AU2023211210A1

AU2023211210A1 - Remediation of Water Pipelines

Info

Publication number: AU2023211210A1
Application number: AU2023211210A
Authority: AU
Inventors: Simon Bayley
Original assignee: Grenof Pty Ltd
Current assignee: Grenof Pty Ltd
Priority date: 2022-06-26
Filing date: 2023-08-07
Publication date: 2024-01-18

Abstract

A method for remediation of one or more water pipelines by circulating water through: a water treatment plant, an ozone unit, the one or more pipelines to be remediated, and back to water treatment plant, such that the one or more pipelines are cleaned and disinfected and water is regenerated and conserved. 04 C,4 04 CY) CN m CN C) C) C) (N 161 00 0) C) t__ C) C:) -------------------------------- 00 C.0 LO CN m LO (D"L* LO AN Lo 0-, co LO LO LO 4--a LO U) OD CN cr- C:) o CO C.0 C) Cl) LO 04 C) (0 CO n Cl) 0') co v C.0 Cl) ce) co C) co LO/l/ co Cl) 001 C) 04 CN co 04 co C) co C) 00 LO 04C) C) C) C) 04 CD CN CN C) 04 LO 2 C) co 04 CN IAI C:) C.0 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - C:) 04 C) FIG. 1

Description

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FIG. 1

AUSTRALIA

PATENTSACT1990

COMPLETE SPECIFICATION REMEDIATION OF WATER PIPELINES REMEDIATION OF WATER PIPELINES TECHNICAL FIELD

The invention relates to systems and methods for remediation of water pipelines. In particular, the invention relates to systems and methods for remediation of water pipelines that conserve water.

BACKGROUND OF THE INVENTION

It is to be understood that if any prior art publication is referred to herein, such reference does not constitute an admission that the publication forms a part of the common general knowledge in the art in Australia or any other country.

Of all municipal services, provision of potable water is perhaps the most vital. People depend on water for drinking, cooking, washing, carrying away wastes, and other domestic needs. Water supply systems must also meet requirements for public, commercial, and industrial activities. In all cases, the water must fulfil both quality and quantity requirements (Nathanson).

Drinking water systems or networks are designed to supply water to consumers in towns and cities in such a way to ensure it is delivered at a sufficient quality to meet the drinking water guidelines for that region, state, territory or nation.

The Australian Drinking Water Guidelines (ADWG) provide guidance for water providers to set their own specifications for potable water quality. These requirements are usually and generally adopted nationally as the standard for water quality and cover a range of parameters important for the delivery of high-quality drinking water from reticulated systems including: Free Chlorine; Turbidity; pH; Colour; Heterotrophic Plate Count (HPC); E. Coli (as a faecal contamination indicator); and, Total Coliform Count (TCC).

The management of drinking water quality requires a comprehensive system of regular testing, maintenance programs to keep the network operating with as few leaks as possible and ensuring the systems and processes for guarding the quality of the network are robust. One part of the network management system required to maintain high quality drinking water is ensuring the pipes are clean and sanitised prior to new connections being made into existing potable water networks. Another requirement is that sections of the network as they age, can become fouled with biofilm and deposits of minerals, clays and other inorganic particles that collect or scale over time. Regular flushing of water lines helps to remove these build ups but over time, even flushing alone cannot remove these contaminants.

Two key concepts important for a high standard of drinking water are pipeline cleaning and disinfecting processes. These concepts are similar but affect different attributes of safe, clean, quality drinking water. The first, pipeline cleaning, is the action of removing biofilm and other deposits that can contribute to poor water quality in terms of the physico-chemical aspects such as FAC (Free Available Chlorine), turbidity, colour and even taste. The second, pipeline disinfection, is the process to sanitise the pipeline to meet the biological standards such as E. Coli, HPC and TCC.

There are currently several techniques used for cleaning pipelines. Existing techniques typically require that the water in the line is flushed to waste. Existing techniques only clean the pipeline and require the addition of a disinfectant, at some point during the process to disinfect the pipeline to appropriate standards.

