• Membrane is a unit for high-effective filtering by means of physical method, implicating that in a fluid phase or between two kinds of fluid phases there is a thin condensed phase which is to separate fluid into two interrupted sections. And it creates mass transferring action between these two sections. Such membrane includes micro filtration, ultra filtration, nano-filtration, reverse osmosis membrane.
• Filter membrane: The filter membrane is a unit for highly-effective filtering, referring that in a fluid phase or between two kinds of fluid phases there is a thin layer of condensed phase which is to separate fluid into two interrupted sections and is to create mass transferring action between these two sections.
• Hollow fiber membrane: products shape as fiber, hollow with a membrane for bracing function, also called membrane fibers.
• Asymmetrical membrane: A membrane in which its membrane structure is to change with hole depth.
• Micro filtration membrane: Micro filtration membrane refers to a membrane with sieving filtration function with pore diameter 0.1-10μm.
• Ultra-filtration-membrane: Ultra filtration-membrane refers to a membrane with sieving filtration function with pore diameter 0.002~0.1μm.
• Nano-filtration membrane: Nano-filtration membrane refers to semi-permeable membrane used to release polyvalence ion, and salt with single valence and organism with molecular weight larger than 200.
• Reverse osmosis membrane: The semi-permeable membrane is used for separation of solvent with solute in reverse osmosis process is called reverse osmosis membrane.
• Membrane module: Membrane module is an practical unit and composed of membrane, membrane support, fluid separation, shell and seal ring.
• Cross-flow filtration: A separation process in which pressure is to push solvent to flow through membrane vertically (vertical fluid) in parallel to membrane surface (tangential flow)..
• Full fluid filtration (dead end filtration): A operation mode by which all solvent is forced to pass through membrane.
• Raw water: In membrane application, the water without passing through membrane filtration treatment is called raw water.
• Permeate water: The water passes through filtration membrane.
• Concentrated water: Concentrated water refers to the part of raw water which cannot pass through membrane, it contains more concentrated particles, colloid, germs and thermo plasma than that of raw water. (Concentrated liquid in desalting or separation process.)

Note 1: The dissolved solids or particles or both in this part of concentrated water are higher than the water supply.

Note 2: For the cross-flow membrane process, is the part that fails to cross through the membrane in water.

• Flux: Water passes through membrane in unit time, generally expressed as water output of unit membrane area within unit time, unit expression is often l/m2·h.
• Trans-membrane differential pressure (TMP in short): The difference between water production side pressure and average pressure of raw water inlet and outlet.

TMP = (raw water inlet pressure + concentrate water pressure)/2 – permeate water pressure.

• Pollution to membrane: The process in which some of the components of liquid deposit on membrane surface or in pores and causes membrane performance degradation.
• Backwash: Membrane-produced water or high quality water is using to reversed washing for membrane fiber (reverse to filtering process), make backwashing water though membrane fiber to loosen and wash out pollutant which have kept on the membrane fiber surface during filtering process.
• Backwash with gas and water: Shake air to scrub the outer surface of membrane fibers at same time during backwashing process such that by shaking and scrubbing to the membrane fiber by air and water, the pollutant on the outer surface of membrane fiber is removed (a special procedure of only outer compressed membrane fiber).
• Chemical enhanced backwashing (CEB in short): Add certain of chemical agent into backwashing water to get rid of pollutant formed on the membrane during filtering process by backwashing and immerging of it.
• Cleaning in place (CIP in short): Chemical cleaning that the membrane module is not removed from skim.
• Recycling rate: The percentage of produced water and raw water, the

recycling rate=produced water /raw water ×100%.