Breaking the sequential treatment paradigm: Plasma-assisted electrosorption enables one-step algal cell demolition, P...

Harmful algal blooms (HABs) driven by excess nitrogen and phosphorus threaten water security worldwide. Conventional treatments face challenges in achieving simultaneous algae demolition, phosphorus recovery, and nitrogen stripping, often leading to secondary pollution. This study introduces a novel plasma-electrosorption triplex system (PETS) that enables synergistic, one-step algae demolition, phosphorus recovery, and nitrate removal within an integrated unit without the need for externally supplied chemical additives. The system couples a dielectric barrier discharge (DBD) plasma reactor with pulsed electrosorption using a single power source. Plasma-generated reactive oxygen species (ROS) disrupt algal cells and oxidize organic phosphorus, while triggering an autocatalytic Fe(II/III) cycle for phosphate precipitation. Subsequent pulsed electrosorption achieves selective nitrate capture through modulated electric double layers. Under optimal laboratory conditions using synthetic water, PETS achieved high removal efficiencies of 99.9% for algae, 99.9% for phosphorus, and 85.1% for nitrate. Mechanistic studies revealed that ROS-induced membrane damage and Fe(OH)₃-mediated adsorption are crucial for algal inactivation and phosphorus recovery, while pulsed electric fields enhance ion migration. The system exhibited excellent stability over multiple cycles and in various real water matrices, offering a transformative and sustainable framework for managing eutrophic waters.