Bioelectrochemical desalination and electricity generation in microbial desalination cell with dewatered sludge as fuel

• Simultaneous desalination and dewatered sludge stabilization were achieved.
• Desalination rate for low concentration salt water was more than 40% in 24 h.
• The Pmax of 3.178 W/m3 and open circuit voltage of 1.118 V occurred on 130 d.
• Removal of organic matter was up to 25.71 ± 0.15% after operation for 300 d.

Microbial desalination cells (MDCs) with common liquid anodic substrate exhibit a slow startup and destructive pH drop, and abiotic cathodes have high cost and low sustainability. A biocathode MDC with dewatered sludge as fuel was developed for synergistic desalination, electricity generation and sludge stabilization. Experimental results indicated that the startup period was reduced to 3 d, anodic pH was maintained between 6.6 and 7.6, and high stability was shown under long-term operation (300 d). When initial NaCl concentrations were 5 and 10 g/L, the desalinization rates during stable operation were 46.37 ± 1.14% and 40.74 ± 0.89%, respectively. The maximum power output of 3.178 W/m3 with open circuit voltage (OCV) of 1.118 V was produced on 130 d. After 300 d, 25.71 ± 0.15% of organic matter was removed. These results demonstrated that dewatered sludge was an appropriate anodic substrate to enhance MDC stability for desalination and electricity generation.

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