Process for Producing Lipids and Other Organic Compounds from Biomass

Abstract

Process for producing lipids and other organic compounds from biomass comprising the following steps: (a) subjecting said biomass to extraction, at room temperature, in the presence of at least one low-boiling point solvent, thereby obtaining a first organic phase comprising lipids and solvent, and a first slurry phase comprising carbohydrates and proteins; (b) subjecting the first organic phase obtained in said step (a) to evaporation of the solvent, obtaining a second organic phase comprising lipids and a third organic phase comprising solvent, which is recycled to said step (a); (c) subjecting the first slurry phase obtained in said step (a) to liquefaction operating at a temperature ranging from 100 C. to 200 C., preferably ranging from 110 C. to 180 C., at a pressure greater than the water vapor pressure at the temperature at which said liquefaction is carried out, for a time ranging from 30 minutes to 300 minutes, preferably ranging from 50 minutes to 270 minutes, thereby obtaining a second slurry phase comprising sugars, proteins and unconverted carbohydrates; (d) subjecting the second slurry phase obtained in said step (c) to separation, obtaining an aqueous phase comprising sugars and a wet solid phase comprising proteins and unconverted carbohydrates. The lipids thus obtained may be advantageously used in the production of biodiesel or green diesel that may be used, in turn, as such, or in mixtures with other fuels, for automotive transport. The aqueous phase comprising sugars and the wet solid phase comprising proteins and unconverted carbohydrates thus obtained may in turn be exploited.

Claims

1. Process for producing lipids and other organic compounds from a biomass comprising the following steps: (a) subjecting said biomass to extraction, at room temperature, in the presence of at least one low-boiling point solvent, thereby obtaining a first organic phase comprising lipids and solvent, and a first slurry phase comprising carbohydrates and proteins; (b) subjecting the first organic phase obtained in said step (a) to evaporation of the solvent, obtaining a second organic phase comprising lipids and a third organic phase comprising solvent, which is recycled to said step (a); (c) subjecting the first slurry phase obtained in said step (a) to liquefaction operating at a temperature ranging from 100 C. to 200 C., at a pressure greater than the water vapor pressure at the temperature at which said liquefaction is carried out, for a time ranging from 30 minutes to 300 minutes, thereby obtaining a second slurry phase comprising sugars, proteins and unconverted carbohydrates; (d) subjecting the second slurry phase obtained in said step (c) to separation, obtaining an aqueous phase comprising sugars and a wet solid phase comprising proteins and unconverted carbohydrates.

2. Process for producing lipids and other organic compounds according to claim 1, wherein said extraction step (a) is carried out for a time period ranging from 2 hours to 12 hours.

3. Process for producing lipids and other organic compounds according to claim 1, wherein the low-boiling point solvent used in said step (a) is selected from the group consisting of: aliphatic hydrocarbons, aromatic hydrocarbons, ketones, halogenated hydrocarbons, and mixtures thereof.

4. Process for producing lipids and other organic compounds according to claim 1, wherein said biomass is treated by subjecting it to a preliminary homogenization, grinding or sizing process, before being subjected to said extraction step (a).

5. Process for producing lipids and other organic compounds according to claim 1, wherein said biomass is wet, said biomass having a water content greater than or equal to 50% by weight, relative to the total weight of said biomass.

