Control and Mitigate

Evaluating and implementing technology and processes to improve our ability to control and mitigate the natural odors

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Advanced Disposal in Zion, IL—which primarily serves Lake County, northern Cook County, and southeast Wisconsin—takes in approximately 1,600 tons per day of municipal solid waste.

“Landfills play an important role in the management of waste generated by people and businesses across the county,” notes Jim Lewis, the landfill manager. “An important aspect of managing a landfill is reducing the odors that naturally come from the waste.”

Managers at Advanced Disposal “continually evaluate and implement technology and processes to improve our ability to control and mitigate the natural odors that come from the waste generated by the communities we serve,” adds Lewis.

Each odor has its own genesis and manifests itself differently at landfills, MRFs, and transfer stations. Dust also can present challenges at each of these facilities.

One starting point is in identifying the type of odor problem, with testing providing confirmation. New Waste Concepts identifies potential sources for pungent and putrid odors.

Pungent smells can include:

  • Ally Thiol – strong garlic, coffee
  • Ammonia – sharp, pungent
  • Benzyl Thiol – unpleasant, strong
  • Diphenyl Sulphide – unpleasant
  • Chlorine – pungent, suffocating
  • Chloro Phenol – unpleasant, penetrating
  • Crotyl Mercaptan – skunk-like
  • Dibutlyamine – fishy
  • Diisopropylamine – fishy
  • Triethylamine – ammonia, fishy
  • Ethylamine – ammonia-like
  • Butylamine – ammonia, sour
  • 1-Propanethiol – very strong onion
  • Pyridine – nauseating, irritating
  • Sulfur Dioxide – pungent, irritating
  • Toluene – Benzene-like
  • Acetaldehyde – pungent, fruity
  • Thiocresol – skunk, rancid
  • 2-Methyl-2-Butanethiol – skunk, unpleasant

Putrid smells can include:

  • Cadaverine – putrid, decaying flesh
  • 1,4-Diaminobutane – putrid, nauseating
  • Dimethylamine – putrid, fishy
  • Dimethyl Sulphide – decaying vegetables
  • Ethanethiol – decayed cabbage
  • Hydrogen Sulphide – rotten eggs
  • Indole – fecal, nauseating
  • Chlorophenol – medicinal
  • Methlymine – strong ammonia
  • Pentanethiol – unpleasant, putrid
  • Skatole – fecal, nauseating
  • Thiocresol – skunk, rancid
  • Thiophenol – putrid, garlic-like

As all organic materials eventually decompose, notes David Hill, CEO of GOC Technologies, “decomposition can be biological in nature as bacteria recycle nutrients and energy (carbon) from waste materials, but it can also be chemical and physical caused by pressure, temperature, and moisture even in the absence of biological activity.”

Decomposition creates a number of compounds; most of them are volatile and able to move from liquid or solid to gaseous states relatively easily, with many of them being odorous, Hill says.

“Conditions in the solid waste industry are perfect for odor formation,” says Hill. “Waste materials sit in bags and bins. Then they undergo pressure and stress in packer trucks, transfer stations, and transfer trucks and ultimately get exposed to oxygen, wind, and more pressure and stress at the landfill.”

Most of the odors created in waste materials are volatile organic compounds, including organic acids, mercaptans, aldehydes, ketones, and a host of other compounds, notes Hill.

“There can also be sulfides and amines. Some compounds have lots of chemical bonds and are very difficult to impact. Some are heavy. Some are very light. Some are acidic and some are alkaline. Some are negative and some are positive in ionic charge,” he adds.

All of those differences make treatment complex and difficult because different odors will travel differently—higher, lower, faster, slower, Hill says.

“Consequently, mitigation often requires a combination of different technologies and products. Sometimes landfill gas can be a problem as well, containing a variety of potentially odorous compounds.”

P. D. Dale, president of Bio-Organic Catalyst, notes that odors are almost always associated with anaerobic biological conditions, with their neutralization achieved by “shifting these conditions to an aerobic state through a transfer of oxygen into or onto the offending material or liquid,” he adds.

