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Wine storage tanks tower over a winery in Bodegas Torres, Spain

 

With winemaking comes wastewater, a side effect that increases exponentially with the growing demand for the fermented juice of fine grapes. Table wine consumption in the US continues to rise after recently reaching a record high of 232 million cases per year. Consequently, winery wastewater management can be just as intricate as the formula behind the aroma, color, and bouquet of the most coveted selection in the cellar. Affected by far greater scrutiny from regulatory agencies and a neighboring public, as well as by energy conservation and sustainability needs, effective winery wastewater management has never been more important.

The caliber and popularity of a particular wine may present a challenging wastewater treatment scenario. Consider that as sales increase, wineries must expand their operations. Facilities will typically outgrow one wastewater handling and treatment method after another. Regulations continue to tighten and compliance becomes costly. Simple sewer connections are no longer feasible or even possible. The operation turns to septic tanks and leach fields only to find that the system becomes clogged with the high solids in the waste. The next step is the wastewater pond, which can tie up several acres of valuable vine land. The significant levels of dissolved sugars in the winemaking process are measured in the effluent as biological oxygen demand (BOD). With the “shock loading” of high BOD levels, odorous wastewater ponds can turn the noses of even the most passionate wine lovers.

So what’s a nice winemaker to do? Bottom line, treating winery wastewater requires customized, specialized solutions based upon specific factors at a given facility—such as its wastewater volume and seasonal load variation, its property size and available land, and its proximity to surface waters and residential areas. An operation’s current economics and future expansion plans also play a part.

But common to all wineries, regardless of size or situation, are the distinctive and highly fluctuating characteristics of raw winery wastewater. During the crush season, pH, BOD, total suspended solids (TSS), and nitrate levels are elevated. The seasonal nature of the business means that pH can range from 2.5 to 11, and BOD discharge levels may approach 5,000 ppm, with values as high as 20,000 ppm.

 
 

With all of these issues in the mix, many winemakers are collaborating with wastewater consultants, engineers, and system manufacturers to identify the most cost-efficient OWT technologies—ones that deliver a solid return by ensuring long-term environmental regulation compliance, while minimizing the treatment site footprint. Today’s forward-thinking wineries may also seek the cost savings from the reuse of treated wastewater for irrigation, or even the ability to create usable energy from the biogas byproduct of certain treatment methods.

Converting Ponds Into Bioreactors
Elutriate Systems of Arroyo Grande, CA, specializes in rapid BOD digestion wastewater systems, especially those that can maximize the treatment potential of a traditional pond system. “If we can’t make bigger ponds, let’s make the existing pond far more efficient,” says Glenn Wensloff, who heads the company.

Fine bubble diffusers are positioned at the bottom of the Hahn Estates Winery wastewater treatment pond.
Clos du Bois uses a Biothane high-rate anaerobic biodigester for faster, more efficient wastewater processing, and energy savings benefits.

Wensloff works one-on-one with wine makers and fruit processors to turn their conventional “facultative” ponding systems into effective “bioreactors.” He explains that facultative systems have three different layers based upon the aeration provided by traditional floating aerators. The top layer, with its high dissolved oxygen level, is where most of the BOD digestion occurs. The middle layer is a transition zone. The bottom layer is anaerobic, or devoid of oxygen. This is where the bacteria, which actually consume the BOD, are digested. “The facultative pond is a carryover from the sewer industry and, when fecal waste is involved, this process works well as it digests bacteria in a beneficial manner. But for the winery wastewater, it’s a poor design. In the wine industry, it is much more astute to view the bacteria from wastewater as a ‘compost tea.’ This is a beneficial non-fecal bacteria that is good for the soil and eliminates the need for both fertilizers and pesticides,” he says.

To meet the regulatory and operational requirements of a recent expansion at the award-winning Hahn Estates Winery in Monterey County, CA, Wensloff worked with the facility to ensure that its new ponding system would function as a rapid-acting aerobic digester, treating wastewater to the level where it could be reused and applied to the vines through a drip irrigation system. To accomplish that, the conventional floating aerators concept was scrapped and replaced with a fine bubble diffuser system that utilizes a blower to deliver high volumes of air at low pressures through diffusers, producing very small bubbles for greater operation efficiency. “The pond is now an aerobic digester with the aeration occurring on the bottom of the pond, and the entire pond volume rapidly digesting the BOD. The bacteria, which traditionally dropped from suspension, are now kept in intimate contact with the high BOD influent. The efficiency of the new system (which utilizes the existing footprint) increases tremendously,” Wensloff says.

