School of Civil Engineering,Guangzhou University,Guangzhou 510006,China;
School of Environmental Science and Engineering,Sun Yat-sen University,Guangzhou 510275,China;
Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology,Sun Yat-sen University,Guangzhou 510275,China;
Membrane bioreactor; Activated sludge; Core community; Active population; Immigration impact;