Wastewater treatment performance and microbial community structure in the constructed wetland under double-pressure of low temperature and Ag NPs exposure

低温和银纳米粒子双重胁迫下人工湿地的污水处理效果和微生物群落结构

To investigate the effects of silver nanoparticles(Ag NPs)and low temperature double-pressure on the wastewater treatment efficacy and the microbial community structure of constructed wetlands,a pilot-scale vertical flow constructed wetland was set up to treat synthetic wastewater under laboratory conditions.By measuring the effluent concentration of ammonia nitrogen(NH_(4)^(+)-N),total nitrogen(TN),total phosphorus(TP),chemical oxygen demand(COD),and the diversity,richness,and community structure of microorganisms of the upper and lower soil layers in the wetland,the nutrient removal effect of the constructed wetland and the changes in the microflora of the soil layer were studied.The results reveal that the correlation coefficients between the removal rates of TN and NH_(4)^(+)-N and the temperature are 0.463 and 0.692,respectively,indicating a significant positive correlation.From the warm to the cold season,both the diversity and richness of microorganisms in the lower soil layer of wetlands are inhibited under the double-pressure of Ag NPs and low temperature,and the abundances of the denitrogenation functional bacteria such as Candidatus nitrososphaera,Sulfuritalea,Anaeromyxobacter,Candidatus solibacter,Nitrospira,and Zoogloea are altered.Low temperature and Ag NPs exposure can thus affect the wastewater treatment performance of constructed wetlands,possibly because of the seasonal changes of the microflora.

为探究银纳米颗粒和低温双重胁迫对人工湿地污水处理效果和微生物群落结构的影响,在实验室条件下搭建了中试规模的垂直流人工湿地以处理合成废水.通过测定人工湿地出水中氨氮(NH_(4)^(+)-N)、总氮(TN)、总磷(TP)、化学需氧量(COD)浓度以及湿地上下土壤层内微生物的多样性、丰富度和群落结构,分析人工湿地对污水的处理效果和土壤基质内微生物的变化情况.结果表明,湿地TN、NH_(4)^(+)-N去除率与温度的相关系数分别为0.463和0.692,呈显著正相关性.从暖季到冷季,银纳米粒子与低温双重胁迫使湿地下层土壤微生物多样性及丰富度降低,并改变了氨氧化古菌属、硫针菌属、厌氧粘细菌、假丝酵母菌属、硝化螺旋菌属和菌胶团等脱氮功能细菌的丰度,从而影响了人工湿地的污水处理效果,究其原因可能是特定微生物物种随季节发生了变化.