AU2013204066A1

AU2013204066A1 - Methods for isolating oil from plant material and for improving separation efficiency

Info

Publication number: AU2013204066A1
Application number: AU2013204066A
Authority: AU
Inventors: Warwick Bagnall; Darren M. Bates
Original assignee: Cavitus Pty Ltd
Current assignee: Cavitus Pty Ltd
Priority date: 2012-08-07
Filing date: 2013-04-11
Publication date: 2014-02-27
Also published as: CO7180033A1

Abstract

METHODS FOR ISOLATING OIL FROM PLANT MATERIAL AND FOR IMPROVING SEPARATION EFFICIENCY The present invention relates to method of isolating oil from plant material, comprising: a) generating cavitation bubbles within said plant material or a composition comprising said plant material, and b) collapsing said cavitation bubbles; wherein high velocity micro liquid streaming is produced within said plant material or composition comprising said plant material on collapse of said cavitation bubbles, and wherein said high velocity micro liquid streaming assists in isolation of oil from said plant material. The invention also relates to methods for enhancing coalescence of oil droplets or oil/water emulsion separation, comprising exposing said oil droplets or oil/water emulsion to low frequency wave energy. The present invention also relates to the recovery of emulsified triglycerides from any dilute oil-containing liquid using a series of steps including optional cavitation treatment, non-oil solids removal, oil concentration and coalescence.

Description

1 METHODS FOR ISOLATING OIL FROM PLANT MATERIAL AND FOR IMPROVING SEPARATION EFFICIENCY FIELD [001] The present invention relates to isolation of organic oils from plant source materials (utilizing liquids such as water, ethanol, hexane or, in certain cases, no additional liquid), as well as coalescence of isolated oil droplets or separation of oil/water emulsions to improve separation efficiency of the oils in a centrifuge, cyclone or decanter. The invention also relates to methods for the extraction of oil from dilute emulsions and waste streams. It more specifically relates to the concentration and coagulation of emulsified oil in dilute streams with the aim of recovering the oil. BACKGROUND [002] The use of oils from plant materials in food preparation as well as personal care products such as soap and wound treatments has been around for well over a hundred years. While small, relatively primitive batch methods have historically been the main source of natural oil production, more recently oil extraction has evolved into large-scale continuous processing. [003] In particular, palm oil generated during the processing of the palm mash from the fruit of the palm contains large amounts of solid (fiber) and liquid materials (oil and water). Typically, the recovery of oil is done with a conventional mechanical press. However, a significant amount of oil is retained in the pressed fibers, and this is not recovered by conventional centrifuge and decanter processes in a palm oil mill. As a result, fibers and plant material still containing oil end up passing through palm mill processes and into waste treatment plants. [004] Many attempts have been made to address this problem, including mechanical treatments such as various filter systems, and chemical treatments, for example, enzymatic treatments. However, these treatments can be either quite complicated or expensive to carry out, or very time consuming, either or all of which can work against a successful operation of any commercial scale, especially in the remote locations where most of this processing takes place. [005] In addition to oil associating with solids and/or fibrous materials, liquid streams with oil concentration less than or equal to 10% are also often formed during oil extraction. The oil in these streams is usually a mixture of emulsified oil and oil still 2 bound within substrate cells and as such is difficult and expensive to extract by conventional methods such as gravity settling, centrifuging, coagulation, flocculation and flotation. [006] Examples of dilute streams containing emulsified oil are the clarifier underflow and palm mill effluent from the palm milling process, skim pit waste from the soybean solvent extraction process and freshly harvested algae grown in open ponds. [0071 The above streams have resisted attempts to recover oil in an economical, industrial-scale manner for many years. For example the palm milling industry's best practice is to discharge to the cooling ponds a mill effluent stream containing at least 0.3% oil. Another example is the production of algae for triglyceride extraction which in some cases produces a stream containing 1000ppm of algae, trapped inside which is oil that must be recovered. To date, economic recovery of oil from algae has severely restricted the economics of this industry. [008] Recovery using strong acids such as sulfuric acid to break the oil emulsion is known. However this recovery method hydrolyses the oil recovered, hence degrading its value. [009] Many non-conventional methods have also been tried but have never been commercialized due to their impractical or expensive nature. These include incline plate separators, enzymes which degrade the cellular matter to release the oil, flotation using coagulant and flocculant additives. [0010] Despite the above attempts there remains a strong demand for a practical method to recover oil from these liquid streams without degrading the oil quality. [0011] An object of the present invention is therefore to provide improved processes for isolating oil from plant material/fibers more efficiently. [0012] Another object of the present invention is to provide methods for coalescing oil droplets and/or to separate oil/water emulsions to improve the efficiency of classic separation methods, especially such methods as used in a palm oil mill such as centrifugation, decantation or filtration. [0013] Another object of the invention is to provide an improved method for separating triglyceride oil from any liquid stream containing emulsified or substrate bound oil at low concentrations.

3 SUMMARY [00141 The present invention is based on the finding that significant improvements can be obtained in the efficiency of oil isolation from plant materials by employing high velocity micro liquid streaming within the plant material or composition comprising it. [0015] Thus, according to a first embodiment of the invention, there is provided a method of isolating oil from plant material, said method comprising a) generating cavitation bubbles within said plant material or a composition comprising said plant material, and b) collapsing said cavitation bubbles wherein high velocity micro liquid streaming is produced within said plant material or composition comprising said plant material on collapse of said cavitation bubbles, and wherein said high velocity micro liquid streaming assists in isolation of oil from said plant material. [0016] In the course of these studies, improvements in oil isolation efficiency have also been found to be obtained by employing low frequency wave energy, which assists in coalescing oil droplets, including microscopic oil droplets in oil/water emulsions, thereby separating the oil and water phases more effectively. [00171 Thus, according to a second embodiment of the invention, there is provided a method for enhancing coalescence of oil droplets or enhancing oil/water emulsion separation, said method comprising exposing said oil droplets or oil/water emulsion to low frequency wave energy. [0018] Methods according to either embodiment of the invention may be carried out at one or more of the following stages in plant oil extraction: prior to conventional mechanical pressing of palm mash; on fibre stream material obtained after conventional mechanical pressing of palm oil mash; on liquid stream material obtained after conventional mechanical pressing of palm oil mash; on liquid stream material after screening; on solids stream material after screening; or on liquid or solids stream material obtained before or after decantation or centrifugation. [0019] According to a further embodiment of the invention, a method for isolating oil from plant material may comprise a method according to the first embodiment combined with a method according to the second embodiment, 4 [00201 According to a third embodiment of the invention, there is provided a method for recovering oil from a dilute oil-containing liquid mixture, said method comprising non-oil solids reduction and concentration of the oil fraction in said liquid mixture. [0021] According to an embodiment, concentration of the oil comprises foam fractionation or flotation to produce a concentrated emulsion, and coalescence of oil in said concentrated emulsion. According to an embodiment, concentration of the oil comprises sonic or ultrasonic coalescence. [0022] Coalescence may be effected by a number of methods, including heating, stirring, churning, use of chemical additives or sonic or ultrasonic splitting. According to an embodiment, the coalescence is effected by a method according to the second embodiment. [0023] Coalescence of oil in the liquid mixture may also be achieved directly by sonic or ultrasonic coalescence, Thus, according to another embodiment, concentration of the oil comprises sonic or ultrasonic coalescence. [0024] According to another embodiment of the present invention, a method according to the third embodiment is carried out in combination with a method according to the first embodiment. BRIEF DESCRIPTION OF THE DRAWINGS [0025] Figure 1 shows a flow chart for palm oil processing according to an embodiment of the present invention. The chart shows different positions in the process where cavitation system(s) and the coalescence system(s) may be employed. [0026] Figure 2 shows a flow chart for olive oil processing according to an embodiment of the present invention. The chart shows different positions in the process where cavitation system(s) and the coalescence system(s) may be employed. [00271 Figure 3 shows a flow chart of a coalescence process according to the invention. Such a process may be implemented in embodiments as illustrated in Figure 1 or Figure 2.