6. Process for producing lipids and other organic compounds from a biomass comprising: (a.sub.1) subjecting said biomass to a drying process by operating at a temperature ranging from 30 C. to 60 C., at a pressure ranging from 50 mbar to 1 bar, for a time ranging from 1 hour and 48 hours, obtaining a dehydrated biomass; (a.sub.2) subjecting said dehydrated biomass to extraction, at room temperature, in the presence of at least one low-boiling point solvent, thereby obtaining a first organic phase comprising lipid and solvent, and a solid dehydrated phase comprising dehydrated carbohydrates and proteins; (b.sub.1) subjecting the first organic phase obtained in step (a.sub.2) to evaporation of the solvent, obtaining a second organic phase comprising lipids and a third organic phase comprising solvent, which is recycled to step (a.sub.2); (c.sub.1) subjecting the dehydrated solid phase obtained in said step (a.sub.2), after addition of water in such a quantity as to obtain a concentration of water ranging from 50% by weight to 90% by weight, relative to the total weight of said solid dehydrated phase, thereby obtaining a first slurry phase, to liquefaction operating at a temperature ranging from 100 C. to 200 C., at a pressure greater than the water vapor pressure at the temperature at which said liquefaction is carried out, for a time ranging from 30 minutes to 300 minutes, thereby obtaining a second slurry phase comprising sugars, protein and unconverted carbohydrates; (d.sub.1) subjecting the second slurry phase obtained in said step (c.sub.1) to separation, obtaining an aqueous phase comprising sugars and a wet solid phase comprising protein and unconverted carbohydrates.

7. Process for producing lipids and other organic compounds according to claim 6, wherein said extraction step (a.sub.2) is carried out for a time period ranging from 2 hours to 12 hours and the low-boiling point solvent is selected from the group consisting of aliphatic hydrocarbons, ketones, halogenated hydrocarbons and mixtures thereof.

8. Process for producing lipids and other organic compounds according to claim 6, wherein said biomass is treated by subjecting it to a preliminary homogenization, grinding or sizing process, before being subjected to said drying step (a.sub.1).

9. Process for producing lipids and other organic compounds according to claim 6, wherein said evaporation step (b.sub.1) is carried out at a temperature ranging from 30 C. to 60 C., at a pressure ranging from 50 mbar to 1 bar, for a time ranging from 1 hour to 48 hours.

10. Process for producing lipids and other organic compounds according to claim 6, wherein said liquefaction step (c.sub.1) is carried out in the presence of at least one inorganic acid; said inorganic acid being added to said first slurry phase obtained after addition of water to said dehydrated solid phase obtained in extraction step (a.sub.2), in a quantity ranging from 0.5% by weight to 2% by weight, relative to the total weight of said first slurry phase.

11. Process for producing lipids and other organic compounds according to claim 6, wherein said process comprises subjecting the wet solid phase comprising protein and unconverted carbohydrates obtained in separation step (d.sub.1) to dehydration.

12. Process for producing lipids and other organic compounds according to claim 6, wherein said process comprises (e) subjecting the wet solid phase comprising proteins and carbohydrates obtained in separation step (d.sub.1) to liquefaction at a temperature ranging from 220 C. to 350 C., at a pressure greater than water vapor pressure at the temperature at which said liquefaction is carried out for a time ranging from 30 minutes to 300 minutes, and obtaining a mixture including an oily phase consisting of bio-oil, a solid phase, an aqueous phase and a gaseous phase composed, mainly, of carbon dioxide (CO.sub.2).

13. Process for producing lipids and other organic compounds according to claim 6, wherein said process comprises (f) subjecting the aqueous phase comprising sugars obtained in said separation step (d.sub.1) to biological treatment and obtaining biogas, water and sludge.

14. Process for producing lipids and other organic compounds according to claim 1, wherein said evaporation step (b) is carried out at a temperature ranging from 30 C. to 60 C., preferably ranging from 35 C. to 55 C., at a pressure ranging from 50 mbar to 1 bar for a time ranging from 1 hour to 48 hours.

15. Process for producing lipids and other organic compounds according to claim 1, wherein said liquefaction step (c) is carried out in the presence of at least one inorganic acid; said inorganic acid being added to said first slurry phase obtained in said extraction step (a), in a quantity ranging from 0.5% by weight to 2% by weight, relative to the total weight of said first slurry phase.

16. Process for producing lipids and other organic compounds according to claim 1, wherein said process comprises subjecting the wet solid phase comprising protein and unconverted carbohydrates obtained in separation step (d) to dehydration.

