Over the past few years, cannabis cultivation has quickly worked its way into the mainstream following its legalization in many U.S. states, throughout Canada and elsewhere in the world. However, successful participation in this emerging industry is still far from straightforward.
Growers spend a great deal of effort selecting optimal locations for their greenhouses and preparing these enclosed environments for ideal growth conditions. But one of the most frequently overlooked considerations is often the pungent odors produced by cannabis plants, especially when in the flowering phase. In fact, the smell produced during this time can even carry to residential and commercial neighborhoods several miles away from grow facilities.
Given the impact the surrounding community has on the success of a business, in cannabis cultivation as well as in other industries, the topic of odor abatement deserves more attention. While many companies attempt to mask facility smells, technology is available today that molecularly neutralizes offensive odors, and with the right partners, facilities can find solutions tailored to their needs.
Varied constituents create complexity
While offensive odors are a problem for most grow facilities, the exact odors vary based on the plant strains in each grow room. Cannabis odor is a complex mixture of chemicals, and the characteristic scent typically comes from the terpenoids and terpenes it contains. While on their own, some of the constituent aromas can be pleasant, the odor produced when these scents are combined is pungent and objectionable — attune to mixing vibrant paint colors, resulting in a muddy mess.
Terpenoids can be further classified into monoterpenoids, sesquiterpenoids, diterpenoids and triterpenoids — each of which are acyclic, monocyclic or polycyclic hydrocarbons — with all contributing to the smell. Because these scents and their chemistry vary, there is no single odor solution that works for every application.
As the cannabis industry expands, many municipalities are imposing restrictions on the methods employed by commercial growers to handle odors. Particularly in urban areas, large-scale ventilation systems that pump untreated air outdoors are widely prohibited. Some facilities use industrial filtration systems, but these are costly to install, operate and maintain. Sealing a greenhouse is an alternative option, but this can cause overheating, along with harmful humidity increases.
There are several odor control methodologies used throughout the cannabis and other process industries, but traditional solutions each have shortcomings in various forms. These methods include masking agents, chemical scrubbers, adsorption and carbon filters, ozone, biological filters and others (Figure 1).
While ozone — a powerful oxidant and anti-microbial — can be used to effectively remove odors from greenhouses, it causes side effects when used around humans, requiring facility evacuation during and after use. This is disruptive to operations and requires an excessive level of scheduling and planning. Additionally, ozone is highly caustic, so it can cause damage to equipment when in the presence of other chemicals.
Most cannabis greenhouses use carbon filters to remove odors emitted from the facility. These filters work by pushing a contaminated air stream through activated carbon. Carbon is porous, providing it with a large surface area, enabling absorption of the odorous chemicals. Activated carbon filters work well on sulfur-rich compounds, but they are not as effective at treating nitrogen-based compounds. They also require annual or more frequent replacement, resulting in high ongoing maintenance costs. Carbon filters also restrict airflow through greenhouse fans, and because airflow is vital to growing, additional fans are often required.
Other traditional odor control methodologies require equipment, materials, setup and maintenance from multiple partners, and these complexities can render systems unwieldy and costly to operate. Fortunately, modern plant-based formulations can safely and effectively mitigate odors in and around cannabis grow facilities.
Science-based solutions
Because of the various molecular makeups of cannabis odors, based on contained terpenes and concentrations of sulfurous compounds, plant-based odor neutralizers are available in multiple different formulations to counteract a range of smells.
To determine the best formulation for each facility type, scientists begin by taking gaseous samples using Markes-thermal desorption tubes. The analytes in the air grab onto these sorbent-lined tubes, keeping the samples intact and accurate for several weeks — vastly longer than the 24-hour shelf life of samples captured in Tedlar bags. Detection limits are also much lower with samples captured in this manner, meaning fewer samples and smaller volumes are required for high-quality analysis.
After samples are taken, they are run through a gas chromatography mass spectrometer (GC-MS) to determine the precise molecular makeup, even those present in minute amounts (Figure 2).
Each compound detected appears as a single peak on the graph, with the corresponding retention time value used for identification. Once the odor-causing compounds are identified, Ecosorb scientists can determine the most effective plant-based oils to molecularly neutralize the odors.
This results in versatile and cost-efficient solutions — specially crafted for maximum effectiveness — with each leveraging scientifically founded concentrations of biobased oils to eliminate odors. This includes those caused by cannabis, cannabinoids, terpenes, sesquiterpenes and sulfur-containing compounds.
