FIELD OF THE INVENTION

The present invention relates to a method of recovering oil from a plant oil mill colloidal suspension having aqueous solution and system thereof. More particularly, the present invention relates a method for the recovery of oil from an aqueous solution containing plant- derived material from the colloidal suspension of a plant oil processing plant, such as colloidal suspension.

BACKGROUND OF THE INVENTION

Plant-derived oil can be produced from seeds which contain oil, and from oleaginous fruits such as palm fruits. The production of fruit oil is most generally practiced by using a wet pressing method. As a side fraction, wet pressing yields a colloidal suspension, consisting of water-soluble components of fruit and a material suspended in water, particularly fibers and oil. Current wet pressing generates plant liquors which is a colloidal suspension then discharge as palm oil mill effluent (POME), contains typically 95 to 96% water, about 1% oil, and has a total dry solid content of 4 to 5%, of which the suspended solid matter makes up 2 to 4%. Main sources of plant liquors include empty fruit bunch pressed liquor, decanter heavy phase, light phase sludge, sterilizer condensate, separator sludge or oil clarifier, and hydrocyclone effluent. The palm oil wet pressing process consumes plenty of water and produces a large quantity of POME. Despite the pollutant contained in POME, POME also contains high concentrations of recoverable protein, carbohydrate, nitrogenous compounds, lipids and minerals that may be converted into useful materials. It is desirable to treat the POME prior to discharge to recover useful materials as well as reducing environmental burden.

Accordingly, there is a particular need for a treatment method, which enables both recovering oil from the colloidal suspension of a fruit pressing plant and concurrently reducing the environmental burden of this colloidal suspension.

Prior art, W02014051415A1 disclosed an oil recovering system having a plurality of equipment, which are connected to form a continuous processing line, comprising a waste oil transfer tank containing an oil- based waste colloidal suspension; a first heater for dissolving solids in the waste colloidal suspension; a screening machine located downstream of the first heater for removing undissolved solids from the heated waste oil to produce a first filtered waste colloidal suspension; a second heater for heating the first filtered waste colloidal suspension; a catalyst feedstock containing a catalyst; a reactor for mixing the catalyst from the catalyst feedstock with the heated first filtered waste colloidal suspension to form an oil phase, a solid phase and a water phase; a centrifuge operable for separating the oil phase from the solid and water phases to produce a purified oil, characterized in that the equipment are mounted on a vehicle for portability. However, this system requires heating and chemicals to be used for treatment and it is limited to batch treatment.

Prior Art, WO2017183955A1 disclosed Solid Removal Oil Recovery System (SRORS) for treatment, mainly oil recovery and suspended solids removal, of palm oil mill and related refinery raw sludge and a treatment process using said SRORS is presented wherein said SRORS comprises at least a holding tank, a plurality of filtration assemblies connected in series, a slurry tank and a decanter system and with said holding tank, said plurality of filtration assemblies, said slurry tank and said decanter system suitably connected for process, treatment and discharge of the treated materials. The raw sludge is discharged and stored in the holding tank with said raw sludge transferred to the plurality of filtration assemblies for treatment, specifically cross flow filtration, with filtrate and slurry the primary end products of said treatment.

While another prior art, WO2018067001 A2 disclosed a Solid Removal Oil Recovery System (SRORS) for treatment of palm oil mill and related refinery raw sludge wherein said SRORS comprises at least a holding tank for receiving and storing palm oil mill and related refinery raw sludge; a plurality of concentration tanks into which raw sludge from said holding tank is discharged in batches; a plurality of filtration modules, connected in parallel, for treatment specifically continuous cross flow filtration of raw sludge/slurry with filtrate and more concentrated slurry the main products of said treatment; said plurality of concentration tanks connectable to said filtration modules and with raw sludge discharged singly from said plurality of concentration tanks to said plurality of filtration modules for treatment and with the resulting more concentrated slurry circulated back to the connected concentration tank; at least a slurry tank to receive and to store the more concentrated slurry from the concentration tanks; a decanter system for solid removal and oil recovery from said slurry from said slurry tank; and said treatment of raw sludge/slurry by said plurality of filtration modules being a substantially continuous process while feed of raw sludge from said holding tank to said plurality of concentration tanks and discharge of more concentrated slurry from said plurality of concentration tanks to the slurry tank are carried out in batches or semi-continuous. The drawbacks of these two prior arts is that the potential membrane clogged in a short duration due to the use of conventional tubular cross-flow membrane used in the SRORS. As conventional crossflow tubular membrane can only generate the high crossflow velocity by pumping high volume of liquid through the membrane, the pumping energy cost is very extremely high. In addition, this limits the velocity of crossflow of the liquid within the system because the maximum achievable crossflow velocity by pumping liquid is 4m/s. Further increase in velocity results in high pressure on the membrane and attribute faster irreversible membrane fouling and clogging.

