Sustainability / Processing

Water’s rising tide

March 7, 2012
KEYWORDS CIP / wastewater / water
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During the come-up stage, 90psi steam is injected into a retort to evacuate any cold spots before sterilization begins. The step typically takes 15 minutes, during which time steam is vented through exhaust stacks to the roof. Allpax’s system replaces stacks for six retorts with a manifold that routes the steam to a vented tank where it condenses into water with a temperature approaching the boiling point. “It’s a giant pipe with a sprinkler system inside,” Jacob simplifies, and the energy recovery is the main advantage. The water savings are not insignificant, however: He calculates the system conserves 270 gallons of water from each cycle.

The industry’s most ambitious water conservation effort is playing out 1,700 miles southwest of Dubuque in Casa Grande, AZ, where Frito-Lay’s “near net zero” facility is targeting a 75 percent reduction in water use (see “Sustainable Plant of the Year,” Food Engineering, November 2011). Like Hormel, Frito-Lay introduced process changes at the chip facility, such as a corn-cook system that retains two-fifths of the water from each batch for use in the next. The star of the water management system, though, is the combination of multiple filtration technologies that leaves the corporate goal of a 20 percent water-use reduction in the dust.

The system’s workhorse is a membrane bioreactor (MBR) from GE Power & Water that recycles about 648,000 gallons of wastewater a day, replacing half the volume of municipal water that would be drawn. A carbon filtration system pushed reuse close to 65 percent, and it is augmented by low-pressure reverse osmosis (LPRO) technology that should push reuse to 75 percent. Carbon filtration was necessary to minimize fouling in the LPRO, which operates at pressures below 200psi. (Sanitary water is segregated and pumped to a nearby municipal treatment plant.) By the end of the process, total dissolved solids (TDS) are in the 28-40 milligrams per liter range, cleaner than the 400 TDS in the tap water.

“MBR use is growing rapidly” in both municipal and industrial applications, notes Yuvbir Singh, general manager in the water and process technologies division of GE Power & Water, Trevose, PA. Lower energy consumption and smaller footprints are encouraging companies to scrap clarifiers, activated sludge and other conventional treatments and replace them with newer technologies, including MBR and LPRO, he adds.

GE acquired several specialty suppliers of treatment technologies in the last decade, keyed by the 2006 purchase of Zenon Environmental, a Toronto area pioneer in ultrafiltration technology. Advances continue, and the tubular cross-flow filtration Zenon developed has given way to hollow fiber membranes that improve performance and erase the premium cost previously associated with MBR, says Singh. “We’ve caught up and surpassed conventional systems in operating costs.”

Frito-Lay’s system represents “a flagship application,” he adds, but technical refinements in just the last year are making new installations even more cost effective. For example, the newest R/O technology can slash energy demand from high-pressure pumps by two thirds. Manufacturers that might have improved wastewater treatment systems in stages now are implementing MBR and LPRO simultaneously. “For plants that have to treat their water anyway, payback is much faster if you can reuse the water,” concludes Singh.

Old machines, new tricks

Water availability is a growing problem in some regions, notably the Southeast, the center of US poultry production. Droughts in recent years have created occasional emergencies where plants were required to truck in water or temporarily close. Availability concerns have made chicken companies particularly receptive to water-saving systems that are simple and can generate a quick payback.

Packaging machines aren’t associated with water consumption, but in fact stretch-film tray packers used in poultry operations can consume copious amounts. Pro Mach’s Ossid division estimates its bread-and-butter case-ready tray overwrapper requires about 375,000 gallons a year to cool the rollers and sealing bars. About 1.5 gallons a minute course through hollow tubes in the sealing area, according to Ernie Newell, general manager at Rocky Mount, NC-based Ossid, and then is dumped down a drain. Ossid engineers adapted a simple water-recirculation system used in medical packaging for the industrial washdown environment and retrofitted hundreds of machines last year, Newell says.

