GB2391785A

GB2391785A - Treatment of chemical and biological hazards using UV light an a titanium oxide catalyst

Info

Publication number: GB2391785A
Application number: GB0318364A
Authority: GB
Inventors: Iain Fraser Jarvies; Steve Barfield
Original assignee: Albagaia Ltd
Current assignee: Albagaia Ltd
Priority date: 2002-08-07
Filing date: 2003-08-06
Publication date: 2004-02-11
Also published as: GB0318364D0; GB0218314D0; WO2004014437A1; US7491339B2; ATE408424T1; AU2003249077A1; EP1572252A1; DE60323671D1; EP1572252B1; JP2005534490A; US20050269272A1

Abstract

The present invention relates to a method for the deactivation and / or destruction of hazardous materials such as chemical or biological agents. The invention further relates to apparatus for treating hazardous material and for decontaminating items that may have come into contact with it, the apparatus comprising a treatment vessel or chamber and a light source capable of irradiating a catalyst within the treatment vessel or chamber with a predetermined wavelength of light. The vessel is accessible by the user and the light source is an ultra-violet lamp for sterilising biological material. Additionally, a titanium oxide catalyst may also be used. The hazardous materials are placed in trays in which a turbulent flow, within an aqueous carrier is induced.

Description

1 Apparatus and method for treatment of chemical and 2 biological hazards

4 The present invention relates to an apparatus for the 5 treatment of hazardous materials specifically priors, 6 chemical and biological agents. The invention further 7 relates to a method for using such an apparatus.

9 The risks associated with contamination caused by 10 chemical and biological agents of various kinds are 11 well known. Medical equipment and surgical instruments 12 are required to be sterilized to eliminate a growing 13 range of infectious agents including more recently 14 prions implicated in new variant Creusfeld Jacob 15 Disease (nvCJD). Proteins exhibit huge variation in 16 structure. However, they are formed in similar ways 17 and thus display certain structural elements and 18 characteristics that are common. The primary structure

! 1 of proteins is determined by the amino acid sequence 2 and pendant side groups. The amino acid chains are 3 then folded to form various secondary structures 4 designated as a-helices or p-sheets. Secondary 5 structure is determined by the folding of the amino 6 acid chains and interactions between the various side 7 groups. Further associations may also form, depending 8 on the protein's environment. For example different g hydrophilic and hydrophobic groups or areas within the 10 protein molecule are sensitive to the medium in which ll the molecule may be suspended. The prion protein plays 12 an essential role in the pathogenesis of a group of 13 sporadic, genetically determined and infectious fatal 14 degenerative diseases, referred to as prion diseases, 15 or transmissible encephalopathys (TSE's), affecting the 16 central nervous system of humans and other mammals.

17 The cellular prion protein is encoded with a single 18 copy gene, highly conserved across mammalian species.

19 In prion diseases this protein undergoes conformational 20 changes involving a shift from a-helix to p-sheet 21 structure. The structures of the proteins, both native 22 and rogue, have been extensively investigated. The one 23 of most interest and immediate impact to humans is the 24 protein associated with nvCJD. What is unusual about 25 the protein that is associated with TSEs is the extreme 26 robustness it exhibits. This is thought to be due its 27 p-sheet structure. Prions are known to survive 28 temperatures in excess of 300 C. Such proteins thus

( 1 represent present particular problems in terms of their 2 transmission and destruction. The nvCJD prion is known 3 to have a high affinity for stainless steel and other 4 metals posing significant difficulties for the 5 sterilization of medical equipment, such as surgical 6 instruments. At the same time, considering hazards 7 unrelated to the medical field, chemical and biological

8 agents, such as those used as weapon materials, pose 9 significant handling and disposal risks.

11 For the purposes of the present application, the term 12 "hazardous material" means any organic material that 13 may be inimical to human well being and as such may be 14 classed as a chemical or biological hazard. "Hazardous IS material" includes, but is not restricted to, viral 16 material, bacterial material, priors, proteins, lipids, 17 chemical and biological agents / material with 18 associated organophosphate bases, organic waste or by 19 products associated with pharmaceutical processes and 20 blood products, and further includes all of said agents 21 in isolation and when found within, on the surface of 22 or bonded to other material, instruments or equipment.