DEFINITIONS

5 [00281 The term "comprising" means including principally, but not necessarily solely. Furthermore, variations of the word "comprising", such as "comprise" and "comprises", have correspondingly varied meanings. [0029] As used in this application, the singular form "a", "an" and "the" include plural references unless the context clearly dictates otherwise. For example, the term "a surface" also includes a plurality of surfaces. [0030] As used herein, the term "concentration", in the context of isolation of oil from liquid mixtures comprising low levels of oil, means increasing the amount of oil per volumetric measurement relative to the immediate surroundings of the oil. The oil may still be in contact with the remaining liquid/aqueous phase, but is present as, or in a separate phase which may be an oil phase, emulsion or microemulsion which has not been physically separated from the liquid/aqueous phase. Variations of the word "concentration", such as "concentrate" and "concentrating", have correspondingly varied meanings. [0031] As used herein, the term "high velocity micro liquid streaming" refers to very high velocity liquid forces (liquid streams on a microscopic level travelling at speeds of up to 10OOkm/hr or more). Such high velocity liquid forces are produced, for example, when cavitation bubbles collapse, releasing the internal energy of the cavitation bubbles. [0032] As used herein, the term "specific energy" refers to the energy consumed by an ultrasonic system, and the average specific energy means the total specific energy applied to the fluid divided by the total volume of the fluid (in litres). DETAILED DESCRIPTION [0033] The present invention is based in part on the finding that high velocity micro liquid streaming, created when cavitation bubbles collapse within a liquid, cause oils to be separated from cellular materials more easily, efficiently and quickly, thereby resulting in improved yields of oils from plant materials. In the course of the present studies, it has also been found that further improvements in efficiencies of isolation of oils from plant material can be obtained by applying low frequency wave energy to liquids isolated from plant materials, which low frequency wave energy causes the agglomeration and re coalescence of oil droplets, and separation of emulsions into oil and water phases. It has further been found that improved separation of oil from liquid waste streams may be executed by removal of insoluble non-oil material followed by concentration and removal 6 of the oil by a method utilizing the surfactant properties of the oil droplets, which is followed by coalescence of the concentrated oil. Cavitation Energy and Sources [0034] The mechanism of the cavitation energy treatment is based on the creation of small high energy cavitation bubbles which form and have a life time of less than 1 second. During the formation of the high energy cavitation bubbles, the internal energy level becomes very high. Temperatures of up to 5,000'C and pressures of 1000-2000 bar may be achieved. The size of cavitation bubbles will reach about 0.5pm to about 100pm in size. Millions of cavitation bubbles are created each second in the chamber of a cavitation device. [00351 The bubbles are formed either in the oil or water component of the palm oil mash fiber mix. The cavitation can occur in the liquid, which is externally bound to the fiber material or in liquids which are internally bound to the fiber. When cavitation bubbles collapse, internal energy is released in the form of very high velocity liquid forces (liquid streams on a microscopic level travelling at speeds of up to 1000km/hr or more, and is known as microscopic high velocity streaming). These high velocity forces cause oil to be separated and isolated more easily, efficiently and quickly from the cellular fibers and cell walls resulting in increased oil removal. [00361 The cavitation is created by an oscillating or vibrating surface which is inserted directly into the plant material slurry or mash. The surface may oscillate/vibrate at a frequency greater than 15,000Hz, and may oscillate in the range of from about 16,000Hz to about 50,000Hz, such as from about 16,000Hz to about 30,000Hz, from about 16,000Hz to about 25,000Hz, from about 16,000Hz to about 23,000Hz, from about 16,000Hz to about 21,000Hz, from about 16,000Hz to about 19,000Hz, from about 16,000Hz to about 18,000Hz, from about 17,000Hz to about 25,000Hz, from about 17,000Hz to about 23,000Hz, from about 17,000Hz to about 21,000Hz, from about 17,000Hz to about 19,000Hz, from about 18,000Hz to about 25,000Hz, from about 18,000Hz to about 23,000Hz, from about 18,000Hz to about 21,000Hz, about 16,000Hz, about 17,000Hz, about 18,000Hz, about 19,000Hz, about 20,000Hz, about 21,000Hz, about 22,000Hz, about 23,000Hz, about 24,000Hz, or about 25,000Hz. [00371 The size of the oscillation can be between about 0.1gm and about 150gm, such as from about 0.1gm and about 100gm, from about 0.1gm and about 50gm, from 7 about 1pm and about 25pm, about 5gm, about 10gm, about 15gm, about 20gm, or about 25pm. [0038] The cavitation energy may be applied to the reaction mixture at an average specific energy of between about 1x10- 9 kWh and about 1kWh energy per litre reaction mixture, such as between about 1x10-7kWh and 1kWh energy per litre reaction mixture, between about 1x10-5kWh and 1kWh energy per litre reaction mixture, between about 1x10-4kWh and 1kWh energy per litre reaction mixture, between about 1x10-3kWh and 1kWh energy per litre reaction mixture, between about 1x10-2kWh and 1kWh energy per litre reaction mixture, between about 1x10- 9 kWh and 1x10-1kWh energy per litre reaction mixture, between about 1x10-7kWh and 1x10-'kWh energy per litre reaction mixture, between about 1x10-5kWh and 1x10-IkWh energy per litre reaction mixture, between about 1x10-4kWh and 1x10-'kWh energy per litre reaction mixture, between about 1x10 3 kWh and 1x10- kWh energy per litre reaction mixture, between about 1x10-7kWh and 1x10-2kWh energy per litre reaction mixture, between about 1x10-6kWh and 1x10-2kWh energy per litre reaction mixture, between about 2x-5kWh and about 1x10-2kWh energy per litre reaction mixture, between about 1 1-4 kWh and about 1 1-2 kWh energy per litre reaction mixture, between about 1x10-3kWh and about 1x0-2kWh energy per litre reaction mixture, between about 1x0-7kWh and about 1x0-3kWh energy per litre reaction mixture, between about 1x10-6kWh and about 1x10-3kWh energy per litre reaction mixture, between about 1x10-5kWh and about 1x10-3kWh energy per litre reaction mixture, between about 1x10-4kWh and about 1x10-3kWh energy per litre reaction mixture, between about 1x10-5kWh and about 1x10-2kWh energy per litre reaction mixture, between about 1x10-5kWh and about 1x10-2kWh energy per litre reaction mixture, about 1kWh energy per litre reaction mixture, about 5x0-IkWh energy per litre reaction mixture, about 1 x10- 1kWh energy per litre reaction mixture, about 5x10-2kWh energy per litre reaction mixture, about 1x0-2kWh energy per litre reaction mixture, about 5x10-3kWh energy per litre reaction mixture, about 1x10-3kWh energy per litre reaction mixture, about 5x10-4kWh energy per litre reaction mixture, about 1x10 4 kWh energy per litre reaction mixture, or about 1x10-5kWh energy per litre reaction mixture. [00391 The energy intensity applied to the reaction mixture may range from about 0.00001W/cm 2 to about 1000W/cm 2 , such as from about 0.00 1W/cm 2 to about 1000W/cm 2 , from about 1W/cm 2 to about 1000W/cm 2 , from about 10W/cm 2 to about 8 1000W/cm 2, from about 100W/cm2 to about 1000W/cm2, from about 500W/cm2 to about 1000W/cm 2 , from about 0.0 W/cm 2 to about 500W/cm 2 , from about 1W/cm2 to about 500W/cm 2 , from about 01W/cm 2 to about 500W/cm 2 , from about 1W/cm 2 to about 500W/cm 2 , from about 250W/cm 2 to about 500W/cm 2 , from about 1.001W/cm 2 to about 250W/cm 2 , from about 1W/cm 2 to about 250W/cm 2 , from about 0 W/cm 2 to about 250W/cm 2 , from about 100W/cm 2 to about 250W/cm 2 , from about 0.00W/cm 2 to about 00W/cm 2 , from about 1W/cm 2 to about 0W/cm 2 , from about 10W/cm 2 to 100W/cm 2 , from about 0.001W/cm 2 to about 10W/cm 2 , from about 0.5 W/cm 2 to 10W/cm 2 , from about 1W/cm 2 to about 10W/cm 2 , or from about 5W/cm 2 to 10W/cm 2 , about 1W/cm 2 , about 5W/cm 2 , about 10W/cm 2 , about 25W/cm 2 , about 50W/cm 2 , about 75W/cm 2 , about 100W/cm 2 , about 250W/cm 2 , about 500W/cm 2 , about 750W/cm 2 , or about 1000W/cm 2 . [0040] The speed of microstreaming effects (high velocity liquid) from collapsing cavitation bubbles may be in the range of from about 500 km/hr to about 1200km/hr, such as from about 500 km/hr to about 1OOOkm/hr, or from about 700 km/hr to about 1 OOOkm/hr. [0041] The cavitation effect can be further enhanced by inserting the oscillating surface into a high pressure orifice. The oscillating surface can be applied directly to the plant material slurry either in a tank or vessel or in a flow through chamber or pipe. [0042] The cavitation energy could also be applied either directly to a plant/oil mash or in combination with additional liquid solvents such as water, ethanol, ethanol/water mix, hexane, methylene chloride or other liquid solvents. [0043] Cavitation can be generated from a multitude of devices such as rotating devices, pumps or higher pressure pumps, vibrating piston blades, acoustic devices or devices oscillating or vibrating in the ultrasonic range. According to an embodiment cavitation is generated by ultrasonic energy emitted by a transducer. [0044] Ultrasonic apparatus (comprising transducers, sonotrodes or probes, and boosters) for use in processes of the invention are commercially available. Typical ultrasonics set-ups comprise a transducer, and optionally a booster, and one or more ultrasonic probes/sonotrodes. A transducer useful in processes of the invention may deliver a power range of up to 1000 W/cm 3. A transducer transforms electrical energy into vibrational (oscillatory) energy, and may deliver this directly to a fluid or indirectly via a probe or sonotrode.

