WO2015190908A1 - Method for producing biofertilizers in palm oil mills using green technology - Google Patents
Method for producing biofertilizers in palm oil mills using green technology Download PDFInfo
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- WO2015190908A1 WO2015190908A1 PCT/MY2014/000258 MY2014000258W WO2015190908A1 WO 2015190908 A1 WO2015190908 A1 WO 2015190908A1 MY 2014000258 W MY2014000258 W MY 2014000258W WO 2015190908 A1 WO2015190908 A1 WO 2015190908A1
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- Prior art keywords
- biofertilizer
- mixed
- produce
- effluent
- evaporation
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Classifications
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- C—CHEMISTRY; METALLURGY
- C11—ANIMAL OR VEGETABLE OILS, FATS, FATTY SUBSTANCES OR WAXES; FATTY ACIDS THEREFROM; DETERGENTS; CANDLES
- C11B—PRODUCING, e.g. BY PRESSING RAW MATERIALS OR BY EXTRACTION FROM WASTE MATERIALS, REFINING OR PRESERVING FATS, FATTY SUBSTANCES, e.g. LANOLIN, FATTY OILS OR WAXES; ESSENTIAL OILS; PERFUMES
- C11B13/00—Recovery of fats, fatty oils or fatty acids from waste materials
-
- C—CHEMISTRY; METALLURGY
- C05—FERTILISERS; MANUFACTURE THEREOF
- C05F—ORGANIC FERTILISERS NOT COVERED BY SUBCLASSES C05B, C05C, e.g. FERTILISERS FROM WASTE OR REFUSE
- C05F17/00—Preparation of fertilisers characterised by biological or biochemical treatment steps, e.g. composting or fermentation
- C05F17/40—Treatment of liquids or slurries
-
- C—CHEMISTRY; METALLURGY
- C05—FERTILISERS; MANUFACTURE THEREOF
- C05F—ORGANIC FERTILISERS NOT COVERED BY SUBCLASSES C05B, C05C, e.g. FERTILISERS FROM WASTE OR REFUSE
- C05F17/00—Preparation of fertilisers characterised by biological or biochemical treatment steps, e.g. composting or fermentation
- C05F17/50—Treatments combining two or more different biological or biochemical treatments, e.g. anaerobic and aerobic treatment or vermicomposting and aerobic treatment
-
- C—CHEMISTRY; METALLURGY
- C05—FERTILISERS; MANUFACTURE THEREOF
- C05F—ORGANIC FERTILISERS NOT COVERED BY SUBCLASSES C05B, C05C, e.g. FERTILISERS FROM WASTE OR REFUSE
- C05F5/00—Fertilisers from distillery wastes, molasses, vinasses, sugar plant or similar wastes or residues, e.g. from waste originating from industrial processing of raw material of agricultural origin or derived products thereof
- C05F5/002—Solid waste from mechanical processing of material, e.g. seed coats, olive pits, almond shells, fruit residue, rice hulls
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
- Y02A40/00—Adaptation technologies in agriculture, forestry, livestock or agroalimentary production
- Y02A40/10—Adaptation technologies in agriculture, forestry, livestock or agroalimentary production in agriculture
- Y02A40/20—Fertilizers of biological origin, e.g. guano or fertilizers made from animal corpses
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P20/00—Technologies relating to chemical industry
- Y02P20/141—Feedstock
- Y02P20/145—Feedstock the feedstock being materials of biological origin
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
- Y02W30/00—Technologies for solid waste management
- Y02W30/40—Bio-organic fraction processing; Production of fertilisers from the organic fraction of waste or refuse
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
- Y02W30/00—Technologies for solid waste management
- Y02W30/50—Reuse, recycling or recovery technologies
- Y02W30/74—Recovery of fats, fatty oils, fatty acids or other fatty substances, e.g. lanolin or waxes
Definitions
- the present invention relates in general to a method for treating palm oil mill effluent (POME) using green technology, and in particular to a method for utilizing POME for producing biofertilizers.
- POME palm oil mill effluent
- POME palm oil mill effluent
- BOD biological oxygen demand
- DOE Department of Environment
- POME is a colloidal slurry containing water, oil, cellulosic fruit debris, gums, sand and water-soluble dissolved components originating from palm fruits. It is non-toxic as no chemicals are added during the oil extraction process. It is made up of about 94 percent water, 1 percent oil and 5 percent solids. Studies have indicated that POME is a good source of plant nutrients such as nitrogen (N), phosphorus (P), potassium ( ) and magnesium (Mg). Untreated POME is not generally used as a fertilizer due to the large quantity available and its high organic matter and gum contents. Land application of partially treated POME is only allowed by the Department of Environment if it does not adversely affect the environment, in particular groundwater quality. The large quantity of POME also implies that transportation costs to utilize it as a fertilizer can be high, especially for mills that are not located adjacent to plantations.
- Drying of POME can generally be used to bring down the transportation costs, but the high moisture content of POME, the large quantity to be dried, the high sand content and the stickiness of the product being dried has meant that drying of POME is generally an expensive, energy-intensive and difficult operation that cannot normally be carried out using only the solid wastes generated by the palm oil milling process as energy sources.
