Q&A: PAHs and wastewater treatment

Q&A: PAHs and wastewater treatment

A new book in a series on advances in wastewater treatment examines polycyclic aromatic hydrocarbons (PAHs), harmful pollutants created when fossil fuels are burned. Recent studies have linked PAHs to cell mutations and cancer. Impeller recently spoke with Amy Forsgren, who edits the book series and is also a technical writer at Xylem.

Q: What are PAHs?

PAHs are multi-ringed organic compounds that are formed when you burn fossil fuels. They can come from energy plants, coal-burning power plants, car exhaust and even volcanoes. They are an environmental concern because they can cause mutations in animals. In 2014 in Canada, mutations in birds due to PAHs were reported for the first time. Unfortunately, this probably won’t be the last such report.

Q: Why are PAHs a concern for wastewater treatment plants?

PAHs are picked up by the rain and end up in storm water, which washes into sewers that lead to wastewater treatment plants. Wastewater treatment plants don’t generate PAHs, unless they burn sludge.

Treatment plants are often highly regulated in what they can release into the environment, including how much PAHs are released back into natural waters. So although the plants don’t generate the PAHs, they have a vital interest in tracking them. This includes measuring polycyclic aromatic hydrocarbons in the influent, tracking their fates through the treatment system, and making sure that their final effluent corresponds to regulations.

Q: How has our understanding of PAHs changed?

Historically PAHs haven’t been regulated at all. They’ve been an environmental problem that people haven’t realized the scope of until the past ten years. People are now aware, however, that rivers and especially harbors where storm water ends up can be extremely contaminated with PAHs. When a Canadian research group established a link between bird mutations and the amount of PAHs in Hamilton Harbor, it was a shock for the whole environmental community.

Q: What areas does the new book cover?

The book includes chapters written by research groups from around the world, including Poland, Italy, the US, Tunisia, Canada, Greece and Sweden. A couple of chapters look at the whole cycle of polycyclic aromatic hydrocarbons, how they enter the atmosphere and end up in the water, and how they affect fish and bird populations. Some chapters include reports on pilot test facilities for wastewater treatment plants where they have tried to optimize how PAHs can be removed. Other chapters look at which wastewater treatment sequences are the most efficient.

Q: Why is this book important?

It’s important because environmental legislation is becoming increasingly tighter, and the numbers of things we release back into the environment are coming under more scrutiny. Anyone who operates a treatment plant needs to be on top of these environmental issues.

The book is also important because this is a big issue for developing countries. Wealthier countries have advanced municipal wastewater treatment plants, which already have biological treatment. The bacteria in the biological treatment process love to eat polycyclic aromatic hydrocarbons, so at larger treatment plants this issue is taken care of. The problem arises when the wastewater is not biologically treated.

At smaller plants in the developing world, the biological stage can be too expensive to maintain so the sludge from the treatment plant is spread on fields for agriculture. Normally this would be good, but not if they are dumping PAHs in the soil. So we need to do a lot of work to try and find cheaper methods for smaller treatment plants.

Q: Who is this new book for?

It’s for engineers or owners of municipal wastewater treatment plants, people facing increasing legislation about PAHs who need some background information about what they are and how to get rid of them. It can also be interesting for legislators who are considering environmental legislation about polycyclic aromatic hydrocarbons.

Q: Why are you interested in this subject?

I’m interested in environmental issues, and this is my way of contributing. I work as a project coordinator and technical writer at Xylem, and I edit this book series in my free time. If anyone reading this article has any ideas for books they would like to see in this series, they are welcome to get in touch with me.
Read more about the new book here:

Previous books in this series can be found here:

by Simon