Simultaneous ammonium and phosphate recovery and stabilization from urban sewage sludge anaerobic digestates using reactive sorbents

The use of low-cost inorganic sorbents as a new sustainable strategy to enhance the valorization of nutrients (N-P-K), from the urban water cycle (e.g., side streams from sewage sludge anaerobic digestion), in agriculture applications is presented. The simultaneous recovery and stabilization of ammonium and phosphate by using a mixture of two reactive sorbents (Na and K zeolites and magnesium oxide) was evaluated. The nutrients stabilization process, favoured at alkaline pH values, is carried out by a) the precipitation of phosphate ions with magnesium and/or ammonium ions and b) the sorption of ammonium by Na- and K-zeolites. MgO(s) promoted the stabilization of phosphate as bobierrite (Mg3(PO4)2(s)) or struvite (MgNH4PO4(s)) depending on the applied dose. Doses with the stoichiometric molar ratio of Mg/P promote the formation of bobierrite, while molar ratios higher than 3 favour the formation of struvite. Na zeolites (NaP1-NA, NaP1-IQE) demonstrated efficiency on ammonium stabilization between 60 ± 2 (for 15 gZ/L) to 90 ± 3% (for 50 gZ/L). The ammonium recovery efficiency is limited by the zeolite sorption capacity. If the target of the fertilizing criteria should include K, then the use of a K-zeolite (e.g., 5AH-IQE) provides a good solution. The optimum pH for the precipitation of struvite and bobierrite is 9.5 and the optimum pH for ammonium removal is between 4 and 8.5. N is present in higher concentrations (up 0.7–1 g NH4+/L) when pH is ranged between 8.2 and 8.6. The ammonium recovery ratios were better than those previously reported using only magnesium oxide or even a more expensive reagent as newberrite (MgHPO4(s)). The recovery mechanisms described generate low-solubility stabilized nutrients forms that potentially can be applied as slow-release fertilizers in agriculture. Thus, the use in agriculture of blends of digested sludge with low-solubility stabilized nutrients forms will improve soils quality properties in terms of organic matter and nutrients availability.Peer ReviewedPostprint (author's final draft

Valorization of ammonia concentrates from treated urban wastewater using liquid–liquid membrane contactors

The removal of ammonium from tertiary effluents by zeolites generates basic ammonia concentrates (up to 1–3 gNH3/L in 1–2 g NaOH/L). This study evaluates the use of hollow fibre liquid–liquid membrane contactors (HFMCs) as a concentration and purification step for ammonia effluents to produce NH4NO3 and (NH4)2(HPO4) solutions for potential use as liquid fertilizers. The influence of various operational parameters (i.e., flow rate, initial ammonia concentration and stripping acid concentration) was investigated using a closed-loop setup. Due to the high basicity of the ammonia feed streams (pH > 12), the mass transport process was primarily controlled by the free acid concentration in the stripping phase (e.g., HNO3 and H3PO4). A mass transport algorithm to predict the pH of the stripping stream was developed to describe the contactor performance, predict the requirements of the free acid concentration in the stripping phase and optimize the ammonia recovery. Therefore, the closed-loop configuration allowed for ammonia recovery ratios higher than 98% when the required free acid concentration of the stripping phase was maintained. The exhausted NH3/NaOH streams after NH3 removal can be re-used for regeneration of the ammonium-exhausted zeolite filters.Postprint (author's final draft

Ammonium removal by liquid–liquid membrane contactors in water purification process for hydrogen production