A commonly used disinfectant is chlorine. Chlorination involves filling the pipeline with a higher than usual level of FAC either as hypochlorite, chlorine dioxide or chloramine to over 5 mg/L. This is 10 - 20 times higher than the residual chlorine level that is used to maintain a typical disinfected pipeline that normally sits around 0.2 - 0.5 mg/L. This "super chlorinated" water is then held in the pipe for several hours, often up to 24 hours, sampled then held until the biological results are returned within 48 hours. The highly chlorinated water is then allowed to naturally decay to allowable drinking water guideline levels such as less than 5 mg/L FAC, or, alternatively, the water is flushed, via a chlorine destruction method using sodium thiosulphate for example, to waste. The water in the pipeline is flushed from the injection point to the outlet in batch sequence.

Microbial control, removal of biofilm and slime (the decaying remains of dead bacteria and other organic materials), microbial corrosion control and scale removal are significant maintenance issues for prolonging the production capacity and lifetime of potable water systems. Existing cleaning and disinfection techniques require large volumes of water to be flushed to waste during the process.

SUMMARY OF THE INVENTION

In an aspect, the invention provides a method for remediation of one or more water pipelines by circulating water through a water treatment plant, an ozone unit, the one or more pipelines to be remediated, and back to the water treatment plant, such that the one or more pipelines are cleaned and disinfected and water is regenerated and conserved.

In another aspect the invention provides a method for remediation of a water supply system comprising: isolating a portion of the water supply system to form a subnetwork containing water said subnetwork having at least one inlet and at least one outlet through which fluid flow into and out of the subnetwork is controllable; providing fluid communication from an outlet of the subnetwork to a mobile water treatment plant and a mobile ozone unit for generation of ozone dosing fluid wherein: an outlet of the water treatment plant is in fluid communication with at least one inlet of the ozone unit; an outlet of the ozone unit is in fluid communication with at least one inlet of the subnetwork; and, the water treatment plant provides substantially purified water to the ozone unit for generation of stabilised ozone dosing fluid; pumping ozone dosing fluid into subnetwork to remove deposits from and disinfect the inner surfaces of the subnetwork thereby forming a detritus water stream containing dissolved and undissolved solids; and flushing the detritus water from the system through an outlet of the subnetwork and passing the stream through the mobile water treatment plant to substantially remove the dissolved and undissolved solids such that water is regenerated and conserved.

Suitably, the water treatment plant provides purified and acidified water to the ozone unit. In some embodiments, the water treatment plant: filters, deionises and acidifies the detritus water stream.

In an embodiment, the subnetwork, mobile ozone unit and mobile water treatment plant form a recirculation loop. Suitably, the water in the loop is cycled through the loop until the ORP of the water stabilises.

In an embodiment, the ozone unit is in parallel with the subnetwork. Preferably, at least a portion of flow through the subnetwork is diverted into the ozone unit. In an embodiment the ozone unit is in series with the subnetwork.

The deposits may be organic or inorganic in composition. In some embodiments, the deposits are biological in origin.

In certain embodiments the water supply system comprises an existing pipeline. In some embodiments the water supply system comprises a recently commissioned system (new pipeline installation).

Suitably, the subnetwork is a subnetwork of a municipal water supply system. The subnetwork may be selected from a residential estate or an industrial estate.

Preferably, about 90% of the water is conserved.

Preferably, the target ORP at exit of the subnetwork is greater than 750mV for more than about 2 mins.

BRIEF DESCRIPTION OF THE DRAWINGS

The Detailed Description and Examples will make reference to a number of drawings as follows:

Figure 1 is a schematic representation of an embodiment of the present invention illustrating the mobile water treatment plant and ozone unit in a circuit with a water supply system subnetwork;

Figure 2 is a schematic representation of an embodiment of the present invention illustrating connection of the water treatment plant and ozone unit in a reticulated network environment for the purpose of disinfecting the whole circuit; and

Figure 3 is a schematic representation of an embodiment of the present invention illustrating connection of the water treatment plant and ozone trailer in a reticulated network environment for the purpose of disinfecting a subsection within that network.

