2019-Sustainable Industrial Processing Summit
SIPS2019 Volume 11: New and Advanced Materials, Technologies, and Manufacturing
| Editors: | F. Kongoli, F. Marquis, N. Chikhradze, T. Prikhna |
| Publisher: | Flogen Star OUTREACH |
| Publication Year: | 2019 |
| Pages: | 174 pages |
| ISBN: | 978-1-989820-10-0 |
| ISSN: | 2291-1227 (Metals and Materials Processing in a Clean Environment Series) |
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Comparison of Electrodialysis Operational Modes to Remove Coexisting Ions from a Phosphate Containing Solution at Overlimiting Conditions
Eduardo Henrique Rotta1; Luciano Marder1; Marco Antonio Siqueira Rodrigues2; Andrea Moura Bernardes1; Salatiel Wohlmuth da Silva3;1UFRGS, Porto Alegre, Brazil; 2FEEVALE, Porto Alegre, Brazil; 3UNIVERSIDADE FEDERAL DO RIO GRANDE DO SUL, Porto Alegre, Brazil;
Type of Paper: Regular
Id Paper: 67
Topic: 43
Abstract:
Phosphorus (P) is a main element to all life forms with no synthesizable chemical or technological substitute. The already reported depletion of phosphate rock [1], together with the eutrophication problem caused by excessive loads of phosphate in water bodies [2], encourage the development of technologies that promote the recovery of this nutrient from alternative sources, such as municipal wastewater (MW). One of the most studied techniques to recover phosphate from MW is precipitation/crystallization, but it is limited by the initial nutrient concentration and the presence of coexisting ions [3]. Electrodialysis (ED), a membrane-based process that uses an electric field as the driven force, may be viable to overcome these limitations [4,5]. In this regard, the aim of the present study is to compare an ED system operating on galvanostatic and potentiostatic operational modes to remove/separate coexisting ions, such as sulfate and sodium, from phosphate ions of an already concentrated P-containing solution. Thus, we expect to obtain a solution in the concentrated compartment containing sodium and sulfate ions, and a solution retaining the phosphate ions in the diluted compartment. The experiments were carried out in a 5-compartment ED cell with Chinese heterogeneous ion-exchange membranes alternately arranged. In the potentiostatic operational mode, with an imposed potential value of 34.0 V, it was reported an average percent extraction for sodium, sulfate and phosphate ions of 99.5 %, 93.6 % and 33.8 %, respectively. For the galvanostatic operational mode, with an applied current density of 25.0 mA cm-2 (125 % of the limiting current density), the respectively average percent extraction observed for sodium, sulfate and phosphate ions was 97.7 %, 94.2 % and 18.7 %. It can be noted that both methods of operation presented a similar removal of sodium and sulfate ions, but more phosphate ions are transferred to the concentrated compartment in the potentiostatic mode compared to the galvanostatic one, which is an unwanted behavior. In this bias, it can be concluded that operating the ED system in a constant current density is a more suitable condition to achieve the objective of the study.
Keywords:
Environment; Sustainable development; Water purification;References:
[1] European Commission, The European Critical Raw Materials review, Brussels, 2014.[2] V.H. Smith, G.D. Tilman, J.C. Nekola, Eutrophication: impacts of excess nutrient inputs on freshwater, marine, and terrestrial ecosystems, Environmental Pollution. 100 (1999) 179-196.
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[5] V.V. Nikonenko, A.V. Kovalenko, M.K. Urtenov, N.D. Pismenskaya, J. Han, P. Sistat, G. Pourcelly, Desalination at overlimiting currents: State-of-the-art and perspectives, Desalination. 342 (2014) 85-106. doi:10.1016/j.desal.2014.01.008.