Challenge

Emerging from economic and industry downturns, Elexsys faced increased demands coupled with cost management in a highly competitive printed circuit marketplace.  Elexsys, of Nashua, New Hampshire, needed a cost-effective solution that would reduce the hydraulic loading on their existing conventional wastewater system and allow easy expansion without sacrificing environmental integrity.  Ion exchange was investigated but then eliminated because it could not handle the high total dissolved solids load.  Other technologies, such as reverse osmosis, were examined.

Solution

• Elexsys worked with Siemens (formerly USFilter) to evaluate reverse osmosis for this application. 
• Extensive pilot tests were conducted to determine if reverse osmosis was feasible. 
• In March 1995, a full-scale 100 gpm rinse water recycle system using reverse osmosis was installed. 
• The system consisted of flow equalization, pH adjustment, bag filtration, granular activated carbon for clarification and oxidant and organic scavenging, ultraviolet sterilization to eliminate bacterial fouling, cartridge filtration and reverse osmosis.

Results

• The system recycles between 70,000 to 76,000 gallons of water per day. 
• The permeate quality averages less than 15 µS. 
• The company's annual gross saving after putting the reverse osmosis system in is $114,500. 
• Other benefits are a higher and more uniform daily temperature, delivery pressure and rinse water quality. 
• Because the flow and loading in the conventional treatment system are more even, metals precipitation is more uniform.
•  With the cost of the system and accessory equipment at $198,000, the expected system payback is just under 1.6 years.