DESCRIPTION OF THE EMBODIMENTS

As a preliminary matter, it will be readily understood by one having ordinary skill in the relevant art that the present disclosure has broad utility and application. The foregoing summary and following detailed description are merely exemplary in nature and are not intended to limit the described embodiments or the application and uses of the described embodiments. All of the exemplary implementations below are provided to enable persons skilled in the art to make or use the embodiments of the disclosure and are not intended to limit the scope of the disclosure. Furthermore, there is no intention to be bound by any expressed or implied theory presented in the preceding technical field, background, summary or the following detailed description. It is also to be understood that the specific systems and processes illustrated in the attached drawings, and described in the following specification, are simply exemplary embodiments of the inventive concept. Specific dimensions and other physical characteristics relating to the embodiments disclosed herein are therefore not to be considered as limiting unless the claims expressly state otherwise.

Any sequences(s) and/ or temporal order of steps of various processes or methods that are described herein are illustrative and not restrictive. Accordingly, it should be understood that although steps of various processes or methods may be shown and described as being in a sequence or temporal order, the steps of any such processes or methods are not limited to being carried out in any particular order or sequence, absent any indication otherwise. Indeed, the steps in such processes or methods generally may be carried out in various different sequences and orders while still falling within the scope of the present disclosure.

Additionally, it is important to note that each term used herein refers to that which an ordinary artisan would understand such term to mean based on the contextual use of such term herein. To the extent that the meaning of the term used herein - as understood by the ordinary artisan based on the contextual use of such term - differs in any way from any particular dictionary definition of such term, it is intended that the meaning of the term as understood by the ordinary artisan should prevail.

The present disclosure contains headers. It should be understood that these headers are used as references and are not to be construed as limiting upon the subject matter disclosed under the header.

Furthermore, it is important to note that as used herein "a" and "an" generally denote "at least one" but does not exclude a plurality unless the contextual use dictates otherwise. By way of example, "an element" means one element or more than one element.

When used herein to join a list of items, "or" denotes "at least one of the items", but does not exclude a plurality of items of the list. Finally, when used herein to join a list of items, "and" denotes "all of the items of the list".

As used herein, the term "about" means that the numerical value is approximate and small variations would not significantly affect the practice of the disclosed embodiments. When used to describe a value, the term "about" preferably means an amount within ±10% of that value.

As used herein, the term "biofilm" refers to the extracellular structures formed by microbial communities and includes related microbiota that grow attached on surfaces of, and live within or on, the biofilm.

The term "plurality" means "two or more", unless expressly specified otherwise. For example, "plurality" may simply refer to a multiplicity of microparticles (two or more) or an entire population of microparticles in a given composition or dosage form, e.g., for the purpose of calculating the size distribution of the microparticles.

As used herein the term "remediation" refers to the act of remedying or correcting something that has been corrupted or that is deficient.

As used herein the term "sanitise" and related terms such as "sanitising" and "sanitisation", refer to the reduction of pathogenic agents (such as bacteria) on the surfaces of something (an inanimate object). In a further related context, a "sanitiser" is an agent that reduces the number of bacterial contaminants to safe levels as judged by public health requirements. Sanitisation may be effected through means such as: chemical and physical agents, thermal treatment and irradiative processes.

In a similar sense, as used herein the term "disinfection" refers to the destruction of pathogenic microorganisms, or their toxins or vectors, by direct exposure to chemical or physical agents, and may be accomplished by other means such as thermal or irradiative processes. Disinfection does not typically involve sterilisation. That is, disinfection is less lethal than sterilization because it destroys most (but not all) recognized pathogenic microorganisms.

The term "disinfectant", is used to refer to agents (such as a chemical or physical agents) that destroys disease-causing pathogens or other harmful microorganisms but not necessarily all microbial forms (e.g., bacterial spores). The term disinfectant may be used to refer to chemical substances, such as ozone and ozone solutions, applied to inanimate objects.

Disinfection standards may be met by sanitisation processes through a rules-based approach for safe levels of bacteria/germs.

As used herein the term "potable" refers to water that is drinkable or safe to drink.

As used herein the term "reticulated", in relation to a water supply, refers to a piped water supply network.