- a problem faced with drying POME is that it undergoes an intermediate viscous or sticky phase. This causes the product being dried to stick to the surfaces of the drier and to agglomerate and form an impervious crust that impacts the overall heat transfer rate. This decreases the efficiency of the drier, extends the drying time, effects the homogeneity of the dried product and, may possibly, lead to the breakdown of the drier.
- Evaporation has been used as a more energy-efficient method than drying for concentrating effluent in various industries. Nevertheless, the most widely used evaporator ⁇ i.e. the falling film evaporator) is not suitable for removing water directly from untreated POME.
- the large quantity of suspended solids and gums in untreated POME will lead to the formation of a hard scale on the heating surfaces of the falling film evaporator.
- the product leaving the falling film evaporator will have high moisture content since it will not be possible to concentrate untreated POME beyond approximately 20 percent solids due to the abovementioned problems. It will have little or no economic value, either as a food product or as a fertilizer, due to the high moisture content and the very high sand and suspended solids content. It cannot be easily dried using a rotary drier due to its high moisture content and the drying problems highlighted above.
- the product will also be very abrasive due to the high sand content.
- the invention disclosed herein addresses the problems currently faced as described hereinbefore, by way of utilizing palm oil mill effluent (POME) as a biofertilizer. Evaporation is used to significantly reduce the quantity of partially treated effluent discharged from palm oil mills to make it suitable for utilization as a biofertilizer.
- POME palm oil mill effluent
- the partially treated effluent will have significandy lower suspended solids and gum contents. It is an excellent fertilizer as it contains considerable amounts of nitrogen, phosphorus and potassium (NPK), which are the key components of a good fertilizer.
- NPK nitrogen, phosphorus and potassium
- the majority of plant nutrients present in POME will transfer to the partially treated effluent, with the exception that some nitrogen may be lost as ammonia and sulphur as hydrogen sulphide.
- the digestion process renders the nitrogen more available for crop uptake.
- partially treated effluent Due to the large amount of the partially treated effluent, it may require further treatment before it can be utilized as a fertilizer since land application of partially treated effluent is generally not permitted in environmentally sensitive areas if the potential exists for it to contaminate local groundwater sources.
- the large amount of partially treated effluent also implies that transportation costs to utilize it as a fertilizer can be high, especially for mills not located adjacent to oil palm plantations.
- the partially treated effluent is subjected to further treatment.
- Most of the suspended solids in the partially treated effluent is separated using a mechanical separation means.
- the separation is advantageously achieved using a two-phase decanting centrifuge, a belt press, a filter press or a multi-disk screw press.
- the partially treated effluent may be chemically dosed to assist in the flocculation of solids to improve the separation of solids by the mechanical separation means.
- the cake discharged from the mechanical separation means can be used as a biofertilizer without undergoing any further treatment.
- the clarified liquor discharged from the mechanical separation means is a good source of dissolved plant nutrients.
- the clarified liquor After passing through the mechanical separation means, the clarified liquor contains considerably less suspended solids. Its value as a fertilizer can be significantly enhanced by reducing its moisture content in an energy-efficient manner using an evaporation means to produce a concentrated liquid bio fertilizer.
- the clarified liquor may be chemically dosed to precipitate volatile organic and inorganic components contained therein to minimize the carry-over of such components to the condensate discharged from the evaporation means.
- Biological treatment of POME addresses many of the problems faced with evaporation and drying of POME arising from its high suspended solids and gum contents. The reduction in suspended solids content using the mechanical separation means prior to evaporation also contributes to minimizing fouling of the evaporation means.
- the moisture content of the concentrated liquid biofertilizer may be further reduced by using a drying means to produce a solid biofertilizer.
- the concentrated liquid biofertilizer is mixed with the cake discharged from the mechanical separation means to produce a mixed biofertilizer.
- the mixed biofertilizer may subsequently be mixed with one or more bulking materials and used as mulch without further drying.
- the bulking materials may be empty fruit bunches, decanter cake, bunch ash, boiler ash, palm fruit fibre, palm kernel expeller cake or saw dust, or combination thereof.
- the mixed biofertilizer may also be dried using a drying means that is adopted for drying materials having high solids content to produce a solid mixed biofertilizer.
- a multiple-effect evaporator system makes possible the removal of moisture from the liquid discharged from the dewatering means using a fraction of the energy required by a drier to remove an equal amount of moisture from POME, especially if heated air is used to supply the energy for drying.
- evaporation is advantageously carried out using evaporators that are specially designed to concentrate highly viscous and heat sensitive products that tend to stick or foul the heat transfer surface.
- the most suitable evaporators for our application are forced circulation evaporators and scraped surface evaporators or evaporators using a combination of these two evaporation methods.
- the use of the falling film evaporation method should be limited to the first one or two stages only of a multiple-effect evaporator system when the viscosity of the product being evaporated is still sufficiently low. Drying of the concentrated liquid biofertilizer is ideally achieved by using a spray dryer. Spray drying is a one-step processing operation for toning a liquid feed into a dried particulate form by spraying the feed into a hot drying gas medium. Because spray drying is a relatively energy-intensive method for removing water, an evaporator is advantageously used for the removal of the bulk of the water in POME before drying into a dried particulate form using a spray dryer.
- An evaporator can be used to remove the bulk of the water in POME and to reduce the moisture content of the evaporated product to less than 70%. At this moisture content, the product becomes too viscous to pump through the evaporator.
