Water often contains unwanted substances – “dissolved solids”. Dissolved solids are defined as those smaller than 0.5 micron. They cannot be removed by sand filters, dual-media filters or by multi-media filters. Removing them requires the use of membranes or media that are “activated”. There are a variety of activated media, such as wood (soft & hard), coal, coconut shells, peats and others. Each tailored to the removal of one or more specific dissolved substances. They work via adsorption, absorption or ion exchange, and must be replaced regularly.
In all, these media can remove more than 200 dissolved substances.
Examples of dissolved substances often found in water sources such as ground water, river water include:
- Hydrogen sulfide
- Unpleasant taste
Wastewaters often contain dissolved substances that need to be removed before discharging or re-using. Common examples include:
- Soaps & surfactants
- Heavy metals