Foxconn Technology Group will invest in a $30 million zero liquid discharge industrial water recycling system for its planned manufacturing complex in southeastern Wisconsin, according to the Associated Press. Such a system will significantly reduce the amount of water drawn from Lake Michigan from earlier estimates, and reflects plans first reported in their water use application.
In April, the Wisconsin Department of Natural Resources approved a request from the city of Racine to draw 7 million gallons of water a day (mgd) from the lake to serve the $10 billion complex. Though local reaction was mixed, many raised concerns about the volume of water withdrawals proposed.
In Foxconn’s original application to the Wisconsin DNR, prepared by Ruekert & Mielke Inc., Waukesha, Wis., it was noted that of the 7 mgd, approximately 4.3 mgd would have been returned to the lake daily, with the balance of 2.7 mgd consumed by Foxconn for the manufacturing process and the cooling towers.
The original application document noted, “Foxconn intends to repeatedly recycle its process water. Recycling this water would significantly reduce the demand for this facility, lowering the volume of water needed from 20.6 mgd on an average day to 5.8 mgd. Foxconn would use a heat-exchange process to cool a separate, closed water-cooling loop. The heat exchange process would evaporate approximately 2.1 mgd and return the remaining 0.3 mgd to the Great Lakes basin via the Racine Wastewater Utility as blowdown water. If a zero liquid discharge system is used to process wastewater, the diversion volume will be substantially lower than the above estimates.”
Zero liquid discharge systems employ advanced wastewater treatment technologies to purify and recycle all wastewater produced. It includes pretreatment and evaporation industrial effluent until the dissolved solids precipitate. The precipitate is removed and dewatered while the water vapor from evaporation is condensed and returned to the process.