In view of the above shortcomings, the present invention aims to provide a seamless method of recovering oil from a plant oil mill colloidal suspension having aqueous solution and system thereof. Furthermore, the system of the present invention provides an improvement of the crossflow velocity of the liquid and without having the need of a recirculation pump within the system without compromising the crossflow velocity of the liquid on the membrane and prolonged the use of the membrane. The crossflow velocity of the present invention is generated by the rotation of the disc membrane which is independent of the liquid pumping flow into the system. In addition, such system can be conveniently installed and maintained in a simple technical process, low cost with high efficiency.

SUMMARY OF THE INVENTION

The present invention provides a method of recovering oil from a plant oil mill colloidal suspension having aqueous solution comprising the following steps of providing the plant oil mill colloidal suspension into a vibrating screener for removing coarse fibrous solids and sand to form a screened plant oil mill colloidal suspension containing oil and solids; providing an equalizing tank for storing the screened plant oil mill colloidal suspension containing oil and solids; channeling the screened plant oil mill colloidal suspension containing oil and solids from the equalizing tank into a dynamic cross-flow filtration system to separate into a filtrate and a concentrate; and recovering the oil from the concentrate. The method of the present invention further comprising collecting the filtrate and providing a treatment to the filtrate prior to discharge as effluent.

In addition, the step of recovering the oil from the concentrate further comprising separating the oil by a decanter system and the dynamic cross-flow filtration system further comprising at least two modules of rotating ceramic disc dynamic crossflow filtration unit. The rotating ceramic disc dynamic cross-flow filtration unit having a rotating dynamic disc membrane.

The plant oil mill colloidal suspension of the present invention having aqueous solution is a palm oil mill colloidal suspension. Meanwhile, the concentrate of a palm oil mill colloidal suspension (POME) after separation by the dynamic cross-flow filtration system having the following characteristics a) 2-5% by volume of Oil and Grease; b) 85-90% by volume of Water content; and c) 7-15% by volume of Solids

The filtrate of a palm oil mill colloidal suspension after separation by the dynamic cross-flow filtration system having the following characteristics a) 0.015-0.02 % by volume of Oil and Grease; b) 99-99.5 % by volume of Water content; and c) 0.01 -0.02 % by volume of Solids

The oil phase of a palm oil mill colloidal suspension after separation by the decanter system having the following characteristics a) 25-70% by volume of Oil and Grease; b) 25-55% by volume of Water content; and c) 2-4% by volume of Solids

The oil phase recovered in the method of the present invention is of crude palm oil grade which is a substance suitable for fuel application, such as for example biodiesel or renewable transportation fuel as well as to be refined as cooking oil.

A system for recovering oil from a plant oil mill colloidal suspension having aqueous solution comprising a vibrating screener for removing coarse fibrous solids and sand from the plant oil mill colloidal suspension having aqueous solution to form a screened plant oil mill colloidal suspension containing oil and solids; an equalizing tank for storing the screened plant oil mill colloidal suspension containing oil and solids; a dynamic cross-flow filtration system is provided to separate into a filtrate and a concentrate; and a decanter system for separating the concentrate into oil phase, solid phase and water phase.

In one of the embodiments of the present invention, the dynamic cross-flow filtration system further comprising at least two modules of rotating ceramic disc dynamic crossflow filtration unit.

In another embodiment of the present invention, the rotating ceramic disc dynamic cross-flow filtration unit having a rotating dynamic disc membrane. Meanwhile, the solids are organic solids. The plant oil mill colloidal suspension having aqueous solution is a palm oil mill colloidal suspension and the decanter system is a three-phase decanter.

One of the advantages of the system is that it provides a seamless method of recovering oil from a plant oil mill colloidal suspension having aqueous solution and system thereof. Furthermore, the system of the present invention provides an improvement of the cross-flow velocity of the liquid on the membrane without a need for recirculation pump within the system and maintaining the velocity of the liquid for treatment and prolonged use of the membrane. Furthermore, the system of the present invention allows continuous process of treatment in high volume of colloidal suspension in any temperature of the colloidal suspension. In addition, the recovered oil from the method of the present invention is of high purity and on par with crude palm oil which is suitable for edible or fuel application, such as for example biodiesel or renewable transportation fuel. A particular benefit of the invention is its capability of using simple technical solutions to produce remarkable quantities of palm oil from palm oil colloidal suspension, a low rated side stream of palm oil production.

