Abstract: A pilot test was conducted to explore efficiencies of three chlorophyll-a removing methods to treat aquaculture water, i.e. ozonation alone, suction cavitation-assisted ozonation and extrusion cavitation-assisted ozonation. Results show that after 140 min of exposure to ozone, 3 L•min^-1 in ozone flow rate, and 110 mg•L^-1 in ozone concentration and 12.5 L•min^-1 in inflow rate, chlorophyll-a removal rate in aquiculture water lingered around 62.3% with ozonation alone, 78.8% with suction cavitation-assisted ozonation, and 82.2% with extrusion cavitation-assisted ozonation. Moreover, comparison was also made between the three methods in ozone utilization rate and energy consumption rate. Hydrodynamic (extrusion) cavitation-assisted ozonation reached 94.8% in ozone utilization rate, 47.0% higher than ozonation alone. By comparing chlorophyll-a removal-rate per unit energy consumption, it was found that extrusion cavitation-assisted ozonation and suction cavitation-assisted ozonation was 17.9% and 34.1% higher than ozonation alone.

Key words: hydrodynamic cavitation, ozone, eutrophication, chlorophyll-a