WO2009006702A1

WO2009006702A1 - Method and apparatus for effecting a chemical reaction iii

Info

Publication number: WO2009006702A1
Application number: PCT/AU2008/001022
Authority: WO
Inventors: Ian Andrew Maxwell; Philippe Pascal; Scott Godfrey Cox
Original assignee: VIVA BLU Pty Ltd
Current assignee: VIVA BLU Pty Ltd
Priority date: 2007-07-12
Filing date: 2008-07-11
Publication date: 2009-01-15
Anticipated expiration: 2010-01-12

Abstract

According to the present invention there is provided a method for delivering one or more active species to a reservoir or flow of a contaminated fluid material, thereby to effect a chemical transformation, and to substantially purify said contaminated fluid material. The method comprises the steps of: optionally providing a catalytic substrate; providing a feed comprising one or more predetermined reactants; providing an energy source wherein energy derived therefrom is contactable with a solid, fluid or multi-phase transport medium, and if present, optionally with the catalytic substrate, thereby to provide a species active against said one or more predetermined reactants; and contacting the active species with the feed, thereby to actively effect the predetermined chemical transformation. The method is suitable for remediating organic contaminants such as carcinogenic, endocrine-disrupting and/or unaesthetic compounds, and pathogens, bacteria, organisms, etc. The present invention also provides apparatus for performing such a method.

Description

METHOD AND APPARATUS FOR EFFECTING A CHEMICAL REACTION III

Priority Claim The present application claims priority from each of AU 2007903800 (filed

12 July 2007) and AU 2007905308 (filed 28 September 2007), and incorporates each herein by reference in their entirety.

Field of the Invention The present invention relates to a method and apparatus for effecting a predetermined chemical reaction. More specifically, it relates to a method and apparatus for creating an active species in a reaction vessel and to means for delivering such active species to a fluid reactant bearing an organic and/or pathogenic load.

The invention has been developed primarily as a means of remediating wastewater containing a load of small organic molecules such as the carcinogen 1,4- dioxane, and/or endocrine disrupting compounds such as ./V-nitrosodimethylamine (NDMA), and/or non-aesthetic compounds such as those emitting undesirable odour and/or colour, and/or pathogens/organisms such as bacteria, viruses and protozoa. Although the present invention will be described herein with reference to such applications, it will be appreciated that the invention is not limited to this particular field of use.

Background of the Invention

Any discussion of the prior art throughout the specification should in no way be considered as an admission that such prior art is widely known or forms part of common general knowledge in the field.

In recent years, the treatment and remediation of secondary effluent for the purposes of re-use has become increasingly important. Factors such as increasing population, urbanisation, global warming, changes in weather patterns, and continuing industrial pollution of natural sources of fresh water serve to place often severe limitations on the availability of drinking water. Accordingly, liquid-based effluent is becoming increasingly treated and re-used to both potable and non-potable standards.

Two of the principal contaminants of unpotable water are harmful or undesirable organic compounds (e.g. NDMA) and pathogens. Water contamination is amongst the highest of potential sources for harbouring a pathogen.

Some pathogens have been found responsible for a significant number of fatalities. Of particular note in recent times are the protozoa Cryptosporidium and Giardia lamblia. However, social advances such as food safety, hygiene, and water treatment have reduced the threat from some pathogens.

The past three decades has seen significant changes in how secondary effluent is treated. Specifically, new filter and membrane technologies have supplemented and even replaced more traditional effluent treatments. In addition, new disinfection technologies have also evolved and been applied to supplement the improved membrane technologies.

The removal of certain organic contaminants from secondary effluent may be accomplished using advanced oxygenation processes (AOPs). In chemical terms, "photocatalysis" is the acceleration of a photoreaction in the presence of a catalyst. In catalysed photolysis, light is absorbed by an adsorbed substrate. The essential theory upon which water electrolysis by means of titanium dioxide (TiO₂) is based applies the ability of the catalyst to create electron hole pairs, which generate free radicals able to undergo secondary reactions.

Although effective for the removal of organics, AOPs alone are unsuitable for the removal of pathogens. However, it has been found that pathogens may be effectively removed from a contaminated fluid through applying a secondary disinfection step.

Disinfection, often termed "tertiary treatment" is generally the final step in water purification. Disinfection destroys any pathogens that pass through membrane filters or survive any preceding AOP. Such pathogens may include viruses, bacteria {e.g. Escherichia coli, Campylobacter and shigella), and protozoa (e.g. Giardia lamblia and Cryptosporidia).

The most common disinfection method uses some form of chlorine or its related compounds such as chloramine or chlorine dioxide. Chlorine is a strong oxidant that kills many microorganisms. However, a major drawback to using chlorine or sodium hypochlorite is that each reacts with organic compounds in the water to form potentially harmful levels of chemical by-products, such as trihalo methanes (THMs) and haloacetic acids (HAAs), both of which are carcinogenic and regulated by the US Environmental Protection Agency. The formation of THMs and HAAs is minimised through effective removal of as many organics from the water as possible before disinfection. However, although chlorine is effective in killing bacteria and viruses, it has limited effectiveness against protozoa that form cysts in water, (e.g. Giardia lamblia and Cryptosporidium).

Ozone (O₃) is a relatively unstable molecule that readily gives up one atom of oxygen, providing a powerful oxidising agent toxic to many water-borne organisms. It is a strong, broad-spectrum disinfectant that is widely used throughout Europe as an agent in the destruction of harmful cyst-forming protozoa and almost all other pathogens. However, disinfecting ozone can lead to the formation of its carcinogenic by-product, bromate. Ultra-violet (UV) radiation is very effective at inactivating cysts and other pathogens, as long as the water has a relatively low level of colour such that the UV can pass through without being absorbed. The main drawback to the use of UV radiation is that it consumes relatively high levels of electrical power.

Historically, disinfection using UV radiation was more commonly used in wastewater treatment applications, but is finding increased usage in drinking water treatment, such as in the SODIS process used in Switzerland. Further, it was recently discovered that UV is effective for treating the microorganism Cryptosporidium. Such findings form the basis of US Patent No. 6,565,803, to Bolton, et ah, which relates to the use of UV radiation as a viable method with which to treat drinking water. In the presence of certain molecules, such as ozone or hydrogen peroxide, UV radiation may give rise to potent active species such as hydroxyl radicals. Having one unpaired electron, this free radical can break down organic molecules and even deactivate pathogens, especially when complimented with direct photolysis from the UV light at disinfection wavelengths, such as 254 nm. The present state of the art in the treatment of secondary effluent to potable standards typically includes a first-pass micro filtration or ultrafiltration process, thereby to remove physical or granular contaminants such as dirt or relatively large molecules. Such processes may also remove certain pathogens from the effluent. The first-pass process is typically followed by a Reverse Osmosis (RO) membrane treatment that also removes remaining pathogens, as well as smaller dissolved organic and inorganic molecules. Finally, a disinfection step and/or AOP/s may be present so as to remove any residual pathogens. Such a step typically utilises chlorine, ozone or UV light as the disinfectant, as related above.

Relatively recently, however, it has been shown that low concentrations of certain small organic molecules such as 1,4-dioxane and NDMA have the ability to pass through an RO treatment process or even form as by-products (e.g. THMs) from chemical disinfection treatments. Such molecules pose a significant health risk in that they are known carcinogens. As related above, free radicals are very efficient oxidisers of organic matter.

Photocatalytic activity in TiO₂ has been studied extensively because of its potential use in sterilisation, sanitation, and remediation applications.

TiO₂, when irradiated by UV, reacts with water and oxygen to form reactive species such as hydro xyl and superoxide free radical molecules. The photocatalytic activity of TiO₂ results in thin coatings of the material exhibiting self-cleansing and disinfecting properties under exposure to UV radiation. TiO₂ is desirous as an agent in the remediation of contaminated water due to several factors, including that the process occurs under ambient conditions; TiO₂ is not consumed or degraded; oxidation of organic molecule contaminants to water and CO₂ can be effected to completion; the photocatalyst is inexpensive and has a high turnover; and that TiO₂ can be supported or immobilised on suitable reactor substrates.

In order to remove organic contaminants, some treatment plants have installed UV-peroxide or UV -ozone AOP treatment facilities. In such facilities, peroxide is typically injected into the treated effluent stemming from the initial RO procedure, and this mix is then passed through a high flux of UV light. Such facilities suffer significant issues, primarily associated with cost and chemical exposure. Where a raw secondary effluent contains no organic load, the UV light required to disinfect such a stream is typically 40 mJ/cm²/s or higher. Where such effluent does contain an organic load, peroxide is required to be added, and the peroxidised effluent is then passed through UV light with a flux of typically 150-500 mJ/cm²/s. To achieve such UV intensity, a typical 100 ML/day treatment plant may require 200-250 UV lamps, each costing around US$2,000, and each needing to be replaced annually. In addition, the cost of electricity need to run such a UV source is prohibitive.

United States Patent No. US 6,285,816, to Anderson, et al, relates to a waveguide comprising a transparent substrate and a metal oxide coating. The claims define a waveguide for propagating light of a selected wavelength in an attenuated total reflection mode, the waveguide comprising: a transparent internal reflection element (IRE); and a particulate transition metal oxide coating on one or more surfaces of the internal reflection element, the coating having a boundary parallel to the at least one IRE surface, wherein the coating does not scatter light of the selected wavelength and has a refractive index greater than that of the internal reflection element.

The prior art arrangements, such as that disclosed by Anderson, above, typically suffer from efficiency problems in terms of how one can best deliver an active species (e.g. hydroxyl/superoxide free radicals from TiO₂-induced photocatalysis of light) to the contaminated species undergoing remediation. To this end, the relatively inefficient systems disclosed in the prior art result in a relatively high cost per unit volume of remediated product. It will be appreciated that where the remediated product is potable water for consumer sale, the net result of such a relatively inefficient system is a product that cannot be priced competitively against water bottled at source.

One of the principle factors influencing the efficiency of such a system is the means by which the active species is brought into contact with the contaminant species. Where the raw active species is, for instance, light, such media may be solid, liquid, gas, or combinations thereof. The present invention relates to the adaptation of such media toward a relatively increased delivery efficiency of the active or excitable species.

It is an object of the present invention to overcome or ameliorate at least one of the disadvantages of the prior art, or to provide a useful alternative. It is an object of a preferred form of the present invention to provide a means of effecting a predetermined chemical transformation in a modular apparatus, said modular apparatus being relatively cheap to construct, maintain and operate. It is an object of a particularly preferred form of the present invention to provide means for remediating secondary effluent initially containing an organic load, preferably to a potable standard. It is a further object of the present invention, in another preferred form, to provide a relatively cost effective means of achieving same. It is yet another object of the present invention in but another preferred form to provide means for delivering one or more active species to a reservoir or flow of a contaminated fluid. It is a further object of the present invention, in a further preferred form, to provide a relatively cost effective means of achieving same. It is yet another object of the present invention in but another preferred form to provide means for delivering one or more active species to a reservoir or flow of a contaminated fluid, wherein said means employs an inventive configuration to increase the efficiency of what is otherwise a counter- intuitive system. It is a farther object of the present invention, in a further preferred form, to provide a relatively cost effective means of achieving same.

Summary of the Invention According to a first aspect of the present invention there is provided a method for effecting transformation of a reactant species, said method comprising the steps of: providing a catalytic substrate; providing a feed comprising said reactant species; providing an energy source wherein energy derived therefrom is contactable via a transport medium with said catalytic substrate, thereby to provide a species active against said reactant species; and contacting said active species with said reactant species, thereby to actively effect said transformation.

