The present invention relates to a method of processing waste fluorinated products,

Fluorinated products are used in a number of industries, with the vast majority of fluorine volumes world wide being found in treatments for fabrics such as clothing and carpets and are used to prevent staining and aid cleaning. Fluorinated products are also used in fire extinguishing foams, aerosol propellants and refrigerants for example. In particular, perfluorooctane sulfonate (PFSO) are used in the production of carpets; leather/apparel; textiles/upholstery; paper and packaging; coatings and coating additives; industrial and household cleaning products; and pesticides and insecticides.

Whilst there have been moves to reduce the use of fluorine based compound in patents, they are still widely used in certain industries, such as metal plating; fire fighting foams, the photographic industry, the use in semiconductors and in photolithography; and use in hydraulic fluids for the aviation industry. For fire fighting foams alone, it has been estimated that over 23.7 tonnes of PFSO-related substance is held by the UK alone.

In recent years, the dangers of the extensive use of such fluorinated products and indeed their subsequent safe disposal have been highlighted due to environmental

concerns. There is current legislation in Europe which prohibits the discharge of liquids containing Fluorinated products into ground water, namely under 'The Ground Water Directive 1998' (GWD). The directive was originally formulated in the late 70's. following concerns of high levels of Fluorine detected in the environment. These concerns result from the discovery that Fluorine was present in human blood, which was not the case 1958. The GWD has been fully adopted into UK law since 1998 and under this Directive materials that are classed as Persistent, or Bio-accumulative or Toxic (PBT) are classed as list I and the discharge of these materials into the environment is prohibited.

However, it is interesting to note that since the adoption of GWD 1998, there has no apparent prosecution in the UK under this legislation. An example of where this Directive may have been relevant is during fixed periodic foam fire extinguisher discharge. Under current guidelines for extinguisher servicing, each extinguisher must be discharged every five years for pressure testing under manufacturing and testing procedures detailed in BS5306 (EN3 and European Pressure Regulations). This waste foam is currently discharged to a main sewer and directed to water treatment. This practice is known by the Environment Agenc} (of UK) as a suitable wa> to deal with this waste, as there no acceptable alternative to dealing with this type of waste at this time. Prosecution under GWD 1998 would therefore be difficult, whilst the Fluorinated products still pose a danger to the environment and to health.

Many fire fighting foams use Fluorinated surfactants, as such surfactants are highly efficient at reducing the surface tension of finished foam, thus promoting the quick movement of a foam structure across the surface of Hydrocarbon and polar solvent fuels, quickening the time to extinguish fire. Due to the function and application of equipment used to extinguish fires such as foam monitors, delivery branches and portable fire extinguishers, foams by application are inevitably discharged directly into the environment and thereby directly into the environment.

Water containing foam solutions will not be permitted to be discharged to sewer without prior consent by the water operator with immediate effect. Fluorinated surfactants have a half life in ground water of 10 years and are expected to remain in soil substructure for 2000 years. Therefore, the recommended destruction of fluorinated foams is by incineration at temperatures greater than 1 100 ⁰ C.

Therefore, there is a requirement to provide a suitable method by which waste fluorinated products can be processed without discharging them straight into the environment that not only complies with current legislation, but is also addresses the environmental issues associated with disposal.

There are other foam types of fire extinguishers that are free of fluorinated

surfactants. Whilst these foams are a relatively new development in foam

technology designed to address the em ironmental issues associated with Perfluorinated foams, the volumes of these foams in the market place are

relatively low they do not match the performance levels of the Peril uorinated foam concentrates.

The extraction of fluorinated surfactants using activated carbon powder has been described {Pabon, M. et al, (2002) J. Fluorine Chem., 114, 149-156). However. in practice, the proteins present in the foaming material quickly block the active sites on the carbon upon which the fluorinated compound can bind, and therefore the process becomes inefficient after only a short period of time. Therefore, this process is not be suitable for high volume cleansing and requires frequent changing of the carbon powder.

