Microplastics are escaping from water treatment plants

Every time we wash our clothes, rinse our faces, or flush waste down the drain, we trust that water treatment systems will clean what we send their way. These infrastructures purify billions of gallons of wastewater globally.

But beneath this efficiency lies a troubling reality. Microplastics – fragments no larger than five millimeters in diameter – are evading the water filtration systems designed to keep our environment safe.

Emerging research from scientists at The University of Texas at Arlington reveals that despite the best efforts of wastewater treatment plants, these tiny plastic particles continue to leak into our soil, rivers, and oceans.

Their impact extends beyond the water itself, touching human health and disrupting ecological stability in ways we are only beginning to understand.

Plastics persist in wastewater systems

Plastics have become an indispensable part of modern life. Their affordability, durability, and versatility mean they are present in nearly everything – from food packaging and electronics to personal care products and textiles.

But their greatest strength is also their greatest danger. Plastics do not biodegrade; they break into smaller pieces, creating what we call microplastics.

“What our systematic literature review found is that while most wastewater treatment facilities significantly reduce microplastics loads, complete removal remains unattainable with current technologies,” said Un-Jung Kim, assistant professor of earth and environmental sciences at UT Arlington, and senior author of the study.

As these particles travel through wastewater, they often carry harmful chemicals like bisphenols, PFAS, and antibiotics.

“These microplastics and organic pollutants would exist in trace level, but we can get exposure through simple actions like drinking water, doing laundry or watering plants, leading to potential long-term serious human health impacts such as cardiovascular disease and cancer,” Kim added.

Key microplastics in water

The review, authored by Jenny Kim Nguyen and colleagues, investigated the specific types of microplastics that are dominating wastewater systems, namely microfibers and microbeads. These shapes, though often overlooked, form the core of plastic pollution in water.

Microfibers (MFs), the most common type found in wastewater, are released from synthetic fabrics like polyester, nylon, and acrylic. Laundry is their biggest release mechanism.

Once detached, these thread-like particles carry dyes and chemical additives that can leach into aquatic ecosystems. Synthetic microfibers, in particular, are durable, non-biodegradable, and prone to long-distance travel in water.

Microbeads (MBs), while less prevalent today due to bans on their use in personal care products, still persist in wastewater. Typically made from polyethylene or polystyrene, these spherical particles once replaced natural exfoliants like oatmeal and sugar in cleansers.

Although regulations have curbed their use, their historical presence remains significant in treatment systems, offering benchmarks for research and detection methods.

Technology gaps and research limitations

“We found that the effectiveness of treatments varies depending on the technology communities use and how microplastics are measured to calculate the removal rates,” said Nguyen.

She began this research as an undergraduate in Kim’s Environmental Chemistry Lab and is now pursuing her master’s at UT Arlington, working on standardized testing methods for microplastics in air and water.

Nguyen’s review highlights the lack of uniformity in how microplastics are studied. Sampling and detection methods differ widely, which can skew the understanding of how much is truly removed during treatment.

Without standard definitions for particle size, especially when distinguishing between fragments, beads, and fibers, efforts to compare studies and build effective solutions remain incomplete.

The researchers stress the need for methods that consistently capture and classify microplastics in wastewater. Current tools often miss the smallest particles or fail to identify specific polymers. As a result, data on microplastic concentrations vary depending on the treatment stage, region, and water source.

Microplastics carry harmful chemicals

Beyond their physical presence, microplastics interact with other pollutants in alarming ways. Their surface chemistry enables them to absorb and transport contaminants such as flame retardants, surfactants, and plasticizers.

These particles, once inside the environment or living organisms, can leach these absorbed toxins, intensifying their harmful effects.

MPs often act like sponges, absorbing chemicals through hydrophobic partitioning and surface interactions. Once inside water systems, they entangle with organic matter, sediments, and other particles. This complex behavior reduces their detectability and complicates removal during treatment processes.

Researchers are now calling attention to these interactions to better understand the role of microplastics in bioaccumulation and toxicity.

“This work helps us understand the current microplastics problem, so we can address its long-term health impacts and establish better mitigation efforts,” said Karthikraj Rajendiran, a co-author of the study and assistant professor of research from UTA’s Bone Muscle Research Center.

Health effects remain elusive

While aquatic ecosystems have received the bulk of microplastic research, human health effects are only starting to come into focus.

Current findings show that microplastics can enter the body through ingestion or inhalation and potentially accumulate in tissues. However, the long-term impacts on organs, hormonal balance, and cell function are still under investigation.

In wastewater systems, MFs and MBs behave differently from other microplastic forms. Their size, density, and shape influence how far they travel and what materials they entangle with.

Microfibers, with their high length-to-width ratio, form dense matrices in treatment sludge, reducing filtration effectiveness. Microbeads, with their smooth surfaces, evade capture and persist in treated water.

The lack of studies that focus specifically on these two shapes is a barrier. By addressing this gap, researchers hope to clarify how these particles behave, what risks they pose, and how best to target them for removal.

Solutions, awareness, and regulation

Public behavior can help reduce the release of microplastics. Consumers are urged to choose fabrics and personal care products free of plastic polymers whenever possible.

“While communities must take steps to improve microplastic detection and screening at the wastewater and water quality monitoring, consumers can already make a difference by choosing to buy clothing and textiles with less plastics whenever feasible, knowing that microfibers are the most common microplastic continually released through wastewater,” said Kim.

Mindful laundry habits, such as reducing wash frequency and using fabric filters, also help. Policy-level actions must follow. Governments can regulate production, enforce labeling, and promote biodegradable alternatives in fashion and cosmetics.

Education campaigns can inform the public about how everyday choices impact the microplastic loads carried in wastewater.

Action on microplastics in water

The review by Nguyen and colleagues is the first to focus specifically on microfibers and microbeads in wastewater; it combines field data, laboratory analysis, and chemical interaction studies.

It highlights the urgency of developing targeted removal technologies and crafting legislation that considers the diversity of microplastics present.

Their work received funding from UTA’s Research Enhancement Program, which is designed to support interdisciplinary teams in launching new research directions.

With increasing awareness and strategic intervention, both scientific and social, we can begin to contain microplastic pollution before its consequences become irreversible.

The particles may be microscopic, but the challenge is massive. This research pushes the conversation forward – toward cleaner water, healthier communities, and a better understanding of the unseen pollutants in our daily lives.

The study is published in the journal Science of the Total Environment.

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