Odors can originate from solid waste dumped and spread on a landfill’s working face before it is covered, landfill gas, waste vehicles waiting in the queue to dump, and operational activities associated with landfill repair and maintenance, notes Marc Byers, CEO of Byers Scientific & Manufacturing.

An increased emphasis on separate collections of organic wastes in tandem with the development of neighborhoods closer to what at one time used to be remote MSW operations amplifies the challenge, he adds.

The conditions that lead to odors can be the opposite of conditions that lead to dust emissions, notes Ray Kapahi, senior air quality engineer for NCM Odor Control.

“Compacting of MSW at a landfill leads to the formation of sulfur and ammonia-based compounds such as hydrogen sulfide, dimethyl sulfide, and ammonia,” he says.

At composting sites, ammonia is most prevalent while sulfur-based compounds occur when dealing with MSW, Kapahi says, adding that high moisture is generally associated with excess odors.

Dust is generated as a result of material handling of low-moisture, high-silt content materials, Kapahi notes.

“With a truck dumping a load of MSW versus C&D, the MSW will generate some dust due to the high level of material handling even though MSW has a relatively high level of moisture—typically 70% for food waste but much lower moisture content for paper, cardboard, and soil. The C&D material is usually drier and contains items like drywall,” he adds.

While odor and dust are most often the product of operations or material processing, they also can be attributed to a facility’s building structure, notes Shan Tao, Director, Head of Sales and Marketing, Ecolo Odor Control Technologies Inc.

“Since there is relatively little mechanical processing at a multiple-stream MRF, these facilities are less prone to generating emissions of odor and dust,” she says. “However, the mixed waste of single-stream MRFs create additional processing and can include highly odorous organic waste. When dust is also involved, odors become worse and very difficult to measure.”

Environmental conditions also can affect odors, she adds.

“The high temperature and humidity of summer days is when human noses are at their most efficient and also when there [are] more odor molecules present in the air,” points out Tao. “This means odor issues, while they are present year-round, can be particularly noticeable and problematic in summer months.”

Worker safety—as well as equipment corrosion—are among the problems dust and odors create, says Dale, adding that it’s an “indication that the biological conditions are anaerobic and therefore not at peak conversion efficiency as anaerobic biological conversions are up to 1/30th of the speed of aerobic conversion rates.”

Odors and dust particles can be a simple nuisance, can cause temporary symptoms such as headaches and nausea, or can be toxic and cause serious harmful effects on the environment or the health of people and animals, notes Tao.

“Some people are more sensitive to environmental odors than others, but in general, as odor concentration levels increase, the more people will have adverse reactions such as headaches, nasal congestion, eye/nose/throat irritation, and nausea,” she adds.

“The intensity of reactions depends on the type of substance, the odor concentration in the air, the individual’s length of exposure, and his or her health condition and age.”

Odor and dust can cause issues with worker safety as well as with the general surrounding public, which in turn can lead to poor relations if mitigation steps are not taken or communication between facilities and the public isn’t open, says Tao.

“Development and expansion leave MRFs, transfer stations, and landfills in ever more vulnerable positions,” adds Hill. “Complaints can lead to fines and lawsuits and can cause major difficulties when there’s an expansion of existing sites or creation of new locations is necessary.”

Jesse Levin, president of NCM Odor Control, concurs.

“In some cases, odors and dust can present a health hazard,” he adds. “Both dust and odors prevent residents in the use and enjoyment of their property. These issues can lead to communities organizing through social media or community meetings and in cases that are really bad sites, companies can be dragged through class action lawsuits.”

The facility type—MRF, transfer station, or landfill—often will dictate the type of odor and dust problems that can occur.

Base odors emanating from a landfill are the result of biological and chemical processes taking place in an environment of moisture, heat, and pressure, according to Milton Knight, CEO, New Waste Concepts.

In an anaerobic (low oxygen) reaction phase, the biological processes release methane and carbon dioxide gases that slowly make their way to the landfill surface.

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Other odorous substances resulting from materials in varying states of decay compound odor problems as they rise to the surface, attached to the methane molecules.