As used herein the term "detritus" refers to waste or debris of any kind including, for example: gravel, sand, silt, or other material produced by erosion; and, organic matter produced by the decomposition of organisms.

As used herein the term "detritus water" refers to water containing dislodged or eroded mineral deposits and organic matter produced by the decomposition of organisms. The deposits may be scale and silt. The deposits may be biological in origin such as biofilm and/or associated biofilm degradation products.

As used herein the term "priming" refers to preparing something for use or action.

As used herein the term "standpipe" refers to a portable device used to draw water directly from a fire hydrant on watermains.

The invention provides an integrated water purification and recycling system. The invention provides a method for disinfecting and cleaning or both, a potable water pipeline by re-circulating the water through a mobile ozone generator (also referred to as an ozone trailer or ozone unit); a water supply system subnetwork such as the water pipeline to be disinfected or cleaned; a water treatment plant; and, back to the ozone generator unit in a re-circulation loop. Preferably the water treatment plant is a mobile water treatment plant (MWTP).

The water treatment plant includes a filtration system for removing the biofilm, silt and other solids removed from the inner surfaces of pipework. Suitably, the water treatment plant is comprised of media filters, for example: glass media filters, one or more pumps for subnetwork fluid re-circulation, and ion exchange resins. Suitably, the water treatment plant includes a filtration system for removing the biofilm, scale, silt and other solid deposits removed from the inner surfaces of pipework. Suitably, the filter is a back washable filter.

In some embodiments, the MWTP includes a facility to inject make-up water along with a booster pump to provide the flow rate and pressure for cleaning the subnetwork. Makeup water may be used for priming pumps, hoses and units such as the water treatment plant and ozone unit. Makeup water may be supplied from an external source such as a water tanker.

Suitably, the MWTP includes acidification and ion exchange means, such that water may be optionally passed through an ion-exchange process or acidified with the addition of, for example, a mineral acid. Preferably, the de-ionised, acidified water stabilises the aqueous ozone dosing fluid by removing ionic cationic contaminants such as metal ions and hydroxides that can degrade ozone.

Suitably, the method for re-circulating stabilised, ozonated water includes filling the MWTP with supply water from the makeup line. Suitably, the water treatment plant is primed with water from the subnetwork. Suitably, the water treatment plant is primed with makeup water from a water supply external to the subnetwork.

In some embodiments, a re-circulation loop may be formed using the reticulated pipe network itself. By the actuation of selected valves and other water lines, the water may be returned to the ozone generator with only a relatively short piece of lay-flat hose.

Suitably, once the lines, filters, pump and associated equipment are full and air has been removed, the ozone unit is started along with the circulation pump. Filtered, de ionised and/or acidified water may then be pumped to the ozone trailer that is located adjacent the subnetwork pipe to be cleaned, disinfected or both. Ozone is then injected and solubilised in the water and sent down through the subnetwork through an inlet in the target pipe. At an outlet of the subnetwork, the water is returned to the MWTP where the process continues until target ORP levels on exit of the pipe are achieved. Typically, inlet ORP levels are -900 - 1,OOOmV. The target ORP for effective disinfection is preferably greater than about 750mV on exit of the pipe for more than about 2 mins.

Potable Water System

The collection of pipes that convey drinking water is known as a potable water supply system but may be also be referred to variously as: a water supply system; a water network; drinking water supply system; or a public or municipal drinking water supply system or network. Water supply systems transmit or distribute potable water to, for example: homes, commercial establishments, industry, and agricultural (e.g. irrigation). Water systems may have a loop or branch network topology, or a combination of both.

Components of a water system includes pipes and valves that convey water and direct flow. A water system typically starts after a body of water is treated at a water treatment plant and ends at the point of discharge where the water is used or discharged to the environment. The term "subnetwork", or similarly a "subsystem", refers to a component part of the water system. Examples of subnetworks include: pipes such as water mains, submains, housing estates and industrial estates.

Suitably, remediation of a water system may be referred to as network cleaning or network disinfection.

