Outboard Marine Corp (OMC) is a manufacturer of boat brands such as Seaswirl, Lowe, and Javelin, as well as engine brands such as Johnson Outboards and Evinrude. The company' s Waukegan, Illinois, division is a die casting facility that forms many of the aluminum components, from large engine blocks to small parts, for OMC' s engine division.

Like any other manufacturing operation, OMC Waukegan's die casting process requires cleaning of equipment. The dies, for example, are coated with lubricants that act as release agents, and these lubricants must be washed off after use. A cleaning stage is also necessary whenever a die is changed on a machine, as it is for any routine maintenance done on the equipment.

The cleaning method used by the facility is power washing with an aqueous cleaning agent with a pH less than 12.5 to a visible level of cleanliness. The cleaning results in a waste effluent of agent, water, and a combination of floating and emulsified oils. Though this waste is non-hazardous, the cost of hauling it away was very expensive because of the high volume of water, about 300,000 gallons per year. Therefore, OMC  Waukegan sought to find a way to recycle some of that water for reuse in their operation.

Finalists for the Governor' s Award for a pilot study they did in conjunction with the state of Illinois, Waukegan was offered a grant from the state to look at evaporation technologies, ultrafiltration, and vapor recompression as methods for recycling their wastewater. Their findings pointed to ultrafiltration as a better payback in this application, with lower operation and maintenance costs, energy costs, and capital investment required.

Waukegan put these findings into practice with an Arbortech Corp (McHenry, Illinois) ultrafiltration system. The system was a success, reducing the plant' s yearly disposal of the soap and water cleaning solution from the 300,000 gallons previously hauled away to 50,000 gallons. This 83% recovery naturally spared the company great expense when hauling away their effluent. Anthony Montemurro of Waukegan said of the process change, "It works really well, and we've been doing it now for a couple years with significant reduction in cost."

Though they were only seeking to reuse their water, Waukegan found an added benefit in using the ultrafiltration system. They discovered that the membrane allows a lot of the cleaner to pass through, reducing the amount of cleaning agent they need to add to get their cleaner concentration back up to operating levels. Said Montemurro, "That was something we really hadn't bargained for, but of course, we weren't going to complain about it!"

The high rate of recovery from Waukegan's waste stream didn't particularly surprise Arbortech' s Ray Graffia, Jr. "In general terms," he noted, "with alkaline cleaners or phosphatizing degreasing solutions . . . you get some recovery of the cleaner that's involved." According to Graffia, that could be anywhere from 50% to 80% cleaner recoverability, and any components that are lost in the process can be made up with an additive package.

In optimal conditions at the OMC Waukegan site, the membranes are being cleaned from once a week to once every other week with hot water and a special cleaner. "Basically," explains Graffia, "they turn the system off the process, do a short flush, and then they turn it on the cleaning process." Furthermore, if a need arises for temporary maintenance between scheduled cleanings, the 1-inch-diameter internal dimension of the membranes allows them to be manually cleaned.