9 [00451 According to an embodiment of the invention, ultrasonic energy is transferred indirectly into a reaction mixture via a suitable medium (water, oil, or other organic or inorganic fluid) through the walls of a flow cell and into the reaction mixture. [0046] One or more transducers may be connected to, for example, the outside of a flow cell or tube (made of suitable material) making the flow cell or tube ultrasonically active. Transducers can be connected to the flow cell or tube by any suitable known means. For example, transducers may be welded to, or screwed into the flow cell, or be connected to the flow cell or tube by strap. [00471 According to another embodiment a sonotrode connected to a transducer, optionally via a booster, can be directly in touch with a reaction mixture and transfer ultrasonic energy directly into the mixture via the sonotrode (or probe) surface which is in direct contact with the reaction mixture. [00481 Ultrasonic probes (sonotrodes) can vary, delivering ultrasonic energy axially, radially (typically being cylindrical with a conical tip of decreasing diameter, typically at a 90 degree angle), or in a focused manner (having a flat tip), as sinusoidal or square wave emission or standing wave - (sonotrodes typically being comprised of one or more flat sonotrode plates which could be in single array or opposing plates). According to an embodiment, a sonotrode for use in processes of the present invention emits ultrasonic energy radially. [0049] According to an embodiment, the ultrasonic energy is highly propagating ultrasonic energy. A sonotrode generates ultrasonic energy typically when an alternating voltage is applied across a ceramic or piezoelectric crystalline material (PZT). The alternating voltage is applied at a desired oscillation frequency to induce movement of the PZT. The PZT transducer is mechanically coupled to the horn means which amplifies the motion of the PZT. The horn means includes a tip portion, which is a sonotrode. The assembly of the PZT horn means including the tip portion may also be referred to herein as the sonotrode. Highly propagating ultrasonic energy or HPU includes ultrasonic energy that is emitted substantially orthogonal to the axial direction of a sonotrode. Such energy propagates through a fluid medium, typically water or a gas and over a large distance from the sonotrode and is not limited to the areas immediately surrounding the sonotrode. After propagating through the medium the highly propagating ultrasonic energy may be applied over a surface and to penetrate into said surface.

10 [0050] Highly propagating ultrasonic energy waves are able to propagate through a viscous product up to a distance of at least 50cm to about 300cm, or about 100cm to about 300cm or about 150cm to about 300cm or about 200cm to about 300cm to a contaminated surface. Highly propagating ultrasonic energy propagates substantially uniformly across volumes and are able to penetrate up to up to a depth of about 0.000 1 1mm, or about 1-20mm, or up to a depth of about 2-20mm or up to a depth of about 5 20mm or up to about 5-15mm or up to about 7-10mm into substantially solid, porous or colloidal components of a material. [0051] In one embodiment of the present invention a combination of the high power, low frequency, long wavelength and sonotrode shape/design allows for the above effects to take place. In contrast, ultrasonic energy emitted from conventional ultrasonic cleaners has limited propagation distance from the emitting surface with a drop in energy of 90+ % at a distance of 100 cm and are not uniform in their volume area or volume of the treated flow stream, and do not have the ability to penetrate into solid, porous or colloidal components of a material. [0052] In another embodiment the sonotrode may be arranged such that the highly propagating ultrasonic energy generated is able to propagate through a material up to a distance of about 50cm to about 300cm, or about 100cm to about 300cm or about 150cm to about 300cm or about 200cm to about 300cm to the inner surface of a flow cell, conduit, vessel containing the material, transmit uniformly throughout the whole volume leaving no single space/zone untouched from the wave energy. In addition, the highly propagating radial waves are able to penetrate up to about 5-20mm or up to about 5 15mm or up to about 7-10mm or into solid, porous or colloidal components of suspended in the material. [0053] In yet another embodiment, the highly propagating ultrasonic energy is emitted substantially at a right angle from the surface of a sonotrode with high energy. In this context high energy refers to a less than about 20% drop in energy and production of shear forces resulting from collapsing cavitation bubbles at a distance of about 100 to about 300cm from the emitting sonotrode. Furthermore, in this context high energy refers to the ability of the highly propagating ultrasonic energy to propagate into solid, porous or colloidal components of a material and create cavitation internally up to a depth of about 0.0001-1mm, or about1-20mm, or up to a depth of about 2-20mm or up to a depth of about 5-20mm or up to about 5-15mm or up to about 7-10mm.

11 [00541 In one embodiment the amplitude of the highly propagating ultrasonic energy is between about 0.001 to about 500 microns, preferably between about 0.01 to about 40 microns amplitude, more preferably between about 0.01 to about 20 microns, even more preferably between about 1 to about 10 microns. [0055] In a further embodiment the highly propagating ultrasonic energy is applied to a flowable material or fluid over a period of time from about 0.00 1 second to about 60 minutes, such as from about 0.001 second to about 50 minutes, from about 10 seconds to about 40 minutes, from about 15 seconds to about 40 minutes, from about 20 seconds to about 30 minutes, from about 25 seconds to about 20 minutes, from about 30 seconds to about 10 minutes, from about 30 seconds to about 2 minutes, from about 0.00 1 second to about 1 minute, from about 0.001 second to about 10 seconds, from about 0.001 second to about 1 second, from about 0.001 second to about 0.1 second, or from about 0.001 second to about 0.01 second. [0056] The vibrating surface creating cavitation in the reaction mixture may be made of any suitable material, such as steel, titanium, hastalloy, or nickel titanium alloy. According to an embodiment the surface is made of steel. [00571 While a number of sonotrode-transducer arrangements which can be used to subject reaction mixtures to ultrasonic energy are available, typically a transducer is connected to a sonotrode via a booster. A booster assists in controlling (boosting up or down) the energy delivered to a sonotrode. A reaction mixture is typically passed by a sonotrode directly, although any flow through arrangement is contemplated that ensures that the reaction mixture is contacted with ultrasonic vibrations to rupture cell material or separate oil from fibrous or other plant material. Low Frequency Sound Waves and Sources [0058] Systems for coalescence of oil droplets and separation of oil/water emulsions is based on using low frequency sound waves having frequencies below 15,000Hz, such as between about 500Hz and about 15,000Hz, between about 500Hz and about 10,000Hz, between about 500Hz and about 5,000Hz, between about 500Hz and about 3,000Hz, between about 500Hz and about 2,000Hz, between about 500Hz and about 1,000Hz, between about 700Hz and about 5,000Hz, between about 700Hz and about 3,000Hz, between about 700Hz and about 2,000Hz, between about 700Hz and about 1,500Hz, or between about 700Hz and 1,200Hz, about 250Hz, about 500Hz, about 12 600Hz, about 700Hz, about 800Hz, about 900Hz, about 1000Hz, about 1200Hz, about 1500Hz, about 2000Hz, about 3000Hz, about 4000Hz, or about 5000Hz. [0059] A system for generating low frequency wave energy may comprise a generator, a transducer, and a sonotrode plate. [0060] The generator sends an electrical signal to the transducer, the transducer converts electrical energy into mechanical vibration between 500Hz and 15kHz, and the vibration is emitted into a fluid medium via a square or rectangular sonotrode plate or block. The plates may be connected directly into the fluid medium or built into a flow chamber or tube. [0061] One or more transducers may be connected to, for example, the outside of a flow cell or tube (made of suitable material) making the flow cell or tube acoustically active. Transducers can be connected to the flow cell or tube by any suitable known means. For example, transducers may be welded to, or screwed into the flow cell, or be connected to the flow cell or tube by strap. [0062] Acoustic sonotrodes can vary, delivering vibration energy axially or radially, as sinusoidal or square wave emission or standing wave - (sonotrodes typically being comprised of one or more flat sonotrode plates which could be in single array or opposing plates). According to an embodiment, a sonotrode for use in processes of the present invention emits acoustic energy and vibration radially. [0063] The vibrating plates in the reaction mixture may be made of any suitable material, such as steel, titanium, hastalloy, or nickel titanium alloy. According to an embodiment the surface is made of steel. [0064] The plates are vibrated at frequencies between 500Hz and 15kHz vibrational energy at this frequency creates forces which cause the agglomeration and re coalescence of like molecules such as oil. This results in very large oil droplets, which helps in the separation and isolation of oil phases from solids and other types of liquids such as water. This technique could also be used for other types of liquid separation processes as well as oil water emulsions. [0065] Processes according to the present invention may be employed to isolate oil from any desired plant material. According to certain embodiments, the plant material is selected from palm fruit, olive fruit, coconut fruit, soya bean, corn germ, canola seed, avocado fruit, nuts such as peanuts, citrus peel, grape seed, herbs (leaves, flowers, fruit, 13 seeds, stems, or roots) and tea tree leaves. According to another embodiment the plant material is selected from palm or olive fruit. [00661 According to an embodiment, a process according to the invention is for isolation of palm oil from palm fruit. [00671 According to another embodiment, a process according to the invention is for isolation of olive oil from olives. Palm Oil Isolation [0068] In palm oil processing, palm fruit are cut from the palm trees in bunches, and the bunches are collected and transported to the processing facilities. [0069] The bunches are then sterilized, typically with hot water or steam, which in addition to softening the fruit and causing some advantageous chemical breakdown in the fruit, has the added benefit of inactivating lipases (which hydrolyze fatty acid to glycerol ester linkages, releasing free fatty acids), and destroying any insects or other living creatures such as snakes present in the bunches. [00701 The fruit is then separated from the bunches, which can be done by hand, but is more typically done with mechanized threshers. The empty bunches or bunch waste can be further treated or burned for fuel or to produce ash for fertilizer. The next step in the process is digestion of the fruit. This is typically accomplished in heated vessels containing stirring arms or beaters. This part of the process releases the largest portion of the palm oil entrained in the fruit. [00711 In conventional palm oil processing, following digestion of the fruit, the digested mass is next moved to a press, resulting in a liquid stream, also known as the oil portion, and a solid or fibre stream. [0072] The fibre stream contains fibrous material, as well as the nut or kernel of the palm fruit, and also contains small amounts of palm oil. [00731 The liquid stream, in addition to containing substantial amounts of palm oil, also contains minor amounts of water (typically having been added in small volumes to increase the efficiency of the pressing process) and large amounts of cell debris, fibrous material and other non-oil solids. The liquid stream is passed through screens, and then clarified and separated into oil (or light) phase, and waste streams including solids and residual heavy/sludge streams.

