We investigated the dewaterability and physiochemical properties of digested sludge after treatment with ultrasonic energy for the purpose of reducing sludge. The study involved laboratory experimentation under varying test conditions of treatment time, volume of sludge and ultrasonic energy, which combined can be denoted as specific supplied energy (E(v)). Results of the experiments show that particle size (dp(50), dp(10), U) of the ultrasonically treated sludge decreases due to the separation of sludge flocs. Capillary suction times (CSTs) decrease significantly, while turbidity, VDSs/VS and SCODs/TCOD increase with ultrasonic treatment. From these results, it was found that the ultrasonic treatment specified by the supplied energy (E(v)) can not only improve dewaterability but also reduce the volume and mass and change the chemical properties of sludge.

The use of ultrasound as an enhancement mechanism in the surfactant-aided soil-washing process was examined by conducting desoption tests of soils contaminated with naphthalene or diesel-oil. The experiments were conducted to elucidate the effect of ultrasound on the mass transfer from soil to the aqueous phase using naphthalene-contaminated soil. In addition, the use of ultrasound for the diesel-oil-contaminated soil was investigated under a range of conditions of surfactant concentration, sonication power, duration, soil/liquid ratio, particle size and initial diesel-oil concentration. The ultrasound used in the soil-washing process significantly enhanced the mass transfer rate from the solid phase to the aqueous phase. The removal efficiency of diesel-oil from the soil phase generally increased with longer sonication time, higher power intensity, and large particle size.

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This study investigated the degradation of diethyl phthalate (DEP) by sonolytic, photolytic and sonophotolytic processes. Two types of UV lamps, UVC (254 nm) and VUV (185 nm+254 nm), were combined with ultrasound (283 kHz). The pseudo-first order degradation rate constants were in the order of 10(-1)-10(-3) min(-1) depending on the processes. The sonolytic DEP degradation rate increased with increasing applied power. Photolytic or sonophotolytic degradation of DEP when using a VUV lamp appeared to be effective because the photo ІІ (UVC/VUV) resulted in a significantly faster degradation than the photo І (UVC) processes due to the higher photon energy and higher hydroxyl radical generation by homolysis of water by VUV. Significant degradation and mineralization (TOC) of DEP were observed with the combined sonophotolytic processes. Moreover, synergistic effects of 1.68 and 1.23 were exhibited at DEP degradation of the sonophoto I and sonophoto II processes, respectively. This was attributed to the UV-induced dissociation of hydrogen peroxide (H(2)O(2)) generated by the application of US to hydroxyl radicals. Therefore, US in sonophotolytic processes can play an important role in enhancing DEP degradation. Moreover, the sonophoto ІІ process is more effective on the mineralization and biodegradability of DEP.