Hydrogen sulfide, mercaptans, and ammonia are among some of the odorous and toxic gases produced in a landfill.

Hydrogen sulfide, dimethyl sulfide, and carbon sulfide are fugitive odors—odors released from open, unconfined areas as opposed to odors being released from a stack, notes Kapahi.

The most common and easily identifiable odor problems in a landfill occur at or near the surface, says Knight, with moist and wet materials emitting substantial amounts of odors as the moisture evaporates.

In transfer stations, odors mostly come from the breakdown of the waste in its early decomposition stages as the odor molecules escape from the waste on the floor and in areas where the waste is being loaded onto rail cars or on waste trucks prior to transport to the landfill.

Recent technological breakthroughs are enabling solid waste management operations to mitigate odors more effectively than ever.

“Currently, using gaseous deodorizers to fight odors—using gas to chase gas—is one of the newer, more effective methods of odor mitigation,” says Hill. “This is critical as all gases are several hundred times lighter than any liquid or solid.”

While many non-aqueous or vapor systems may currently work quite well, it provides “lots of room for more research and growth,” notes Hill.

“As new and more reactive gaseous deodorizer molecules are designed, it may be possible to have different weights in the same product, making it possible to contact heavy gases such as hydrogen sulfide and light gases such as acetaldehyde with the same treatment,” says Hill.

“Work is also underway to develop pre-treatment products—products that would be applied prior to the landfill that would limit odor formation in the waste for extended periods of time.”

One recent breakthrough in research and technology is the addition of a bio-organic catalyst into the leachate circulating liquid to optimize the methane production, says Dale.

“It’s much like better mixing being essential to anaerobic digesters meeting optimal methane yields and quality,”he adds.

Bio-Organic Catalyst provides “spray systems for transfer stations and MRFs and in landfills, we recommend adding the bio-organic catalysts to the water truck, which is used to wet the landfill cells,” says Dale.

“The addition of a bio-organic catalyst to the circulating leachate system can offer both accelerated breakdown action, higher and better quality methane from the landfill gas extraction, and generally help keep open the landfill fill material which can get highly compacted and problematic for good water penetration,” he adds.

Kapahi notes that the control of fugitive odors relies on a few factors. One is the use of odor control systems such as liquid misting systems and vapor-based systems.

Another factor is the location of odor control systems.

“This is dependent on the odor control company and the landfill identifying the areas that need treatment and designing a proper dispersion system to treat odors,” he adds.

Operational practices are another factor and should include how and where odor control is used at the site, Kapahi says.

“In our experience, most sites need to have a multi-tier approach and work in coordination with the site’s operational team,” says Kapahi. “Landfills have a combination of landfill gas and standard odors commonly found with MSW. Either a high-pressure atomizing mist system and/or vapor odor control system will provide good coverage at a landfill.”

The vapor systems NCM Odor Control manufactures are designed to work optimally with landfill gases, says Kapahi.

“Most vapor units are low-lying to the ground, emitting neutralizer in the air path that landfill gases tend to take,” he says. “These systems require the neutralizer to be evaporated and use air to push the neutralizer through piping that emits it through holes strategically placed and sized based on the linear footage each system is treating.

“Both atomizing mist systems and the vapor system approach rely on the odors mixing with the neutralizer in order to achieve odor control. This means that the odor neutralizer delivery system is as important as the neutralizer.”

Landfills also have leachate/aeration ponds that generate a fair amount of odors, Kapahi points out.

“For that, NCM manufactures an enzyme-based product that is added into the water,” he says. “Results show that contents like ammonia are reduced greatly, which aids in reducing odors. This type of treatment also is dependent on if the site has aeration in the pond to help generate a higher dissolved oxygen content to help ensure that the enzymes stay alive.”

The level of odors from many gases can be neutralized in the air through pneumatic systems or technologies such as Ecolo’s AOC Vapor Cannon, a self-contained odor control system using waterless XStreme Solutions in vapor form, says Tao.

The AOC Vapor Cannon has been designed for plug-and-play odor control operation and can be used to replace much larger, water-based systems, Tao adds.

“This feature allows it to be used in different applications, all year round,” she says.

