Separation Of Oil Droplets Research Articles

A digital image analysis approach to understand the microscopic and macroscopic phenomena in dissolved air flotation

Dissolved air flotation (DAF) is an effective method for separating suspended oil and solid particles from wastewater by utilizing small air bubbles. This study aims to investigate the impact of key factors, such as saturating pressure and water flow rate, on the separation of fine oil droplets from a water stream. The macroscopic flow patterns within the cell were analyzed using particle image velocimetry (PIV), while Digital Image Analysis (DIA) was employed to study microscopic phenomena, including oil droplet rising velocity and oil-bubble contact mechanisms. Our findings propose a safe operating window (specifically, water flow rate and saturation pressure) for the effective separation of oil droplets without any oil escaping into the clean water stream. It was found that the oil droplet rising velocity increases with the saturation pressure up to 200 kPa. However, a further increase in the pressure of the air saturating chamber leads to a decrease in oil droplet rising velocity. Additionally, we identified a peak in rising velocity at an oil droplet size of approximately 200 µm. Below this threshold, the rising velocity increases with droplet size, while for droplet sizes exceeding 200 µm, the rising velocity decreases with size. This behavior can be explained by the conflicting effects of droplet size increment according to the Stokes law for the rising velocity of oil droplets. As the droplet size increases, the average density of the bubbles/droplet aggregate rises, reducing the ∆ρ in the Stokes law and subsequently lowering the aggregate rising rate. However, as per the Stokes law, the oil droplet rising velocity increases proportionally to the square of its size.

Synthesis of biological nanocomposite fluids and enhanced crude oil recovery

Aiming at the problems of small pores, complex structure, large seepage resistance, and poor recovery effect in the development process of offshore medium and low permeability reservoirs, a green and environmental friendly biological nanocomposite fluid (BNF) was developed to enhanced crude oil recovery (EOR). Fe3O4@SiO2-Ag nanoparticles (NPs) were synthesized in the laboratory, and citric acid, tannic acid, sodium alginate, and trehalose lipids were used as surface modifiers for NPs and as fluid stabilizers. The nanocomposites were characterized by SEM–EDS, TEM, FTIR, XPS, XRD, and VSM. The EOR mechanism of BNF was studied by laboratory experiments, in which the interfacial tension can be reduced by 80 %. Moreover, 500 ppm BNF could keep oil and water emulsified for more than 3 months. Static separation of oil droplets and dynamic stripping of oil film exhibited obvious effects, and the bioactive substances’ dispersant and NPs can jointly drive away residual oil. The experiment on core displacement of crude oil showed that 500 ppm BNF can enhance oil recovery by 15.56 % on the basis of water flooding. The BNF oil displacement agent is economic and environmental friendly, providing a new method for the green and high-quality development of offshore oil fields.

Acoustophoresis of monodisperse oil droplets in water: Effect of symmetry breaking and non-resonance operation on oil trapping behavior.

Acoustic manipulation of particles in microchannels has recently gained much attention. Ultrasonic standing wave (USW) separation of oil droplets or particles is an established technology for microscale applications. Acoustofluidic devices are normally operated at optimized conditions, namely, resonant frequency, to minimize power consumption. It has been recently shown that symmetry breaking is needed to obtain efficient conditions for acoustic particle trapping. In this work, we study the acoustophoretic behavior of monodisperse oil droplets (silicone oil and hexadecane) in water in the microfluidic chip operating at a non-resonant frequency and an off-center placement of the transducer. Finite element-based computer simulations are further performed to investigate the influence of these conditions on the acoustic pressure distribution and oil trapping behavior. Via investigating the Gor'kov potential, we obtained an overlap between the trapping patterns obtained in experiments and simulations. We demonstrate that an off-center placement of the transducer and driving the transducer at a non-resonant frequency can still lead to predictable behavior of particles in acoustofluidics. This is relevant to applications in which the theoretical resonant frequency cannot be achieved, e.g., manipulation of biological matter within living tissues.

Biodegradable Chitosan-Based Membranes for Highly Effective Separation of Emulsified Oil/Water.

