Off-Gassing: Combustible Gases and Cannabis Waste Management
Cannabis waste generated through different extraction methods carries different risks, particularly when it comes to off-gassing. Waste from solventless processes can produce methane, a naturally occurring flammable gas released when organic material decomposes in oxygen-deprived (anaerobic) conditions. By contrast, waste from solvent-based extraction retains residual chemical vapors such as butane, propane, or ethanol, which can accumulate and pose flammability risks if not properly off-gassed.
Solventless Extraction Waste: Cleaner, But Still Needs Careful Storage
The extraction method used determines how the leftover biomass should be handled.
Solventless extraction methods like ice water extraction and heat-press techniques isolate cannabinoids without the use of chemical solvents. What’s left behind is chemically unaltered biomass—plant material that still contains natural sugars, lipids, and other organic compounds.
This waste is considered cleaner, but can still pose risks if not properly managed. When sealed, deprived of oxygen, and in a moist environment, the biomass can undergo anaerobic decomposition, generating methane gas. As such, proper storage and disposal are essential.
This waste is compostable when managed properly.
Biomass Conditions That Create Methane
The likelihood of methane generation depends on the extraction method and how the biomass is stored.
Fresh, frozen waste is more susceptible because it retains moisture and, when sealed away from oxygen, can support anaerobic decomposition.
Dried waste, by contrast, has low moisture content and limited microbial activity, making methane production highly unlikely under any storage conditions.
Methane production is less likely in open-air or exposed conditions.
Solvent-Based Extraction: Off-Gassing Risks After Processing
Solvent-based methods use volatile hydrocarbons like butane, propane, or ethanol to isolate essential oils, cannabinoids, and terpenes from plant material. These processes leave behind biomass that has been chemically stripped of many organic compounds.
Vapors from solvents still linger in the biomass, creating hazards. Proper off-gassing is necessary to release built-up vapors before transport or disposal. Adequate drying, ventilation, time, and adherence to environmental regulations are key.
Butane off-gasses over time typically without any microbial action.
Time Is a Core Consideration for Solvent-Based Waste
The leftover material after solvent-based extraction will hold flammable vapors that need to be released before disposal.
Solvent vapors are heavier than air and tend to settle at the bottom of containers. Even if stored in an open-top container, vapors can remain concentrated below—a dynamic known as stratification. Once the container is sealed, it's difficult to fully off-gas unless it was pre-staged properly. Storing extracted biomass in containers that allow gas to vent from the bottom is essential.
Waiting for the proper amount of time is also important. Even in a compliant, vented C1D1 room, off-gassing takes several full days.
Composting Cannabis Waste With Monarch Waste Co.
Green and solventless extraction waste, as well as properly off-gassed solvent waste, can be diverted to compost. Monarch Waste Co. helps cannabis operators determine compost eligibility and provides tailored strategies for managing all types of cannabis waste, aligning regulations set forth by the Environmental Protection Agency (EPA) and the Missouri Department of Natural Resources (MO DNR).
Services include:
On-site combustible gas metering
On-site waste storage and staging assessment
On-site observations to assess waste stream handling practices
How Monarch Monitors Waste for Flammable Gases
Our team routinely monitors extracted cannabis waste for flammable gases using LEL (Lower Explosive Limit) meters. While methane is a common concern, the vapors we detect are most often residual butane, propane, or ethanol.
Rising LEL readings over time are typically caused by residual butane slowly releasing from wet or compacted waste. Moisture can trap butane within layers of biomass, and temperature changes or microbial activity could cause it to off-gas gradually.
Any elevated readings are addressed on-site to maintain safety and compliance.
Schedule Your Waste Stream Assessment
Proper cannabis waste management requires a comprehensive understanding of your facility's specific needs. Monarch Waste Co. initiates this process with a thorough assessment.
Our team will evaluate your waste stream and develop a customized management plan. From there, we’ll deliver secure containers to your facility, schedule pickups around your workflow, render the waste on-site so it meets compliance requirements before leaving your property, and more.
Learn more by contacting us today and scheduling your assessment!