23 The term "target material" is used throughout in 24 reference to a "hazardous material" which is to be 25 treated according to the method of the invention.

27 The term "treatment" is used in its broadest form and 28 encompasses the deactivation and destruction of 29 hazardous material. Relatively minor modifications to

( 1 the structure or conformation of a particular agent may 2 be sufficient to render it inactive without the need 3 for the agent to be destroyed or decomposed into 4 constituent elements.

6 While some methods for treating such agents are known, 7 these typically involve the use of reagents which are 8 themselves difficult to handle and which have 9 associated safety issues. Fluorine and ozone for 10 example may be effective in catalyzing such processes, 11 but create significant handling problems and are not 12 suited to use in an open bath apparatus. Furthermore 13 some prior art processes are required to be carried out

14 at very high temperatures and / or pressures. The 15 apparatus used in such processes is necessarily complex 16 and expensive in light of the associated handling 17 difficulties.

19 There remains therefore a need for a method for the 20 deactivation or destruction of priors, chemical and 21 biological agents, which is effective, efficient and 22 broadly applicable. There is a particular need for an 23 apparatus and a treatment method that can be used to 24 sterilize or decontaminate equipment and instruments 25 that may have come into contact with hazardous 26 material. The present invention as set out below 27 provides such an apparatus and a method for its use.

( 1 Accordingly, in a first aspect the present invention 2 provides apparatus for treating hazardous material and 3 for decontaminating items that may have come into 4 contact with such material. In its broadest form such 5 apparatus comprises an operator accessible treatment 6 vessel or chamber and a light source capable of 7 irradiating a catalyst within the treatment vessel or 8 chamber with a predetermined wavelength.

10 A first embodiment of the invention provides an 11 apparatus, for batch treatment of hazardous material, 12 comprising a treatment vessel for holding material to 13 be treated; a light source for irradiating the contents 14 of the treatment vessel; circulation or agitation means 15 and progress and / or by-product monitoring means. The 16 treatment vessel may comprise a 'glove box' type lid 17 facilitating manipulation of the bath contents by an 18 operator. An automatic light source cut-off may be 19 incorporated in order to enhance operator safety.

21 A second embodiment provides an apparatus comprising a 22 treatment vessel having one or more decontamination 23 trays for holding hazardous material or items to be 24 treated, a light source for irradiating the contents of 25 the treatment vessel, medium distribution means for 26 circulating a carrier medium within and / or through 27 the apparatus and by-product monitoring means.

1 A third embodiment provides an apparatus comprising a 2 holding tank for holding a carrier medium; a catalyst 3 hopper for holding a catalyst; a mixing vessel for 4 mixing the carrier medium and the catalyst; one or more 5 treatment chambers each having a housing which contains 6 a plurality of treatment beds and a light source; and a 7 distribution header for controlling the flow of carrier 8 medium and catalyst into the treatment chambers.

9 Preferably, each treatment bed comprises means for 10 inducing turbulent flow within the carrier medium 11 flowing therein.

13 A second aspect of the present invention provides a 14 method for the deactivation and / or destruction of 15 hazardous material comprising the step of irradiating 16 the hazardous material in the presence of a catalyst 17 with light having a wavelength in the range of 310 nm 18 to 400 nm. The method of the invention causes 19 sufficient chemical modification of the hazardous 20 material so as to deactivate or destroy it.

22 Preferably, the catalyst is TiO2 in either rutile or 23 anatase form and preferably the method is carried out 24 at ambient temperature (of between about 15 to 35 C) 25 and pressure (of between about 1 to 5 bar).