- Spray dryers can handle viscous products very well. For this reason, a spray dryer is advantageously used to concentrate the concentrated liquid biofertilizer further to a dried product having a moisture content of about 0%.
- Drying of the mixed biofertilizer produced by mixing the cake discharged from the mechanical separation means with the concentrated liquid biofertilizer from the evaporation means, may be achieved using a drying means that is adopted for drying materials having high solids content.
- the drying of the mixed biofertilizer is advantageously carried out using a rotary dryer or a paddle dryer.
- the condensate may be treated biologically, chemically (for example using biocides), physically (for example using microfilters, ultrafilters, nanonlters, reverse osmosis or granular activated carbon filters), or a combination thereof, and recycled for use in the palm oil mill.
- the condensate that is not recycled back to the palm oil mill can be treated biologically using a small effluent treatment plant, such as a sequencing batch reactor (SBR) or membrane bioreactor (MBR), before it is discharged.
- a small effluent treatment plant such as a sequencing batch reactor (SBR) or membrane bioreactor (MBR)
- Figure 1 illustrates schematically one preferred embodiment of the present invention, wherein the liquor from anaerobic treatment of POME is utilized to produce the concentrated liquid biofertilizer that may subsequently be dried.
- Figure 2 illustrates schematically another preferred embodiment of the present invention, wherein the liquor from anaerobic treatment of POME is utilized to produce the concentrated liquid biofertilizer and the cake discharged from the mechanical separation step is subsequently mixed with the concentrated liquid biofertilizer to produce a mixed biofertilizer.
- Figure 3 illustrates schematically yet another preferred embodiment of the present invention, wherein the liquor from aerobic treatment of POME is utilized to produce the concentrated liquid biofertilizer that may subsequently be dried.
- Figure 4 illustrates schematically still yet another preferred embodiment of the present invention, wherein the liquor from aerobic treatment of POME is utilized to produce the concentrated liquid biofertilizer and the cake discharged from the separation step is subsequently mixed with the concentrated liquid biofertilizer to produce a mixed biofertilizer.
- FIG 1 illustrates schematically one preferred embodiment of the present invention, wherein the liquor from anaerobic treatment of palm oil mill effluent (POME) is utilized to produce the concentrated liquid biofertilizer that is subsequendy dried.
- the POME 200 is initially treated using an anaerobic digestion means 201 to break down organic matter (generally quantified as biological oxygen demand or BOD) using microorganisms.
- the liquor from anaerobic treatment of POME 203 is then treated using mechanical separation means 204 to remove suspended solids prior to evaporation.
- the use of the mechanical separation means 204 generates two phases.
- One phase is easily disposable cake 205 having moisture content less than 80% that can be utilized as a biofertilizer without any further treatment.
- clarified liquor 206 containing mainly water, soluble solids and fine fibrous solids.
- Clarified liquor 206 is processed using evaporation means 207 to remove the bulk of the water and other volatile components that it contains in an energy-efficient manner to form concentrated liquid biofertilizer 209 and condensate 208 containing the volatile components.
- Concentrated liquid biofertilizer 209 may then be dried using drying means 210 to produce solid biofertilizer 211.
- Condensate 208 may be treated biologically, chemically, physically, or a combination thereof, and recycled for use in the palm oil mill, or otherwise it is treated biologically using a small effluent treatment plant before it is discharged.
- FIG 2 illustrates schematically another preferred embodiment of the present invention, wherein the liquor from anaerobic treatment of POME is utilized to produce the concentrated liquid biofertilizer and the cake discharged from the mechanical separation step is subsequendy mixed with the concentrated liquid biofertilizer to produce a mixed biofertilizer.
- the POME 300 discharged from palm oil mills is initially treated using a similar approach to the mode illustrated by Figure 1.
- concentrated liquid biofertilizer 309 is mixed with cake 305 to form mixed biofertilizer 311 instead of being dried.
- Mixed biofertilizer 311 may be further processed using drying means 312 to generate solid mixed biofertilizer 313.
- the drying method used will be different from the drying method used for drying the liquid biofertilizer due to the higher solids content.
- mixed biofertilizer 311 may be utilized without further drying. It may subsequendy be mixed with one or more bulking materials and utilized as mulch.
- FIG 3 illustrates schematically another preferred embodiment of the present invention, wherein the liquor from aerobic treatment of POME is utilized to produce the concentrated liquid biofertilizer that is subsequendy dried.
- the POME 400 discharged from palm oil mills is first treated using anaerobic digestion means 401 and aerobic digestion means 404 operating in series to break down organic matter (generally quantified as biological oxygen demand or BOD) using microorganisms.
- the liquor from the aerobic digestion means will have lower total solids and suspended solids content then the digestate from the anerobic digestion means. Its use as feed to the evaporation means will lead to less fouling problems.
- the liquor from aerobic treatment of POME 405 is treated using a similar approach to the mode illustrated by Figure 1 to produce concentrated liquid biofertilizer 411, which may then be dried using drying means 412 to produce solid biofertilizer 413.
- FIG 4 illustrates schematically another preferred embodiment of the present invention, wherein the liquor from aerobic treatment of POME is utilized to produce the concentrated liquid biofertilizer and the cake discharged from the mechanical separation step is subsequently mixed with the concentrated liquid biofertilizer to produce a mixed biofertilizer.
