Water treatment is not a core competency in food and beverage production. When manufacturers think of it at all, it’s usually because circumstances have conspired to make it too big a problem to ignore.
That moment arrived two years ago for Oland Brewery, when its wastewater discharge threatened to overwhelm the Halifax municipal treatment plant and force the Nova Scotia city to release water with levels of biological oxygen demand (BOD) and total suspended solids (TSS) into Halifax Harbor that would exceed national and provincial limits.
To build up a reserve if they were forced to upgrade the municipal plant, Halifax officials served Oland notice that surcharges would quintuple to almost $1 million annually, based on then-current BOD and TSS levels.
With a lineage dating to 1867 and 110 years on its current site, Oland Brewery is part of the fabric of Halifax and takes community stewardship seriously. “It probably would have been cheaper to pay the surcharge,” allows Wade Keller, corporate affairs-Atlantic for Labatt Breweries of Canada, which acquired Oland in 1971 (the Oland family maintains ownership of Moosehead Breweries Ltd. In Saint John, New Brunswick). Instead, the brewery is investing $13 million in an anaerobic digestion system that will eliminate surcharges and also generate enough methane to meet 5 percent of the natural gas demand for plant boilers. Commissioning should begin in December.
Labatt is owned by Anheuser-Busch InBev, so brewery engineers were able to draw on the expertise of corporate engineers in Toronto and St. Louis, the latter of which have overseen the construction of 10 biogas reactors at A-B breweries in North America. Still, outside expertise was necessary. ADI Systems Inc. in Fredericton, New Brunswick, was retained to wedge the reactor, sludge bed and gas drying & polishing equipment into a footprint that measures little more than a tenth of acre.
“When you can’t go wide, there’s only one other way to go,” observes Jose Molina, an ADI process engineer. Six tanks constitute the reactor, the tallest of which stretches 69 ft. high. With their polished steel skins, they could pass for beer storage tanks to the casual passerby.
A brewery’s waste stream isn’t particularly strong in terms of BOD, relative to other beverages, although Oland’s is stronger than most. Reuse of clean-in-place final-rinse water and other water-reduction efforts helped cut consumption 15 percent.
A common mantra in water treatment circles is “the solution to pollution is dilution.” Oland moved in the other direction, but it wouldn’t have it any other way. “In Canada, getting water isn’t a problem, but around the world, it is,” Keller points out. “Our company has a commitment to water conservation.”
Old problems, new solutions
Among water-treatment companies with a food and beverage focus, the most common anaerobic installations are dairy operations — fluid milk, cheese, ice cream, yogurt, etc. It’s true for Oklahoma City-based World Water Works Inc. and ADI, which has installed at least two dozen anaerobic reactors at dairies. GE Water & Process Technologies, Trevose, Pa., is eyeing that segment, as well, although much of its work to date has involved sugary streams from beverage manufacturers.
Oland’s space constraints were on the extreme end, but food manufacturers aren’t land barons, and space typically is a restriction, both inside and outside the four walls. GE has developed a soup-to-nuts portfolio of treatment options. The membrane bioreactor (MBR) is “our premier product and a game changer compared to gravity separation,” says Paul Schuler, region executive, the Americas-engineered systems. It also is a relative space miser.
“We’ve been doing beverage MBRs for years because their waste streams have super-high strength,” says Schuler. Systems can be either aerobic or anaerobic. The trend is toward the latter, because they not only generate energy, they reduce energy inputs compared to aerobic reactors. Less permeable tank liners and noncorrosive screws distinguish the anaerobic systems; the membranes themselves are the same.
GE’s showcase MBR project was Frito-Lay’s Casa Grande, Ariz., facility. Water recovery and reuse was a higher priority than biogas, and a 15-step process that includes low pressure reverse osmosis, starch recovery and activated carbon added complexity. Since project completion in 2010, the system has returned three-quarters of intake water back to the plant as process water – however, at an estimated cost of $13 per 1,000 gallons, only plants in the most water-stressed regions might consider undertaking such a project (Casa Grande is in the Sonoran Desert).
Most food processors are more interested in staying within the COD, BOD, phosphorous, nitrogen and TSS discharge limits set by municipalities and regulatory authorities. When conventional solutions are inadequate, they usually can turn to a supplier with an innovative new solution, often in a pre-engineered, skid-mounted format.
Daniel Dair, regional technical manager with World Water Works, says high organic loads can be a problem in Dissolved Air Flotation (DAF) systems. “They never build them big enough,” he complains, resulting in discharges that exceed permit limits. His firm has engineered a hydrocyclone that separates fats, segregating out lighter fractions and using the heavier ones to settle particulate in the DAF.
Prefiltering the waste stream is another option. Spiral Water Technologies Inc. in San Francisco is touting its skid-mounted self-cleaning mechanical filter. Particles in the 10-100 micron range are separated from inlet water, and a motor-driven spiral brush runs across the screen 10 times a second, allowing it to operate without a backflush.
“Sometimes the purge is an asset,” points out Ashwin Gulati, president and CEO. He recently demonstrated the unit for a processor of pomegranate juice. The firm was conveying a juice slurry by truck to a centrifuge to lower pulp content from 10 to 1 percent solids. His mechanical filter accomplished the job in one hour on site, in a single pass. Next up: a brewery trial.
A simple solution that doesn’t cost millions is preferable to a sophisticated energy- or water-recovery solution, but Oland has no regrets. Although its 937,000 bbl. finished goods capacity is dwarfed by its corporate cousins in St. Louis and elsewhere, the waste value stream is sufficient to eventually generate a return. In fact, GE’s Schuler estimates any brewery producing 300,000 bbl a year is a candidate for a biogas system. That’s more than all but a handful of craft breweries. A group of microbreweries in Bend, Ore., is considering pooling their waste and treating it in a cooperative MBR.
Regardless of whether those discussions bear fruit, food processors of all sizes can pick and choose from a wide range of solutions to a problem they wish would just go away.