17. Process for producing lipids and other organic compounds according to claim 1, wherein said process comprises (e) subjecting the wet solid phase comprising proteins and carbohydrates obtained in separation step (d) to liquefaction at a temperature ranging from 220 C. to 350 C., at a pressure greater than water vapor pressure at the temperature at which said liquefaction is carried out for a time ranging from 30 minutes to 300 minutes, and obtaining a mixture including an oily phase consisting of bio-oil, a solid phase, an aqueous phase and a gaseous phase composed, mainly, of carbon dioxide (CO.sub.2).

18. Process for producing lipids and other organic compounds according to claim 1, wherein said process comprises (e) subjecting the aqueous phase comprising sugars obtained in said separation step (d) to biological treatment and obtaining biogas, water and sludge.

19. Process for producing lipids and other organic compounds according to claim 3, wherein the low-boiling point solvent is selected from the group consisting of n-pentane, n-hexane, n-heptane, n-octane, kerosene, toluene, xylene, acetone, methyl ethyl ketone, ethyl acetate, propyl acetate, dichloromethane, chloroform and mixtures thereof.

20. Process for producing lipids and other organic compounds according to claim 19, wherein the low-boiling point solvent is selected from the group consisting of n-hexane, n-hexane/acetone (1/1, v/v) mixture, n-hexane/xylene (1/1, v/v) mixture, dichloromethane.

Description

EXAMPLE 1 (COMPARATIVE)

[0096] Liquefaction of Municipal Solid Waste (MSW) without Extraction with Solvent

[0097] A biomass (i.e. a sample of municipal solid waste called MSW-4), previously homogenized through a cutting mill, was loaded into an autoclave with a nominal volume of 1 liter: the homogenization allowed a product to be obtained having a creamy appearance with particle size less than 1 mm.

[0098] For analytical purposes, an aliquot of the homogenized material (500 g) was anhydrified through drying in a vacuum oven at 60 C., in order to determine the dry weight which was equal to 32.3% by weight. The macrocomposition of the homogenized material as such and after anhydrification is shown in Table 1. The analysis of the macrocomposition was carried out through the ISTISAN 1996/34 (National Institute of Health in Italy) methodology, as specified below: [0099] proteins (N6.25): ISTISAN 1996/34, pag. 13; [0100] humidity: ISTISAN 1996/34, pag. 7, Method B; [0101] ash ISTISAN 1996/34, pag. 77; [0102] lipids: ISTISAN 1996/34, pag. 41; [0103] carbohydrates: calculated to reach a total of 100.

TABLE-US-00001 TABLE 1 Lipids Carbohydrates Proteins Ash Water Total MSW-4 (%)* (%)* (%)* (%)* (%)* (%)* As such 8.9 11.7 7.6 1.6 70.1 100 Anhydrous 29.8 39.3 25.5 5.4 0 100 *% by weight with respect to the total weight of the homogenized material as such (As such) or with respect to the total weight of the homogenized material after anhydrification (Anhydrous).

[0104] After loading 400 g of homogenized biomass, as such, into the autoclave, nitrogen was blown for 5 minutes in order to remove the oxygen present. The autoclave was, then, pressurized with nitrogen setting 1 bara (absolute pressure) and, then, the heating ramp was activated and, at 180 C., agitation was started. After reaching the temperature of 310 C., everything was left, under agitation, at said temperature, for 1 hour, Subsequently, the autoclave was left to cool and upon reaching room temperature the gas phase was separated through depressurization. Then an aliquot of the aqueous phase as such (10 ml) was taken for the purpose of subjecting it to the analyses specified below: the results obtained are shown in Table 4. Subsequently, ethyl acetate (300 ml) was poured into the autoclave, which was closed again: everything was left, under agitation, at room temperature, for 3 hours. Subsequently, the autoclave was stopped and the suspension obtained was unloaded and filtered on paper (25 micron), to separate the solid phase (i.e. solid residue) from the aqueous phase and from the oily phase containing bio-oil. The solid residue recovered was washed on the filter and then subjected to drying in a vacuum oven, at 60 C., for 48 hours. The aqueous phase and the oily phase containing bio-oil were left to unmix in a separator funnel, obtaining: a heavier aqueous phase and a lighter solvent phase containing bio-oil which, after separation from the aqueous phase through filtration, was anhydrified with the addition of sodium sulfate (Na.sub.2SO.sub.4Aldrich), then filtered again and, after evaporation of the solvent in the rotary evaporator, it was weighed obtaining the weight of the bio-oil produced. The results obtained are shown in Table 2, in terms of % yield by weight both over the total weight of the homogenized material as such (Yield over as such) and over the total weight of the dry component of the homogenized material obtained after anhydrification (Yield over dry).