Problem surfaces—from working exteriors to access roads, tipping pads, storage bins, and building interiors—can be treated through topical formulations such as Ecolo’s BioStreme solution, which is designed to prevent odors from developing, thus combatting odor problems directly at the source, says Tao.

Additional mitigation can include facility, machinery, and operational changes or the implementation of community relations and communication programs, she adds.

“Technology in the field is advancing rapidly,” says Tao, adding that Ecolo’s AOC Vapor Cannon is waterless and can be used where water supply or winter weather can be an issue.

Benzaco Scientific, the manufacturer of Odor-Armor, recently expanded its Vapor-Phase waterless odor management delivery systems designed with SCADA-based automation, remote management, and cost efficiencies.

The new system uses the waterless forms of Odor-Armor and is not diluted prior to application. They are designed for year-round applications, locations with water restrictions, or where conventional fogging is not suitable.

Benzaco’s Odor-Armor solutions deployed into the air through fogging as waterless vapor or applied topically at the source are designed as a cost-effective tool in solid waste odor management practices.

They are available with or without top note scent and compatible with most existing fogging and waterless vapor delivery systems.

In formulating the Odor-Armor product line, Benzaco uses a multi-component blend of naturally-occurring compounds that have a natural propensity to eliminate foul odors, says Rick O’Sadnick, senior scientist, Benzaco Scientific.

“They are designed for use around people with one of the industry’s highest health and safety profiles and do not contain solubilized nutrients or metals that can coat hard surfaces and compromise equipment,” notes O’Sadnick.

“We began using the Byers-Scientific system because it is a vapor-based neutralizing system which allows us to use the system during subfreezing temperatures,” notes Lewis. “Additionally, I believed the system would provide better mixing of the neutralizing compound with the odorous molecules.”

In addition to being able to operate the Byers-Scientific system during the winter months, other benefits Advanced Disposal is deriving include the efficient use of the neutralizing agent during changing weather conditions by allowing remote control of the system, says Lewis.

“This system does not rely on nozzles used by water-based systems,” he adds. “Eliminating the need to replace these nozzles makes the system more reliable and reduces maintenance.”

Odor neutralization is predicated on physical contact, says Byers.

“The neutralizing agent must come into physical contact with the malodor in order for a reaction to occur, resulting in the malodor being fundamentally changed and thereby unnoticed,” he adds.

Vapor phase technology represents the evolution of odor control as a neutralizer in the same physical state as the odors, which are themselves in a gaseous state, says Byers.

Byers Scientific & Manufacturing technology creates vapor independently of the distribution/delivery system in a constant, measured, and controllable manner and utilizes onboard sensors, flow meters, and other measuring and controlling devices.

System sensors are designed to detect odor control-related factors, enabling operators to respond proactively to real-time alerts regarding low deodorizer levels before odors manifest.

A weather report can be generated from the system at a preset time providing data regarding weather conditions, wind speed, and other factors that can be overlaid with how the system was operating at the time.

The system is designed to remotely operate the equipment and provide immediate reporting on any mechanical or day-to-day operational issue.

The Byers Scientific vapor system hardware is available in a fixed system and a trailer-mounted mobile system.

Site data such as air temperature, air dew point, site elevation, and site latitude and longitude are used to size the fan for the vapor system. The distribution pipe size, material, and length are considered as well as the number of holes in the pipe.

The Byers Scientific & Manufacturing vapor system broadcasts its data via a cellular router through a BSM VPN server, sending SMS/text and email alerts regarding reminders and critical events to key personnel.

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The weather station is integrated with the BSM SCADA system, requiring no additional hardware or software.

At the Byers Scientific & Manufacturing customer service monitoring center, the transmitted data shows system details with certain setpoints established to assist key personnel in solid waste operations to make necessary decisions.

The company’s dedicated SCADA system is custom-built to serve as the interface between its office and field systems. Every unit has a Programmable Logic Controller.

Should a site have ­particular odor issues in a typical time period, the unit can be programmed to increase its production to 150% for that peak period and then idle down and back up as needed. ­Scheduling also can be tied into a weather station.

