WO2023227899A1

WO2023227899A1 - A process for separating a mixed waste stream

Info

Publication number: WO2023227899A1
Application number: PCT/GB2023/051382
Authority: WO
Inventors: Fergal BYRNE; James Clark; James Comerford
Original assignee: Addible Ltd
Priority date: 2022-05-26
Filing date: 2023-05-25
Publication date: 2023-11-30
Also published as: GB202207809D0

Abstract

A recycling plant (1) includes a reaction vessel (3) for receiving a mixed waste stream (2), and a plurality of holding vessels (4) for holding multiple different types of organic solvents. An optimiser (7) determines which of the possible organic solvents would be optimum, and what amount of the organic solvents would be optimum to treat the waste stream (2). A controller (6) controls passage of the mixed waste stream (2) into the reaction vessel (3), and controls the amount of each of the optimum organic solvents passed from the holding vessels (4) into the reaction vessel (3). The mixed waste stream (2) and the organic solvents are maintained in the reaction vessel (3) under defined reaction conditions for a defined reaction time to separate components in the mixed waste stream (2). The controller (6) also controls passage of the organic solvents (5) out of the reaction vessel (3) with plastic additives dissolved within the organic solvents (5).

Description

A process for separating a mixed waste stream

The present invention relates to a process, a system, and a computer program product for at least partially separating components of a mixed waste stream.

Waste recycling is a large, global market with billions of tonnes of waste processed annually. Despite the increase in recycling activity year on year, there are still many complex waste streams which are difficult or impossible to recycle in an environmentally friendly manner.

There is therefore a need for an improved process for recycling complex waste streams with minimal environmental impact.

According to a first aspect of the present invention there is provided a process for at least partially separating components of a mixed waste stream, the process comprising the steps of: receiving a mixed waste stream, obtaining information on a type of the mixed waste stream, determining one or more optimum organic solvents based on the type of the mixed waste stream, obtaining the one or more optimum organic solvents, and contacting the mixed waste stream with the one or more optimum organic solvents to at least partially separate one or more components in the mixed waste stream.

By separating the components of the waste stream, the process of the invention is able to recycle even complex waste streams. In particular by contacting the mixed waste stream with the organic solvents, it is possible to selectively remove components from even complex waste streams for ease of recycling.

By analysing the type of the mixed waste stream, an optimum organic solvent may be selected to achieve effective recycling while ensuring an environmentally friendly solution. A class of the organic solvent may be at least one of carboxylic acid, carboxylic acid/alcohol, carboxylic acid/aldehyde, acyclic carbonate, alcohol, aromatic ether, bicyclic ketone, cyclic carbonate, ester, ester/alcohol, ester/ketone, ether, fluorinated alcohol, furan, ketone, lactone, nitrile, polyol, sulfoxide, and water. The organic solvent may comprise at least one of acetic acid, lactic acid, formic acid, dimethyl carbonate, 1 -butanol, 2-propanol, ethanol, methanol, t-butanol, anisole, cyrene, propylene carbonate, ethyl acetate, methyl acetate, methyl pivalate, n-butyl acetate, t-butyl acetate, ethyl lactate, butyl levulinate, 2- methyltetrahydrofuran (2-MeTHF), 2,2,5,5-tetramethyloxolane (TMO), hexafluoroisopropanol (HFIPA), 2,5-dimethylfuran, 2-methylfuran, 2-butanone, acetone, cyclopentanone, gammavalerolactone, acetonitrile, glycerol, dimethyl sulfoxide (DMSO), and water.

The organic solvent may comprise a single organic solvent compound. The organic solvent may comprise a mixture of two or more organic solvent compounds (e.g., a mixture of three, four, five, six, seven, eight, nine, ten, or more organic solvent compounds).

The mixed waste stream may comprise one or more materials to be recycled and one or more plastic additives. The material to be recycled may comprise at least one of polyethylene terephthalate (PET), high density polyethylene (HDPE), low density polyethylene (LDPE), polypropylene (PP), polyvinyl chloride (PVC), polyvinylidene dichloride (PVDC), polychlorotrifluoroethylene (PCTFE), acrylonitrile butadiene styrene (ABS), polyamide (PA), polystyrene (PS), polylactic acid (PLA), melamine, styrene butadiene rubber (SBR), natural rubber, nitrile butadiene rubber (NBR), cardboard (paper), ethylene-vinyl acetate (EVA), and aluminum foil. Upon contact of the mixed waste stream with the one or more organic solvents, the material to be recycled may be dissolved by the one or more organic solvents, or the material to be recycled may be swollen by the one or more organic solvents, or the material to be recycled may have no interaction with the one or more organic solvents to at least partially separate the one or more components in the mixed waste stream.