27 The method may be carried out in any water based 28 carrier medium that is compatible with the target 29 material and catalyst. Preferably the carrier medium

( 1 is water. Judicious choice of treatment medium is! 2 required in order to ensure reliable and effective 3 treatment. In particular when considering the 4 treatment of objects or instruments contaminated with A 5 prions for example the physical characteristics of the 6 apparatus and method should facilitate a suitable -

7 reaction interface. This involves consideration of the 8 composition and viscosity of the carrier medium and the -

9 path-length of the apparatus such that the target 10 material, catalyst and photons from the light source 11 are brought together in a manner suitable to effect 12 treatment. It follows that a medium that is relatively 13 low in viscosity and has appropriate optical 14 characteristics (over the wavelength(s) of the light 15 source) is desirable. In other words, the viscosity 16 must be such as to allow the bringing together of the 17 target material and the catalyst and the configuration 18 of the apparatus and the optical characteristics of the 19 medium must allow sufficient transmission of light to 20 the target / catalyst reaction site.

21 = 22 Thus, the present invention provides for the treatment 23 hazardous material such as prions linked with human or 24 animal nvCJD in both a and forms and for treatment of 25 instruments and equipment that may have been 26 contaminated with said material. The method, and 27 apparatus for implementing it, are also applicable to 28 the destruction of chemical agent material, typically

( 1 organophosphate based systems, as typified by VX or 2 Sarin, but additionally blistering and choking agents 3 as typified by Mustard Gas and Tear Gas. Depending 4 upon the conditions employed, the invention provides I 5 for total destruction of some hazardous material by 6 breaking it down into its constituent parts, 7 principally carbon dioxide, nitrogen, water and 8 inorganic salts, or alternatively provides for 9 sufficient modification of target materials so as to 10 render them inactive. The invention can also 11 deactivate or destroy many other biohazards, viral and 12 bacteriological material, and many commonly 13 industrially produced organic materials. Furthermore, 14 the method of the invention can be employed to -

15 decontaminate materials, equipment, instruments and the 5 16 like which may have come into contact with hazardous -

17 material.

18 - 19 The method of the invention represents an efficient: 20 means of deactivating and / or destroying of hazardous 21 material under mild conditions on a batch basis. = 22 Further advantages of the invention are described 23 below.

25 The various aspects of the invention are described in 26 detail below with reference to the accompanying 27 drawings in which: -

( 1 Figure 1 shows a first embodiment of an apparatus 2 according to the invention; 3 Figure 2 shows a second embodiment of an apparatus 4 according to the invention; a 5 Figure 3 shows a third embodiment of an apparatus 6 according to the invention; and -

7 Figures 4 and 5 are more detailed views of the 8 treatment chamber of the embodiment shown in Figure 3. -

10 In the drawings similar reference numerals have been 11 used to designate components common to each of the 12 alternative embodiments.

14 In its broadest form the invention provides a 15 decontamination method for the treatment of hazardous 16 material comprising the step of irradiating the 17 hazardous material in the presence of a catalyst, with 18 light of a suitable wavelength, to deactivate or -

19 destroy the target material through photocatalytic 20 oxidative processes. In general terms, the apparatus 21 of the present invention comprises (i) a treatment = 22 chamber in which the catalyst and the target material e 23 may be irradiated with light of a suitable wavelength 24 (and energy) and (ii) a light source capable of 25 producing the desired wavelength. The light source 26 wavelength and intensity may be adjusted to optimise 27 the process depending upon the nature of the target 28 material and the choice of catalyst. A liquid carrier, 29 preferably a water based medium, is used to introduce

( 1 hazardous material into the treatment chamber for 2 irradiation.

4 Without being bound by theory, the invention is 5 considered to be the result of an interaction of light 6 energy (photons), the catalyst and water elements that 7 forms hydroxyl radicals which cleave sections of, or 8 links in, molecules of the target material ('primary 9 effects'). The action of W light contributes directly 10 to the breakdown of target materials through photolysis t 11 of molecules present. In conjunction with the t 12 formation of hydroxyl radicals hydrogen peroxide (H2O2) 13 is also produced. This oxidizing agent assists and 14 speeds the decontamination process cycle. The primary 15 effects of hydroxyl radicals allow secondary processes 16 (such as attack by H2O2) to act upon vulnerable parts of 17 the molecules. The ultimate result is the break down 18 of hazardous material into simple (safe) moieties, 19 formation of inorganic salts within the carrier medium i 20 and production of off-gases, such as CO2.: 22 The method of the invention employing highly reactive 23 hydroxyl radicals and H2O2 produced through irradiation 24 of a suitable catalyst can be utilized to oxidise prion 25 proteins decomposing them to NOx, CO2, water and various 26 inorganic salts. Attack on a prion protein molecule by 27 a hydroxyl radical causes selective breakage of 28 multiple bond linkages, thus permanently altering the 29 crucial relationship between amino acid units and

