The membrane units, pretreatment and post-treatment are examined to explore the engineering process of membrane applications herein. The widely used membrane separation technologies in industrial wastewater treatment include RO, ultrafiltration (UF), and Membrane bioreactor (MBR). RO membrane manufacturing is standardized and the operation is very stable. RO is the finest separation membrane process with pore sizes ranging from 0.0001 m to 0.001 m. The disadvantage of RO is that it requires substantial pretreatment. If the permeate only pass one RO membrane, the method is refereed as single RO. It the permeate passes two RO membranes, the method is defined as double RO. UF is a variety of membrane filtration to perform separation via a semipermeable membrane by forces like pressure or concentration. Pore size of UF is between 0.01 m and 0.1 m. Solutes of high molecular weight are retained while water and low molecular weight solutes pass through the membrane. UF is cable to filter suspended solids and microbe so that RO membrane is protected from these pollutants. The facility with UF pretreatment will use much less area and the quality of generated water is very stable. MBR is the combination of a membrane process with a suspended growth bioreactor. This process has high biochemical treatment efficiency with good separation of solids and liquids. MBR facility also takes small amount of area to build and could be controlled automatically. MBR is widely used for municipal and industrial wastewater treatment