Dissolved air flotation combined to biosurfactants: a clean and efficient alternative to treat industrial oily water

The present review was motivated by the increasing demand of environmental regulatory agencies for the treatment of oily water generated during industrial activities. Flotation is a promising process for this purpose. Particularly, dissolved air flotation (DAF) is the most indicated technology due to its high efficiency and the possibility of controlling the physical variables, such as microbubble size, residence time and concentration of the effluent. DAF can also be optimised with the use of biodegradable tensioactive agents that increase the adhesion of oil particles, thereby enhancing the efficiency of the process. Among such tensioactive agents, biosurfactants are a viable, innovative, eco-friendly option with important properties, such as a reduction in surface tension, low toxicity and stability in the presence of adverse environmental conditions. Therefore, the aim of the present review is to offer a new perspective regarding the use of the flotation process combined with these specific biomolecules.