What Are Emerging Contaminants in Wastewater?

Emerging contaminants, sometimes termed as contaminants of emerging concern (or CECs), are a group of chemicals which are present in the environment in initially low concentrations, but which can bioaccumulate over time and pose potential problems for the flora and fauna around them.

Emerging contaminants can be found in a wide variety of sources, from soil samples to crop yields, but they most commonly end up in water. This includes groundwater, surface water, subterranean aquifers and even drinking water. However, wastewater generally constitutes their first port of call. Here’s a brief introduction to the different types of emerging contaminants in wastewater, how they get there and their potential effects once released back into the environment.

Which emerging contaminants find their way into wastewater and how?

As with all CECs in general, those found in wastewater can arrive there from a variety of different routes. Household and industrial waste is one of the most common, with heavy metals, hydrocarbons and other potentially damaging substances leaching out of waste and into the soil surrounding it, before being washed into sewers and drains. The same thing can happen with agricultural chemicals used on fields, which are washed away during excessive rainfall.

Meanwhile, the pharmaceuticals consumed by humans and the personal care products used to primp and preen our bodies also find their way into the wastewater system. This is because although some of the chemicals present in these products are absorbed by the human body, many pass through the digestive system and are excreted out intact, while others are simply washed off us and down the plughole.

What happens next?

As the name suggests, CECs are of emerging concern because we have only recently discovered their potentially damaging properties. This means that existing wastewater treatment plants do not employ processes rigorous enough to remove all impurities from their effluent and although advances have made been in this areas – such as the advent of digital measurement in wastewater treatment – many CECs survive.

As such, they are essentially emitted back into the environment, where they are free to bioaccumulate over time. Again, research is ongoing into how best we can remove CECs from the wastewater system completely. However, the sheer number of CECs present in the natural world, alongside the prohibitive costs of implementing systems geared towards removing them, mean that this project is very much still a work in progress.

What are the effects of CECs after they pass through wastewater treatment plants?

If, as usually happens, CECs escape the wastewater treatment process unscathed, they can bioaccumulate in other water sources, such as streams, lakes and even reservoirs. As a result, they could potentially pollute drinking water sources and risk widespread exposure to human populations living in the vicinity of the wastewater treatment site.

Although the full extent of the environmental and health effects of CECs is not yet understood, there are suggestions that some of these substances could be carcinogenic, while others are endocrine disruptors and more still could have long-term ramifications for the human body which we simply cannot fathom at the present time. From an environmental perspective, emerging contaminants in wastewater can cause catastrophic imbalances in nutrient levels, thus upsetting the delicate ecosystems in aquatic environments.