This is an expanded version of the Keynote lecture entitled "Innovations and Future Trends in Flotation Cell Design" delivered at Minerals Engineering ＇98. A category of flotation cell is discussed based on devices in the waste management industry. Seven examples of flotation cells utilized in waste paper deinking industry are reviewed to show the variety of approaches used to optimize the characteristics of a Potation system. rn attempting to identify the key fundamental parameters, it is noted that comparisons of flotation effectiveness on the basis of bubble surface area flux (BSAF) often fail to reveal differences between flotation devices. This led to the conclusion that perhaps comparisons should be based on cost per delivered BSAF.