Five Tips for Designing a Cannabis Wastewater Treatment System

Posted on 7/31/2020 by Brenda Faz

In the United States 11 states have completely legalized the use of cannabis for both medicinal and recreational use. Several other states have a mixed legalization status, based on medical use only and decriminalization. Marijuana is still fully illegal in only eight states. Cannabis is a multibillion-dollar industry and some studies project more than triple revenue growth over the next several years.

Wastewater solutions for cannabis facilities vary depending on the state or local authority and currently, there is no specific regulation surrounding onsite wastewater treatment systems and the allowance of cannabis process wastewater. Some facilities are recycling wastewater for a zero discharge, while other industrial scale facilities are employing collect, store, haul strategies like agricultural and pharmaceutical hazardous waste practices. Some local municipalities are requiring any cannabis-related facility to characterize their waste before they allow that location to release wastewater into their treatment plant.

Wastewater areas of concern and focus vary by the type of cannabis facility. In my dealings and experience with cannabis facilities, I have narrowed this down to three categories, for ease of explanation and design practices: Growers, processors, and end-product manufacturers. While it may not be practical to continuously characterize waste at each facility, there are some key practices associated with each of these categories that a regulator, operator or designer can keep in mind when determining best practices for wastewater management:

Growers may be using conventional insecticides and fertilizers and this usage will vary based on indoor vs. outdoor grow facilities. Understanding what products and in what quantities as well as their application and water usage practices will help determine waste characterization. Others are using organics practices; therefore, their impact will not be as great. All will have spent plant material that will be part of the waste challenge.
Processors will also have spent organic material, but they will also have waste oils, terpenes, and solvents that will potentially require a greater level of treatment prior to disposal. It is key to understand what extraction methods these processors are using, how often they are running these procedures, and how much waste is being generated on what type of timeline.
End-product manufacturers’ wastewater streams may include oils, surfactants, industrial cleaners, waxes, and edibles, food processing by-products all of which present their own set of potential challenges.

If you’re tasked with designing a wastewater treatment system for a cannabis facility, here are the five key questions to address:

1. What type of facility are you designing for?

1. Grower
2. Processor
3. End-Product Manufacturer
4. Combo of these
5. Medical or Recreational
6. Indoor or Outdoor

2. What processes will they be using specific to chemical use and residue?

3. What will the wastewater consist of?

1. Process
2. Runoff
3. Domestic

4. What are the wastewater parameters?

1. Average Daily Flow
2. Influent expectations
3. Effluent requirements
4. Site constraints or characteristics
5. Water usage
6. Recycling practices

5. What local regulations and design criteria exist?

Although we can develop treatment system design and waste disposal criteria based on the above-mentioned guidelines, there is still insufficient data available on cannabis wastewater characterization to develop efficient systems and procedures. That data is key to developing policy and procedure best practices for cannabis wastewater collection and treatment. Another challenge is that state and federal law is not aligned when it comes to marijuana legalization, hampering broad best practice development that can be implemented across the US. Most other commodities or crops have federal framework that allows for state implementation, with some adjustment, if needed, that strives to focus on adjustment towards local conditions. However, given the conflict between federal and state legalization for this specific industry, that framework does not exist, leaving it open for every situation to have a procedure of its own. This can be a regulatory nightmare. It is important that the wastewater industry come together and share research and knowledge as this becomes a norm in business, so we can help frame the regulatory policy that will serve in the best interest of the manufacturers, regulators, consumers, and overall environmental health.

About the Author:

Brenda Faz
Engineered Systems Specialist

Brenda Faz is the Engineered Systems Specialist for the Southern Region of the United States at Infiltrator Water Technologies. Brenda assists developers and engineers in

designing wastewater treatment systems that will optimize treatment performance for their projects. Prior to working for Infiltrator, Brenda spent 15 years in the environmental testing industry, doing bench scale treatability studies for municipal wastewater plants as well as standard analytical testing for soils and waters under both Standard Methods and ASTM methodologies. Brenda holds a Bachelor’s Degree in Environmental Science from Texas A&M University, a Master’s Degree in Environmental Management from the University of Maryland University College, and is currently a PhD student at Louisiana State University in the Environmental Science program.