( 1 inducing changes to their proper attachment and 2 alignment to each other (and to associated components 3 such as carbohydrates and possibly lipids). This 4 effect changes the spatial configuration of the prion 5 protein impacting upon its ability to reproduce 6 properly. It is possible that even small alterations 7 in the protein composition and / or configuration are 8 sufficient to impede biological activity of a prion 9 molecule. Any alteration in the structural make-up and 10 configuration reduces the resistance of the prion to 11 further oxidative processes, such as attack by H2O2, 12 thus increasing the rate of complete oxidation of the 13 molecule.

15 Contact between the hydroxyl radical / hydrogen 16 peroxide production interface and the target material 17 on the equipment / instruments or the like, using the 18 water based carrier medium with the catalyst, is 19 maximized. This may be addressed by ensuring that the 20 catalyst within the water carrier is migrated to the 21 interface using suitable circulation or entraining 22 processes. Minimising the spatial offset in this 23 manner increases the effects of the short-lived 24 radicals produced upon irradiation. Spatial offset 25 distance is further aided through the use of small 26 catalytic particulate t3 - 5 microns).

i 1 Prior cleaning of gross material make take place within 2 the decontamination train, that minimises the volume of 3 material to be decontaminated, and improves throughput.

5 Increasing the intensity of irradiation and / or 6 increasing the surface area of catalyst irradiated can 7 increase radical production. Additional catalyst may 8 be introduced to speed the process and replace catalyst 9 extracted from the waste stream.

10 The catalyst may be any photosensitive material, which 11 allows, through illumination with light of a suitable 12 wavelength, a reaction with the associated hazardous 13 material to occur. Suitable catalyst materials include 14 for example Tick, TiO3, ZnO, CdS, CdSe, SnO2, WO3, Fe2O3 15 and Ta2Os. An example of a preferred catalyst is TiO2.

16 Irradiation of the catalyst produces active sites (on 17 what is in effect a semiconductor surface) causing 18 water absorbed to the surface to be oxidized. Highly 19 reactive hydroxyl radicals formed in this manner react 20 with (and ultimately decompose) the target material 21 present in the system.

23 The catalyst may be used in any form that provides 24 suitable contact with the target material. For 25 example, the catalyst may be dispersed in the carrier 26 medium or it may be coated onto or mixed with the 27 various materials to be decontaminated or destroyed. A 28 catalyst module such as a column or tower coated with

( 1 catalyst material may be employed. Alternatively, the 2 catalyst may be coated onto internal surfaces of the 3 apparatus, enhancing robustness and self-cleaning 4 capability. Recovery of the catalytic material for 5 reuse, increasing efficiency of the process, may be 6 provided for as described below.

8 While light in the range of 310 nm to 400 nm is 9 preferred, the wavelength of light employed may vary 10 depending upon the catalyst used, the medium used and 11 the nature of the target material. The wavelength to 12 be used may be selected based on the absorption 13 characteristics of the target material, thus increasing 14 efficiency. As photo-generated hydroxyl radicals are 15 the primary agents responsible for the decontamination 16 / destruction processes various parameters may be -

17 changed to optimize the effect upon any given target 18 material. The selected wavelength may be produced for 19 example using a standard mercury lamp in conjunction -

20 with a suitable filter.

22 The method of the invention degrades target materials 23 ultimately reducing them to simple reaction products 24 such as CO2. The evolution of CO2 or any other reaction 25 product can thus be used to monitor the degree and rate 26 of the process. Suitably off-gas production or target 27 material break down may be monitored using techniques 28 such as Raman spectroscopy, mass spectrometry, in vitro

( 1 tests or other known techniques appropriate to any 2 particular hazardous material.

