Title: Reverse electrodialysis salinity gradient power potential of treated municipal wastewaters used as diluted solution

Authors: Ali Zoungrana; Çağla Aksel; Oruç Kaan Türk; Mehmet Çakmakci

Addresses: Environmental Engineering Department, Yildiz Technical University, 34220 Esenler, Istanbul, Turkey ' Environmental Engineering Department, Yildiz Technical University, 34220 Esenler, Istanbul, Turkey ' Environmental Engineering Department, Yildiz Technical University, 34220 Esenler, Istanbul, Turkey ' Environmental Engineering Department, Yildiz Technical University, 34220 Esenler, Istanbul, Turkey

Abstract: The reverse electrodialysis (RED) process fed with natural solutions was operated for six days and resulted to power densities for the combination ultrafiltration (UF) effluent-seawater, membrane bioreactor (MBR) effluent-seawater, advanced biological treatment (ABT) effluents-seawater around 0.52, 0.50 and 0.48 W.m⁻², respectively, while the synthetic solutions generated 0.57 W.m⁻². No significant difference between the power densities of synthetic and natural solutions was observed, due to their quality. The SEM-EDX analysis showed that Mg²⁺ and Ca²⁺ were present in natural solutions and may have contributed to reducing the power output. The SEM and FTIR results revealed a slight deposition of pollutants on the ions exchange membranes (IEMs) surface, but no fouling, scaling or structural modification was observed. Treated municipal wastewater discharged into seawater are important sources of energy with RED, however, high solution quality together with improved, highly selective and cost-effective IEMs are necessary to enhance and optimise the power output.

Keywords: ions exchange membranes; IEMs; reverse electrodialysis; RED; salinity gradient power; seawater; wastewater.

DOI: 10.1504/IJGW.2021.114350

International Journal of Global Warming, 2021 Vol.23 No.4, pp.463 - 481

Received: 02 May 2020
Accepted: 03 Sep 2020
Published online: 19 Apr 2021 *

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