Many regions in the world rely on water filtration systems to remove contaminants and produce clean drinking water. Contaminants are removed by passing the dirty water through membranes with tiny pores that reject larger components. However, a layer of fouling material accumulates on these membranes over time, where it obstructs flow and increases the energy demand of the purification process.
Due to the increasing scarcity of freshwater sources in the future, the production of clean and safe drinking water is a crucial global problem to address. Chemical cleaning of the fouling layer damages the filtration membranes and affects water quality. Novel and environmentally friendly solutions for fouling control are therefore essential for safe access to clean water. Such solutions require intimate knowledge about the composition of the accumulated fouling layers.
A dominating fraction of the fouling layer is composed of large bacterial colonies - termed biofilms – where the bacteria have increased resistance to chemical and mechanical stress. These properties emerge from the self-produced extracellular matrix embedded inside the bacteria. If we could selectively degrade the macromolecules of the matrix using enzymes, we could dissolve these fouling layers and save the water filtration process enormous amounts of energy.
Using the novel imaging method of optical coherence tomography, we have designed an enzyme screening platform, making it possible to test different enzyme combinations for removal of membrane biofilms. Using this screening platform, we can elucidate which macromolecules are responsible for the structural integrity of the biofilms and learn how the biofilms gain their increased resistance to stress.
Development of the enzyme screening platform is part of an industrial PhD study at Aarhus University Center for Water Technology, WATEC and is conducted in collaboration with the Danish biotech company Novozymes A/S.
Novozymes contributes, among other things, with research facilities and about 60 enzymes to be tested with the aim to identify the enzyme combinations that most efficiently remove the membrane biofilms.