Gas attachment of oil droplets for gas flotation for oily wastewater cleanup

Moosai, Roshni; Dawe, Richard A.

doi:10.1016/s1383-5866(03)00091-1

Cited by 171 publications

(79 citation statements)

References 22 publications

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“…If surfactants are present, the oil may be emulsified. Surfactant molecules adsorb at fluid interfaces and modify interfacial properties by lowering the surface or interfacial tension (Moosai et al, 2003). Adsorbed surfactants may become charged due to the loss of a molecular group.…”

Section: Oil-water Separation Techniquesmentioning

confidence: 99%

“…The separation driving force is the increased difference in buoyancy of an attached oil droplet (Rubio et al, 2002). For efficient flotation, chemical pretreatment is required to increase the oil droplet size (Al-Shamrani et al, 2002), to at least 60 µm (Moosai et al, 2003). An increased oil droplet size increases the rate of collection by air bubbles.…”

Section: Oil-water Separation Techniquesmentioning

confidence: 99%

“…Repulsive electrostatic forces prevent coalescence. Introducing an opposite charge modifies the negative charge, encouraging oil droplets to coagulate and assisting in the attachment of coagulated oil droplets to the negative air bubbles (Moosai et al, 2003). Air bubbles in water are considered to have a negative surface charge due to their negative zeta potential.…”

Section: Coagulationmentioning

confidence: 99%

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Oil removal from industrial wastewater using flotation in a mechanically agitated flotation cell

Welz¹,

Baloyi²,

Deglon³

2010

WSA

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This paper investigates the flotation of oil from wastewater in a laboratory-scale mechanically agitated flotation cell. Mechanical flotation cells are used commercially for oil flotation but, to the authors' best knowledge, there are no studies on their flotation performance in the literature. Some researchers have suggested that mechanically agitated systems are inappropriate for oil flotation as the high shear rates may break up the fragile organic flocs. The chemical pretreatment operating factors of pH and type of acid adjustor, coagulant type and dosage and flocculant dosage were firstly investigated. When using H 3 PO 4 for pH adjustment, a preferential pH of 5.5 was identified. When using H 2 SO 4 , a pH of 5.5 was not optimal. The acid type was subsequently the determining factor. Al 2 (SO 4 ) 3 was a more effective coagulating agent than lime, based on coagulant and flocculant dosages required (0.5mg/ℓ when using Al 2 (SO 4 ) 3 and 1.5 mg/ℓ when using lime). The flotation cell operating factors of aeration rate and impeller speed were subsequently investigated. Oil removal rates were found to increase at higher levels of aeration and agitation. This suggests that oil flotation is both possible and beneficial in high-shear turbulent environments. However, residual oil concentrations could not be reduced to below 50 to 100 mg/ℓ which is higher than the desired target of 50 mg/ℓ.

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Section: Oil-water Separation Techniquesmentioning

confidence: 99%

Section: Oil-water Separation Techniquesmentioning

confidence: 99%

Section: Coagulationmentioning

confidence: 99%

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Oil removal from industrial wastewater using flotation in a mechanically agitated flotation cell

Welz¹,

Baloyi²,

Deglon³

2010

WSA

View full text Add to dashboard Cite

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“…(4) and (5). Theoretically, increasing the interfacial area (a) helps to enhance the removal performance due to the fact that a larger available contact area leads to a higher chance of attachment [18]. As suggested in other reports, when using similar air flow rates, a smaller bubble size is preferred.…”

Section: Effects Of Bubble Hydrodynamic and Mixing Parameters On The mentioning

confidence: 92%

Prediction Model for the Treatment of Stabilized Oily Wastewater by Modified Induced Air Flotation (MIAF)

Romphophak

Chalermsinsuwan

Chawaloesphonsiya

et al. 2016

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Abstract. The objective of this study is to propose a prediction model for characterizing stabilized oily-wastewater that has been treated using Induced Air Flotation (IAF) and Modified Induced Air Flotation (MIAF), which is a combination of coagulation and flotation. Wastewater samples containing an anionic surfactant at the critical micelle concentration (CMC) were prepared as the stabilized oily-emulsion. The amount of oil as well as the amount removed was measured using COD. The study shows that the coagulant dosage (CAlum), interfacial area (a), and velocity gradient (G) are the important factors that affect flotation performance. Therefore, the proposed model is based on these parameters in terms of the CAlum and a/G ratio. The maximum removal efficiency and the reduction of the COD values can be predicted for any of the operating conditions. It was found that predicted oily wastewater efficiency and removal kinetic were compatible with those obtained from experiments. The discrepancy of 5% between the results from the prediction and the experiment can be found.

