Sarah Moser

"If an odor exists in a municipal solid waste facility, and no one is there to smell it, is there really an odor?" wondered Ian Howard, vice president of Ecolo Odor Systems, Mississauga, Ontario.

Odor is a subjective issue, and controlling it effectively requires shielding a community from the stench while disposing of the odor in a convenient, environmentally sound process. To combat odor, everything from anti-smell facility designs to chemical products and mechanical treatments are being developed.

Naturally, all garbage emits the distinct scent of decaying materials, but the smell becomes more pronounced when waste is allowed to sit for more than 24 hours. Decomposition is exacerbated by factors such as content and regional climate.

In addition, the worst sources of odor in a municipal solid waste (MSW) facility, according to How-ard, are container loads of food waste, putrefied meats and fish and rendering waste. Of course, not every load of garbage removed from a customer's curb will contain these odoriferous substances, but all solid waste facilities must be prepared to handle any combination of smelly stuff.

Air Or Topical Treatments The waste industry's response to odor depends upon whether the facility is architecturally designed to eliminate odor or if it must rely on aromatic esters to neutralize odors. When the latter method is used, the facility manager can terminate odor either by spraying solutions into the air or by applying stench-quenching materials directly to the source.

Rather than merely masking offensive scents, most odor-control treatments use ion exchange or oxidation to in-terfere with the with the odor after it has been produced. By bonding with the odor molecule and breaking it down into its elemental compounds, the solution acts as a decomposition catalyst. The odorless molecules reportedly then disperse into the atmosphere. Throughout this process, the odor-control solution should not harm the environment.

Another option is a spray of water mixed with formulas that neutralize odors in the atmosphere rather than at its source on the ground. High-pressure atomization reportedly minimizes the amount of solution used, but allows the mist to mig-rate quickly be-cause it stays airborne. The ad- vantage of misting is that it does not significantly in-crease the MSW's weight or saturate it with excess liquid, according to Ralph Landano of AiReactor Inc., Maspeth, N.Y.

In addition, misting systems can cover large areas quickly and cost-effectively, which is key for outdoor waste sites such as landfills and composting facilities, according to Phillip Cranny, technical director at Odor Management Services, Minneapolis. Efficient application is essential. "Today's dispersion technologies allow odor to be controlled at a site's perimeter," Cranny said. "If the wind blows toward neighbors, the dispersion equipment is activated. If it blows out to sea, the equipment switches off - and saves money."

For Edward Shields, however, the wood yard supervisor for Resource Northeast, rapid dispersion was reason enough to invest in an AiReactor system to control odor.

Meanwhile, Bill Taylor, plant manager at one of four Waste Management Inc. (WMI) facilities in Chicago, found a misting system to be necessary for his indoor recycling plant. As part of the city's new Blue Bag curbside recycling program, milk jugs and other plastics are retrieved from the customers' doorsteps and taken to the processing facility's baling room. To prevent employees from being overwhelmed by the smell of sour milk, for nearly a year WMI has used an Ecolo misting system that intermittently sprays a deodorizing mist throughout the room.

Still, for various reasons, many MSW facility managers choose to sprinkle their waste with odor-controlling granules or powders. These odor-abatement materials can be dispersed by windsocks - or even a fire hose. Granulat-ed products also can be rolled into a landfill with a bulldozer; as layers are added, odors in the middle sections continue to be controlled, according to Barbara Lang, founder of Scottsdale, Ariz.-based Odor Control Co.

In addition, by sprinkling a granulated product - which AiReactor's Landano describes as "pigeon seed" - on the entrances and exits of MSW facilities, the odors from stray garbage are absorbed, and the granules can be swept back into the solid waste facility. For outdoor odor problems where the wind helps disperse the scent-prevention, the granules also can be an option.

Obviously, a facility's selected de-scenting program must fit its individual needs. While one facility that breaks down large quantities of construction materials might need a specialized dust- and odor-control system, another might have to remove a higher volume of liquids from its waste - without clogging drains or bringing the smell outside.