4 Characteristics of the method of the invention are 5 detailed in Table 1, together with comparable data for 6 various prior art methods. The 'efficiency' values

7 indicate the rate and effectiveness of electron 8 transfer during the treatment process.

( Catalyst Efficiency Medium Output Temp Pressure Power (eV) toxicity ( C) (bar) ._. TiO2 3.34 Water Very low c36 <10 Low (present invention) Ag (II)* 1.98 Nitric Nigh 90 10 High l Ruthenium* 1.8 H2SO4 High 90 10 High Chlorination* 1.3 Water High 40 <10 Low: H202 2.00 Water Low <36 c10 Low 2 Table 1. Indicates prior art process; Hydrogen;

3 peroxide not a catalyst as such - included 4 for comparison purposes only.! 6 Prior art methods (other than those detailed in Table I

7 1) include hydrogenation and methods employing molten 8 metals or supercritical water. These additional 9 methods all pose significant hazards themselves due to 10 the operating conditions required in order to be 11 effective (for example, all three require temperatures 12 in excess of 600 C; and hydrogenation and 13 supercritical water methods operate at pressures of 14 about, or in excess of, 100 bar). Treatment with 15 fluorine, possibly the strongest oxidising agent known, 16 is also effective, but extremely difficult and 17 dangerous to handle.

1 The method of the invention provides an effective and 2 efficient process for the deactivation and / or 3 destruction of hazardous material, on batch or 4 continuous basis, while overcoming the shortcomings of 5 some prior art methods in terms of operational

6 requirements and characteristics. The present 7 invention facilitates decontamination treatments to be 8 carried out under ambient temperature and pressure 9 conditions through a method and apparatus which has 10 minimal moving parts, is easy to maintain and operate 11 and which is readily scalable.

( _ _ Class of Compound Examplen Alkanes Methane; pentane; heptane; ndodecane; cyclohexane, paraffin _ _: Haloalkanes mono-, di-, trim, and.

tetrachloromethane; dichloropropane I Pentachloroethane; di and tribromoethane; 1,2-dichloropropane Aliphatic Alcohols methanol; ethanol; n- and iso-propanol; butanol; penta-l, 4-diol - _ _ Aliphatic methanoic, ethanoic; Carboxylic Acids trichloroacetic; butyric; oxalic _ Alkenes propene; cyclohexene.

Haloalkenes di-, tri- and tetra-chloroethene;: hexafluoropropene Aromatics benzene; naphthalene, Tributyl Phosphate Haloaromatics chloro and bromobenzene;: chlorobenzenes; halophenols Phenols phenol; hydroquinone; catecol; resorcinol; cresol, nitrophenol Aromatic benzoic; phthalic; salicyclic Carboxylic Acids _ _ Polymers polyethylene; PVC.

Surfactants polyethylene glycol; p-nonyl phenyl I ether; sodium dodecyl benzene sulphonate; paraxon; malathion Herbicides methyl viologen; atrazine; simazine; bentazon Pesticides DDT; parathion; lindane, monocrotophos Dyes methylene blue; rhodamine B; methyl orange; fluorescein _ Explosives Trinitrotoluene Cyanotoxins Microcystins, Anatoxin-a Bacteria E.Coli., Serratia marcescens, _ Proteins Table 2

( 1 Table 2 lists compounds successfully destroyed using 2 the present invention. Tributyl phosphate, appearing 3 in the 'Aromatics' class, is a simulant for nerve 4 agents. I Material Concentration Wavelength Time Efficiency (%) (% v/v) (nary) (win) Methanol 0.1 385 +/- 10 20 gg.5 Paraffin 0.1 385 + / - 10 40 99.75 Benzene 0.1 380 + / - 10 60 99.9 6 Table 3.

8 Table 3 details a number of test materials and the 9 conditions under which they were treated. In each case 10 treatment was carried out at atmospheric pressure and 11 at room temperature. The treatment efficiency (which 12 in the case of the three test materials corresponds to 13 destruction of the compounds in question) was measured 14 using spectrophotometric techniques.

