Case Study: Reject Recovery Reverse Osmosis Technology Selected To Reduce Water Usage
When CPF, Inc./Northeast Hot Fill Co-op, Inc. of Ayer, Massachusetts, U.S.A. wanted to minimize the cost of their water and sewage, while producing purified bottled water, they chose a system that included reject recovery reverse osmosis (RO) technology. The company had been using two independent single-pass RO treatment trains, which fed a product water storage tank. Each RO system operated at 75 percent recovery, and the remaining 25 percent was sent to drain. With reject recovery, the plant water system now operates at a recovery rate of over 90%.
The plant produces the Aquafina® brand of bottled water and about 80 different flavors of soft drinks, including Pepsi®, Diet Pepsi®, Mountain Dew®, Sierra Mist®, Mug® Root Beer, Tropicana Twister®, Schweppes® ginger ale, Dr. Pepper® and Lipton® iced teas. Approximately 150 people work at this plant that operates seven days a week, 24 hours per day. One of the largest bottlers in the U.S., the plant produced about 26 million cases of finished beverage in 2006; eight million cases of that was the Aquafina brand.
To meet the plant's water quality specifications, Northeast Hot Fill installed two single-pass RO systems, followed by continuous electrodeionization (CEDI). To increase the efficiency, they added a reject recovery RO system to treat the reject water from the primary RO systems. The product water from the recovery RO is producing water quality that is better than the city water. This recovered water is then sent to the plant's lime coagulation treatment system, and is eventually used as ingredient water for carbonated soft drinks.
The reject recovery RO system is fed with 23 m3/hr of water from the storage tank, which contains reject water from the primary RO's. An ultraviolet (UV) sterilization loop ensures a low microbial count in the tank. Antiscalant is added upstream of the RO to prevent scaling of the membranes. The RO product water (14 m3/hr) is chlorinated and sent to the lime coagulation unit, while the RO reject water (9.1 m3/hr) is sent to drain.
According to the plant's quality control manager, they are able to use the recycled reject in carbonated beverage production because the water quality is better than the product water from traditional lime coagulation treatment methods.
With the upgraded system, Northeast Hot Fill increased the water recovery rate from 75 percent to over 90 percent, and reduced the plant's water consumption by approximately 16 million gallons per year. Besides saving water, the system ensures that the plant achieves its bottled water specification for chloride. The company purchased a third primary RO system and carbon tower in 2005, and the product water from this RO is used for tea production, while the system reject is sent to the recovery RO system.
Says the plant's quality control manager, "We've been very happy with the system, since it's producing the water quality we need. I would definitely recommend reject recovery RO for a beverage plant that wants to reduce its water usage."