Numerical Simulation Study on the Stability of Potassium Ion Concentrations at Water Intakes for Seawater Potassium Extraction

Potassium ion concentrations in seawater are the key variables determining the energy consumption and cost of seawater potassium extraction, and are prone to fluctuations induced by runoff into the sea and project drainage. Therefore, ensuring stable potassium ion concentrations in the intake sea area is a fundamental prerequisite for green potassium extraction and cleaner production, supporting process planning, production regulation, cost control and ecological risk prevention. We identified the key drivers of changes in potassium ion concentration at the project water intake for the seawater potassium extraction project in Tianjin Nangang, Bohai Bay. The results show that project drainage has a negligible impact on intake potassium ion concentrations, whereas flood discharge from adjacent rivers during flood seasons is the key factor causing seasonal concentration fluctuations. The exchange of high-potassium-ion seawater from the open sea promotes concentration recovery, with its effect regulated by freshwater input intensity. Based on the findings, we propose targeted optimisation suggestions, providing scientific support for the large-scale green development and utilisation of marine potassium resources.