A few important developments in filtration technology
Ceramic membranes can now filter 200 Dalton molar mass molecules
Ceramic membranes offer an efficient mechanical separation technology for cleaning wastewater. Researchers have now developed ceramic membranes capable of separating out smaller molecules than ever before, enabling the more efficient purification of wastewater.
Researchers from the Fraunhofer Institute for Ceramic Technologies and Systems IKTS in Hermsdorf, Germany were able to significantly reduce the separation limits of the membranes and to reliably filter off dissolved organic molecules with a molar mass of 200 Dalton.
Several obstacles had to be overcome to achieve this result. To separate such small molecules reliably, a membrane was needed with pores smaller than the molecules to be separated. The Fraunhofer team developed a nanofiltration membrane with pores of <1 nanometre which can only pass water leaving behind much of the dissolved molecules and some salts. The membrane can even filter out substances like antibiotics and hormones which are present in drinking water. In addition, all of the pores had to be as similar in size as possible. “We achieved these results by refining sol-gel technology,” reports Richter, Head of Department at the IKTS.
The second hurdle was to make such membrane layers defect-free over larger surfaces. “Whereas only a few square centimeters of surface are usually coated, we equipped a pilot system with a membrane area of 234 square meters, which means that our membrane is several magnitudes larger,” said Puhlfuerss, scientist at the IKTS.
A pilot plant commissioned by Shell in Alberta, Canada, and built by Andreas Junghans–Anlagenbau und Edelstahlbearbeitung GmbH & Co. KG of Frankenberg, Germany, has been successfully purifying wastewater since 2016, which is used for the extraction of oil from oil sand.
The researchers are currently planning an initial production facility with a membrane area of more than 5000 m2. Any kind of water can be purified, including heavy metals and dissolved organic substances from agricultural applications can be also removed. For the development of the ceramic nano filtration membrane, researchers Voigt, Richter and Puhlfuerss have received this year’s Joseph-von-Fraunhofer award.