© 2014 Balaban Desalination Publications. All rights reserved. In this work, a liquid–liquid membrane contactor (LLMC) was evaluated to remove ammonia traces from water used for hydrogen production by electrolysis. Three operational parameters were evaluated: the feed flow rate, the initial ammonia concentration in the water stream, and the pH of solution. Synthetic aqueous solutions with ammonium concentration of 5–25 mg L-1 and a sulfuric acid solution (pH 2) were supplied to the LLMC in countercurrent and open-loop configuration with flow rates between 2.72 × 10-6 and 22.6 × 10-6 m3 s-1 and the pH values of the solution with ammonium between 8 and 11. A 2D numerical model was developed considering advection–diffusion equation inside a single fiber of the lumen with fully developed laminar flow and liquid–gas equilibrium in the membrane–solution interface. Predictions of the model were then validated against experimental data, which were found to be in good agreement. According to both, experimental data and numerical predictions, the hollow-fiber membrane contactor technology is a suitable alternative to remove ammonium from water and to feed the membrane distillation unit in order to fulfill water quality requirements for electrolysis-based hydrogen production.Peer ReviewedPostprint (author's final draft

Prepolarized MRI of Hard Tissues and Solid-State Matter

[EN] Prepolarized MRI (PMRI) is a long-established technique conceived to counteract the loss in signal-to-noise ratio (SNR) inherent to low-field MRI systems. When it comes to hard biological tissues and solid-state matter, PMRI is severely restricted by their ultra-short characteristic relaxation times. Here we demonstrate that efficient hard-tissue prepolarization is within reach with a special-purpose 0.26 T scanner designed for ex vivo dental MRI and equipped with suitable high-power electronics. We have characterized the performance of a 0.5 T prepolarizer module, which can be switched on and off in 200 mu s. To this end, we have used resin, dental and bone samples, all with T1$${\mathbf{T}}_{\mathbf{1}}$$ times of the order of 20 ms at our field strength. The measured SNR enhancement is in good agreement with a simple theoretical model, and deviations in extreme regimes can be attributed to mechanical vibrations due to the magnetic interaction between the prepolarization and main magnets.Agencia Valenciana de la Innovaci~o; European Regional Development Fund; Ministerio de Ciencia e Innovacion; This work was supported by the Ministerio de Ciencia e Innovaci~on of Spain through research grant PID2019-111436RBC21. Action co-financed by the European Union through the Programa Operativo del Fondo Europeo de Desarrollo Regional (FEDER) of the Comunitat Valenciana 2014-2020 (IDIFEDER/2018/022). JMG and JB acknowledge support from the Innodocto program of the Agencia Valenciana de la Innovacion (INNTA3/2020/22 and INNTA3/2021/17); Ministerio de Ciencia e Innovaci~on of Spain, Grant/Award Number: PID2019-111436RB-C21; Programa Operativo del Fondo Europeo de Desarrollo Regional (FEDER) of the Comunitat Valenciana, Grant/Award Number: IDIFEDER/2018/022; Innodocto program of the Agencia Valenciana de la Innovacion, Grant/Award Numbers: INNTA3/2020/22, INNTA3/2021/17Borreguero-Morata, J.; González Hernández, JM.; Pallás Lodeiro, E.; Rigla, JP.; Algarín-Guisado, JM.; Bosch-Esteve, R.; Galve, F.... (2022). Prepolarized MRI of Hard Tissues and Solid-State Matter. NMR in Biomedicine. 35(8):1-10. https://doi.org/10.1002/nbm.473711035

Simultaneous imaging of hard and soft biological tissues in a low-field dental MRI scanner