According to a second aspect of the present invention there is provided a method for creating one or more active species in a reaction vessel, thereby to effect transformation of a reactant species, said method comprising the steps of: providing a feed to said reaction vessel, said feed comprising one or more reactant species; providing an energy source, thereby to produce incident energy therefrom; providing a transport medium communicable between said reaction vessel and said energy source to deliver said incident energy to said one or more reactant species, thereby to actively effect said transformation.

According to a third aspect of the present invention there is provided an apparatus for effecting transformation of a reactant species, said apparatus comprising: a catalytic substrate; means for providing a feed comprising one or more said reactant species; an energy source; a transport medium through which energy derived from said energy source is contactable with said catalytic substrate, thereby to provide a species active against said one or more reactant species; and means for contacting said active species with said reactant species, thereby to actively effect said transformation.

According to a fourth aspect of the present invention there is provided an apparatus for creating one or more active species in a reaction vessel, thereby to effect transformation of a reactant species, said apparatus comprising: means for providing a feed to said reaction vessel, said feed comprising one or more reactant species; an energy source, thereby to produce incident energy therefrom; a transport medium communicable between said reaction vessel and said energy source, thereby to deliver said incident energy proximal with said one or more reactant species; and means for contacting said incident energy with said one or more reactant species, thereby to actively effect said transformation.

Although preferred embodiments of the present invention will been described with reference to specific examples and/or aspects of the invention, it will be appreciated by those skilled in the art that the invention may be embodied in many other forms. In particular, features of any one of the various described examples may be provided in any combination in any of the other described examples.

Preferably, said transport medium is a waveguide. More preferably, said waveguide is an optical waveguide. Preferably, said waveguide acts both as said transport medium and as a substrate for catalytic material applied to the surface thereof.

In an embodiment, said waveguide is adapted to act either as said transport medium and/or as a substrate for said catalytic material and/or as a fluid flow channel defining means.

Preferably, said waveguide comprises a single material. Alternatively, said waveguide comprises a plurality of materials. In this latter preferred embodiment, said plurality of materials are of differing refractive indices, thereby to relatively enhance the waveguiding efficiency of said waveguide.

In an embodiment, said waveguide may comprise, at its surface or in the bulk of its material, scattering centres, reflective elements, diffractive elements, areas of differing thicknesses, or a combination thereof, thereby to facilitate incident light being shifted out of the plane of said waveguide.

Preferably, said waveguide comprises a disc. Alternatively, said waveguide comprises a helix or even a double coincident (e.g. DNA) or multiple helix, thereby to provide a manifold of channels, effectively reducing the required module length by a factor of two (for two parallel channels), and three (for three parallel channels), etc.

Preferably, said disc is substantially UV -transparent. Preferably, said disc is formed of a plastics material capable of appreciably transmitting ultra-violet light. More preferably still, said substantially UV-transparent disc is quartz or polymer. In an embodiment, said waveguide comprises a plurality of discs, thereby to define a module. Preferably, said plurality of discs are spaced apart by discrete spacer units. Preferably, each said disc has a hole substantially at the centre thereof.

More preferably, said plurality of discs are configured such that each said hole aligns to define a central channel. Alternatively, the helix comprises a channel portion. Preferably, said central channel is adapted to house said energy source.

Preferably, said energy source is configured to extend substantially along the length of said channel.

In an embodiment, said waveguide is configured to provide a relatively increased surface area per unit reactor fluid volume. Preferably, said plurality of discs numbers of the order 10². More preferably, said plurality of discs numbers substantially 300. More preferably still, said plurality of discs have a surface area of substantially 8 m². More preferably, said plurality of discs each have a surface area substantially of the order 10^"' m². In an embodiment, said channel is substantially 1.2 m in length. Preferably, said discrete spacer units hold adjacent discs between substantially

0.1 and 0.5 mm apart. More preferably, said discrete spacer units hold adjacent discs substantially 0.1 mm apart.

In an embodiment, said catalytic substrate is a photocatalytic substrate. Preferably, said photocatalytic substrate is selected from the group consisting of: TiO₂, zinc oxide (ZnO), CdS and tungsten oxide (WO₃). More preferably, said photocatalytic substrate is TiO₂.

Preferably, said energy is UV light derived from a UV source. Preferably, said UV source is a tube or an LED. Alternatively, said UV source is sunlight, said sunlight being piped into the reactor volume using a light pipe, wherein the incident sunlight is first collected using a solar collector. Preferably, said UV source is focused on the outside of the module.

In an embodiment, said UV source is protected from said fluid by using a substantially UV-transparent tubing. Preferably, said UV source and/or said UV- transparent tubing comprises anti-reflective coatings or structure, thereby to prevent UV being reflected back into said UV source and being wasted.

In an embodiment, said energy source is a UV lamp. Preferably, said UV lamp is of substantially 15 W in power. Preferably, said light comprises one or more wavelengths within the range of approximately 200-400 run. In an embodiment, said active species is an excited species. Preferably, said excited species are free radicals and TiO₂ electron holes.

Preferably, said catalytic material is provided as a coating over one or more surfaces of said waveguide. Preferably, said coating is adhered to said waveguide via solid phase, gas phase and/or liquid phase deposition techniques. Preferably, said deposition techniques comprise chemical grafting, annealing, adhesive, etching, extrusion, moulding, dip coating, sputter coating, slot coating, lamination, or a combination thereof.

In an embodiment, said feed is a fluid. Preferably, said fluid is a liquid, gas, or a combination thereof. Preferably, said fluid is a fluid effluent, said method thereby operative to treat at least a portion of said fluid effluent. More preferably, said fluid effluent is a contaminated or polluted liquid, gas and/or steam.

Preferably, said liquid, gas and/or steam comprises said one or more predetermined reactant species in solution state. Preferably, said liquid is water.

Preferably, said solution comprises said one or more predetermined reactant species in aqueous phase. Preferably, said contaminated or polluted liquid comprises one or more organic contaminants.

In an embodiment, said fluid is chemical. Preferably, said chemical is a chemical solvent, wherein a predetermined photocatalytic reaction is used as part of a synthetic route. More preferably, said fluid is wet gas from a combustion engine or other, said method thereby effective to relatively reduce emissions from said engine. More preferably, zirconia is incorporated as catalyst. Alternatively, said method further includes a catalyst selected from the group consisting of: TiO₂, zinc oxide (ZnO), CdS and tungsten oxide (WO3). Alternatively, said method further includes a catalyst selected from the group consisting of: platinum, palladium, rhodium, cerium, iron, manganese and nickel.

In an embodiment, said one or more organic contaminants comprise organic molecules and organisms. Preferably, said one or more organisms comprise bacteria, protozoa and/or viruses. Preferably, said organic molecules comprise carcinogenic, endocrine-disrupting and/or unaesthetic compounds. More preferably, said carcinogenic, endocrine-disrupting and/or unaesthetic compounds comprise 1,4- dioxane and/or 7V-nitrosodimethylamine (NDMA).

In an embodiment, the apparatus further comprises an outlet port remote from an inlet port, thereby to facilitate flow of said feed therebetween. Alternatively, the apparatus further comprises an outlet port integral with an inlet port, thereby to facilitate said method to operate on a batch basis.

In an embodiment, said waveguide is configurable so as to optimise the proportion of said active species relative to the composition of said feed. Preferably, said predetermined transformation is effected by photocatalysis and/or photolysis. Preferably, said photocatalysis is effected from incident light interacting with a

TiO₂ coating upon one or more surfaces of said waveguide. Preferably, said photolysis is effected from incident light passing through one or more uncoated surfaces upon said waveguide.

In a preferred embodiment, said waveguide comprises a continuous helix. Preferably, said continuous helix is a discrete repeating unit. Alternatively, said continuous helix comprises a plurality of adjoined units. Preferably, successive winds of said helix are spaced by one or more discrete spacer units.

Preferably, said incident energy is a species active against said one or more predetermined reactant species. In an embodiment, the association of said catalytic substrate with said transport medium is such that said catalytic substrate is coated over at least part of one or more surfaces of said transport medium.

Preferably, titanium dioxide is coated upon one or more surfaces of said catalytic substrate to a uniform or non-uniform thickness of up to approximately 20 microns. More preferably, titanium dioxide is coated upon one or more surfaces of said catalytic substrate to a uniform or non-uniform thickness of about 0.1 to 15 microns. More preferably still, titanium dioxide is coated upon one or more surfaces of said catalytic substrate to a uniform or non-uniform thickness of about 0.1 to 5 microns. Preferably, said waveguide is configured to provide optimal contact time of said feed with said active species. Preferably, said transformation takes place within a modular apparatus. Preferably, said energy source is spaced from or proximal with said catalytic substrate. Preferably, said energy source is directly coupled with said catalytic substrate.

In an embodiment, said catalytic substrate is applied to one or more auxiliary surfaces spaced from said transport medium to define a reactor volume comprising said one or more reactant species, said incident energy thereby able to perform a photolytic transformation prior to contacting with said photocatalytic surface following which a photocatalytic transformation may be effected.

Preferably, said one or more auxiliary surfaces is substantially reflective such that energy passing through said catalytic surface is reflected back toward said reactor volume.

Preferably, said one or more auxiliary surfaces is substantially transmissive such that energy passing through said catalytic surface is directed toward a further reactor volume.

The inventive methods preferably further comprise the step of adding one or more predetermined additive to said feed prior to introducing said feed to said active species. Preferably, said additive is selected from the group consisting of: chlorine, a chlorine-containing additive, a chlorine-derived additive, hydrogen peroxide, ozone and additive comprising active oxygen. More preferably, said additive is chlorine, a chlorine-containing or a chlorine-derived additive.

The inventive apparatus preferably further includes means for adding one or more predetermined additive to said feed prior to introducing said feed to said active species.

Preferably, said additive is selected from the group consisting of: chlorine, a chlorine-containing additive, a chlorine-derived additive, peroxide, ozone and additive comprising active oxygen. Preferably, said additive is chlorine, a chlorine-containing or a chlorine-derived additive. In an embodiment, said waveguide comprises a lens, thereby to focus said energy in a predetermined manner. Alternatively, said waveguide comprises a reflecting element, thereby to redirect said energy in a predetermined manner.

In general terms, the present invention provides means suitable for the treatment of organics-containing and/or pathogen/microorganism-containing effluent, such that the organics and/or pathogens are removed with relatively high efficiency. The inventive process and apparatus is scalable to a treatment plant that requires relatively low investment and ongoing running costs.

By "removed with relatively high efficiency" is intended to mean that the organics and/or the pathogens are reduced in concentration by between approximately one and four orders of magnitude.

By "waveguide" is intended to mean a transport medium, or transport media, for an active, or precursor-active species such as light. It will be appreciated that "waveguide" in the presently inventive sense may be solid, liquid, gas, or combinations thereof. It will be further appreciated that a "waveguide" can be any means or media though which such active or precursor-active species is transported from source to a space proximal with the contaminant species.

One feature of the inventive process and apparatus relates to the use of photocatalytic processes to create free radicals in effluent water. UV light interacting with TiO₂ causes a photoreaction between water and oxygen to generate free radicals. These radicals and the holes created at the TiO₂ surface are reactive with the organic contaminants to initiate their decomposition into harmless products such as carbon dioxide and water.