Efficient separation of oil droplets from oil/water emulsions is necessary for many energy and food industrial processes and for industrial wastewater treatment. Membrane microfiltration has been explored to address this issue because it is simple to operate and low in cost. However, filtration of oil droplets with a size around or less than 1 μm is still a major challenge. Furthermore, the fabrication process for polymeric membranes often uses hazardous organic solvents and petroleum-derived and nonbiodegradable raw materials, which pose additional environmental health and safety risk. In this study, we examined the use of chitosan-based membranes to efficiently remove oil droplets with an average diameter of ∼1 μm. The membranes were fabricated based on the rapid dissolution of chitosan in an alkaline/urea solvent system at a low temperature, thus avoiding the use of any toxic organic solvent. The chitosan membranes were further modified by dopamine and tannic acid (TA). The as-prepared membrane was characterized in terms of surface morphology, pore size distribution, and mechanical strength. The membrane performance was evaluated on a custom-designed crossflow filtration system. The results showed that the modified chitosan membrane with dopamine and TA had a water flux of 230.9 LMH at 1bar transmembrane pressure and oil droplet rejection of 99%. This water flux represented an increase of more than 10 times when compared with the original chitosan membrane without modification. The study also demonstrated excellent antifouling properties of the modified membrane that could achieve near 100% water flux recovery.

Preparation of modified membrane of polyvinylidene fluoride (PVDF) and evaluation of anti-fouling features and high capability in water/oil emulsion separation

The conventional Polyvinylidene Fluoride (PVDF) membrane was modified by polymerization Reversible addition−fragmentation chain-transfer (RAFT) with copolymer (PEGMA-co-BVIm-Br) on the upper bulk. This copolymer was obtained from the synthesis of (BVIm-Br) 3-butyl-1-vinyl-1-H-imidazole-3-ium bromide and the vinyl imidazole (VI) monomer N-vinyl imidazole (a hydrophilic monomer) and 1-bromobutane (C4H9Br). The analysis of such as ATR-FTIR, the magnetic resonance of H-NMR nuclei, zeta potential, Water Contact Angle (WCA), and Scanning Electron Microscopy (SEM) confirmed the presence of copolymer on the surface of the modified membrane. The bonding of this copolymer on the membrane surface reduced the WCA of the membrane water (from 89.5 ±1.96 to 33.8 ±1.55). The raw PVDF membrane (M1) and modified membrane (with total ratio-P(PEGMA-co-BVIm-Br) copolymer 2.5 % (M2), 5 % (M3), 10 % (M4), 20 % (M5), and 40% (M6) to (raw PVDF membrane) membrane showed appropriate hydrophilic nature and excellent separation of oil droplets from water/oil emulsions in the simulated effluent on the surface.This operation was performed for a comprehensive study on the determined parameters and by filtration with simulated petrochemical industry effluent (containing water/oil emulsion). Therefore, the recovery efficiencies of water flux, flow flux, oil recovery amount, as well as total fouling of M6 membrane were reported 96.14±0.99 and 428±2.6 L/ (m2 h), 96.1±1.3%, and 17.18±0.37%, respectively. This study aimed to prepare a copolymer-modified membrane that can show high performance in cleaning and resistance to various fouling, such as Rt, Rr, and Rir at the specified temperature, after long-term emulsion separation.

Nanopore-based active oil droplet filtration under negative DC dielectrophoresis for oily wastewater treatment

Efficient separation of oil droplets from oily wastewater is an essential task for handling the world water crisis and environmental pollution. However, existing passive oil/water separation technologies suffer from the drawbacks of relatively low separation efficiency and strict material requirements. We present an active dielectrophoretic oil/water separation technique without inducing further environmental contamination. Based on the non-uniform electric field generated through insulated nanopores under direct current (DC) voltage, an oil droplet experiences a negative dielectrophoresis (nDEP) force because of its weaker dielectric property compared with wastewater. Meanwhile, electroosmotic flow also occurs in oil/water separation devices due to the ion motion inside the electric double layer of the nanopore solid surface. Through developing a multiphysical model for immiscible oil/water flow under hybrid electrokinetic effects, the oil/water separation is investigated at different parametric conditions. Electrokinetic filtration of oil droplets through nanopores is successfully achieved when the nDEP force is dominant rather than the electroosmotic electrohydrodynamic (EHD) force for oil droplet movement. To enhance the oil/water separation rate, the relative strength between nDEP force and EHD force on an oil droplet is consolidated via increasing DC voltage, decreasing surface charge density, and optimizing the nanopore configuration. The designed active oil/water separation using DC-DEP offers significant potential for future oily wastewater treatment.

