Effect of Different Temperature and Anaerobic/Aerobic Conditions on the Decay Characteristics of PAOs

In order to analyze the effect of different temperatures on PAOs decay, a lab scale EBPR culture with PAOs over 90%±2% of the entire bacterial was used under different conditions (10℃ anaerobic, 10℃ aerobic, 20℃ anaerobic, 20℃ aerobic). The results show that the decay rate increases with the increase of temperature; the average rate during 1~9 days is (respectively: 10℃ anaerobic, 10℃ aerobic, 20℃ anaerobic, 20℃ aerobic) 0.053/d, 0.50/d, 0.072/d, and 0.145/d; the cell death rate is 0.019/d, 0.017/d, 0.019/d, and 0.03/d, which accounts for 35.8%, 34%, 26.4%, and 20.7% of the decay rate, respectively. The concentration of PHA and glycogen decreases during the decay period. And Glycogen degrades quickly in anaerobic conditions than in aerobic conditions under the same temperature. The glycogen degrade rate is higher with the increase of temperature under the same anaerobic and aerobic conditions.     

Effect of Nitrite on Anaerobic Metabolism of Phosphate Accumulating Organisms

Two enhanced biological phosphorus removal (EBPR) sludges were used to investigate the effect of nitrite on anaerobic metabolism of phosphate accumulating organisms (PAOs). It is found that tolerance of PAOs to nitrite in two sludges were different. In the sludge with enriched PAOs cultures treating synthetic wastewater, when nitrite is above 10 mg/L, it inhibits VFA-uptake of PAOs, leading to decrease of PHA synthesis and increase of phosphate release. In the sludge with nitrogen and phosphorus removal by shortcut nitrification treating real domestic wastewater, anaerobic metabolism of PAOs is not inhibited even when nitrite is 30 mg/L; however, the presence of nitrite in anaerobic period causes denitrifying bacteria compete for limited carbon sources with PAOs, resulting in decrease of PHA synthesis and phosphate release. For the enriched PAOs cultures, the ratio of P/VFA obviously increases when nitrite is added in the reactor, indicating increased energy requirement for PAOs to take up VFA. The quantification results for PAOs in two sludges using fluorescence in-situ hybridization (FISH) show that the PAOs level is 55% in the enriched PAOs cultures, and 7.6% in the sludge with nitrogen and phosphorus removal by shortcut nitrification.     

约氏不动杆菌（Acinetobacter johnsonii）的分离及其聚磷特性的研究

采用定性、定量相结合的方法,从城市污水中筛选到一株高效聚磷菌（CH-1）,经生理生化特征及16 rDNA序列分析,鉴定该菌株为不动杆菌属的约氏不动杆菌（Acinetobacter johnsonii）。进行了该菌株的生长曲线、含磷培养液的pH、磷酸盐浓度变化及去磷效果等测定。结果表明：该菌在培养6—8h时繁殖量达到最大（0．54mg／L）,培养液pH值达到最高（8．88）,而磷酸盐浓度降至最低（1．08mg／L）。好氧条件下,含磷培养液培养72h后,培养液中磷浓度由10mg／L降至3．476mg／L,去磷率高达65．24％。CH-1菌处理模拟废水的除磷率高达68．88％,具有较强的聚磷能力。