In another advantages of the system and method of the present invention is that almost all the suspended solids have been removed by the system, the aqueous fraction that goes into the existing wastewater treatment plant such as anaerobic or biogas system having less sediment in the tank or lagoon. Therefore, tremendously lowering the needs for desludging for anaerobic lagoon or tank. In furtherance, the organic contaminant mainly biochemical oxygen demand (BOD) and chemical oxygen demand (COD) also reduced by a significant amount in the aqueous fraction before being discharged to the effluent treatment pond. As the loading of organic contaminant tremendously reduced, the existing effluent treatment system can treat the effluent to a better quality compared to before.

Further advantages of the system in accordance with the invention and its application can be derived from the description and the accompanying drawings. The above-mentioned features and those to be further described below can be utilized in accordance with the invention individually or collectively in arbitrary combination. The embodiments mentioned are not to be considered exhaustive enumerations, rather have exemplary character. The invention is shown in the drawings and explained more closely with reference to embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.

Figure 1 illustrates a schematic diagram of a system for recovering oil from a plant oil mill colloidal suspension having aqueous solution in accordance with the present invention.

Figure 1A illustrates a schematic diagram of a system having two modules for operation of rotating ceramic disc dynamic crossflow filtration unit for recovering oil from a plant oil mill colloidal suspension having aqueous solution in accordance with the present invention.

Figure 2 illustrates a schematic diagram of a batch system for recovering oil from a plant oil mill colloidal suspension having aqueous solution in accordance with the present invention.

Figure 3 illustrates a schematic diagram of a continuous system for recovering oil from a plant oil mill colloidal suspension having aqueous solution in one of the embodiments in accordance with the present invention.

Figure 4 illustrates a schematic diagram of a continuous system for recovering oil from a plant oil mill colloidal suspension having aqueous solution in another embodiment in accordance with the present invention. DETAILED DESCRIPTIONS OF THE INVENTION

The present invention will now be described in detail in connection with specific embodiments with reference to the accompanying drawings. Unless the context requires otherwise, throughout the specification and claims which follow, the word “comprise” and variations thereof, such as, “comprises” and “comprising” are to be construed in an open, inclusive sense that is as “including, but not limited to”. Reference throughout this specification to “one embodiment” or “an embodiment” means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, the appearances of the phrases “in one embodiment” or “in an embodiment” in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. With respect to the use of substantially any plural and/or singular terms herein, those having skill in the art can translate from the plural to the singular and/or from the singular to the plural as is appropriate to the context and/or application. The various singular/plural permutations may be expressly set forth herein for sake of clarity. It will be further understood by those within the art that virtually any disjunctive word and/or phrase presenting two or more alternative terms, whether in the description, claims, or drawings, should be understood to contemplate the possibilities of including one of the terms, either of the terms, or both terms. For example, the phrase "A or B" will be understood to include the possibilities of "A" or "B" or "A and B."

Figure 1 illustrates a schematic diagram of a system (100) for recovering oil from a plant oil mill colloidal suspension having aqueous solution in accordance with the present invention. A system (100) for recovering oil from a plant oil mill colloidal suspension of the present invention having aqueous solution comprising a vibrating screener (102) for removing coarse fibrous solids and sand from the plant oil mill colloidal suspension having aqueous solution to form a screened plant oil mill colloidal suspension containing oil and solids; an equalizing tank (104) for storing the screened plant oil mill colloidal suspension containing oil, water and solids; a dynamic cross-flow filtration (DCFF) system (106) is provided to separate into a filtrate and a concentrate; and a decanter system (108) for separating the concentrate into oil phase, solid phase and water phase. The term “sand” refers in this context particularly to a material, having its grain size (particle size) varying within the range of 0.5 to 4 mm. The vibrating screener is preferably a stainless-steel wire mesh screen with holes of between 0.5 to 4mm. The vibratory mechanism is used to remove the trapped solids from the wire mesh to ensure continuous operation.