Hydrocylone for oil-water separations with high oil content: Comparison between CFD simulations and experimental data

Production separators for gas-oil-water separation are huge, require long residence times, and present several internals to improve oil-water separation. As an alternative to production separators, specially for subsea facilities, this work presents a hydrocyclone which separates a 40% oil-in-water mixture with 93% ± 2% total efficiency and flow ratio of 7%. Such high oil concentration is typical of mature wells and hydrocyclones have not been designed for such purpose before. In order to design this hydrocyclone, fractional factorial techniques have been used to consider the influence of seven geometrical variables. CFD has been used to assess the performance of each hydrocyclone of the factorial design. The selected hydrocyclone has been tested experimentally in order to validate its performance. PIV measurements have also been carried out in order to assess tangential and axial mean velocity profiles for only water flowing in the hydrocyclone. FBRM has been used to measure droplet size distribution at inlet, overflow and underflow streams. As results, computational reduced total efficiency has been experimentally confirmed. Numerical simulations captured tangential velocity near the centerline of the hydrocyclone, but failed in predicting axial velocity profiles and tangential velocity peaks and near wall regions. It has been discussed though that these are probably not responsible for oil droplets separation in the hydrocyclone when water is the continuous phase. A methodology to analyze the effect of droplet breakup and coalescence, using measured inlet, overflow and underflow cumulative size distribution, has been presented. It has been shown that for the inlet cumulative undersize distribution used, breakup was negligible and coalescence occurred only for droplet diameters higher than those separated with 100% grade efficiency. In this case, no breakup and coalescence models are thus needed in the mathematical model and this explains why reduced total efficiency has matched in both numerical simulations and experiments.

A NEW COMPUTATIONAL FLUID DYNAMICS STUDY OF A LIQUID-LIQUID HYDROCYCLONE IN THE TWO PHASE CASE FOR SEPARATION OF OIL DROPLETS AND WATER

Abstract A liquid-liquid hydrocyclone, so-called de-oiling equipment, was investigated for separation of oil droplets and wastewater in an Iranian petroleum unit. To generate the geometry and the mesh of the hydrocyclone Gambit software was used. Afterwards, by taking advantage of the Euler-Lagrangian principle, the governing equations covering the motion of fluid and that of particles in the hydrocyclone were solved. Initially, it was shown that the outcomes of CFD are in agreement with experimental data, and then 15 hydrocyclones with different overflow diameters, overflow lengths and input velocities were employed for more detailed analyses. The separation process through a hydrocyclone is counted as an economical process when ther is not only a low pressure drop inside the hydrocyclone, but also a high separation efficiency. As a result, regarding the mentioned criteria, the optimum hydrocyclone, whereby the highest performance of the hydrocyclone is exploited, was obtained by applying the 15 sets of CFD data to a Neural Network (NN) and then by optimizing the function generated by the NN by means of a Genetic Algorithm (GA). The innovation of this research work is the three-phase modeling.

Magnetically responsive multi-wall carbon nanotubes as recyclable demulsifier for oil removal from crude oil-in-water emulsion with different pH levels

A magnetically responsive multi-walled carbon nanotubes (M-MWCNTs) appropriate for acidic to alkaline conditions of crude O/W emulsion was designed and prepared via regulating the content of surface functional groups (such as -NH2, -OH and -COOH). The M-MWCNTs was confirmed as an efficient demulsifier and the corresponding demulsification efficiency achieved the highest when its dosage was increased to 400 mg/L. Significantly, the M-MWCNTs has superior demulsification performance under wide pH levels. What's more, the M-MWCNTs still has good demulsification efficiency after 5 cycles, suggesting it has high stability. The M-MWCNTs has strong interfacial activity, which can reach the oil-water interface and interact with asphaltenes. The synergistic π-π and/or n-π interaction of aromatics/functional groups of MWCNTs and asphaltenes as well as the electrostatic attraction between the M-MWCNTs and the asphaltenes promoted the oil separation from acidic crude O/W emulsion. In the neutral condition, the interfacial adsorption of π-π and/or n-π interactions was the main demulsification mechanism. Moreover, the electrostatic repulsion between the M-MWCNTs and crude O/W emulsion decreased due to the increase of amino groups under the alkaline condition. The protective film stabilizing the crude O/W emulsion was more facile broken, thusly promoting oil droplets separation from crude O/W emulsion.

