Dive Brief:

• Canada's move toward legalizing recreational marijuana presents a new waste stream to be effectively managed. According to Karen Lauriston, a spokesperson for Micron Waste, there will be an estimated 6,000 metric tons of cannabis waste in Canada by 2020.
• Micron is installing an aerobic digester on-site at Aurora Cannabis Inc., a medical marijuana producer and distributor. Micron President Alfred Wong told Waste Dive the digester should be operational by June this year.
• Micron testified before a Canadian Senate committee this week, Wong said. "We understood the committee had an interest in looking at compost and other ways to look at cannabis waste. We wanted to be there to say, 'we're here, we're being effective in what we're doing to manage cannabis waste.'"

Dive Insight:

Micron uses an aerobic process to avoid the generation of biomethane, Wong said. Cannabis waste is ground down to a particle size, and then broken down by bacteria, resulting in an effluent slurry and biosolid. The slurry goes through a 4-step process to clean it and remove compounds found in cannabis, such as THC, making it safe for agricultural use (or safe to just pour down a sewer).

The process is important, Wong says, because it saves on treatment costs. Cannabis waste can be landfilled or transported, but requires certain treatment standards for environmental health. Converting the cannabis waste to slurry and a biosolid is also faster than composting, a somewhat-common alternative for processing cannabis waste.

"There are on-site composting solutions," Wong said. "They work, but the issue is that it often takes a number of weeks for it to be fully processed. We like aerobic digestion is because it's quick." He added it takes a matter of days, instead of weeks.

Wong said he wants to "export" the company's product and technology "anywhere possible," and that work has including conversations with U.S. cannabis producers.

Already in Colorado, Republic Services treats cannabis waste as "special waste." Rich Thompson, senior manager of environmental compliance for Republic Services, previously told Waste Dive that cannabis waste is "[N]o different than any other new development in any of the places that we serve." Thompson said Republic was involved in helping the state develop regulatory rules, too.

As more jurisdictions in the U.S. legalize medical and recreational marijuana, companies and local governments will have to consider ways to properly handle disposal of the waste that comes with cultivation. While cannabis waste is organic and similar to agricultural waste, it has chemical compounds that can create a liability for those disposing it. Safe disposal requires mitigating those liabilities by removing those compounds like THC that are regulated in water supplies.