Production improvements through water recycling: how D.I. ion exchange pretreatment and electrodeionazation water recycling, or AEDI, can save resources and money. (Green Thoughts).

THE TYCO ELECTRONICS Printed Circuit Group puts circuit boards through multiple processes to clean, etch and then plate. The plant, located in Los Angeles, decided in January 2002 to assess a close-looped ECS cleaning line. (An ECS line provides a clean innerlayer core and coats this core with dry-film resist.)

Tyco investigated replacing its D.I. ion exchange pretreatment system with an electrodeionazation water recycling system known as AEDI. AEDI devices remove ionizable constituents from water using ion exchange membranes, ion exchange resins and a DC electrical potential. AEDI provides two technologies in one module: electrodialysis and ion exchange. Ion exchange membranes separate an ion exchange mixed bed from electrodes. The ion exchange resins remove ionic matter from process water and the electrodes provide electro-regeneration of the resin when energized by a DC rectifier.

AEDI applications include direct recovery of electrolytes from active rinses as well as recovery and recycling of process water and wastewater in industrial applications.

In the past wastewater and waste solutions from wet processes were treated to remove hazardous chemicals (especially heavy metals) by precipitation, flocculation and pH adjustment, and were then discharged to the sewer after meeting acceptable levels of publicly owned treatment works (POTW).

The facility had rising water and sewer costs due to the high use of water and wastewater discharge. In addition, water savings, lower sewer surcharge and the related connection fees were set to increase. The plant did not want to be subject to certain capacity units, which would have limited future expansion and operating expenses. The management looked for water savings through D.I. water recycling and at the same time to save the cost for off-site D.I. bottle regeneration.

Using novel AEDI technology for the ECS line, Tyco will save about 16 gal. per minute of water, and avoid all costs associated with treatment, disposal, raw water purchases and pure water production charges (DI bottles).

The utility cost after installation of AEDI for the ECS line is $12.29 per day for electrical and $3.50 per day for water make up.

The water savings are being measured by installing flow meters on each incoming and outgoing line to and from the ECS. The data for each line are fed to a central PC or other data acquisition device.

The 16-gpm AEDI system was installed in February 2002 and is producing water with zero to 1 ppm total dissolved solids (TDS). Four hours of monthly maintenance is required to keep the system in prime operating condition. The payback for the AEDI installation was estimated to be within one year. With a 16-gpm AEDI system the plant can save 50,000 gal. per year.

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DR. FRED REINHARD is VP of technology at Exergy Technologies (exergycorp.com). He can be reached at freinhard@ exergycorp.com. CHRISTIAN TASSER is an applications engineer at Exergy. He can be reached at [e-mail].