The objective of
this study was to reproduce a comprehensive catalogue of the effect that
ultrasound has across all problematic blooming algal species. A range of algal
species were tested including cyanobacteria species Microcystis aeruginosa
and Aphanziomenon flos-aquae, a green alga Scenedesmus subspicatus and
a wild type diatom Melosira sp. The experiments were performed using
laboratory scale ultrasonic equipment covering frequencies between 20 kHz
and 1.15 MHz, and power ranges of 200-420Watts.
Key results have demonstrated a relationship between energy input per unit
volume and cell removal efficiency. For instance Microcystis aeruginosa
needed 100kWh/m<sup>3</sup> at a frequency of 20-30 KHz to remove 60% of cells, after
which no bloom recovery can occur. Aphanziomenon fq. required lower
energy only 20-30kWh/m<sup>3</sup> but a higher frequency of 1144kHz for 100% cell
removal. Coupling the removal data and Chlorophyll fluorescence and TEM
imaging has enabled the impact of ultrasound and algal physiology to be
established. When the energy input increases beyond 278kWh/M<sup>3</sup> critical cell
rupture is reached producing removal rates of 60% for Microcystis aeruginosa
below this energy level limited removal is observed which is thought to be due
to the inability of cell rupture to occur. The paper concludes by comparing
ultrasound to other algal removal technologies to establish under which
situation it becomes the most appropriate technology selection. Includes 21 references, figures.
| Edition : | Vol. - No. |
| File Size : | 1
file
, 740 KB |
| Note : | This product is unavailable in Ukraine, Russia, Belarus |
| Number of Pages : | 9 |
| Published : | 11/01/2008 |
