⁻¹，与典型值0.057 d⁻¹一致。平均一级衰减速率估计为0.008 d⁻¹，半饱和常数（ks）平均为16.2 mg NH₄-N/L。
