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The objective ofthis study was to reproduce a comprehensive catalogue of the effect thatultrasound has across all problematic blooming algal species. A range of algalspecies were tested including cyanobacteria species Microcystis aeruginosaand Aphanziomenon flos-aquae, a green alga Scenedesmus subspicatus anda wild type diatom Melosira sp. The experiments were performed usinglaboratory scale ultrasonic equipment covering frequencies between 20 kHzand 1.15 MHz, and power ranges of 200-420Watts.Key results have demonstrated a relationship between energy input per unitvolume and cell removal efficiency. For instance Microcystis aeruginosaneeded 100kWh/msup3/sup at a frequency of 20-30 KHz to remove 60% of cells, afterwhich no bloom recovery can occur. Aphanziomenon fq. required lowerenergy only 20-30kWh/msup3/sup but a higher frequency of 1144kHz for 100% cellremoval. Coupling the removal data and Chlorophyll fluorescence and TEMimaging has enabled the impact of ultrasound and algal physiology to beestablished. When the energy input increases beyond 278kWh/Msup3/sup critical cellrupture is reached producing removal rates of 60% for Microcystis aeruginosabelow this energy level limited removal is observed which is thought to be dueto the inability of cell rupture to occur. The paper concludes by comparingultrasound to other algal removal technologies to establish under whichsituation it becomes the most appropriate technology selection. Includes 21 references, figures.

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Edition: Vol. - No. Published: 11/01/2008 Number of Pages: 9File Size: 1 file , 740 KB