Self-sustainable and Highly Efficient Desalination System based on Microbe-Nanostructure Hybrids
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Water shortages and climate change have brought attention to the global need for seawater desalination and renewable energy production. Currently used seawater desalination processes such as reverse osmosis (RO) and multi-stage flash distillation are energy-intensive processes typically requiring up to ~4.5 kWh/m3 and ~10 kWh/m3 of energy, respectively. Electrodialysis is another approach, however requires the application of a direct potential of up to 10 V to generate sufficient potential difference to drive salt ions out of seawater. In recent years, bioelectrochemical systems (BESs) have been developed for bioelectricity or biohydrogen generation by converting organic compounds in wastewater into electrons through the catalytic activity of electrochemically active microorganisms. Microbial desalination cells (MDCs) are one type of BESs that have great potential for simultaneously achieving seawater desalination with zero-energy consumption, bioelectricity production and wastewater treatment. Electrons and protons generated through organic substrate oxidation via bacterial catalysis create charge differences between anode and cathode chambers, which then attract negatively charged ions (Cl-) and positively charged ions (Na+) from seawater to the anode and cathode chambers, respectively. This process results in seawater desalination without the need for an external energy source, where the degree of desalination is directly proportional to the number of electrons generated and transported by the microbes. Despite the great advantages and the long-term potential of MDCs, the acidification of anode chambers due to proton accumulation and the inefficiency in electron transfer between microbes and anodes, which results in a slow desalination process, currently hampers long-term operation stability and widespread implementation. In addition, the high cost of electrodes due to the platinum catalysis makes the current MDC economically unfavorable..........