Zero Liquid Discharge (ZLD)

The total elimination of desalination plant concentrate and all other liquid waste discharges from a plant site. The end-product of a ZLD system is a solid residue of precipitated salts. Facilities most likely to practice ZLD are inland, brackish water


A watershed (or catchment, as commonly used internationally) is the area of land drained by a river or creek system. Higher land, mountains, or hills bound a watershed. If human activity is restricted or not permitted in the watershed, it

Wastewater or Used Water

This is water that has been used for domestic and industrial purposes and is discharged to a sewer. The wastewater from our homes is called domestic sewage; wastewater from industry is called industrial or trade waste (in England and Australia).


These do not have a cell structure with a nucleus like bacteria and are simpler and much smaller. Unlike living organisms, viruses are not able to take in food, get rid of waste, or reproduce by themselves. They direct their

Total Dissolved Solids (TDS)

The total concentration of all substances dissolved in water, often referred to as “salinity,” and measured in milligrams per liter (mg/L) or parts per million (ppm). Most dissolved solids are inorganic salts and minerals, although organic substances are also included.

Synthetic Organic Compounds

Specialty organic chemicals have been developed because they exhibit features that are valuable to us. They extend our life spans and enhance our quality of life. They include herbicides and insecticides, pharmaceuticals, food coloring and flavors, personal care products, dyes

Suspended Particles

Wastewater contains some particles that are suspended in water, rather than dissolved in it. They include fine particles of silt, organic matter, small organisms, and other insoluble matter. The presence of suspended particles causes water to appear cloudy and colored.


This is the general term for water from the sea or ocean. Typical seawater has a dissolved solids concentration, or salinity, of approximately 35,000 milligrams per liter (mg/L). Seawater is a chemically complex substance that may contain more than 70

Screened Wastewater

This is wastewater that has been screened to remove the large particles before  grit removal and settling to remove heavy grit and other settleable material to protect and enhance downstream treatment units. The screened wastewater is not of good quality


A condition that results when minerals precipitate from water and form a deposit on RO membranes, hindering the system’s performance. Scale formation can be controlled by proper membrane design and pretreatment.