Comprehensive understanding of the raw water quality and characteristics,
and type of water resource (e.g. surface water, brackish water,
seawater and industrial salinewater) is essential to select the appropriate
pretreatment technology ahead of the RO system. For instance, surface
waters have high turbidities, SDI, and NOMs as compared to water
from the well source due to adsorption and filtration effect on undergroundwater
reserves. Similarly,wellwaters contain high silica content
than surface waters. The initially large particles, whichmay be pumped
fromthewell, are removed fromthe feedwater usingmesh strainers or
traveling screens. Traveling screens are more useful for surface water
sources, which typically have large concentrations of biological debris.
The conventional pretreatment process may consist of all or some of
the following treatment steps: