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The flow behaviour of liquid foam is of central importance in froth flotation for mineral processing. Flotation separates valuable mineral particles from gangue material based on the surface wettability. To this end, the solids are finely ground and suspended in an aqueous solution with flotation reagents. In aerated flotations cells, gas bubbles selectively attach to the hydrophobic mineral particles, rise to the surface, and form a froth. To recover the valuables, they are transported out of the flotation cell with the froth. In flotation plants, the recovery of solid and liquid is monitored by optical observation of the overflowing froth. However, this monitoring is limited to the free surface of the particle-laden froth. Aiming for detailed insights into the flow behaviour underneath the surface-near foam bubbles, the laboratory-scale experiment in this work investigates the velocity field of an overflowing foam in combined optical and X-ray measurements. For this purpose, foam was generated continuously, moved similar to a plug-flow in a vertical channel with rectangular cross-section, and flowed off over a one-sided horizontal weir into the open surrounding. The imaging measurements focused on the foam flow in the region of interest around the weir. Simultaneously, the liquid fraction of the foam was monitored by measuring its electric conductivity between electrode pairs mounted near the weir. We used aqueous foams of two different surfactant concentrations but similar bubble size range and superficial gas velocity, yielding around 10 % liquid fraction. The optical measurements carried out through the transparent side wall of the flow channel as well as at the free surface of the overflowing foam. They captured light reflections on the foam bubbles were analysed by an adapted particle image velocimetry algorithm. While the opacity of the foam limits optical measurements to the wall- or surface-near foam bubbles, our approach of X-ray particle tracking velocim

Froth flotation, widely used in the processing and recycling of ores and raw materials, employs hydrophobic interactions between bubbles and particles to concentrate valuable materials in an overflowing froth phase. The flotation process, and therefore the quality of separation, is affected by the height of the 3-phase foam, called froth, and thus by the foamability. Within a joint European industry doctorate program between the Institute of Fluid Dynamics, HIF and TU Dresden, we have carried out a collaborative measurement campaign to collect data for modeling flotation subprocesses under varying hydrodynamic and reagent conditions using a laboratory scale flotation cell and a binary pyrite-quartz particle system. Froth phase measurements included the recording of the froth height through the transparent side wall of the flotation cell and imaging of the froth surface as well as foamability measurements of feed and tailing samples by means of dynamic foam analysis and measurement of the liquid fraction of the froth based on its electrical conductivity. Preliminary results show a significant change in froth properties during the flotation process from a particle-laden froth to finer bubbles containing fewer particles. Further data analysis is planned to investigate the influence of frother and collector concentrations as well as air flow rate and impeller tip speed on the foamability and froth height, impacting the recovery and grade of minerals. Such joint froth studies between the Institute of Fluid Dynamics and HIF belong to the sciences cases perspectively to be intensified by CeRI2, one of the HZDR research infrastructure projects.

Microalgae are becoming increasingly important for numerous applications such as food or pharmaceutical products. Flotation is an effective and comparatively inexpensive process for dewatering of the algal biomass after cultivation. In electroflotation, the hydrophobic algal cells attach to the surface of rising gas bubbles generated by water electrolysis and can be removed as a concentrated froth. For enhanced floatability, the size of microalgae can be increased by flocculation, e.g., with chitosan. Chitosan is a non-toxic, non-contaminating biopolymer that has proven to be a practical flocculant for microalgae. The effectiveness of the flotation process is influenced by numerous variables. At the same time, the mechanisms of the attachment of the algae to the bubbles are not fully understood. Hence, the aim of the presented work is to gain a deeper insight into the processes involved in the electroflotation of microalgae, like the algae-bubble-interaction, using optical measurement methods and machine learning (ML) based image processing. A main focus is on the number and size of bubbles generated by electrolysis, as well as the size of Chlorella vulgaris agglomerates created by flocculation with chitosan. The properties of the bubbles were influenced by changing the electrolysis voltage and evaluated by image processing methods on microscopic images. Using laser diffraction spectroscopy, the influence of different chitosan dosages and flocculation times on the agglomerate size were analyzed. The size distribution is found to depend strongly on the varying biological properties of the microalgal suspension. Nevertheless, some general recommendations for an optimal chitosan concentration range could be deduced. In order to identify conditions promoting a successful attachment of algae to bubbles, an ML based method using series of microscopic images for visualization of the rising bubble and agglomerate paths during bubble-algal interaction was developed. The resu