Aggregation of oil droplets and demulsification performance of oil-in-water emulsion in bidirectional pulsed electric field

Electric field driven aggregation of oil droplets in oil-in-water (O/W) emulsion is a novel attempt for enhancing oil-water separation. The chaining and aggregation behavior of oil droplets in O/W emulsion under bidirectional pulsed electric field (BPEF) was studied in this work for the purpose of oil droplets separation from aqueous phase in O/W emulsion for the first time. The BPEF induced oil droplets to aggregate and take shape into three forms of congeries: oil-droplet chain, oil clusters and oil cluster chains. The aggregation effect of oil drops under BPEF voltage, frequency and duty cycle was explored by evaluating the size and formation time of congeries. It was discovered that BPEF voltage could enhance and accelerate oil droplets to aggregate but the aggregation effect was weakened by the increased BPEF frequency. And the best aggregation state of oil droplets under different duty cycles was achieved at BPEF duty cycle 70%. The demulsification performance of O/W emulsion under BPEF was investigated and its variation was consistent with the aggregation regularity and effect of oil drops in BPEF. Therefore, the microcosmic aggregation effect of oil drops in O/W emulsion under BPEF could be used to estimate the demulsification performance and separation effect of O/W emulsion.

Manipulation and separation of oil droplets by using asymmetric nano-orifice induced DC dielectrophoretic method

HypothesisEmulsion droplets are versatile tools in chemical and biological fields and the separation of emulsion droplets is one of the most crucial steps in research and industry. ExperimentsThis work developed a nano-orifice based DC dielectrophoretic (DEP) system for the sorting of oil-in-water emulsion droplets by size and content in a microchannel. Then, the size-dependent separation of oil droplets was conducted and verified by the prediction of theoretical simulation. In addition, by selecting the suspending solution with a specific electrical conductivity, the oil droplets with similar sizes but different contents were separated based on their opposite DEP behaviors. FindingsThe size-dependent separation of smaller silicone oil droplets (7.5 and 11 µm in diameter) with a high separation resolution, i.e., size difference of only 3.5 µm was achieved and showed good agreement with the simulation results. The positive and negative DEP behaviors of the droplets varying with the electrical conductivity of the suspending solution were discussed and different types of droplets of similar sizes but different contents were separated. This paper presents the DC-DEP method based sorting of emulsion droplets by size and content in nanofluidic chip for the first time, providing a platform to manipulate individual emulsion droplet.

Separation of Janus droplets and oil droplets in microchannels by wall-induced dielectrophoresis

The continuous separation of different types of droplets from a mixture is important in industrial and research applications. Currently researches for droplet separation focus on homogeneous emulsion droplets, and there is no study on the separation of heterogeneous droplets. The wall-induced dielectrophoresis, which originates from the non-uniform electrical field around a sphere nearby a planar wall, can be applied to separate dielectric particle and cells. In this work, the continuous separations of oil droplets and the electrically induced Janus droplets (EIJDs) in a microchannel by using the wall-induced dielectrophoresis method were presented. The wall-induced dielectrophoretic lateral migration of a droplet depends on the size and surface charge of the droplet. In this study, the wall-induced dielectrophoretic lateral migrations of oil droplets and Janus droplets in a straight microchannel under different strengths of electrical fields were investigated first, and the experimental results match well with the theoretical predictions. Then, the separations of oil droplets by size, separations of Janus droplets by size, and separation of mixtures of Janus droplets and oil droplets with the same size were conducted, respectively. The experimental results demonstrate that, with this method, the separations of target oil droplets or Janus droplets with specific size can be accomplished by simply adjusting the voltages applied to the microchannel.

Biosurfactant assisted recovery of the C5-C11 hydrocarbon fraction from oily sludge using biosurfactant producing consortium culture of bacteria