Whilst other inventors have sought to use such TiO₂/UV systems in the treatment of water, it has proved difficult to develop a system where the light required to initiate the sought photochemistry is brought efficiently to the reaction vessel. To this end, the principal limitations include:

Firstly, since contaminated water itself absorbs and scatters UV light, it has been considered preferable in the art that the light itself comes into contact the photocatalyst and/or contaminant species without first travelling through the contaminated water. However, there is also an abundance of literature proposing various configurations of the opposite arrangement such as a water-based transport medium, or the use of TiO₂ sols suspended in water, or even a TiO₂ carrier system.

Contrary to popular opinion as to the undesirability of a liquid or water transport medium, one embodiment of the present invention does require the energy to travel through water. In this embodiment, the catalytic substrate, if present, is applied to one or more auxiliary surfaces spaced from the transport medium, thereby to define a reactor volume comprising the one or more reactant species, the incident energy is thereby able to perform a photolytic transformation or to contact with said photocatalytic surface following which a photocatalytic transformation may be effected. The one or more auxiliary surfaces may be substantially reflective such that energy passing through the catalytic surface is reflected back toward the reactor volume, or that light potentially active in UV photolysis is reflected back into the reaction vessel from a reflective, non-coated surface.

Secondly, it has proven difficult to place the photocatalyst optimally within a photochemical system. Known techniques include placing the TiO₂ in a suspension, with the appreciably negative impact that the suspension itself limits the path-length of UV light through the solution due to light absorption and scattering. Further, a TiO₂ suspension is difficult to manage and maintain in a flow- thro ugh system. One alternative, as proposed according to the present invention, is to affix any TiO₂ on a surface accessible to the UV, whereby the UV light may or may not have to travel through water in order to arrive at the TiO₂. It will be appreciated that a relatively minimal path length is desirous. Thirdly, the reactive species produced by TiO₂ induced photocatalysis are active over a limited distance from where they are generated, as such species have a high propensity to recombine to form non-reactive species. Hence, there is an optimum volume of water, or reactor fluid, around the photooxidation site that ensures chemical oxidation of the effluent organic and/or pathogen species is effected. The present invention seeks to optimise the balance between photocatalytic surface area and reactor volume such that the resultant method and apparatus are relatively efficient with respect to known systems.

Fourthly, it is problematic as to precisely how to get UV into a water flow system. For example, if water passes through an optically clear pipe, the water can be irradiated with UV. However, because UV is absorbed by water and also because radicals can recombine, there is an optimum pathlength for the UV light applicable to the present invention.

From the above discussion, it is clear that the four key features in any such system of remediating organics-containing and/or pathogen-containing secondary effluent are: the transport medium/waveguide, the solvent/solute (generally, water/organics), energy (generally, light) and the presence/absence of photocatalytic material. The present invention seeks to combine these in a manner that provides for a relatively simple and efficient treatment of secondary effluent to both potable and non-potable standards. Such a system is designed to optimise the efficiency with which the UV light is utilised; optimise the surface area of the photocatalyst; enable the photocatalyst to be bypassed in favour of a photo lytic disinfection step, so as to achieve photocatalysis and/or photolysis as the composition of the contaminated feed may require or dictate; and possess the ability to tailor the reactor volume and/or flow rate of water. When each of these elements is optimised, the unit cost of removing the organic or pathogenic load in the raw effluent is relatively minimised.

The basic components of the present invention include: An optical transporter comprising an optical fiber or a contorted, preferably helical, optical sheet. These can be made of any optically clear materials, most usefully comprising an optically clear path in the UV. Typically, such optical transporters are made of inorganic glasses or polymeric materials such as acrylics or cyclo-olefin copolymers. In an embodiment, the core of an optical transporter comprises a higher refractive index material, optionally surrounded by a cladding of lower refractive index material, thereby to help guide light. However, in an alternative embodiment, the cladding may be a higher refractive index material such that light is preferentially withdrawn from the waveguide. Potential additional elements include light scattering functionality in the optical transporter in order to distribute the UV light substantially orthogonal to the incident light path. Such scattering ability may be achieved via the inclusion of small particles or physical defects, and will be elaborated upon, below.

In a preferred embodiment, the optical transporter is a helical waveguide that propagates light from a light source to the photocatalytic sheet. In another preferred embodiment, the optical transporter is a plurality of spaced discrete discs each having an aligned central hole portion defining a channel in which the light source is housed. The light source can be any light source capable of producing a beam of the desired wavelength, although preferred embodiments of the present invention may deploy a UV lamp tube or one or more light emitting diodes (LEDs) or natural sunlight. The waveguide advantageously uses common photonics techniques to ensure that essentially all the light is propagated to the sheet. The waveguide may allow the light source to be remote from the photocatalytic sheets that are in the reactor.

In a particularly preferred embodiment of the present invention, the optical transporter is liquid and/or gaseous. In such embodiments, the incident light may first travel through an airspace, through a thin solid interface, and then into the liquid/water medium in which the contaminants are housed. Alternatively, the solid interface is adjacent, abutting, or integral with the light source such that the aforementioned passage through an airspace is avoided. Nonetheless, such an embodiment provides an inventive solution to the otherwise undesirable configuration of the light passing through a liquid/water "waveguide". For the purposes of the ensuing discussion, such a configuration may be termed an "inverse waveguide".

Using the "inverse waveguide" configuration removes the necessity to provide the plastic/acrylic waveguide configuration described elsewhere in the Applicant's patent portfolio and also in other embodiments of the present invention. Nonetheless, it remains necessary to provide an appropriate internal surface area such that a sufficient quantity or surface area of photocatalytic substrate (generally, TiO₂) is provided and/or such that a sufficient area of reflective surface is provided such that the incident (for photolysis) or excited (for photocatalysis) light contacting with the reflective surface (e.g. aluminium) is redirected back into the reaction vessel for a second or subsequent pass. Thus, it will be appreciated that any internal configuration of reflective surfaces and/or photocatalytic surfaces about which the "inverse waveguide" medium can reside and/or flow is applicable to the present invention. Such examples may include small cavities, long chutes, or one or more open reservoir configurations selectable according to factors such as the organic load of the contaminant material, and whether the system is intended to work on a batch or continuous flow-through basis.

In an alternative embodiment, the reflective and/or photocatalytic surface area may be adhered to the surface of the one or more acrylic discs or a helix disclosed in other preferred embodiments of the present invention. This would allow a combination-waveguiding effect, or in certain configurations would allow the incident light to be transported proximal with the contaminant species preferentially through either the solid or liquid waveguides according to the exact system configuration.

In another alternative embodiment, such discs/helix may again be used, but with the end adjacent the light source being blocked from communicating the light from source to reaction vessel. In such instances, an opaque or reflective surface may be applied to the end of the disc/helix through which the light would otherwise be communicated.

It will be appreciated that the disclosed configuration is applicable to disc, helix, vane, wedge-shaped, screwed and Swiss-roll-type configurations, each of which is within the patent portfolio of the Applicant.

The present invention may also include a photocatalytic material placed upon the surface of the optical transporter. For example, TiO₂ can be coated upon one or more exterior surfaces of a polymeric optical disc, helix, or indeed any planar, curved or complex surface providing the sought surface area and/or flow through dynamics. Such a coating may be imparted by a variety of means, including solvent-based coating techniques. Alternatively, such a coating can be achieved during production of the optical fibers by bringing a cooling optical fiber/sheet into contact with TiO₂ powder, or by high-temperature annealing of the TiO₂ so as to bind the TiO₂ particles to each other. Alternatively, the photocatalytic material may be remote from the waveguide, as shown in Figure 4 of the accompanying drawings. The TiO₂ may be either adhered direct to the surface of the fiber/sheet, or have a reflective surface interspersed therebetween.

Coating of the optical transporter and/or coating of the functionality providing interior surface area may be further achieved through use of a porous silica as a binding agent for coating the TiO₂. Such a process comprises mixing pre-formed TiO₂ nanoparticles, said nanoparticles themselves comprising an approximate anatase-to- rutile ratio of 95:5, with a mix of siloxane molecules that when cured form a nano porous silica. However, one skilled in the art will appreciate that a variety of TiO₂ compositions and coating techniques are applicable to the present invention.

Further coating techniques may involve embedding agglomerates of TiO₂ onto the surface of the plastic or glass optical transporter, and then grinding back the surface to expose the agglomerates if necessary. Many other known means of achieving a functional coating of a photocatalytic material onto an optical transporter may be employed.

In a preferred embodiment, photocatalytic discs or a photocatalytic helix comprising a non-photocatalytic, optical substrate, and having a surface layer of TiO₂, comes into contact with the fluid that is to be remediated. The substrate is made of a material that is substantially optically clear, thereby allowing light of a wavelength anywhere from about 200 nm to about 400 nm to pass through its entirety.

The present invention further comprises a UV light source, preferably housed either within the channel defined by a plurality of aligned, centrally holed, spaced discs, or within the central channel defined by a helical waveguide. Where neither discs nor a helix are employed, it will be appreciated that the energy source is most preferably positioned toward the general centre of the reaction vessel such that the incident light has a relatively small distance through which it must travel in the water/liquid "inverse waveguide" configuration.

An optical transport layer that allows the distribution of light down the optical transporter may scatter incident light substantially orthogonal from any TiO₂ coating and produce the sought radicals in water. For undoped TiO₂, the light energy source is most preferably a light beam of 250 to 350 nm wavelength. For doped TiO₂, the wavelength range may increase towards the visible spectrum, typically by 10 to 100 nm. The present invention may also comprise a reactor vessel preferably having an inlet and an outlet, to allow a raw aqueous gas or liquid feed to enter the vessel, and a treated flow to exit the vessel. Alternatively, the inlet is integral with the outlet, thereby to facilitate a batch treatment process. The inside of the vessel allows for an advantageous arrangement of photocatalyst to be employed, allowing the raw feed optimum contact time with the photocatalytic surface.

The reactor vessel also comprises a housing having an interior surface area, which may be a regular or complex surface. The interior surface area may be equipped over some or substantially its entirety with the reflective surface and/or the photocatalytic surface. The precise surface area and configuration of the interior surface area adopted is a balance between fluid dynamics and surface area.

More preferably still, the end/s of any solid phase optical transporter can be fitted or equipped with a mirrored surface to reflect any incident light that had not been used on its first pass through the substrate. Extension of this concept into the liquid or gas phase "inverse waveguide" configurations is by way of mirrored surfaces on any of the interior surfaces.

Depending upon the precise configuration adopted (e.g. discs, helix, the "inverse waveguide", TiO₂ coated or uncoated, and the relative ratio thereof), both photocatalysis and photolysis may occur. However, the ratio will change depending upon the configuration and wavelength/s of UV light used. This means the system can be optimised to the application at hand. It also means that substantially an optimum amount of light is used.

According to a fifth aspect of the present invention there is provided a method for effecting transformation of a reactant species, said method comprising the steps of: providing a catalytic substrate; providing a feed comprising said reactant species; providing an energy source wherein energy derived therefrom is contactable via a fluid transport medium with said catalytic substrate, thereby to provide a species active against said reactant species; and contacting said active species with said reactant species, thereby to actively effect said transformation.

According to a sixth aspect of the present invention there is provided a method for creating one or more active species in a reaction vessel, thereby to effect transformation of a reactant species, said method comprising the steps of: providing a feed to said reaction vessel, said feed comprising one or more reactant species; providing an energy source, thereby to produce incident energy therefrom; providing a fluid transport medium communicable between said reaction vessel and said energy source to deliver said incident energy to said one or more reactant species, thereby to actively effect said transformation.