TABLE-US-00002 TABLE 2 Bio-oil Solid residue Aqueous Gas phase (%) (%) phase (%)* (%) Yield over as 11.6 6.5 78.1 3.8 such Yield over dry 36.0 20.2 32.1 11.7 *estimated by difference with respect to 100.

[0105] The samples thus obtained, i.e. bio-oil, aqueous phase and solid phase (i.e. solid residue) were analyzed using the following analytical methods.

Aqueous Phase

[0106] The light acid quantities (formic acid, propionic acid, acetic acid, succinic acid, butyric acid) were determined using a DIONEX BIOLC 4000 ion-exchange chromatography system provided with: [0107] PED (Pulsed Electrochemical Detector); [0108] chromatography column Ice-AS1 (diameter: 9 mm, length 250 mm); [0109] AMMS-IEC (Anion MicroMembrane Suppressor-Ion Exclusion Chromatography) with chemical regenerant for suppression with 5 mM tetrabutylammonium hydroxide (TBAOHAldrich); [0110] 50 l injection loop;
operating with isocratic elution using 0.4 mM heptafluorobutyric acid (Aldrich) as the eluent.

[0111] The quantities of alcohols (methanol, ethanol) were determined as follows. For that purpose, a sample of the aqueous phase was subjected to gas chromatography separation combined with a Flame Ionization Detector (FID) system, using a fused-silica capillary gas chromatography column: Supelcowax-10 (30 m0.32 mm ID) in the cross-linked phase, with a phase thickness of 0.5 m, applying the following operating conditions: [0112] temperature program: initial temperature: 40 C.; isotherm for 5 minutes; 10 C./min increase up to the temperature of 200 C.; [0113] FID temperature: 260 C.; [0114] air: 400 ml/min; [0115] hydrogen: 40 ml/min; [0116] injector: split/splitless in split mode with 30 ml/min split vent and temperature of 220 C.; [0117] injection volume: 1 l; [0118] carrier gas: helium 4 ml/min; [0119] internal standard: n-decane (Aldrich).

[0120] The quantities of sugars (glucose, mannose) were determined through HPAE (High Performance Anion Exchange) using a Thermo-Scientific Dionex ICS 5000 chromatography system provided with a PAD (Pulsed Amperometric Detector) which allows the target sugars present to be accurately determined, also at low concentrations, in aqueous samples with excellent signal/noise ratios, by applying the following operating conditions: [0121] analytical column: CarboPac PA100 Analytical (2 mm250 mm) (Dionex); [0122] pre-column: Carbopac PA100 guard (2 mm50 mm) (Dionex); [0123] eluents: (A) sodium hydroxide (NaOH) 100 mM; (B) sodium hydroxide (NaOH) 200 mM+0.6 mM sodium acetate (CH.sub.3COONa); [0124] flow rate: 0.250 ml/min; [0125] injection mode: PushSeqFull; [0126] column temperature: 30 C.; [0127] conductivity detector: PED (Pulsed Electrochemical Detector); [0128] working electrode: gold (Au) on polytetrafluoroethylene (PTFEAldrich).

Bio-Oil

[0129] The characterization of the bio-oil was carried out using an analytical protocol developed by combining various techniques. In fact, bio-oil has a complex composition, comparable to that of crude oil therefore its detailed characterization is not possible with a single analysis.

[0130] For the main compounds present in the oil, free fatty acids and amides variously substituted with these acids, their quantification was determined through gas chromatography-mass spectrometry (GC-MS) using SIM (Selected Ion Monitoring) which selectively allows their quantification, by operating as described by Chiaberge S. et al., in Energy & Fuels (2013), Vol. 27, pag. 1873-1880.

