Optimizing the Air Dissolution Parameters in an Unpacked Dissolved Air Flotation System

Abstract

Due to the various parameters that influence air solubility and microbubble production in dissolved air flotation (DAF), a multitude of values that cover a large range for these parameters are suggested for field systems. An unpacked saturator and an air quantification unit were designed to specify the effects of power, pressure, temperature, hydraulic retention time, and air flow on the DAF performance. It was determined that a pressure of 621 kPa, hydraulic retention time of 18.2 min, and air flow of 8.5 L/h would be the best controlled parameters for maximum efficiency in this unit. A temperature of 7 °C showed the greatest microbubble production, but temperature control would not be expected in actual application. The maximum microbubble flow from the designed system produced 30 mL of air (±1.5) per L of water under these conditions with immediate startup. The maximum theoretical dissolved air volume of 107 mL (±6) was achieved at a retention time of 2 h and a pressure of 621 kPa. To isolate and have better control over the various DAF operational parameters, the DAF unit was operated without the unsaturated flow stream. This mode of operation led to the formation of large bubbles at peak bubble production rates. In a real-world application, the large bubble formation will be avoided by mixing with raw unsaturated stream and by altering the location of dissolved air output flow.

Recovery of ink particles in a concurrent column flotation

“…The average total residence time was found to be of the order of 20 s. This is shorter than that of conventional column flotation devices, the residence time of which is reported to be a few minutes [16,30], and much shorter than that of microbubble-producing devices (~20 min) [31]. The shorter residence time gives rise to a higher throughput, making it capable of treating more pulp in a shorter time.…”

Oily water treatment in a multistage tower operated under a novel induced pre-saturation process in the presence of a biosurfactant as collector

“…The IPST continuous prototype operated with three stages with and without the addition of the biosurfactant. The manometric height of the pumps was set at 6 bar according to Dassey and Theegala [ 34 ].

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Influence of diffuser design on selected operating variables for wastewater flotation systems: a review

“…In this case, bioflocculants are suitable to impart environmental benignity (Mukandi 2017). There are various other factors apart from process operating variables that are considered when designing a flotation system, these include the type and quality of wastewater, the extent of the contamination, the level of treatment required and the type of diffusers to be used (Dassey & Theegala 2011). Most existing studies are vague in terms of disclosing the geometry or properties of air releasing devices used in flotation systems.…”