Advances in bioelectrochemical technology for enhanced synergistic salt control and decontamination in coastal green infrastructure systems

Objective Coastal green infrastructure systems are widely used in sponge city construction. The soil-plant system, as the core functional unit, bears the key responsibility for salt control and decontamination. However, its plant growth, microbial activity, and decontamination performance are susceptible to soil secondary salinization. Bioelectrochemical technology, specifically microbial electrolysis cells (MEC), shows potential in controlling soil salinization and enhancing pollutant degradation.

Methods This paper systematically reviews the research on MEC-enhanced coastal soil-plant systems for synergistic salt control and pollutant removal, summarizes the salt control and pollutant removal effects of soil-plant systems, and analyzes the influence of MEC on soil-plant systems.

Results The results show that the combined design of subsurface drainage pipes and salt-isolation layers can effectively facilitate salt leaching in coastal green space systems; salt-tolerant plants can also improve soil structure and promote soil desalination, while the soil-plant-rhizosphere microbiome can synergistically achieve high-efficiency pollutant removal. MEC mainly achieves soil desalination by driving salt ion migration via a weak electric field, while also stimulating electroactive microbial metabolism and enhancing plant stress resistance, thereby significantly improving the synergistic salt control and pollutant removal performance of the soil-plant system. However, there remain bottlenecks in MEC-enhanced coastal soil-plant systems, including high electrode material costs, lack of long-term pilot-scale verification, and unclear synergistic mechanisms among bioelectrochemical processes, soil, andplant components.

Conclusion Future efforts should focus on developing low-cost electrode materials, conducting long-term pilot-scale experiments, systematically analyzing the coupled synergistic mechanisms among MEC, soil, and plants, and establishing engineering design parameter systems, so as to advance the engineering application and uptake of bioelectrochemical technology in coastal green infrastructure systems.