A model of bacterial filtration on fibrous filter media is developed. The single fibre efficiency as well as the efficiency of the whole filter - at the onset of the process and the evolution of those quantities - are analysed. The differences between the numerical modelling of colloidal particles and bacteria are stressed in detail. The main differences are the active motion ability of bacteria and biofilm formation. The parameters of the model were identified based on the literature data.

In this paper, three methods of sterilisation are compared to determine their usability in nanobubble dispersion sterilisation: filtration, thermal sterilisation and sonication (in two systems: using a sonotrode and sonication bath). Nanobubble dispersions are most commonly generated in non-sterile systems which precludes them from use in most biological research. As a result of this study, filtration was chosen as the best method for nanobubble sterilisation.

Filtration is one of the most efficient methods of removing Al2O3 inclusions from liquid steel. The efficiency of this process depends on the physicochemical parameters of liquid metal, inclusion and properties of the applied filters. The particles attracted during filtration undergo agglomeration, collisions and chemical reactions on the filter surface, with the emphasis on the mechanism of particle collisions and the role of material from which the filter was made. The aluminum oxide inclusions collide with the filter surface and as the growing process continues, the particles also collide with the previously adsorbed inclusions. At the interface of particle and filter the mixing of the metal bath is most intense, being a result of a sudden change of flow direction and breaking up the stream of liquid metal which is in a direct contact with material. The efficiency of filtration is defined not only by the behavior of individual particles but of all population. The simulations revealed that only a small fraction of these particles adheres directly to the filter material; most of them stick to the former ones. Attention should be also paid to the fact that some of the inclusions which contacted the filter walls do not form a permanent connection and are then entrained by metal. Authors solved the problem of agglomeration and collisions of Al2O3 inclusions with the ceramic surface of the filter with the PSG method, mainly used for the analysis of agglomeration of inclusions during steel refining in the ladle.

Filtration process is one of the basic and essential processes in technological systems for treatment of municipal, community and industrial wastewater treatment. Filtration process is a subject of numerous published research and theoretical elaborations. This publication concerns theoretical analysis with basic character, and is a verification of theoretical analysis and physical equations describing process of filtration aided with empirical formulas.

Water is a strategic material. Recycling is an important component of balancing its use. Deep-bed filtration is an inexpensive purification method and seems to be very effective in spreading water recovery. Good filter designs, such as the fibrous filter, have high separation efficiency, low resistance for the up-flowing fluid and high retention capacity. However, one of the substantial problems of this process is the biofouling of the filter. Biofouling causes clogging and greatly reduces the life of the filter. Therefore, the melt-blown technique was used for the formation of novel antibacterial fibrous filters. Such filters are made of polypropylene composites with zinc oxide and silver nanoparticles on the fiber surface. These components act as inhibitors of bacterial growth in the filter and were tested in laboratory and full scale experiments. Antibacterial/bacteriostatic tests were performed on Petri dishes with E. coli and B. subtilis. Full scale experiments were performed on natural river water, which contained abiotic particles and mutualistic bacteria. The filter performance at industrial scale conditions was measured using a particle counter, a flow cytometer and a confocal microscope. The results of the experiments indicate a significant improvement of the composite filter performance compared to the regular fibrous filter. The differences were mostly due to a reduction in the biofouling effect.

Trials of cast steel filtration using two types of newly-developed foam filters in which carbon was the phase binding ceramic particles have

been conducted. In one of the filters the source of carbon was flake graphite and coal-tar pitch, while in the other one graphite was

replaced by a cheaper carbon precursor. The newly-developed filters are fired at 1000o

C, i.e. at a much lower temperature than the

currently applied ZrO2-based filters. During filtration trials the filters were subjected to the attack of a flowing metal stream having

a temperature of 1650°C for 30 seconds.

Characteristic of the filters’ properties before and after the filtration trial were done. It was found, that the surface reaction of the filter

walls with molten metal, which resulted in local changes of the microstructure and phase composition, did not affect on expected filter

lifetime and filtration did not cause secondary contamination of cast steel.

Extremely intense development of civilization requires from foundry casting technologies very high quality and not expensive castings. In

the foundries, there are many treatments that allow increasing of the final properties of produced castings such as refining, modification,

heat treatment, etc. One of the methods of increasing the quality of the casting by removing inclusions from the liquid alloy is filtration.