[EN] Magnetic Resonance Imaging (MRI) of hard biological tissues is challenging due to the fleeting lifetime and low strength of their response to resonant stimuli, especially at low magnetic fields. Consequently, the impact of MRI on some medical applications, such as dentistry, continues to be limited. Here, we present three-dimensional reconstructions of ex-vivo human teeth, as well as a rabbit head and part of a cow femur, all obtained at a field strength of 260 mT. These images are the first featuring soft and hard tissues simultaneously at sub-Tesla fields, and they have been acquired in a home-made, special-purpose, pre-medical MRI scanner designed with the goal of demonstrating dental imaging at low field settings. We encode spatial information with two pulse sequences: Pointwise-Encoding Time reduction with Radial Acquisition and a new sequence we have called Double Radial Non-Stop Spin Echo, which we find to perform better than the former. For image reconstruction we employ Algebraic Reconstruction Techniques (ART) as well as standard Fourier methods. An analysis of the resulting images shows that ART reconstructions exhibit a higher signal-to-noise ratio with a more homogeneous noise distribution.We thank anonymous donors for their tooth samples, Andrew Webb and Thomas O'Reilly (LUMC) for discussions on hardware and pulse sequences, and Antonio Tristan (UVa) for information on reconstruction techniques. This work was supported by the European Commission under Grants 737180 (FET-OPEN: HISTO-MRI) and 481 (ATTRACT: DentMRI). Action co-financed by the European Union through the Programa Operativo del Fondo Europeo de Desarrollo Regional (FEDER) of the Comunitat Valenciana 2014-2020 (IDIFEDER/2018/022). Santiago Aja-Fernandez acknowledges Ministerio de Ciencia e Innovacion of Spain for research grant RTI2018-094569-B-I00.Algarín-Guisado, JM.; Díaz-Caballero, E.; Borreguero-Morata, J.; Galve, F.; Grau-Ruiz, D.; Rigla, JP.; Bosch-Esteve, R.... (2020). Simultaneous imaging of hard and soft biological tissues in a low-field dental MRI scanner. Scientific Reports. 10(1):1-14. https://doi.org/10.1038/s41598-020-78456-2S114101Haacke, E. M. et al. Magnetic Resonance Imaging: Physical Principles and Sequence Design Vol. 82 (Wiley-liss, New York, 1999).Bercovich, E. & Javitt, M. C. Medical imaging: from roentgen to the digital revolution, and beyond. Rambam Maimonides Med. J. 9, e0034. https://doi.org/10.5041/rmmj.10355 (2018).Mastrogiacomo, S., Dou, W., Jansen, J. A. & Walboomers, X. F. Magnetic resonance imaging of hard tissues and hard tissue engineered bio-substitutes. Mol. Imag. Biol. 21, 1003–1019. https://doi.org/10.1007/s11307-019-01345-2 (2019).Duer, M. J. 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Imaging 49, 1528–1542. https://doi.org/10.1002/jmri.26637 (2019).Sarracanie, M. et al. Low-cost high-performance MRI. Sci. Rep. 5, 15177. https://doi.org/10.1038/srep15177 (2015).Weiger, M. et al. High-resolution ZTE imaging of human teeth. NMR Biomed. 