[0131] The content of other volatile compounds, such as alkyl-pyrrolidones, diketopiperazine, alkyl-phenols, esters of short chain acids, paraffins and olefins, were estimated based on the graph obtained from the aforementioned gas chromatography-mass spectrometry (GC-MS).

[0132] The content of alkyl aromatic compounds containing nitrogen and oxygen within the molecular structures was instead estimated by relating the data obtained through .sup.13C-HMR spectrometry and the data obtained through FTICR-MS (high-resolution Fourier-Transform Ion Cyclotron Resonance Mass Spectrometry), operating as described by Chiaberge S. et al., in Chem Sus Chem (2013), Vol. 6(1), peg. 160-167.

Solid Residue

[0133] The quantity of ash was determined according to the ISTISAN 1996/34 (National Institute of Health in Italy) standard method, pag. 77.

[0134] Table 3 shows the composition of the bio-oil obtained. From the data shown in Table 3 it may be deduced that the glycerides, which constitute almost all of the lipid fraction of the starting municipal solid waste (MSW), are almost totally hydrolyzed, while the fatty acids, deriving from the hydrolysis of the glycerides, largely form esters, amides, ketone compounds and, to a smaller extent, alkanes following decarboxylation reactions. Table 4 shows the organic component present in the aqueous phase. The sum of the carbon deriving from the quantities of acidic compounds and sugars deriving from the above analysis is equal to 7266 ppm with a TOC (Total Organic Carbon) value, determined according to the standard method CNR IRSA 5040 Man 29 2003, equal to 38000 ppm: this highlights that the aqueous phase contains numerous other organic compounds. On this point, it is to be noted that the nature of said other organic compounds, as stated in literature, prevalently consists of ketones, aldehydes, alcohols, alkyl-phenols, nitrogen heterocycles, which are not as easily biodegradable as sugary compounds.

[0135] The solid phase (i.e. solid residue) was found to contain 20% by weight of ash over the total weight of said residue and to have a calorific value of 24.5 MJ/kg, indicating a potential loss of carbon which instead of producing bio-oil leads to the formation of said solid phase (i.e. solid residue).

TABLE-US-00003 TABLE 3 (%)* Classes of compounds 11 Fatty acids (COOH with, on average, C.sub.16-C.sub.18 chains) 3 Fatty acid amides (CONH.sub.2/CONHR) 40 Compounds that contain at least one aromatic ring 43 Paraffins and olefins (average, C.sub.16 chains) Fatty acid ethyl and methyl esters Fatty acid hydroxy amides (e.g., ricinoleic acid) Various non-lipid acid amides Fatty acid amides with pentose or hexose derivatives Fatty acid amides with non-aromatic aminoacids (e.g., methionine) Ketone compounds on C.sub.16-C.sub.18 chains Alkyl cycloalkanes (e.g., alkyl-cyclohexanes) Alkyl cyclopentenones (alkyl: C.sub.6-C.sub.12) Steranes and sterols 3 Glycerols and others *% by weight with respect to the total weight of bio-oil.

TABLE-US-00004 TABLE 4 Aqueous phase Formates Acetates Propionates Butyrates Succinates Mannitol Glucose Alcohols TOC (total) ppm 92 10218 1175 626 1305 3422 253 494 17585 ppm of carbon 24 4086 571 342 531 1354 100 258 7266

EXAMPLE 2 (INVENTION)

[0136] Extraction of Lipids with Solvent or Mixture of Solvents [Step (a.sub.2)] from Dehydrated Municipal Solid Waste (MSW) and Evaporation of the Solvent [Step (b.sub.1)]

[0137] Table 6, Table 7 and Table 8 show the lipid yields obtained by subjecting to extraction in the presence of a solvent or of a mixture of solvents, three different biomasses, i.e. three different samples of municipal solid waste (MSW) called MSW-1, MSW-2 and MSW-3, previously homogenized as described in Example 1 and subsequently subjected to dehydration as reported below: the macrocompositions of said samples, obtained through the ISTISAN 1996/34 method reported in Example 1, are reported in Table 5.

