Almost every industry will need pure water at one point or another. Pure water is just what it sounds like, 100% (or as close as science can come) water that is made of nothing but H20. This is easier said than done, as naturally occurring pure water is quite rare, so man has to step in and help it along. Two of the leading methods for water purification for industrial and commercial environments are Twin Bed Deionization (also called strong base demineralization or Two Bed De-Ionization or DI) and Reverse Osmosis (RO). While they obtain roughly the same results, choosing between them for your industry’s pure water can be difficult. We thought we would take a moment out to help you sift thought the mountains of information and find out which is the best match for your industrial water purification needs. Industrial Reverse Osmosis (RO) A relatively new technique, industrial reverse osmosis, or industrial RO, has only become widely available within the last two decades. Industrial reverse osmosis is a diffusion process that runs water through a semipermeable membrane against the concentration gradient, which in turn catches and removes ions and larger molecules. Today, commercial and industrial reverse osmosis systems are usually the preferred method for removing the majority of TDS (Total Dissolved Solids) in water. For polishing the water to ultra or a super high purity level, mixed bed deionizers (DI) or electrodeionization (EDI) is needed. For more information on the reverse osmosis process theory, visit our page on industrial reverse osmosis.
Pros of Industrial Reverse Osmosis
- Industrial reverse osmosis systems remove up to 99% of dissolved mineral salts, organics and other particles.
- No chemicals or permits are required with industrial reverse osmosis.
- Industrial reverse osmosis is a very environmentally friendly process.
- Capital and operation costs are usually much lower with industrial reverse osmosis systems than with industrial two bed deionization systems.
- Industrial reverse osmosis maintenance is easy and system operation is relatively low compared to twin bed DI systems.
- Industrial RO systems perform well in high TDS water.
- Industrial RO systems are great for desalination and removal of impurities like ethanol.
Cons of Industrial Reverse Osmosis
- Industrial reverse osmosis usually requires some sort of pretreatment equipment (e.g. industrial water softeners, ML or AG+ filters, carbon filters) or a small chemical treatment feed.
- Certain water chemistries do not work well in reverse osmosis systems (e.g. high silica or barium levels could cause scaling).
- Water needs to be temporarily stored and re-pressurized with industrial reverse osmosis.
- Incoming water with fine silt or other small suspended solids that are hard to catch in a pre-filter can lead to membrane plugging in industrial reverse osmosis systems. Industrial nanofiltration systems can be used, but are expensive.
- Industrial reverse osmosis equipment has a more limited temperature range than DI systems have.
Industrial Twin Bed De-Ionization (DI) As is clear from its name, de-ionization (also often written as deionization) is the process of removing ions from water. Twin bed de-ionization (or demineralization, as it’s sometimes called) is accomplished by running water through two ion exchange columns, first a cation DI tank and then an anion DI tank. One tank removes all the cations in the water and the other all the anions. For more information on the process theory, visit our Industrial Deionization page.
Pros of Industrial Two Bed De-Ionization
- Industrial de-ionization is a tried and true method that is widely accessible. It is perfect for certain water chemistry, temperature, and quality issues.
- Capital costs of DI systems with high flow rates can be much more cost effective than reverse osmosis with certain water chemistries (e.g. low TDS ~ 150-250ppm).
- Industrial de-ionizers can be used with higher temperatures than reverse osmosis systems.
- For some water chemistries, demineralizers (another name for industrial de-ionization) will perform better than reverse osmosis systems.
- Industrial de-ionization can handle a higher temperature range than reverse osmosis as well.
- De-ionization can handle a wider range of water chemistries than reverse osmosis equipment.
- Industrial de-ionization doesn’t usually require any pretreatment equipment (industrial water softeners, carbon filters, ML or AG+ Filters).
Cons of Industrial Two Bed De-Ionization
- Industrial de-ionization uses a process that can be dangerous to workers due to the use of acids and caustic chemicals for regeneration.
- Permits for the chemicals are often needed and having hazardous materials on site can increase insurance costs with industrial de-ionizers.
- Operating costs are usually much higher with industrial twin bed de-ionization systems.
- Initial capital costs for industrial de-ionizers are usually higher than with industrial RO equipment.
So, which is right for you: industrial twin bed de-ionization or industrial reverse osmosis? There is no fail-proof formula for making that decision; it really ends up being a case-by-case issue. The best thing to do is contact an expert to help point you in the right direction.