The dynamic cross-flow filtration system (106) of the present invention having at least two modules of rotating ceramic disc dynamic crossflow filtration unit as illustrated in Figure 1A. Each rotating ceramic disc dynamic cross-flow filtration unit having a rotating dynamic disc membrane with a low pumping energy having one electric motor per a rotating ceramic disc dynamic cross-flow filtration unit for moving the rotating dynamic disc membrane. The solids of the screened plant oil mill colloidal suspension containing oil and solids are organic solids. The plant oil mill colloidal suspension having aqueous solution of the present invention is a palm oil mill colloidal suspension and palm oil empty fruit bunch pressed liquor. However, the system and method of the present invention for recovery oil can be applied to other plant oil mill colloidal suspension having aqueous solution such as soya bean oil mill colloidal suspension, olive oil mill colloidal suspension or any colloidal suspension derived from plant origin such as peanut oil, sunflower oil and any plant oil that uses water in extraction of plant oil. In one of the embodiments of the present invention the decanter system is a three-phase decanter. In an alternative embodiment of the present invention, the decanter system is a two- phase decanter.

In operation, a method of recovering oil from a plant oil mill colloidal suspension having aqueous solution comprising the following steps of providing the plant oil mill colloidal suspension into a vibrating screener for removing coarse fibrous solids and sand to form a screened plant oil mill colloidal suspension containing oil and solids. Next, an equalizing tank is provided for storing the screened plant oil mill colloidal suspension containing oil and solids to achieve a continuing process for recovery of oil. Then, the screened plant oil mill colloidal suspension containing oil and solids is channeled from the equalizing tank into a dynamic cross-flow filtration system to separate into a filtrate and a concentrate. Finally, recovering the oil from the concentrate. For increase the purity of the content of recovered oil, a decanter system is provided for further separation into three phases that is water phase, oil phase, and solid phase. The recovered oil in the oil phase is used as a substance suitable is on par with the quality of crude palm oil or fuel application, such as for example biodiesel or renewable transportation fuel. Meanwhile for the collected filtrate, a further treatment is provided such as filtration, sedimentation pond prior to discharge as effluent. Example 1

Figure 2 illustrates a schematic diagram of a batch system for recovering oil from a plant oil mill colloidal suspension having aqueous solution in accordance with the present invention. In operation, an equalizing Tank 1 was provided with was filled with raw liquor from palm oil mill colloidal suspension. When the equalizing Tank 1 was full, the DCFF began operation. Then operation began, as the filtrate was produced with a volume of concentrate was recirculated to equalizing Tank 1 . As the filtrate was discharged, the liquor within equalizing Tank 1 having more concentrated and the volume of liquor reached to a lower level. Meanwhile, as the level of the liquor in equalizing Tank 1 reached to one third (1/3) to a one fifth (1/5) of the original volume when the Tank 1 was full, the predetermined concentration was reached. When equalizing Tank 1 in a Filtration cycle, equalizing Tank 2 was in Fill Cycle where raw liquor going through the vibrating screener entered Equalizing Tank 2. Once equalizing Tank 1 Filtration cycle ended, the concentrate in Equalizing Tank 1 fed into the 3-phase decanter for oil recovery. As equalizing Tank 1 undergoing a decanter cycle, equalizing Tank 2 undergone a Filtration cycle followed by a decanter cycle. Such cycles were repeated in an alternating manner between equalizing Tank 1 and equalizing Tank 2. The concentration of both oil and solids in both equalizing tanks increased progressively and the level of liquid in the tank dropped gradually. Such cycles were also repeated for continuous operation. Depending on the characteristic of the colloidal suspension, the flow rate of the palm oil mill colloidal suspension can be adjusted according to different predetermined concentration for effective high recovery of oil.

Table 1 illustrated the content of BOD, COD, oil and grease and suspended solids before and after treatment of the system and method of the present invention. One can observed that the value of these parameters decreased significantly.

Table 1 - Palm Oil Mill Colloidal suspension and filtrate after a dynamic cross-flow filtration (DCFF) system

Table 2 shows oil and grease and solid analysis and mass balance of of the system and method of the present invention after a dynamic cross-flow filtration (DCFF) system. It can be observed that the concentrate having oil for recovery is within 2-5% and higher than raw POME and filtrate. Table 2 - Oil and grease and solid analysis and mass balance of of the system and method of the present invention after a dynamic cross-flow filtration (DCFF) system.

Table 3 - Oil and Grease after the Concentrate from a dynamic cross-flow filtration (DCFF) system further separated by a 3-phase Decanter

The oil phase after separated by 3-phase decanter increased significantly to 25-35% which can be used for a substance suitable for fuel application, such as for example biodiesel or renewable transportation fuel.