A biosurfactant producing culture of bacteria was isolated from an automobile engine oil dump site which was later used as an inoculum in batch and continuous flow oil recovery from oily sludge. Initially, an emulsion of oily sludge was prepared by mixing 5% m/v solids: 21% v/v bituminous sludge: 77% v/v water. The isolated cultures were added to vessels with stable emulsions to facilitate the separation of oil droplets from the sludge matrix. In batches with live cultures, up to 35% oil recovery was achieved after incubation for 10 days. Further investigations were conducted in a semi-continuous feed, fed-batch plug flow reactor (FB-PFR) system. Up to 99.7% was achieved in the FB-PFR after operation for 10 days, much higher than the recovery achieved in the pure batch systems where only 35% oil was recovered after incubation for 10 days. The improved performance in the FB-PFR was attributed to differential separation of particles under variable velocity along the reactor. The culture in the reactor was predominated by Klebsiellae, Enterobacteriaceae and Bacilli throughout the experiment. A crude biosurfactant produced by the cultures was partially purified and analyzed using the liquid chromatograph coupled to a tandem mass spectrometer (LC-MS/MS) which showed that the molecular structure of the biosurfactant produced closely matched the structure of lipopeptides identified in earlier studies. This process is aimed at recovering useful oil from oily waste sludge with the added advantage of degrading aromatic organic impurities in the oil to produce a cleaner oil product. The further advantage of the FB-PFR system was that, the bacteria discharged together with effluent sludge residue further degraded chemical oxygen demand (COD) in the treated sludge thereby reducing the polluting potential of the final disposed sludge.

A multi-module microfluidic platform for continuous pre-concentration of water-soluble ions and separation of oil droplets from oil-in-water (O/W) emulsions using a DC-biased AC electrokinetic technique.

A novel continuous flow microfluidic platform specifically designed for environmental monitoring of O/W emulsions during an aftermath of oil spills is reported herein. Ionized polycyclic aromatic hydrocarbons which are toxic are readily released from crude oil to the surrounding water phase through the smaller oil droplets with enhanced surface area. Hence, a multi-module microfluidic device is fabricated to form ion enrichment zones in the water phase of O/W emulsions for the ease of detection and to separate micron-sized oil droplets from the O/W emulsions. Fluorescein ions in the water phase are used to simulate the presence of these toxic ions in the O/W emulsion. A DC-biased AC electric field is employed in both modules. In the first module, a nanoporous Nafion membrane is used for activating the concentration polarization effect on the fluorescein ions, resulting in the formation of stable ion enrichment zones in the water phase of the emulsion. A 35.6% amplification of the fluorescent signal is achieved in the ion enrichment zone; corresponding to 100% enrichment of the fluorescent dye concentration. In this module, the main inlet is split into two channels by using a Y-junction so that there are two outlets for the oil droplets. The second module located downstream of the first module consists of two oil droplet entrapment zones at two outlets. By switching on the appropriate electrodes, either one of the two oil droplet entrapment zones can be activated and the droplets can be blocked in the corresponding outlet.

Separation of oil drops from water using stainless steel fiber bed

This study is focused on the separation of oil droplets from water by applying a stainless steel fiber bed. The separation efficiency was followed by monitoring the oil concentration of three mineral oils that have a wide range of viscosity from 10 to 170 mP s, as well as neutralization number from 0.10 to 1.70 mg KOH/l. The bed properties were varied by altering the bulk density of the filter material, which resulted in a change of bed permeability from 0.7?10-9 to 5.389?10-9 m2 and bed porosity from 91 to 98%. All experiments were conducted in a wide range of superficial velocity from 10 to 50 m/h. It can be concluded that high separation efficiency was achieved using stainless steel fibers, reaching values over 90%. Low bed permeability is most favorable for work at the selected conditions for the separation. The operation of stainless steel fiber bed is very sensitive to changes in the properties of oils. For lower viscosity of oily contaminants, the required efficiency of separation is achieved at lower superficial velocity through the fibrous bed. This phenomenon can be considered as a serious drawback since the bed coalescers often have to separate oils of different quality over time.

Investigation on the oil–gas separation efficiency considering oil droplets breakup and collision in a swirling flow

In this study, the oil droplets separation process in a swirling flow was investigated using numerical simulations and verification experiments. Numerical models were established to investigate the effects that the collision and breakup of droplets and the collision between droplets and wall on separation efficiency, respectively. The separation efficiencies were calculated using different models under various inlet velocities, from 10 to 18m/s. The simulated results showed that droplets colliding could improve the separation efficiencies with up to 22.4% increments at the 10m/s inlet velocity for droplets with a diameter of 10μm. The oil–gas separation efficiency was reduced up to 17.4% due to the oil droplet–wall interaction in swirling flow when the simulation model involved droplet–wall collisions. The simulated separation efficiencies showed little change when oil droplet breakups were considered in the model under different inlet velocities and droplet diameters. A test rig was built to validate the simulation results. It showed good agreement between the experimental data and simulated results. Thus, the numerical simulation model could be used to predict separation performance and understand the separation process in a swirling flow.