- the POME 500 is first treated using anaerobic digestion means 501 and aerobic digestion means 504 operating in series using a similar approach to the mode illustrated by Figure 3.
- the aerobic liquor 505 from aerobic treatment of POME is then further treated using a similar approach to the mode illustrated by Figure 2 to generate mixed biofertilizer 513.
- Mixed biofertilizer 511 may be further processed using drying means 514 to generate solid mixed biofertilizer 515.
- Mixed biofertilizer 511 may subsequendy be mixed with one or more bulking materials and utilized as mulch.
- evaporation may be carried out by using a falling film evaporator, a forced circulation evaporator, a dynamic scraped surface evaporator or an evaporator using a combination of these evaporation methods.
- the use of the falling film evaporation method should be limited to the first one or two stages only of a multiple-effect evaporator system when the viscosity of the product being evaporated is still sufficiently low.
- the use of scraped surface evaporation or forced circulation evaporation methods will minimize fouling of the evaporator as the concentration of solids increases.
- the scraped surface evaporation method is advantageously used as the final evaporation stage of a multiple-effect evaporation system to achieve very high concentration of solids.
- the use of a mechanical separation means prior to evaporation to remove a significant portion of the suspended solids implies that the viscosity of the feed to the evaporator will be quite low compared to the viscosity of raw POME in a conventional mill.
- the concentrated liquid biofertilizer discharged from the evaporator may be concentrated further by drying to make it easier to handle and to rninirnize storage and transportation costs. Drying is ideally carried out using a spray dryer. Because spray drying is a relatively energy-intensive method for removing water, the evaporation means is used for removing the bulk of the water in POME to generate a product having moisture content less than 70%. At this moisture content, the viscosity of the product becomes too high for pumping through the evaporator. The spray dryer is therefore advantageously used to concentrate the concentrated liquid biofertilizer further to a dried product having a moisture content of about 10%.
- the mixed biofertilizer may be dried by using a drying means adopted for drying materials having high solids content.
- the drying of the mixed biofertilizer is advantageously carried out using a rotary dryer or a paddle dryer.
- the mixed biofertilizer may subsequendy be mixed with one or more bulking materials, such as empty fruit bunches, decanter cake, bunch ash, boiler ash, palm fruit fibre, palm kernel expeller cake or saw dust, and utilized as mulch without further drying.
- the present invention finds ready industrial applicability in the palm oil industry as it is a method for converting the effluent discharged from palm oil mills from a product having very litde economic value and requiring substantial investment for its treatment to comply with regulations on discharge standards to a product that can be used as a biofertilizer.
- the invention provides a method for addressing the problems faced with the utilization of the effluent discharged from palm oil mills as a biofertilizer to achieve zero discharge of liquid effluent. In essence it is a modern green technology approach to oil palm milling as it addresses the problem of the high volume of effluent discharged from palm oil mills by utilizing the effluent to generate a useful by-product of economic value.
Abstract
A method is disclosed for utilizing the palm oil mill effluent (200, 300, 400, 500) as a biofertilizer by breaking down organic matter in the effluent (200, 300, 400, 500) biologically using either anaerobic digestion means only, or a combination of anaerobic and aerobic digestion means operating in series, to produce a partially treated effluent and further treating it using a mechanical separation means (204, 304, 406, 506) and an evaporation means (207, 307, 409, 509) to produce a concentrated liquid biofertilizer (209, 309, 411, 511). The concentrated liquid biofertilizer (209, 309, 411, 511) is either directly dried using a spray dryer, or is mixed with the cake (305, 507) discharged from the mechanical separation means (204, 304, 406, 506), to produce a mixed biofertilizer (311, 513), and dried using a dryer that is adopted for drying solids having higher solids content. Alternatively, the mixed biofertilizer (311, 513) is mixed with one or more bulking materials and used as mulch without further drying.
Description
METHOD FOR PRODUCING BIOFERTILIZERS IN PALM OIL MILLS USING GREEN TECHNOLOGY
TECHNICAL FIELD
The present invention relates in general to a method for treating palm oil mill effluent (POME) using green technology, and in particular to a method for utilizing POME for producing biofertilizers.
BACKGROUND ART
The palm oil milling process generates 0.6 to 0.7 tons of palm oil mill effluent (POME) per ton of FFB processed. POME is characterized by a high biological oxygen demand (BOD) and has to be treated to discharge standards stipulated by the Department of Environment (DOE). It is widely acknowledged that a more effective method of treating POME than the widely used anaerobic/aerobic ponding system is needed to comply with the more stringent discharge standards in environmentally sensitive areas. In today's environmental and economic climate, a heightened awareness exists regarding the sustainability of our industrial processes. Companies are now required to focus on best practices to reduce, re-use and re-cycle natural resources as a regular part of doing business.
