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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