Between the first two ponds in the system, Elutriate Systems installed a series of clarifiers that allow the bacteria to fall from suspension. Then the concentrated bacteria are pumped back to the incoming high BOD influent. The effluent flows from the clarifier into the second pond, which is also aerated with fine bubble diffusers. Treated effluent then flows to an irrigation pond where it awaits distribution as an irrigation system. Wensloff sums it all up when he says, “The more critters eating at the food basket, the faster the food is digested, and the smaller the system has to be. A lesser volume of water needs to be aerated, treated water is reused, and the savings quickly compound.”

As Hahn Estates continues to expand its market presence and winery production, its next wastewater system upgrade will involve placing a large bioreactor tank upstream from its ponding system, says Wensloff. “With a tank, it’s easy to get 20 feet of height. It’s hard to make a pond 20 feet deep. The increased depth you get from the tank allows for better oxygen transfer to the water, resulting in higher levels of dissolved oxygen and minimized electrical energy use,” he says.

 
 

Capitalizing on High-Rate Anaerobic Digestion
As a grape grower in Sonoma and Mendocino counties, Clos du Bois is recognized and certified within the sustainable farming community. In an integrated effort, says the company, it also utilizes environmentally sound practices at its winery, which is equipped with a high-rate anaerobic biodigester—the first wastewater treatment system of its kind at a California winery. When the operation quadrupled its production in the last decade to 1.5 million cases, its management chose the biodigester as a method of sustainable growth. It would require a footprint of 10,000 square feet, an attractive alternative to the multiple acres needed for large settling ponds. The biodigester, which holds 130,000 gallons at peak capacity, treats the same wastewater volume as that of a three-acre ponding system.

Manufactured by the Camden, NJ–based Biothane Corp., the biodigester uses anaerobic bacteria to break down grape skins and other matter within the wastewater, ridding it of much of its wastes within 24 hours. Treated water then flows to a traditional treatment pond before being used in vineyard irrigation. Although they incurred considerable upfront costs, Clos du Bois chose the unique solution, intending to reap its return in reduced energy costs year after year. Since its installation, the company says that the new system treats wastewater faster and more efficiently, while using less energy than that required by pumps in a pond system. But most importantly, the anaerobic digester produces methane gas as a byproduct. The next upgrade for Clos du Bois is capturing this biogas and reusing it to power other equipment.

“Anaerobic technology was developed in the Netherlands, with its first North American installation at a Wisconsin brewery in the 1980s. It has since been applied at yeast plants, ethanol plants, distilleries, and food processing operations—anything that uses fermentation in the development of the product,” says Robert Sax, Ph.D., president of Biothane. The problem with “conventional aerobic technology,” he says, is that it generates no energy byproduct, and much of its conversion process results in the production of biosolids, which is sludge that requires costly disposal. Among Biothane technology offerings are high- and low-loaded anaerobic systems, conventional and high-loaded aerobic systems, anaerobic sludge digestion and biological gas scrubbing.

Sax says that although advanced treatment technologies have always been more practical for larger winery operations, the economics of their use in smaller wineries are changing rapidly. “Due to skyrocketing fuel and energy costs, smaller operations will consider anaerobic technology more seriously than ever before. And, its high-rate digestion approach allows for a compact design. In the past, small companies couldn’t see the value in it,” says Sax, adding that under “old energy price scenarios,” even the largest wineries thought little about energy savings. “A lot of larger applications have simply flared the biogas, because there is a cost to recovering it for use. You have to pipe it, install a burner, and maintain boilers that accept controls. Even with that setup required, today’s market is taking a very hard look at it. Traditionally, companies were always motivated by an ability to cut wastewater surcharges. Now there is the additional incentive—valuable energy savings,” he says.

Writer CAROL WASSON owns JCL Marketing & Communications Inc.

 

OW - November/December 2005

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