Water costs are a growing concern for produce processing facilities, who incur staggering expenses coming and going. On the intake side, large amounts of produce wash water are sent down the drain and have to be replaced by fresh city water. On the output side, the waste water contains high concentrations of BODs (biological oxygen demand), which incurs high surcharges from municipal wastewater treatment facilities.
It’s understandable that a new technology from American Water Purification, Inc. (AWPI) is attracting the attention of produce processing companies. It could save a large operation as much as $500,000 per year by jointly addressing the wash water and waste water problems.
“If you try to deal only with the waste water, it’s such a huge volume that it can’t be done cost effectively,” says AWPI CEO Dan Gates. “The water is cold when it leaves the wash water process, which means it would have to be heated before being sent to an anaerobic digestion process to remove BODs. This would add huge energy costs, and would require a massive equipment footprint. It just doesn’t make sense.”
AWPI has a solution that can save large produce processing facilities millions of dollars. It begins with the produce wash water process …
Reducing produce wash water costs
With current technology, some of the produce wash water is being recycled with a simple filtration system. “But it’s not enough,” says Gates: “They’re losing, on average, 20 gallons per minute, per line, and that volume has to be augmented by fresh, incoming water. This new water has to be cooled, which further increases costs.”
AWPI has designed an ozone/filtration system that reclaims 75 percent of the water that’s currently going down the drain. “We return it to the front end of the process so we cut energy costs as well as incoming water costs.”
GREEN NOTE: AWPI’s patented technology uses a four-stage ozone (rather than chlorine) process to purify and remove solids, BODs and CODs from process water. Ozone kills pathogens better than chlorine , but unlike chlorine, it generates no new toxins, carcinogens or pollutants.
“We’ve already applied a similar technology in the poultry industry with great success,” says Gates. “Ozone kills more pathogens than chlorine–and does it 3,000 times as fast. It has none of the storage costs or hazards, so it’s safer for personnel.”
Research conducted at the University of Georgia showed that ozone water showed no negative effect on the shelf life of lettuce.
Reducing BODs in the remaining waste water (no more surcharges)
After reducing the overall volume of waste water, new options are possible for the treatment of BODs. Anaerobic digestion is the technology commonly used by municipal water treatment facilities to remove BODs, but most produce processing facilities don’t have enough land space for the lagoons that would normally be required to do it onsite.
“After installing our produce wash water system at the front end of the process, the remaining volumes of waste water are reduced so significantly that anaerobic digestion can be performed in a 30,000 gallon tank,” says Gates. “This alleviates the need for a lagoon or large equipment footprint of any kind.”
AWPI’s system cleans the remaining waste water in several stages:
- Temperature equalization
- Anaerobic digestion of BODs
- Sludge removal
The remaining water goes back to the city with BODs reduced to less than 200 mg/L –which means no more surcharges. The non-haz sludge can be safely hauled to a landfill.
COST SAVINGS NOTE: In a cost study recently performed for a large produce processing facility, water cost savings with the AWPI combo system were calculated at $420,000 per year. Interconnect costs were estimated at $700,000, which indicates an interconnect cost recovery period of less than two years. After that, the savings go straight to the facility’s bottom line.
“We have some big players looking at this thing,” says Gates. “With the combination of green technology, improved employee safety, improved product quality and significant cost savings, this is a very exciting option for produce processing facilities.”
Learn more about the produce wash water technology.