Cl~-、SO_4~(2-)和PO_4~(3-)对异养反硝化污泥的胁迫效应

反硝化菌是反硝化作用的驱动者,探明Cl~-、SO_4~(2-)和PO_4~(3-)对异养反硝化污泥(HDS)的胁迫效应,有助于含盐废水生物脱氮技术的研发和优化.选用硝酸盐还原酶(周质酶)和碱性磷酸酯酶(胞内酶)作为指标,考察了不同Cl~-、SO_4~(2-)和PO_4~(3-)浓度对HDS酶活的影响;通过观测HDS中的活菌水平和细胞形态,考察了不同Cl~-、SO_4~(2-)和PO_4~(3-)浓度对HDS微生物细胞结构的影响.结果表明,Cl~-、SO_4~(2-)和PO_4~(3-)对HDS硝酸盐还原酶的半抑制浓度分别为0.15、0.12和0.05mol/L,对碱性磷酸酯酶的半抑制浓度为1.14、0.75和0.49mol/L;高浓度Cl~-、SO_4~(2-)和PO_4~(3-)导致HDS微生物细胞膜结构破损,通透性增加,细胞物质外泄.阴离子对HDS的胁迫可分为渗透胁迫和电荷胁迫,渗透胁迫造成HDS中功能酶失活,电荷胁迫造成HDS中细胞膜破损,细胞物质外泄.

Stress of Cl-, SO42- and PO43- on the heterotrophic denitrifying sludge

As the functional part of denitrification, denitrifier was obviously stressed by anions. To investigate the effects and the mechanism of anions on heterotrophic denitrifying sludge(HDS) are of great significance for the practical application of high-rate denitrification in saline nitrogen-rich wastewater treatments. Nitrate reductase and alkaline phosphatase were chosen as the indices to determine the effects of Cl^-, SO₄^2- and PO₄^3- on the enzyme activities in HDS, while the ratios of live/dead cells and cellular morphology were examined and observed to characterise the effects of Cl^-, SO₄^2- and PO₄^3- on the cell structures in HDS. Results showed that, the IC50values of Cl^-, SO₄^2- and PO₄^3- for nitrate reductase were 0.15, 0.12 and 0.05mol/L respectively, while the IC50values of Cl^-, SO₄^2- and PO₄^3- for alkaline phosphatase were 1.14, 0.75 and 0.49mol/L, respectively. Anions with high concentrations(1.71mol/L Cl^-, 0.85mol/L SO₄^2-, 0.57mol/L PO₄^3-) resulted in the damage of cell membranes, and caused the leakage of cell inclusion. In conclusion, the effects of anions on HDS were attributed to the osmotic stresses which affected the enzyme activities, and the ion stresses which caused the damage of cell membranes.