Wastewater treatment plants play a vital role in protecting rivers, lakes, and coastal waters. Water must go through multiple stages designed to remove harmful wastewater contaminants. These stages make sure it’s safe before being released.
But, not every wastewater contaminant is easy to remove. Some chemicals are very stable, present at extremely low concentrations, or resist breakdown. As a result, certain substances can pass through treatment systems and enter natural water bodies.
Here are five of the most difficult wastewater contaminants to remove during treatment.
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Pharmaceuticals and Active Pharmaceutical Ingredients (APIs)
Human excretion, improper disposal of medicines, and pharmaceutical manufacturing discharge are primary ways in which residues enter wastewater.
Recent studies demonstrated that many pharmaceuticals are removed inefficiently during treatment. The removal rate for some pharmaceuticals was below 50%.
This is a concern as even at very low concentrations, these compounds can affect aquatic ecosystems. One study showed that psychiatric drugs, such as fluoxetine, alter fish behaviour. They make fish less risk-averse and vulnerable to predators.
The World Health Organisation has also highlighted the danger of antimicrobial resistance. The over-use and discharge of antibiotics is the main driver of this.
The EU is introducing a new pharmaceutical wastewater treatment rule to tackle these problems. This includes a new quaternary wastewater treatment stage targeting micropollutants like pharmaceutical residues.
PFAS (“Forever Chemicals”)
Per- and polyfluoroalkyl substances (PFAS) are often referred to as “forever chemicals”. Their carbon-fluorine bonds make them stable and resistant to degradation.
PFAS is found in firefighting foams, water-repellent fabrics, food packaging, and industrial coatings. Wastewater treatment for PFAS is very difficult. It requires advanced filtration or high-energy destruction methods.
Many treatment technologies can capture PFAS but not destroy them. So, the contamination doesn’t disappear. The PFAS has just been moved to another waste stream, such as sludge or filter media.
PFAS are now a major focus of EU water policy and monitoring programmes such as the Drinking Water Directive.
Hormones and Endocrine-Disrupting Chemicals (EDCs)
Hormones such as oestrogen and synthetic endocrine-disrupting chemicals enter wastewater through pharmaceuticals, cosmetics, and agricultural runoff.
These substances can interfere with the hormonal systems of animals and humans. Even very low concentrations affect aquatic ecosystems. Studies have shown that they can change reproductive development in fish and amphibians.
They are difficult to remove because they occur at very low concentrations. They are also often resistant to biological treatment.
Researchers across Europe are now developing new filtration and enzyme-based technologies. They aim to capture these compounds before wastewater is released into the environment.
Microplastics
Microplastics are plastic particles smaller than 5 mm. They come from cosmetic products, clothing fibres, and the breakdown of larger plastics.
Their size and variety of shapes and polymers make them a very difficult wastewater contaminant to fully capture during treatment. Older wastewater treatment systems were not designed to remove such small particles.
Even with modern treatment plants removing a large amount of microplastics, some still enter rivers and seas. Here, they can be ingested by aquatic organisms and move up the food chain.
The EU has begun mandatory monitoring of microplastics in wastewater as part of updated water regulations.
Nutrients (Nitrogen and Phosphorus)
Nitrogen and phosphorus are common in wastewater contaminant due to human waste, detergents, fertilisers, and industrial processes.
These pollutants are unique. They dissolve in water, making them harder to remove through physical filtration. Removing them requires specialised biological and chemical treatment processes.
Excessive nutrient release into rivers can cause eutrophication. This is the buildup of nutrients in water. Eutrophication causes harmful algal blooms and oxygen depletion that harm aquatic life.
Eutrophication is a primary cause of water quality decline in Ireland. It affects 27% of rivers and 35% of lakes due to excessive phosphorus. In over 70% of transitional waters, eutrophication is due to nitrogen. Agricultural runoff and wastewater are the main causes for this.
Test For Wastewater Contaminants With Southern Scientific
At Southern Scientific, we help pharmaceutical companies understand and manage the environmental impact of their wastewater. Our team of experienced analysts provides detailed testing for pharmaceutical residues, micropollutants and other emerging contaminants.
We also support organisations with regulatory compliance, including IPPC requirements, wastewater discharge licences, and evolving EU regulations on pharmaceutical pollution.
By combining advanced analytical techniques with practical environmental expertise, we help companies monitor wastewater effectively and maintain compliance with strict environmental standards.