POME is a colloidal slurry containing water, oil, cellulosic fruit debris, gums, sand and water-soluble dissolved components originating from palm fruits. It is non-toxic as no chemicals are added during the oil extraction process. It is made up of about 94 percent water, 1 percent oil and 5 percent solids. Studies have indicated that POME is a good source of plant nutrients such as nitrogen (N), phosphorus (P), potassium ( ) and magnesium (Mg). Untreated POME is not generally used as a fertilizer due to the large quantity available and its high organic matter and gum contents. Land application of partially treated POME is only allowed by the Department of Environment if it does not
adversely affect the environment, in particular groundwater quality. The large quantity of POME also implies that transportation costs to utilize it as a fertilizer can be high, especially for mills that are not located adjacent to plantations.
Drying of POME can generally be used to bring down the transportation costs, but the high moisture content of POME, the large quantity to be dried, the high sand content and the stickiness of the product being dried has meant that drying of POME is generally an expensive, energy-intensive and difficult operation that cannot normally be carried out using only the solid wastes generated by the palm oil milling process as energy sources. A problem faced with drying POME is that it undergoes an intermediate viscous or sticky phase. This causes the product being dried to stick to the surfaces of the drier and to agglomerate and form an impervious crust that impacts the overall heat transfer rate. This decreases the efficiency of the drier, extends the drying time, effects the homogeneity of the dried product and, may possibly, lead to the breakdown of the drier.
Evaporation has been used as a more energy-efficient method than drying for concentrating effluent in various industries. Nevertheless, the most widely used evaporator {i.e. the falling film evaporator) is not suitable for removing water directly from untreated POME. The large quantity of suspended solids and gums in untreated POME will lead to the formation of a hard scale on the heating surfaces of the falling film evaporator. The product leaving the falling film evaporator will have high moisture content since it will not be possible to concentrate untreated POME beyond approximately 20 percent solids due to the abovementioned problems. It will have little or no economic value, either as a food product or as a fertilizer, due to the high moisture content and the very high sand and suspended solids content. It cannot be easily dried using a rotary drier due to its high moisture content and the drying problems highlighted above. The product will also be very abrasive due to the high sand content.
There is therefore a need in the industry for a method for treating POME that is much less polluting and which generates a by-product of economic value.
DISCLOSURE OF THE INVENTION
The invention disclosed herein addresses the problems currently faced as described hereinbefore, by way of utilizing palm oil mill effluent (POME) as a biofertilizer. Evaporation is used to significantly reduce the quantity of partially treated effluent discharged from palm oil mills to make it suitable for utilization as a biofertilizer.
It is an objective of the present invention to provide a simple, environmentally friendly and cost-effective method for treating (POME).
It is a further objective of the present invention to provide a simple, environmentally friendly and cost-effective method that is suitable for adoption by commercial palm oil mills to convert POME from a product having very little economic value and requiring substantial investment for its treatment to comply with regulations on discharge standards to a product that can be used as a biofertilizer.
It is a further objective of the present invention to provide a simple, environmentally friendly and cost-effective method for treating the discharge from palm oil mills in a manner that obviates the need for treating the discharge biologically using tertiary treatment systems to comply with the more stringent regulations in environmentally sensitive areas.
The above objectives are achieved in the present invention, which is a green technology approach to palm oil milling, by providing a method for producing a concentrated liquid biofertilizer utilizing POME comprising the steps of:
(a) partially digesting palm oil mill effluent from palm oil milling process to produce a partially treated effluent;
(b) separating solids in the partially treated effluent using mechanical separation means to produce a cake and a clarified liquor;
(c) evaporating the clarified liquor using evaporation means to an extent sufficient to produce the concentrated liquid biofertilizer and a condensate containing evaporated components as by-product.
Breaking down organic matter in the POME biologically using either anaerobic digestion means only, or a combination of anaerobic and aerobic digestion means operating in series, to produce the partially treated effluent significandy enhances the value of the POME for use as biofertilizer. The partially treated effluent will have significandy lower suspended solids and gum contents. It is an excellent fertilizer as it contains considerable amounts of nitrogen, phosphorus and potassium (NPK), which are the key components of a good fertilizer. The majority of plant nutrients present in POME will transfer to the partially treated effluent, with the exception that some nitrogen may be lost as ammonia and sulphur as hydrogen sulphide. The digestion process renders the nitrogen more available for crop uptake. Due to the large amount of the partially treated effluent, it may require further treatment before it can be utilized as a fertilizer since land application of partially treated effluent is generally not permitted in environmentally sensitive areas if the potential exists for it to contaminate local groundwater sources. The large amount of partially treated effluent also implies that transportation costs to utilize it as a fertilizer can be high, especially for mills not located adjacent to oil palm plantations.
To make the partially treated effluent more suitable for use as a biofertilizer, it is subjected to further treatment. Most of the suspended solids in the partially treated effluent is separated using a mechanical separation means. The separation is advantageously achieved using a two-phase decanting centrifuge, a belt press, a filter press or a multi-disk screw press. The partially treated effluent may be chemically dosed to assist in the flocculation of solids to improve the separation of solids by the mechanical separation means. The cake discharged from the mechanical separation means can be used as a biofertilizer without undergoing any further treatment. The clarified liquor discharged from the mechanical separation means is a good source of dissolved plant nutrients. After passing through the mechanical separation means, the clarified liquor contains considerably less suspended solids. Its value as a fertilizer can be significantly enhanced by reducing its moisture content in an energy-efficient manner using an
evaporation means to produce a concentrated liquid bio fertilizer. The clarified liquor may be chemically dosed to precipitate volatile organic and inorganic components contained therein to minimize the carry-over of such components to the condensate discharged from the evaporation means. Biological treatment of POME addresses many of the problems faced with evaporation and drying of POME arising from its high suspended solids and gum contents. The reduction in suspended solids content using the mechanical separation means prior to evaporation also contributes to minimizing fouling of the evaporation means.
