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Cannabis Waste Management: What Do Companies Need to Know?

By Leo Bear-McGuinness

Published: Apr 15, 2020   
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Given the notorious avidity of marijuana enthusiasts, it’s a wonder the cannabis industry has any waste to speak of. Even if a dispensary has a quiet day, the staff discounts should help disappear any products at the end of their shelf life, right? But marijuana’s biggest waste issues aren’t found on the retail side. The sector’s main environmental pitfalls come much earlier in the supply chain, back in the agricultural and extraction phases. And they’re a growing problem.

Unused plant matter and cultivation trimmings. Discarded extraction chemicals. Trashed testing samples. This is the debris the cannabis industry leaves behind. And if not properly disposed of, these chemical residues could pose serious environmental risks to nearby surroundings.

So, to keep the “green” in the green industry, what should environmentally-conscious cannabis companies be aware of?

An inconvenient shoot

“Well, let's start with the Clean Water Act,” says Dr Edward Askew, founder of Askew Scientific Consulting, an Iowan analytical chemistry firm that has helped several cannabis companies comply with waste management laws.

Established in 1972, the Clean Water Act made it unlawful for any company or individual to discharge pollutants into navigable waters unless a permit was obtained. And good luck getting a permit if you’re a cannabis extraction company...

“Let's say you’re running an [cannabis] extraction plant,” Askew tells Analytical Cannabis. “So I've distilled off the ethanol, and I have my extracted oil or waxes. Now I've got all this waste ethanol. What do I do with it? Well, you can’t discharge it down the sewer.”

So, quite rightly, the riverbed’s a no-go. 'But what about the incinerator?' some crafty cannabis extractor asks. Don’t count on it, says Askew.

“You can try to reclaim the ethanol, but you're still left over with this tar-like material that you have to get rid of,” he says. “And you just can't burn it unless you have an incinerator ruling for your boilers. And the problem with that is you may violate air quality rules on your discharge from your stacks.”

Well, the chemical waste might be a nuisance, but surely the left-over plant matter is easy to dispose of, right? Think again, says Askew.

“Let's say I'm extracting the [cannabis] stalk. I have all of this fibrous material leftover. What do I do with it?” Askew asks. “I've run into places where they'll say, ‘Oh, we'll just compost it.’ Well, the problem is you’ve got to get rid of the compost after you're done. So you say, ‘Oh, we'll take it to the landfill.’ Well a lot of states, because they're running out of landfill spaces, actually have regulations prohibiting you taking large bulk agricultural product to the landfill.”

OK, so the authorized landfill’s no longer an option. Where else can cannabis be disposed of, then? Well, for some time-strapped companies, the dumpster out the back of the building can start to look like an efficient option. But beware the temptation, says Askew, because cannabis is no ordinary trash.

“There's one thing other industries don't have to worry about,” Askew says, “and that's the DEA looking at their waste disposal.”

Because THC and other cannabinoids are still considered federally illegal in the US, the Drug Enforcement Administration (DEA) can hand out hefty penalties to any company that doesn’t keep their cannabis under lock and key. But that hasn’t stopped some businesses from taking the risk.

“In some places, like California, the bulk waste has to be locked up because [it] is still considered marijuana,” says Askew. “One laboratory I went to, their control was a big dumpster out back. The state hadn't caught them yet. But your waste [is] still going to be viewed as something that can produce THC.”

The solution to pollution

When first presented with all these restrictions and requirements, a cannabis company might feel like it’s chained to its waste. But with a little guidance from a qualified disposal company, any company can still find plenty of ways to responsibly refuse.

The first step? Dilute your marijuana. Yes, it might seem like a wasteful step in and of itself, but the Environmental Protection Agency (EPA) requires all companies to first render their cannabis waste “unusable and unrecognizable” before disposal. Practically, this involves grinding up and mixing the waste with non-consumable solid scraps, such as carboard or food waste.

Once this unpalatable mess has been created, it’s time to get wasting. And if composting cannabis plant matter, it’s important to use a compost facility approved by state officials. No such facility nearby? Well, there might be another option.

“There are other places you might be able to take that material and feed it into an organic digester at the wastewater plant,” says Askew, “especially if the wastewater plant is making methane gas for reuse. The methane gas is going to be collected and used as a fuel for city vehicles. So you do have some options there, but you have to work with the wastewater industry.”

Some types of waste won’t be allowed near such facilities, though. If contaminated with pesticides or any other chemical that could be deemed “hazardous,” some waste will need to be treated under the EPA’s Resource Conservation and Recovery Act (RCRA) guidelines. And this type of waste isn’t easy to get rid of.

“God forbid you produce RCRA waste, [because] you are in a lot of trouble,” Askew warns. “Because unless you want to pay a lot of money, I mean, I'm talking about extremely high amounts of money to get rid of that, you're not going to.”

Unfortunately, as an agricultural crop, cannabis waste is highly prone to pesticide contamination. And when they’ve reached a certain amount, these pesticide residues turn the marijuana debris from general waste into RCRA waste. So, if in possession of such highly hazardous litter, what can a company do?

“Once you produce that waste and it's sitting in a tank on your site, you're in a lot of trouble, because you can't get rid of it legally without sending it to a RCRA waste facility,” says Askew.

As these specialist facilities are unevenly spread across the US, it can cost a company a small fortune to ship their waste depending on its location.

“So here we are in Iowa,” Askew continues, “and the closest place they can take this waste is a RCRA facility in New Jersey. So, they have a fleet of tanker trucks going to and from this facility [across] about 1500 miles… And [that] may eat up all of your profit for the year to get rid of 500 gallons of waste.”

It may be costly, but as RCRA waste can pose real threats to surrounding environments, these expenses are a necessary part of responsible cannabis production. And as the US cannabis industry grows, these facilities will hopefully become more accessible.

This article originally appeared in Analytical Cannabis' Advances in Cannabis Extraction and Processing ebook in March 2020. 

Leo Bear-McGuinness

Science Writer & Editor

Leo joined Analytical Cannabis in 2019. From research to regulations and analysis to agriculture, his writing covers all the need-to-know news for the cannabis industry. He holds a Bachelor's in Biology from Newcastle University and a Master's in Science Communication from the University of Edinburgh.


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