In a reverse osmosis system an array describes the physical arrangement of the pressure vessel, e.g., 4:3:1 - 3 stages with 8 total vessels; stage 1 has 4 pressure vessels, stage 2 has 3 pressure vess [..]

An asymmetric membrane is one that is constructed of the same material (cellulose acetate or polyamide) which has an increase in porosity from surface to base. The surface has a dense thin barrier ski [..]

Brackish water is used in reverse osmosis systems. Brackish water is technically defined as water having TDS levels up to 6,000 mg/L, but is generally water that is too salty to be considered potable, [..]

The concentration factor is the degree that the RO feedwater dissolved solids are concentrated in the brine. Concentration Factor = 1/(1- Y) Where Y = Percentage recovery expressed as a decimal.

Concentration polarization refers to the concentration gradient of salts on the high pressure side of the reverse osmosis membrane surface created by the less than immediate redilution of salts left b [..]

An element or elements are often referred to as a "module". Elements are the physical devices that house the RO membrane. Spiral wound reverse osmosis systems can have up to six elements per [..]

Hydrolysis refers to the chemical breakdown of a reverse osmosis membrane from exposure to low or high pH, bio-activity and temperature. Normally associated with cellulose acetate membranes where the [..]

Nanofiltration is a process similar to reverse osmosis but it is less effective at removing dissolved solids. Nanofilters are commonly referred to as membrane softeners because they will usually rejec [..]

Osmotic pressure is the pressure required to prevent the flow of water across a semi-permeable membrane separating two solutions having different ionic strengths. For reverse osmosis systems it is the [..]

The term permeate is also referred to as "product" and describes the portion of the reverse osmosis feedwater stream water which passes through the RO membrane. Permeate = Feedwater - Concen [..]