Microplastics and forever chemicals are polluting our water – what can engineers do?

When it comes to pollution, civil engineers’ focus is most often on reducing carbon dioxide emissions from our buildings and infrastructure.

But what may be less obvious is how they can help tackle other types of pollution.

Microplastics and PFAS (or forever chemicals) are becoming industry hot topics. These pollutants negatively affect the environment and living beings and they aren’t normally monitored.

This makes them emerging contaminants.

Civil engineers are one of the first lines of defence to stop or slow this contamination.

What are forever chemicals?

Forever chemicals are technically known as PFAS: per/polyfluorinated and per/polyfluoroalkyl substances.

They are forever chemicals because they are highly resistant to biodegradation, the process by which microorganisms break down organic matter.

This is because these substances are unaffected by heat, oil, and water.

This makes them useful for a range of applications due to their hardwearing abilities.

Every decade has seen a different use of PFAS. Today, they are found in non-stick cookware, textiles, cleaning products, personal care products, pesticides, and firefighting foam.

What are microplastics?

Microplastics are pieces of plastic smaller than 5mm in size.

These normally come from larger pieces – like plastic bags, tyres or water bottles – that break down from the sun’s UV rays or from wear and tear (abrasion).

One reason why microplastics are dangerous is because they can pierce through and embed themselves within organs, which affects their function.

Another reason they can be damaging is because they form biofilms around themselves.

These biofilms harbour microorganisms and bacteria but can also collect and transfer other pollutants such as heavy metals to living beings. Above certain levels, heavy metals can be toxic.

Why should civil engineers care?

These contaminants can harm the environment and the living beings within it, including humans. This is especially the case when they’re present in high concentrations.

PFAS and microplastics can also impact marine wildlife, which not only reduces their population but also creates a pathway to transfer these pollutants to humans.

As civil engineers, we have the power to put in place methods to remove these pollutants in our designs.

What can civil engineers do?

These contaminants come from various sources, such as domestic use, roads, airports, and industrial manufacturing facilities.

There are many ways to capture these contaminants and protect water courses.

Currently the main method is via water treatment processes.

For example:

• Tertiary treatment filters, which can filter out larger pollutants.
• UV disinfection, which triggers chemical compounds to breakdown.
• Advanced Oxidation Processes (AOP), which breaks down pollutants via oxidation.

These methods are generally expensive to install or operate. As civil engineers we need to identify more cost-effective methods to remove these contaminants.

Enter nature-based solutions

The best solution would be to replace these pollutants. However, more time and research is needed to identify cost-effective solutions.

The next best option is to catch these pollutants at a point before their impact is widely felt. This is possible for microplastics but still challenging for PFAS.

A large proportion of these contaminants is transported into our waterways through surface runoff. So there are several nature-based solutions (NBS) we can use.

Not only do NBS help reduce the impact of climate change and the demand on our water systems due to increased rainfall, but they also create a greener environment by reducing the spread of contaminants.

Sustainable drainage systems (SuDS) are great, low-maintenance and cost-effective techniques.

For example, swales provide a channel where water can sit and be purified by vegetation and soil.

Installing swales along the edge of roads can prevent microplastics produced by tyre skids from entering water courses and onwards to the ocean, reducing the likelihood that they will affect aquatic ecosystems.

Wetlands are also a great solution as they can capture a range of contaminants.

For example, vegetated wetlands (covered in plant life) show a decrease in PFAS concentrations within surface runoff.

The issue with these solutions is that they don’t remove the contaminants from the environment.

They simply stop them from entering areas where they’ll cause serious harm to the aquatic ecosystem, but they’re still there.

What do civil engineers need to be able to help?

Civil engineers today need to be aware of these contaminants.

They also need a willingness to learn and a passion for innovation, especially as we learn more about this topic every day.

We must understand the risks these contaminants pose to us and the environment.

This knowledge is what will ensure we limit, reduce, and eliminate this type of pollution, and others that emerge.