LI Hong,ZHANG Li-qiu,ZHANG Shao-qing,et al.Effects of Cd2+ Stress on Partial Denitrification and Change of Microbial Community[J].China Water & Wastewater,2021,37(5):10-16.
Cd2+胁迫对短程反硝化的影响与微生物群落变化
- Title:
- Effects of Cd2+ Stress on Partial Denitrification and Change of Microbial Community
- 关键词:
- 短程反硝化; 乙酸钠; Cd2+胁迫; 胞外聚合物(EPS); 微生物群落
- Keywords:
- partial denitrification; sodium acetate; cadmium stress; extracellular polymeric substances; microbial community
- 摘要:
- 接种城市污水厂二沉池污泥，以乙酸钠为碳源，通过合理控制NO3--N浓度和COD/NO3--N启动短程反硝化（PD），并考察了长期投加不同Cd2+浓度的PD性能、胞外聚合物EPS和微生物群落变化。经过84 d的驯化成功启动PD，出水NO2--N浓度和亚硝酸盐积累率（NAR）均处于较高水平，其最高值分别为33.94 mg/L和81.24%，系统平均NAR为71.99%。Cd2+胁迫试验表明，与空白对照组S1相比，S2(2.5 mg/L)、S3(5 mg/L)和S4(10 mg/L)均呈现不同程度的短程反硝化性能恶化趋势，到第36天S2、S3和S4平均NAR分别下降了12.48%、14.59%和19.00%，但在高浓度Cd2+（5 、10 mg/L）条件下，系统仍具有较高的NAR。重金属对微生物活性的毒性抑制导致S2的EPS含量高于S3和S4的EPS含量，EPS含量显著增加说明微生物通过分泌大量EPS来吸附Cd2+。微生物高通量测序表明，变形菌门、拟杆菌门和绿弯菌门居PD系统主导地位，反应器NO2--N积累菌属Thauera的丰度表现为S2（2.13%）＞S3（0.28%）＞S1（0.2%）＞S4（0.1%），表明10 mg/L的Cd2+不利于Thauera菌属生长，Cd2+浓度低于5 mg/L时Thauera菌属有生长的趋势。
- Abstract:
- Using the sludge from the secondary settling tank of the municipal wastewater treatment plant as the inoculation sludge and sodium acetate as the carbon source,partial denitrification (PD) was started through reasonable control of NO3--N concentration and COD/NO3--N,and the performance of partial denitrification with different concentrations of Cd2+,the extracellular polymeric substances（EPS） and microbial community changes were investigated.The results showed that after 84 days of domestication, partial denitrification could be successfully started,and the NO2--N concentration of the effluent and nitrite accumulation rate (NAR) were at a relatively high level, with the highest values of 33.94 mg/L and 81.24%,the average NAR was 71.99%.The Cd2+ stress test showed that compared with the blank control group S1, S2 (2.5 mg/L),S3 (5 mg/L) and S4(10 mg/L) all showed different degrees of deterioration of partial denitrification performance. By the 36th day,the average NAR of S2,S3 and S4 decreased by 12.48%,14.59% and 19.00% respectively. Under the condition of high concentration Cd2+(5 mg/L and 10 mg/L), the system still had a higher NAR. The toxicity inhibition of heavy metals on microbial activity resulted in the EPS content of S2 being higher than that of S3 and S4. The significant increase in EPS content indicated that the microorganisms secreted a large amount of EPS to adsorb Cd2+. High-throughput sequencing showed that Proteobacteria, Bacteroidetes and Chloroflexi were dominant in partial denitrification system, and the abundance of Thauera was S2(2.13%)＞S3(0.28%)＞S1(0.2%)＞S4(0.1%), indicating that 10 mg/L of Cd2+ was not conducive to the growth of Thaurea, and when the concentration of Cd2+ was lower than 5 mg/L,Thaurea tended to grow.
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