Acoustic cavitation is known to produce conditions extremely suitable for the destruction of pollutants but the industrial use is hampered by the lack of suitable scale-up/design strategies and lack of studies at pilot scale of operation. In the present work, the efficacy of acoustic cavitation for the destruction of phenol has been investigated using a novel triple frequency flow cell with a maximum capacity of 7.5 l. The results obtained have been compared with the conventional laboratory scale ultrasonic horn, which is most commonly used for the applications based on acoustic cavitation and another side entering sonochemical reactor with capacity of 400 ml again based on irradiation with single transducer at frequencies similar to the conventional horn. In the novel sonochemical reactor, the effect of frequency of irradiation on the rates of degradation has also been investigated. Some process intensification studies have also been carried out using surface cavitation in the large-scale reactor as well as the ultrasonic horn with an aim of increasing the rates of degradation. (C) 2003 Elsevier B.V. All rights reserved.