State Key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, 18 Shuangqing Road, Haidian District, Beijing, China.
Water Res. 2010 May;44(9):2823-30. doi: 10.1016/j.watres.2010.02.021. Epub 2010 Feb 21.
Three submerged membrane bioreactors (MBRs) were operated continuously for 230 days by feeding with synthetic inorganic wastewater (NH(4)(+)-N, 100 mg L(-1)) under different solids retention times (SRTs. M(30d), 30 days; M(90d), 90 days; M(infinite), no sludge purge) to examine the influence of SRT on nitrification performance and microbial characteristics. All the reactors could oxidize NH(4)(+)-N to NO(3)(-)-N effectively without accumulation of NO(2)(-)-N. M(30d) with the shortest SRT showed significantly higher specific ammonium oxidizing rate (SAOR, 0.22 kg NH(4)(+)-N kg(-1) MLSS day(-1)) and specific nitrate forming rate (SNFR, 0.13 kg NO(3)(-)-N kg(-1) MLSS day(-1)) than the other two MBRs (0.12-0.14 kg NO(3)(-)-N kg(-1) MLSS day(-1) and 0.042-0.068kg NO(3)(-)-N kg(-1) MLSS day(-1), respectively). Short SRT led to low extracellular polymeric substances (EPS) concentration and long operating cycle. The nitrite oxidizing bacteria (NOB) ratios by both the fluorescence in situ hybridization (FISH) (3.6% for M(30d) and 2.1-2.2% for M(90d) and M(infinite)) and MPN (1.4 x 10(7)cells g(-1) MLSS for M(30d) and 6.2 x 10(5) and 2.7 x 10(4)cells g(-1) MLSS for M(90d) and M(infinite)) analyses showed that M(30d) favored the accumulation of NOB, which was in accordance with the SNFR result. However, the ammonia oxidizing bacteria (AOB) ratios (3.5%, 3.2% and 4.9% for M(30d), M(90d) and M(infinite)) were not in accordance with the SAOR result. PCR-DGGE, clone library and FISH results showed that the fast-growing Nitrosomonas and Nitrobacter sp. were the dominant AOB and NOB, respectively for M(30d), while considerable slow-growing Nitrosospira and Nitrospira sp. existed in M(infinite), which might be an important reason why M(infinite) had a low SAOR and SNFR.
三个浸没式膜生物反应器（MBR）连续运行 230 天，用合成无机废水（NH 4 (+)-N，100mg/L）进料，不同的固体停留时间（SRT。M（30d），30 天；M（90d），90 天；M（无限），无污泥冲洗）考察 SRT 对硝化性能和微生物特性的影响。所有反应器都能有效地将 NH 4 (+)-N氧化为 NO 3 (-)-N，而不会积累 NO 2 (-)-N。具有最短 SRT 的 M（30d）表现出明显更高的比氨氧化速率（SAOR，0.22kgNH 4 (+)-Nkg（-1）MLSS 天（-1））和比硝酸盐形成速率（SNFR，0.13kgNO 3 (-)-Nkg（-1）MLSS 天（-1））比其他两个 MBR（0.12-0.14kgNO 3 (-)-Nkg（-1）MLSS 天（-1）和 0.042-0.068kgNO 3 (-)-Nkg（-1）MLSS 天（-1），分别）。短 SRT 导致胞外聚合物（EPS）浓度低和操作周期长。通过荧光原位杂交（FISH）（M（30d）为 3.6%，M（90d）和 M（无限）为 2.1-2.2%）和最大可能数（MPN）（M（30d）为 1.4×10（7）细胞 g（-1）MLSS，M（90d）和 M（无限）为 6.2×10（5）和 2.7×10（4）细胞 g（-1）MLSS）分析表明，M（30d）有利于 NOB 的积累，这与 SNFR 的结果一致。然而，氨氧化细菌（AOB）的比例（M（30d）、M（90d）和 M（无限）分别为 3.5%、3.2%和 4.9%）与 SAOR 结果不一致。PCR-DGGE、克隆文库和 FISH 结果表明，快速生长的硝化菌和硝化杆菌分别是 M（30d）中优势 AOB 和 NOB，而在 M（无限）中存在相当数量的慢速生长的硝化螺旋菌和硝化螺旋菌，这可能是 M（无限）具有低 SAOR 和 SNFR 的一个重要原因。
