Eutrophic water purification efficiency using a combination of hydrodynamic cavitation and ozonation on a pilot scale

This paper presents the purification of eutrophic water using a combination of hydrodynamic cavitation (HC) and ozonation (O-3) at a continuous flow of 0.8 m(3) h(-1) on a pilot scale. The maximum removal rate of chlorophyll a using O-3 alone and the HC/O-3 combination was 62.3 and 78.8 %, respectively, under optimal conditions, where the ozone utilization efficiency was 64.5 and 94.8 % and total energy consumption was 8.89 and 8.25 kWh m(-3), respectively. Thus, the removal rate of chlorophyll a and the ozone utilization efficiency were improved by 26.5 % and 46.9 %, respectively, by using the combined technique. Meanwhile, total energy consumption was reduced by 7.2 %. Turbidity linearly decreased with chlorophyll a removal rate, but no linear relationship exists between the removal of COD or UV254 and chlorophyll a. As expected, the suction-cavitation-assisted O-3 exhibited higher energy efficiency than the extrusion-cavitation-assisted O-3 and O-3 alone methods.