JP62007489 discloses the addition of a polymer flocculant and polyaluminum chloride to a solution containing a protein foam fire extinguishing agent to perform flocculative sedimentation and filtering while adding hydrogen peroxide and ferrous sulfate to the filtrate to perform oxidizing treatment. Further, calcium carbonate is added to perform discoloration. The treated filtrate is treated by a centrifugal separator and activated carbon is added to the filtrate to adsorb a DOC component. The process described in this document has numerous steps with the addition of numerous chemicals and also requires the removal of the flocculated product from the solution. Such a method is suitable for processing protein based

fire extinguishing products.

An object of the present invention is to alleviate one or more of the problems associated with prior art processes for processing waste fluorinated products, and to provide a relatively inexpensive and scalable method of processing such waste.

In accordance with the present invention, there is provided a method of removing fluorinated material from a fluid comprising a fluorinated material and an oxidisible and/or enzymatically digestible substrate, the method comprising the steps of: a) introducing one or more oxidising agents and/or enzymes into the fluid; b) passing the fluid through an activated carbon matrix to remove at least part of the fluorinated material; and c) discharging the cleansed fluid from the activated carbon matrix.

The present invention therefore provides for a method of removing fluorinated material from a fluid in a relatively simple process that can be employed in a cost effective and scalable manner.

The method may further comprise the step of: d) disposing of the activated carbon matrix (when spent of otherwise). The spent activated carbon matrix may be disposed of by incineration. Preferably, incineration will be at a temperature that is deemed to be suitable for the destruction of fluorinated material such as temperatures in the region of 1100 ⁰ C. More preferably, the incineration takes place at temperatures in the region of 1000 - 1200 ⁰ C. After incineration,

the resultant ashes may be disposed of in accordance with usual procedures, for

example, being placed in land-fill sites due to the greatly reduced environmental

threat. The activated carbon matrix may comprise a plurality of activated carbon filters. The term "activated carbon ^* ' should be taken to mean carbon that has numerous acth e sites that are capable to binding to and retaining atoms such as fluorine atoms. Commonly, activated carbon is a charcoal derived material and a product similar to Acticarbone® may be employed. It will also be apparent to one skilled in the art that the particulate size of the carbon may be important in optimising the present method and the larger the surface area will result in a more efficient method. Carbon particulate contains levels of 'fines', and it is preferable that these fines are removed from the filter to ensure the reliability and efficiency of the filtration process is maintained. Fines can be removed with a sand filter following the filtration process if required. The carbon will preferably have a pore size of 18A or more. More preferably, the carbon will have a pore size within the range of 30-lGθA. It is also preferred that the density of the carbon is in the range of 0.18 G/ml (±0.04) and may also have a ash content of approximately 3.5% (±10%). The fluorinated material may be any material containing fluorine atoms, including perfluorinated material.

Preferably, the fluid is a liquid. Alternativeh . the fluid may be gaseous mixture and the process used to remcve the fluorinated compounds contained from the mixture. Should the fluid be a liquid, it may be a solution containing a fluorinated

product. The solution ma} be an aqueous solution and the fluorinated product may be mixed with water prior to passing it through the activated carbon matrix and the addition of oxidising agents and'or enzymes may be a the same time as

the addition of water or after. Preferably . the solution is a premix of tap water or

sea water mixed with the fluorinated material in a quantity of 98-50% water to 2- 50% fluorinated material. However, it will be apparent to one skilled in the art that the exact quantity will be dependent upon the fluorinated product and/or its concentration. For example, a premix of tap water or sea water mixed with a fire extinguishing foam concentrate, will usually be effecti\ely processed at a concentration of 6% (94 parts water 6 parts foam concentrate).

