Search Results (5)

Efficient solid–liquid separation is crucial in industries like mining, but traditional chamber filter presses depend heavily on manual monitoring, leading to inefficiencies, downtime, and resource wastage. This paper introduces a machine learning-powered digital twin framework to improve the operational flexibility and predictive control of a traditional chamber filter press. A key challenge addressed is the degradation of the filter medium due to repeated cycles and clogging, which reduces filtration efficiency. To solve this, a neural network-based predictive model was developed to forecast operational parameters, such as pressure and flow rates, under various conditions. This predictive capability allows for optimized filtration cycles, reduced downtime, and improved process efficiency. Additionally, the model predicts the filter medium’s lifespan, aiding in maintenance planning and resource sustainability. The digital twin framework enables seamless data exchange between filter press sensors and the predictive model, ensuring continuous updates to the training data and enhancing accuracy over time. Two neural network architectures, feedforward and recurrent, were evaluated. The recurrent neural network outperformed the feedforward model, demonstrating superior generalization. It achieved a relative $L^2$-norm error of $5\%$ for pressure and $9.3\%$ for flow rate prediction on partially known data. For completely unknown data, the relative errors were $18.4\%$ and $15.4\%$, respectively. Qualitative analysis showed strong alignment between predicted and measured data, with deviations within a confidence band of $8.2\%$ for pressure and $4.8\%$ for flow rate predictions. This work contributes an accurate predictive model, a new approach to predicting filter medium cycle impacts, and a real-time interface for model updates, ensuring adaptability to changing operational conditions. Full article

Short-chain fatty acids (SCFAs) are valuable metabolic intermediates that are produced during dark fermentation of sludge, which, when capitalized on, can be used as chemical precursors for biotechnological applications. However, high concentrations of solids with SCFAs in hydrolyzed sludge can be highly detrimental to downstream recovery processes. This pilot-scale study addresses this limitation and explores the recovery of SCFAs from primary sludge into a particle-free permeate through a combination of chamber filter-press (material: polyester; mesh size: 100 µm) and cross-flow microfiltration (material: α-Al₂O₃; pore size: 0.2 µm; cross-flow velocity: 3 m∙s⁻¹; pressure = 2.2 bars). Firstly, primary sludge underwent dark fermentation yielding a hydrolyzate with a significant concentration of SCFAs along with total solids (TS) concentration in the range of 20 to 30 g∙L⁻¹. The hydrolyzate was conditioned with hydroxypropyl trimethyl ammonium starch (HPAS), and then dewatered using a filter press, reducing TS by at least 60%, resulting in a filtrate with a suspended solids concentration ranging from 100 to 1300 mg∙L⁻¹. Despite the lower suspended solids concentration, the microfiltration membrane underwent severe fouling due to HPAS’s electrostatic interaction. Two methods were optimized for microfiltration: (1) increased backwashing frequency to sustain a permeate flux of 20 L∙m⁻²∙h⁻¹ (LMH), and (2) surface charge modification to maintain the flux between 70 and 80 LMH. With backwashing, microfiltration can filter around 900 L∙m_eff⁻² (without chemical cleaning), with the flux between 50 and 60 LMH under semi-continuous operation. Evaluating the particle-free permeate obtained from the treatment chain, around 4 gC_SCFAs∙capita⁻¹∙d⁻¹ can be recovered from primary sludge with a purity of 0.85 to 0.97 C_SCFAs∙DOC⁻¹. Full article

Currently, the storage of ore processing residues is a major challenge in the mining industry. These tailings are increasingly filtered in advance of disposal using filter presses to make storage safer and to recover water effectively. However, the falling of the detached filter cakes between the individual filtration cycles results in the abrasive wear of the filter cloths at specific points of the chamber geometry and is a main reason for the necessity of a regular replacement. Improved filter media selection through abrasion testing replicating this specific load case increases plant economics by reducing the risk of unplanned downtimes. Therefore, this article explains a test procedure adapted to the direction-specific wear. A brush apparatus is presented, which abrasively loads filter fabrics stretched over an exchangeable edge geometry uniaxially in one direction. The effects of important apparatus setting parameters (sample clamping torque, brush overlap, and brush speed) are shown. Furthermore, the resistances of three different filter media typical for tailings filtration were compared and different edge geometries investigated. Thereby, significant differences were found with regard to filter media type, filter media material, and edge geometry. Depending on the edge geometry used, the polypropylene fabric withstands a load amount by a factor of 3.3 to 8.9 higher than the nonwoven polypropylene, the nylon fabric withstands a load amount by a factor of 3.6 to 5.3 higher than the polypropylene fabric and the nylon cloth withstands a load amount by a factor of 16.1 to 31.8 higher than the nonwoven polypropylene. Full article

Unit operations (UO) are mostly used in non-ferrous extractive metallurgy (NFEM) and usually separated into three categories: (1) hydrometallurgy (leaching under atmospheric and high pressure conditions, mixing of solution with gas and mechanical parts, neutralization of solution, precipitation and cementation of metals from solution aiming purification, and compound productions during crystallization), (2) pyrometallurgy (roasting, smelting, refining), and (3) electrometallurgy (aqueous electrolysis and molten salt electrolysis). The high demand for critical metals, such as rare earth elements (REE), indium, scandium, and gallium raises the need for an advance in understanding of the UO in NFEM. The aimed metal is first transferred from ores and concentrates to a solution using a selective dissolution (leaching or dry digestion) under an atmospheric pressure below 1 bar at 100 °C in an agitating glass reactor and under a high pressure (40–50 bar) at high temperatures (below 270 °C) in an autoclave and tubular reactor. The purification of the obtained solution was performed using neutralization agents such as sodium hydroxide and calcium carbonate or more selective precipitation agents such as sodium carbonate and oxalic acid. The separation of metals is possible using liquid (water solution)/liquid (organic phase) extraction (solvent extraction (SX) in mixer-settler) and solid-liquid filtration in chamber filter-press under pressure until 5 bar. Crystallization is the process by which a metallic compound is converted from a liquid into a crystalline state via a supersaturated solution. The final step is metal production using different methods (aqueous electrolysis for basic metals such as copper, zinc, silver, and molten salt electrolysis for REE and aluminum). Advanced processes, such as ultrasonic spray pyrolysis, microwave assisted leaching, and can be combined with reduction processes in order to produce metallic powders. Some preparation for the leaching process is performed via a roasting process in a rotary furnace, where the sulfidic ore was first oxidized in an oxidic form which is a suitable for the metal transfer to water solution. UO in extractive metallurgy of REE can be successfully used not only for the metal wining from primary materials, but also for its recovery from secondary materials. Full article

Although immunomagnetic separation is a useful sample pretreatment method that can be used to separate target pathogens from a raw sample, it is challenging to remove unbound free magnetic nanoparticles (MNPs) for colorimetric detection of target pathogens. Here, size-based filtration was exploited for the rapid on-site detection of pathogens separated by immunomagnetic separation in order to remove unbound free MNPs using a finger-powered microfluidic device. A membrane filter and an absorbent pad were integrated into the device and a mixture of unbound free MNPs and MNP-bound Escherichia coli (E. coli) O157:H7 was dispensed over the membrane filter by pressing and releasing the pressure chamber. A colorimetric signal was generated by MNP-bound E. coli O157:H7 while unbound free MNPs were washed out by the absorbent. Furthermore, the colorimetric signals can be amplified using a gold enhancer solution when gold-coated MNPs were used instead of MNPs. As a result, 10² CFU/mL E. coli O157:H7 could be detected by the enhanced colorimetric signal on a proposed device. Full article