ERLANGER, Ky., March 18, 2002 -- Since the installation of ultraviolet (UV) dechlorination equipment from Aquionics Inc., Procter & Gamble has reduced the cost of maintaining the reverse osmosis (RO) membranes at its Greensboro, NC manufacturing plant by $70,000 per annum. The number of shutdowns for RO membrane maintenance has also been significantly reduced.
"We are very pleased with the UV system," says Utilities Process Engineer Kurt Loughlin. "Not only have we saved money since it was installed, but the disruption caused by plant shutdowns as a result of RO membrane fouling has also been significantly reduced. UV provides a high standard of dechlorination without any of the drawbacks of using chemicals or GAC filters."
Chlorine is widely used for water disinfection in many different process industries. Because of its properties, however, it can damage delicate process equipment like RO membranes and deionization (DI) resin units and must be removed once it has performed its disinfection function.
High intensity, broad-spectrum UV systems dissociate both free chlorine and chloramine compounds (mono-, di- and tri-) into easily-removed byproducts. UV has the added benefit of providing both high levels of microbial disinfection and also total organic carbon (TOC) destruction.
At the Procter & Gamble facility, an Aquionics UV dechlorination unit was installed before two banks of RO membranes; prior to this dechlorination was achieved using sodium bisulfite. Trials run soon after the UV system's installation showed a dramatic reduction in the RO membrane wash frequency - down from an average of eight cleanings per month to only two per month - amounting to annual savings of $70, 000.
To date, the two most commonly used methods of chlorine removal have been granular activated carbon (GAC) filters or the addition of neutralizing chemicals such as sodium bisulfite.
GAC filters, because of their porous structure and nutrient-rich environment, can become a breeding ground for bacteria. Dechlorination chemicals such as sodium bisulfite, which are usually injected just in front of RO membranes, can also act as incubators for bacteria, causing biofouling of the membranes. In addition, these chemicals are hazardous to handle and there is a danger of over- or under-dosing due to human error.
Aquionics Inc. is a provider of UV technology for progressive, non-chemical disinfection and contamination control. A member of international environmental corporation Halma p.l.c., Aquionics offers nearly 20 years' experience in the manufacture, application and development of UV equipment.