TABLE-US-00005 TABLE 5 Proteins Lipids Carbohydrates Ash (%)* (%)* (%)* (%)* MSW-1 35.1 10.5 48 6.4 MSW-2 32 24.2 37.8 6 MSW-3 27.5 44.6 23.6 4.3 *% by weight with respect to the total weight of the homogenized and dehydrated sample.

[0138] For that purpose, 22.4 g of each sample were subjected to dehydration through a bland heat treatment (50 C.) and high vacuum (100 mbar), in a laboratory vacuum oven, for the required time to bring the sample to constant weight (10 hours). Subsequently, the dehydrated samples were placed in Falcon 15 ml conical-bottom tubes, in contact with the solvent or the mixture of solvents in a 2 to 1 ratio, in terms of solvent volume with respect to sample volume and the extraction was repeated 3 times. The extraction was carried out at room temperature with contact times of 8 hours, obtaining a first organic phase comprising lipids and solvent, and a dehydrated solid phase comprising carbohydrates and proteins. Said dehydrated solid phase was called MSW-1a for the MSW-1 sample, MSW-2a for the MSW-2 sample and MSW-3a for the MSW-3 sample.

[0139] The solvents used or the mixtures of solvents used are reported in the following tables: the mixture n-hexane (Aldrich)/acetone (Aldrich) is a 1/1 (v/v) mixture, the mixture n-hexane (Aldrich)/xylene (Aldrich) is a 1/1 (v/v) mixture.

[0140] At the end of the extraction, said first organic phase was subjected to evaporation and the solvent or the mixture of solvents was evaporated, in a laboratory vacuum oven, at a temperature of 50 C., under high vacuum (100 mbar) for the required time to bring the extract to a constant weight (5 hours). The lipids obtained were analyzed as reported below: Table 9, Table 10 and Table 11 show the results obtained. As may be deduced from Tables 9-11, the lipid composition is independent from the type of solvent used but depends exclusively on the starting sample. Furthermore, it is highlighted that most of the extracts are neutral triglycerides (triacylglycerides) while a small part are free fatty acids unlike the bio-oil reported in Table 3.

[0141] The lipids obtained were analyzed using the following analytical methods.

[0142] The quantities of fatty acids, of mono-, di- and tri-acylglycerides present in the samples being examined were carried out by internal standardization after silanizating the sample itself using N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFAAldrich) as a silanizating agent. For the aforementioned purpose, said quantities were determined through gas chromatography equipped with a Flame Ionization Detector (FID) system, using a fused-silica capillary gas chromatography column: SupelcoPetrocol EX28787 (5 m0.53 mm ID) in the cross-linked phase, with a phase thickness of 0.5 m, applying the following operating conditions: [0143] temperature program: initial temperature: 50 C.; isotherm for 2 minutes; 10 C./min increase up to the temperature of 350 C.; [0144] FID temperature: 350 C.; [0145] air: 400 ml/min; [0146] hydrogen: 35 ml/min; [0147] injector: split/splitless in split mode with 30 ml/min split vent and temperature of 220 C.; [0148] injection volume: 1 l; [0149] carrier gas: helium 5 ml/min; [0150] internal standard: n-decane.

TABLE-US-00006 TABLE 6 MSW-1 lipid yield (%)* n-hexane 40.46 n-hexane/acetone 40.95 n-hexane/xylene 40.21 dichloromethane 40.38 *% by weight with respect to the total weight of lipids contained in the homogenized and dehydrated sample after extraction.

TABLE-US-00007 TABLE 7 MSW-2 lipid yield (%)* n-hexane 24.15 n-hexane/acetone 24.44 n-hexane/xylene 23.89 dichloromethane 24.22 *% by weight with respect to the total weight of lipids contained in the homogenized and dehydrated sample after extraction.

TABLE-US-00008 TABLE 8 MSW-3 lipid yield (%)* n-hexane 10.44 n-hexane/acetone 10.51 n-hexane/xylene 10.31 dichloromethane 10.50 *% by weight with respect to the total weight of lipids contained in the homogenized and dehydrated sample after extraction.