According to a seventh aspect of the present invention there is provided an apparatus for effecting transformation of a reactant species, said apparatus comprising: a catalytic substrate; means for providing a feed comprising one or more said reactant species; an energy source; a fluid transport medium through which energy derived from said energy source is contactable with said catalytic substrate, thereby to provide a species active against said one or more reactant species; and means for contacting said active species with said reactant species, thereby to actively effect said transformation.

According to an eighth aspect of the present invention there is provided an apparatus for creating one or more active species in a reaction vessel, thereby to effect transformation of a reactant species, said apparatus comprising: means for providing a feed to said reaction vessel, said feed comprising one or more reactant species; an energy source, thereby to produce incident energy therefrom; a fluid transport medium communicable between said reaction vessel and said energy source, thereby to deliver said incident energy proximal with said one or more reactant species; and means for contacting said incident energy with said one or more reactant species, thereby to actively effect said transformation. Preferred embodiments according to the fifth through eighth aspects of the present invention include: Preferably, said fluid transport medium is a waveguide. More preferably, said fluid waveguide is a liquid waveguide. More preferably, said liquid waveguide comprises water. More preferably still, said water is contaminated water.

Preferably, said energy source is proximal with said catalytic substrate, thereby to selectively control the pathlength therebetween.

Preferably, the proximity of said energy source to said catalytic substrate is such that energy derived from said energy source is not significantly dissipated within said fluid transport medium prior to contacting with said one or more reactant species. Preferably, said reaction vessel or said apparatus is provided with interior functionality, thereby to relatively increase the interior surface area and/or provide manipulable flow characteristics within said reaction vessel or said apparatus.

Preferably, said interior functionality is selected from the group consisting of: one or more discrete discs, one or more discrete or adjoined helical elements, one or more nodules, one or more complex surfaces, and combinations thereof. Preferably, said interior functionality provides a complementary or synergistic transport medium to said fluid transport medium.

Preferably, said interior functionality is not adapted to provides a complementary or synergistic transport medium to said fluid transport medium.

Brief Description of the Drawings

A preferred embodiment of the present invention will now be described by way of example and only with reference to the accompanying drawings and examples in which:

Figure 1 is a schematic representation of an "inverse waveguide" according to the present invention. Incident light is transmitted from a preferably centrally-located light source into the liquid medium through a solid interface, itself preferably integral with said light source. Light contacting with the contaminants without first interacting with surface-coated TiO₂ may be active to effect UV photolysis, whereas that excited as described above may be active to induce photocatalytic conversion of the contaminant. In the illustrated embodiment, a series of discs act to provide additional internal surface area. The discs are coated with aluminium to reflect incident light for photolysis and/or TiO₂, to photo-excite the incident light for photocatalytic conversion of the contaminant molecules. In this embodiment, it will be appreciated that the discs may or may not have "waveguiding" properties and that the principal waveguide or transport medium is the water in which the contaminant molecules are dispersed.

Figure 2 is a schematic representation of an alternative "inverse waveguide" according to the present invention. In this embodiment, the discs present in the embodiment of Figure 1 are absent, and the interior surface of the reaction vessel is coated with aluminium/TiO₂, as appropriate.

Figure 3 is an exploded perspective view of a module according to another preferred embodiment of the present invention. In this embodiment, a plurality of discrete surface-area providing discs is spaced apart by discrete spacer units, thereby to define cavities filled by the "inverse waveguide" (i.e. water). The discrete discs and/or the discrete spacer units may or may not be coated with TiO₂ depending upon the ratio of photo lysis/photocatalysis sought. Preferably, the discrete spacer units are coated with one or more reflective surfaces such that light contacting with said surface is reflected back into the reaction vessel. The arrangement of discs/spacer units is housed within a cylindrical reaction chamber through which the raw feed either flows or is batched. The interior wall of the cylindrical reaction chamber is preferably coated with a reflective surface and/or photocatalytic material, again, depending upon the ratio of photolysis to photocatalysis required for a given feed. It will be appreciated that the incident light is transported proximal with the contaminants via the water medium, or the "inverse waveguide". Figure 4 is a perspective view of a helical element according to a preferred embodiment of the present invention. In this embodiment, the helical element does not function as a waveguide, but serves merely to provide interior surface area to the reaction vessel. In such instances, the conducting ends of the helical element are coated with an opaque or mirrored surface to prevent the transmission of light. The exterior surfaces are coated with TiO₂ and/or a mirrored finish such that incident light travelling through the liquid/water "inverse waveguide" and contacting with the surface is either excited or reflected, respectively, thereby providing for a selected one or more or photocatalysis and photolysis. The helix may comprise several such discrete elements adjoined so as to create a substantially continuous helix, or one cast or moulded continuous helical element. The surface are may be coated in part or in its entirety. The helical element may be constructed of any material. Preferably, the helix extends about a central core portion defining a channel in which the UV lamp is housed. Figure 5 is a perspective view of a helical waveguide element according to a preferred embodiment of the present invention. The waveguide helix may comprise several such discrete elements adjoined so as to create the waveguide helix, or a cast or moulded continuous helical element. The helical element is preferably constructed of an acrylic material so as to be substantially UV transparent. The respective surfaces of the helical element may be selectively coated with a photocatalytic material such as TiO₂ and/or left uncoated so as to facilitate UV photolysis of pathogens and/or microorganisms. The helix extends about a central core portion defining a channel in which the UV lamp is housed.

Figure 6 is an exploded perspective view of a module according to another preferred embodiment of the present invention. In this embodiment, a plurality of discrete waveguiding discs is spaced apart by discrete spacer units. The discrete waveguiding discs and/or the discrete spacer units may or may not be coated with TiO₂ depending upon the ratio of photolysis to photocatalysis sought. Preferably, the discrete spacer units are coated with one or more reflective surface such that light contacting with said surface is reflected back into the reaction vessel. The arrangement of discs/spacer units is housed within a cylindrical reaction chamber through which the raw feed either flows or is batched. The interior wall of the cylindrical reaction chamber is preferably coated with a reflective surface and/or photocatalytic material, again, depending upon the ratio of photolysis to photocatalysis required for a given feed.

Figure 7 depicts a bank of reaction modules configurable to work either in series or in parallel. Each module is preferably approximately 200 mm in diameter, around 1.2 m in length, comprises one or more 15 W UV lamp/s housed within the channel portion and, where discrete discs are used, comprises approximately 300 discs, each spaced around 0.5 mm apart, and comprising around 8 m² in surface area.

Figure 8 is a side schematic view of a modified waveguide according to a preferred embodiment of the present invention. The waveguide comprises two parallel plates spaced apart to define a cavity therebetween. The cavity may be filled with any one or more materials of the solid, liquid or gas phase. The distal end of the waveguide is sealed to retain the waveguide medium, and mirrored such that unused light is reflected back into the waveguide for transmission into the reaction vessel on a second or subsequent pass; and

Figure 9 is a side schematic view of a modified waveguide/spacer unit according to a preferred embodiment of the present invention. In this embodiment, UV light propagates along and is scattered out of an uncoated acrylic waveguide. The incident UV then propagates through the feed flow whereupon it performs UV photolysis upon certain organic molecules (such as NDMA) and any pathogens/micro-organisms present within the feed. UV that is not employed for photolysis or absorbed into the water propagates through the feed and contacts with the photocatalytic surface/s coated upon the spacer units. UV transmitted through the approximate 10 micron TiO₂ thickness is then reflected back into the reaction vessel. UV contacting with the photocatalytic surface be it on the first or subsequent pass, is catalysed to an excited species that creates radicals in water, thereby to effect decomposition of any organic load present in the feed and/or inactivate any pathogens/micro-organisms in the feed.

Preferred Embodiment of the Invention

According to preferred "inverse waveguide" embodiments of the present invention represented by Figures 1 to 4 of the accompanying drawings, the present invention consists in an apparatus comprising a reaction vessel 1 having inlet 2 and outlet 3 ports between which a contaminated liquid 4 may flow or indeed be transferable on a batch basis.

The reaction vessel 1 further comprises a substantially centrally located, longitudinally-extending energy source 5 in the form of a UV lamp. The light source 5 is sealed within a solid membrane 6 to avoid contacting with the liquid 4. The interior walls 7 of the reaction vessel 1 are coated with aluminium 8 and/or TiO₂ 9 to provide for photolysis and/or photocatalysis as described above.

In the embodiment illustrated in Figure 1, additional internal surface area is provided by way of a plurality of discrete discs 10 extending substantially normal to the longitudinal axis of the light source 5, thereby to define a corresponding plurality of cavities 1 1. it will be appreciated that relative to the embodiment illustrated in

Figure 2, in which this plurality of discs 10 is absent, the cavities 11 serve to reduce the path length through which the incident light energy must propagate through the liquid "inverse waveguide" medium, thereby increasing overall operational efficiency.

An alternative means with which to increase interior surface area is illustrated in Figure 4. In this embodiment, the discrete discs are replaced by one or more helical elements 12, which may be optionally adjoined with each other at their lip portions 13.

It will be appreciated that the resultant helix may serve to enhance flow-through characteristics such that it may define a conduit through which contaminated liquid 4 may flow from inlet port 2 to outlet port 3.

An exploded view of a modular "inverse waveguide" embodiment is provided in Figure 3 of the accompanying drawings. In this embodiment, a plurality of discrete surface-area providing discs 10 are spaced apart by discrete spacer units 13, thereby to define cavities 11 filled by the "inverse waveguide" (i.e. water 4). The discrete discs and/or the discrete spacer units may or may not be coated with TiO₂ depending upon the ratio of photolysis to photocatalysis sought. Preferably, the discrete spacer units and/or discrete discs 10 are coated with one or more reflective surface 9 such that light contacting with said surface is reflected back into the reaction vessel. The arrangement of discs/spacer units is housed within a cylindrical reaction chamber 1 through which the raw feed either flows via ports 2 and 3 or is batched. The interior wall 7 of the cylindrical reaction chamber is preferably coated with a reflective surface 9 and/or photocatalytic material 8, again, depending upon the ratio of photolysis to photocatalysis required for a given feed. The incident light is transported proximal with the contaminants via the water medium 4, or the "inverse waveguide".

It will be appreciated that other configurations of the generalised "inverse waveguide" embodiment are within the spirit and scope of the present invention. For instance, the "inverse waveguide" may comprise gas, or another flowable fluid material; and the light source need not be centrally-located and longitudinally- extending. Moreover, a "combination" waveguide is possible such that the discrete discs 10 do have a waveguiding function which acts in synergy with that of the liquid medium 4.

In the alternative embodiments now described, equivalent features have been ascribed the same numbers as given in respect of the embodiments described with reference to Figures 1 to 4.

Another preferred embodiment of the apparatus according to the present invention is illustrated in Figures 5 and 6. Such an embodiment employs a "regular" or "traditional" waveguide and comprises a catalytic substrate, which is preferably a photocatalytic substrate 8 or a mirrored surface 9, the photocatalytic substrate most preferably being TiO₂, in the form of anatase, rutile or a combination thereof.

