Development of a hybrid filter media for microplastic removal from wastewater

To develop new filter media, various modifications of standard glass fiber filtration media are investigated. Both mechanical and chemical modifications are used. Mechanical modification involves the incorporation of glass nanofibers and electrospun polymer nanofibers into the media matrix. In addition, electrospun nanofibers in and on the substrate as an additional layer will be compared. The first set of samples will be prepared by blending the nanofibers with different weight percentages of glass fibers, while the second set will be prepared by depositing the nanofibers directly on the downstream side of the substrate. The aim of these modifications is to improve the three basic filter performance characteristics: increasing the separation efficiency (SE), reducing the differential pressure (Δp) and increasing the dirt holding capacity (DHC). In addition, standard glass fiber filter media are chemically modified with appropriate surfactants. The aim of these modifications is to change the surface energy and polarity of the filter media to improve interaction with the contaminant particles. The experimental results show that the modifications can lead to significant improvements in filtration performance. In particular, increased separation efficiency for smaller particles were observed. As the amount of plastic waste in the environment is increasing and microplastic particles pose a threat to the environment and people, the modified filter media should be tested as part of the fight against microplastics. Plastic enters the environment and spreads through the air, soil and water. While large pollutants are relatively easy to deal with, small microplastic particles pose a greater challenge. Due to their small size, they are very difficult to remove using conventional filtration methods. The aim of this work is to develop a filter medium that can more effectively retain microplastics from water. To assess the filter performance of the modified media, they are first tested under laboratory conditions. This is done using a specially designed water test bench with a defined icroplastic suspension. Selected filter media modifications are also tested under real conditions in a sewage treatment plant. Due to the large number of unknown contaminants under real conditions, appropriate test methods are required to evaluate the efficiency of microplastic removal. Suitable analytical methods are needed to quantify microplastic particles in the size range invisible to the human eye. As no standardised characterisation method is yet available, this work tests, compares and evaluates different methods such as optical microscopy, SEM/EDX, fluorescence measurements, AFM-IR, Raman spectroscopy and ToF-SIMS. In addition to the use of modified filter media to filter microplastics, mechanical and chemical modifications also provide an opportunity to improve filter performance in other filtration applications. To confirm this, both modifications were exposed to additional fluid and other contaminants. The experiments were evaluated using a hydraulic oil and a sand-like contaminant. The results strongly suggest that significant improvements in filtration performance can be achieved, particularly through direct incorporation of nanofibers into the matrix and appropriate chemical modification of the surfaces, which is of great importance for the development of efficient filter media in various applications.