As trash decomposes, it releases methane, greenhouse gases that contribute to climate change, and odors. The more organic waste present, the more bacterial decomposition takes place—and the more landfill gas is produced…which means the more odors are produced.
“Some of the toughest odor problems come from gas with low odor thresholds, such as sulfur-containing compounds—mercaptans and H2S, for instance,” says Shan Tao, Marketing Manager, Ecolo Odor Control Technologies. “These malodors, while they usually make up less than 1% of the malodor composition of a landfill, for example, are some of the most noxious odors detectable by humans, and largest contributors to nuisance complaints.”
“The most difficult odor control problems exist where it is physically challenging or costly to isolate the odor source,” says Tao. It’s also important to realize that odors can travel—not just in the air, but with the source material, from curbside to transfer station to landfill. But Tao emphasizes, “There are almost always preventive measures available to avoid the toughest odors, such as operational changes, as well as other strategies, such as developing community relations programs to help with mitigation. Programs and informational campaigns encourage effective communications between business and the communities they serve to find solutions together, and this is where Ecolo can help.”
Location, Location, Location
But all the blame for odors can’t be placed on the landfill. Landfills and MSW processing centers are not the only places where odor occurs. In addition to landfills and transfer stations, wastewater plants, food waste receptacles, garbage trucks, yard waste and food waste composting operations, sewer systems, pumping stations, and food waste bins at apartment complexes are sources of malodor.
“Odors are being emitted long before waste materials are processed or stored at a landfill or other MSW facility,” says Mike Lewis, odor control specialist for BossTek, a global leader in dust and odor control solutions for the storage and handling of bulk materials. Facilities that engage in food processing, composting, grinding, and recycling also face odor emission issues.
It’s important to know where the loads smell the worst. Measurement of offensive odors has grown into a significant business component in the environmental sector, creating new innovative technology to address the problem, according to Derk Maat, CEO, SciCorp International Corp. Drone-based sampling devices have been developed to measure odors above and around industrial facilities, for example.
Odors can sometimes originate at a transfer station or a food processor, particularly if the waste is in the hot sun and already decomposing, Tao says. Temperature and wind play a significant role by increasing decomposition and the spread of volatile organic compounds. When local residents spend more time outdoors in nicer weather, their exposure to airborne odors is increased—and so too, their complaints about them.
Remembering that odors can travel, Tao explains, “The odor transfers to the tipping floor with the waste, where it releases gases.”
To reduce odors and their transfer, Tao says it’s important to control them at the source. “Treatment closest to the source is best. Trade odors at the customer’s site by spraying the bins onsite with a handheld solution, for example.”
In early 2017, the Miramar Landfill in San Diego County, CA, was the target of numerous odor complaints with most of those complaints attributed to the compost operation. As part of the landfill’s comprehensive plan to address fugitive odors which included a unique biodegradable tarping system for the working face, Byers Scientific & Manufacturing was contacted to conduct a pilot program of its odor equipment and neutralizer.
According to Marc Byers, the CEO of Byers Scientific, “In early 2017, Byers Scientific staff deployed their Mobile Trailer-Mounted Vapor-Phase system at the site. The unit was selected due to its high degree of flexibility in terms of quick and easy deployment, ability to run 24/7 for up to five days off of its self-contained generator, and, importantly, its ability to be remotely monitored and operated.”
The unit was first deployed near the greenery but also moved to other areas of the site. Due to very favorable results early on in the pilot, the Miramar Landfill elected to purchase the unit as well as two more for deployment across the landfill’s footprint. A compelling factor in the landfill’s decision to purchase multiple units was the observed decrease in odor complaints. There were even comments from two unassociated local enforcement agents indicating their acknowledgement of clearly decreased detectable odors downwind from the unit’s deployment.
Control On the Go
Odor management must begin at the source. For landfills, that means the moment material enters the site. “In the past,” recalls Lewis, “many odor control strategies consisted of simply locating operations far from populated areas.”