14 [00741 According to the present invention, improvements in oil isolation or recovery may be achieved during digestion (or prior to pressing), and/or in further processing of the solids/waste streams obtained during conventional processing by treating the materials at these stages with cavitation energy and/or low frequency sound waves. According to an embodiment, a method of the present invention is carried out on a solids/waste stream, such as on fibre stream material obtained after conventional mechanical pressing of palm oil mash; on liquid stream material obtained after conventional mechanical pressing of palm oil mash; on liquid stream material after screening; on solids stream material after screening; or on liquid or solids stream material obtained before or after decantation or centrifugation [00751 Referring to Figure 1, cavitation energy may be applied in-line/continuously to the palm fruit mash stream before, in or after the digester as a pre-treatment to the press causing oil droplets to be removed and isolated from the cell/fiber material. Some of the oil droplets form an emulsion phase as a result of the cavitation treatment. [0076] Palm fruit mash treated with cavitation energy may also be passed through a second device, which may also form part of a cavitation/coalescence unit, and which emits low frequency sound waves causing oil droplets to coalesce and form larger oil droplets. Secondly any formed oil/water emulsion is separated into oil and water phases by the low frequency sound waves. [00771 The treated mash is then passed through a standard mechanical press. Because of the cavitation treatment and the low frequency sound wave treatment, the amount of oil recovered from the mechanical press is greater than that recovered by conventional methods not employing cavitation and/or low frequency sound waves. [0078] The presses can be either of the batch or continuous type, and may be screw, roller or hydraulic presses. Multiple presses can also be operated in parallel, emptying into a single container or holding tank. The press basically squeezes the palm oil out of the digested mass, creating a liquid portion stored in the holding tank) and a solids portion. [00791 As described above, the press fibre stream resulting from the pressing process also contains the nut or kernel of the palm fruit, and also contains small amounts of palm oil. This portion may be further treated with cavitation energy and/or low frequency sound waves to recover this residual amount of oil from the solid portion. Water may be added to the solid portion, which helps in the efficiency of the cavitation 15 energy treatment. Cavitation energy is applied in-line/continuously to the solid/water stream causing the oil droplets to be removed and isolated from the fibrous material. Some of the oil droplets form an emulsion phase as a result of the cavitation treatment. The oil, water and fibers may then be passed through a second device which emits low frequency sound waves causing the oil droplets to coalesce and form larger oil droplets, and causing any oil/water emulsion phases to be separated into separate oil and water phases. The stream is then passed through a standard screen filter, centrifuge and decanter where the large isolated oil droplets are recovered. [0080] As described above, the liquid stream resulting from the press process, generally referred to as the oil portion, in addition to containing substantial amounts of palm oil, also contains minor amounts of water (typically having been added in small volumes to increase the efficiency of the pressing process), and solids including cell debris, fibrous material and other non-oil solids. [0081] Cavitation energy may be applied in-line/continuously to the oil stream causing the oil droplets to be removed and isolated from the cell/fiber material. Some of the oil droplets may form an emulsion phase as a result of the cavitation treatment. The oil, water and fibers may then be passed through a second device which emits low frequency sound waves causing the oil droplets to coalesce and form larger oil droplets, and causing any oil/water emulsion phases to be separated into separate oil and water phases. The stream is then passed through a standard screen filter where solids are removed from the liquid stream. The separated solids typically comprise some associated oil, and may be recycled back to the digester stage for further processing. [0082] The liquid stream is then passed to clarification tanks (optionally after a further cavitation and/or low frequency wave energy treatment) to further separate the oil from residual impurities. At this point the clarified palm oil may be collected. [0083] The residual impurities (sludge stream) may be passed through a de-sanding stage and may be further processed with cavitation energy and/or low frequency wave energy to isolate oil from the residual fibres/impurities and then treated with low frequency sound waves to aid oil coalescence before going on to a conventional decanter (with the oil phase resulting from this step being returned to the clarifying step for further oil isolation). Liquid and/or solids streams obtained after screening or centrifugation may be further treated with cavitation energy and/or low frequency wave energy to isolate further residual oil from these streams.

16 [00841 Processes for isolating palm oil according to the present invention may be carried out at a temperature of between about 10 C and about 100 0 C, such as from about 30'C to about 100 0 C, from about 50'C to about 100 0 C, or from about 50'C to about 95 0 C. Olive Oil Isolation [0085] Olive oil processing typically involves washing/destemming of harvested olive fruit, grinding of the washed fruit (using, for example, stone mills, metal tooth grinders or hammermills), optionally passing this through a mixer (typically a malaxer, or thermal mixer), and then separating the oil from the rest of the olive components. [0086] Referring to Figure 2, following grinding of the olive fruit, further release of oil from the fibrous material and or remaining intact cells may be achieved by applying cavitation energy to the ground material. [00871 After this, and after an optional mixing/malaxer step, low frequency wave energy may be applied to the treated material, thereby causing the oil droplets to coalesce and form larger oil droplets, and causing any oil/water emulsion phases to be separated into separate oil and water phases. The stream may then be passed through a decanter screen filter and/or centrifuge where the large isolated oil droplets are recovered. [0088] Liquid and/or solids streams obtained after screening or centrifugation may be further treated with cavitation energy and/or low frequency wave energy to isolate further residual oil from these streams. [0089] Processes for isolating olive oil according to the present invention may be carried out at a temperature of between about 5 0 C and about 60 0 C, such as from about 5 0 C to about 50 0 C, from about 5 0 C to about 40 0 C, from about 10 0 C to about 30 0 C, from about 15 0 C to about 30 0 C, from about 15 0 C to about 25 0 C, from about 20 0 C to about 25 0 C, about 15 0 C, about 20 0 C, about 25 0 C, or about 30 0 C. [0090] Processes according to the invention can be run as batch processes, or as continuous processes. [0091] While water is the preferred medium/solvent for use in extraction of edible oils, other solvents may be used in processes of the invention, such as, for example, hexane, ethanol, water/ethanol mixes, methylene chloride or any other solvent suitable for use in extraction of oils or fats from biological tissues.

17 [00921 Cavitation energy treatment and/or low frequency coalescence treatment may be applied at one step only in a process for isolating oil from plant material, such as in a process as described above, or at a plurality of steps in such processes. Furthermore, cavitation treatment and low frequency coalescence treatment need not occur together at any given step in a process, or even occur together within a process of the invention. For example, a process for isolating oil from palm fruit may comprise a cavitation step for treatment of the solids portion after pressing only. A coalescence step after this may be included or omitted. Alternatively, a process for isolating oil from palm fruit may comprise a cavitation step for treatment of the digested fruit prior to pressing, and a coalescence step applied to the liquid obtained after pressing. Thus, any combination of cavitation and coalescence steps is contemplated in processes according to the invention. [0093] Cavitation and coalescence may be provided by separate units or combined units. Furthermore, the various process streams may be run through a plurality of cavitation units, coalescence units or combined cavitation/coalescence units in series, or as split streams in parallel, optionally with each split stream running through a series of such units. Recovery of Oil From Dilute Oil Sources [0094] There are numerous known methods for clarifying oil/triglyceride containing wastes in order to clarify the waste for disposal to wastewater such as gravity settling, addition of coagulant or flocculant chemicals, use of inclined plate settlers, centrifugation and flotation. Whilst these methods are known to reduce the oil content of the waste, they typically produce an oil-containing waste, which contains significant amounts of non-oil solids (NOS) and is too dilute in oil to allow the oil to be recovered and separated from the water in the waste. Hence these methods are unsuitable for situations where the recovery of oils, rather than clarification of waste, is desirable. Such wastes may contain up to 10% v/v oil. [0095] Similarly, the use of methods such as foam fractionation to concentrate algal material for subsequent oil recovery is known. However, this material also contains significant amounts of NOS which must be removed later. This is usually accomplished through the expensive and hazardous process of solvent extraction or through centrifugation or gravity settling of the NOS from the coalesced oil. Unfortunately, removal of NOS by centrifugation or gravity settling from coalesced oil also reduces the yield of oil due to the adhesion of oil to the removed NOS particles.

