Thickening sludges by dissolved-air flotation thickeners (DAFT) is well established and has been around for many years. Some wastewater treatment plants (WWTPs) that implemented this technology in the past have upgraded their existing DAFT systems to continue with this technology. Others, however, have opted for other alternatives. This paper investigates the features which make a DAFT system successful and unique in affording benefits which go beyond the thickening function.