Integrated treatment of reverse osmosis brines coupling electrocoagulation with advanced oxidation processes

Azerrad, SP; Isaacs, M; Dosoretz, CG

Integrated treatment of reverse osmosis brines coupling electrocoagulation with advanced oxidation processes

Azerrad, SP Isaacs, M Dosoretz, CG

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Publication Type:: Journal Article
Citation:: Chemical Engineering Journal, 2019, 356 pp. 771 - 780
Issue Date:: 2019-01-15

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Field	Value	Language
dc.contributor.author	Azerrad, SP	en_US
dc.contributor.author	Isaacs, M	en_US
dc.contributor.author	Dosoretz, CG https://orcid.org/0000-0002-1759-9203	en_US
dc.date.available	2021-01-15T18:05:50Z
dc.date.issued	2019-01-15	en_US
dc.identifier.citation	Chemical Engineering Journal, 2019, 356 pp. 771 - 780	en_US
dc.identifier.issn	1385-8947	en_US
dc.identifier.uri	http://hdl.handle.net/10453/135537
dc.description.abstract	© 2018 Elsevier B.V. The potential of integrating electrocoagulation (EleC) with two-stage reverse osmosis (RO) to enhance desalination of secondary/tertiary effluents through removal of dissolved organic matter (DOM) and scaling salts from brines was studied. EleC appears advantageous due to the high electrical conductivity of RO brines and low residual ions concentration. EleC was performed in batch mode in a flow-through cell with recirculation through a stirred reservoir at 9.4 mA/cm2 current density. Anode was made of Fe or Al as indicated, and cathode of stainless steel. Chemical coagulation (CC) with FeCl3 was tested as reference. EleC resulted in effective removal of phosphate (>99%), carbonate (88–98%) and DOM (40–50%) at a high Faradaic efficiency (>90%). Fe-EleC resulted less suitable than Al-EleC due to partial Fe(II) oxidation at pH 5.5 required for optimal DOM removal, leaving high Fe content and consequently turbidity in the supernatant, whereas residual Al was negligible. At optimal conditions Al release was 75 mg/L for 1st-stage brines-RO1 (2-fold concentrated) and 300 mg/L for 2nd-stage brines-RO2 (∼8.3-fold concentrated), corresponding to a specific energy consumption of 0.30 and 0.23 [Formula presented], respectively. Similar results were obtained with CC, however, its main disadvantage was the considerable increase of chlorides in the supernatant. Since coagulation removes quenching components from brines, coupling EleC with advanced oxidation processes (AOP), either UVA/TiO2 or UVC/H2O2, was also evaluated for oxidation of model micropollutants from brines prior to discharge. Either EleC or CC in tandem with AOP increased micropollutants oxidation by 3–4 fold compared to raw brines, achieving practically complete transformation.	en_US
dc.relation.ispartof	Chemical Engineering Journal	en_US
dc.relation.isbasedon	10.1016/j.cej.2018.09.068	en_US
dc.subject.classification	Chemical Engineering	en_US
dc.title	Integrated treatment of reverse osmosis brines coupling electrocoagulation with advanced oxidation processes	en_US
dc.type	Journal Article
utslib.citation.volume	356	en_US
utslib.for	0904 Chemical Engineering	en_US
utslib.for	0905 Civil Engineering	en_US
utslib.for	0907 Environmental Engineering	en_US
pubs.embargo.period	Not known	en_US
pubs.organisational-group	/University of Technology Sydney
pubs.organisational-group	/University of Technology Sydney/Faculty of Engineering and Information Technology
pubs.organisational-group	/University of Technology Sydney/Faculty of Engineering and Information Technology/School of Civil and Environmental Engineering
utslib.copyright.status	open_access	*
pubs.publication-status	Published	en_US
pubs.volume	356	en_US

Abstract:

© 2018 Elsevier B.V. The potential of integrating electrocoagulation (EleC) with two-stage reverse osmosis (RO) to enhance desalination of secondary/tertiary effluents through removal of dissolved organic matter (DOM) and scaling salts from brines was studied. EleC appears advantageous due to the high electrical conductivity of RO brines and low residual ions concentration. EleC was performed in batch mode in a flow-through cell with recirculation through a stirred reservoir at 9.4 mA/cm2 current density. Anode was made of Fe or Al as indicated, and cathode of stainless steel. Chemical coagulation (CC) with FeCl3 was tested as reference. EleC resulted in effective removal of phosphate (>99%), carbonate (88–98%) and DOM (40–50%) at a high Faradaic efficiency (>90%). Fe-EleC resulted less suitable than Al-EleC due to partial Fe(II) oxidation at pH 5.5 required for optimal DOM removal, leaving high Fe content and consequently turbidity in the supernatant, whereas residual Al was negligible. At optimal conditions Al release was 75 mg/L for 1st-stage brines-RO1 (2-fold concentrated) and 300 mg/L for 2nd-stage brines-RO2 (∼8.3-fold concentrated), corresponding to a specific energy consumption of 0.30 and 0.23 [Formula presented], respectively. Similar results were obtained with CC, however, its main disadvantage was the considerable increase of chlorides in the supernatant. Since coagulation removes quenching components from brines, coupling EleC with advanced oxidation processes (AOP), either UVA/TiO2 or UVC/H2O2, was also evaluated for oxidation of model micropollutants from brines prior to discharge. Either EleC or CC in tandem with AOP increased micropollutants oxidation by 3–4 fold compared to raw brines, achieving practically complete transformation.

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