Simultaneous chloride removal and resource recovery from sea sand: A high-efficiency and low-energy process using microbial electrolysis desalination and chemical-production cell

Efficient and eco-friendly desalination of sea sand is crucial for the sustainable utilization of marine resources and environmental conservation. This study aims to demonstrate the feasibility of simultaneously desalinating sea sand and recovering resources through a combined treatment process comprising alkali precipitation and microbial electrolysis desalination and chemical-production cell (MEDCC). The pretreatment of sea sand with alkali addition effectively removed Ca2+ and Mg2+, thereby mitigating membrane scaling and boosting electricity generation in the MEDCC process. Using a pretreated mixture of water and sand as feed, the MEDCC achieved a maximum current density of 11.57 +/- 0.45 A/m2, which was 2.3-fold higher compared to nonpretreated feedstock. The final chloride removal efficiency from sea sand achieved 92 +/- 1 %. Additionally, all three effluents (fresh water, acid, and alkali) can be reused within the process. During the treatment process, 51 +/- 1 % of the energy was provided by biomass-derived electricity, highlighting substantial energy savings. Hence, the MEDCC holds significant potential for sea sand desalination with resource recovery.