Finally, some waste companies may opt to control odor by oxidizing it on-site in their customers' compactors, according to Mike Schumer, division manager at Howe-Baker Engineers, Tyler, Texas. For example, systems may be installed in hospitals and high-rise buildings; to prevent odor from escaping from trash chutes, the New York City Housing Authority has installed Howe-Baker's ozone generators.

These not only reportedly destroy odor-causing molecules, according to Schumer, but they also reportedly retard bacterial growth, preventing fermentation and allowing trash to be stored for longer periods.

Creating A Line Of Defense Regardless of the odor-fighting tactic chosen, a facility manager's goal must be "modification," according to Lang. "When you mask, you are simply putting in a more intense odor than the original malodor." Lang also emphasized the importance of creating a barrier between the offensive odor and the potentially offended community. The best form of community relations, she said, is to avoid complaints entirely.

AiReactor's Landano agrees: "In the past, facility operators never really addressed ... odor problems until they received complaints from the community or from regulatory agencies, and, at that point, they didn't know where to turn." For that reason, it's essential for facility managers to familiarize themselves with their region's ground rules for controlling odors.

Indeed, considering the trend of urban sprawl, this approach has grown increasingly important. "As people move into the suburbs, living in beautiful, million-dollar homes, they are finding themselves closer to the plants that were originally built there to be away [from civic centers]," Lang pointed out. Assembling an odor-neutralizing line of defense is key to keeping the community happy - and the facility operating.

With that same goal in mind, some facility managers choose products that not only neutralize odors, but also deliver pleasant scents such as cinnamon, floral and citrus.

For example, Will Fullerton, plant manager at Wood Recycling in Peabody, Mass., knows first-hand the difficulty of shielding neighbors from the smelly truth. After trying everything from lime powder to disinfectant, Fullerton settled on Ecolo's misting system to create a barrier between the emanation and a nearby hotel. The situation had become so stinky that Fullerton opted to use a scented product to cover the stench during the few minutes it takes for the mist to react with the odor. "All you smell is this nice fresh purplish smell - like grape bubble gum." Although the hotel owner does not care for the grape scent, she agrees that it is better than ripe refuse.

Olfactory-Sensitive Facilities Another important odor-control tactic is facility design. Rather than waiting for the inevitable stench and responding to it with various treatments, properly designed facilities can help deter odor before it be-comes a problem.

From transfer station operators to truck drivers, almost anyone in the waste industry will agree that the most reliable method of odor control is very simple: keep the garbage moving and the facility clean. Stagnant refuse is a surefire source of the stench that will annoy neighbors.

"Transfer stations do not routinely receive complaints unless they have received a load of refuse that has been sitting in the trailer for a number of days and was exposed to the sun," said Eric Colville, an engineer at the Seattle office of SCS Engi-neers, Long Beach, Calif.

Unlike landfills or MSW processing facilities, transfer stations do not contribute greatly to malodor and litter problems. Because transfer stations tend to be relatively small and self-contained, controlling the unpleasant attributes is relatively easy and efficient, Colville said. For example, a simple odor control method is training a plant's operators in odor prevention.

Of course, facility design plays a greater role in odor control by preventing saturated solid waste from leaking wastewater out of the plant, spreading odors and potentially contaminating groundwater supplies. The first step in designing an olfactory-sensitive solid waste facility is to grade the site, which prevents precipitation from entering the building and mixing with refuse.

If excess liquid exists, a drainage system should be installed to collect the water without impeding the swift arrival and removal of solid waste. The water should be discharged into a sanitary sewer or directed to a holding tank until it can be removed to a wastewater treatment plant.

