Emerging contaminants in wastewater and receiving surface water environments

We have a role in educating Victorians about the discharge of wastewater to surface water environments. We work with the following to understand and act on potential risks of harm to human health and the environment:

• government partners
• industry
• academic institutions.

Background

We typically assess the risks of emerging contaminants to the environment using targeted chemical analysis. This is for a subset of chemical groups, often limited to several hundred substances. Yet, wastewater discharges are known to contain mixtures of thousands of chemicals. So, the identification of new tools to assess the risks is warranted.

Emerging contaminants are natural or man-made chemicals that may pose a risk to our health or the environment. These, for example, include:

• pharmaceuticals and personal care products (PPCPs)
• pesticides
• phthalates
• industrial chemicals.

They are called emerging because we are still learning about:

• their presence
• how they behave
• what effects they might have on the environment.

Our research

In 2024, we led a study on emerging contaminants in wastewater discharges to the environment. The study builds on our previous work on emerging contaminants (publication 2054).

To help Victoria’s broader water sector, this project trialled the use of effect-based monitoring techniques. This was to holistically assess risks associated to emerging contaminants in wastewater discharge.

The study analysed samples at 4 wastewater treatment plants across Victoria. It used a combination of bioassays and targeted analysis. The study also collected water samples up-and downstream from the treatment plants.

What we found

The study found 104 chemicals in treated wastewater, including:

• artificial sweeteners
• endocrine disrupting chemicals (EDCs)
• pesticides
• per- and polyfluoroalkyl substances (PFAS)
• phthalates
• pharmaceuticals and personal care products (PPCPs).

This result is consistent with similar studies conducted in other parts of the world.

Bioassay results showed that wastewater treatment plants could remove the majority of active chemicals. Thus, reducing environmental impacts. But this reduction was compound specific and varied across contaminant groups.

Concentrations of emerging contaminants were lower in treated wastewater than in raw sewage. This matches our previous work. Yet, some compounds that went through the wastewater plants were mostly untreated.

In surface waters, downstream of wastewater discharge, the study detected:

• artificial sweeteners
• EDCs
• PFAS
• pesticides
• PPCPs
• phthalates.

This study also found the presence of PFAS, pesticides and phthalates upstream of wastewater discharge. This indicates that, apart from wastewater, there are other sources for some of these chemical groups.

What this means

Using bioassays, this study was able to identify adverse effects to the receiving surface water environment at specific sites. Yet, a bioassay response does not always mean there are unacceptable risks to the environment. Further site-specific assessments should occur.

The effect-based methods offer a holistic tool to help the water sector:

• develop Risk Management and Monitoring Programs (RMMPs)
• meet their general environmental duty requirements.

Next steps

We continue to work with partners to:

• build state of knowledge
• improve understanding of the effects of emerging contaminants to the environment
• develop solutions.