Phasing out the use of microbeads is great news for septic systems
Microbeads became a national issue a few years ago. Microbeads or microplastics are particles less than 5 mm in their longest dimension and are often smaller, down to 0.335 mm. They are currently common in many beauty and cleaning products. There are over 100 products sold in the U.S. containing mircobeads, including toothpaste, sunscreen, shampoo, soap, lip gloss and moisturizers. Microbeads are typically manufactured using polyethylene. Polyethylene is known for its reluctance to biodegrade and its ability to absorb persistent organic pollutants which also do not degrade.
On Dec. 28, 2015, President Obama signed a bipartisan bill that prohibits selling and distributing products containing microbeads. The bill is intended to protect the nation's waterways.
What’s the problem?
The problem with the beads is they are made of nonbiodegradable plastic. Most of the microbeads used in personal care products are fragments, not easily identifiable spheres or speckled pieces. In fact, spherical or speckled microbeads averaged less than 6 percent of the microbeads found in 16 different personal care products examined, according to data from the State University of New York at Fredonia. In September, a study published in Environmental Science & Technology reported that more than 8 trillion microbeads were entering the country's aquatic habitats daily. The volume was enough to coat the surface of 300 tennis courts every day.
Microbeads are not removed by wastewater treatment plants or septic tanks because, unlike organic sewage, they neither bind together and settle in the effluent nor are they eliminated through biological processes. The plastics in current microbeads are buoyant, which increases their chance of floating right through. Due to their size, they will easily pass through effluent screens and therefore end up in the discharge to the soil treatment area. The microbes in the soil are not able to break down these plastics either, so they will likely accumulate in the soil or could cause plugging of the soil pores.
This ban is good for all the water systems in the U.S. and our septic systems, although it will take a few years for them to be phased out. Unfortunately, much of the plastic in the environment is not from microbeads, but from the breakdown of larger plastic material. The amount of plastic debris in our waters will continue to be an issue. A report in 2015 estimated 8 million tons of plastic, including large and small particles, are dumped into the ocean and accumulate in “garbage patches.”
About the Author
Sara Heger, Ph.D., is an engineer, researcher and instructor in the Onsite Sewage Treatment Program in the Water Resources Center at the University of Minnesota. She presents at many local and national training events regarding the design, installation and management of septic systems and related research. Heger is education chair of the Minnesota Onsite Wastewater Association (MOWA) and the National Onsite Wastewater Recycling Association (NOWRA), and serves on the NSF International Committee on Wastewater Treatment Systems. Send her questions about septic system maintenance and operation by email to firstname.lastname@example.org.