Blue energy for sustainable water reclamation in WWTPs

• Published in: Journal of water process engineering 2020-02, Vol.33, p.101020, Article 101020
• Main Authors: Gómez-Coma, L., Ortiz-Martínez, V.M., Fallanza, M., Ortiz, A., Ibañez, R., Ortiz, I.
• Format: Article
• Language: English
• Subjects: Energy sustainability; Reverse electrodialysis; Salinity gradient power; Wastewater reclamation
• ISSN: 2214-7144; 2214-7144
• DOI: 10.1016/j.jwpe.2019.101020

•Novel strategy to promote water reclamation in coastal wastewater treatment plants.•Wastewater reclamation with simultaneous recovery of salinity gradient energy.•Using reclaimed water as feeding stream in reverse electrodialysis stacks.•The pilot run for 480 h with no loss of power performance.•Efficient strategy for fouling prevention and further water reuse. The benefits of wastewater (WW) reclamation to alleviate the stress of freshwater resources are counterbalanced by the required energy demand to drive the treatments. This handicap can be considerably minimized when renewable energy sources are integrated to perform this process, increasing the environmental and energy sustainability of the reclamation process. This work reports the assessment of a new strategy for WW reclamation in shoreline wastewater treatment plants (WWTPs) through the conversion of the salinity gradient energy (SGE) generated in the contact between reclaimed water (RW) and seawater (SW) to electricity by the use of reverse electrodialysis (RED). Secondary effluents from the selected WWTP were further treated by a simple remediation process consisting of coagulation-flocculation and solids removal, ending with a filtration stage; the obtained RW contained 0.008 M NaCl and was used as low concentrated solution in the RED stack; besides, filtered SW with 0.5 M NaCl, was employed as high concentrated solution. The plant run for 480 h, reaching gross power up to 1.43 W/m2 without decay along the operation time indicating that no fouling issues appeared in this time period. This represents a great improvement in comparison to the results published in the literature so far; the slight increase in the salinity of RW still allowed for its further reuse. Thus, a novel and energy sustainable strategy to promote WW reclamation with simultaneous SGE recovery is presented.