The apparatus also comprises means 2 for providing a feed 14 comprising one or more predetermined reactants 15. The feed is a fluid, most preferably being a liquid 4, gas, or a combination thereof. More preferably, the fluid is a fluid effluent, with the method thereby operative to remediate at least a portion of the fluid effluent. In a particularly preferred embodiment, said fluid effluent is a contaminated or polluted liquid 4, gas and/or steam. The liquid, gas and/or steam comprises one or more predetermined reactants 15 in solution and/or undissolved state. Most preferably, the liquid is water 4 and the effluent comprises organic molecules and/or pathogens/micro-organisms 15.

The means for providing a feed includes provision of an outlet port 3 remote from an inlet port 2, thereby to facilitate flow of said feed 14 therebetween. Alternatively, the inventive apparatus includes provision of an outlet port 3 integral with an inlet port 2, thereby to facilitate the method to operate on a batch basis. The apparatus also comprises an energy source 5 spaced from, or proximal with the catalytic substrate. More preferably, the energy source 5 is directly coupled with the catalytic substrate 8, 9. The energy is light, most preferably comprising one or more wavelengths within the range of approximately 200-400 nm. In the present invention, the light source 5 is a UV lamp of 15 W power. The UV lamp is housed in a channel 16 defined by the central core 17 of a helical waveguide 10, or the central core 17 of aligned centre holes of adjacent discrete waveguides 10.

The apparatus also comprises a transport medium in the form of a waveguide 4 through which energy derived from the energy source 5 is contactable with the catalytic substrate 8, 9, thereby to provide a species active against the one or more predetermined reactants comprised within the feed 14. In a preferred embodiment, the transport medium is a waveguide. More preferably, the waveguide is discrete disc 10 spaced apart from other discrete discs so as to facilitate flow of the liquid feed 14 therebetween. Alternatively, the waveguide is a helical member 10 configured such that the feed 14 flows between successive winds of the helix. The waveguide may act both as the transport medium and as a substrate for catalytic material applied to the surface thereof. Preferably, the waveguide comprises a single material. Alternatively, the waveguide comprises a plurality of materials.

Preferably, the plurality of materials are of differing refractive indices, thereby to relatively enhance the waveguiding efficiency of the waveguide.

The waveguide may comprise scattering centres, reflective elements, diffractive elements, or a combination thereof, thereby to facilitate incident light being shifted out of the plane of the waveguide and contacting with the photocatalyst. The active species is most preferably the free radicals and electron holes in the TiO₂. The apparatus also comprises means for contacting said active species with said feed, thereby to actively effect said predetermined transformation. As such, the catalytic material is applied to one or more surfaces of the catalytic substrate, or to one or more surfaces of the discrete spacer unit/s (if used). Preferably, the catalytic material is illuminated substantially perpendicular to the axis thereof. Alternatively, the catalytic material may be illuminated substantially parallel to the axis thereof.

The catalytic material is provided as a coating over one or more surfaces of the waveguide, and/or over one or more surfaces of the spacer unit and/or over the interior surface 7 of the module housing/reaction vessel 1, itself defining the reaction chamber 17. Foreseeably, the coating is adhered to the waveguide/spacer/housing via solid phase, gas phase and/or liquid phase deposition techniques. Such deposition techniques comprise annealing, adhesive, etching, extrusion, moulding, dip coating, sputter coating, slot coating, lamination, or a combination thereof .

The coating may be on a substantially smooth or complex surface. Most preferably, the waveguide has a complex surface. The complex surface is applied upon the waveguide by etching, extrusion moulding, stamping, or a combination thereof. The complex surface serves as to increase the surface area of the photocatalyst, whilst at once enhancing fluid dymamics/mixing/flowthough within the apparatus.

In one embodiment, the complex surface is formed in the same material and is integral with the waveguide. Alternatively, the complex surface is formed separately from the waveguide. Preferably, the complex surface is formed in a different material to the waveguide. The complex surface facilitates enhanced fluid dynamics, such as relatively enhanced flow rate and/or relatively enhanced mixing. The complex surface also increases the effective surface area of the catalytic substrate. The feed 14 comprises said one or more predetermined reactants in aqueous phase. The contaminated or polluted liquid generally comprises one or more organic contaminants. More preferably, the one or more organic contaminants comprise organic molecules and/or organisms. More preferably still, the organic molecules comprise carcinogenic, endocrine-disrupting or unaesthetic compounds. The one or more organisms comprise bacteria, protozoa and/or viruses.

The waveguide unit may comprise one or more stacked discs. The arrangement of one or more stacked discs are spaced by one or more discrete spacer units and/or the complex surface. The one or more stacked discs are arranged to provide optimal contact time of the feed with the active species. Ideally, the one or more stacked discs are arranged to provide a relatively increased surface area per unit reactor fluid volume. The arrangement of one or more stacked discs are arranged to provide a disturbed flow of the feed between the discs to promote fluid mixing.

In a preferred embodiment comprising either the helix or the plurality of spaced discs, the diameter of a module is approximately 200 mm, the length around 1.2 m, the surface area of photocatalyst around 8 m² and where discs are used, the number of discs is around 300, each spaced around 0.5 mm apart. As such, the individual modules are able to be handled by individuals and placed in banks as per Figure 4 without undue difficulty. The banks of modules can be arranged such that the individual modules are able to function either in series or in parallel. When functioning in series, a feed will flow from one module to the next, receive substantially equivalent treatment (or even adjusted ratios of photolysis/photocatalysis in each module) before flowing into the next module. As such, each successive module decreases the level of contamination in the feed such that the end product may be potable water should enough modules be included in series. However, it will be appreciated that there are exponentially diminishing returns in subjecting the feed to each successive module. Re-oxygenation of the fluid within such a series may also be necessary to maintain the production of the reactive species generated in the photocatalysis reaction. Alternatively, when arranged in parallel, each module treats a discrete flow of feed substantially to completion or to within the required contaminant concentration limit. Whether modules are to be arranged in series or parallel depends upon factors including but not limited to: flow rate; residence time; contaminant composition, load, concentration; photocatalytic area; fluid oxygen concentration; and potable standard of end product likely to be required.

In a preferred embodiment, the relatively increased surface area of the photocatalyst is enabled by way of coating the interior surface of the module housing with TiO₂. As such, the surface area per unit volume ratio of increased with respect to the photocatalyst, and this arrangement also allows less of the waveguide to be coated in TiO₂, which itself, facilitates a relatively increased amount of photolysis.

The present invention provides a chemical reactor (filter) vessel that enables dissolved small organic compounds, e.g. 7V-nitrosodimethyleamine (NDMA) or 1,4- dioxane, in an aqueous gas or aqueous liquid feed to be destroyed or broken down by an advanced oxidation process (AOP), undertaken in a photocatalytic reaction. The reactor vessel enables UV light to be transmitted from a light source, to a waveguide, or series of waveguides optionally having a photocatalytic surface that enables the photocatalytic portion thereof to undergo photocatalysis, which in turn produces an AOP to destroy organics present in the gaseous or fluid feed, as it passes over the surface of the sheets.

In a particularly preferred embodiment, the photocatalytic surface is formed by etching, extruding, moulding, or any other known or applicable means. The photocatalytic surface may comprise a complex surface to allow an increase in surface area, whilst at once helping the fluid dynamics (i.e. flow, mixing) of the system. The complex surface may even function as the spacer, in which case the photocatalytic discs are self-stacking. In employing the method provided by the present invention, the photocatalytic surface is self-cleansing.

In terms of the comparative advantages of the configuration proposed according to the present invention, the most important consideration is cost per quantity of feed treated. Overall cost comprises initial capital expenditure plus ongoing operating and maintenance costs. Also important is the time and expenditure required to develop new water treatment technologies, which directly takes account of the degree to which earlier non-patented engineering technologies may be incorporated, both from photonics and membrane water treatment processes. Optical transporters such as those defined according to the present invention are readily available at relatively low cost. However, almost any optically clear extruded or molded polymer sheet could be used, such as an acrylic or cyclo-olefin copolymer.

The most preferred embodiments of the present invention are directed toward using a plurality of optical discs or a helical waveguide configuration. The principal advantages of such a system include optimising the energy efficiency in removing organic species by generating radicals and TiO₂ electron holes, in situ, ensuring relatively more of the light is converted to radicals, and ensuring that the radicals are most efficiently used to react with the small organic molecules, as opposed to recombining with each other.

A further advantage resides in the use of existing filter and membrane cartridge peripheral/support engineering technologies. This results in lower development and unit costs. It also allows a single or low count of UV lamp to illuminate an effectively large volume of water. .

Yet a further advantage of the present invention resides in it using existing cartridge designs, the ancillary engineering and maintenance and service procedures (pipes, pumps, valves, control systems, management software and hardware) will also be familiar and have relatively low cost. This engineering has a direct effect upon the volume-cost curve. Familiar engineering also lowers the barrier to adoption of this new technology within the marketplace.

Rather than the solid acrylic waveguides proposed thus far, referring now specifically to Figure 8, an alternative form of the inventive waveguide consists in an apparatus for delivering one or more active species to a reaction vessel, thereby to effect a predetermined chemical transformation. The apparatus comprises means for providing a feed to said reaction vessel, the feed comprising one or more predetermined chemical reactants; an energy source 5, thereby to produce incident energy therefrom; a transport medium communicable between the reaction vessel and the energy source, thereby to deliver the incident energy proximal with the one or more predetermined chemical reactants; and means for contacting the active species with said one or more predetermined chemical reactants, thereby to actively effect said predetermined chemical transformation to give a remediated product.

It will be appreciated that the transport medium is a waveguide 4, 10. The waveguide need not comprise a solid disc or helix as described in relation to Figures 5 and 6. Specifically, in this instance, the waveguide comprises two spaced sheets 18 defining a cavity 19 therebetween. The cavity is filled with any fluid medium 20, or mixture of fluid media that facilitate the propagation of the incident energy therethrough. As such, the fluid media must have an appropriate refractive index, or other physical properties such that the incident energy absorbed is minimised, deactivated or deflected elsewhere.

The waveguide 10 may be fitted with a lens and/or an anti-reflective element thereby to focus said energy in a predetermined manner. For example, incident energy that would otherwise travel along the waveguide without being directed into the reaction vessel in the required manner (i.e. light that would otherwise escape from the waveguide without contacting with the reactant) could be focussed by a lens, thereby to enter the reaction vessel in the required manner; or could be reflected back into the waveguide 6 for another pass in which it may be utilised as intended. To this end, the lens/reflective element embodiment is useful in optimising the amount of energy that is ultimately used to effect said transformation. This has attendant cost advantages in terms of increased efficiency.

The cavity 20 may comprise one or more gases, and/or one or more fluid materials. Foreseeable media through which the incident energy can propagate include air, mineral oil/s, water or fluorinated siloxanes. The incident energy comprises the active species. Specifically, in this embodiment, the incident energy is UV light of between approximately 200 and 400 nm wavelength. Optionally, the energy source is associated with a catalytic substrate, thereby to actively convert the incident energy to said one or more active species. In this case, the catalytic substrate is again TiO₂. In an embodiment, the TiO₂ is present as a secondary laminate coating at least part of one or more surfaces of the waveguide. Preferably, the TiO₂ is of a uniform or non-uniform thickness of up to 20 microns; preferably, about 0.1 to 15 microns; most preferably, about 0.1 to 5 microns. Alternatively, if not comprising a catalytic substrate, the secondary laminate renders advantageous mechanical strength characteristics by way of reinforcing the rigidity of the waveguide.

