Influence of ultrasound on phenol removal by adsorption on granular activated carbon

One of the most popular means for removal of natural organic matter found in small concentration is by adsorption. Recent studies have found that ultrasound enhances adsorption properties of different adsorbents for many contaminants in aqueous solution. This work describes the results of investigation carried out to examine the adsorption process of phenol, as an organic matter indicator, both from aqueous solution and from domestic wastewater on granular activated carbon (GAC) in absence and presence of ultrasound (US). The influence of ultrasonic power on the oxidation of phenol was also investigated at three different densities (1.06, 1.60 and 3.20 W/ml). The effects were monitored in terms of UV-absorbance at 270 nm, TOC and COD. Reduction of UV-absorbance and TOC have been negligible with US treatment alone and the performances have been better with adsorption into GAC. However, the adsorption rate of phenol in wastewater in presence of ultrasound, for an acoustical power of 1.06 W/ml, was twice higher than that obtained by simple stirring. Indeed, the combined employment of GAC adsorption and US can drastically remove organic substance thanks to a produced synergistic effect. Therefore, the combination of ultrasound and stirring for the adsorption process was shown to be of interest for the treatment of wastewater.