Two recent trends have changed that dynamic. Managers and local officials now control operating costs by reducing transport, limiting land acquisition, and emphasizing environmental practices such as recycling and composting, often in operations located near populated areas.
The other trend is the expansion of growing populations that are now encroaching on sites that were once considered distant. “Remote operations are discovering they were not designed for extensive odor control beyond the typical practices of ground covering, foam treatment, or perimeter misting to distribute masking agents,” explains Lewis. These methods have proven moderately effective during downtime (nighttime and holidays, for example), but any time odor-causing material is unloaded, moved, or processed, success at controlling emissions is limited.
The customer needs to decide whether to neutralize or simply mask the odor, says Brian Singer, sales and marketing manager at Buffalo Turbine. “Basically, decide if they want the actual fix or putting [sic] a band-aid on the problem.” He says budget is sometimes the factor that influences managers to “help the problem rather than eliminate it,” but “once the local people, homeowners, or business[es] start complaining of the odor issue,” most landfill owners will address the problem.
“As suburban sprawl comes in close proximity or—in some cases—abuts the site line of MSW operations, new residents (a.k.a. voters) start demanding changes in odor management from operators and/or local officials,” continues Lewis. The complaints indicate the problem’s severity at specific times of day and weather conditions.
Singer believes that “a couple of machines placed in the right places” to harness the wind can “completely cover the areas causing the problems.” He says Buffalo Turbine machines would be the “perfect solution.” These portable machines are available in gas, diesel, and electric models, and cover an area of 35,000–40,000 square feet when the oscillation is set at 270 degrees.
The toughest situations involve trying to control odors at the source versus along the fence line, says Laura Haupert, director of research and development, OMI Industries. Source odors have high concentrations of gases causing the malodor: a mixture of chemical compounds that have to be treated. Depending on the application, the concentration of these gases can be in the thousands of parts per million, which makes them extremely hard to neutralize because the odor threshold for many odorous compounds is in the parts per billion. Therefore, treating situations where the concentration of gases is in the ppm range is a challenge.
Other issues making odor control difficult including changing elevation of the source (landfills); a neighborhood in a valley with the odorous source at a peak; thermal lift; wind speed and direction; temperature changes; and humidity all contribute to changes in the concentration of the odor and require different treatment methods.
High temperatures are a sizable issue for odor problems because an increase in temperature results in an increase in the concentration of the volatile gases causing the odor. Additionally, Haupert says, stagnant air can cause an increase in a concentration of gases over time. This can be an issue when a gust of air blows high concentrations of gases toward the neighbors. Therefore, when there are high temperatures and stagnant air, a large buildup of odors can occur. Once a gust of wind ensues, the high concentration of odors is pushed to the nearby neighborhoods, resulting in an increase in odor complaints.
Conditions where the wind direction changes can also cause an issue. “The key to odor control is having contact between the odor molecules and the natural plant-based odor control solution,” states Haupert. When the wind changes drastically, natural plant-based solutions still have to make contact with the odor molecules. “It’s imperative to have a solution for odor control that looks at all of these issues.”
Rain and humidity can also be factors, propagating microbial growth throughout the material and exacerbating the intensity and reach of the emissions. Lewis says, “An operation that is able to adjust to changing weather conditions is better prepared to address odor issues.” Many odor control experts correspondingly suggest revising material-handling procedures and utilizing specific types of odor control solutions for different situations.
Jesse Levin, NCM Odor Control president, indicates that air quality and dust problems in the waste industry are diagnosed a few different ways.
“Generally speaking, air quality and dust issues are not brought up until site workers start complaining or the company has an environmental manager and managing team that is truly thinking about the quality of the environment in which their workers operate,” notes Levin.
NCM’s permanent solutions come in the form of high-pressure atomizing systems, says Levin.
One of the systems offered is a fan misting system for outdoor projects or sites, where there is not a concern about the material getting saturated.
