Osmotic membrane research with roots in Chinese philosophy

Osmotic membrane research with roots in Chinese philosophy

Henrik Tækker Madsen shares his time and employment between two highly esteemed research environments: The Section for Sustainable Biotechnology at the Department of Chemistry and Bioscience, Aalborg University Copenhagen, and the company Applied Biomimetics that develops aquaporin-based membranes where biological membrane proteins  – called aquaporins – are incorporated into synthetic membranes in order to improve the membranes’ ability for water filtration. He has chosen this model of employment to be able to apply his research to solve the overall challenges that industry and society are facing – now and in the future:

- “Here at AAU, we educate engineers – and in order to do that, you need to know what it means to be an engineer in a company. It is one thing to communicate the latest research to our students, but engineering holds a much more practical dimension that the students need to learn, too. Otherwise you may be in a situation where you work on something that is highly interesting in terms of research value but where you overlook some of the practical challenges which may in the end prevent a technology from being applied in practice in companies and in our society. By having a foot in both camps, I get insight into both aspects” Henrik Tækker Madsen explains.


In his own research work, Henrik Tækker Madsen draws on two major sources of inspiration: Nature itself – and ancient Chinese philosophy.

- “In Chinese philosophy, two of the major lines of thinking are Confucius, whose thinking concerns bending nature to your will, and Taoism, which concerns bending with nature. If you apply these two philosophies to membrane filtration, you could say that the classical method can be seen as following Confucius’ thinking. You place a filter in water and use a pump for applying pressure to force the water through a filter. This works well, but it also has its challenges, as the membrane will clog up and there are limits to the amount of pressure you can apply” Henrik Tækker Madsen explains.

- “Now, osmotic membrane filtering is more in step with Taoism. You leave the process to happen on its own. You have a membrane between, on the one side, the solution you want to filter, and on the other side a high-percentage solution of salt or sugar. Nature works in this amazing way that water will travel from the solution we want to filter and into the highly concentrated solution – in other words, it moves through the membrane of its own power. This gives us an entirely different filtration process that is much gentler and careful – and much more elegant and natural” he adds.


Traditionally, the Danish drinking water sector use sand filtration for removing unwanted elements, including pesticides, from our drinking water. This technology was invented in the 1800s, and according to Henrik Tækker Madsen, it is time for a change for the better – not just for the sake of our drinking water but for the sake of Denmark’s position on the global market for water treatment technology.

- “Sand filtration isn’t rocket science – it is something that the Chinese can just as easily do and outcompete us. We need to do something more, and a few years back I met a group of researchers from Aarhus University who were working on using bacteria for removing pesticides from drinking water. Their challenge was that the concentration of pesticides in the water was so low that the bacteria would starve after a while, and this was an obvious opportunity for us to combine the two technologies” Henrik Tækker Madsen explains. This led to a project funded by Innovation Fund Denmark in which nanofiltration will be used as a first step to clean out the pure water from the water with pesticides in it. This will result in a solution with a high concentration of pesticides, into which the researchers will add a sand filter with bacteria that can thrive in the higher concentration of pesticides and consume them.

“If we succeed with this project, we will have a technology that enables us to remove pesticides without the use of chemicals. We aim at a technology that can be used as an add-on element to existing waterworks as an alternative to the current technology which is activated carbon” Henrik Tækker Madsen adds.


But the value generated by osmotic nanofiltration does not stop at giving us more environmental-friendly water treatment. Henrik Tækker Madsen is currently working on a major project with industrial partners including Danfoss and Japanese membrane manufacturers. In this project, membrane-based processes are used to generate power from geothermic water, and the vision is to develop a system that can be used in geothermic plants all over the world. In short, geothermic power plants function by drilling 1-2 kilometers down into the earth to draw up heated water from a water-carrying layer. The water in this layer is 50-70 degrees warm and has, in Denmark, a salt concentration of between 15% and 30%.

- “What we want to do with this technology is 1) extract heat from the water to generate district heating and 2) create power from osmotic processes using the geothermic salt water on one side and fresh water on the other side of a membrane. You could say that it is a new, modern version of our combined heat/power plants – only completely CO2-neutral” Henrik Tækker Madsen explains and elaborates: “Now, as we need fresh water for the osmotic process that generates the power, why not utilize the ability of the osmotic process to separate fresh water from wastewater? So the system will consist of a power-generating osmotic membrane system that we plug into our wastewater plants, resulting in 1) heat, 2) CO2-free power, 3) wastewater treatment ensuring no disposal in our fjords or seas, and 4) a now highly concentrated last amount of wastewater that can be transported to biogas facilities to be used for generating even more green power.”


This may sound like another researcher vision that will not see the light of day in many years, but the system is in fact almost ready for testing on a major scale – and has recently been appointed Danish Engineering Achievement of the Year by the readers of the Danish newspaper Ingeniøren. “Our pilot facility in Sønderborg has been up and running for almost a year now, and it looks very promising. We are currently working on upscaling it to a much bigger facility that will be the first of its kind in the world” Henrik Tækker Madsen says and finishes:

“The technology is actually fairly close to being commercialized and offered to actual power plants. We can build the system inside containers – we call it salt power technology – which can be connected to existing geothermic plants all over the world and enable the power plants to produce green power along with the geothermic heat. In this way, all the technologies come together in an elegant solution that benefits nature as well as our society.“