In the process of the invention dissolving refers to selective dissolution of the one or more materials to be recycled or polymer components, allowing the non-dissolved components to be filtered off and separated. After the other non-dissolved components have been filtered off, the dissolved materials to be recycled or polymer components may then be precipitated out of solution by adding a counter-solvent. Any additives remain in the solution, thus retrieving a pure solid polymer. The additives may also be removed from solution at a later stage as required, for example by evaporating the solvent. In the process of the invention swelling refers to when a material to be recycled or polymer component does not interact with a solvent by a sufficient extent to dissolve the material or polymer component. Instead the solvent partially interacts with the material or polymer component resulting in swelling of the material or polymer component. The effect of swelling is that additives may be easily removed from a swollen material or polymer component. Foil or paper based components may separate easily from a swollen polymer. The requirement for a counter-solvent is eliminated with an associated reduction in cost.

The plastic additive may comprise at least one of a stabilising agent, compatibilizer, antioxidant, antistatic agent, flame retardant, lubricant, plasticiser, antimicrobial agent, colouring agent, impact modifier, filler, reinforcement, blowing agent, fragrance, coupling agent, and residual catalyst from production.

The filler may be a clay or an inorganic salt. The residual catalyst may be a polymerisation catalyst.

Upon contact of the mixed waste stream with the one or more organic solvents, the plastic additive may be dissolved in the one or more organic solvents to at least partially separate the one or more components in the mixed waste stream.

The accumulation of additives in recycled plastics is a considerable problem which the recycling industry is currently facing. With existing recycling technology, a plastic may only be recycled a very small number of times before the number and variety of additives renders the material unsuitable for further recycling, for example because the recycled material is too weak, or has too much colour, or the like. By removing the additives, the process of the invention enables the material to be recycled multiple times, and allows indefinite recycling of the particular material or polymer component.

The process may comprise the step of receiving user input data on the type of the mixed waste stream.

The process may comprise the step of determining an optimum amount of each of the one or more optimum organic solvents based on the type of the mixed waste stream. In this manner the recycling process may be closely controlled to optimise the separation of the components in the waste stream. The process may comprise the steps of: identifying molecular solubility parameter data of the components of the mixed waste stream, and identifying molecular solubility parameter data of a set of candidate organic solvents, wherein the one or more optimum organic solvents are determined based on the molecular solubility parameter data of the mixed waste stream and the molecular solubility parameter data of the set of candidate organic solvents.

The parameters of the solvent are chosen to specifically target one or more components of the waste stream, for example by dissolution or by swelling.

The process may comprise the steps of: generating a computational model representation of the mixed waste stream and the set of candidate organic solvents in a vector space based on the molecular solubility parameter data, and determining a vector distance between the representation of the mixed waste stream and the representation of each candidate organic solvent in the set of candidate organic solvents, wherein the one or more optimum organic solvents and the optimum amount of each of the one or more optimum organic solvents are determined based on the vector distances.

In this manner the most suitable organic solvent is chosen for a particular type of waste stream.

The molecular solubility parameter data may comprise at least one of dispersion-forces data, polarity data, and hydrogen-bonding data.

The boiling points of the candidate organic solvents may also be used to select the most suitable organic solvent. The process may comprise the steps of: controlling reception of the mixed waste stream into a reaction vessel, and controlling passage of the one or more organic solvents from one or more holding vessels into the reaction vessel to contact the mixed waste stream.

The process may comprise the step of controlling the amount of each of the one or more organic solvents passed from the one or more holding vessels into the reaction vessel. In this way the recycling process may be closely monitored to optimise the separation of the components in the waste stream.

The process may comprise the step of maintaining the mixed waste stream and the one or more organic solvents in the reaction vessel under defined reaction conditions for a defined reaction time to at least partially separate the one or more components in the mixed waste stream. In this manner the recycling process may be closely controlled to optimise the separation of the components in the waste stream.

The process may comprise the step of engaging one or more mechanical elements with the mixed waste stream in the reaction vessel to at least partially separate the one or more components in the mixed waste stream. The mechanical separation acts as a further means in addition to the solvent separation to remove the components from the waste stream. The process may comprise the step of controlling passage of the one or more organic solvents from the reaction vessel with at least some of the one or more plastic additives dissolved in the one or more organic solvents.

The process may be a computer-implemented process. The process may be a process for solvent recycling.

According to a second aspect of the present invention there is provided a system for at least partially separating components of a mixed waste stream, the system comprising: a reaction vessel for receiving a mixed waste stream, an interface to obtain information on a type of the mixed waste stream, an optimiser to determine one or more optimum organic solvents based on the type of the mixed waste stream, and one or more holding vessels for the one or more optimum organic solvents, the one or more holding vessels being connected in communication with the reaction vessel to pass the one or more optimum organic solvents into the reaction vessel to contact the mixed waste stream to at least partially separate one or more components in the mixed waste stream.

By separating the components of the waste stream, the system of the invention is able to recycle even complex waste streams. In particular by contacting the mixed waste stream with the organic solvents, it is possible to selectively remove components from even complex waste streams for ease of recycling.