The association of the catalytic substrate with the waveguide is alternatively such that the catalytic substrate is suspended within the waveguide. Alternatively, the catalytic substrate is dispersed within the feed of contaminated fluid undergoing remediation. However, in this latter case, any such method would necessarily comprise the further step of retrieving and/or recycling the catalytic substrate from the remediated product.

In an embodiment, the waveguide is constructed of a plurality of materials of different refractive indices, thereby to relatively optimise the waveguiding efficiency of the waveguide, relative to the predetermined chemical reaction being undertaken. The waveguide may comprise scattering centres, reflective elements, diffractive elements, or a combination thereof, thereby to facilitate the incident energy being shifted out of the plane of the waveguide, thereby to contact with the one or more predetermined chemical reactants. In an embodiment, the feed may also be "doped" with one or more other active species prior to introduction into the apparatus, or performing the method according to the present invention. For example, the raw feed may be doped with chlorine, a chlorine-containing compound, a chlorine-derived compound, ozone, peroxide or a species comprising active oxygen "upstream" of the reaction vessel. The one or more dopants may be active to perform a corresponding one or more reactions either in synergy with, or independently of the active species delivered according to the method and apparatus of the present invention. To this end, the inventive apparatus may be modified to provide means for providing such a dopant.

The waveguide may also comprise a mirrored or reflective surface 21 therewithin. This has the effect such that any incident energy that is not deflected into the reaction vessel on a first pass is reflected back into the waveguide whereby it may be scattered on a subsequent pass. Accordingly, the present invention is relatively energy-efficient.

Referring now specifically to the embodiment depicted in Figure 9, which represents a side schematic view of a modified waveguide/spacer unit according to a preferred embodiment of the present invention, UV light propagates along and is scattered out of an uncoated acrylic waveguide 22. The incident UV then propagates through the feed flow 14 whereupon it performs UV photolysis upon certain organic molecules (such as NDMA) and any pathogens/micro-organisms present within the feed. UV that is not employed for photolysis or absorbed into the water propagates through the feed and contacts with the photocatalytic surface/s 9. UV transmitted through the approximate 10 micron TiO₂ thickness is then reflected back into the reaction vessel 1. UV contacting with the photocatalytic surface 9 be it on the first or subsequent pass, is catalysed to an excited species that creates radicals in water, thereby to effect decomposition of any organic load present in the feed and/or inactivate any pathogens/micro-organisms in the feed.

In summary, a system according to the present invention should have significant cost advantages. For a specific required removal rate of small organic molecules in Reverse Osmosis effluent, lower investment cost should be achieved, together with relatively reduced operating and maintenance costs.

In general terms, the present invention is advantageous in that it creates an efficient means to bring a reaction system together with activating light in a low cost cartridge, with the ability to adjust the relative surface areas and volumes with relative ease, in order to maximise the efficiency of the process.

One foreseeable application of the inventive system is for water treatment to remove dissolved organics. However, it would be readily apparent to one skilled in the relevant art that the system may have efficacy for any fluid reaction system where photocatalysis and/or photolysis is required. Moreover, the means in which the photocatalyst is employed is optional; it can be placed on the surface of the optical transporter, as described, or even in suspension. The effluent phase can be a liquid or a gas. The light source can be any wavelength of light that is suitable to induce photocatalysis.

As used throughout the specification and claims, the term "waveguide" should be taken to mean a structure that is applied to transport incident energy from the energy source to the one or more predetermined chemical reactants. Thusly, in the context of the present invention, the transport medium comprising, for example, one or more plastic sheets is taken to be the waveguide. In other preferred embodiments of the invention, the waveguide is defined by the channel between two or more stacked plates (including he plates themselves). It will be appreciated that other interchangeable terms of the art may include "light box", "optical transporter", or "transport medium".

Reference throughout this specification to "one embodiment" or "an embodiment" means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrases "in one embodiment" or "in an embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment, but may. Furthermore, the particular features, structures or characteristics may be combined in any suitable manner, as would be apparent to one of ordinary skill in the art from this disclosure, in one or more embodiments.

Similarly it should be appreciated that in the above description of exemplary embodiments of the invention, various features of the invention are sometimes grouped together in a single embodiment, FIG., or description thereof for the purpose of streamlining the disclosure and aiding in the understanding of one or more of the various inventive aspects. This method of disclosure, however, is not to be interpreted as reflecting an intention that the claimed invention requires more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive aspects lie in less than all features of a single foregoing disclosed embodiment. Thus, the claims following the Detailed Description are hereby expressly incorporated into this Detailed Description, with each claim standing on its own as a separate embodiment of this invention.

Furthermore, while some embodiments described herein include some but not other features included in other embodiments, combinations of features of different embodiments are meant to be within the scope of the invention, and form different embodiments, as would be understood by those in the art. For example, in the following claims, any of the claimed embodiments can be used in any combination.

Furthermore, some of the embodiments are described herein as a method or combination of elements of a method that can be implemented by a processor of a computer system or by other means of carrying out the function. Thus, a processor with the necessary instructions for carrying out such a method or element of a method forms a means for carrying out the method or element of a method. Furthermore, an element described herein of an apparatus embodiment is an example of a means for carrying out the function performed by the element for the purpose of carrying out the invention.

In the description provided herein, numerous specific details are set forth. However, it is understood that embodiments of the invention may be practiced without these specific details. In other instances, well-known methods, structures and techniques have not been shown in detail in order not to obscure an understanding of this description.

As used herein, unless otherwise specified the use of the ordinal adjectives "first", "second", "third", etc., to describe a common object, merely indicate that different instances of like objects are being referred to, and are not intended to imply that the objects so described must be in a given sequence, either temporally, spatially, in ranking, or in any other manner.

In the claims below and the description herein, any one of the terms comprising, comprised of or which comprises is an open term that means including at least the elements/features that follow, but not excluding others. Thus, the term comprising, when used in the claims, should not be interpreted as being limitative to the means or elements or steps listed thereafter. For example, the scope of the expression a device comprising A and B should not be limited to devices consisting only of elements A and B. Any one of the terms including or which includes or that includes as used herein is also an open term that also means including at least the elements/features that follow the term, but not excluding others. Thus, including is synonymous with and means comprising.

Thus, while there has been described what are believed to be the preferred embodiments of the invention, those skilled in the art will recognise that other and further modifications may be made thereto without departing from the spirit of the invention, and it is intended to claim all such changes and modifications as fall within the scope of the invention. For example, any formulas given above are merely representative of procedures that may be used. Functionality may be added or deleted from the block diagrams and operations may be interchanged among functional blocks. Steps may be added or deleted to methods described within the scope of the present invention.

Unless the context clearly requires otherwise, throughout the description and the claims, the words 'comprise', 'comprising', and the like are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense; that is to say, in the sense of "including, but not limited to".

Although the invention has been described with reference to specific examples it will be appreciated by those skilled in the art that the invention may be embodied in many other forms.

Claims

THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS:-

1. A method for effecting transformation of a reactant species in a reaction vessel, said method comprising the steps of: providing a catalytic substrate; providing a feed comprising said reactant species; providing an energy source wherein energy derived therefrom is contactable via a transport medium with said catalytic substrate, thereby to provide a species active against said reactant species; and contacting said active species with said reactant species, thereby to actively effect said transformation.

2. A method for creating one or more active species in a reaction vessel, thereby to effect transformation of a reactant species, said method comprising the steps of: providing a feed to said reaction vessel, said feed comprising one or more reactant species; providing an energy source, thereby to produce incident energy therefrom; providing a transport medium communicable between said reaction vessel and said energy source to deliver said incident energy to said one or more reactant species, thereby to actively effect said transformation.

3. A method according to claim 1 or claim 2, wherein said transport medium is fluid.

4. A method according to any one of the preceding claims, wherein said transport medium is a waveguide.

5. A method according to claim 4, wherein said waveguide is an optical waveguide.

6. A method according to claim 4 or claim 5, wherein said waveguide acts both as said transport medium and as a substrate for catalytic material applied to the surface thereof.

7. A method according to claim 6, wherein said waveguide is adapted to act either as said transport medium and/or as a substrate for said catalytic material and/or as a fluid flow channel defining means.

8. A method according to any one of claims 4 to 7, wherein said waveguide comprises a single material.

9. A method according to any one of claims 4 to 8, wherein said waveguide comprises a plurality of materials.

10. A method according to claim 9, wherein said plurality of materials are of differing refractive indices, thereby to relatively enhance the waveguiding efficiency of said waveguide.

11. A method according to any one of claims 4 to 10, wherein said waveguide may comprise, at its surface or in the bulk of its material, scattering centres, reflective elements, diffractive elements, areas of differing thicknesses, or a combination thereof, thereby to facilitate incident light being shifted out of the plane of said waveguide.

12. A method according to any one of claims 4 to 1 1, wherein said waveguide comprises a disc.

13. A method according to claim 12, wherein said disc is substantially UV- transparent.

14. A method according to claim 12 or claim 13, wherein said disc is formed of a plastics material capable of appreciably transmitting ultra-violet light.

15. A method according to claim 13 or claim 14, wherein said substantially UV- transparent disc is quartz or polymer.

16. A method according to any one of claims 4 to 15, wherein said waveguide comprises a plurality of discs, thereby to define a module.

17. A method according to claim 16, wherein said plurality of discs are spaced apart by discrete spacer units.

18. A method according to claim 17, wherein each said disc has a hole substantially at the centre thereof.

19. A method according to claim 18, wherein said plurality of discs are configured such that each said hole aligns to define a central channel.

20. A method according to claim 19, wherein said central channel is adapted to house said energy source.

21. A method according to claim 20, wherein said energy source is configured to extend substantially along the length of said channel.

22. A method according to any one of claims 4 to 21 , wherein said waveguide is configured to provide a relatively increased surface area per unit reactor fluid volume.

23. A method according to any one of claims 16 to 22, wherein said plurality of discs numbers of the order 10².

24. A method according to any one of claims 16 to 23, wherein said plurality of discs numbers substantially 300.

25. A method according to any one of claims 16 to 24, wherein said plurality of discs have a surface area of substantially 8 m².

26. A method according to any one of claims 16 to 25, wherein said plurality of discs each have a surface area substantially of the order 10^"' m².

27. A method according to any one of claims 19 to 26, wherein said channel is approximately 1.2 m in length.

28. A method according to any one of claims 17 to 27, wherein said discrete spacer units hold adjacent discs between substantially 0.1 and 0.5 mm apart.

29. A method according to any one of claims 17 to 28, wherein said discrete spacer units hold adjacent discs substantially 0.1 mm apart.

30. A method according to claim 1, wherein said catalytic substrate is a photocatalytic substrate.

31. A method according to claim 30, wherein said photocatalytic substrate is selected from the group consisting of: TiO₂, zinc oxide (ZnO), CdS and tungsten oxide (WO₃).

32. A method according to claim 30 or claim 31, wherein said photocatalytic substrate is TiO₂.

33. A method according to any one of the preceding claims, wherein said energy is

UV light derived from a UV source.

34. A method according to claim 33, wherein said UV source is a tube or an LED.

35. A method according to claim 33, wherein said UV source is sunlight, said sunlight being piped into the reactor volume using a light pipe, wherein the incident sunlight is first collected using a solar collector.

36. A method according to any one of claims 33 to 35, wherein said UV source is focused on the outside of the module.

37. A method according to any one of claims 33 to 36, wherein said UV source is protected from said fluid by using a substantially UV-transparent tubing.