Atomization systems
Odor abatement formulations are primarily delivered to affected areas via atomization or vaporization techniques. With atomization, concentrated odor eliminators are mixed with water and pumped through pipes, then droplets are sprayed into the air, neutralizing odor molecules on contact (Figure 3).
Atomization nozzle systems provide a significant level of control, with the ability to vary product volume, surface area and spray method. These conditions can be controlled with hydraulic high-pressure or pneumatic low-pressure systems. High-pressure systems treat odors by dispersing a fine mist into the air to treat escaping gas emissions and surface odors, while low-pressure fan systems are effective in confined spaces and environments for containing multiple odors released in a small area.
Portable, low-pressure fan systems spray a mixture of odor eliminator and water through a fan’s jet stream, creating a fine mist throughout the area. Because atomization delivery systems are generally compact, they are flexible and customizable, and easily transitioned from one process area to another. Additionally, the use of concentrated odor eliminators reduces shipping costs and storage space requirements because water, which makes up most of the bulk and weight, is added at the site.
Vaporization systems
Many cannabis facilities use vaporization delivery for odor mitigation around building perimeters. Unlike atomization, no additional water is required in vaporization systems, as this delivery method pumps specially blended odor eliminating emulsions through perforated pipe distribution systems, dispersing a dry vapor to eliminate airborne odors. Vaporization uses less water compared to atomization, providing cost savings and a more eco-friendly delivery method (Figure 4).
Vapor phase systems deliver dry odor eliminator at rates as low as 50 cubic feet per minute (CFM) to as high as 2,400 CFM, making them adaptable to many locations and applications. These flexible and efficient delivery systems:
- Provide smaller droplets and higher absorption for better odor control.
- Require no additional water to operate.
- Eliminate the need for mixing and diluting.
- Reduce maintenance requirements because no nozzles are required.
Cloud tools for remote monitoring
- To increase ease of use, Ecosorb atomization and vaporization units can be managed remotely through secure cloud connections. This interface, called EcoLink, empowers industrial users to:
- Remotely start, stop and change system operating mode.
- Identify low product levels.
- Track and trend flow rates, energy use, downtime and other key performance indicators.
- Send alerts and notifications.
- Adjust product dosage to coincide with fluctuating odor-producing periods.
- Encrypt data for transit and storage.
- View metrics, charts and diagrams on an intuitive dashboard.
These remote capabilities provide the means to run odor abatement equipment more efficiently by varying formulation concentration and dispersion in real time from anywhere in the world, aligning with changes in external operating factors.
Results: Effective odor mitigation for cannabis cultivation
In the spirit of being a good neighbor, a large U.S. Midwest cannabis cultivation facility attempted to alleviate odorous emissions into surrounding neighborhoods by treating exhaust air with masking agents. That did not work, however, as complaints began mounting just months into the facility’s opening. To address the problem, the facility engaged Ecosorb to sample the air and prescribe a better solution.
Analysis determined Ecosorb’s plant-based CNB100 formulation as the most effective molecular neutralizer for the facility’s emitted odors, where it was diluted at a ratio of 300:1, and then atomized through a high-pressure system (Figure 5).
The natural ingredient composition provides a safe, effective and environmentally-friendly means of odor control, with minimal required maintenance. Proving success, complaints from the neighborhood no longer accrue.
Driving business continuity
Plant-based odor neutralizers help keep cannabis cultivation and other facilities in the good graces of neighbors and within regulatory compliance so production can continue uninterrupted. While many facilities attempt to address foul odors using masking agents, they are not as effective or sustainable because these agents simply cover unpleasant smells with synthetic fragrances or harsh chemicals.
Proper odor management instead requires neutralizing the offending components by altering the air’s molecular makeup to provide safe, environmentally friendly, cost-efficient and effective odor control solutions. Plant-based custom formulations give cannabis growers and many other industrial processors the means to operate efficiently without sacrificing their reputations for clean and environmentally conscious practices, while improving neighbor relationships, advancing public opinion and increasing profits.
Glenn B. Crisler II, Ph. D., is the senior research and development scientist for Ecosorb, where he manages the research and development laboratory. Dr. Crisler graduated from Mississippi State University with a B.S. in chemistry before earning his Ph. D. in analytical chemistry for his work using renewable green sorbents to mitigate heavy-metal and fertilizer contamination in municipal and agricultural wastewater. As a leading member of Ecosorb’s R&D team, Dr. Crisler uses his analytical skills to develop and validate research methods that improve efficiency and reproducibility, while deepening Ecosorb’s understanding of complex, multidimensional odors to better tackle ever-evolving mitigation challenges.
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