Safer Disinfection With Peracetic Acid

Source: SOLVAir Solutions

John Maziuk, Technical Development Manager at Solvay Chemicals, discusses the benefits of peracetic acid over other wastewater and stormwater disinfection methods, including no harmful byproducts, a simpler process, and a longer shelf life.

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The following is an excerpt from a Q&A with Water Online Radio. Click on the Radio Player above to hear the full interview.

Water Online Radio: Tell us a little bit about yourself and Solvay Chemicals.

John: I am a chemical engineer with Solvay Chemicals at their North American headquarters. Solvay is an international company, and we make many different types of chemicals with regard to peracetic acid. Peracetic acid is a combination of acetic acid and hydrogen peroxide, and that’s a good part of why we’re also one of the largest producers of hydrogen peroxide as a major raw material.

Water Online Radio: What is new and different with regard to peracetic acid and how it is being applied?

John: Probably the newest thing about peracetic acid is increased awareness. Years ago, people used to just want to find out what it was. Now, customers call to ask whether they can use it in their application.

Water Online Radio: I suspect they are asking the same question I am about to ask. What advantages does peracetic acid have over other disinfectants?

John: Peracetic acid is an organic acid. It’s a clear liquid that has a very similar viscosity and density to water. It has to be handled carefully, but the nice thing is that the byproducts of it are acetic acid and hydrogen peroxide, which are not harmful at all.

Water Online Radio: Talk about the process of using peracetic acid effectively.

John: Because it’s a liquid, in most cases, you can actually use peracetic acid much like sodium hypochlorite. It’s stored in the tank, pumped into some type of mixture or dispersion device, and it’s corrosive just like sodium hypochlorite. We know what materials and composition to use, and if it is stored properly, the stability of peracetic acid is over a year under most conditions. Unlike bleach, it has an extremely low freezing point.

Water Online Radio: Have there been trials at municipal water plants?

John: Yes. Recently, we have had several trials in parts of the central US, and these particular plants were using sodium hypochlorite with a dechlor step. The issue with that is that the chlorine byproducts aren’t good. With peracetic acid, you don’t have that issue. It also means that you only have one step rather than two steps because you don’t have to worry about both the chlorination step and the dechlor step. These trial plants have now switched to peracetic acid (PAA).

We have several other ongoing trials and we expect to have a couple of more plants online within the next four or five months.

Water Online Radio: What kind of cost impact do you expect coming out of that?

John: For people that are using a bleach process, it really is not a major cost differential. When you compare it to other processes for disinfection like UV, which is extremely capital intensive, it actually is quite economical. It is certainly cost competitive with any of the disinfection processes.

Water Online Radio: I understand you are doing some work with the EPA. Tell us more about that.

John: Solvay Chemicals has a Cooperative Research and Development agreement with the US EPA as a corporate sponsor of a side-by-side study that will be comparing sodium hypochlorite performance with PAA performance. We have a facility in Cincinnati that we will be using to create a model of a wastewater treatment plant, and we will be analyzing both processes under basically the same operating conditions.

There are a couple of equipment process controls people that are interested in what we are doing and we’re going to be using some of their equipment to see how it handles the PAA solutions. We are looking forward to presenting that work next year. This is something I really enjoy doing.

Water Online Radio: What about other applications? Can PAA be used for stormwater as well?

John: It is excellent as a disinfectant for stormwater. Because it disperses so rapidly, it’s highly soluble in the water. Also, in many areas, it may not rain too much for a few of weeks. This is where PAA’s long shelf life provides an advantage over chlorine...

Click on the Radio Player above to hear the full interview.