18 [00961 The present invention is based in part on the finding that separation of oils from materials containing low oil levels (oil content of less than, or equal to 10%v/v, such as 9%v/v or less, 8%v/v or less, 7%v/v or less, 6%v/v or less, 5%v/v or less, 4%v/v or less, 3%v/v or less, 2%v/v or less, or 1 %v/v or less) is inhibited by interactions between the oil and non-oil insoluble particles in the streams. These interactions slow the rate of oil droplet rise in a manner similar to the phenomena of hindered settling. Hence removal of the NOS particles improves subsequent oil concentration and recovery processes. During the course of these studies, it has also been shown that removal of NOS particles at a step in the process where the oil concentration is low results in less oil loss with the removed NOS. [00971 An embodiment of the present invention is also based on the discovery that concentrated oil produced by NOS reduction and foam fractionation of dilute oil containing streams is much more easily agglomerated than both oil concentrated from high-NOS streams using foam fractionation and oil concentrated from low-NOS streams using methods other than foam fractionation. Without wishing to be limited by theory, one possible explanation for this is that the high surface area of the air-liquid interface during foam fractionation increases the rate of coalescence of the oil droplets by acting as a surface catalyst for droplet collisions. Removal of Non-Oil Solids [00981 According to an embodiment, and referring to Figure 3, separation of oil containing waste streams using methods which rely on the density of the particles within the stream conventionally splits the incoming stream into a light phase stream containing a higher concentration of mostly emulsified oil and a lower concentration of NOS, and a heavy phase containing a lower concentration of mostly encapsulated oil and non-oil solids. [0099] Numerous methods are known for this type of separation such as centrifugation, cyclones, spirals, clarifiers and settling tanks. [00100] In order to maximize the amount of light phase relative to heavy phase it is preferable to use a process which produces a condensed heavy phase with low water content such as process involving a decanter centrifuge. According to an embodiment, a two or three phase centrifuge or clarifier is used to create the light phase.

19 [00101] Where the source of the feed stream is a clarifier underflow in a conventional palm milling process, the final centrifuge in the conventional milling process is used to create the light phase in order to minimize capital expenditure. Thus, according to an embodiment, a two-phase decanter centrifuge is used to create the light phase. [00102] The waste material may be treated with cavitation in order to cause cell rupture in order to liberate trapped oil prior to separating the NOS from the light phase. In the course of the present studies it has been found that, if cavitation by ultrasound or other methods is applied to the material prior to non-oil solids reduction, such as to liquid prior to centrifuging, encapsulated oil will be freed and report to the light phase. Furthermore, in the case of palm mill streams, cavitation by ultrasound was found to increase the compactability of the NOS and hence decrease the amount of triglyceride containing liquid lost during NOS removal. [00103] Cavitation may be achieved by the use of any of the known cavitation methods such as ultrasound, pressure homogenization, pumping through a cavitation nozzle or static mixer or use of a dynamic mixer. According to an embodiment, the cavitation is created by a method as described earlier herein in the section titled "Cavitation Energy and Sources". According to another embodiment, the waste stream to be treated by cavitation is obtained as a result of separation of oil from material already treated with cavitation by a method as described earlier herein in the section titled "Cavitation Energy and Sources". According to an embodiment, ultrasound in the frequency range 15 to 25 kHz is used. According to another embodiment, the cavitation is created using a radial sonotrode. [00104] Another method that can be used to remove NOS prior to concentration is to add clean water to the top or middle of a foam bed in a foam fractionation process (see further below for further details) so as to reduce the concentration of NOS proceeding up the bed according to the method known in the mineral processing industry as froth washing. This method is advantageous as it allows the NOS removal and froth fractionation steps (to concentrate the oil) to be combined in a single, simple piece of equipment. [00105] Where froth washing is used the wash water superficial velocity can be anywhere between zero and 3 cm/s, such as between 0.001 and 2cm/s, between 0.001 and 1.5cm/s, between 0.001 and 1.Ocm/s, between 0.001 to 0.5 cm/s, about 0.05cm/s, about 20 0.lcm/s, about 0.2cm/s, about 0.3cm/s, about 0.5cm/s, about 1.0cm/s, about 1.5 cm/s, about 2.Ocm/s, or about 3.Ocm/s. [00106] After NOS removal the preferred NOS concentration of the material before concentration of the oil fraction should be less than 7%w/v, such as less than about 6%w/v, less than about 5%w/v, less than about 4%w/v, less than about 3%w/v, less than about 2%w/v, less than about 1%w/v, or less than about 0.5%. [001071 In some instances it may be preferable to exclude the solids removal step if the non-oil solids content of the recovered oil is below requirements without the use of an NOS removal step. Hence another embodiment of the invention is to exclude the solids removal step in the event that the NOS content of the recovered oil is acceptable without prior NOS removal. Concentration of Oil Emulsion [001081 The oil in the liquid mixture, once non-oil solids are reduced, can be concentrated prior to coalescence or, optionally, coalesced directly and separated as a non-emulsified stream by any method as already known in the art. Such methods may include, for example, foam fractionation or flotation, or coalescence using a sonic or ultrasonic splitter. [00109] Due to the quantity of material involved, it is desirable to concentrate the light phase emulsion prior to oil coalescence to minimize equipment and energy requirements. Furthermore, in the course of the present studies, it was found that oil coalesced more rapidly at higher concentrations. Hence concentration of oils in the mixture to as high a concentration as possible is desirable, preferably at least to 0.5%v/v, such as at least 1%v/v, at least 2%v/v, at least 3%v/v, at least 4%v/v, at least 5%v/v, at least 7%v/v, or at least 10 %v/v. [00110] Foam fractionation is a chemical process in which hydrophobic molecules are separated from a liquid using rising columns of foam or fine bubbles. Flotation is a similar process, in which hydrophobic molecules attach to the surface of bubbles which, in turn, rise to form a rising foam. Following bubble formation, the bubbles are allowed to spend some time in contact with the surrounding liquid before or whilst rising upward to arrive at the air/water interface. The accumulation of bubbles at the air/water interface produces a froth layer which moves upwards, carrying with it any particles adhered to or entrained with the bubbles. By allowing the froth layer to increase in depth the age of the bubbles at the top of the froth layer increases and the thickness of the water films 21 surrounding each bubble decreases as water drains downwards due to gravity. Hence the ratio of water to adsorbed material (in the case of this invention oil) may be decreased and a concentrate high in oil obtained by collecting aged foam. Hence either of the processes of foam fractionation or flotation is advantageous for concentrating the low concentrations of oil found in, for example, waste streams resulting from vegetable oil extraction, once non-oil solids have been reduced sufficiently. [00111] Any method of foam fractionation, or flotation, as known in the art is suitable for this purpose. However methods which produce the smallest gas bubbles possible were found to not only strip the greatest amount of oil from the liquid but also to produce the most stable foam for the purpose of fractionation. Hence, according to an embodiment of the invention, aeration is used in a foam fractionation, of flotation process, which produces a mean air bubble diameter of between about 0.5 microns and 2mm, such as between about 1 micron to about 2mm, between about 2 microns and 2mm, between about 5 microns to about 2mm, between about 10 microns and 2mm, between about 20 microns and 2mm, between about 30 microns and 2mm, between about 50 microns and 2mm, between about 100 microns and 2mm, between about 200 microns and 2mm, between about 300 microns and 2mm, between about 500 microns and 2mm, between about 5 microns and 1.5mm, between about 5 microns and 1mm, between about 5 microns and 700 microns, between about 5 microns and 500mm, between about 5 microns and 400 microns, between about 5 microns and 300 microns, between about 5 microns and 200 microns, between about 5 microns and 100 microns, about 5 microns, about 10 microns, about 20 microns, about 30 microns, about 50 microns, about 70 microns, about 100 microns, about 150 microns, about 200 microns, about 300 microns, or about 500 microns. [00112] In order to produce bubbles of the preferred size, a number of methods are available including mechanical air flotation, sparged air flotation, dissolved air flotation, induced air flotation or cavitation air flotation. All of these methods can be used to produce bubbles of the preferred size. However, according to an embodiment of the present invention, the air is added to the oil-containing stream under pressure by dissolved air flotation or by cavitation air flotation. Said air is added at a pressure of at least 2 Bar absolute and usually less than 20 bar absolute and is added in such a concentration as to form a void fraction of between 5 and 80% once depressurized into the flotation column.