In some cases where the goal is to treat for dust onsite but ensure workers do not get soaked and the material is not over-saturated, NCM Odor and Dust Control has a high-pressure atomizing system that focuses on the source of the dust.
Meanwhile, there are currently several methods of treating odor that are highly effective. Most of the new technology being developed is based on the chemical breakdown of odors using UV, carbon, ozone, or biological filtration of odors. Other solutions include oxygenating and aerating solid and liquid waste collection basins to prevent septic conditions, but that is energy-intensive, Maat says.
Deodorizers can be an effective control agent for the majority of airborne odor emissions and malodorous source material and are usually dispersed as an atomized mist or vapor in microscopic particles. Biodegradable chemicals, which are safe for plants, animals, and humans, treat the odor on a molecular level by interacting with compounds such as sulfur or benzene, removing the odor-causing element and rendering it inert.
Foams and dirt cover can contain stockpiles until disrupted, but material movement can then release a large plume of pent-up odor, Lewis explains. “The primary benefit is that they are environmentally friendly and good for short-term storage.”
Chemical neutralizers block olfactory sensory neurons, dampening the ability to detect and discern smells. They block the sense of smell in humans and animals, but this can be disruptive to humans and detrimental to some species. In contrast, oxidizers introduce special agents, such as oxygen, peroxide, hydrogen peroxide, chlorine, or chloride into a substance in order to kill the bacteria that cause odor.
The ability to tower-mount atomized mist and vapor equipment for extended reach, more precise aiming, and wider coverage in order to address odor emissions from the top down is a new beneficial technology. The development of new, environmentally benign odor control chemicals has also been enhancing effectiveness without adding to total VOC emissions.
New equipment designs are also attacking odors with an engineered vapor rather than with water-based solutions, which delivers highly effective microscopic droplets while eliminating the need for a water source.
Ecolo AirPro vapor stations feature a wall-mounted control unit, multiple stations, and multiple zones. They are now water-free, Tao says, as are the vapor cannons, meaning they can be used year-round with no need for winterizing. The AirSolution formulas designed to neutralize organic odors reduce the intensity of airborne odors.
The cannon AOC is a self-contained odor control system that oscillates to cover 180 degrees. Tao expects the next generation will be portable. Designed for plug-and-play odor control, it can replace large water-based systems to address stand-alone and multiple odors.
Ecolo suggests a two-way approach to eliminate airborne odors by combining misting with the application of topical solutions to prevent the development of odors at the source.
Preventive measures begin with adopting a proactive approach and doing some research, Lewis says. “Most operations employ staff highly experienced in MSW management, but this may not include expertise in odor control.” He believes that a good first step is to reach out to local businesses that have similar odor issues. Each type of waste has unique odor properties, but creative solutions can often be found by consulting other operators and adopting or revising their approaches to enhance the odor management plan. “Observe other odor-emitting businesses in the area that contend with the same weather conditions and regulations.”
Regulations can be specific to certain molecular compounds, from sulfur to mercaptans to cadaverine, so recognizing the properties of the emissions and understanding the most effective treatments is important. Unfortunately, Lewis says, “many operations experiment with several makeshift options and become frustrated by ineffective methods. This approach has proven costly and unproductive.” He says bringing in an outside expert to assess the problem, implement proven solutions, and monitor progress is often the best way to control costs and optimize results.
However, education and understanding of the types of odor emission are key to choosing the correct solution. Trade shows, seminars, webinars, and other sources of information contribute to understanding odor control. Trade shows can provide networking opportunities and exposure to new techniques and technology, as well as one-on-one access to odor control experts.
For use at landfills, transfer stations, compost facilities, and recycling centers, Benzaco Scientific Inc. offers ODOR-ARMOR, a concentrated liquid that counteracts odors when diluted with water and fogged downwind, into the air through a series of pumps, hoses, and nozzles, or even high-velocity fans. Benzaco also offers linear odor management systems that do not require water, although waterless systems do not perform at the same level as water-based fogging systems, according to Rick O’Sadnick, senior scientist.