Pre-treatment of the fluid may also be performed with an anti-foaming agent. This will be particularly applicable should the fluorinated material be a foam forming material such as fire extinguishing foam. At least part of the foam forming material may comprise the oxidisable and/or enzymatically digestible substrate. The fluorinated material may be derived from fire extinguishers and may further be a foam fire extinguisher product. The fire extinguisher product may be selected from one or more of the following: Aqueous Film Forming Foam, Alcohol Resistant Aqueous Film Forming Foam, Protein Foam, Alcohol Resistant Protein Foam. Fluoroprotein Foam, Film Forming Fluoroprotein, Alcohol Resistant Film Forming Fluoroprotein and Agent Producing polymeric proactive precipitate (A4P). The fire extinguishing product may also contain a vapour suppressing agent.

It will also be apparent that other extinguishing products may also be used in

accordance with the present in\ ention. in addition to a number of other products and materials. For example, the method may also be employed to process other types of waste material incorporating fluorinated products, such as those from

other industries including (but not limited to) the production of carpets; leather/apparel; textiles/upholstery; paper and packaging; coatings and coating additives; industrial and household cleaning products; pesticides and insecticides, metal plating; the photographic industry, semiconductors, photolithography and hydraulic (and other) fluids for the aviation industry.

Preferably, the oxidising agent at least partially oxidises polymers in the fluid. The term "polymer" is intended to include a range of molecules built up from a series of smaller monomers and includes plastics materials in addition to proteins, polysaccharides, carbohydrates and oils etc. The use of the oxidising agent prevents the activated carbon form becoming inefficient as such polymers, such as polysaccharides, Xanthan gum. Protein and anti freezing agents blind the active sites (and indeed pores/openings) on the carbon surface that capture the Fluorine atom. The method must therefore allow for the processing of all types of fluorinated fluids, including foam solutions. For example, the protein molecule found in protein based foams will "'blind" the carbon filter material and render it ineffective. This is also the case with Xanthan gum used in alcohol resistant products and Gl}gols used for freeze protection. The oxidation of the foam solution breaks down these chemically stable structures, preventing them from becoming a problem with respect of the carbon. The majority of these polymers do not pose a substantial health or em ironmental threat and can be discharged for further purification and ^/ or discharged into the watercourse. A number of different

oxidising agents ma} be used in accordance with the present invention and these will be apparent to one skilled in the art. Preferably, the oxidising agent is

selected from or is mixture of one or more of the following agents: hydrogen peroxide and sodium metaperiodate. Additional buffers may also be employed to assist the action of the oxidising agent and/or the enzyme. The use of acidic or basic compositions can also be employed so as to adjust the fluid to the optimum pH of the fluid.

Should an enzyme be used in accordance with the present invention, it will preferably at least partially digest the polymers in the fluid. A range of enzymes may be employed, such the use of proteases for the digestion of proteins etc. The enzyme used will depend largely on the substrate upon which it has to act and therefore any enzyme could potentially be utilised.

The activated carbon matrix may be charged/conditioned with an aqueous solution prior to the actuation of the passage of the fluid. Therefore, all the spaces between adjacent particles of carbon will be saturated completely with fluid so that the maximum efficiency of the activated carbon can take place and the maximum surface area is available to absorb and retain fluorine material. Having the carbon matrix saturated also helps fluorine atoms diffusing throughout the fluid more efficiently. It is therefore preferable, that the process pre-charges the carbon matrix and introduces, in a continuous manner, an aqueous solution prior

to the addition of the solution containing the fluorinated material. Preferably, the activated carbon matrix is charged with water and thereby removing air from the

matrix, as the trapped air within the carbon matrix will also adversely affect the efficiency of the activated carbon in extracting the fluorinated compounds.

- J O -

The carbon matrix may comprise one or more main filters and one or more polishing filters. The provision of at least two filters allows the fluid to first pass through a main filter to remove a substantial part of the fluorinated material and then to pass through a polishing filter to remo\e the remaining fluorinated material. Additionally, when one filter becomes saturated with fluorinated material, the fluid may be passed through a new (or different) filter. Therefore, when a filter has become spent, the fluid can be passed through a fresh (or cleaned) filter. The same polishing filter may be used when a fresh filter has been implemented, or alternatively a new polishing filter be used. The fluid may also be cycled within the activated carbon matrix and the fluid may be cycled through a number of filters. Preferably, the fluid is forced through the activated carbon matrix against gravity and/or pressure. In order to achieve this, the fluid may simph be pumped from a lower part of the matrix to an upper part of the matrix. The filters may comprise interchangeable cartridges, such that new cartridges can be used to replenish the carbon matrix and the spend carbon can easily disposed of.

