We research and develop new processes for removing microplastics and micropollutants from various waters.


Micropollutants in wastewater treatment

For some years it is known that there are materials in wastewater, which can be removed only to a certain extent or not at all during wastewater treatment in municipal sewage plants. We are talking about anthropogenic trace substances or micropollutants.



Micropollutants are synthetically produced, non-natural micro contaminations, which are found in smallest concentrations of millionth (micro) to billionth (nano) gram per liter.



They are comprised of substances such as pharmaceuticals, pesticides, but also microplastics.

The totality of organic-chemical pollution can be divided into dissolved and undissolved or insoluble organic-chemical compounds. In water, each compound shows a specific type of reaction: it is either completely, partially or not at all degraded or converted.

That means, in parts micropollutants leave unhindered e.g. the three purification stages of a wastewater treatment plant and enter the ecosystem

.

Micropollutants and their environmental relevance

In recent years, an increasing number of micropollutants, which are known to have the potential to disrupt the ecosystem, have been detected in the water cycle

.

To make a qualified statement about the behavior of micropollutants in the environment and their environmental relevance,

their chemical and physical properties as well as combined environmental properties are being analyzed.

Depending also on specific environmental factors (persistence, degradability, etc.), the (eco-)toxicological influences of micropollutants can be determined

.

The dilution factor generally reduces the (eco-)toxicological influence. As a result, substances are then considered to be of reduced (eco-)toxicological relevance. Potentially a fallacy in some cases.

Micropollutants and the fourth purification step in municipal wastewater treatment plants

As many micropollutants can pass unhindered through the three treatment steps of a municipal wastewater treatment plant, there is a growing demand for an additional fourth treatment step for centralized wastewater treatment.



This shall take care of exactly those substances that could not be removed before but are potentially classified as harmful and / or dangerous to ecosystems and health.

The requirements for this fourth treatment step are complex. State of the art in municipal wastewater treatment has reached its limits.

On the one hand, the purification step must be able to remove a broad spectrum of problematic substances, the micropollutants, to a large extent. On the other hand, it is also necessary to avoid undesired by-products, which are produced, for example, by chemical or biological conversions. At least, they should be made controllable for wastewater treatment plant operators. In addition, the fourth purification step must be easy to operate for trained personnel and capable of being integrated into an existing plant. Last but not least, an appropriate, justifiable, cost-benefit factor must be met.

At present, various processes are available for the removal of micropollutants in municipal wastewater treatment plants.

These can be divided into four groups according to their respective mechanisms of action.

All methods can be combined with each other, but it must be considered that each of them has limiting factors that cannot be completely eliminated even by combining two approaches. Frequently the procedural limits are the uncertainty about by-products in oxidative processes, slip and desorption in case of powdered activated carbon, high consumption of chemical aids, economic efficiency as well as personnel or spatial capacity. Monetary investments such as construction costs are also limiting factors.
Overview about the state of the art for the removal of micropollutants from waters (here: wastewater treatment)

For this reason, we research new material compositions and processes that make it possible to remove micropollutants and microplastics in total and in one step.

One of the areas of application is the fourth purification stage in wastewater treatment plants.