Ultrasound enhancement of near - neutral photo - Fenton for effective E . coli 1 inactivation in wastewater 2 3

19 In this study, we attempt for the first time to couple sonication and photo-Fenton for bacterial 20 inactivation of secondary treated effluent. Synthetic wastewater was subjected to sequential high21 frequency/low power sonication, followed by mild photo-Fenton treatment, under a solar simulator. It 22 was followed by the assessment of the contribution of each component of the process (Fenton, US, hv) 23 towards the removal rate and the long-term survival; sunlight greatly improved the treatment 24 efficiency, with the coupled process being the only one to yield total inactivation within the 4-h period 25 of treatment. The short-term beneficial disinfecting action of US and its detrimental effect on bacterial 26 survival in long term, as well as the impact of light addition were also revealed. Finally, an 27 investigation on the operational parameters of the process was performed, to investigate possible 28 improvement and/or limitations of the coupled treatment; 3 levels of each parameter involved 29 (hydraulic, environmental, US and Fenton) were tested. Only H2O2 increased improved the process 30 significantly, but the action mode of the joint process indicated potential cost-effective solutions 31 towards the implementation of this method. 32