The moisture content of the concentrated liquid biofertilizer may be further reduced by using a drying means to produce a solid biofertilizer. Alternatively, the concentrated liquid biofertilizer is mixed with the cake discharged from the mechanical separation means to produce a mixed biofertilizer. The mixed biofertilizer may subsequently be mixed with one or more bulking materials and used as mulch without further drying. The bulking materials may be empty fruit bunches, decanter cake, bunch ash, boiler ash, palm fruit fibre, palm kernel expeller cake or saw dust, or combination thereof. The mixed biofertilizer may also be dried using a drying means that is adopted for drying materials having high solids content to produce a solid mixed biofertilizer.
The use of a multiple-effect evaporator system makes possible the removal of moisture from the liquid discharged from the dewatering means using a fraction of the energy required by a drier to remove an equal amount of moisture from POME, especially if heated air is used to supply the energy for drying. To minimize fouling, evaporation is advantageously carried out using evaporators that are specially designed to concentrate highly viscous and heat sensitive products that tend to stick or foul the heat transfer surface. The most suitable evaporators for our application are forced circulation evaporators and scraped surface evaporators or evaporators using a combination of these two evaporation methods. The use of the falling film evaporation method should be limited to the first one or two stages only of a multiple-effect evaporator system when the viscosity of the product being evaporated is still sufficiently low.
Drying of the concentrated liquid biofertilizer is ideally achieved by using a spray dryer. Spray drying is a one-step processing operation for toning a liquid feed into a dried particulate form by spraying the feed into a hot drying gas medium. Because spray drying is a relatively energy-intensive method for removing water, an evaporator is advantageously used for the removal of the bulk of the water in POME before drying into a dried particulate form using a spray dryer. An evaporator can be used to remove the bulk of the water in POME and to reduce the moisture content of the evaporated product to less than 70%. At this moisture content, the product becomes too viscous to pump through the evaporator. Spray dryers can handle viscous products very well. For this reason, a spray dryer is advantageously used to concentrate the concentrated liquid biofertilizer further to a dried product having a moisture content of about 0%.
Drying of the mixed biofertilizer, produced by mixing the cake discharged from the mechanical separation means with the concentrated liquid biofertilizer from the evaporation means, may be achieved using a drying means that is adopted for drying materials having high solids content. The drying of the mixed biofertilizer is advantageously carried out using a rotary dryer or a paddle dryer.
The condensate may be treated biologically, chemically (for example using biocides), physically (for example using microfilters, ultrafilters, nanonlters, reverse osmosis or granular activated carbon filters), or a combination thereof, and recycled for use in the palm oil mill.
The condensate that is not recycled back to the palm oil mill can be treated biologically using a small effluent treatment plant, such as a sequencing batch reactor (SBR) or membrane bioreactor (MBR), before it is discharged.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 illustrates schematically one preferred embodiment of the present invention, wherein the liquor from anaerobic treatment of POME is utilized to produce the concentrated liquid biofertilizer that may subsequently be dried. Figure 2 illustrates schematically another preferred embodiment of the present invention, wherein the liquor from anaerobic treatment of POME is utilized to produce the concentrated liquid biofertilizer and the cake discharged from the mechanical separation step is subsequently mixed with the concentrated liquid biofertilizer to produce a mixed biofertilizer. Figure 3 illustrates schematically yet another preferred embodiment of the present invention, wherein the liquor from aerobic treatment of POME is utilized to produce the concentrated liquid biofertilizer that may subsequently be dried.
Figure 4 illustrates schematically still yet another preferred embodiment of the present invention, wherein the liquor from aerobic treatment of POME is utilized to produce the concentrated liquid biofertilizer and the cake discharged from the separation step is subsequently mixed with the concentrated liquid biofertilizer to produce a mixed biofertilizer.
In describing the preferred embodiments of the present invention, which is illustrated in the drawings, specific terminology will be resorted to for the sake of clarity. However, it is not intended that the invention be limited to the specific terms so selected and it is to be understood that each specific term includes all technical equivalents which operate in a similar manner to accomplish a similar purpose.