Hintergrund: Cyclodextrine haben die Fähigkeit, zelluläre Lipide zu mobilisieren und werden daher als neuer Therapieansatz der autosomal rezessiven Niemann-Pick TypC Erkrankung (NPC) im Rahmen von Studien überprüft. NPC ist eine seltene Erkrankung (Inzidenz 1:120.000-1:150.000) des Lipidstoffwechsels, die durch endolysosomale Akkumulation von Cholesterin gekennzeichnet ist. Im Verlauf der Erkrankung kommt es zur progressiven Neurodegeneration. Bei NPC1 Mäusen und Katzen verlangsamte die Therapie mit Kleptose HPB das Fortschreiten der Erkrankung und verlängerte die Lebensdauer, führte aber zu einem signifikanten Hörverlust.Material und Methoden: Im Rahmen der von Vtesse geförderten Phase 2b/3 von VTS-270 (2-Hydroxypropyl-beta-cyclodextrin) wird unter der zweiwöchentlichen intrathekalen Verabreichung von VTS-270 an drei NPC-erkrankten Probanden das Hörvermögen durch eine umfassende Audiometrie einschließlich Reintonaudiometrie, DPOAE-Messung, überschwelliger BERA sowie Sprachaudiometrie verlaufskontrolliert.Ergebnisse: Unter der Therapie mit VTS-270 zeigt sich ein progredienter sensorineuraler Hörverlust ab 2 kHz. Die erhöhten Schwellenwerte gingen mit einer Eliminierung der DPOAE einher. Bei einem Probanden zeigte sich nach der Verabreichung ein akuter pantonaler, hochtonbetonter Hörverlust, der sich nach Therapiepause und Dosisreduzierung im Tieftonbereich wieder regenerierte.Diskussion: Sowohl die Manifestation der NPC-Krankheit als auch die Therapie mit VTS-270 führen zu einem hochfrequenten Hörverlust. Bei NPC-Patienten ist eine retrocochleäre Schwerhörigkeit häufig, die Hörverluste unter der Therapie gehen hingegen mit einer Eliminierung der DPOAE einher. Dies deutet auf einen Funktionsverlust der äußeren Haarzellen, der sich jedoch teilweise regenerierbar zeigt. Die Ergebnisse weisen zudem auf eine individuelle dosisabhängige Schädigung der äußeren Haarzellen.Fazit: VTS-270 wird derzeit in Studien für die Behandlung von NPC-Typ C getestet. Unter der Therapie ze

High Rate Algae Ponds (HRAPs) are a promising technology for the treatment of municipal wastewater in locations with sufficient space and solar radiation. Algae-based processes do not require aeration, and thus have the potential to be less energy-intensive than activated sludge processes.We used a combination of LCA and LCCA analysis to evaluate the sustainability of HRAP systems, using data from the construction and operation of two demonstration-scale systems in Almería and Cádiz, Spain. As a reference for comparison, we used data from an activated sludge-based Sequencing Batch Reactor (SBR) treatment system in operation in Leppersdorf, Germany, which has comparable removal rates for a similar inflow. We focused solely on the actual wastewater treatment aspect of these technologies, excluding sludge treatment from this analysis.Based on our analysis, the current HRAP technology is more energy-efficient than activated sludge-based SBRs and requires only 22% of its electricity consumption. In addition, HRAP is more advantageous both economically (0.18 €/m3 versus 0.26 €/m3) and environmentally, with both lower global warming and eutrophication potentials (146.27 vs. 458.27 × 10−3 kg CO2 equiv./m3; 126.14 vs. 158.01 × 10−6 kg PO4 equiv./m3). However, the Net Environmental Benefit of SBR was slightly more favorable than of HRAP because of the higher removal rate for nutrients of SBR.