22 [001131 According to the above methods of bubble formation the bubbles are formed by adding air to liquid at a concentration less than that at which the bubbles would tend to quickly coalesce into much larger bubbles. In all but the method of sparged and dissolved air flotation the bubbles are then sheared into smaller bubbles by the mechanical action of rotating blades (mechanical air flotation), passing through a nozzle (cavitation air flotation) or by a plunging jet (induced air cavitation). [00114] Conventionally a surfactant is added to facilitate frothing and facilitate adsorption of oil droplets to the gas bubbles. However, during the course of the present studies, it has been determined that most triglyceride-containing streams naturally contain surfactant compounds which make such additions unnecessary. Where surfactant addition is found to be required, any suitable froth forming agent as known in the art may be used. For example, such an agent may be selected from proteins, methyl iso-butyl carbinol or plant-based saponins. However, as the recovered oil is often used for edible purposes, a food grade frother such as soy protein or plant-based saponin is preferred. [00115] During the course of the present studies, it has also been determined that, when the triglyceride to be recovered contains a significant amount of solid fat at lower temperatures, and when the liquid is cooled prior to entering a foam fractionation device, then the rate of oil recovery is increased. Without wishing to be limited by theory, this is thought to be due not only to the increased gas supersaturation possible at lower temperatures, but also due to partial solidification of the oil which modifies its surface properties in favour of adsorption to the gas bubbles. [001161 Thus, according to another embodiment of the invention, oil in the liquid mixture is concentrated using froth fractionation where the gas is introduced in micron sized bubbles to the fractionation vessel or column, wherein the liquid from which oil is to be recovered is cooled to between 10 and 70'C, such as between 20 and 70'C, between 30 and 70'C, between 40 and 70'C, between 50 and 70'C, between 60 and 70'C, between 10 and 60'C, between 10 and 50'C, between 10 and 40'C, between 10 and 30'C, between 10 and 20'C, about 10 0 C, about 20'C, about 30'C, about 40'C, about 50'C, about 60'C, or about 70'C. [001171 In an alternative embodiment, concentration and coalescence of the oil is achieved using sonic or ultrasonic coalescence. Such means can be used to coalesce small oil drops, as described below, but as such are also effective in concentrating the oil (into a separate oil phase) at the same time. Thus, concentration and coalescence may be 23 achieved simultaneously using sonic or ultrasonic means as described below or by low frequency sonic means as described above under the heading "Low Frequency Sound Waves and Sources". Coalescence of Concentrated Emulsion [00118] The concentrated emulsion obtained by methods as described above can be coalesced and separated as a non-emulsified stream by any method as already known in the art. Such methods may include, for example, heating and stirring using a conventional clarifier, centrifugation, churning at low temperature in the manner of butter production, contact with an oleophilic surface in the form of a packed-bed coalescer, addition of coagulant or flocculant chemicals followed by splitting by pH adjustment, or heating or coalescence using a sonic splitter or ultrasonic splitter. [00119] Furthermore, the oil-depleted emulsion can be optionally recycled to the previous emulsion concentration step to recover further oil droplets for coalescence. [00120] According to an embodiment of the invention, coalescence is achieved using a sonic splitter at a frequency between 0.05kHz and 1MHz, such as from about 100Hz to about 1MHz, from about 200Hz to about 1MHz, from about 500Hz to about 1MHz, from about 1kHz to about 1MHz, from about 2kHz to about 1MHz, from about 5kHz to about 1MHz, from about 10kHz to about 1MHz, from about 20kHz to about 1MHz, from about 50kHz to about 1MHz, from about 1kHz to about 800kHz, from about 1kHz to about 600kHz, from about 1kHz to about 400kHz, from about 1kHz to about 200kHz, from about 1kHz to about 100kHz, from about 1kHz to about 50kHz, from about 1kHz to about 25kHz, about 1kHz, about 2kHz, about 5kHz, about 10kHz, about 20kHz, about 50kHz, about 100kHz, about 200kHz, or about 500kHz. According to an embodiment, the splitter is operated at a frequency between 1 kHz and 25 kHz. [00121] According to another embodiment, coalescence is achieved using ultrasonic energy at a frequency of from about 200kHz to about 2MHz, such as from about 200kHz to about 1.5MHz, from about 200kHz to about 1MHz, from about 200kHz to about 1MHz, from about 200kHz to about 800kHz, from about 200kHz to about 600kHz, from about 200kHz to about 400kHz, from about 300kHz to about 1MHz, from about 400kHz to about 1MHz, from about 500kHz to about 1MHz, from about 600kHz to about 1MHz, from about 800kHz to about 1MHz, about 200kHz, about 300kHz, about 400kHz, about 500kHz, about 600kHz, about 700kHz, about 800kHz, about 900kHz, or about 1MHz.

24 According to an embodiment, coalescence is achieved using ultrasonic energy at a frequency of from 600kHz to 1 MHz. [00122] According to another embodiment, coalescence of the oil droplets in the concentrated oil emulsion is achieved by a method as hereinbefore described under the heading "Low Frequency Sound Waves and Sources". [00123] According to another embodiment of the invention, coalescence of the oil droplets in the concentrated oil emulsion is achieved using a palm mill clarifier, where the concentrated emulsion is heated and gently agitated to cause coalescence. The emulsion may be heated to a temperature of between about 50 to about 100 C, such as between 60 and 100 C, between 70 and 100 C, between 80 and 100 C, between 90 and 100 C, between 80 and 95C, between 50 and 95C, between 50 and 90C, between 50 and 80C, between 50 and 70C, between 50 and 60C, about 50C, about 60C, about 70C, about 80C, about 90C, about 95C, or about 100C. [00124] According to another embodiment of the invention, coalescence of the oil droplets in the concentrated oil emulsion is achieved by stirring the emulsion vigorously in an agitated vessel to increase coalescence of the oil droplets, followed by settling in a quiescent vessel to allow the oil droplets to rise to the surface to form a continuous oil layer. [00125] According to another embodiment of the invention, during a palm milling process (for example, as described earlier), the concentrated emulsion is returned to the mill clarifier or centrifuge where coalescence is carried out in conjunction with existing oil-bearing streams. [00126] According to another embodiment of the invention, coalescence of the oil droplets in the concentrated oil emulsion is achieved by churning the concentrated emulsion at high shear rates at a temperature below which the oil phase has between 20 and 100% solid content, such as between about 20 and 90% solid content, between about 20 and 80% solid content, between about 20 and 70% solid content, between about 20 and 60% solid content, between about 20 and 50% solid content, between about 20 and 40% solid content, between about 20 and 30% solid content, between about 30 and 40% solid content, between about 30 and 100% solid content, between about 40 and 100% solid content, between about 50 and 100% solid content, between about 60 and 100% solid content, between about 70 and 100% solid content, between about 80 and 100% solid content, between about 90 and 100% solid content, about 20% solid content, about 3 0% 25 solid content, about 40% solid content, about 50% solid content, about 60% solid content, about 70% solid content, about 80% solid content, or about 90% solid content. Such a process is similar to malaxation as used in olive oil extraction. [001271 The present invention will now be further described in greater detail with reference to the following specific examples, which should not be construed as in any way limiting the scope of the invention. EXAMPLES Example 1 [00128] Samples from a palm mill were taken from various points in the palm oil process and taken to the laboratory for small scale experiments in a 1 litre vessel using a 10 second cavitation energy treatment followed by a 10 second low frequency wave energy treatment for aiding coalescence of the oil droplets. [00129] The cavitation energy system was single phase power, 4 amps, 220volts and two power settings of 50 and 180 watts. [00130] The low frequency wave energy system was single phase power, 4 amps, 220volts, power was kept constant at 100 watts but 4 frequencies were tested 500Hz, 900Hz, 1.5kHz and 10kHz. [00131] The samples were kept at 95'C which was identical to the temperature of the palm oil material in the plant. Samples from the palm mill process were as follows; I. An un-diluted palm oil mash (containing, by volume: 61% sludge solids/water and 39% oil) before conventional press treatment; II. A diluted palm oil slurry post press treatment (containing, by volume: 38% oil, 6% emulsion, 2 6 % water, 3 0% sludge solids); III. Fiber stream sample post press (containing, by weight: 62 % fiber, 35% water and 3% oil); IV. Sludge solids from the settling tank going to the decanter (containing, by volume: 8 1 % water, 12% solids, 7% oil); and V. Sludge solids post the decanter/centrifuge (containing, by weight: 99.1% solids, 0.9%oil).

26 [001321 Characterization of oil cell isolation and emulsification was achieved by microscopy. Oil extraction yield was determined by settling tests over a period of 2 hours (90'C) as well as centrifugation using a conventional lab centrifuge (5 min. standard spin test). After centrifugation the volume of the decanted oil was recorded. The results for the palm oil samples were as follows: I. An un-diluted palm oil mash (containing - by volume - 61% sludge solids and 39% oil) before conventional press treatment. 100mL samples (control mash and treated samples) were centrifuged and then the oil decanted. The results below show the % increase in oil isolated and recovered from the mash fiber as a result of the different treatment conditions compared to the untreated control. Cavitation treatment 180watts - 9% increase in centrifuged decanted oil. Cavitation treatment 50watts - 5% increase in centrifuged decanted oil. Coalescence unit 500Hz - 1% increase in centrifuged decanted oil. Coalescence unit 900Hz - 4% increase in centrifuged decanted oil. Coalescence unit 1.5kHz - 3% increase in centrifuged decanted oil. Coalescence unit 10kHz - 0% increase in centrifuged decanted oil. Cavitation treatment 180watts + coalescence treatment at 900Hz - 12% increase in centrifuged decanted oil. II. A diluted palm oil slurry (containing, by volume: 3 8 % oil, 6 % emulsion, 2 6 % water, 30% sludge solids) post press treatment. 1OOmL samples (control mash and treated samples) were centrifuged and then the oil decanted. The results below show the % increase in oil isolated and recovered from the fiber/water as a result of the different treatment conditions compared to the untreated control. Cavitation treatment 180watts - 3.9% increase in centrifuged decanted oil. Cavitation treatment 50watts - 2.8% increase in centrifuged decanted oil. Coalescence unit 500Hz - 0% increase in centrifuged decanted oil. Coalescence unit 900Hz - 3.5% increase in centrifuged decanted oil. Coalescence unit 1.5kHz - 3% increase in centrifuged decanted oil. Coalescence unit 10kHz - 0% increase in centrifuged decanted oil. Cavitation treatment 180watts + coalescence treatment at 900Hz - 4.2% increase in centrifuged decanted oil. III. Fiber stream sample post press (containing, by weight: 62 % fiber, 35% water and 3% oil). 100mL samples (control mash and treated samples) were centrifuged and 27 then the oil decanted. The results below show the % increase in oil isolated and recovered from the fiber/water as a result of the different treatment conditions compared to the untreated control. Cavitation treatment 180watts - 38% increase in centrifuged decanted oil. Cavitation treatment 50watts - 25% increase in centrifuged decanted oil. Coalescence unit 500Hz - 5% increase in centrifuged decanted oil. Coalescence unit 900Hz - 27% increase in centrifuged decanted oil. Coalescence unit 1.5kHz - 20% increase in centrifuged decanted oil. Coalescence unit 10kHz - 3% increase in centrifuged decanted oil. Cavitation treatment 180watts + coalescence treatment at 900Hz - 45% increase in centrifuged decanted oil. IV. Sludge solids from the settling tank going to the decanter (containing, by volume: 81% water, 12% solids, 7 % oil). 100mL samples of post settling tank (control mash and treated samples) were centrifuged and then the oil decanted. The results below show the % increase in oil isolated and recovered from the mash fiber as a result of the different treatment conditions compared to the untreated control. Cavitation treatment 180watts - 4.6% increase in centrifuged decanted oil. Cavitation treatment 50watts - 3% increase in centrifuged decanted oil. Coalescence unit 500Hz - 1% increase in centrifuged decanted oil. Coalescence unit 900Hz - 4% increase in centrifuged decanted oil. Coalescence unit 1.5kHz - 3