Acoustic separation of oil droplets, colloidal particles and their mixtures in a microfluidic cell

Here we report direct macroscopic and microscopic observations of acoustic driven separation of dodecane oil droplets in water in the presence and absence of colloidal silica particles suspended in the water phase. The experiments were conducted in a simple rectangular channel glass microfluidic cell in which an ultrasound standing wave pattern was generated at 300KHz frequency. The separation process of both oil droplets and colloidal particles inside the cell was recorded using a high-speed video camera equipped with a macro-objective lens for macroscopic observation or with a high-speed camera attached to an inverted optical microscope for a higher resolution microscopic observation. We characterize the clustering process in the case of emulsion droplets or solid colloidal particles and ultimately demonstrate the emulsion droplets separation from the solid particles in the mixtures based on their different acoustic contrast factors. Finally, we conduct proof of concept experiment to show that the same approach can be used in a continuous fluid flow process.

Separation of Oil Droplets from Oil-in-Water Emulsion Using a Microbubble Generator

The induced air flotation of oil droplets was performed using a microbubble generator to develop a simple and energy saving method for oil-in-water emulsion separation. The microbubble generator, which consisted of a liquid pump and a special line mixer, was set at the bottom of a bubble column. The effects of operation conditions on the oil separation performance were investigated. A sintered glass gas sparger was also used to disperse millibubbles. Oil-in-water emulsions were prepared from soybean oil and water. Compared with millibubbles, the dispersion of microbubbles effectively separated oil. This was because microbubbles had high efficiency of collision with droplets and it was difficult to detach droplets because of the low rising velocity of microbubbles. Millibubbles were difficult to attach to oil droplets and easy to detach droplets because of the high velocity movement of bubbles. The oil separation ratio was a maximum at the gas velocity of 0.2 mm/s because the amount of millibubbles increased as the gas velocity became higher above 0.4 mm/s. The oil separation was largely enhanced at the solution pH below 4.5. The zeta potential of droplets was negative in the pH range from 3 to 11. However, as the solution pH became lower, the zeta potential of microbubbles changed from negative to positive at the solution pH of 4.5. In addition to the hydrophobic attraction, the electrostatic attraction between oil droplets and microbubbles was generated since the zeta potentials of droplets and microbubbles had negative and positive values, respectively.

Behaviour of whey protein emulsion gel during oral and gastric digestion: effect of droplet size.

A set of whey protein stabilized-emulsion gels with different droplet size distributions (D4,3 = ∼1, 6 and 12 μm) was produced, and the mechanical properties of the gels in the linear viscoelastic region and at large deformation were measured, along with the physicochemical and structural changes of the gels during oral mastication and gastric digestion. The gels containing 1 μm oil droplets had an aggregated particle structure with proteins coating at oil droplets whereas the gels containing 12 μm oil droplets had a particle-filled structure with spatially continuous matrix. During oral processing, the release of oil droplets from the gels increased as the droplet size increased, with coalescence being seen in gels containing oil droplets of 6 and 12 μm diameter. Under gastric digestion, high degrees of coalescence and phase separation of oil droplets occurred in the gels containing 6 and 12 μm oil droplets because of oil droplet release from the gel matrix; this led to slow gastric emptying. The gels were finally broken down into peptide aggregates and oil droplets (or free oil). The gels, containing 1 μm oil droplets disintegrated into various particles of several to several tens of microns with a low degree of oil droplet release and coalescence. Protein breakdown was slower in these gels, suggesting that the protein structures of the gel matrices were affected by the sizes of the incorporated oil droplets.

Flocculation and Separation of Oil Droplets in Ultrasonic Standing Wave Field

A new method for breaking oil in water emulsion based on flocculation of droplets in high intensity ultrasonic standing wave field was developed in this study and the effect of initial droplets size, type of disperse phase as well as the time of sonication and the height of emulsion in the chamber on the extent of interdroplet interactions were investigated. The results showed that type of disperse phase affects the efficiency of separation process through controlling the initial size of droplets. For the two types of disperse phase in question the efficiency of separation was calculated to be 42.7% for canola oil/water emulsion and 37% for sunflower oil/water emulsion. The time of sonication was found to have a positive contribution to the percent of flocculation and coalescence, so that the largest aggregates were formed after 30 minutes treatment. Also, the optimum height of emulsion in the treatment chamber was determined to be λ/4 at which the strongest flocculation and highest percent of coalescence took place. Increasing the height of emulsion did not significantly influence the course of aggregation and separation.