It will be apparent to one skilled in the art that the number and size of the filters will depend on the \olumes of foam solution to be filtered over a given period.

The filters ma\ be in the configuration of towers or elongated tubes containing the actuated carbon. The fluid may be passed through the filters in consistent batch \ olumes (thus ensures thai the oxidation process is complete prior to the solution entering the carbon towers)or on a continuous basis.

In accordance "with another aspect of the present invention, there is provided a method of removing fluorinated material from a liquid comprising fluorinated material and polymers, the method comprising the steps of: a)introducing one or more oxidising agents and/or enzymes into the liquid: b) passing the liquid through an activated carbon matrix to remove at least part of the fluorinated material; and c) discharging the cleansed liquid from the activated carbon matrix.

In accordance with yet a further aspect of the present invention, there is provided an apparatus for the removal of fluorinated material from a fluid comprising one or more activated carbon matrices having an inlet and an outlet and a means for introducing one or more oxidising agents and/or enzymes into the fluid within or before the inlet.

The apparatus may further comprise a means for introducing an anti-foaming agent into the fluid within or before the inlet. Such a means may be simply a tube or similar device that is capable of dispensing a quantity of agent and'or a quantity of oxidising agents and/ or enzymes into the fluid. A mixing means may also be employed to ensure that the agents are thoroughly mixed within the fluid and such a mixing may be undertaken in a separate vessel prior to the introduction of the fluid into the apparatus.

Preferabl) . the activated carbon matrix comprises an interchangeable cartridge. Such a cartridge may be modular for inserting into the apparatus and therefore

provide a quick and simple method of replacing spent carbon. Indeed, the cartridges will allow the apparatus to be serviced regularly and for relatively unskilled persons to operate the apparatus. Furthermore, the cartridges be refilled or incinerated depending on the cost of providing new cartridges. The apparatus may be produced in a range of sizes so as to provide a relatively small apparatus so as to be mobile or to process a small amount of fluorinated material. Alternatively, the apparatus may be on a large scale so as process large amounts of fluorinated products. The apparatus may additionally comprise one or more reservoirs for holding fluid prior to or after being passed through the matrix.

The apparatus may additionally comprise at least one main filter for removing a substantial part of the fluorinated material and at least one polishing filter to remove the remaining fluorinated material. Therefore, the inlet will be linked to the main filter, which will in turn, be linked to the polishing filter before allowing the cleansed fluid to pass from the outlet. It will also be apparent that the apparatus pro\ide for the continuous throughput of waste fluorinated material by having a number of cartridges which come on-line or go off-line depending upon whether the filter is spent or not. The switching of cartridges may be

determined b\ the length of lime that the apparatus has been in operation, the volume of fluid that has passed through the filters and/or the fluorine atom content of the fluid from the outlet and/or held within the filter(s).

In order to assist in the flow of the fluid throughout the apparatus, it may further comprise one or more pumps so as to pass the fluid through the activated carbon matrix from the inlet to the outlet. Preferably, the pump is a peristaltic pump. The apparatus may further comprise a sensing means for sensing when a filter is substantially saturated with fiuorinaled material. On method of determining the saturation of a given filter may be to assess the surface tension of the water as the tension can provide and indication of saturation of fluorine atoms. The apparatus may divert the passage of fluid to a second filter when the sensing means has sensed that a filter is substantially saturated with fluorinated material. A central processing unit may be employed for controlling the passage of the fluid through the apparatus.

The apparatus may be used to undertake the method of removing fluorinated material from a fluid as described herein above.

