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Waste Stream Management for Cannabis Operations

By Alexander Beadle

Published: Feb 28, 2022   
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Cannabis is an extremely popular product, there’s no denying it. So the idea of significant volumes of cannabis products going to waste might even seem laughable.

But the retail market is only one half of the equation. Getting cannabis from the fields and onto dispensary store shelves is a significant undertaking, and one that requires lots of processing and diligent quality testing. These cannabis operations also produce a notable amount of waste product, and operators must dispose of it accordingly. But what does that involve?

The diverse world of cannabis waste

The term cannabis waste might bring to mind the off-cuts of some cannabis plants that need to be dealt with. But in reality, the pool of items that can be classified as being cannabis waste is extremely broad.

“If you’re in the cultivation facility it means one thing, if you’re in the production lab or production facility it means something else. In the testing laboratory, it has yet another meeting. In all of those places waste is defined, and sometimes it’s defined for them by the regulatory body,” Dr Susan Audino told Analytical Cannabis. Audino is a chemistry laboratory consultant at SA Audino & Associates, LLC, and a scientific advisor to AOAC International’s Cannabis Analytical Science Program (CASP).

“In general, in the laboratory, cannabis waste is the leftover product that a client drops off for testing. They drop off this much, but the lab only uses that much, that means we have an amount that becomes raw product waste,” Audino explained.

“Then there’s also the waste product – you mix up your cannabis in a bottle of something and now we have to get rid of that bottle that happens to contain some cannabis.”

Every different stage of cannabis production will have some kind of waste product, Audino explained. A cultivation facility might have plant material that has been contaminated by pesticides or mold that needs to be disposed of, and a dispensary might have products that have gone past their sell-by date. Hazardous cannabis waste usually refers to that which is contaminated with pesticides or residual solvents. In the case of retail waste, this could also mean items such as spent vape pens containing lithium-ion batteries.

Naturally, cannabis operators cannot dispose of their plant off-cuts in the same way that they would this hazardous waste. Improper disposal of cannabis waste could cause serious harm to the environment, but also to human and animal welfare – if products are not disposed of in a way that makes them undesirable and/or unusable, it heightens the odds of stray animals or “dumpster divers” coming across cannabis materials and unknowingly consuming them.

Waste disposal methods

Given cannabis’ status as a controlled substance under federal law, improperly disposed of waste material could bring an operator to the attention of the US Drug Enforcement Administration (DEA) and lead to hefty penalties. Other federal statutes such as the Clean Water Act also need to be considered when an operator is drawing up their disposal plan.

But federal prohibition also means that disposal procedures have largely been left up to the individual states to decide. Proper disposal techniques can therefore vary significantly between states, and operators should always check with their local regulatory body to confirm what is allowed.

The four most common disposal methods for cannabis waste are composting, landfill, incineration, or in-vessel digestion. All of these intend to render the cannabis waste as “unusable and unrecognizable,” thus limiting the risks that this waste might pose.

Compostable waste, such as plant waste, cannot be composted immediately. First, it must be mixed with at least 50 percent non-cannabis compostable waste, such as food waste, yard trimmings, manure, or wood chips. The same is true for non-compostable materials that are sent to landfill – these need to be mixed with other wastes such as cat litter, sawdust, or plastics.

“I believe that those scenarios were put in place to prohibit people from or dissuade people from going through the trash and pulling out unused flower,” Audino explained. “Who wants to go through kitty litter? Early on, many facilities were faced with people going through their trash.”

Incineration is another common method where the waste is sent to a licensed municipal solid or hazardous waste incinerator to be burned, depending on state regulations, or burned in a special incinerator on-site. The open burning of cannabis plants can cause other public health concerns, whereas disposal at a municipal facility means that the emissions from the waste can be more carefully controlled.

In-vessel digestion systems and facilities can also be used for the disposal of organic cannabis. Here, waste is decomposed using bacteria or other biological elements within a sealed vessel under aerobic or anaerobic conditions to render it unusable. Once the digestion process has run its course, the remaining material can normally be repurposed as compost or disposed of at landfill.

“Another [method] is to chemically degrade it,” Audino added. “It is getting recycled in an attempt to remediate or to create a different product. So if the material fails on some particular level, they say okay, we’ll just repurpose that and use it for something else where the specification isn’t this low and I have more opportunity to do more things with it.”

“From seed to destruction”

One of the biggest issues concerning cannabis waste stream management today is not so much a lack of regulation, but a lack of effective oversight.

“It is very, very difficult to monitor,” Audino said. “With seed to sale, you type in a lot number and you can track that down the food chain. With waste, there’s no way to track it […] so they are taking laboratories and cultivators and product managers and dispensaries at their word when they say, yes, we destroyed it.”

“Not everybody is going to lie,” Audino added. “But I know that the black market is thriving in response to this.”

This feeds back into the idea of needing to make cannabis waste unusable and unrecognizable, so that it cannot be salvaged by bad actors. But as things stand, it is difficult for operators to prove to regulators that they are in fact doing this transformation and disposing of their waste responsibly.

“​​I am aware of a new piece of equipment that has not yet hit the market, that should be hitting the market here very soon, but that provides an audit trail of exactly how much waste has been deposited into the machine with a date and timestamp, and then how it’s been destroyed by an external independent third party,” Audino said. “That can then prove that the cannabis waste has been destroyed.”

“It was developed to provide that audit trail of objective destruction that can then tie right back into the seed to sale. The goal with this is to extend the philosophy from seed to sale to seed to death, or seed to destruction.”

Until this equipment arrives and becomes commonplace, Audino believes that improved oversight should be a key focus for the nation’s regulators.

“It is a problem that, I hope, is on the priority list of CANNRA [the Cannabis Regulators Association],” said Audino. “I hope that they are looking at this as a problem and that they’re trying to solve that problem. Because if black market materials end up going into the wrong hands, people will get sick, and then it reflects badly on the legitimate industry.”

Alexander Beadle

Science Writer

Alexander Beadle has been working as a freelance science writer since 2017 and has covered the cannabis industry for Analytical Cannabis since 2018. He has also written for our sister publication, Technology Networks, and the cannabis industry consultant firm Prohibition Partners, among others. Alexander holds a Master's in Materials Chemistry from the University of St. Andrews, where he won a Chemistry Purdie scholarship, and conducted research into zeolite crystal growth mechanisms and the action of single-molecule transistors.


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