By analysing the type of the mixed waste stream, an optimum organic solvent may be selected to achieve effective recycling while ensuring an environmentally friendly solution.

The interface may be configured to receive user input data on the type of the mixed waste stream.

The optimiser may be configured to determine an optimum amount of each of the one or more optimum organic solvents based on the type of the mixed waste stream. In this manner the recycling process may be closely controlled to optimise the separation of the components in the waste stream.

The optimiser may be configured to: identify molecular solubility parameter data of a mixed waste stream, identify molecular solubility parameter data of a set of candidate organic solvents, and determine the one or more optimum organic solvents based on the molecular solubility parameter data of the mixed waste stream and the molecular solubility parameter data of the set of candidate organic solvents. The optimiser may be configured to: generate a computational model representation of a mixed waste stream and a set of candidate organic solvents in a vector space based on the molecular solubility parameter data, determine a vector distance between the representation of the mixed waste stream and the representation of each candidate organic solvent in the set of candidate organic solvents, and determine the one or more optimum organic solvents and the optimum amount of each of the one or more optimum organic solvents based on the vector distances.

The system may comprise a controller to control the amount of each of the one or more organic solvents passed from the one or more holding vessels into the reaction vessel. In this way the recycling process may be closely monitored to optimise the separation of the components in the waste stream. The controller may be configured to control passage of the one or more organic solvents from the reaction vessel with one or more plastic additives dissolved in the one or more organic solvents.

The system may comprise one or more mechanical elements to engage with a mixed waste stream in the reaction vessel to at least partially separate the one or more components in the mixed waste stream. The mechanical separation acts as a further means in addition to the solvent separation to remove the components from the waste stream. The mechanical element may comprise at least one of a screw element and a filter element.

The system may be a recycling plant.

According to a third aspect of the present invention there is provided a data processing system for at least partially separating components of a mixed waste stream, the system comprising a processor configured to perform the process of the first aspect of the invention. According to a fourth aspect of the present invention there is provided a computer program product comprising instructions capable of causing a computer system to perform the process of the first aspect of the invention when the computer program product is executed on the computer system. The computer program product may be embodied on a record medium, or a carrier signal, or a read-only memory.

Embodiments of the present invention will be described hereinafter, by way of example only, with reference to the accompanying drawings, in which:

Fig. 1 is a schematic illustration of a system according to the invention for at least partially separating components of a mixed waste stream, and

Fig. 2 is a flow diagram illustrating the system of Fig. 1 in use.

In the drawings like reference numerals refer to like parts.

Referring to the drawings, and initially to Fig. 1 thereof, there is illustrated a recycling plant system 1 according to the invention for at least partially separating components of a mixed waste stream 2.

The system 1 includes a reaction vessel 3 for receiving the mixed waste stream 2, a plurality of holding vessels 4 for holding multiple different types of organic solvents, a controller 6, and an optimiser 7.

The mixed waste stream 2 may include one or more materials to be recycled and one or more plastic additives. For example the material to be recycled may be polyethylene terephthalate (PET), high density polyethylene (HDPE), low density polyethylene (LDPE), polypropylene (PP), polyvinyl chloride (PVC), polyvinylidene dichloride (PVDC), polychlorotrifluoroethylene (PCTFE), acrylonitrile butadiene styrene (ABS), polyamide (PA), polystyrene (PS), polylactic acid (PLA), melamine, styrene butadiene rubber (SBR), natural rubber, nitrile butadiene rubber (NBR), cardboard (paper), ethylene-vinyl acetate (EVA), or aluminum foil. For example the plastic additive may be a stabilising agent, a compatibilizer, an antioxidant, an antistatic agent, a flame retardant, a lubricant, a plasticiser, an antimicrobial agent, a colouring agent, an impact modifier, a filler, a reinforcement, a blowing agent, a fragrance, a coupling agent, or a residual catalyst from production. Each of the organic solvents in the holding vessels 4 may be a single organic solvent compound, or may be a mixture of two or more organic solvent compounds. For example a class of the organic solvent may be carboxylic acid, carboxylic acid/alcohol, carboxylic acid/aldehyde, acyclic carbonate, alcohol, aromatic ether, bicyclic ketone, cyclic carbonate, ester, ester/alcohol, ester/ketone, ether, fluorinated alcohol, furan, ketone, lactone, nitrile, polyol, sulfoxide, or water. For example the organic solvent may be acetic acid, lactic acid, formic acid, dimethyl carbonate, 1 -butanol, 2-propanol, ethanol, methanol, t-butanol, anisole, cyrene, propylene carbonate, ethyl acetate, methyl acetate, methyl pivalate, n-butyl acetate, t-butyl acetate, ethyl lactate, butyl levulinate, 2-methyltetrahydrofuran (2-MeTHF), 2, 2,5,5- tetramethyloxolane (TMO), hexafluoroisopropanol (HFIPA), 2,5-dimethylfuran, 2- methylfuran, 2-butanone, acetone, cyclopentanone, gamma-valerolactone, acetonitrile, glycerol, dimethyl sulfoxide (DMSO), or water.

