Dissolved air flotation (DAF) is one of the most important and effective process in the treatment of all types of water -industrial and urban wastewater treatment, water processing, water reuse and desalination processes-. It can be installed in different points of wastewater treatment line due to multiple design possibilities of dissolved air flotation units. In several occasions, dissolved air flotation system is installed at the beginning of the wastewater treatment process, immediately after the pretreatment to remove fat and grease. It also can be implanted at the inlet of biological treatment for reducing pollutant load. In other many times it is placed at the final of wastewater treatment line to clarify water before being discharged. In desalination -in which the development of fiber glass is starting to consolidate as construction material- it works to protect the membranes from the presence of algae in the water too. Furthermore, it can be installed at the top of the sludge treatment line as sludge thickener to reduce the volume. Dissolved air flotation is based on a physic-chemical process which separates solid and liquid particles by the addition of very small air bubbles. These bubbles stick on solid particles and give them a high rate of ascent. Once in the surface, the solids -the sludge- are pulled mechanically to the hopper. Dissolved air flotation gives a rate of ascent 5 times higher than settling speed in a conventional settling tank, thereby saving time and space.