Another basic consideration when designing an odor-free facility is to ensure that the building does not have any corners or uneven surfaces, which can trap odor-producing materials. Clean, neat lines and smooth finishes on the walls help prevent decaying materials from congregating in the building's framework. Budget allowing, a concrete building is the best way to achieve the necessary smooth walls and seamless interior. If a metal-interior building is the only option, the plant operator must make sure that the walls are immaculate, Colville said.

Another key factor in design is the building's orientation. It should be turned so that the prevailing wind won't blow litter and odors in a concentrated stream downwind. Door-ways should be placed accordingly; if the building has an open front, it must be angled against wind.

In some cases, wind can work in the transfer station's favor because it effectively disperses odors; with a few hundred feet of buffer space between the stench-producing site and the nose, the wind can adequately dilute the odor. In the summer, the heat tends to make the odors worse; however, the increased windiness common on a warm day helps diffuse unpleasant odors. In the winter, odor is obviously less of a problem.

The best location for a transfer station or other MSW facility is as far as possible from the nearest sensitive neighbor. In a rural location, the facilities are placed at a minimum distance of five acres; a site handling a large urban community's waste should be at least 10 acres from neighbors.

Urban areas also require unique odor control processes, including appropriate ventilation. "In a fully enclosed transfer station, one [effective ventilation method] is drawing air down low through the side walls out to the top of the building. The offensive air is then blown into the atmosphere," Colville explained. "It works like a smokestack - it only has to go about 30 to 40 feet above the height of an average person" Of course, this simple method does not chemically alter the odor.

The Cost Of Control One major consideration when using odor-suppressing formulas is the cost. Fullerton said he can spend as much as $200 per day during the smelly summer months on odor control alone. As Colville pointed out, "If the facility were designed properly to begin with, you would not need to spend very much."

Clearly, the options for controlling odor at municipal solid waste facilities are diverse. Each method may be affected by issues such as budget, climate and existing facilities. At the heart of the odor control issue, however, lies community relations. Odors are less harmful than they are a nuisance, and it is the responsibility all waste industry members to maintain an odorless presence.

* AiReactor Inc. Odor control products, services and equipment. Contact: Ralph Lan-dano, 5 Railroad Pl., Maspeth, N.Y. 11378. (718) 326-2433. Fax: (718) 326-7179.

* Ecolo Odor Control Systems. Automatic, unattended airSolution atomizing systems. Contact: Ian Howard. 9-1222 Fewster Dr., Mississauga, Ontario. L4W 1A1. (905) 625-8664. Fax: (905) 625-8892. [email protected] or www.ecolo.com

* Nature Plus Inc. Ecocare biological odor control systems. Contact: Sheldon Murphy, 52 Lakeview Ave. #20, New Canaan, Conn. 06840. (203) 972-1100. Fax: (203) 966-2200. Reference: Richard White, Town of Fairfield Sewage Commission, 725 Old Post Rd., Fairfield, Conn. 06430. (203) 256-3003.

* Odor Control Technology Inc. Odor control consultants, equipment, chemical monitoring and solutions. Contact: Robert E. Gaubert, 2394 Monroe Dr., Gainesville, Ga. 30507. (770) 538-0350. Fax: (770) 538-0359. Reference: Wes Potter, Conagra, P.O. Box G, Greeley, Colo. 80632-0350. (970) 353-2311. Fax: (970) 353-2184.

* Surco Products Inc. Industrial and municipal odor control products and systems. Contact: Arnold Zlotnik, 292 Alpha Dr., RIDC Industrial Park, Pittsburgh, Pa. 15238-2903. (800) 556-0111. Fax: (800) 417-8726.

* Wheatec Inc. Bra-Vo odor control. Contact: Charles Stack, 25076 Orchard, Wheaton, Ill. 60187. (708) 682-3024. Fax: (708) 682-5337.

* Zep Manufacturing Co. Enviro-Chem Cx. Contact: Technical Services Dept., P.O. Box 2015, Atlanta, Ga. 30301. (404) 352-1680. Fax: (404) 350-6238.