The optimiser 7 may be employed to determine which of the possible organic solvents in the holding vessels 4 would be optimum to separate the components of the mixed waste stream 2. The selection of the optimum organic solvent(s) is based on the type of the mixed waste stream 2. The information on the type of the mixed waste stream 2 may be input by a user 13 via a user interface or other suitable means. The optimiser 7 also determines what amount of each of the organic solvents would be optimum to be allowed to be passed into the reaction vessel 3 to separate the components of the mixed waste stream 2. The selection of the optimum amounts is based on the type of the mixed waste stream 2.

In this case the optimiser 7 identifies the molecular solubility parameter data of the mixed waste stream 2, and identifies the molecular solubility parameter data of each of the possible organic solvents in the holding vessels 4. The molecular solubility parameter data may be dispersion- forces data, polarity data, or hydrogen-bonding data. The optimiser 7 generates a computational model representation of the mixed waste stream 2 and each of the possible organic solvents in a vector space based on the molecular solubility parameter data. The optimiser 7 determines a vector distance between the representation of the mixed waste stream 2 and the representation of each of the possible organic solvents, and determines the optimum organic solvent(s) and the optimum amount of each of the organic solvent(s) based on the vector distances.

The holding vessels 4 are connected in communication with the reaction vessel 3 to allow the carefully selected optimum organic solvent(s) to be passed into the reaction vessel 3. The controller 6 may be employed to control the passage of the mixed waste stream 2 into the reaction vessel 3, and to control the amount of each of the optimum organic solvent(s) passed from the holding vessels 4 into the reaction vessel 3. In this manner the organic solvents may be brought into contact with the mixed waste stream 2 in the reaction vessel 3. The mixed waste stream 2 and the organic solvents are maintained in the reaction vessel 3 under defined reaction conditions, such as a defined pressure or a defined temperature, for a defined reaction time to separate components in the mixed waste stream 2. In this case upon contact of the mixed waste stream 2 with the organic solvents, the materials to be recycled may be dissolved by the organic solvents, or the materials to be recycled may be swollen by the organic solvents, or the materials to be recycled may have no interaction with the organic solvents. Upon contact of the mixed waste stream 2 with the organic solvents, the plastic additives are dissolved in the organic solvents. In this way the plastic additives and any other components are selectively removed from the mixed waste stream 2.

In further detail, the separation process involves contacting the mixed waste stream 2 with the organic solvent. The organic solvent may act to achieve separation by dissolution of one or more components, or swelling of one or more components, or little or no interaction with one or more components. By either dissolving, swelling or not interacting with a component, each component may be selectively removed from the mixture one or more at a time. In the case of additives, these may be dissolved in the solvent.

The system 1 includes mechanical elements to engage with the mixed waste stream 2 in the reaction vessel 3 to further aid in removing the components from the mixed waste stream 2. For example the mechanical element may be a screw element or a filter element. The controller 6 also controls passage of the organic solvents 5 out of the reaction vessel 3 with the plastic additives dissolved within the organic solvents 5.

The system 1 achieves solvent recycling by separating the components of the complex mixed waste stream 2, so that each component can be subsequently treated individually using other means. The complex waste stream 2 includes multiple components. For example multi-layer films with a LDPE layer, a paper layer and an aluminium foil layer, or blister packs for medicine with PVC, PVDC and aluminium foil. The system 1 is effective in recycling plastic additives present in the polymer.

The solvent may be metered into the reaction vessel 3 at the required amounts to carry out the separation. The reaction vessel 3 into which the waste 2 is added may include the mechanical separation capability. For example, a screw or a filter to help selectively remove waste from the mixture 2.

The organic solvent may be a pure solvent (single component), or a mixture of two or three pure solvents. The choice of solvent may be from one of the list in Table 1 of green solvents that may be used for separating waste. The organic solvents listed in Table 1 may carry out the role of dissolving or swelling different components of the waste stream 2. These organic solvents may be at least one of non-hazardous, non-toxic, not petroleum-derived, not environmentally polluting, and not atmospherically polluting. The selection of which solvents from the list to use for a particular waste stream may be performed with the assistance of an algorithm, for example software code to choose the relative amounts of each solvent to dissolve a target solute. A 3D graph of the solubility space may be used to predict what solvents are likely to dissolve or swell a solute. The optimum solvents may vary between waste streams and additives.