The present invention will now be more particularly described by way of example only and with reference to the following figures.

Figure 1 is a perspective exploded cut away view of an apparatus in accordance with the present indention;

Figure 2a is a perspective view of the apparatus as shown in Figure 1 within a

holding cage:

Figure 2b is a cross-sectional view of the apparatus as shown in Figure 2a, along the dissection line X-X;

Figure 3 shows a cross-sectional view of one of the towers which is incorporated into the apparatus of the present invention.

Figure 4 is a schematic diagram of how the apparatus in accordance with the present invention will be employed.

With reference to Figure 1 , there is provided an apparatus for removing fluorinated material from a liquid solution, the apparatus having three towers 2, 10, 16 containing activated carbon in a central region 4. An inlet 6 is capable of receiving fluorinated material in a solution form and is connected to a reservoir 8 which in turn is connected to the first tower 10 which has three chambers 12, each of which containing activated carbon and being separated by means of a gauze 14. Both towers 16 and 2 can be connected to the upper reservoir 18 which holds the cleansed liquid and allows it to be removed via the outlet 20. Arrows 22 show the overall flow of the fluid throughout the apparatus.

With reference to Figure 2a and 2b, there is provided a device as shown in Figure 1 which is held within a framework 40 consisting of four upwardh extending

members 42. 44. 46 which are joined together at the base 48 and allow for the de\ ice to be easily dismantled and assembled when appropriate means of lowering components into the framework. A door 50 permits access to the towers

2. 10, 16 which contain the activated carbon. The door 50 therefore allows the towers to be easily changed as and when appropriate. Further doors (not shown) can also be provided so as to allow access to the towers. X-X shows a cross sectional view of the apparatus in Figure 2b which also shows arrows radiating from the various towers 2, 10. 16 and represents the flow of liquid throughout the towers.

With reference to Figure 3. there is provided a tower 60 having three chambers 62. 64, 66, each of which contains activated carbon particles. Each chamber is separated by a filter membrane which can be a metal gauze or filter material which acts to allow fluid flow therethrough, but prevents the carbon particles from moving between chambers. A reservoir 70 is filled with the fluid containing fluorinated material and the reservoir is filled via the inlet 72. The flow of the fluid is indicated with arrows in Figure 3 and shows the movement of the fluid through successive chambers 66. 64, 62 and finally passing out of the outlet 74.

Referring to Figure 4, the schematic diagram illustrates the process implemented b\ the apparatus which includes a holding tank 88 within which may be placed a pre-treatment solution 86 before the fluid containing the waste fluorinated material in reservoir 88 will be pumped into one of the three towers 80, 82. 84 (containing the activated carbon). After the fluid has passed through the at least one of the towers, it can then pass straight to a cleansed fluid reser\oir 92. or farther processed in a processing chamber 90 should the fluid require further

treatment. Alternatively, it may pass to a polishing chamber 82. prior to being discharged from the apparatus.

In use (and referring to all the Figures) waste fluid containing fluorinated material may be mixed or diluted with water in an appropriate quantity and agents such as oxidation agents, enzymes or anti-foaming agents and introduced in to the reservoir 8, 88 by means of a pre-treatment 86. Such mixing may take place within a pre-treatment tank or similar apparatus. Whilst the exact agents used will be dictated by the waste fluorinated fluid material in the example of waste material from a fire extinguisher, an oxidising agent such as hydrogen peroxide may be used in addition to, or separately from an enzyme such a protease (to a digest a protein content of the foam) in addition to an anti-foaming agent. The fluid from the reservoir 8, 88 is then pumped against gravity up into a first tower 10. 80 and the liquid will pass over the activated carbon held within chambers 66« 64. 62. The fluid is then passed into a second chamber 16, 82 termed a '"polishing tower" and this tower is used so as to remove the remaining fluorinated material from the fluid prior to the fluid being disposed of. Should the first tower 10, 80 become saturated with fluorinated material and therefore ineffective, the fluid can pass straight to a third tower 2. 84 and then through the polishing tower 16, 82. After the polishing tower, the fluid can then go into a further holding tank 90

where the fluid may be further processed or the fluid can simph then pass to a holding tank 92 for disposal into the water course.