MODE(S) FOR CARRYING OUT THE INVENTION
Figure 1 illustrates schematically one preferred embodiment of the present invention, wherein the liquor from anaerobic treatment of palm oil mill effluent (POME) is utilized to produce the concentrated liquid biofertilizer that is subsequendy dried. The POME 200 is initially treated using an anaerobic digestion means 201 to break down organic matter (generally quantified as biological oxygen demand or BOD) using microorganisms. The liquor from anaerobic treatment of POME 203 is then treated using mechanical separation means 204 to remove suspended solids prior to evaporation. The use of the mechanical separation means 204 generates two phases. One phase is easily disposable cake 205 having moisture content less than 80% that can be utilized as a biofertilizer without any further treatment. Another phase is clarified liquor 206 containing mainly water, soluble solids and fine fibrous solids. Clarified liquor 206 is processed using evaporation means 207 to remove the bulk of the water and other volatile components that it contains in an energy-efficient manner to form concentrated liquid biofertilizer 209 and condensate 208 containing the volatile components. Concentrated liquid biofertilizer 209 may then be dried using drying means 210 to produce solid biofertilizer 211. Condensate 208 may be treated biologically, chemically, physically, or a combination thereof, and recycled for use in the palm oil mill, or otherwise it is treated biologically using a small effluent treatment plant before it is discharged. Figure 2 illustrates schematically another preferred embodiment of the present invention, wherein the liquor from anaerobic treatment of POME is utilized to produce the concentrated liquid biofertilizer and the cake discharged from the mechanical separation step is subsequendy mixed with the concentrated liquid biofertilizer to produce a mixed biofertilizer. The POME 300 discharged from palm oil mills is initially treated using a similar approach to the mode illustrated by Figure 1. In the mode illustrated by this Figure 2, concentrated liquid biofertilizer 309 is mixed with cake 305 to form mixed biofertilizer 311 instead of being dried. Mixed biofertilizer 311 may be further processed using drying means 312 to generate solid mixed biofertilizer 313. The drying method used will be different from the drying method used for drying the liquid biofertilizer due to the
higher solids content. Alternatively, mixed biofertilizer 311 may be utilized without further drying. It may subsequendy be mixed with one or more bulking materials and utilized as mulch.
Figure 3 illustrates schematically another preferred embodiment of the present invention, wherein the liquor from aerobic treatment of POME is utilized to produce the concentrated liquid biofertilizer that is subsequendy dried. The POME 400 discharged from palm oil mills is first treated using anaerobic digestion means 401 and aerobic digestion means 404 operating in series to break down organic matter (generally quantified as biological oxygen demand or BOD) using microorganisms. The liquor from the aerobic digestion means will have lower total solids and suspended solids content then the digestate from the anerobic digestion means. Its use as feed to the evaporation means will lead to less fouling problems. The liquor from aerobic treatment of POME 405 is treated using a similar approach to the mode illustrated by Figure 1 to produce concentrated liquid biofertilizer 411, which may then be dried using drying means 412 to produce solid biofertilizer 413.
Figure 4 illustrates schematically another preferred embodiment of the present invention, wherein the liquor from aerobic treatment of POME is utilized to produce the concentrated liquid biofertilizer and the cake discharged from the mechanical separation step is subsequently mixed with the concentrated liquid biofertilizer to produce a mixed biofertilizer. The POME 500 is first treated using anaerobic digestion means 501 and aerobic digestion means 504 operating in series using a similar approach to the mode illustrated by Figure 3. The aerobic liquor 505 from aerobic treatment of POME is then further treated using a similar approach to the mode illustrated by Figure 2 to generate mixed biofertilizer 513. Mixed biofertilizer 511 may be further processed using drying means 514 to generate solid mixed biofertilizer 515. Mixed biofertilizer 511 may subsequendy be mixed with one or more bulking materials and utilized as mulch.
In all of the abovementioned modes for carrying out the invention, evaporation may be carried out by using a falling film evaporator, a forced circulation evaporator, a dynamic scraped surface evaporator or an evaporator using a combination of these
evaporation methods. The use of the falling film evaporation method should be limited to the first one or two stages only of a multiple-effect evaporator system when the viscosity of the product being evaporated is still sufficiently low. The use of scraped surface evaporation or forced circulation evaporation methods will minimize fouling of the evaporator as the concentration of solids increases. The scraped surface evaporation method is advantageously used as the final evaporation stage of a multiple-effect evaporation system to achieve very high concentration of solids. The use of a mechanical separation means prior to evaporation to remove a significant portion of the suspended solids implies that the viscosity of the feed to the evaporator will be quite low compared to the viscosity of raw POME in a conventional mill.
In the modes for carrying out the invention illustrated by Figures 1 and 3, the concentrated liquid biofertilizer discharged from the evaporator may be concentrated further by drying to make it easier to handle and to rninirnize storage and transportation costs. Drying is ideally carried out using a spray dryer. Because spray drying is a relatively energy-intensive method for removing water, the evaporation means is used for removing the bulk of the water in POME to generate a product having moisture content less than 70%. At this moisture content, the viscosity of the product becomes too high for pumping through the evaporator. The spray dryer is therefore advantageously used to concentrate the concentrated liquid biofertilizer further to a dried product having a moisture content of about 10%.
In the modes for carrying out the invention illustrated by Figures 2 and 4, the mixed biofertilizer may be dried by using a drying means adopted for drying materials having high solids content. The drying of the mixed biofertilizer is advantageously carried out using a rotary dryer or a paddle dryer. Alternatively, the mixed biofertilizer may subsequendy be mixed with one or more bulking materials, such as empty fruit bunches, decanter cake, bunch ash, boiler ash, palm fruit fibre, palm kernel expeller cake or saw dust, and utilized as mulch without further drying.
The modes or embodiments of the invention described herein are only meant to facilitate understanding of the invention and should not be construed as limiting the
invention to those modes or embodiments only. Those skilled in the art will appreciate that the modes or embodiments of the invention described herein are susceptible to variations and modifications other than those specifically described. It is to be understood that the invention includes all such variations and modifications which fall within the scope of the inventive concept thereof.