Table 1

Solvent Solvent class

1 Dimethyl Carbonate Acyclic carbonate

2 1 -Butanol Alcohol

3 2-Propanol Alcohol

4 Ethanol Alcohol

5 Methanol Alcohol

6 t-Butanol Alcohol

7 Anisole Aromatic ether

8 Gyrene Bicyclic ketone

9 Acetic Acid Carboxylic Acid

10 Lactic Acid Carboxylic Acid/Alcohol

11 Formic Acid Carboxylic Acid/Aldehyde

12 Propylene Carbonate Cyclic carbonate

13 Ethyl Acetate Ester

14 Methyl acetate Ester

15 Methyl Pivalate Ester

16 n-Butyl Acetate Ester

17 t-Butyl Acetate Ester

18 Ethyl Lactate Ester/Alcohol

19 Butyl Levulinate Ester/Ketone 20 2,2,5,5-Tetramethyloxolane (TMO) Ether

21 2-Methyltetrahydrofuran (2-MeTHF) Ether

22 Hexafluoroisopropanol (HFIPA) Fluorinated alcohol

23 2,5-Dimethylfuran Furan

24 2-Methylfuran Furan

25 2-Butanone Ketone

26 Acetone Ketone

27 Cyclopentanone Ketone

28 gamma-valerolactone Lactone

29 Acetonitrile Nitrile

30 Glycerol Polyol

31 Dimethyl sulfoxide (DMSO) Sulfoxide

32 Water Water

Example additive groups are listed in Table 2.

Table 2 - list of additive groups

Additive type

1 Stabilising agents

2 Compatibilizers

3 Antioxidants

4 Antistatic agents

5 Flame retardants

6 Lubricants

7 Plasticisers

8 Antimicrobial agents

9 Colouring agents

10 Impact modifiers

11 Fillers

12 Reinforcements

13 Blowing agents

14 Fragrances

15 Coupling agents

16 Residual catalyst from production

Example waste streams are listed in Table 3. Table 3 - List of waste materials

Material

1 Polyethylene terephthalate (PET)

2 Polyethylene (PE)

3 Polypropylene (PP)

4 Polyvinyl chloride (PVC)

5 Polyvinylidene dichloride (PVDC)

6 Polychlorotrifluoroethylene (PCTFE)

7 Acrylonitrile butadiene styrene (ABS)

8 Polyamide (PA)

9 Polystyrene (PS)

10 Polylactic acid (PLA)

11 Melamine

12 Styrene butadiene rubber (SBR)

13 Natural rubber

14 Nitrile butadiene rubber (NBR)

15 Cardboard (paper)

16 Aluminum foil

17 Ethylene-vinyl acetate (EVA)

In use, the controller 6 controls passage of the mixed waste stream 2 into the reaction vessel 3 (step 11 in Fig. 2). The holding vessels 4 hold the multiple different types of organic solvents. The user interface of the optimiser 7 receives information from the user 13 on the type of the mixed waste stream 2 (step 12 in Fig. 2). The optimiser 7 identifies the molecular solubility parameter data of the mixed waste stream 2, and identifies the molecular solubility parameter data of each of the possible organic solvents in the holding vessels 4 (step 14 in Fig. 2). The optimiser 7 generates a computational model representation of the mixed waste stream 2 and each of the possible organic solvents in a vector space based on the molecular solubility parameter data (step 15 in Fig. 2). The optimiser 7 determines a vector distance between the representation of the mixed waste stream 2 and the representation of each of the possible organic solvents, and determines the optimum organic solvents and the optimum amount of each of the organic solvents based on the vector distances (step 16 in Fig. 2). The controller 6 controls the amount of each of the optimum organic solvents passed from the holding vessels 4 into the reaction vessel 3 (step 17 in Fig. 2). The mixed waste stream 2 and the organic solvents are maintained in the reaction vessel 3 under the defined reaction conditions for the defined reaction time to separate the components in the mixed waste stream 2. Upon contact of the mixed waste stream 2 with the organic solvents, the materials to be recycled may be dissolved by the organic solvents, or the materials to be recycled may be swollen by the organic solvents, or the materials to be recycled may have no interaction with the organic solvents. Upon contact of the mixed waste stream 2 with the organic solvents, the plastic additives are dissolved in the organic solvents. In this way the plastic additives and any other components are selectively removed from the mixed waste stream 2.

The mechanical elements engage with the mixed waste stream 2 in the reaction vessel 3 to further aid in separating the components in the mixed waste stream 2 (step 18 in Fig. 2). The controller 6 controls passage of the organic solvents 5 out of the reaction vessel 3 with the plastic additives dissolved within the organic solvents 5 (step 19 in Fig. 2).

The following are example embodiments of the invention.

