Coagulants Aided by Ultrasounds in the Water Treatment

Abstract

The paper is concerned wit the possibility of an intensification of the coagulation process with an ultrasonic field act ion. Investigations carried out in this direction, including the analysis of the changes of the natural water colour and turbidity in the laboratory set with a chemical coagulant and with additional sonification. The ultrasonic field was used with different intensity, with the variable vibration amplitude of 8-16!1m and the time of exposure 1-5minutes. The coagulation process in water with a selected coagulant-aluminium sulphate was simulated in the laboratory set, in which a fast and slow mixing and sedimentation process was carried out. In the tests, the confirmation of coagulation aided by ultrasounds was obtained, and moreover, this indicates the decrease of water colour and turbidity. These results depended on the ultrasonic field parameters and the quality of raw water as well. The dependence of efficiency coagulation-aided on the vibration amplitude and sonification time is presented in the figures. The efficiency of the process obtained during the tests was about 15%. Only for the samples of water with the high initial electrokinetic potential 1;, the decrease of water turbidity and colour correlated with this parameter decrease. No effect of destabilization of colloids in the other samples, indicated on the mechanism-aided connected with the oxidation action in the ultrasonic field. It confirmed the additional decrease of water oxygen consumption study to the coagulation process in the set with sonification .