Wastewater treatment by activated sludge is one of the most important biotechnological processes and has been used for more than 80 years. However, the information on correlations between the microbial community structure and function of activated sludge is less provided. Due to intricate interactions within the microbial community, it is important to detect the prominent population and describe microbial community structure in the wastewater treatment process. Conventional cultivation methods often result...