TABLE-US-00009 TABLE 9 MSW-1 n- hexane/ n-hexane/ n-hexane acetone xylene dichloromethane (%)* (%)* (%)* (%)* C.sub.16 1.29 1.31 1 1.11 C.sub.18 2 1.99 2.12 2.12 monoacylglycerides 0.24 0.23 0.25 0.23 diacylglycerides 7.48 7.42 7.51 7.67 triacylglycerides 86.84 86.94 86.92 86.68 others 2.15 2.11 2.2 2.19 *% by weight with respect to the total weight of lipids obtained after extraction.

TABLE-US-00010 TABLE 10 MSW-2 n- hexane/ n-hexano/ n-hexane acetone xylene dichloromethane (%)* (%)* (%)* (%)* C.sub.16 1.27 1.28 1.2 1.15 C.sub.18 2 2 2.2 2.1 monoacylglycerides 0.25 0.24 0.28 0.3 diacylglycerides 5.49 5.35 5.3 5.22 triacylglycerides 88.81 88.91 88.9 89.18 others 2.18 2.22 2.12 2.05 *% by weight with respect to the total weight of lipids obtained after extraction.

TABLE-US-00011 TABLE 11 MSW-3 n- n- n- hexane/ hexane hexane/ xylene % by acetone % by dichloromethane weight % by weight weight % by weight C.sub.16 3.99 5.12 4.05 4.49 C.sub.18 14.68 14.08 14.92 15.01 monoacylglycerides 3.1 2.77 2.99 3.37 diacylglycerides 2.1 2 2.2 2.19 triacylglycerides 74.9 74.71 74.74 73.81 others 1.23 1.33 1.1 1.05 *% by weight with respect to the total weight of lipids obtained after extraction.

EXAMPLE 3 (INVENTION)

[0151] Extraction of Lipids with Solvent or Mixture of Solvents [Step (a)] from Municipal Solid Waste (MSW) as Such and Evaporation of the Solvent [Step (b)]

[0152] The extraction of lipids with an n-hexane/acetone (1/1, v/v) mixture was carried out using the same sample of municipal solid waste (MSW) called MSW-2 as such (i.e. wet, without subjecting it to dehydration as described in Example 2): said sample had a water content equal to 67.5% by weight with respect to the total weight of the sample.

[0153] For that purpose, 22 g of the sample were placed in Falcon 50 ml conical-bottom tubes, in contact with the solvent or the mixture of solvents in a 2 to 1 ratio, in terms of solvent volume with respect to sample volume and the extraction was repeated 3 times. The extraction was carried out at room temperature with contact times of 8 hours, obtaining a first organic phase comprising lipids and solvent, and a first slurry phase comprising carbohydrates and proteins.

[0154] At the end of the extraction, said first organic phase was subjected to evaporation and the n-hexane (Aldrich)/acetone (Aldrich) mixture was evaporated, at a temperature of 50 C., under high vacuum (100 mbar) for a sufficient amount of time to bring the extract to a constant weight (5 hours): the lipids obtained were analyzed as reported above.

[0155] The lipid yield obtained is equal to 24.12%: as may be seen from the comparison with Table 7 reported above, the lipid yield does not vary with respect to the extraction of lipids on the dehydrated sample.

[0156] Furthermore, as may be deduced from Table 12, the composition of lipids does not vary either with respect to the extraction of lipids on the dehydrated sample.

TABLE-US-00012 TABLE 12 n-hexane/acetone (%)* C.sub.16 1.09 C.sub.18 1.98 monoacylglycerols 0.03 diacylglycerols 5.84 triacylglycerols 89.6 others 1.47 *% by weight with respect to the total weight of lipids obtained after extraction.

