Professor, Faculty of Chemical and Process Engineering, Warsaw University of Technology, Poland

Biography: Dr. Leon Gradoń is the tenure Professor of Chemical Engineering at Warsaw University of Technology. With 45 years of academic and research experience, he is author and co-author of 19 monographs and chapters, 4 academic books, over 220 per-reviewed papers in scientific international journals, over 250 publications in the conference proceedings and 65 patents. Several applications of his inventions at technical scale: deep water filters, bag filters, diesel engine filters, ultrasonic neubulizer, pneumatic nebulizer, disposable respirators and dry powder inhaler. Editorial Board Member in four international journals: Chemical and Process Engineering Journal, International Journal Occupational Safety and Ergonomics, Journal Aerosol in Medicine, KONA – Powder and Particles and Advanced Powder Technology.

Speech Title: Reduction of biofouling effect in composite fibrous depth filters
Aims: The deep-bed filtration technique is one of the most effective available water purification methods. The real fibrous filter properties emphasize during its loading, when the deposits gradually change a filtration space. One of the substantial negative effects occurring during filtration is the biofouling phenomena caused through natural growth of deposited microorganisms collected in the filter. This process could be reduced through modification of the polymer fibers forming the depth filter with introduction on their surface the nanoparticles of selected metals and/or oxides.
Methods: The melt-blown technology was used for the formation of novel antibacterial fibrous structures. Such filters are made of polypropylene composites with nanoparticles of silver and/or zinc oxide. Particle with controlled final surface concentration are introduced into fibers in the nozzle region of fiber formation. Another composite was made with the hydrothermal process of growth of ZnO nanorods on already formed fibers. With this method we are able to control surface concentration and morphology of nanorods. Antibacterial/bacteriostatic tests were performed on Petri dishes with Escherichia coli and Bacillus subtilis bacteria and in the full scale of filtration process using flow cytometry and confocal microscope.
Results: Biofouling effect is significantly reduced in the composite filters in comparison to the results obtained for nonmodified fibers. Reduction degree depends on the nanoparticles concentration and their morphology and is in the range of 70% to 95%. It causes the prolongation of the filter lifetime.
Conclusions: Proposed methods of modification of polymer fibers with introducing on their surface of metal or oxide nanoparticles or nanorods is very promising technology of active composite formation for effective filtration of biotic and abiotic objects.