[Characteristics and Regional Heterogeneity of Eukaryotic Microbial Community in Wastewater Treatment Plants]

Wastewater treatment plants (WWTPs) are important facilities to control water pollution and ensure the sustainable development of cities and humans. As an indispensable part of the activated sludge (AS) system, eukaryotic microbes play important roles in indicating the properties of AS, predicting the quality of the effluent, enhancing the purification effect, and ensuring a stable performance of the system in WWTPs. In this study, 61 AS samples from 14 full-scale WWTPs of Beijing, Shenzhen, and Wuxi were collected. Characteristics and regional heterogeneity of eukaryotic microbial community were elucidated via high-throughput sequencing (HTS) of the 18S rDNA and multi ecological and statistical methods. Results showed that eukaryotic microbial communities in different scales shared similar main members, which were mainly composed of fungi, ciliophora, and metazoa in division level with their total relative abundance up to 86.22%-89.40%. Diversity of eukaryotic microbial community in WWTPs of different cites varied. Richness and Shannon Wiener index of eukaryotic microbial communities in the AS system of Wuxi were the highest, while that of Beijing was the lowest. Diversity of eukaryotic microbes from HTS in this study was higher than that of conventional methods, but lower than the diversity of bacteria in AS systems. Regional heterogeneity of eukaryotic microbial community structure was uncovered by nonmetric multidimensional scaling based on Bray-Curtis distance and dissimilarity analysis. Results of partial mantel test and multiple regression matrix analysis showed that the eukaryotic microbial community was significantly correlated with the temperature of the aeration tank mixture and the total nitrogen concentration of the effluent of the AS system. These results help deepen the understanding of eukaryotic microbes in WWTPs.