School of Civil Engineering and Geosciences, Newcastle University, Newcastle upon Tyne, UK.
J Appl Microbiol. 2013 Aug;115(2):621-30. doi: 10.1111/jam.12233. Epub 2013 May 16.
To provide deeper insights into nitrification process within aerobic bioreactors containing supplemental physical support media (hybrid bioreactors).
Three bench-scale hybrid bioreactors with different media size and one control bioreactor were operated to assess how biofilm integrity influences microbial community conditions and bioreactor performance. The systems were operated initially at a 5-day hydraulic retention time (HRT), and all reactors displayed efficient nitrification and chemical oxygen demand (COD) removal (>95%). However, when HRT was reduced to 2.5 days, COD removal rates remained high, but nitrification efficiencies declined in all reactors after 19 days. To explain reduced performance, nitrifying bacterial communities (ammonia-oxidizing bacteria, AOB; nitrite-oxidizing bacteria, NOB) were examined in the liquid phase and also on the beads using qPCR, FISH and DGGE. Overall, the presence of the beads in a reactor promoted bacterial abundances and diversity, but as bead size was increased, biofilms with active coupled AOB-NOB activity were less apparent, resulting in incomplete nitrification.
Hybrid bioreactors have potential to sustain effective nitrification at low HRTs, but support media size and configuration type must be optimized to ensure coupled AOB and NOB activity in nitrification.
This study shows that AOB and NOB coupling must be accomplished to minimize nitrification failure.
深入了解含有补充物理支撑介质（混合生物反应器）的好氧生物反应器中的硝化过程。
使用三种不同介质尺寸的实验室规模混合生物反应器和一个对照生物反应器进行操作，以评估生物膜完整性如何影响微生物群落条件和生物反应器性能。系统最初以 5 天水力停留时间（HRT）运行，所有反应器均显示出高效的硝化和化学需氧量（COD）去除率（>95%）。然而，当 HRT 降低至 2.5 天时，所有反应器在 19 天后 COD 去除率仍然很高，但硝化效率下降。为了解释性能下降的原因，使用 qPCR、FISH 和 DGGE 检查了液相和珠体上的硝化细菌群落（氨氧化细菌，AOB；亚硝酸盐氧化细菌，NOB）。总体而言，反应器中存在珠子会促进细菌丰度和多样性，但随着珠子尺寸的增加，具有活性偶联 AOB-NOB 活性的生物膜不太明显，导致硝化不完全。
混合生物反应器具有在低 HRT 下维持有效硝化的潜力，但必须优化支撑介质的尺寸和配置类型，以确保硝化过程中 AOB 和 NOB 的偶联。
本研究表明，必须实现 AOB 和 NOB 的偶联，以最小化硝化失败。