Ecosorb 607, a deodorizer manufactured by OMI Industries, is specially ­formulated for Byers-Scientific waterless vapor odor control systems. It does not require added water. The dry vapor is designed for increased effectiveness as it “surfs” with malodors, as odor neutralization is predicated on physical contact, says Byers.

Ecosorb 607 utilized in a vapor phase through the Byers Scientific & Manufacturing system is designed to operate in below-freezing conditions in climates where high-pressure misting systems are unable to perform.

“The best solution for odor control on a landfill is effectively gas collection,” says Knight. “It’s probably the most expensive alternative, but it’s the most foolproof. There are other elements that occur at a landfill and those relate to a working face—managing your working face to keep your working face down as small as you possibly can is important.”

Additionally, providing good daily cover is important and a key to odor control, Knight adds.

“Those odors oftentimes come from the evaporation of moisture that is occurring at the surface level of the working face,” says Knight. “Stuff that had been stored in cans and transfer stations in high heat can be pretty odorous or a train can be sitting in a yard for five days and they’ve got to unload it and it’s a disaster. That material becomes volatile. All of those organics and gases have escaped as you’re putting this stuff on to the surface.”

In applying a good alternative daily cover, Knight cautions against diluting it or “just painting the surface with some thin liquid. It may control blowing litter, but it’s not going to do much in terms of controlling odors.”

NWC utilizes a rotary misting system that’s electrically- or hydraulically-driven. Knight notes that the system is designed to provide variations in droplet size and volume going through the system as well as the amount or percentage of the active solution as the situation mandates for either odor control or dust control.

“Dust control inside of a building is really more of an issue about control of the droplet size and the amount of liquid that you’re putting into the system,” says Knight. “It’s about how you disperse those droplets in and around an area that’s creating a lot of dust which is typical for a transfer station. You get to a landfill in which you’re trying to control fugitive dust which is either controlling dust on a road or up the side of a hill.”

NWC uses a dust control material that blends an acrylic polymer and a vinyl acetate, which is mixed with water and dispersed through a water truck onto the surface.

“It soaks into the ground and congeals, taking the surface of the dirt and creating that as the cover material,” notes Knight. “It can be used to minimize water intrusion into the landfill. We’ve seen a number of cases where it has cut down on the volume of leachate going into the landfill by almost 25%.”

Bacteria and enzyme technologies utilize and enhance the processes of bacteria in consuming organic matter. NWC uses bacteria that not only feeds on organic matter to help accelerate decomposition but competes for the organic food sources that other odor-causing bacteria consume, he says.

NWC’s bacteria derive nutrition for growth and reproduction without expiring odorous compounds. While the waste undergoes complex chemical and biological reactions and is metabolized into a final metabolic waste material, the beneficial bacteria continue to reproduce and emit both methane, carbon dioxide, and some other gases. As a result, bacteria and enzyme technology can be used to accelerate stabilization of the landfill and front-load the production of gases in landfills and bioreactors.

NWC’s chemical odor neutralizers are made from blends of food and cosmetic grade chemical compounds and special botanical derivatives. They typically contain less than 1% by total volume of the concentrate of commonly-used essential oils.

They work by chemically reacting with odor-causing molecules under a variety of ambient conditions. The products target alkaline and acidic-type odors and chemically react these species into insoluble salts that can precipitate out in the leachate. Each product is designed to address targeted odor mitigation needs.

NWC offers several options to apply and disperse its line of chemical odor neutralizers, including mobile, fixed, and integrated application platforms. Fixed applications include fixed nozzle systems and electric rotary head fixed systems.

Mobile application platforms include a simplified odor sprayer and SWAT Technology—Sprays Wide and Terminates—designed to effectively vaporize odor targets using bacteria and enzymes or odor neutralizing products.

SWAT Technology comes in three forms: the TF Series, which uses a fan system similar to a jet engine to cover a large area with NWC’s odor control products; the RF Series, which uses a standard rotary head fan to help disperse the odor control products; and the FN Series, a fixed nozzle system that can be permanently placed in an area, where it creates a fine mist.

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