Example 2

Figure 3 illustrates a schematic diagram of a continuous system for recovering oil from a plant oil mill colloidal suspension having aqueous solution in one of the embodiments in accordance with the present invention. One can observed that the concentration of flowrate of the concentrate with slower velocity at the end of the filtration due to viscosity of raw liquor with high content of oil after filtration by a series of modules of rotating ceramic disc dynamic crossflow filtration unit in a dynamic cross-flow filtration (DCFF) system.

Example 3

Figure 4 illustrates a schematic diagram of a continuous system for recovering oil from a plant oil mill colloidal suspension having aqueous solution also known as raw liquor in another embodiment in accordance with the present invention. In operation, one filtration of a dynamic cross-flow filtration (DCFF) system consisted of two trains known as train A and train B in this case of DCFF to enable relay and maintenance to be provided. The term “train” used in this patent specification refers to a series of modules of rotating ceramic disc dynamic crossflow filtration unit in a dynamic cross-flow filtration (DCFF) system. When Train A stopped for operation due to maintenance while Train B continued in operation or vice versa. Each train of DCFF consisted of three rotating ceramic disc dynamic crossflow filtration unit modules, as shown in Figure 4. The raw liquor was fed into DCFF (A1 ) and the filtrate (FA1 ) was generated and the concentrate (CA1 ) from DCFF (A1 ) flowed to DCFF (A2) where the filtrate (FA2) was generated and concentrate (CA2) from DCFF (A2) then channeled to DCFF (A3) where the Filtrate (FA3) was generated and concentrate (CA3) was the final concentrate which then flowed to Concentrate Tank (402). As raw liquor being filtered in DCFF (A1 ) and the filtrate (FA1 ) was discharged, the original feed volume reduced and thereby concentrated the liquid in DCFF (A1 ). The concentrated liquor from DCFF (A1 ) which is (CA1 ) had a lesser volume as compared to the original feed liquor. Meanwhile, concentrate CA1 was fed into DCFF (A2), while the filtrate (FA2) was generated thereby further reduced the volume of liquid in DCFF (A2). Therefore, the liquor provided after DCFF (A2) became more concentrated (CA2). Then concentrate CA2 flowed into DCFF (A3) and the filtrate (FA3) was generated, thereby further reduced the volume of liquor in DCFF (A3). Therefore, the final concentrate from DCFF (A3) which was CA3 had a highest concentration and lowest volume channeled into concentrate tank (402). Finally, depending on the applications, the concentrated liquor fed to a 3-phase decanter or 2-phase decanter for oil recovery. The recovered oil can be transferred to a recovered oil tank for storage.

Another benefit gained by a method of the present invention is that its individual unit operations produce fractions which are suitable for various applications. The recovered palm oil is applicable to any inherent usage applications of palm oil or preferably for the production of renewable transportation fuel. The biological solids particle mass, i.e. the carbohydrate-rich and low oil particles contained in POME, is applicable to renewed use as such or after processing, such as for use as a soil improver or for combustion as well as animal feed meal. It is possible that water be further processed and purified by using prior known POME treatment methods and be used as a recycling stream in palm oil production or as a stream used for irrigation, as a soil improver or a fertilizer supplement, or the purified water can be released into the environment. The present invention provides a comprehensive solution for upgrading the production process in terms of its environmental friendliness and economic sense.

The method according to the invention is simple, modest in terms of equipment required therefor, and thereby attractive in terms of its investment costs. Implementation of the method does not require any special skills, either. The method is modest in terms of its energy demand, it is low in practice as regards its emissions, the commodities needed therefor are recyclable in the process, and the side streams produced thereby, such as oil, other biomass, and water, can be used for surplus value producing applications.

Implementation of the method and system according to embodiments of the invention involves performing or completing selected tasks or steps manually, automatically, or a combination thereof. Moreover, according to actual instrumentation and equipment of exemplary embodiments of methods, apparatus and systems of the invention, several selected steps could be implemented by hardware or by software on any operating system of any firmware or a combination thereof, for example, as hardware, selected steps of the invention could be implemented as a chip or a circuit. As software, selected steps of the invention could be implemented as a plurality of software instructions being executed by a computer using any suitable operating system. In any case, selected steps of the method and system of the invention could be described as being performed by a data processor, such as a computing platform for executing a plurality of instructions.

The foregoing detailed description and examples are merely illustrative of the preferred embodiments. They are by no means meant to be the exclusive description of the inventive concept hereby disclosed. It will be recognized by one of ordinary skill in the art that certain aspects of the practice of the invention are readily susceptible to modification or practice by alternative, known means.