Ozone is beginning to play a larger role in the cultivation and production of cannabis, which is a large and growing industry. Grandview Research estimates that in 2020 the global cannabis market was worth $9.1 billion with a projected CAGR of 27% from 2021 to 2028.
While a growing number of US states have legalized cannabis, 18 at latest count, virtually all have some form of legal cannabis such as medical cannabis or have decriminalized it use.
The nature of these cannabis laws varies widely state to state, but cannabis use will increase in the US. In California, for example, cannabis is projected to be the top agricultural product in terms of value ahead of milk and cheese.
The Role and Application of Ozone in Cannabis Production
Ozone is finding an expanding role in cannabis cultivation, production and processing. The federal regulatory framework for cannabis is not in place at this time and there is a patch work of state laws governing the various aspects of cannabis production including areas where ozone can be used. Eventually, like all consumables, cannabis will be required to meet GMP, or good manufacturing practice, like other food processing and pharmaceutical products.
Some applications for ozone in cannabis production include:
- Cannabis Irrigation Water Treatment
- Cannabis Wastewater Treatment
- Cannabis Air Emissions Treatment (Gas Phase)
- Finished Product Disinfection (Gas Phase)
Ozone In Fertigation Water
The main application for ozone appears to be treating the water to grow the plants. Cannabis can be grown with or without soil using water with nutrients added. This nutrient rich water can be a breeding ground for plant pathogens and biofilm formation.
Greenhouse Biofilm Formation Prevention
A biofilm is a layered aggregate or micro-colonies of predominantly bacterial cells (both primary and opportunistic), living in a protective hydrated glycocalyx matrix of extracellular polymeric substances! (EPS) of DNA, nucleic acids, and polysaccharides.
Greenhouse and nursery operations are particularly susceptible to biofilm problems. Biofilm establishes itself and thrives most easily in a nutrient rich environment, with warm temperature that are conducive to bacterial growth, and with a large surface area to water volume ratio. This of course describes the typical greenhouse or nursery operation’s irrigation system.
Ozone can be added to this water to prevent biofilm formation, remove plant pathogens and add dissolved oxygen to the water. Dissolved oxygen has been found to help plants grow.
Depending on the nutrient mix, it may not be best practice to add ozone to the fertigation water. Fe nutrients, for example, can be adversely affected by ozone. One approach here is to add ozone to the RO water reservoir and then remove the ozone prior to addition of nutrients. Periodically a sanitation cycle can be employed to remove biofilms.
Cannabis Growing Water Irrigation System with Ozone
Commercial cannabis growing and cultivation requires irrigation of some form and ozone can be used to remove various contaminants from water. Ozonated water is an optimal way to clean a hydroponic system because it saves time for disinfection. Additionally, industrial ozone generation can be used during a grow cycle to purify the water and avoid cannabis root rot.
Here is a general arrangement of a cannabis water irrigation system with ozone:
In recycling irrigation systems, this approach may not be an option. If ozone is added in these situations, impacted nutrients may need to be added in higher does to compensate for the loss of the nutrient. This has been done in vertical farming operations producing leafy green vegetables.
Cannabis Wastewater Treatment
The cannabis industry wastewater treatment standards have not been well defined but will probably follow the approaches taken in similar industries. As might be expected different types of cannabis facilities will have different wastewater challenges.
Growers will primarily have nutrients in their wastewater, probably with a high level of nitrogen compounds. These are usually not best treated with ozone. Those that operate outside may have insecticides also present. Ozone has been shown to work well against certain insecticides, so this might be an application of interest. Processors of cannabis will have oils and solvents in their wastewater. Ozone based advanced oxidation processes might make sense here.
Commercial Cannabis Odor Control
Commercial cannabis growing and processing can release terpenes which might be considered objectionable by the processing facilities’ neighbors due to their odor. Terpenes typically have the C=C bond in their structure. Terpenes readily react with ozone in the gas phase. While ozone might remove the odor associated with terpenes, they also produce other toxic daughter compounds. This has been observed with terpenes found in cleaning products.
Finished Product Disinfection
One ozone company claims that ozone can safely clean cannabis flower, hemp, and trim without compromising quality, flavor or effect.
Additional Reference: Challenges Surrounding Developing Cannabis-Wastewater Handling And Treatment Best Practices
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