Wastewater Treatment Plants and Marine Debris

Posted Tue, 04/25/2017 - 11:00

By: Matthew Coomer, Intern with the NOAA Marine Debris Program

You may not think about wastewater treatment plants (WWTPs) very often, but you use them every day. In fact, they are essential to protecting our health and the environment; WWTPs change our sewage into clean water that can safely re-enter rivers and the ocean. These facilities are complex, but to simplify, they filter solid material out of wastewater, allow microorganisms to feed on the organic matter that’s left behind, and then kill any dangerous bacteria. Whenever you use water at home or in your community, you use your local WWTP. Unfortunately, while these treatment plants are very good at their job, they may also be point sources of a persistent type of marine debris— microplastics.

When most WWTPs were designed, most people weren’t thinking about potential environmental impacts from plastic or how popular it would become. In many ways, treatment plants still handle plastic debris really well. When large pieces of plastic (like food wrappers) enter the system, they are separated for proper disposal like other solids. Studies show that modern plants capture over 99% of microplastics, too. Sadly, even that remaining 1% is a big problem. WWTPs work through millions of liters of wastewater every day, so a few plastic particles per liter can add up to billions released over time. Unfortunately, creating new filters and upgrading old systems to capture all these particles can be very complicated. Instead, we can all work to prevent plastics from going to WWTPs in the first place.

Plastic microbeads are added to many personal care items like soaps, toothpastes, and body washes. These beads act as an exfoliant and are designed to wash down the drain. “Out of sight, out of mind” only flows as far as the treatment plant, though. Several studies have found that most microplastics entering WWTPs are from consumer products, so reducing our use at home matters. Thankfully, Congress gave us a hand when it passed the Microbead-Free Waters Act of 2015, which will stop the production of microbead-containing rinse-off cosmetics this July and ban their sale next year. Until then, look to see if that scrubbing product in your bathroom contains plastic microbeads and, if so, use a different one next time. When everyone makes this small change, it could have a huge, positive impact. Your WWTP will appreciate the help in keeping our waters clean, healthy, and debris free.