The ODOR-ARMOR system consists of two components: the liquid neutralizer and the water-based, high-pressure fogging units that disperse the neutralizing fog into the air. The neutralizer, which is 100% EPA compliant and biodegradable, is diluted and fed via a pharmaceutical grade chemical pump into a high-pressure stream of water. The nozzles, usually spaced every 15 feet, are installed along the downwind site perimeter.
“Typically,” says O’Sadnick, “ODOR-ARMOR is used as a finishing touch, a polishing agent, a final measure to take care of odors after other operational aspects of the landfill, transfer, or recycling site has been properly addressed.” Because various environmental and atmospheric factors affect the time of day during which odors are more prevalent, the system is timed accordingly. “On average, a site will program the odor control systems to turn on from 6 a.m. to 12 p.m., then again at 4 p.m. to 8 p.m.,” says O’Sadnick. That’s because the odors are more concentrated in the morning and the evening. The heat from the sun and the wind tend to disperse odors in the afternoon. “Also, people who are affected by the odors are at home more in the morning and evenings. But it all depends—there are some sites that run 24/7.”
While biocides kill bacteria that cause odors, they can also kill non-odor-producing beneficial anaerobic and aerobic bacteria responsible for the breakdown of waste material, and some of the compositions can be toxic to the environment. Formaldehyde, for example, is a biocide used to kill odors, but it is also a known carcinogen and inhibits biological processes.
Aerating wastestreams to biologically inhibit the activity of odor-producing bacteria is costly, energy-intensive, and tends to produce large quantities of new biological organic biomass, which, in turn, must be treated and disposed of, Maat says. This approach is only a partial solution because emissions still require treatment to generate odor-free discharge to the atmosphere.
SciCorp developed a new biological environmentally sustainable approach using plant-based organic micronutrients to specifically stimulate aerobes and anaerobes and inhibit the sulfur-reducing and ammonia-forming bacteria and enzymes: the BIOLOGIC SR2A/SRFmm. These micronutrients eliminate the formation of odors at the source.
According to Maat, the main active ingredients in micronutrient solutions include plant-sourced amino acids, vitamins, and other plant-based organic constituents and trace minerals. The micronutrient solution itself is biodegradable as it is used up by the beneficial bacteria as a food source found in organic wastestreams.
The micronutrient solutions inhibit the formation of hydrogen sulfide, ammonia, trimethylamine, methyl mercaptans, and other sulphur-reduced organic compounds.
Maat lists advantages with biological source control of odors with micronutrients:
- Elimination of the need for significant infrastructure and space requirements to contain, control, and treat odors
- Elimination of 90% of the capital investment associated with odor control using chemical and/or biofilter infrastructure
- Elimination of 90% of the energy demand associated with conventional odor control strategies and technologies
- A significant associated carbon footprint reduction. The use of plant-based organic micronutrient represents a near-zero carbon footprint solution.
Plant-based organic micronutrients can also be utilized in misting systems to treat odorous gases generated by nonpoint sources of odors in facility operations like transfer stations and landfills, Maat adds.
Options and Solutions: Future Technology
Innovation has led to ground-breaking equipment designs currently in the testing phase. Lewis believes these designs “will change how operators strategize and construct their odor management plans.”
Vapor cannons are versatile and easy to maneuver. Self-contained on a mobile carriage with an onboard generator, vapor cannons that require no water to operate are able to introduce billions of deodorizing droplets that address both ground-level sources and airborne odors. These invisible, biodegradable, and environmentally harmless chemicals interact on a molecular level to eliminate the odor-causing elements. Highly mobile and autonomous, once they are placed by a truck, skid steer, or other vehicles, a single worker can input settings such as oscillation arc and elevation.
Facility owners and managers are discovering versatile solutions and an array of options for odor control by incorporating different—and sometimes multiple—forms of technology.