25, 1144–1151. https://doi.org/10.5041/rmmj.103552 (2012).Grodzki, D. M., Jakob, P. M. & Heismann, B. Ultrashort echo time imaging using pointwise encoding time reduction with radial acquisition (PETRA). Magn. Reson. Med. 67, 510–518. https://doi.org/10.5041/rmmj.103553 (2012).Kaczmarz, S. Angenäherte auflösung von systemen linearer gleichungen. Bull. Int. Acad. Pol. Sci. Let., Cl. Sci. Math. Nat. 35, 355–357 (1937).Gordon, R., Bender, R. & Herman, G. T. Algebraic reconstruction techniques (ART) for three-dimensional electron microscopy and X-ray photography. J. Theor. Biol. 29, 471–481. https://doi.org/10.1016/0022-5193(70)90109-8 (1970).Gower, R. M. & Richtarik, P. Randomized iterative methods for linear systems. SIAM J. Matrix Anal. Appl.36, 1660–1690. 10.1137/15M1025487 (2015). arXiv:1506.03296.Ludwig, U. et al. Dental MRI using wireless intraoral coils. Sci. Rep.6, https://doi.org/10.1038/srep23301 (2016).Maggioni, M., Katkovnik, V., Egiazarian, K. & Foi, A. Nonlocal transform-domain filter for volumetric data denoising and reconstruction. IEEE Trans. Image Process. 22, 119–133. https://doi.org/10.5041/rmmj.103555 (2013).Weiger, M. & Pruessmann, K. P. Short-t2 mri: principles and recent advances. Prog. Nucl. Magn. Reson. Spectrosc. 114–115, 237–270 (2019).Jang, H., Wiens, C. N. & McMillan, A. B. Ramped hybrid encoding for improved ultrashort echo time imaging. Magn. Resonance Med. 76, 814–825 (2016).Wu, Y. et al. Water- and fat-suppressed proton projection mri (waspi) of rat femur bone. Magn. Reson. Med. 57, 554–567 (2007).Carr, H. Y. Steady-state free precession in nuclear magnetic resonance. Phys. Rev. 112, 1693–1701. https://doi.org/10.5041/rmmj.103556 (1958).Waugh, J. S., Huber, L. M. & Haeberlen, U. Approach to high-resolution NMR in solids. Phys. Rev. Lett. 20, 180–182. https://doi.org/10.5041/rmmj.103557 (1968).Waeber, A. M. et al. Pulse control protocols for preserving coherence in dipolar-coupled nuclear spin baths. Nat. Commun. 10, 1–9. https://doi.org/10.1038/s41467-019-11160-6 (2019).Frey, M. A. et al. Phosphorus-31 MRI of hard and soft solids using quadratic echo line-narrowing. Proc. Natl. Acad. Sci. U.S.A. 109, 5190–5195. https://doi.org/10.1073/pnas.1117293109 (2012).Galve, F., Alonso, J., Algarín, J. M. & Benlloch, J. M. Magnetic resonance imaging method with zero echo time and slice selection. ESP202030504 (2020).Cooley, C. Z. et al. A portable brain mri scanner for underserved settings and point-of-care imaging. arXiv2004.13183 (2020).Hills, B. P. & Clark, C. J. Quality Assessment of Horticultural Products by NMRhttps://doi.org/10.1016/S0066-4103(03)50002-3 (2003).Somers, A. E., Bastow, T. J., Burgar, M. I., Forsyth, M. & Hill, A. J. 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Improving the Response of Accelerometers for Automotive Applications by Using LMS Adaptive Filters