38. A method according to claim 37, wherein said UV source and/or said UV- transparent tubing comprises anti-reflective coatings or structure, thereby to prevent UV being reflected back into said UV source and being wasted.

39. A method according to any one of the preceding claims, wherein said energy source is a UV lamp.

40. A method according to claim 39, wherein said UV lamp is of substantially 15 W in power.

41. A method according to any one of claims 33 to 40, wherein said light comprises one or more wavelengths within the range of approximately 200-400 nm.

42. A method according to claim 1, wherein said active species is an excited species.

43. A method according to claim 42, wherein said excited species are free radicals and TiO₂ electron holes.

44. A method according to any one of claims 6 to 43, wherein said catalytic material is provided as a coating over one or more surfaces of said waveguide.

45. A method according to claim 44, wherein said coating is adhered to said waveguide via solid phase, gas phase and/or liquid phase deposition techniques.

46. A method according to claim 45, wherein said deposition techniques comprise chemical grafting, annealing, adhesive, etching, extrusion, moulding, dip coating, sputter coating, slot coating, lamination, or a combination thereof.

47. A method according to any one of the preceding claims, wherein said feed is a fluid.

48. A method according to claim 47, wherein said fluid is a liquid, gas, or a combination thereof.

49. A method according to claim 47 or claim 48, wherein said fluid is a fluid effluent, said method thereby operative to treat at least a portion of said fluid effluent.

50. A method according to claim 49, wherein said fluid effluent is a contaminated or polluted liquid, gas and/or steam.

51. A method according to claim 50, wherein said liquid, gas and/or steam comprises said one or more predetermined reactant species in solution state.

52. A method according to claim 50 or claim 51, wherein said liquid is water.

53. A method according to claim 51 or claim 52, wherein said solution comprises said one or more predetermined reactant species in aqueous phase.

54. A method according to any one of claims 50 to 53, wherein said contaminated or polluted liquid comprises one or more organic contaminants.

55. A method according to any one of claims 47 to 54, wherein said fluid is chemical.

56. A method according to claim 55, wherein said chemical is a chemical solvent, wherein a predetermined photocatalytic reaction is used as part of a synthetic route.

57. A method according to any one of claims 47 to 56, wherein said fluid is wet gas from a combustion engine or other, said method thereby effective to relatively reduce emissions from said engine.

58. A method according to claim 57, further comprising a catalyst selected from the group consisting of: TiO₂, zinc oxide (ZnO), CdS and tungsten oxide (WO₃).

59. A method according to any one of claims 54 to 58, wherein said one or more organic contaminants comprise organic molecules and organisms.

60. A method according to claim 59, wherein said one or more organisms comprise bacteria, protozoa and/or viruses.

61. A method according to claim 60, wherein said organic molecules comprise carcinogenic, endocrine-disrupting and/or unaesthetic compounds.

62. A method according to claim 61, wherein said carcinogenic, endocrine- disrupting and/or unaesthetic compounds comprise 1,4-dioxane and/or N- nitrosodimethylamine (NDMA).

63. A method according to any one of the preceding claims, further including provision of an outlet port remote from an inlet port, thereby to facilitate flow of said feed therebetween.

64. A method according to any one of claims 1 to 62, further including provision of an outlet port integral with an inlet port, thereby to facilitate said method to operate on a batch basis.

65. A method according to any one of claims 4 to 64, wherein said waveguide is configurable so as to optimise the proportion of said active species or said incident energy relative to the composition of said feed.

66. A method according to any one of the preceding claims, wherein said transformation is effected by photocatalysis and/or photolysis.

67. A method according to claim 66, wherein said photocatalysis is effected from incident light interacting with a TiO₂ coating upon one or more surfaces of said waveguide.

68. A method according to claim 66 or claim 67, wherein said photolysis is effected from incident light passing through one or more uncoated surfaces of said waveguide.

69. A method according to any one of claims 4 to 68, wherein said waveguide comprises one or more continuous helical elements, arranged coincident or spaced apart, thereby to provide a manifold of flow channels.

70. A method according to claim 69, wherein said continuous helix is a discrete repeating unit.

71. A method according to claim 69, wherein said continuous helix comprises a plurality of adjoined units.

72. A method according to any one of claims 69 to 71, wherein successive winds of said helix are spaced by one or more discrete spacer units.

73. A method according to claim 2, wherein said incident energy is a species active against said one or more predetermined reactant species.

74. A method according to claim 1, wherein the association of said catalytic substrate with said transport medium is such that said catalytic substrate is coated over at least part of one or more surfaces of said transport medium.

75. A method according to claim 1 , wherein titanium dioxide is coated upon one or more surfaces of said catalytic substrate to a uniform or non-uniform thickness of up to approximately 20 microns.

76. A method according to claim 75, wherein titanium dioxide is coated upon one or more surfaces of said catalytic substrate to a uniform or non-uniform thickness of about 0.1 to 15 microns.

77. A method according to claim 75 or claim 76, wherein titanium dioxide is coated upon one or more surfaces of said catalytic substrate to a uniform or nonuniform thickness of about 0.1 to 5 microns.

78. A method according to any one of claims 4 to 77, wherein said waveguide is configured to provide optimal contact time of said feed with said active species.

79. A method according to any one of the preceding claims, wherein said transformation takes place within a modular apparatus.

80. A method according to claim 1, wherein said energy source is spaced from or proximal with said catalytic substrate.

81. A method according to claim 1, wherein said energy source is directly coupled with said catalytic substrate.

82. A method according to claim 1, wherein said catalytic substrate is applied to one or more auxiliary surfaces spaced from said transport medium to define a reactor volume comprising said one or more reactant species, said incident energy thereby able to perform a photolytic transformation prior to contacting with said photocatalytic surface following which a photocatalytic transformation may be effected.

83. A method according to claim 82, wherein said one or more auxiliary surfaces is substantially reflective such that energy passing through said catalytic surface is reflected back toward said reactor volume.

84. A method according to claim 82 or claim 83, wherein said one or more auxiliary surfaces is substantially transmissive such that energy passing through said catalytic surface is directed toward a further reactor volume.

85. A method according to any one of the preceding claims, further comprising the step of adding one or more predetermined additive to said feed prior to introducing said feed to said active species.

86. A method according to claim 85, wherein said additive is selected from the group consisting of: chlorine, a chlorine-containing additive, a chlorine-derived additive, hydrogen peroxide, ozone and additive comprising active oxygen.

87. A method according to claim 86, wherein said additive is chlorine, a chlorine- containing or a chlorine-derived additive.

88. A method according to any one of claims 4 to 87, wherein said waveguide comprises a lens, thereby to focus said energy in a predetermined manner.

89. A method according to any one of claims 4 to 88, wherein said waveguide comprises a reflecting element, thereby to redirect said energy in a predetermined manner.

90. A method according to claim 3, wherein said fluid transport medium is a waveguide.

91. A method according to claim 90, wherein said fluid waveguide is a liquid waveguide.

92. A method according to claim 91, wherein said liquid waveguide comprises water.

93. A method according to claim 92, wherein said water is contaminated water.

94. A method according to claim 1, wherein said energy source is proximal with said catalytic substrate, thereby to selectively control the pathlength therebetween.

95. A method according to claim 94, wherein the proximity of said energy source to said catalytic substrate is such that energy derived from said energy source is not significantly dissipated within said fluid transport medium prior to contacting with said one or more reactant species.

96. A method according to any one of claims 90 to 95, wherein said reaction vessel is provided with interior functionality, thereby to relatively increase the interior surface area and/or provide manipulable flow characteristics within said reaction vessel or said apparatus.

97. A method according to claim 96, wherein said interior functionality is selected from the group consisting of: one or more discrete discs, one or more discrete or adjoined helical elements, one or more nodules, one or more complex surfaces, and combinations thereof.

98. A method according to claim 96 or claim 97, wherein said interior functionality provides a complementary or synergistic transport medium to said fluid transport medium.

99. A method according to claim 96 or claim 97, wherein said interior functionality is not adapted to provides a complementary or synergistic transport medium to said fluid transport medium.

100. The product of a transformed reactant species in a reaction vessel, when said product is so-effected by a method according to claim 1.

101. One or more active species created in a reaction vessel, when so-created by a method according to claim 2.

102. An apparatus for effecting transformation of a reactant species, said apparatus comprising: a catalytic substrate; means for providing a feed comprising one or more said reactant species; an energy source; a transport medium through which energy derived from said energy source is contactable with said catalytic substrate, thereby to provide a species active against said one or more reactant species; and means for contacting said active species with said reactant species, thereby to actively effect said transformation.

103. An apparatus for creating one or more active species in a reaction vessel, thereby to effect transformation of a reactant species, said apparatus comprising: means for providing a feed to said reaction vessel, said feed comprising one or more reactant species; an energy source, thereby to produce incident energy therefrom; a transport medium communicable between said reaction vessel and said energy source, thereby to deliver said incident energy proximal with said one or more reactant species; and means for contacting said incident energy with said one or more reactant species, thereby to actively effect said transformation.

104. An apparatus according to claim 102 or claim 103, wherein said transport medium is fluid.

105. An apparatus according to any one claims 101 to 104, wherein said transport medium is a waveguide.

106. An apparatus according to claim 105, wherein said waveguide is an optical waveguide.

107. An apparatus according to claim 105 or claim 106, wherein said waveguide acts both as said transport medium and as a substrate for catalytic material applied to the surface thereof.

108. An apparatus according to claim 107, wherein said waveguide is adapted to act either as said transport medium and/or as a substrate for said catalytic material and/or as a fluid flow channel defining means.

109. An apparatus according to any one of claims 105 to 108, wherein said waveguide comprises a single material.

110. An apparatus according to any one of claims 105 to 109, wherein said waveguide comprises a plurality of materials.

1 1 1. An apparatus according to claim 110, wherein said plurality of materials are of differing refractive indices, thereby to relatively enhance the waveguiding efficiency of said waveguide.

112. An apparatus according to any one of claims 105 to 111, wherein said waveguide may comprise, at its surface or in the bulk of its material, scattering centres, reflective elements, diffractive elements, areas of differing thicknesses, or a combination thereof, thereby to facilitate incident light being shifted out of the plane of said waveguide.

113. An apparatus according to any one of claims 105 to 112, wherein said waveguide comprises a disc.

114. An apparatus according to claim 113, wherein said disc is substantially UV- transparent.

115. An apparatus according to claim 1 13 or claim 114, wherein said disc is formed of a plastics material capable of appreciably transmitting ultra-violet light.

1 16. An apparatus according to claim 1 14 or claim 1 15, wherein said substantially UV -transparent disc is quartz or polymer.

1 17. An apparatus according to any one of claims 105 to 1 16, wherein said waveguide comprises a plurality of discs, thereby to define a module.

1 18. An apparatus according to claim 1 17, wherein said plurality of discs are spaced apart by discrete spacer units.

1 19. An apparatus according to claim 1 18, wherein each said disc has a hole substantially at the centre thereof.

120. An apparatus according to claim 1 19, wherein said plurality of discs are configured such that each said hole aligns to define a central channel.

121. An apparatus according to claim 120, wherein said central channel is adapted to house said energy source.

122. An apparatus according to claim 121, wherein said energy source is configured to extend substantially along the length of said channel.

123. An apparatus according to any one of claims 105 to 122, wherein said waveguide is configured to provide a relatively increased surface area per unit reactor fluid volume.

