Reverse Osmosis Treatment

Reverse osmosis (RO) is a water purification process that uses a semi-permeable membrane (synthetic lining) to filter out unwanted molecules and large particles. These systems filter out contaminants and sediments such as chlorine, salt, and dirt from drinking water.

In addition to removing contaminants and sediments, reverse osmosis can also remove microorganisms. RO gets water clean down to a molecular level, leaving only pure H2O behind.

Four Stages of Reverse Osmosis

Reverse osmosis typically involves four stages of filtration:

  1. A sediment filter
  2. A pre-carbon block
  3. Reverse osmosis membrane
  4. A post-carbon filter

The sediment filter removes the largest particles like dirt, sand, and rust to prevent clogging of the subsequent filters.

The pre-carbon filter uses activated carbon to prevent smaller particles from passing through as well as attracting and bonding with positively charged ions to prevent chemical compounds – like chlorine and chloramines – from passing through to the third filter.

The reverse osmosis membrane then removes molecules heavier than water, such as sodium, high levels of lead, dissolved minerals, and fluoride.

Finally, the post-carbon filter polishes the water.

Northstar’s RO Services

Northstar Chemical supplies the following, all approved for use in RO systems:

  • A variety of proprietary antiscalants and dispersants
  • “Clean in place” (CIP) chemistry
  • Biocides
  • Chlorination/dechlorination chemistry

In addition, your Northstar field engineer can size, design, and start up a custom reverse osmosis system for your facility.

Clean in Place Chemistry (CIP)

Our complete line of RO cleaning chemistry allows for either low pH or high pH CIP procedures and can remove:

  • Foulants like scale
  • Silt and sediment
  • Iron
  • Microbiological fouling

Your Northstar technical representative will evaluate the RO operations and incoming water quality. If necessary, the Northstar rep can conduct a membrane autopsy to identify the RO foulants and design a clean-in-place procedure that provides the best restoration of your reverse osmosis membrane.


Northstar reverse osmosis biocides are all approved for use in RO systems. A Northstar field engineer can evaluate your microbiological issues to see which biocide works best for you.

Applying biocides at the right injection point, at the proper concentration, and with the correct amount of mixing and residence time, is critical to get the best results. Northstar will work with your system to ensure our biocide works effectively to prevent and remove microbiological growth in your reverse osmosis system.


Northstar RO Antiscalants are a family of chemicals designed to inhibit the formation and precipitation of crystallized mineral salts that form scale. Most antiscalants are proprietary organic man-made polymers.

Engineers initially derived antiscalant technology for RO systems from chemistries used in cooling water and boiler water applications.

Industry engineers have developed a variety of antiscalant chemistries, which produce various results and efficacy depending on the application and organic polymer used.

Antiscalants retard the growth of crystalline salt structures in the RO feed and concentrate streams. Consequently, antiscalants allow a concentration of sparingly soluble salts in excess of the normal solubility limits.

Dispersants are a family of organic man-made polymers designed to inhibit the agglomeration and deposition of foulants onto the membrane surface. Dispersants are sometimes referred to as anti-foulants.

The efficacy of differing dispersants can vary for different foulants, so one needs to know what foulant they are treating for. Your Northstar field engineer will use a proprietary software package to determine optimal dosing and allowable maximum saturation levels of scalants and foulants for antiscalants/dispersants.

Proper Dosing for Antiscalants and Dispersants

Maintaining proper dosing levels of an antiscalant/dispersant is important. Under-dosing can cause scaling or fouling. Over-dosing can cause a deposition of the antiscalant/dispersant onto the membrane, creating a fouling problem.

Your Northstar representative will ensure your RO chemistry:

  • Is compatible with your RO
  • Doesn’t react adversely with any other constituents in the RO feed water (e.g. iron, heavy metals, cationic polyelectrolytes, etc.)
  • Is applied properly to keep the antiscalant or dispersant at the recommended dosing rate and does not exceed the maximum dosing rates

Trust your critical reverse osmosis operations to Northstar to ensure it operates at peak efficiency with no unnecessary downtime.

The reverse osmosis chemistry provided by Northstar Chemical meets the following certifications:

FDA, USDA, Kosher, Halal, non-GMO, GRAS, and NSF

For more information, visit our certifications page.