.

2 % increase in centrifuged decanted oil. Coalescence unit 10kHz - 1% increase in centrifuged decanted oil. Cavitation treatment 180watts + coalescence treatment at 900Hz - 5.6% increase in centrifuged decanted oil. V. Sludge solids post the decanter/centrifuge (containing, by weight: 99.1% solids, 0.9%oil). 1OOmL post decanter samples (control and treated samples) were centrifuged and then the oil decanted. The results below show the % increase in oil isolated and recovered from the post decanter fiber/water stream as a result of the different treatment conditions compared to the untreated control. Cavitation treatment 180watts - 11% increase in centrifuged decanted oil. Cavitation treatment 50watts - 7% increase in centrifuged decanted oil. Coalescence unit 500Hz - 1% increase in centrifuged decanted oil. Coalescence unit 900Hz - 9% increase in centrifuged decanted oil.

28 Coalescence unit 1.5kHz - 7% increase in centrifuged decanted oil. Coalescence unit 10kHz - 1% increase in centrifuged decanted oil. Cavitation treatment 180watts + coalescence treatment at 900Hz - 14% increase in centrifuged decanted oil. [00133] Depending on the type of sample from the palm oil plant, the treated samples showed an increase in isolated oil and additionally from re-coalescence effects. Example 2 [00134] A continuous flow cavitation system and continuous flow low frequency wave system was installed on 1 press line in a palm oil plant operating at a flow rate of 180L/min. The two units were installed on the line in series at different points in the palm oil process. [00135] 1 litre samples from the palm mill were taken from various points in the palm oil process and taken to the laboratory for analysis. [00136] The cavitation energy system was three phase power, 16 amps, 380volts and a power setting of 2,600 watts energy. [001371 The low frequency wave energy system was 3 phase power, 16 amps, 380volts, power was kept constant at 1500 watts at a frequency of 900Hz. [00138] The samples were kept at 95'C during the analysis, which was identical to the temperature of the palm oil material in the plant. Samples from the palm mill process were as follows; I. An un-diluted palm oil mash (containing, by volume: 61% sludge solids/water and 39% oil) before conventional press treatment; II. A diluted palm oil slurry post press treatment (containing, by volume: 38% oil, 6% emulsion, 26% water, 30% sludge solids); III. Fiber stream sample post press (containing, by weight: 62% fiber, 35% water and 3% oil); IV. Sludge solids from the settling tank going to the decanter (containing, by volume: 81 % water, 12% solids, 7% oil); and V. Sludge solids post the decanter/centrifuge (containing, by weight: 99.1% solids, 0.9%oil).

29 [001391 Characterization of oil cell isolation and emulsification was achieved by microscopy. Oil extraction yield was determined by centrifugation (95 C) using a conventional lab centrifuge (5 min. standard spin test). After centrifugation the volume of the decanted oil was recorded. The results for the palm oil samples were as follows: I. An undiluted palm oil mash (containing - by volume - 61% sludge solids and 39% oil) before conventional press treatment. 100mL samples (control mash and treated samples) were centrifuged and then the oil decanted. The results below show the % increase in oil isolated and recovered from the mash fiber as a result of the different treatment conditions compared to the untreated control. Cavitation treatment 2600watts - 8% increase in centrifuged decanted oil. Coalescence unit 900Hz - 5% increase in centrifuged decanted oil. Cavitation treatment 2600 watts + coalescence treatment at 900Hz - 14% increase in centrifuged decanted oil. II. A diluted palm oil slurry (containing, by volume: 38% oil, 6% emulsion, 26% water, 30% sludge solids) post press treatment. 100mL samples (control mash and treated samples) were centrifuged and then the oil decanted. The results below show the % increase in oil isolated and recovered from the fiber/water as a result of the different treatment conditions compared to the untreated control. Cavitation treatment 2600watts - 3.1 % increase in centrifuged decanted oil. Coalescence unit 900Hz - 3.0% increase in centrifuged decanted oil. Cavitation treatment 2600watts + coalescence treatment at 900Hz - 6.9% increase in centrifuged decanted oil. III. Fiber stream sample post press (containing, by weight: 62% fiber, 35% water and 3% oil). 100mL samples (control mash and treated samples) were centrifuged and then the oil decanted. The results below show the % increase in oil isolated and recovered from the fiber/water as a result of the different treatment conditions compared to the untreated control. Cavitation treatment 2600watts - 31 % increase in centrifuged decanted oil. Coalescence unit 900Hz - 3 0% increase in centrifuged decanted oil. Cavitation treatment 2600watts + coalescence treatment at 900Hz - 55% increase in centrifuged decanted oil.

30 IV. Sludge solids from the settling tank going to the decanter (containing, by volume: 81% water, 12% solids, 7% oil). 1OOmL samples of post settling tank (control mash and treated samples) were centrifuged and then the oil decanted. The results below show the % increase in oil isolated and recovered from the mash fiber as a result of the different treatment conditions compared to the untreated control. Cavitation treatment 2600watts - 4.10% increase in centrifuged decanted oil. Coalescence unit 900Hz - 4% increase in centrifuged decanted oil. Cavitation treatment 2600watts + coalescence treatment at 900Hz - 6.6% increase in centrifuged decanted oil. V. Sludge solids post the decanter/centrifuge (containing, by weight: 99.10% solids, 0.9%oil). 1OOmL post decanter samples (control and treated samples) were centrifuged and then the oil decanted. The results below show the % increase in oil isolated and recovered from the post decanter fiber/water stream as a result of the different treatment conditions compared to the untreated control. Cavitation treatment 2600watts - 9% increase in centrifuged decanted oil. Coalescence unit 900Hz - 8.5% increase in centrifuged decanted oil. Cavitation treatment 2600watts + coalescence treatment at 900Hz - 15.5% increase in centrifuged decanted oil. [00140] Depending on the type of sample from the palm oil plant, the treated samples showed an increase in isolated oil and additionally from re-coalescence effects. The energy input (in kWh/L) for improving oil recovery is also quite low (e.g., 1x10' to 1x10- 5 kWh/L) for both the cavitation system and the low frequency coalescence unit. Example 3 [00141] A continuous flow cavitation system was installed on 1 line between a hammer mill and a malaxer in an olive oil plant operating at a flow rate of 8 tonnes per hour (Figure 2 shows the olive oil production process). [00142] A continuous flow low frequency wave system for enhancing olive oil coalescence was installed after the Malaxer in the olive oil process. [00143] 1 litre samples from the palm mill were taken from the two different points in the olive oil process and taken to the laboratory for analysis.