124. An apparatus according to any one of claims 117 to 123, wherein said plurality of discs numbers of the order 10².

125. An apparatus according to any one of claims 117 to 124, wherein said plurality of discs numbers substantially 300.

126. An apparatus according to any one of claims 117 to 125, wherein said plurality of discs have a surface area of substantially 8 m².

127. An apparatus according to any one of claims 1 17 to 126, wherein said plurality of discs each have a surface area substantially of the order 10^'1 m².

128. An apparatus according to any one of claims 120 to 127, wherein said channel is approximately 1.2 m in length.

129. An apparatus according to any one of claims 1 18 to 128, wherein said discrete spacer units hold adjacent discs between substantially 0.1 and 0.5 mm apart.

130. An apparatus according to any one of claims 1 18 to 129, wherein said discrete spacer units hold adjacent discs substantially 0.1 mm apart.

131. An apparatus according to claim 102, wherein said catalytic substrate is a photocatalytic substrate.

132. An apparatus according to claim 131, wherein said photocatalytic substrate is selected from the group consisting of: TiO₂, zinc oxide (ZnO), CdS and tungsten oxide (WO₃).

133. An apparatus according to claim 131 or claim 132, wherein said photocatalytic substrate is TiO₂.

134. An apparatus according to any one of claims 102 to 133, wherein said energy is UV light derived from a UV source.

135. An apparatus according to claim 134, wherein said UV source is a tube or an LED.

136. An apparatus according to claim 134, wherein said UV source is sunlight, said sunlight being piped into the reactor volume using a light pipe, wherein the incident sunlight is first collected using a solar collector.

137. An apparatus according to any one of claims 134 to 136, wherein said UV source is focused on the outside of the module.

138. An apparatus according to any one of claims 134 to 137, wherein said UV source is protected from said fluid by using a substantially UV-transparent tubing.

139. An apparatus according to claim 138, wherein said UV source and/or said UV- transparent tubing comprises anti-reflective coatings or structure, thereby to prevent UV being reflected back into said UV source and being wasted.

140. An apparatus according to any one of claims 102 to 139, wherein said energy source is a UV lamp.

141. An apparatus according to claim 140, wherein said UV lamp is of substantially 15 W in power.

142. An apparatus according to any one of claims 134 to 141, wherein said light comprises one or more wavelengths within the range of approximately 200-400 nm.

143. An apparatus according to claim 102, wherein said active species is an excited species.

144. An apparatus according to claim 143, wherein said excited species are free radicals and TiO₂ electron holes.

145. An apparatus according to any one of claims 107 to 144, wherein said catalytic material is provided as a coating over one or more surfaces of said waveguide.

146. An apparatus according to claim 145, wherein said coating is adhered to said waveguide via solid phase, gas phase and/or liquid phase deposition techniques.

147. An apparatus according to claim 146, wherein said deposition techniques comprise chemical grafting, annealing, adhesive, etching, extrusion, moulding, dip coating, sputter coating, slot coating, lamination, or a combination thereof.

148. An apparatus according to any one of claims 102 to 147, wherein said feed is a fluid.

149. An apparatus according to claim 148, wherein said fluid is a liquid, gas, or a combination thereof.

150. An apparatus according to claim 148 or claim 149, wherein said fluid is a fluid effluent, said method thereby operative to treat at least a portion of said fluid effluent.

151. An apparatus according to claim 150, wherein said fluid effluent is a contaminated or polluted liquid, gas and/or steam.

152. An apparatus according to claim 151 , wherein said liquid, gas and/or steam comprises said one or more predetermined reactant species in solution state.

153. An apparatus according to claim 151 or claim 152, wherein said liquid is water.

154. An apparatus according to claim 152 or claim 153, wherein said solution comprises said one or more predetermined reactant species in aqueous phase.

155. An apparatus according to any one of claims 151 to 154, wherein said contaminated or polluted liquid comprises one or more organic contaminants.

156. An apparatus according to any one of claims 148 to 155, wherein said fluid is chemical.

157. An apparatus according to claim 156, wherein said chemical is a chemical solvent, wherein a predetermined photocatalytic reaction is used as part of a synthetic route.

158. An apparatus according to any one of claims 148 to 157, wherein said fluid is wet gas from a combustion engine or other, said method thereby effective to relatively reduce emissions from said engine.

159. An apparatus according to claim 158, further comprising a catalyst selected from the group consisting of: TiO₂, zinc oxide (ZnO), CdS and tungsten oxide (WO₃).

160. An apparatus according to any one of claims 155 to 159, wherein said one or more organic contaminants comprise organic molecules and organisms.

161. An apparatus according to claim 160, wherein said one or more organisms comprise bacteria, protozoa and/or viruses.

162. An apparatus according to claim 161, wherein said organic molecules comprise carcinogenic, endocrine-disrupting and/or unaesthetic compounds.

163. An apparatus according to claim 162, wherein said carcinogenic, endocrine- disrupting and/or unaesthetic compounds comprise 1 ,4-dioxane and/or N- nitrosodimethylamine (NDMA).

164. An apparatus according to any one of claims 102 to 163, further including provision of an outlet port remote from an inlet port, thereby to facilitate flow of said feed therebetween.

165. An apparatus according to any one of claims 102 to 163, further including provision of an outlet port integral with an inlet port, thereby to facilitate said method to operate on a batch basis.

166. An apparatus according to any one of claims 105 to 165, wherein said waveguide is configurable so as to optimise the proportion of said active species or said incident energy relative to the composition of said feed.

167. An apparatus according to any one of claims 102 to 166, wherein said transformation is effected by photocatalysis and/or photolysis.

168. An apparatus according to claim 167, wherein said photocatalysis is effected from incident light interacting with a TiO₂ coating upon one or more surfaces of said waveguide.

169. An apparatus according to claim 167 or claim 168, wherein said photolysis is effected from incident light passing through one or more uncoated surfaces of said waveguide.

170. An apparatus according to any one of claims 105 to 169, wherein said waveguide comprises one or more continuous helical elements, arranged coincident or spaced apart, thereby to provide a manifold of flow channels.

171. An apparatus according to claim 170, wherein said continuous helix is a discrete repeating unit.

172. An apparatus according to claim 170, wherein said continuous helix comprises a plurality of adjoined units.

173. An apparatus according to any one of claims 170 to 172, wherein successive winds of said helix are spaced by one or more discrete spacer units.

174. An apparatus according to claim 103, wherein said incident energy is a species active against said one or more predetermined reactant species.

175. An apparatus according to claim 102, wherein the association of said catalytic substrate with said transport medium is such that said catalytic substrate is coated over at least part of one or more surfaces of said transport medium.

176. An apparatus according to claim 102, wherein titanium dioxide is coated upon one or more surfaces of said catalytic substrate to a uniform or non-uniform thickness of up to approximately 20 microns.

177. An apparatus according to claim 176, wherein titanium dioxide is coated upon one or more surfaces of said catalytic substrate to a uniform or non-uniform thickness of about 0.1 to 15 microns.

178. An apparatus according to claim 176 or claim 177, wherein titanium dioxide is coated upon one or more surfaces of said catalytic substrate to a uniform or nonuniform thickness of about 0.1 to 5 microns.

179. An apparatus according to any one of claims 105 to 178, wherein said waveguide is configured to provide optimal contact time of said feed with said active species.

180. An apparatus according to any one of claims 102 to 179, wherein said transformation takes place within a modular apparatus.

181. An apparatus according to claim 102, wherein said energy source is spaced from or proximal with said catalytic substrate.

182. An apparatus according to claim 102, wherein said energy source is directly coupled with said catalytic substrate.

183. An apparatus according to claim 102, wherein said catalytic substrate is applied to one or more auxiliary surfaces spaced from said transport medium to define a reactor volume comprising said one or more reactant species, said incident energy thereby able to perform a photolytic transformation prior to contacting with said photocatalytic surface following which a photocatalytic transformation may be effected.

184. An apparatus according to claim 183, wherein said one or more auxiliary surfaces is substantially reflective such that energy passing through said catalytic surface is reflected back toward said reactor volume.

185. An apparatus according to claim 183 or claim 184, wherein said one or more auxiliary surfaces is substantially transmissive such that energy passing through said catalytic surface is directed toward a further reactor volume.

186. An apparatus according to any one of claims 102 to 185, further comprising the step of adding one or more predetermined additive to said feed prior to introducing said feed to said active species.

187. An apparatus according to claim 186, wherein said additive is selected from the group consisting of: chlorine, a chlorine-containing additive, a chlorine-derived additive, hydrogen peroxide, ozone and additive comprising active oxygen.

188. An apparatus according to claim 187, wherein said additive is chlorine, a chlorine-containing or a chlorine-derived additive.

189. An apparatus according to any one of claims 105 to 188, wherein said waveguide comprises a lens, thereby to focus said energy in a predetermined manner.

190. An apparatus according to any one of claims 105 to 189, wherein said waveguide comprises a reflecting element, thereby to redirect said energy in a predetermined manner.

191. An apparatus according to claim 104, wherein said fluid transport medium is a waveguide.

192. An apparatus according to claim 191, wherein said fluid waveguide is a liquid waveguide.

193. An apparatus according to claim 192, wherein said liquid waveguide comprises water.

194. An apparatus according to claim 193, wherein said water is contaminated water.

195. An apparatus according to claim 102, wherein said energy source is proximal with said catalytic substrate, thereby to selectively control the pathlength therebetween.

196. An apparatus according to claim 195, wherein the proximity of said energy source to said catalytic substrate is such that energy derived from said energy source is not significantly dissipated within said fluid transport medium prior to contacting with said one or more reactant species.

197. An apparatus according to any one of claims 191 to 196, wherein said reaction vessel is provided with interior functionality, thereby to relatively increase the interior surface area and/or provide manipulable flow characteristics within said reaction vessel or said apparatus.

198. An apparatus according to claim 198, wherein said interior functionality is selected from the group consisting of: one or more discrete discs, one or more discrete or adjoined helical elements, one or more nodules, one or more complex surfaces, and combinations thereof.

199. An apparatus according to claim 197 or claim 198, wherein said interior functionality provides a complementary or synergistic transport medium to said fluid transport medium.

200. An apparatus according to claim 197 or claim 198, wherein said interior functionality is not adapted to provides a complementary or synergistic transport medium to said fluid transport medium.

201. A method for effecting transformation of a reactant species in a reaction vessel, said method substantially as herein described with reference to any one of the embodiments of the invention illustrated in the accompanying drawings and/or examples.

202. A method for creating one or more active species in a reaction vessel, thereby to effect transformation of a reactant species, said method substantially as herein described with reference to any one of the embodiments of the invention illustrated in the accompanying drawings and/or examples.

203. The product of a transformed reactant species in a reaction vessel, when said product is so-effected by a method substantially as herein described with reference to any one of the embodiments of the invention illustrated in the accompanying drawings and/or examples.

204. One or more active species created in a reaction vessel, when so-created by a method substantially as herein described with reference to any one of the embodiments of the invention illustrated in the accompanying drawings and/or examples.

205. An apparatus for effecting transformation of a reactant species, said apparatus substantially as herein described with reference to any one of the embodiments of the invention illustrated in the accompanying drawings and/or examples.

206. An apparatus for creating one or more active species in a reaction vessel, thereby to effect transformation of a reactant species, said apparatus substantially as herein described with reference to any one of the embodiments of the invention illustrated in the accompanying drawings and/or examples.