Abstract:

To investigate the wastewater purification efficiency and microbial community structure characteristics of constructed wetlands (CWs) beside Qilu Lake in Yunnan Plateau, the surface-flow CW located at the Zhonghe river estuary was taken as a representative for evaluating its removal efficiency for COD, N and P over a round year. The characteristics and differences of microbial community structure in the sediment along the wetland were analyzed by high-throughput sequencing technology. The results showed that the seasonal average removal efficiencies for NH₄⁺-N, NO₃^--N and TN of the CW at Zhonghe river estuary were 16.4%-73.7%, -5.16%-81.1% and 22.3%-64.7%, respectively, with better nitrogen removal achieved in autumn but poorer in spring. The average removal rates for TP and COD were 31.8% and 21.7%, respectively, with the efficiency being poor in some months and requiring improvement. Among functional purification units in the CW, the first surface-flow CW system exhibited the best removal efficacy for NH₄⁺-N, COD and TP, while the plant-strengthened sedimentation pond and facultative pond achieved the best removal efficiency for NO₃^--N and TN. Proteobacteria, Chloroflexi, Bacteroidetes, Acidobacteria, Firmicutes and Planctomycetes were the dominant phyla in the wetland sediment. At the genus level, Thiobacillus, Bacteroidetes_vadinHA17 and Candidatus_Competibacter, among others, showed high relative abundance. Microbial community richness and diversity were higher in the first surface-flow CW unit and facultative pond, and microbial community structures in the front and posterior sections of the CW were notably different, partly because of the accumulated pollutants and their levels. Various microorganisms played an important role in the wastewater purification in the CW at Zhonghe river estuary. This study can provide scientific reference for the construction, operation and management of CWs beside the plateau lakes for wastewater purification.

Key words: Qilu Lake, estuary constructed wetland, purification efficiency, purification units, microbial communities

摘要：

为探究云南高原湖泊杞麓湖湖滨人工湿地的污水净化效果及其微生物群落特征,以中河河口表面流湿地为研究对象,进行了为期1年的监测分析,考察该湿地对COD、N、P等污染物的去除效果,并通过高通量测序方法分析了湿地沿程底泥中微生物群落的结构特征与差异。结果表明,中河河口湿地对NH₄⁺-N、NO₃^--N和TN的季节平均去除率分别为16.4%-73.7%、5.16%-81.1%和22.3%-64.7%,其中秋季脱氮效果较好,而春季较差。TP和COD的平均去除率为31.8%和21.7%,部分月份去除效果较差,有待进一步强化。该湿地的各功能单元中,一级表流湿地对NH₄⁺-N、COD和TP的去除效果较佳,而植物强化沉淀塘和兼性塘对NO₃^--N、TN的去除效果较佳。湿地底泥微生物门水平上以变形菌门（Proteobacteria）、绿弯菌门（Chloroflexi）、拟杆菌门（Bacteroidetes）、酸杆菌门（Acidobacteria）和厚壁菌门（Firmicutes）为优势,属水平上相对丰度较高的是硫杆菌属（Thiobacillus）、Bacteroidetes_vadinHA17属和聚糖菌属（Candidatus_Competibacter）等。一级表流湿地和兼性塘的微生物丰富度和多样性较高,湿地沿程前后段的微生物群落结构差异明显,污染物及其水平是造成该差异的重要原因之一。各类微生物在该湿地污水净化中起着重要作用。该研究可为高原湖泊湖滨污水净化湿地的建设、运行和管理提供一定的科学参考。

关键词: 杞麓湖, 河口人工湿地, 净化效果, 净化单元, 微生物群落