AN ATTEMPT TO UNDERSTAND DISSOLVED AIR FLOTATION USING MULTIVARIATE DATA-ANALYSIS

In order to optimize the dissolved air flotation (DAF) process, a math ematical relationship should be established between the operating vari ables and the quality of the effluent water. In this study, operating parameters, including influent wastewater characteristics, were relate d to suspended solid (SS), COD, BOD5 and turbidity of the effluent via an empirical mathematical model. The data presented in this study wer e obtained from a pilot plant DAF study carried out on municipal waste water at Lee, Massachusetts to determine the operating conditions for the wastewater clarification. Response surface methodology was used to determine optimal conditions and to study the variations of flotation behaviour with varying operating conditions. The multivariate techniq ue used in this study is an extremely valuable tool to analyze data ob tained from actual wastewater treatment processes where the characteri stics of the wastewater are constantly changing. Without such a tool i t may not be possible to draw valid conclusions. In addition, this tec hnique requires comparatively fewer experiments when compared to tradi tional methods. Addition of more flocculant and recycle water over wha t is required actually decreases the effluent water quality. Tests car ried out with the same DAF unit at Little Rock, Arkansas and Birmingha m, Alabama have confirmed the accuracy of the predictions from the mod el.