Large scale environmental applications of high power ultrasound

In the present work, the use of high power ultrasound as a process tool for the removal of persistent organic pollutants (POPs) from soil and the treatment of bauxite red mud waste from the Bayer process is discussed. Laboratory scale experiments have confirmed that the application of high power ultrasound to slurries of contaminated soil and of bauxite ore can treat two major environmental problems cost-effectively. Destruction rates of POPs in soil of 90% and higher have been achieved whereas 85% iron oxide has been extracted from red mud waste leaving a low-iron fraction of approximately 50% by weight which is more environmentally friendly. A 4 x 4 kW pilot plant capable of treating 2.5 tonnes of slurry per day has been commissioned to provide more accurate estimates of power and energy requirements to allow scale-up to industrial use. (C) 2009 Elsevier B.V. All rights reserved.