EXAMPLE 4

[0157] Liquefaction of the Dehydrated Solid Phase [Step (c.sub.1)] and Separation [Step (d.sub.1)]

[0158] To the dehydrated solid phase (MSW-2a) (5.5 g) obtained after extraction of the lipids reported in Example 2, whose composition, determined according to the methodologies reported above, is as follows (% by weight with respect to the total weight of the sample): [0159] proteins: 42.2%; [0160] carbohydrates: 49.9%; [0161] ash 7.9%;

[0162] water was added in a quantity such as to obtain a concentration of water equal to 64% by weight with respect to the total weight of said dehydrated solid phase, obtaining a first slurry phase. Subsequently, sulfuric acid was added in a quantity such as to obtain a concentration of sulfuric acid equal to 1% by weight with respect to the total weight of said first slurry phase, whose composition, determined according to the methodologies reported above, is reported in Table 13.

TABLE-US-00013 TABLE 13 Proteins Carbohydrates Ash Water Acid (%)* (%)* (%)* (%)* (%)* 14.9 17.3 2.8 64.0 1.0 *% by weight with respect to the total weight of the first slurry phase.

[0163] Subsequently, everything was subjected to liquefaction, in a 20 ml stainless steel autoclave, operating at a temperature of 160 C., for a time of 90 minutes, obtaining a second slurry phase comprising sugars, proteins and unconverted carbohydrates. Said second slurry phase was subjected to separation by centrifugation, obtaining a wet solid phase comprising proteins and unconverted carbohydrates and an aqueous phase comprising sugars.

[0164] Table 14 shows the composition of said wet solid phase, determined according to the methodologies reported above: from the reported data, it may be deduced that there is a considerable reduction in carbohydrate content with respect to that of the starting dehydrated solid phase (MSW-2a).

TABLE-US-00014 TABLE 14 Proteins Carbohydrates Ash (%)* (%)* (%)* 75.0 10.7 14.3 *% by weight with respect to the total weight of the wet solid phase.

EXAMPLE 5

[0165] Liquefaction of the Wet Solid Phase [Step (e)]

[0166] To the wet solid phase comprising proteins and unconverted carbohydrates obtained in Example 4, demineralized water was added in a quantity such as to obtain a water concentration equal to 76% by weight with respect to the total weight of said wet solid phase obtaining the sample called MSW-2b.

[0167] Subsequently, said sample called MSW-2b was subjected to liquefaction in a 20 ml stainless steel autoclave, operating at 300 C., for 60 minutes. At the end of the reaction, the gas phase was separated by depressurization of the autoclave, while the mixture comprising an oily phase, a solid phase and an aqueous phase obtained, was subjected to separation by decantation obtaining bio-oil, a solid phase (Residue) and an aqueous phase: the results obtained are reported in Table 15, in terms of % yield by weight over the total wet solid phase.

TABLE-US-00015 TABLE 15 Bio-oil Residue Aqueous phase Gas phase (%) (%) (%) (%) 10.4 6.5 76.8 6.3

EXAMPLE 6

[0168] Liquefaction of the Wet Solid Phase [Step (e)] and Recycling of Water to Liquefaction

[0169] To the wet solid phase comprising proteins and unconverted carbohydrates obtained in Example 4, water deriving from the previous liquefaction was added in a quantity such as to obtain a water concentration equal to 76.3% by weight with respect to the total weight of said wet solid phase obtaining the sample called MSW-2c.

[0170] Subsequently, said sample called MSW-2c was subjected to liquefaction in a 20 ml stainless steel autoclave, operating at 300 C., for 60 minutes. At the end of the reaction, the gas phase was separated by depressurization of the autoclave, while the mixture comprising an oily phase, a solid phase and an aqueous phase obtained, was subjected to separation by decantation obtaining bio-oil, a solid phase (Residue) and an aqueous phase: the results obtained are reported in Table 16, in terms of % yield by weight over the total wet solid phase.

TABLE-US-00016 TABLE 16 Bio-oil Residue Aqueous phase Gas phase (%) (%) (%) (%) 10.5 6.4 76.8 6.3

[0171] From the comparison with Example 5 (Table 15) it may be deduced that the recycling of process water does not cause any reduction in terms of bio-oil yield produced.