低剂量长波紫外胁迫下活性污泥硝化活性及氧化应激响应

选取具备良好硝化能力的活性污泥为试验对象，考察其在不同强度（0，0.15，0.39，0.62和1.16μE/（L·s））及不同时间（0，1，2，3和4h）的长波紫外（UVA）辐照下，氨氧化菌（AOB）及亚硝酸盐氧化菌（NOB）活性的响应情况.结果显示：UVA辐照强度的增加对NOB活性产生显著性影响（P<0.01），而对AOB活性的影响则微乎其微（P>0.05），且随UVA辐照时间的延长，AOB与NOB之间活性差异越大.动力学拟合结果表明UVA辐照下NOB的衰亡速率（b=0.6938h^-1）远大于AOB （b=0.1423h^-1），NOB对于UVA辐照的耐受性低于AOB.UVA辐照下AOB与NOB活性差异可能与UVA诱导的氧化应激效应有关，即UVA辐照能够诱导微生物胞内活性氧（ROS）水平的激增，对细胞膜形成氧化性损伤，破坏细胞膜结构完整性，加速微生物走向衰亡.

Effect of low-dose ultraviolet-A (UVA) irradiation on nitrification activity of activated sludge and oxidative stress response

The effect of illumination intensity (0, 0.15, 0.39, 0.62 and 1.16μE/(L·s)) and duration (0, 1, 2, 3 and 4h) of UVA on the activities of ammonia oxidizing bacteria (AOB) and nitrite oxidizing bacteria (NOB) were investigated in well-performed nitrifying activated sludge. The results showed UVA irradiation significantly reduced activity of NOB (P < 0.01), while effect of UVA on AOB was insignificant (P > 0.05). AOB activity and NOB activity showed more significant difference as UVA irradiation prolonged. Dynamics modelling indicated that the decay rate of NOB (b=0.6938h^-1) was much higher than that of AOB (b=0.1423h^-1) under UVA, which implied that NOB was rather intolerant to UVA compared with AOB. The difference between AOB and NOB activities under UVA irradiation may associated with the oxidative stress effect induced by UVA, which would dramatically increase the level of intracellular reactive oxygen species (ROS), and thus damage the cell membrane, destroy the structural integrity of cell, and cause the cell decay.