The apparatus has a modular format and therefore, in reservoirs 8, 18 (88, 90,92) can be removed by simply lifting the components from the cage 40 which holds the apparatus together. A number of releasable connectors may also be providing with the apparatus so that the reservoirs and/or the towers can be removed and replaced quickly and easily without the spillage of fluorinated fluid. The towers can be replaced on a regular basis and/or be replaced when the carbon is saturated and the towers can either have the carbon removed and replaced, or simply incinerated. Reservoirs 8, 18, 88,90 and 92 can also be removed and cleaned where appropriate.

The apparatus may operate automatically whereby it is controlled by a central processing unit or computer which can monitor the through flow of the fluid throughout the apparatus and indeed sense when a tower has become saturated with fluorinated material and therefore shift the flow of fluid from the first tower 12, 80 to the third tower 2, 84 before it enters the polishing tower 16, 82. Of course, the switching of flow of the fluid can be automatically actuated through the control of various pumps located within the apparatus.

The apparatus ma}' also be a number of sizes and dimensions and include many more towers than three, although it is preferable that there are at least two towers of activated carbon and an additional polishing tower.

The flow rate of the liquid through the apparatus will be directly related to the

diameter and height of the towers. The volume of carbon filter material in each

tower will also determine how much solution can be passed through the carbon before saturation of the carbon by fluorinated surfactants is achieved. At the point of saturation, the carbon is no longer effective in the process and must be changed.

The design of the size of tower is such that it will allow several batches of solution to be passed through one tower before saturation of the carbon takes place. However, the solution will pass through the second tower as part of the filtration process. This tower is known as the 'Polishing Tower'. The design of each of the towers allows for a 10 to 20% margin of error in the saturation point of the carbon contained in each tower. This is to ensure that the set volume of solution will not saturate the carbon in the tower more than 90% of it's total saturation point. However, the 'Polishing Tower' is in process to ensure that should this margin of error be breached, the fluoro surfactants can not by pass through the apparatus without being removed.

Following the passing of the solution through the 'Polishing Filter', the solution can then be held in a storage vessel for analysis. At this point fluorosurfactants should not be detecable. Should the solution be found to contain more than, for example, 10 ppm of fluorosurfactants. then the 'Primary Tower' has reached 100% saturation of carbon. The solution would then be placed back into the filtration process.

During use of the third (and subsequent towers if used) tower in the process, the first tower can be isolated and the carbon changed, the tower can be conditioned once again and made ready for use within the process when the third tower is 'spent'. The carbon within the 'Polishing Tower' will be changed periodically and only when the filtration process is not in use. The design of the tower size will allow ^r for several changes of carbon in tower one and three before the 'Polishing Tower' will need a change of carbon. Other than this basic design, the number of carbon tow ⁷ ers is not limited other than by available space.

The saturated carbon can then be sent for incineration at a temperature greater than 1100 ⁰ C. The Perfluorinated free foam solution can be safely discharged to the main sewer and onto water treatment. Preferably, non of the chemicals used in the oxidation process will have any detrimental impact on sewer treatment.

A compact filtration unit as described, combining the total process, relatively small and easy to operate. Alternatively or in addition, one large fixed process site combining the total process and managed by single operator for example.

An example of the apparatus may be one with a construction design that can be self-contained and manufactured from a plastics material. The dimensions of the apparatus being: Diameter of carbon cage approx 200mm; Height of carbon cage

approx 350mm; main diameter approx 800mm; Height of main body approx 2 metres. The pump flow rate being between 1 and 3 litres per minute (Peristaltic type). A control panel is also located on the apparatus so as to control the

apparatus and alter parameters/notify the user when towers are saturated etc. The pumps and values can also be operated by electrical power and may be motor driven or hydraulic.