Abstract
Flotation constitutes a separation process that originated from mineral processing. Nowadays, wider applications have been found and compared to flotation for water and wastewater treatment. Stress in the present review paper was mainly applied to heavy metal ions recovery by flotation and the respective mechanism followed, being either ion, precipitate, or sorptive flotation. In the latter case, the use of adsorbents is included (such as powdered activated carbon, zeolites, and goethite), as well as various biosorbents. The flotation of the following metals was reviewed: copper, zinc, nickel, lead, iron, chromium, arsenic, gold, and others. The bubble generation method could be applied for typical dispersed-air flotation column, electroflotation, or dissolved-air flotation; the latter being the most appropriate established technique in water treatment. The role of particle size (for example, studying flotation of salt-type mineral fines) was also examined.
Highlights
Flotation is known as a separation process, based on the introduction of gas bubbles as the transport medium
The scope of the present paper is to review the floatation process in-depth, including updating the current literature in the area of wastewater treatment
Ion flotation involves the removal of surface-inactive ions from aqueous solutions by adding surfactants or collectors, usually with an ion having a charge opposite to that of the metal ion to be removed [16,17]
Summary
Flotation is known as a separation process, based on the introduction of gas bubbles as the transport medium. A coagulation-flotation method (using an anionic surfactant and a cationic polyelectrolyte) was designed for the rapid removal of tetracycline antibiotics from water [10]. The latter are broad-spectrum antibiotics commonly used in livestock farming and often prescribed for human therapy. Processes 2018, 6, 116 removal by (dissolved-air) flotation was analyzed at combined sewer overflows, which usually contain sewage and rainwater [12]. These are thought to be the main cause of eutrophication and algae occurrence in lakes. Sustainability issues in this area have been recently expressed [14,15]
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