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“…Lastly, the conglomerate of oil droplets with air bubbles can quickly rise to the top of water/oil mixture, and the accumulated oil can be skimmed off and collected for further purification (Moosai and Dawe, 2003). Ramaswamy et al (2007) applied froth flotation treatment for oil-water separation from oily sludge, and they observed an oil recovery of up to 55% at the optimal flotation conditions.…”

Section: Froth Flotationmentioning

confidence: 99%

Development of novel oil recovery methods for petroleum refinery oily sludge treatment

Hu¹

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Oily sludge is one of the most significant wastes generated in the petroleum industry.It is a complex emulsion of various petroleum hydrocarbons (PHCs), water, metals, and fine solids. Due to its hazardous nature and increased generation quantities around the world, the effective treatment of oily sludge has attracted widespread attention. The complexity of its composition and diversity of its origin sources make oily sludge management a difficult and costly undertaking. Many methods have been developed for the treatment of oily sludge through oil recovery or sludge disposal approaches, but no single specific process can be considered as a panacea since each method is associated with different advantages and limitations. Efforts should focus on the improvement of current technologies and the combination of oil recovery with sludge disposal in order to comply with both resource reuse recommendations and environmental regulations. The object of this study was to develop novel combined methods for oil recovery treatment on different refinery oily sludges. The investigation focused on the oil recovery performance of combined methods based on four individual treatment processes including ultrasonic irradiation, solvent extraction, freeze/thaw, and pyrolysis in oily sludge treatment.Firstly, the oil recovery and salt removal effects of ultrasonic irradiation on oil refinery tank bottom sludge were investigated, together with those of direct heating.Ultrasonic power, treatment duration, sludge-to-water ratio, and initial sludge-water slurry temperature were examined for their impacts on sludge treatment. It was found that the increased initial slurry temperature could enhance the ultrasonic irradiation performance, especially at lower ultrasonic power level (i.e., 21 W), but the application of higher-power ultrasonic irradiation could rapidly increase the bulk temperature of slurry. Ultrasonic 2 irradiation had a better oil recovery and salt removal performance than direct heating treatment. More than 60% of PH Cs in the sludge was recovered at an ultrasonic power of 75 W, a treatment duration of 6 min, an initial slurry temperature of 25 °C, and a sludgeto-water ratio of 1 :4, while salt content in the recovered oil was reduced to <5 mg/L, thereby satisfying the salt requirement in refinery feedstock oil. In general, ultrasonic irradiation could be an effective method in terms of oil recovery and salt removal from refinery oily sludge, but the separated wastewater still contains relatively high concentrations of PH Cs and salt which requires proper treatment.Two types of ultrasonic assisted extraction (UAE) treatment including UAE probe (UAEP) system and UAE bath (UAEB) system were investigated for oil recovery from refinery oily sludge. Their oil recovery efficiencies were compared to that of mechanical shaking extraction (MSE). Three solvents including cyclohexane (CHX), ethyl acetate (EA), and methyl ethyl ketone (MEK) were examined as the extraction solvents. The influence of experimental factors on oil an...

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Gas attachment of oil droplets for gas flotation for oily wastewater cleanup

Cited by 171 publications

References 22 publications

Oil removal from industrial wastewater using flotation in a mechanically agitated flotation cell

Oil removal from industrial wastewater using flotation in a mechanically agitated flotation cell

Prediction Model for the Treatment of Stabilized Oily Wastewater by Modified Induced Air Flotation (MIAF)

Development of novel oil recovery methods for petroleum refinery oily sludge treatment

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