Laboratory of separation processes focuses on the development and implementation of innovative filtration technologies for various applications. Our work is motivated by the desire to minimize the impact of industrial and agricultural activities on the environment and human health while maximizing the efficiency and sustainability of our solutions.

One of the project is to develop and validate a compact filtration unit for 3D desktop printers in the form of a cover box. This box contains a hollow fibre membrane based filter and a carbon filter, the exhaust is routed through the hollow fibres and can be operated in air recirculation mode. This box enclosure with a filter based on hollow fibre membranes with an extraction path through these fibres and a carbon filter with air recirculation. The use of an enclosure with active filtration and air recirculation prevents user exposure to emissions from 3D desktop printers (reducing health risks), reducing the risk of printing errors when cooling the printer area and reducing printer power consumption due to cooling of the print pad and thus increasing the power input for heating. The use of a hollow fibre membrane with a high surface area and very small pores allowed to achieve high filtration efficiency and to reduce the fouling rate, i.e. to extend the service life. The only disadvantage appears to be the higher resistance of the

membrane, which can be eliminated by using interval filtration (e.g. 2 h. stop, 10 min. filtration). In addition to the main result, an extensive database of data from measurements during printing from different types of filaments will be obtained.

One of the projects focuses on the development of a filtration system for high temperature flue gas filtration for biomass boilers and similar applications up to 450 °C. Current solutions exist in the form of fabric filters (only up to 250 °C), which have a high risk of combustion and therefore very limited use, or ceramic filters, their cost is extremely high for higher extraction rates. The use of special non-woven stainless steel fibre felt will result in the development of filtration equipment with unique properties. The stainless steel non-woven felt will have a lower pressure drop compared to ceramic elements without a significant decrease in filtration efficiency. Due to the higher permeability, it can also be expected to be easier to regenerate with lower compressed air consumption, which is a very expensive commodity. They will not be fragile, so it is possible to use larger sizes (2 meters or more) which are more difficult to handle during servicing and which will not be at risk of bursting. Due to the electrical conductivity of these materials, it will be possible to ground the entire filter housing and use it for filtration in explosive environments (e.g. pyrolysis gas filtration), which is not possible with ceramic filters. The same applies to the filtration of air with high oil aerosol content, where ceramics cause clogging without the possibility of regeneration. Stainless steel felt have a certain degree of flexibility and can therefore be geometrically optimised.

The goals of the project are:

1. Verification of the efficiency and pressure drop of stainless steel mesh-based filter materials

2. Possibilities of geometric optimization of stainless steel mesh filter elements

3. Studying the fouling and regeneration efficiency of these elements

4. Testing of the above characteristics on the developed equipment in operation

5. Analysis of advantages/disadvantages, price/performance ratio

Laboratory is also involved in developement of a comprehensive technology capturing ammonia nitrogen from wastewater from industrial and agricultural activities, waste water treatment plants, biogas plants, seepage water from municipal waste landfills and its transformation into a reusable form of ammonia fertilizer with gradual release of nutrients. The technological device based on the proposed process, which combines classical chemical engineering operations with membrane technology, achieves both higher effluent purity and valuable recycled and marketable products, as well as reduce the amount of waste disposed of in landfills or discharged into the atmosphere. To achieve its objectives, the project applies the use of a system of porous and non-porous thin-walled hollow capillaries (fibres) as part of a complex technology, which, although currently being developed in membrane processes, are still relatively little used in practice. Fiber bundles can be used both for the actual separation of desired salts from solutions and for revitalization steps in wastewater treatment. The potential of this type of membrane technology is enormous, both in terms of the efficiency of the separation processes and the low investment and, more importantly, operating costs, as well as the possibility of application in diverse fields.

More information is available at: https://www.heatlab.cz/research/separation-processes/