Oil Removal from Produced Water during Laboratory- and Pilot-Scale Gas Flotation: The Influence of Interfacial Adsorption and Induction Times

Abstract

The significance of interfacial chemistry for the oil removal efficiency during flotation was demonstrated in a series of laboratory flotation and pilot-scale compact flotation unit (CFU) tests. Three crude oils with different physicochemical properties were used in the investigations. The differences in drop size distributions and densities of the oils could not fully account for the observed oil removal. However, taking the time for drainage and rupture (i.e., induction time) of the thin aqueous film separating the drops and bubbles into consideration resulted in good agreement with the oil removal. Moreover, it was demonstrated in a modified CFU setup that water-soluble hydrocarbons adsorbed onto the bubbles and reduced the oil removal. This was most likely as a result of increased induction times caused by the adsorbed components.

Statistical Modelling of Oil Removal from Surfactant/Polymer Flooding Produced Water by Using Flotation Column

“…Nitrogen gas was injected through a 40-100 µm pores sparger plate at the bottom of the flotation column for the total time of 10 min. The pores size and duration of the flotation process was estimated from the work according to the work by Eftekhardadkhah et al [2]. Samples at the water outlet were collected for every 2, 6 and 10 min and the oil concentration in the effluents was measured by a TD-500D device (UV-fluorescence technique).…”

“…Three experiments were performed to validate Eq. (2). A random condition with the gas flow rate of 3 L/min, polymer concentration of 450 ppm, the surfactant concentration of 250 ppm and duration of 10 min with the efficiency of 52.78% was selected for the validation.…”

“…The objectives of the produced water treatment are to remove the oil, desalination, removal of soluble organics, naturally radioactive materials, dissolve gases, suspended particles and sand, disinfection and softening [1]. These polluting components must be minimized to allow the level and threshold of oil in the produced water is limited by legislation during the discharging [2]. In Malaysia, the limit of monthly oil discharged is below 40 ppm [3].…”

Removal of oil from polymer-produced water by using flotation process and statistical modelling

“…Lastly, the tertiary separator embeds nutshell media filters for dissolved matter removal. In the flotation unit, the presence of gas bubbles enhances the floatability of oil and minimises separation time (Eftekhardadkhah et al 2015). Thus, it is essential to optimise flotation parameters, such as gas flowrate, feed flowrate, gas bubble size, duration of flotation, and temperature, in order to enhance the efficiency of oil removal.…”

“…As for the flotation process, the generated gas bubbles increase the density between the continuous and dispersed phases, hence increasing velocity (Eftekhardadkhah et al 2015).…”