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Addressing Quaternary Ammonia in Wastewater Treatment System Designs

Posted on by Allison Blodig, REHS

Question of the Week: What can we do on the design side to address the use of quaternary ammonia?

What is quaternary ammonia? Quaternary ammonia compounds, or “quats” are classified as pesticides by the EPA and are a common ingredient in sanitizing products used in commercial facilities and in homes. In commercial food preparation facilities, they are used in their 3-vat sink washing procedures as the final sanitizer. In both commercial facilities and homes this ingredient can be found in bathroom and toilet bowl cleaners, liquid fabric softeners, laundry sanitizers, and some anti-bacterial hand soaps. Quats are not volatile compounds like chlorine that get bound up quickly in a septic environment. They keep killing bacteria for a long time. 

So, how can wastewater treatment systems be designed to address facility use of quaternary ammonia? Unfortunately, there is no way to design a part of the system to lessen the effect of quaternary ammonia sanitizers. If the owners are using these products in a lot of applications and will not change their product use or the amount they are using, then the system will struggle to treat wastewater, especially if the system needs to reduce nitrogen.

It comes down to educating the property owner and changing habits. I have had success getting restaurants and homeowners to switch away from quats if they need nitrogen removal. It simply will not perform well if they do not stop the use of these products and their permits can be violated.

If the system is a conventional septic and/or they do not need nitrogen removal, owners can slow down on the use of quats. For instance, if a restaurant facility insists on staying with quats, they should only change their 3-vat sink water if it is below 75 degrees or when it has lost its effectiveness (evaluated by utilizing test strips required by the food code), NOT every time they change their dishwashing water. In a home, stopping the use of laundry sanitizers or liquid fabric softeners will likely be the place to make an impact. If owners are not overusing quat sanitizers, then the system should be able to function assuming all other things are designed properly to meet the influent loading on the drainfield or the aerobic treatment system.

About the Author

Allison Blodig, REHS
Wastewater Treatment Systems Specialist 

Allison has been in the onsite wastewater treatment industry since 1997, first as a regulatory official and then in the wastewater treatment manufacturing industry participating in sales, regulatory affairs, design reviews, and training for a national treatment system manufacturer. Ms. Blodig had her own company for 3 years called GYST (Get Your “Stuff” Together) Consulting, specializing in regulatory consulting, market research, and training across the US. Currently she is an Engineered Systems Specialist with Infiltrator Water Technologies, a leading developer of decentralized wastewater treatment technology. Along with a degree in Biology from Benedictine College in Atchison, KS, she has been a Registered Environmental Health Specialist and member of the National Environmental Health Association since She is also very active with the National Onsite Wastewater Recycling Association (NOWRA) and is the former chair of the Technical Practices Committee, current chair of the Conference Committee and participates in the Online Education Committee. She has participated in the NSF Joint Committee on wastewater, participating in task groups and annual meetings. Allison received the Women in Manufacturing award in 2012 and was the 2017 recipient of the Raymond Peat Lifetime Achievement award for outstanding achievement in the Kansas onsite wastewater field.


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