Water Treatment

Hi,

My understanding is that RO is one of many techniques for purifying water. It is generally the most efficient method of water desalination, although each method has it's plus' and minus'. For example MED (multi-effect-distillation) is far more efficient if waste heat or cheap fuel is available.

There are many different methods to desalinate water, others include MED, MSF, H/D, EDI, EDR, Distillation, De-ionisation. I won't explain these, feel free to google them for better understanding.

Each method is suited to different feed waters, and each will produce different product water (depending oin the feed and system design).

Now to answer your question ...

RO Water is water produced via RO Desalination (and is often refferred to as permeate).

DM Water is water that has achieved a specific water quality. "DM" doesn't refer to the method of production. Simply that it is of suitable quality. DM typically stands for Demin (or Demineralized Water), and is typically of quality less than 0.2 -0.3 uS/cm (although each end user will specifiy what quality they require). This is extremely high quality, with the purest water at 0.055 uS/cm, compared to drinking water which is 300 - 600 uS/cm, and to sea water which is 50,000 uS/cm.

Demin Water is commonly produced via two pass RO (ie the water is processed through RO plant twice), then through EDI or EDR plant. It is often used in cooling tower / boiler feed (as less impurity means less maintenance and cleaning), and in semiconductor industry.

Sorry to babble on - to answer your question correctly ... unable to discuss the relative cost difference as this would entirely depend on you specific water supply, water requirments, etc.

As one responder has suggested approach the equipment suppliers. They will be able to give you a cost.

Hope this has helped your understanding.

Regards,

Anthony