A small compressor mounted under the machine drives coolant through a closed loop, picking up waste heat from the sealing zone and moving it through a fan-cooled radiator. “As long as you’re constantly cooling the water, it doesn’t pick up much heat,” even though the sealing bars operate in the 180˚ to 220˚C (356˚ to 428˚F) range, Newell explains. Very little coolant is lost, which is important from a functional standpoint. Vaporized water would condense in the sealing area, and that could compromise the integrity of package seals.

Most organizations hesitate to invest in new technology, and hydrolyzed water is a new commercial sanitizer that requires a six-figure expenditure to make it onsite. But the savings in chemical cleaners and water consumption are enormous, and recent improvements in the technology have convinced dozens of food and beverage processors to install the necessary hardware.

The core science traces to the 19th century, according to Chris Hoemeke, vice president-beverage sales for Trustwater Inc., St. Paul, MN, though only in the last decade have commercial systems reached the market. Refinements that make the output of sodium hydroxide and hypochlorous acid more consistent and the equipment safer to operate are even more recent. The science now is settled, says Hoemeke: “The FDA loves electrochemical activation.”

Dairy scientists were testing electrolyzed oxidizing water in CIP applications and general sanitizing seven years ago (see “Goodbye, elbow grease,” Food Engineering, March 2006), and two US dairies currently are testing Trustwater’s system. Water, salt and electricity are the only inputs needed for onsite chemical production. Hoemeke calculates the cost to generate a gallon of detergent and disinfectant at less than four cents, while an equivalent amount of commercial sanitizer costs $25 on average. Beverage production provides the quickest payback, and “the more flavor changes a day, the better the payback,” he says. One Trustwater installation paid for itself in one year in water savings alone, he claims.

But until there is a larger installed base, most manufacturers will shy away. Trustwater, with headquarters in Tipperary, Ireland, has fewer than 300 users worldwide, primarily at beverage companies and hospitals. North American firms are particularly risk averse: An Iranian facility owned by one of the world’s largest beverage companies purchased his system after a 20-day review, while one of the company’s US plants has been studying the system for two years. “It’s pathetic how long it takes,” moans Hoemeke.

Change takes time, however, and every new application must be analyzed before it is deployed. But new ideas that can be demonstrated to be more effective and more economical to operate eventually are adopted. The irony is that many of the changes taking place in food and beverage are being driven by a reconsideration of the worth of water, a commodity whose low cost long obscured its true value. 

For more information:

Greg Jacob, Allpax Products Inc., 985-893-9277

Mike Gruver, Diversey Inc., 641-455-6635, michael.gruver@diversey.com

Yuvbir Singh, GE Power & Water, 215-355-3300

Ernie Newell, Ossid, 252-446-6177

Chris Hoemeke, Trustwater Inc., 952-746-9880, chris.hoemeke@trustwater.com

Steve Willins, U.S. Energy Services, 502-814-7905, swillins@usenergyservices.com

 

Water audits for the other liquid asset

Most water audits focus on reducing the amount of water used in a plant. U.S. Energy Services auditors readily admit they probably won’t save a drop of water, but they can help curtail sewer charges.

The Minneapolis-based firm recently introduced a new monitoring and management service called H2O Oversight Service. Auditors look for billing discrepancies and other administrative overcharges.

The biggest source of overcharges is sewer-use fees based on the water that entered the plant, according to Steve Willins, account manager and new product development director at U.S. Energy. Most manufacturers are aware of this gap, and some “know exactly what is being discharged, and they don’t need our service,” he says. “But for many small and mid-sized companies, it’s simply a matter of not having the resources in house to document where the incoming water went.” That’s the audience U.S. Energy is targeting.

Water that goes into the product or is used for landscaping or in cooling towers, for example, never reaches the sewer system. But unless a manufacturer can document the precise amount of nondischarged gallons, the water utility likely will assess a sewer-use fee for those gallons, says Willins. Validating the amount of water that went places other than the sewer drain is the essence of U.S. Energy’s new service.
 



 

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