INDUSTRIAL APPLICABILITY
The present invention finds ready industrial applicability in the palm oil industry as it is a method for converting the effluent discharged from palm oil mills from a product having very litde economic value and requiring substantial investment for its treatment to comply with regulations on discharge standards to a product that can be used as a biofertilizer. The invention provides a method for addressing the problems faced with the utilization of the effluent discharged from palm oil mills as a biofertilizer to achieve zero discharge of liquid effluent. In essence it is a modern green technology approach to oil palm milling as it addresses the problem of the high volume of effluent discharged from palm oil mills by utilizing the effluent to generate a useful by-product of economic value.
Claims
A method for producing a concentrated liquid biofertilizer comprising the steps of:
(a) partially digesting (201, 301, 401 and 404, 501 and 504) palm oil mill effluent from palm oil milling process to produce a partially treated effluent (203, 303, 405, 505);
(b) separating solids in the partially treated effluent using mechanical separation means (204, 304, 406, 506) to produce a cake (205, 305, 407, 507) and a clarified liquor (206, 306, 408, 508);
(c) evaporating the clarified liquor (206, 306, 408, 508) using evaporation means (207, 307, 409, 509) to an extent sufficient to produce the concentrated liquid biofertilizer (209, 309, 411, 511) and a condensate (208, 308, 410) containing evaporated components as by-product.
A method according to Claim 1, wherein the partial digestion of palm oil mill effluent is effected using anaerobic digestion means (201, 301) and the partially treated effluent is anaerobic liquor (203, 303).
A method according to Claim 1 , wherein the partial digestion of palm oil mill effluent is effected using a combination of anaerobic digestion means (401, 501) and aerobic digestion means (404, 504) and the partially treated effluent is aerobic liquor (405, 505).
4. A method according to Claim 1, wherein the concentrated liquid biofertilizer (209, 411) is dried using drying means (210, 412) to produce a solid biofertilizer (211,
5. A method according to Claims 1 and 4, wherein the cake (205, 407) is directly utilized as a biofertilizer.
6. A method according to Claim 1, wherein the concentrated liquid biofertilizer (309, 511) is mixed (310, 512) with the cake (305, 507) to produce a mixed biofertilizer (311 , 513).
7. A method according to Claim 6, wherein the mixed biofertilizer (311, 513) is dried using a drying means (312, 514) to produce a solid mixed biofertilizer (313, 515).
8. A method according to Claim 6, wherein the mixed biofertilizer (311 , 513) is combined with one or more bulking materials for use as mulch.
9. A method according to Claim 8, wherein the bulking material is empty fruit bunches, decanter cake, bunch ash, boiler ash, palm fruit fibre, palm kernel expeller cake or saw dust, or combination thereof.
10. A method according to Claim 1, wherein the evaporation means (207, 307, 409, 509) employs forced circulation evaporation technique or scraped surface evaporation technique.
11. A method according to Claim 1 , wherein the evaporation means (207, 307, 409, 509) employs a combination of falling film evaporation technique and forced circulation evaporation technique in series.
12. A method according to Claim 1, wherein the evaporation means (207, 307, 409, 509) employs a combination of falling film evaporation technique and scraped surface evaporation technique in series.
13. A method according to Claim 1, wherein the evaporation means (207, 307, 409, 509) employs a combination of forced circulation evaporation technique and scraped surface evaporation technique in series.
14. A method according to Claim 1 , wherein the mechanical separation means (204, 304, 406, 506) is a two-phase decanting centrifuge, a belt press, a filter press or a multi-disk screw press.
15. A method according to Claims 1 or 14, wherein the partially treated effluent (203, 303, 405, 505) is chemically dosed to assist in the flocculation of solids to improve the separation of solids by the mechanical separation means (204, 304, 406, 506).
16. A method according to Claim 4, wherein the drying means (210, 412) is a spray dryer.
17. A method according to Claim 7, wherein the drying means (312, 514) is a rotary dryer or a paddle dryer.
18. A method according to Claim 1, wherein at least a portion of the condensate (208, 308, 410) is treated biologically, chemically, physically, or a combination thereof, and recycled for use in the palm oil mill.
19. A method according to Claim 1, wherein at least a portion of the condensate (208, 308, 4 0) is treated biologically and discharged.
20. A method according to Claim 1, wherein the clarified liquor (206, 306, 408, 508) is chemically dosed to precipitate volatile organic and inorganic components contained therein.
21. A method according to Claim 18, wherein the chemical treatment consists of using biocides.
22. A method according to Claim 18, wherein the physical treatment consists of using microfilters, ultrafilters, nanofilters, reverse osmosis, or combination thereof.
23. A method according to Claim 18, wherein the physical treatment consists of using granular activated carbon filters.
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CN111925066A (en) * | 2020-08-20 | 2020-11-13 | 重庆大学 | Split type continuous operation micro-grid dynamic membrane bioreactor |
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JP2002186960A (en) * | 2000-12-19 | 2002-07-02 | Kyushu Inst Of Technology | Method for treating vegetable oil waste liquid and method for preparing fertilizer using components obtained by its method |
KR100938490B1 (en) * | 2008-04-24 | 2010-01-28 | 한국생명공학연구원 | Method for Preparing Biofertilizer Using Palm Oil Mill Wastage |
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