Removal of Microcystis aeruginosa using hydrodynamic cavitation in a jet pump cavitation reactor: Considering the mechanical and chemical effects

Hydrodynamic cavitation has recently attracted attention for water treatment, particularly in algal bloom removal. An efficient cavitation generator is crucial for large-scale applications. This study developed an algae removal device based on a jet pump cavitation reactor (JPCR) and a model for hydroxyl radical production in cavitation clouds to evaluate cavitation's mechanical and chemical effects under various operating conditions. Algae removal experiments were conducted to determine the optimal operating conditions. Results show that under critical operating conditions, the JPCR maximizes both mechanical and chemical effects, achieving the highest algae removal efficiency for the given structure. After structural optimization (area ratio m = 1.78, throat-length diameter ratio Lth/Dth = 6 and diffuser angle beta = 16 degrees), the algae removal efficiency reaches a maximum of 39.9 % under critical operating condition(h = 0.322), with energy consumption approximately 18 % of that of ultrasonic cavitation. Furthermore, experimental results after the addition of NaHCO3 to inhibit hydroxyl radicals indicate that algal cell disruption results from the combined mechanical and chemical effects, with the chemical effect contributing approximately 25 %. In conclusion, the optimized JPCR can effectively enhance the cavitation effect and holds great potential for large-scale applications in water treatment.