Example 1

A waste stream including a multi-layer film composed of polyvinyl chloride (PVC), aluminium foil, plasticiser additives, and ink, was shredded into flakes. A solubility screening process was carried out on the shredded waste stream using solvents from the Green Solvent Database (GSD) listed in Table 1 above to determine the behaviour of the multi-layer film when contacted with a range of solvents. Using the data obtained from the screening process, an optimal green solvent was computed from the GSD listed in Table 1 above. A blend of Solvent 13 as listed in Table 1 above (40%) and Solvent 14 as listed in Table 1 above (60%) in the GSD was determined to be the optimal solvent to 1 ) swell the polyvinyl chloride component, 2) dissolve the inks, 3) dissolve plasticiser additives, and 4) not interact with the aluminium foil. The solvent blend was metered into a 10 L reactor with overhead stirrer containing the shredded multi-layer barrier film and the mixture was stirred for 30 minutes at room temperature, then filtered. The solid residue consisted of flakes of swelled PVC which were free from plasticiser and ink, and aluminium foil. The solids were collected and could be separated by density. The filtrate was collected, and the solvent recovered by distillation for reuse. Example 2

A waste stream including a multi-layer film which is composed of polyethylene terephthalate (PET), aluminium foil, and a lacquer, was shredded into flakes. A solubility screening process was carried out on the shredded waste stream using solvents from the Green Solvent Database (GSD) listed in Table 1 above to determine the behaviour of the multilayer film when contacted with a range of solvents. Using the data obtained from the screening process, an optimal green solvent was computed from the GSD. A blend of Solvent 13 as listed in Table 1 above (90%) and Solvent 2 as listed in Table 1 above (10%) were determined to be the optimal solvent to 1 ) dissolve the lacquer, 2) not interact with the PET or aluminium foil, and 3) separate the PET and aluminium foil layers. The solvent blend was metered into a 10 L reactor with overhead stirrer containing the shredded multi-layer barrier film and the mixture was stirred for 10 minutes at room temperature, then filtered. The solid residue consisted of flakes of PET and aluminium foil. The solids were collected and could be separated by density. The filtrate was collected, and the solvent recovered by distillation for reuse. The distillation residue consisted of lacquer which was collected for reuse.

Example 3

A waste stream including a multi-layer film which is composed of polyethylene terephthalate (PET), a polyacrylate adhesive, cardboard, and inks, was shredded into flakes. A solubility screening process was carried out on the shredded waste stream using solvents from the Green Solvent Database (GSD) listed in Table 1 above to determine the behaviour of the multi-layer film when contacted with a range of solvents. Using the data obtained from the screening process, an optimal green solvent was computed from the GSD listed in Table 1 above. Solvent 20 as listed in Table 1 above was determined to be the optimal solvent to 1 ) dissolve the adhesive, 2) dissolve the inks, 3) not interact with the PET or cardboard, and 4) separate the PET and cardboard layers. The solvent was added to the shredded film and the mixture was stirred for 30 minutes at room temperature and filtered. The solid residue consisted of flaked PET and cardboard. The solids were collected and could be separated by density. The filtrate was collected, and the solvent recovered by distillation for reuse.

Example 4 A waste stream including a multi-layer film which is composed of polylactic acid (PLA), paper, and inks, was shredded into flakes. A solubility screening process was carried out on the shredded waste stream using solvents from the Green Solvent Database (GSD) listed in Table 1 above to determine the behaviour of the multi-layer film when contacted with a range of solvents. Using the data obtained from the screening process, an optimal green solvent was computed from the GSD listed in Table 1 above. Solvent 18 as listed in Table 1 above was determined to be the optimal solvent to 1 ) dissolve the PLA, 2) dissolve the inks, and 3) not interact with paper. The solvent was added to the shredded film and the mixture was stirred for 30 minutes at room temperature and filtered. The solid residue, which consisted of flaked paper, was collected. The filtrate consisted of dissolved PLA and inks. Addition of Solvent 5 as listed in Table 1 above precipitated PLA from solution while keeping the inks in solution. Precipitated PLA was filtered and collected, while the Solvents 5 and 18 as listed in Table 1 above were separated and recovered by distillation for reuse.

Example 5

A waste stream including PET food trays and bowls, bound to lidding film by a heat sealing adhesive, such as ethylene-vinyl acetate (EVA), was shredded into flakes. A solubility screening process was carried out on the shredded waste stream using solvents from the Green Solvent Database (GSD) listed in Table 1 above to determine the behaviour of the waste stream when contacted with a range of solvents. Using the data obtained from the screening process, an optimal green solvent was computed from the GSD listed in Table 1 above. Solvent 20 as listed in Table 1 above was determined to be the optimal solvent to 1 ) dissolve the EVA adhesive, 2) not interact with the PET tray flakes or lidding film, and 3) separate the PET tray flakes and lidding film layers. The Solvent 20 was added to the shredded waste stream and the mixture was agitated for at least 15 minutes at room temperature and filtered. The solid residue consisted of flakes of PET tray and lidding film. The solids were collected and separated by density. The filtrate was collected, and the Solvent 20 was recovered by distillation for reuse. The distillation residue consisted of EVA adhesive.

