Salinity reduction of brackish water using a chemical photosynthesis desalination cell

In this study, a chemical photosynthesis desalination cell (CPDC) was investigated for saltwater desalination. The cell consisted of three main parts: (1) an anodic compartment where the oxidation reaction occurs, releasing electrons, (2) a cathode compartment where the required soluble oxygen is provided by microalgae photosynthesis, and (3) an electrodialysis desalination cell installed between the cathode and anode. In the anode, a novel idea was adopted to shorten the desalination duration and increase the salinity rate using a chemical oxidation reaction in combination with the biocathode. The CPDC contributed to the carbon dioxide biological sequestration (reducing air pollution), produced microalgae biomass as a source of renewable energy and generated electricity. In the investigated CPDC, microalgae were used to supply the required oxygen solution as an electron acceptor. The metal anode-microalgae biocathode battery could provide the required energy for electrodialysis. In addition, some extra electricity was generated with a maximum excess power density of 32.4W/m(3) per volume of the net anodic compartment, 16.2W/m(3) per volume of the net cathodic compartment, and 3.07 W/m(2) of membrane surface area. This study confirms the benefits of microalgae as a sustainable biocathode in microbial desalination cells (MDCs) to supply electron acceptors in an environmental-friendlymanner. Compared to photosynthetic microbial desalination cells (PMDCs), the CPDC decreased the desalination time by a factor of about 4. Besides, the NaCl removal was about 69% for 12 g/L NaCl concentration in the CPDC, higher than other MDCs. In addition, as a new operational factor, the internal resistance variations were determined by electrochemical impedance spectroscopy in different case studies. The results demonstrated for the first time the possibility of applying a new desalination cell (i.e. CPDC) for water desalination and power generation which only uses a source of chemical reaction and microalgae photosynthesis without the need for an external power source. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

The study investigated a chemical photosynthesis desalination cell (CPDC) for saltwater desalination, utilizing microalgae photosynthesis to provide dissolved oxygen and generate electricity. Compared to photosynthetic microbial desalination cells (PMDCs), CPDC showed higher desalination efficiency and reduced desalination time. By utilizing a biocathode, it was possible to generate more electricity and provide a new potential for water desalination and power generation.