16 The specific embodiments of an apparatus according to 17 the invention described below may each be provided with 18 a circulation system, a catalyst feed mechanism, and a 19 catalyst recovery system. In addition there may be a! 20 flushing mechanism to remove excess free catalyst 21 deposits from the cleaned instruments or tools and 22 materials prior to final removal and drying. Larger 23 units having the same basic unit structure may be

( 1 complemented by material towers coated with the 2 catalyst through which the contaminated material in the 3 water-based matrix is allowed to percolate, thus 4 increasing exposure of the contaminants to the catalyst 5 and W sources.

7 Prior cleaning of gross material make take place within 8 the decontamination train, that minimizes the volume of g material to be decontaminated, and improves throughput.

11 A first embodiment of an apparatus according to the 12 invention is shown schematically in Figure 1. The 13 apparatus comprises a treatment chamber or bath (1), a 14 light source (2), a circulation pump (3), an off-gas 15 monitor / treatment unit (8), a catalyst recovery 16 system (4) and a holding tank (5). A catalyst hopper 17 (6) and a medium storage unit (7) for storing the I 18 catalyst and carrier medium prior to use are also 19 provided. This first embodiment has been designed for 20 small quantity throughput of, for example, surgical 21 instruments for decontamination or for destruction of 22 small quantities of target material. Manual 23 manipulation of items in the treatment chamber may be! 24 facilitated through use of a glove-box type lid (9).

25 This apparatus is designed for operation by medical 26 staff in for example medical or dental practices.

28 Catalyst material and carrier medium are introduced 29 into the holding tank (5), from the catalyst hopper (6)

( 1 and the medium storage unit (7) respectively, and from 2 there into the treatment chamber (1). The catalyst is 3 typically suspended in the carrier medium and suitable 4 stirring means may be provided in order to ensure that 5 suspension is maintained and that the suspension 6 circulates within the chamber (1). The contaminated 7 equipment or target material (not shown) is placed in 8 to the bath; the lid closed and interlocks (not shown) engaged before the process commences. In order to 10 maintain the catalyst in suspension within the carrier 11 medium during the process, the medium is circulated 12 through the system by using suitable means. This 13 facilitates maximum irradiation of the catalyst 14 simultaneously allowing the catalyst particles to 15 contact the interface with the target material. A 16 circulating pump (3) is used for the removal of 17 catalyst via the catalyst recovery system (4) at the I 18 end of the process run. The catalyst recovery system 19 (4), typically takes the form of a cyclone separator.

20 The level of catalyst in the system is monitored via 21 the process controller (not shown) and adjusted to the 22 required level. The carrier medium is circulated 23 within the bath (1) during the! 24 decontamination/destruction process and may be replaced 25 or replenished from the medium storage unit (7) or via 26 the catalyst recovery system (4). The process 27 controller (not shown) is used to monitor the overall 28 process, including monitoring off-gas production within 29 the off-gas monitor/treatment system (8). The off-gas

( 1 monitoring system (8) provides the means by which the 2 primary process status is monitored. The destruction 3 of organic elements produces CO2, when no further CO2 production is detected the treatment process may be 5 regarded as complete. The residual CO2 given off is 6 collected by use of an active charcoal filter fitted 7 into the off-gas system (8. Sampling can be 8 facilitated in order to allow for conformity in vitro 9 testing, spectroscopic analysis or the like to take 10 place. Once completion of the process has been 11 confirmed the used carrier medium can be disposed of in 12 a recognized manner and the apparatus may be flushed 13 with fresh medium. The flushing process enables all the 14 areas within the apparatus that may have been 15 contaminated by target material to be cleaned, although 16 the system is inherently selfdecontaminating. The 17 carrier medium within treatment chamber (1) is then I 18 topped-up prior to next usage and the medium in the 19 holding tank (7) replaced. While the method of the 20 invention may generally be carried out at, or close to, 21 atmospheric pressure, materials may be passed through 22 the apparatus under higher pressure particularly during 23 catalyst recovery and / or cleaning stages.! 25 Access to the treatment chamber (1) for this activity 26 may be provided by a glove box lid arrangement (9).

