Dissolved Air Flotation: A Review from the Perspective of System Parameters and Uses in Wastewater Treatment

Abstract

The current issues of climate change and high freshwater demand worldwide have promoted the implementation of wastewater reclamation technologies. This study aims to review the efficiency of the dissolved air flotation (DAF) technique in a wide variety of applications in the agricultural, industrial, domestic, and municipal sectors, which have high freshwater consumption worldwide. We made a systematic review of the DAF technique in wastewater treatment in 2015-2021. We reviewed six indexed databases and governmental statistical reports; we used the keywords: dissolved air flotation, microbubbles, wastewater treatment, and the main operating and design parameters involved in the effectiveness of the flotation process. Additionally, we conducted a review of the most common synthetic coagulant studies used with DAF, as well as natural coagulants that promise to mitigate current climate change. Finally, we discussed advantages, disadvantages, and potential future studies. DAF to have considerable potential for wastewater treatment, as well as for waste utilization. The generation of large quantities of DAF sludge is a breakthrough for clean energy production, as it allows the use of this waste for biogas production.

Flotation performance of phosphate ore before and after dissolved air flotation water treatment

“…This process is followed by sudden decompression through a needle-type valve or flow constriction devices, resulting in the formation of microbubbles in the range of 10 to 100 μm. This technique has been employed in several areas, particularly for treating some industrial effluents [9] and in the agricultural sector [10]. Examples of industrial applications for removing suspended solids and adsorbed ions in Fe(OH) 3 precipitates occur in Chile, where DAF plants are used, enabling the reuse of treated water for irrigation and recycling in various unit operations for ore treatment [11].…”

Common Issues in Aeration System Choice for Flotation Wastewater Treatment

“…There can be also nutrients, pathogens, detergents and sometimes antibiotics in the water. The release of such effluents without prior treatment has a negative impact on ecosystems and is unacceptable [1].…”

“…There are also methods in which an air-water mixture is formed using ejectors and pneumohydraulic aerators [5]. DAF is considered to be the most commonly used technology for wastewater treatment in various sectors: agricultural, industrial and domestic and municipal [1]. Examples of wastewater treated with DAF are: oilrefinery wastewater [6,7], diary wastewater [8,9], textile wastewater [10], and restaurant wastewater [11].…”

Feasibility of dissolved air flotation for drinking water treatment for Harare

“…Therefore, DAF is cost-effective and efficient for algae removal. However, the advantages of algae removal using DAF have not been fully exploited in southern Africa, where CWTPs are commonly used although, the technology has been used in South Africa as stated by Muñoz-Alegría et al (2021). An example of an algae-infested raw water source for drinking water is Lake Chivero in Zimbabwe (Dandadzi et al 2020).…”