Singing Algae to Sleep: Understanding the Use of Ultrasound for Algal Control

摘要

The use of ultrasound technology to treat algal blooms is a relatively new option for water companies which have a huge potential as an alternative to chemical water treatment. It works by concentrating the energy of sound waves through cavitation causing the compression, rarefaction, and finally implosive collapse of bubbles in a liquid).This collapse by cavitation produces intense local heating (5,000°C) and high pressure (2000 atm) and is very short lived. Numerous studies have been carried out on cyanobacterial species and ultrasound but a comprehensive study using ultrasound on all the problematic species concurrently has not been completed to date. The aim 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.