27 This allows for function (if necessary), dismantling 28 and scrubbing of instruments or equipment to remove 29 stubborn or hidden contaminants. These are

( 1 subsequently circulated and destroyed in the treatment 2 chamber during the treatment process. Safety 3 interlocks may be employed to minimise any risks to 4 personnel during operation, particularly when 5 introducing target material in to the apparatus.

6 Switching means are provided for deactivating the light I 7 source automatically when the bath lid (9) is opened.

9 Prior cleaning of gross material make take place within 10 the decontamination train, that minimises the volume of 11 material to be decontaminated, and improves throughput.

13 A second embodiment is shown schematically in Figure 2.

14 This apparatus is designed for use in hospitals or 15 larger clinics with high throughput of surgical 16 instruments for decontamination. It is designed for 17 operation by dedicated staff with training in the 18 decontamination of surgical instruments and equipment.

20 The apparatus comprises a treatment chamber (1) having 21 decontamination trays (10) an ultraviolet light source 22 (2) and a medium distribution system (11). Catalyst 23 from the catalyst hopper (6) and / or a catalyst 24 recovery system (4) are introduced into a holding tank 25 (5). The contaminated equipment or product is placed 26 in the decontamination trays (10) and the trays (10) 27 are lowered into the treatment chamber (1). The lid is 28 closed and interlocks engaged before the process is 29 allowed to start. In order to maintain the catalyst in

1 suspension within the medium, the medium is circulated 2 by means of a circulation pump (3) and a medium 3 distribution system (11) having aplurality of rotating 4 spray heads (not shown). The distribution system (11) 5 creates a pressure jet effect that develops a catalyst 6 laden mist or aerosol within the treatment chamber (1) 7 which facilitates optimum contact / interaction between 8 the W light, catalyst and target material on the 9 contaminated instruments. The carrier medium drains to 10 the bottom of the treatment chamber (1) where it is 11 collected in a circulation header tank (12) which in 12 turn feeds the circulation pump (3). At the end of the 13 treatment process any excess catalyst is recovered from 14 the medium via a catalyst recovery system (4). As 15 described above, a process control (not shown) is 16 provided to monitor progress of the treatment by means 17 of off-gas monitor / treatment system (8). Upon I 18 completion of the treatment process, the lid is 19 removed, trays raised and the decontaminated 20 instruments removed.

22 The medium, including suspended catalyst, may be 23 circulated directly through the treatment chamber (1) I 24 from the holding tank (5) during the decontamination 25 process or via the catalyst treatment unit (4) during 26 the catalyst recovery cycle. Carrier medium is sampled 27 for conformity / quality maintenance as described in 28 relation to the previous embodiment. The medium level 29 within the circulation header tank (12) is monitored

( 1 prior to and during operation and is topped-up as required. 4 The third embodiment, shown schematically in Figure 3 5 with details of the treatment chamber arrangement shown 6 in Figures 4 and 5, is designed for either high or low 7 volume destruction of high level big-hazards such as 8 chemical or biological agent materials, prion 9 contaminated material or the like (and may be adapted 10 to handle solid, liquid or gas phase hazardous 11 materials). It is envisaged that such a system would 12 be operated in a restricted area by dedicated and 13 suitably trained staff.

15 The apparatus comprises a series treatment chambers (1) 16 the number and configuration of which may be adapted 17 depending upon the nature and quantity of material to 18 be treated. The target material in a suitable pre 19 prepared state is introduced from a target material 20 hopper (13) under control of metering means (14) into a 21 mixing vessel (15). The carrier medium is fed in to 22 the mixing vessel (15) from the circulation header tank 23 (12) by the circulation pump (3) and catalyst is added I 24 from a catalyst hopper (6). The pre-treatment 25 preparation of the target material may include but need 26 not be limited to the breaking down of solids into 27 smaller particles, the suspension of solid particles in 28 a liquid or the absorption of a gas into a liquid. The 29 target material, medium and catalyst mixture cascades

1 into distribution header (16) from which it enters the 2 treatment chambers (1). This method of controlling the 3 flow of the mixture removes any potential pressure 4 other than the hydrostatic head determined by the 5 relationship between the mixing vessel (15) and the 6 distribution header (16). Each treatment chamber (1) 7 comprises a housing that contains a series of tray-like 8 treatment beds and a light source (2). The treatments g beds are designed to maximise the time which the 10 carrier medium, catalyst and target material mixture is 11 exposed to the W light, as well as promoting the 12 formation of turbulent flow. Typically each treatment 13 bed comprises of a series of channels (17) running back 14 and forth across the bed, each channel (17) containing 15 a textured surface (18) designed to induce turbulent 16 flow within the mixture. Control of the flow in this 17 manner prevents the catalyst and target material from I 18 being shielded (as could occur in a laminar flow 19 situation) and maximises irradiation effectiveness.

