When the subject of hormones comes up, many people think of the female cycle and the contraceptive pill. However, the tiny molecules control many functions of the human body. Hormones are found everywhere humans and animals are. They are secreted naturally, used in agriculture or in medical therapies and products. Their properties are at least as diverse as their occurrence. Among other things, they regulate the energy and water balance of the human body and contribute to growth and reproduction. In medicines, they can be lifesavers for sufferers of serious illnesses, but they can also trigger diseases or affect fertility. Sleep and metabolic disorders, depression or kidney failure are just a few of many examples. The fact is that hormones are tiny but complex molecules that should not be underestimated. Even in small quantities, they can influence basic human functions.

People ingest these small amounts not only consciously through medicines, for example, but often also unknowingly through contaminated water. "We have been recording a consistent increase in micro pollutants in water for years. In addition to pharmaceuticals, biocides, and other chemicals, these are also hormones, for example, through excretion via urine, discharge of industrial wastewater, or from residues in agriculture," explains Prof. Dr.-Ing. Andrea Iris Schäfer, head of KIT's Institute for Advanced Membrane Technology (IAMT). Nanofiltration and reverse osmosis have proven to be efficient methods for removing various pollutants from water, but reach their limits when it comes to hormones. Hormones are relatively small, and are also neutral and cannot be filtered via a charge, as it is practiced for many other pharmaceuticals. "It is fascinating that hormones can do such a precise job in the human body. They are in the right place on time, in the right amount, to perform certain functions. But removing the hormones from bodies of water just as precisely has not been possible until now," says Schäfer.

 

In order to remove these substances effectively from various water streams, the IAMT has set itself the goal of developing appropriate processes for water purification. In cooperation with a team of researchers from the Leibniz Institute for Surface Modification (IOM) in Leipzig, membranes are being modified and developed specifically for the removal of steroid hormones. "We are taking advantage of a technology from photo catalysis in the approach. The membranes are coated at the IOM," Schäfer explains. When exposed to light, these titanium dioxide nanoparticles on and in the membrane pores cause a chemical reaction in which the hormones are decomposed and made degradable. The result is a photocatalytic membrane filtration system that removes steroid hormones in a continuous flow. The process is not only energy efficient, but also reduces hormone concentrations in the filtered water. "Even though we are still in the middle of research, our technology is a major milestone and an important foundation for future water purification. The current WHO drinking water guideline is one Nano gram per liter for the hormone estradiol. Typically, around 100 Nano grams per liter are detected in treated wastewater, which means we need to remove 99 percent. This is a challenge that we can now meet," says Schäfer, describing the potential of the technology.

The researchers are working with many collaborative partners in Germany and abroad to further develop their technology and make it usable for other pollutants. "There continue to be pollutants that are still not degradable, including 'forever chemicals.' These are industrial chemicals such as per- and polyflouroacryl substances (PFAS). We want to do our part and try to understand how we can attack such stable chemical compounds," says Schäfer. In parallel, however, the research team is also working on scaling up the technology for industrial scale and looking for suitable industrial partners. Here, the introduction of light into membrane modules is a major challenge, which the team is working on with cooperation partners such as Prof. Bryce Richards from the Institute for Microstructure Technology (IMT) and the Light Technology Institute (LTI) of KIT. The photocatalytic membrane filtration system is suitable for a wide range of application examples, from water treatment plants to the processing of concentrates produced by other processes.

 

Whether further development or industrial scaling: For the researchers, the focus is on the goal of clean drinking water. "Drinking water quality in Germany is generally very good, but in other countries it is quite different and increasing contamination affects us all. Water pollution is and will remain a key global issue as it continues to increase. We cannot make water, we can only make it clean. If we do not remove micro pollutants like hormones efficiently, it is only a matter of time before we absorb them through drinking water," warns Schäfer.

Further links

• Institute for Advanced Membrane Technology (IAMT)

Images: Amadeus Bramsiepe / KIT