Example 6

A waste stream including a multi-layer barrier film consisting of PVC and PVDC layers was shredded into flakes. A solubility screening process was carried out on the shredded waste stream using solvents from the Green Solvent Database (GSD) listed in Table 1 above to determine the behaviour of the waste stream when contacted with a range of solvents. Using the data obtained from the screening process, an optimal green solvent was computed from the GSD listed in Table 1 above. A mixture of Solvent 28 (60%) and Solvent 20 (40%) was the optimal solvent mixture to 1) dissolve PVC component in 15 minutes, and 2) not interact with the PVDC component. The mixture of Solvent 28 and Solvent 20 was added to the shredded waste stream and heated to 60 °C and agitated for at least 15 minutes and filtered. The solid residue consisted of flakes of PVDC and was collected. The filtrate consisted of PVC dissolved in the solvent blend and was collected. The relative concentrations of the solvent blend was then modified to a mixture containing Solvent 28 (40%) and Solvent 20 (60%) by the addition of the corresponding quantity of Solvent 20. This resulted in the precipitation of PVC from the new solvent blend, which was removed by filtration and collected. The filtrate was collected, and the solvents were recovered by distillation for reuse. The distillation residue consisted of plastic additives.

Throughout the description and claims of this specification, the words “comprise” and “contain” and variations of them mean “including but not limited to” and they are not intended to (and do not) exclude other moieties, additives, components, integers or steps. Throughout the description and claims of this specification, the singular encompasses the plural unless the context otherwise requires. In particular, where the indefinite article is used, the specification is to be understood as contemplating plurality as well as singularity, unless the context requires otherwise.

Features, integers, characteristics or groups described in conjunction with a particular aspect, embodiment or example of the invention are to be understood to be applicable to any other aspect, embodiment or example described herein unless incompatible therewith. All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of the features and/or steps are mutually exclusive. The invention is not restricted to any details of any foregoing embodiments. The invention extends to any novel one, or novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

The reader’s attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

Claims

CLAIMS:

1 . A process for at least partially separating components of a mixed waste stream, the process comprising the steps of: receiving a mixed waste stream, obtaining information on a type of the mixed waste stream, determining one or more optimum organic solvents based on the type of the mixed waste stream, obtaining the one or more optimum organic solvents, and contacting the mixed waste stream with the one or more optimum organic solvents to at least partially separate one or more components in the mixed waste stream.

2. A process as claimed in claim 1 wherein a class of the organic solvent is at least one of carboxylic acid, carboxylic acid/alcohol, carboxylic acid/aldehyde, acyclic carbonate, alcohol, aromatic ether, bicyclic ketone, cyclic carbonate, ester, ester/alcohol, ester/ketone, ether, fluorinated alcohol, furan, ketone, lactone, nitrile, polyol, sulfoxide, and water.

3. A process as claimed in claim 1 or 2 wherein the organic solvent comprises at least one of acetic acid, lactic acid, formic acid, dimethyl carbonate, 1 -butanol, 2-propanol, ethanol, methanol, t-butanol, anisole, cyrene, propylene carbonate, ethyl acetate, methyl acetate, methyl pivalate, n-butyl acetate, t-butyl acetate, ethyl lactate, butyl levulinate, 2-methyltetrahydrofuran (2-MeTHF), 2,2,5,5-tetramethyloxolane (TMO), hexafluoroisopropanol (HFIPA), 2,5-dimethylfuran, 2-methylfuran, 2-butanone, acetone, cyclopentanone, gamma-valerolactone, acetonitrile, glycerol, dimethyl sulfoxide (DMSO), and water.