31 [001441 The cavitation energy system was three phase power, 32 amps, 400volts and two power settings: 10,000 watts energy and 6,000 watts energy. [00145] The low frequency wave energy system was 3 phase power, 16 amps, 400volts, power was kept constant at 1500 watts at a frequency of 900Hz. [00146] The samples were kept at 20'C during the analysis, which was identical to the temperature of the olive oil material in the plant. Samples from the palm mill process were as follows; 1. An un-diluted olive oil mash (containing - by volume - 80% sludge solids/water and 20% oil) after conventional hammer mill treatment 2. Olive oil slurry (80% solids/water and 20% oil) post malaxer and before the decanter/centrifuge treatment [001471 The conventional process normally produces and is highly variable between 160-180kg of olive oil from 1 tonne of olive fruit. During testing, the conventional process produced 177kg of olive oil for that particular day in the operation. Some of the oil was left bound in the olive mash fibers and cells and was not recovered. Also, some of the oil was lost in the form of oil/water emulsion during the hammer milling stage and this reduced the efficiency of oil separation in the malaxer. The high velocity microstreaming effect from the cavitation unit was installed between the mill and the malaxer to enhance the isolation of oil from olive fibers and cells. The low frequency device was positioned after the malaxer to aid in the coalescence of olive oil droplets and to separate the oil water emulsion into an oil phase which resulted in improving the oil separation process in the down stream decanter and centrifuge. [00148] Characterization of oil cell isolation and emulsification was achieved by microscopy. Oil extraction yield was determined by centrifugation (20'C) using a conventional lab centrifuge (5 min. standard spin test). After centrifugation the volume of decanted oil was recorded. The results for the olive oil samples were as follows: [00149] An undiluted olive oil mash (containing, by volume: 80% sludge solids and 20% oil) before conventional mill treatment. 100mL samples (control mash and treated samples) were centrifuged and then the oil decanted. The results below show the % increase in oil isolated and recovered from the olive mash fiber as a result of the different 32 treatment conditions compared to the untreated control. Also shown is the amount of oil captured from 1 tonne of olive fruit. Conventional process captured from 1 ton of fruit: 177kg oil. Cavitation treatment 10,000watts - 4% increase in centrifuged decanted oil. Olive oil captured from 1 tonne of fruit: 185kg of oil. Cavitation treatment 6,000watts - 3% increase in centrifuged decanted oil. Olive oil captured from 1 tonne of fruit: 182kg of oil. Coalescence unit 900Hz - 4% increase in centrifuged decanted oil. Olive oil captured from 1 tonne of fruit: 185kg of oil. Cavitation treatment 10,000 watts + coalescence treatment at 900Hz - 8% increase in centrifuged decanted oil. Olive oil captured from 1 tonne of fruit: 190kg of oil. Example 4 [00150] Fresh palm mill effluent with oil content of 0.58% oil and non-oil solids (NOS) content of 3.3% was collected and sonicated using a 2kW 20kHz ultrasonic unit with a radially emitting sonotrode at a flow rate of 1OL/min. The resulting liquid was cooled to 50'C and centrifuged using a two-phase decanter to produce a light phase with oil content 0.47% and NOS content 0.9% plus a cake phase. The light phase was passed through a froth fractionation unit to produce a concentrate equal in volume to 4% of the feed material with an oil content of 4% plus a depleted phase containing 0.1% oil. The concentrate was heated to 90'C and gently agitated to produce an oil layer which was collected from the surface. Example 5 [00151] Palm mill clarifier underflow with an oil content of 4% and NOS of 6% was passed through a three-phase decanter centrifuge to produce an oil phase which was returned to the clarifier as per the conventional practice, a light phase containing 8% oil and 3% NOS plus a cake phase. The light phase was foam fractionated whilst hot using an eductor to introduce the air bubbles in a manner consistent with Induced Air Flotation. A concentrated emulsion containing 10% oil and 8% NOS was recovered, leaving a 33 depleted phase of 0.1% oil and 1% NOS. The concentrated phase was coalesced in a small mill clarifier at a temperature of 90'C and the resulting oil returned to the mill clarifier, leaving a depleted phase containing most of the NOS from the concentrated emulsion which was disposed of to the mill cooling ponds. Continuous operation of this system over a period of several days showed no increase in the oil content of the mill clarifier underflow, indicating that the emulsion concentrate returned to the mill clarifier was successfully coalesced. Example 6 [00152] A suspension of algae at a concentration of 1000ppm was sonicated according to the conditions in Experiment 1 then centrifuged using a 2-phase decanter to produce a light phase containing 31 Oppm of oil. The light phase was foam fractionated to produce a concentrate containing 5% oil which was then passed through a sonic coalescer operating at 5 kHz to produce a coalesced oil stream. [00153] It will be appreciated that, although specific embodiments of the invention have been described herein for the purpose of illustration, various modifications may be made without deviating from the spirit and scope of the invention as defined in the following claims.

Claims

1. A method of isolating oil from plant material, said method comprising a) generating cavitation bubbles within said plant material or a composition comprising said plant material, and b) collapsing said cavitation bubbles wherein high velocity micro liquid streaming is produced within said plant material or composition comprising said plant material on collapse of said cavitation bubbles, and wherein said high velocity micro liquid streaming assists in isolation of oil from said plant material.

2. The method of claim 1, wherein said plant material is selected from palm fruit, coconut fruit, olives, canola seeds, soya beans, corn kernels, avocado fruit, other fruits and nuts, herbs, citrus peel, tea tree leaves, or mash, cells or fibre of any of said materials.

3. The method of claim 2, wherein said plant material or composition comprising it comprises palm oil mash and said method is carried out at one or more of the following steps: prior to conventional mechanical pressing of palm mash; on fibre stream material obtained after conventional mechanical pressing of palm oil mash; on liquid stream material obtained after conventional mechanical pressing of palm oil mash; on liquid stream material after screening; on solids stream material after screening; or on liquid or solids stream material obtained before or after decantation or centrifugation.

4. The method of any one of claims 1 to 3, wherein said cavitation bubbles are generated by a surface oscillating or vibrating at between about 16kHz and about 50kHz.

5. The method of claim 4, wherein the amplitude of the oscillation or vibration is between about 0.1pm and 150 pim.

6. The method of claim 4 or claim 5, wherein said oscillations or vibrations are provided in a square wave pattern or a sinusoidal wave pattern.

7. The method of any one of claims 1 to 6, wherein said cavitation energy is applied to the reaction mixture at an average specific energy of between about 1x10-5kWh and about 10-1kWh energy per litre reaction mixture.

8. The method of any one of claims 1 to 6, wherein said cavitation energy is applied to the reaction mixture at an energy intensity of from about 0.001W/cm 2 to about 500W/cm 2 35

9. A method for enhancing coalescence of oil droplets or enhancing oil/water emulsion separation, said method comprising exposing said oil droplets or oil/water emulsion to low frequency wave energy.

10. The method of claim 9, wherein said low frequency wave energy has a frequency of between about 500Hz and about 15kHz.

11. The method of claim 9 or claim 10, wherein said low frequency wave energy is applied to said oil or oil/water emulsion in a flow through chamber or pipe or in a tank or vessel.

12. The method of any one of claims 9 to 11, wherein said oscillations or vibrations are provided in a square wave pattern or a sinusoidal wave pattern.

13. The method of any one of claims 9 to 12, wherein said oil is selected from palm oil, coconut oil, olive oil, canola oil, soya bean oil, corn oil, avocado oil, oil of other fruits and nuts, essential oils from herbs, citrus oil, or tea tree oil.

14. The method of claim 13, wherein said oil comprises palm oil and said method is carried out at one or more of the following steps: prior to conventional mechanical pressing of palm mash; on fibre stream material obtained after conventional mechanical pressing of palm oil mash; on liquid stream material obtained after conventional mechanical pressing of palm oil mash; on liquid stream material after screening; on solids stream material after screening; or on liquid or solids stream material obtained before or after decantation or centrifugation.

15. The method of any one of claims 9 to 14, which is applied in combination with a method according to any one of claims 1 to 8.

16. A method for recovering oil from a dilute oil-containing liquid mixture comprising non-oil solids, said method comprising non-oil solids (NOS) reduction followed by concentration of the oil fraction in the NOS-reduced liquid mixture.

17. A method according to claim 16 wherein the oil concentration in the liquid mixture is 10% or less.

18. The method of claim 16 or claim 17, wherein concentration of the oil comprises foam fractionation or flotation to produce a concentrated emulsion, and coalescence of oil in said concentrated emulsion.

19. A method according to claim 18 where the coalescence method includes heating, stirring, churning, chemical additives or sonic or ultrasonic splitting.

20. A method according to claim 19 where the coalescence method is heating and stirring. 36

21. A method according to claim 19 where the coalescence method is a method according to any one of claims 9 to 15.

22. A method according to claim 19 where the coalescence method is ultrasonic coalescence at a frequency between 16kHz and 1MHz.

23. The method of claim 16 or claim 17, wherein concentration of the oil comprises sonic or ultrasonic coalescence.

24. A method according to claim 23 wherein said coalescence is effected by a method according to any one of claims 9 to 15.

25. A method according to claim 23 wherein said coalescence is effected by ultrasonic coalescence at a frequency between 16kHz and 1MHz.

26. A method according to claim 25 where the non-oil solids are removed by centrifugation.

27. A method according to any one of claims 16 to 26 where the liquid mixture is treated with cavitation prior to or during said non-oil solids reduction.

28. A method according to claim 27 where the cavitation is created using ultrasound or hydrodynamic cavitation.

29. A method according to claim 28 where the frequency is between 15 and 25 kHz.

30. A method according to any one of claims 16 to 29 wherein said oil is selected from palm oil, coconut oil, olive oil, canola oil, soya bean oil, corn oil, avocado oil, oil of other fruits and nuts, essential oils from herbs, citrus oil, or tea tree oil.

31. A method according to any one of claims 16 to 29 where the liquid mixture comprises algae-derived oils.

32. A method according to any one of claims 16 to 29 where the liquid mixture comprises animal-derived oils.

33. The method of any one of claims 16 to 32, which is applied in combination with a method according to any one of claims 1 to 8. Cavitus Pty Ltd Patent Attorneys for the Applicant/Nominated Person SPRUSON & FERGUSON