Simultaneous Removal of <i>Microcystis aeruginosa</i> and Sulfamethoxazole Triggered by Acoustic Cavitation Generated Near Nitrogen-Doped Nanodiamond/Cyanobacterial Cell Hybrids

Cyanobacterial algal blooms (cyanoHAB) are toxic, posing severe environmental and health risks. It is also common to find trace amounts of antibiotics in the water, thus posing a dual threat to public health. This study developed a sonosensitive nitrogen-doped nanodiamond (N-ND)/Microcystis aeruginosa hybrid system to simultaneously remove cyanobacterial harmful algal blooms (cyanoHABs) and a typical antibiotic sulfamethoxazole (SMX). Positively charged N-ND formed flocs with negatively charged M. aeruginosa, enhancing localized cavitation under 40 kHz ultrasound. After 30 min of treatment, the system achieved 81.8% algal removal and 60% degradation of 5 mg/L SMX. The localized cavitation near algal cells maximizes radical transfer efficiency, contributing to cell oxidation and SMX degradation. To our knowledge, this is the first demonstration of leveraging cyanoHABs as a biodegradation agent for high-concentration SMX in a sonochemical process. The results offer a dual-functional solution for mitigating cyanoHABs and antibiotic pollution in water, with potential for scalable applications. Life cycle assessment (LCA) showed that the integrated ultrasonic treatment and nitrogen-doped nanodiamond (N-ND) technology have advantages in environmental sustainability, particularly in water conservation. Future research should explore cost-effective and environmentally friendly alternative sonosensitizers to optimize the environmental performance and engineering feasibility of integrated pollution control systems.