The use of ceramic-carbon foam filters in filtration process is still analysed phenomenon that allows improving the final properties of

castings. A modern method of research, testing and synthesis of innovative chemical compositions allows improving the properties of such

filters. In the paper the evaluation of application properties of developed ceramic-carbon bonded foam filters is presented. The quality of

the foam filters is evaluated by Computer Tomography and foundry trials in pouring of liquid metal in test molds. Additionally computer

simulations were made to visualize the flow characteristics in the foam filter. The analysed filters are the result of the research work of

Foundry Research Institute and the Institute of Ceramics and Building Materials, Refractory Materials Department in Gliwice.

The melt cleaning is an important aspect in the production of high-quality aluminum castings. Specifically inclusions within the melt and an excessively high hydrogen content lead to defects and undesired porosity in the castings. Although it is possible to reduce the amount of hydrogen and oxidic inclusions by purge gas treatment and the use of melting salts, it is impossible to remove oxides (bifilms) created during filling of gating system. Paper deals with the effects of melt quality and the placement of a filter in the filling system on Al-7%Si-Mg alloy mechanical properties. Three different filters were used: (a) rectangular ceramic pressed filter with 3 mm thickness (b) cubical pressed ceramic filter with thickness 10 mm (c) cubical pressed ceramic filter with thickness 22 mm. The results showed that the highest tensile strength values were obtained from the filter with thickness of 22 mm. Numerical simulation analysis of the filling process showed that velocity reduction by filter is the major phenomenon affecting the mechanical properties. Another evaluated aspect during experiments was capability of filters to retain old bifilms. For this purpose multiply remelted alloy was prepared and analyzed. Results showed that filter efficiency increases with decreasing melt quality as a result of possibility to retain “old” bifilms better than small and thin “new” bifilms.

Applications of morphological filters for two-process profiles were analysed. Dilation, closing and alternating sequential (closing +  opening) filters were used with a circle (disk) as a structuring element. An original method of a disk radius selection was elaborated for two-process profiles. This procedure was applied for many simulated and measured profiles. Behaviors of morphological filters were compared with those of double Gaussian (Rk) filter. Robust filter was also taken into consideration. In calculation, TalyMap software was used. The proposed procedure was found to be very useful. It was developed for 2D profiles but it can be easily extended for an areal (3D) surface topography filtering. From among morphological filters, the alternate sequential filter is suggested.

The aim of the study was to determine the influence of the load on the water accumulation embankment crown on changes in the course of the filtration curve in its body. The study was carried out with a medium-size filtration apparatus. We made a model of hydrotechnical embankment with the following dimensions. Width: base 2.0 m, crown 0.5 m. Slope inclination: waterside 1:1.5, landside 1:1. Embankment height 0.6 m, width 1.0 m, weight 900 kg. The construction mater-ial included a homogeneous mineral subsoil classified as silty medium sand (siMSa). The embankment model made in a medium-size apparatus kept the accumulation level at a height of 0.5 m. With data from the recording systems, we deter-mined the course of the filtration curve. Next, we kept on loading and relieving the embankment crown using an actuator and a VSS plate with a diameter of 300 mm. During this process, we recorded changes in the level of the water table inside the embankment. A decrease in the water table was observed as a result of increased load. Once the load on the embankment crown was reduced, the water level inside the embankment increased. The embankment model built from natural soil works well as a structure that keeps damming water in a continuous manner. The use of drainage in the form of a stone prism at the foot of the landside slope allows protecting the slope against the negative influence of filtration (piping, lique-faction).

The aim of the study was to analyze and assess the possibility of using a two-stage filtration system with ceramic membranes: a 3-tube module with 1.0 kDa cut-off (1st stage) and a one-tube module with 0.45 kDa cut-off (2nd stage) for treating effluent water from a juvenile African catfish aquaculture. The study revealed that during the 1st filtration stage of the effluent water, the highest degrees of retention were obtained with respect to: suspended solids SS (rejection coefficient RI=100%), turbidity (RI=99.40%), total iron (RI=89.20%), BOD5 (RI=76.0%), nitrite nitrogen (RI=62.30%), and CODCr (RI=41.74%). The 2nd filtration stage resulted in a lower reduction degree of the tested indicators in comparison to the 1st filtration stage. At the 2nd stage, the highest values of the rejection coefficient were noted in for the total iron content (RIV=100%), CODCr (RIV=59.52%; RV=64.28%, RVI=63.49%) and turbidity (RIV and RV = 45.0%, RVI=50.0%). The obtained results indicate that ceramic membranes (with 1.0 and 0.45 kDa cut-offs) may be used in recirculation aquaculture systems as one of the stages of effluent water treatment.