In this paper, the least-mean-squares (LMS) algorithm was used to eliminate noise corrupting the important information coming from a piezoresisitive accelerometer for automotive applications. This kind of accelerometer is designed to be easily mounted in hard to reach places on vehicles under test, and they usually feature ranges from 50 to 2,000 g (where is the gravitational acceleration, 9.81 m/s2) and frequency responses to 3,000 Hz or higher, with DC response, durable cables, reliable performance and relatively low cost. However, here we show that the response of the sensor under test had a lot of noise and we carried out the signal processing stage by using both conventional and optimal adaptive filtering. Usually, designers have to build their specific analog and digital signal processing circuits, and this fact increases considerably the cost of the entire sensor system and the results are not always satisfactory, because the relevant signal is sometimes buried in a broad-band noise background where the unwanted information and the relevant signal sometimes share a very similar frequency band. Thus, in order to deal with this problem, here we used the LMS adaptive filtering algorithm and compare it with others based on the kind of filters that are typically used for automotive applications. The experimental results are satisfactory

Estudio comparativo del método de los elementos finitos y de la norma VDI 2230 en el cálculo de uniones atornilladas de uso de la industria ferroviaria

Consulta en la Biblioteca ETSI Industriales (Riunet)[ES] Este proyecto ha surgido realizando las prácticas en una empresa del sector ferroviario en la cual se ha cuestionado la utilización de dos programas de diseño del ámbito ingenieri, KISSsoft y Ansys 15. El objetivo es cuantificar las principales diferencias mediante el estudio de las de uniones atornilladas entre la norma VDI 2230 y la teoría de los elementos finitos, de las cuales hablaremos más tarde. El estudio de la norma se hará mediante el programa KISSsoft, herramienta que contiene los cálculos de la norma de uniones atornillada con sus principales fórmulas, y la comprobación mediante elementos finitos con la herramienta Ansys 15, programa puntero en el sector que calcula cualquier tipo de geometría aplicando la teoría de elementos finitos.Pallás Lodeiro, E. (2016). Estudio comparativo del método de los elementos finitos y de la norma VDI 2230 en el cálculo de uniones atornilladas de uso de la industria ferroviaria. http://hdl.handle.net/10251/69777.Archivo delegad

Rejection of ammonium and nitrate from sodium chloride solutions by nanofiltration: Effect of dominant-salt concentration on the trace-ion rejection

In this work, the rejection of two ions associated with fertilizer pollution of ground water (NH4+ and NO3-) by a polyamide nanofiltration (NF270) membrane was studied. Sodium chloride was selected as the dominant salt and the effect of its concentration on the NH4+ and NO3- rejections was evaluated. Filtration experiments were carried out in a cross-flow setup with a rectangular spacer-filled feed channel. The solution-diffusion-electro-migration-film model (SDEFM), previously developed to model the pressure-driven trans-membrane transfer of electrolyte mixtures consisting of a single dominant salt and (any number of) trace ions, was used to obtain membrane ion permeance from the experimental data. In this way, the membrane permeances with respect to single ions (Na+, Cl-, NH4+, NO3-) were obtained for various concentrations of both dominant (0.05 to 0.3 M NaCl) and trace salts (0.001 to 0.003 M NH4Cl/NaNO3). It was observed that when the dominant salt concentration increased, the rejections of dominant salt and trace ions decreased, whereas the membrane permeances to ions increased. This information can be useful for developing design tools for nanofiltration of mixed electrolyte solutions in water-treatment applications.Peer ReviewedPostprint (author's final draft

Ammonia removal from water by liquid-liquid membrane contactor under closed loop regime

Ammonia separation from water by a membrane contactor was simulated on transient state and compared with experimental data. Aqueous low concentrated solution of ammonium with high pH has been pumped inside a hydrophobic hollow fiber (lumen), sulfuric acid solution in the outside part and the feeding solutions are in closed loop configuration. In order to simulate the separation process, the equations were developed considering radial and axial diffusion and convection in the lumen with a well-developed parabolic velocity profile. The model proposed shows minimal deviations when is compared against experimental data. This study shows that the most important parameters to control during the operation are the flow rate and the pH, mainly the last one, due to high dependence in chemical equilibrium of ammonium reaction to ammonia.Peer Reviewe

Rejection of ammonium and nitrate from sodium chloride solutions by nanofiltration: Effect of dominant-salt concentration on the trace-ion rejection

In this work, the rejection of two ions associated with fertilizer pollution of ground water (NH4+ and NO3-) by a polyamide nanofiltration (NF270) membrane was studied. Sodium chloride was selected as the dominant salt and the effect of its concentration on the NH4+ and NO3- rejections was evaluated. Filtration experiments were carried out in a cross-flow setup with a rectangular spacer-filled feed channel. The solution-diffusion-electro-migration-film model (SDEFM), previously developed to model the pressure-driven trans-membrane transfer of electrolyte mixtures consisting of a single dominant salt and (any number of) trace ions, was used to obtain membrane ion permeance from the experimental data. In this way, the membrane permeances with respect to single ions (Na+, Cl-, NH4+, NO3-) were obtained for various concentrations of both dominant (0.05 to 0.3 M NaCl) and trace salts (0.001 to 0.003 M NH4Cl/NaNO3). It was observed that when the dominant salt concentration increased, the rejections of dominant salt and trace ions decreased, whereas the membrane permeances to ions increased. This information can be useful for developing design tools for nanofiltration of mixed electrolyte solutions in water-treatment applications.Peer Reviewe