20 The treatment beds are configured with a light source 21 (2), optionally shrouded with a mirror, directly 22 overhead. Each treatment bed further comprises a 23 transparent top plate, typically made from quartz or I 24 some other material having suitable light transmission 25 characteristics. The treatment mixture is circulated 26 around the system until the process has been completed 27 or for a suitable duration as dictated by the operator.

28 Any suspended solids, catalyst and other waste products

( 1 are removed via a catalyst / waste treatment system (4) 2 for storage prior to final disposal.

4 Specific modifications may be introduced into the 5 carrier medium composition and flow control in order to 6 create the necessary environment for the target 7 material to be suspended within the medium. For 8 example, rotary, ultrasonic or other stirring / 9 agitation means make be incorporated into the 10 apparatus.

12 The process is controlled using a suitable process 13 monitoring and control system. This includes 14 monitoring the off-gas status by means of an off-gas 15 monitoring / treatment system (8). The off-gas 16 monitoring / treatment system (8) also provides a means 17 for the monitoring and collection / treatment of 18 gaseous reaction products such CO2, NOx, SOx and the 19 like. In order to treat these off-gases specific 20 equipment such as scrubbers and absorbers may be 21 provided. As before suitable analytical techniques can 22 be employed to monitor the course of the treatment and 23 the content of used waste products and used carrier I 24 medium.

26 The invention is not limited to the embodiments herein 27 described which can be varied in construction and 28 detail.

Claims

( 1 CLAIMS

3 1. Apparatus for the treatment of hazardous 4 material and decontamination of items 5 contaminated with such material comprising an 6 operator accessible treatment vessel adapted to 7 hold said hazardous material or contaminated 8 items and a light source capable of irradiating 9 contents within the treatment vessel with a 10 predetermined wavelength of light.

12
2. Apparatus according to Claim 1 wherein the

13 treatment vessel comprises one or more trays 14 for holding the hazardous material or 15 contaminated items, further comprising 16 distribution means for circulating a carrier 17 medium within or through the apparatus.

18 1 19
3. Apparatus according to either one of Claims 1 20 and 2 further comprising monitoring means.

22
4. Apparatus according to Claim 1 further 23 comprising a holding tank capable of holding a 24 carrier medium, a catalyst hopper capable of I 25 holding a catalyst, a mixing vessel 26 facilitating mixing of the carrier medium and 27 the catalyst, wherein the treatment vessel: 28 comprises one or more treatment chambers each 29 having a housing containing a plurality of 30 treatment beds and a light source, and a 31 distribution header for controlling the flow of

1 carrier medium and catalyst into the treatment 2 chambers. 4
5. Apparatus according to Claim 4 wherein each 5 treatment bed comprises means for inducing i 6 turbulent flow within the carrier medium.

8
6. A method for treatment for hazardous material i 9 or decontamination of items contaminated with: 10 such material comprising the step of ll irradiating said material or said items in the 12 presence of a catalyst with light having a: 13 wavelength in the range of from 310 to 400: 14 nanometres. 16
7. A method according to Claim 6 wherein the 17 catalyst is TiO2.

lo
8. A method according to Claim 7 wherein the i 20 catalyst is TiO2 in either rutile or anatase 21 form. 23
9. A method according to any of Claims 6 to 8 24 wherein the irradiation step is carried out at 25 a temperature of between about 15 C to 35 C and 26 a pressure of between about 1 bar to 5 bar.

28
10. A method according to any one of Claims 6 to 9 29 wherein the irradiation step is carried out in 30 an aqueous based carrier medium.