Concentrate

In water treatment and desalination, the term “concentrate” refers to the waste stream generated during the treatment process. When water is treated to remove impurities or desalinate it, residual streams or concentrates are produced, containing the unwanted substances removed from the treated water.

For example, in reverse osmosis (RO) desalination, a portion of the water is forced through a semipermeable membrane, producing purified water while dissolved salts and contaminants remain in the concentrate stream. This concentrate contains a high concentration of dissolved solids and salts and often requires further treatment or disposal to minimize environmental impact.

In pharmaceutical water treatment, concentrate can also be generated in processes such as nanofiltration or electrodeionization, where it helps remove impurities from treated water to achieve higher purity.

In practice, the terms concentrate and retentate are often used interchangeably.