Learn how antiscalants prevent mineral scale on reverse osmosis membranes, which minerals cause problems, and why correct dosing matters.
What Antiscalants Do in Reverse Osmosis Systems
As a reverse osmosis system produces treated water, the minerals left behind become more concentrated. Without protection, they can form scale on the membranes. Antiscalants help prevent that problem.
Why Scale Forms
The higher the recovery of a reverse osmosis system, the more concentrated the minerals become in the reject stream. At 75% recovery, that stream carries about four times the minerals of the feed water. When a mineral exceeds its solubility limit, it can deposit on the membrane surface.
Common Scale-Forming Minerals
Calcium carbonate
Calcium sulfate
Barium and strontium sulfate
Silica
Some of these, like silica and barium sulfate, are especially difficult to remove once they form.
How Antiscalants Work
Antiscalants are specialty chemicals that delay crystal formation and keep crystals from sticking to the membrane. This allows the concentrated water to leave the system before scale can develop.
Why Correct Dosing Matters
The right product and dose depend on the water analysis, the recovery rate, and the water temperature. Too little antiscalant allows scale to form, while too much can contribute to fouling. Antiscalants are usually injected before the cartridge filters with a dosing pump, so they mix completely before reaching the membranes.
American Water Solutions, LLC is a Texas-based company specializing in reverse osmosis water treatment systems for residential, commercial, and industrial applications.
