PURE WATER PRODUCTION FOR INDUSTRIAL APPLICATIONS:

REVERSE OSMOSIS VS. ION EXCHANGE:

Electrocoat systems require clean water of certain criteria for the pretreatment final rinse, paint post rinse, and electrocoat tank. The ions introduced into these processes must be kept to a minimum, among other requirements. Normally, these criteria can be met by reverse osmosis or ion exchange (RO and DI respectively).

Comparison of RO vs. DI technology:

• RO purity is continuous while DI gets progressively worse as the resin nears regeneration.
• DI chemicals are expensive and therefore operating costs are higher than RO per gallon of purified water.
• RO membranes are a physical barrier that removes bacteria, viruses, algae and suspended solids while DI systems do not remove these contaminants.
• DI uses two hazardous chemicals, hydrochloric acid (HCl) and caustic soda (NaOH), for regenerating the resin beds; these chemicals have special storage and disposal requirements.
• RO systems have a continual concentrate effluent of 15-35%, but this does not require treatment before discharge to drain in the USA.
• RO systems produce pure water of 5-15 Microseimens. DI systems can produce pure water down to 1 Microseimens. Most pure water requirements can easily be met with RO systems.
• DI systems typically are marginally less expensive but RO systems cost much less to operate resulting in lower operating cost.
• DI resin bed life and RO elements life are similar at around 2-4 years. RO elements do not have hazardous disposal requirements.
• RO cleaning chemicals are not hazardous so they do not require special handling, storage or disposal procedures.
• RO systems are overall less expensive to operate and require less labor to maintain than DI systems.