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Assisted-Reverse Electrodialysis for the remineralization of RO permeate through recovery of minerals from brines
No full textAssisted-Reverse Electrodialysis: a novel method to remineralize surface RO permeate by recovering minerals from its brine
No full textSurface water RO permeate remineralization through minerals recovery from brines
No full textAssisted-Reverse Electrodialysis (A-RED) technology was applied following reverse osmosis (RO) of a surface water resource in order to recover minerals from its brine and directly remineralize the RO unit's permeate. Four different sets of cation/anion exchange membranes were benchmarked using single- and mixed-salts synthetic solutions as well as real brine and permeate streams produced from three-stage reverse osmosis applied to Seine River water. The process, operating under equal permeate and brine channel flows (2 cm/s velocities) and applied voltage varying from 0 to 10 V, showed viable remineralization results. Optimal recovery at 10 V applied allowed increasing permeate mineral content from 20 mg/L CaCO3 up to values of 553 mg/L CaCO3 and from 100 μS/cm up to 1284 μS/cm for hardness and conductivity respectively. Tests using spiked micropollutants showed very low levels of micropollutant passage with over 98% rejection for 15 out of 18 compounds tested while natural organic matter (NOM) breakthrough was 2% on average (0.2 mg C/L)
TRANSPORT OF IONS IN ASSISTED-REVERSE ELECTRODIALYSIS FOR SURFACE WATER REVERSE OSMOSIS PERMEATE REMINERALIZATION
No full textValorization of surface-water RO brines via Assisted-Reverse Electrodialysis for minerals recovery: performance analysis and scale-up perspectives
No full textReverse Osmosis (RO) plays a key role in seawater and brackish water desalination to fulfill the growing demand for fresh water. In recent years, RO has also been more and more adopted for the treatment and potabilization of surface waters, leading to two main problems: (i) the depletion in minerals of the product water, making it aggressive and unsuitable for drinking purposes and (ii) the production of a concentrated brine requiring proper disposal. Permeate remineralization post-treatments include pH adjustment and addition of minerals, such as bicarbonates, calcium and magnesium, which are essential for human health and required to meet drinking water guidelines. However, such solutions are exposed to critical issues related to supply, cost as well as extraction and transportation of chemicals.
In this work, we investigate, via modelling tools, the use of Assisted-Reverse Electrodialysis (A-RED) to remineralize a surface water RO permeate stream by recovering minerals from its corresponding brine itself. This concept (patent pending [1]) was explored at the bench scale [2] and the subsequent experimental data used to validate the multi-scale model used in this study.
The validated model was implemented to perform a process parametric analysis aiming at the design and optimization of a pilot-scale plant. Sensitivity analysis was performed considering the use of different stacks in series and hybrid configurations, including feed & bleed loops for one or both compartments and permeate by-pass.
Moreover, the use of simplified techno-economic analysis tools allowed to identify the most promising configurations, which reduce the main cost items relevant to the industrial scale-up of the technology. More than 150 simulations were performed to compare different scenarios on the basis of the main performance parameters characterizing electro-membrane processes such as energy consumption, apparent flux and remineralization capacity. Results have shown that energy consumption can be reduced to less than 0.1 kWh/kg of salt transported to the permeate, in the case of permeate flow rates up to ~2 m3/h, while apparent fluxes can rise to ~170 l/(h*m2) for larger bypass flow rates, resulting in lower capital and overall costs
A new process for resourse recovery from surface water RO brine from permeate remineralization
No full textLow-Pressure Reverse Osmosis (LPRO) membranes could be valuable alternatives to conventional surface water potabilization processes [1] thanks to a combined ability to: remove micropollutants, soften, disinfect and remove organic substances. However, these processes produce an aggressive permeate and a concentrated brine with discharge constraints [2]. Assisted Reverse Electrodialysis (A-RED, [3]) was tested for LPRO permeate remineralization by recovery of target minerals from the corresponding LPRO brine while maintaining the product water’s integrity with respect to the organic compounds present in the concentrate.
Bench-scale experiments were carried out with SUEZ-WTS membranes (CR67T-AR204T), operating under equal permeate and brine flows (2 cm/s velocities). The process was first tested using synthetic salt solutions, with varying applied voltage, permeate and brine inlet conductivity and brine composition to study the selective transport of individual species. Tests were then performed with Seine River LPRO brine spiked with 17 micropollutants to investigate membrane retention capacity.
Results showed that ion transport numbers and permselectivity were weakly influenced by inlet solution conductivity and applied current/voltage, while permselectivity was mainly influenced by brine composition. High passage of salts was observed, allowing for a significant increase of permeate mineral content from ≈20 mg/L CaCO3 up to ≈490 mg/L CaCO3 and from ≈120 μS/cm up to 1284 μS/cm for hardness and conductivity, respectively. Spiked brine runs highlighted low micropollutant passage with over 98% rejection for 15 out of 17 compounds while natural organic matter breakthrough averaged 2% (0.2 mg C/L).
Following these positive results a pilot unit was set-up with two 70 cell-pair stacks in series, fed with LPRO permeate and brine at nominal flow rates of 3.6 m3/h. Preliminary results have confirmed process feasibility while long-term performance stability evaluation is ongoing. Overall, results of this study highlighted the viability of the proposed process for LPRO permeate remineralization to target potable levels
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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