4. A process as claimed in any of claims 1 to 3 wherein the organic solvent comprises a single organic solvent compound. A process as claimed in any of claims 1 to 3 wherein the organic solvent comprises a mixture of two or more organic solvent compounds. A process as claimed in any of claims 1 to 5 wherein the mixed waste stream comprises one or more materials to be recycled and one or more plastic additives. A process as claimed in claim 6 wherein the material to be recycled comprises at least one of polyethylene terephthalate (PET), high density polyethylene (HDPE), low density polyethylene (LDPE), polypropylene (PP), polyvinyl chloride (PVC), polyvinylidene dichloride (PVDC), polychlorotrifluoroethylene (PCTFE), acrylonitrile butadiene styrene (ABS), polyamide (PA), polystyrene (PS), polylactic acid (PLA), melamine, styrene butadiene rubber (SBR), natural rubber, nitrile butadiene rubber (NBR), cardboard (paper), ethylene-vinyl acetate (EVA), and aluminum foil. A process as claimed in claim 6 or 7 wherein upon contact of the mixed waste stream with the one or more organic solvents, the material to be recycled is dissolved by the one or more organic solvents, or the material to be recycled is swollen by the one or more organic solvents, or the material to be recycled has no interaction with the one or more organic solvents to at least partially separate the one or more components in the mixed waste stream. A process as claimed in any of claims 6 to 8 wherein the plastic additive comprises at least one of a stabilising agent, compatibilizer, antioxidant, antistatic agent, flame retardant, lubricant, plasticiser, antimicrobial agent, colouring agent, impact modifier, filler, reinforcement, blowing agent, fragrance, coupling agent, and residual catalyst from production. A process as claimed in any of claims 6 to 9 wherein upon contact of the mixed waste stream with the one or more organic solvents, the plastic additive is dissolved in the one or more organic solvents to at least partially separate the one or more components in the mixed waste stream. A process as claimed in any of claims 1 to 10 wherein the process comprises the step of receiving user input data on the type of the mixed waste stream. A process as claimed in any of claims 1 to 11 wherein the process comprises the step of determining an optimum amount of each of the one or more optimum organic solvents based on the type of the mixed waste stream. A process as claimed in any of claims 1 to 12 wherein the process comprises the steps of: identifying molecular solubility parameter data of the mixed waste stream, and identifying molecular solubility parameter data of a set of candidate organic solvents, wherein the one or more optimum organic solvents are determined based on the molecular solubility parameter data of the mixed waste stream and the molecular solubility parameter data of the set of candidate organic solvents. A process as claimed in claim 13 wherein the process comprises the steps of: generating a computational model representation of the mixed waste stream and the set of candidate organic solvents in a vector space based on the molecular solubility parameter data, and determining a vector distance between the representation of the mixed waste stream and the representation of each candidate organic solvent in the set of candidate organic solvents, wherein the one or more optimum organic solvents and the optimum amount of each of the one or more optimum organic solvents are determined based on the vector distances. A process as claimed in claim 13 or 14 wherein the molecular solubility parameter data comprises at least one of dispersion- forces data, polarity data, and hydrogenbonding data. A process as claimed in any of claims 1 to 15 wherein the process comprises the steps of: controlling reception of the mixed waste stream into a reaction vessel, and controlling passage of the one or more organic solvents from one or more holding vessels into the reaction vessel to contact the mixed waste stream. A process as claimed in claim 16 wherein the process comprises the step of controlling the amount of each of the one or more organic solvents passed from the one or more holding vessels into the reaction vessel. A process as claimed in claim 16 or 17 wherein the process comprises the step of maintaining the mixed waste stream and the one or more organic solvents in the reaction vessel under defined reaction conditions for a defined reaction time to at least partially separate the one or more components in the mixed waste stream. A process as claimed in any of claims 16 to 18 wherein the process comprises the step of engaging one or more mechanical elements with the mixed waste stream in the reaction vessel to at least partially separate the one or more components in the mixed waste stream. A process as claimed in any of claims 16 to 19 wherein the process comprises the step of controlling passage of the one or more organic solvents from the reaction vessel with at least some of the one or more plastic additives dissolved in the one or more organic solvents. A computer-implemented process as claimed in any of claims 1 to 20. A system for at least partially separating components of a mixed waste stream, the system comprising: a reaction vessel for receiving a mixed waste stream, an interface to obtain information on a type of the mixed waste stream, an optimiser to determine one or more optimum organic solvents based on the type of the mixed waste stream, and one or more holding vessels for the one or more optimum organic solvents, the one or more holding vessels being connected in communication with the reaction vessel to pass the one or more optimum organic solvents into the reaction vessel to contact the mixed waste stream to at least partially separate one or more components in the mixed waste stream. A system as claimed in claim 22 wherein the interface is configured to receive user input data on the type of the mixed waste stream. A system as claimed in claim 22 or 23 wherein the optimiser is configured to determine an optimum amount of each of the one or more optimum organic solvents based on the type of the mixed waste stream. A system as claimed in any of claims 22 to 24 wherein the optimiser is configured to: identify molecular solubility parameter data of a mixed waste stream, identify molecular solubility parameter data of a set of candidate organic solvents, and determine the one or more optimum organic solvents based on the molecular solubility parameter data of the mixed waste stream and the molecular solubility parameter data of the set of candidate organic solvents. A system as claimed in claim 25 wherein the optimiser is configured to: generate a computational model representation of a mixed waste stream and a set of candidate organic solvents in a vector space based on the molecular solubility parameter data, determine a vector distance between the representation of the mixed waste stream and the representation of each candidate organic solvent in the set of candidate organic solvents, and determine the one or more optimum organic solvents and the optimum amount of each of the one or more optimum organic solvents based on the vector distances. A system as claimed in any of claims 22 to 26 wherein the system comprises a controller to control the amount of each of the one or more organic solvents passed from the one or more holding vessels into the reaction vessel. A system as claimed in claim 27 wherein the controller is configured to control passage of the one or more organic solvents from the reaction vessel with one or more plastic additives dissolved in the one or more organic solvents. A system as claimed in any of claims 22 to 28 wherein the system comprises one or more mechanical elements to engage with a mixed waste stream in the reaction vessel to at least partially separate the one or more components in the mixed waste stream. A system as claimed in claim 29 wherein the mechanical element comprises at least one of a screw element and a filter element. A data processing system for at least partially separating components of a mixed waste stream, the system comprising a processor configured to perform the process as claimed in any of claims 1 to 21 . A computer program product comprising instructions capable of causing a computer system to perform the process as claimed in any of claims 1 to 21 when the computer program product is executed on the computer system.