Simultaneous desalination and nutrient recovery during municipal wastewater treatment using microbial electrolysis desalination cell

• DOI: 10.1016/j.jclepro.2020.121248
• Publication Date: 2020-03-24T20:10:17Z
• Authors: Jiahuan Li; Rudong Liu; Shan Zhao; Shuguang Wang; Yunkun Wang
• Keywords: 11. Sustainability; 01 natural sciences; 7. Clean energy; 6. Clean water; 0105 earth and related environmental sciences; 12. Responsible consumption

Abstract The removal of organics and saline while simultaneously recovering nutrients in municipal wastewater was achieved in a microbial electrolysis desalination cell (MEDC). System performance in terms of organics removal, desalination, and nitrogen and phosphate recovery was investigated under different ion exchange membrane (IEM) pairs and applied voltages. Compared with single-IEM stack MEDC, the MEDC with multi-IEM pairs proved to be able to perform an effective performance for chemical oxygen demand (COD) removal, desalination, and nutrient recovery. The energy consumption for netrient separation and recovery was 0.12 kWh/m3 with 3-IEM stacks at applied voltage of 2 V. The MEDC system with 3-IEM stacks showed 75.5 ± 1.4% COD removal and 8.5 ± 1.1% Coulombic efficiency. The conductivity in effluent decreased to 545 μS/cm (lower than the single-IEM stack, 934 μS/cm), while conductivity in the product chamber was concentrated to 2160 μS/cm (higher than the single-IEM stack, 998.5 μS/cm). Moreover, the recovery efficiencies of nitrogen and phosphate reached 66 ± 5.3% and 66.7 ± 4.7%, respectively. Furthermore, the CV curve and microbial community structure showed that electrical stimulation increased the abundances of electrogenic bacteria (Rhodocyclaceae and Geobacter), which enhanced COD removal and electron transfer. These results clearly demonstrate that the MEDC is an energy efficient technology for the treatment of municipal wastewater, while simultaneously recovering nitrogen and phosphate resources.