Sep 8 2020
On a global scale, micropollutants lead to water contamination. One of them is the steroid hormones that cannot be removed easily through conventional processes.
KIT researchers have developed a filtration system with smallest carbon particles, which removes hormones from drinking water. Image Credit: Sandra Göttisheim, KIT.
At Karlsruhe Institute of Technology (KIT), scientists have currently designed a novel filtration system made by combining a polymer membrane with activated carbon.
Since the carbon particles are very tiny, it is feasible to achieve the reference value of 1 ng estradiol—the physiologically most effective estrogen—per liter drinking water recommended by the European Commission. The enhanced technique has been described in the Water Research journal.
One of the huge challenges of the 21st century is providing people across the globe with clean water. Drinking water is usually contaminated with micropollutants. One of them is the steroid hormones utilized as contraceptives and medical substances.
Although their concentration in one-liter water into which treated wastewater is fed may only be a few nanograms, even such minuscule amounts may harm human health and impact the environment.
As a result of the small size and low concentration of the molecules, steroid hormones are difficult to detect as well as hard to eliminate. Traditional sewage treatment technologies are not enough.
Reference Value of the European Commission is Reached
The Head of KIT’s Institute for Advanced Membrane Technology (IAMT), Professor Andrea Iris Schäfer, and her colleagues have developed a novel technique for rapid and energy-efficient removal of steroid hormones from wastewater. Their technology involves using a polymer membrane in combination with activated carbon.
First, water is pressed through a semipermeable membrane that eliminates larger impurities and microorganisms. Then, water flows through the layer of carbon particles behind, which bind the hormone molecules.
Andrea Iris Schäfer, Professor and Head, Institute for Advanced Membrane Technology, Karlsruhe Institute of Technology
Scientists at IAMT have further advanced and optimized this process in collaboration with filter manufacturer Blücher GmbH, Erkrath. Collaborators from KIT’s Institute of Functional Interfaces (IFG), Institute for Applied Materials (IAM), and the Karlsruhe Nano Micro Facility (KNMF) assisted this further advancement by characterizing the material.
This has been reported by the researchers in the Water Research journal. “Our technology allows to reach the reference value of 1 nanogram estradiol per liter drinking water proposed by the European Commission,” added Schäfer.
Particle Size and Oxygen Concentration Are Important
Researchers analyzed the processes that occur in the activated carbon layer elaborately and utilized modified carbon particles (polymer-based spherical activated carbon, or PBSAC).
It all depends on the diameter of the carbon particles. The smaller the particle diameter is, the larger is the external surface of the activated carbon layer available for adsorption of hormone molecules.
Matteo Tagliavini, Study First Author, Institute for Advanced Membrane Technology, Karlsruhe Institute of Technology
In an activated carbon layer with a thickness of 2 mm, the team reduced the diameter of the particles from 640 to 80 µm and successfully removed 96% of the estradiol from the water. The oxygen concentration in the activated carbon was increased to further enhance the adsorption kinetics, thus achieving an estradiol separation efficiency of over 99%.
The method allows for a high water flow rate at low pressure, is energy-efficient, and separates many molecules without producing any harmful by-products. It can be used flexibly in systems of variable size, from the tap to industrial facilities.
Andrea Iris Schäfer, Professor and Head, Institute for Advanced Membrane Technology, Karlsruhe Institute of Technology
Journal Reference
Tagliavini, M., et al. (2020) Polymer-based spherical activated carbon – ultrafiltration (UF-PBSAC) for the adsorption of steroid hormones from water: Material characteristics and process configuration. Water Research. doi.org/10.1016/j.watres.2020.116249.