Traditionally, water from an existing live main is first fed through the pipeline to be disinfected at a high flow rate to purge the pipes of dirt and other debris, with the outflow water containing detritus not conserved, but being run into, for example, a storm water system. Once the water runs clean the flow is stopped and disinfection of the pipeline is commenced.

Turbidity is the cloudiness or haziness of a fluid caused by large numbers of individual particles that are generally invisible to the naked eye. Drinking water utilities strive to achieve low levels of turbidity and the measurement of turbidity is a key test of water quality. The units of turbidity from a calibrated nephelometer are called Nephelometric Turbidity Units (NTU). Although national and regional guidelines may require turbidity to be less than 5 NTU (Australia) and even less than 4 NTU (Europe), turbidity levels in pipeline may be as high as 20 to 30 NTU up to 50 NTU or even greater. Water in municipal pipelines accumulates suspended solids over time due to a variety of factors including: line breaks, biofilm decay, sloughing of biofilm, water treatment plant filter breaks, pipe corrosion, clay and silt from source water too fine to be filtered or coagulated. Higher turbidity may result from, for example, an increase in colloidal organic and inorganic particles (e.g. sediment, clay or silt particles).

Ozone in solution is a reactive substance that may be quickly consumed by, for example, encountering a high organic (e.g. TOC) load. Feedwater to an ozone unit used to generate ozone disinfecting solutions may itself have unacceptably high NTU values. Network disinfection and cleaning typically requires long lengths of pipe to be remediated. If ozone in a disinfection solution is rapidly consumed, this limits the diameter and length of water pipes that can be cleaned and disinfected. Accordingly, it is preferable for the ozone disinfection solution circulated through a pipeline subnetwork to persist for longer to provide for greater ozone penetration throughout the network and to allow for cleaning and disinfection of greater length of pipeline within a network (e.g. on a lineal meter basis). Moreover, if the ozone persists for longer in solution (i.e. is not quickly consumed), then slower flow rates may be used, as well as pipes with larger diameters disinfected.

Advantageously, the integrated methods and systems disclosed herein conserve water through regeneration of the quality of water added to, or existing within the pipeline, thus allowing for recycling, whilst concomitantly improving the stability of the ozone dosing fluid generated in the ozone unit through use of feedwater to the ozone unit of low turbidity and low organic and ionic content. Preferably the water is regenerated to a potable standard.

Connection of the Subnetwork to External Processing Units

Referring to FIG. 1, in the embodiment illustrated, the target water supply pipeline 101 to be treated is isolated from the water supply system 100 by valves 102 and 103; the actuation of which closes off the portion of pipeline between valves 102 and 103 from the broader system 100. The subnetwork pipeline 101 to be remediated may form part of a public drinking water network for transmission and distribution of potable water. Pipeline 101 may form any of, for example: a main line, a sub-main line, a branch line or a sub-branch line. Fluid communication (including fluid removal and return) between pipeline portion 101 and processing units external to the pipeline may be achieved through establishing: (i) fluid connectivity, at an egress, such as outlet 105, which forms a T-junction on the pipeline and is terminated at gate valve 106; and (ii) fluid connectivity, at an ingress, such as inlet 104 which forms a T-junction on the pipeline and is terminated at gate valve 107. Inlets and outlets of the water supply system may be, for example, hydrants. The gate valves 106 and 107 may be coupled via attachment points 108 and 109 respectively, to fluid transfer lines, such as laydown pipes. Considering the outlet, pipe 110 attached at one end to gate valve 108 is attached 201 to an inlet 202 of the water treatment plant 200. The connection point 201 of the pipe 110 to the water treatment plant 200 may be considered a battery limit differentiating those unit operations which comprise part of the water treatment plant system and those objects external to the system. Accordingly, fluid connectivity between the pipeline 101 and the water treatment plant 200 (the various components of which are indicated within the hashed outline in the drawing), may be implemented by conduit 110 which is coupled 108 to gate valve 106 and attached 201 at junction 202 between pressure reducing valve 203 and ball valve 204. Opening of gate valve 106 and ball valve 204 provides a fluid flow pathway between the pipeline 101 and the water treatment plant 200.

To recapitulate, fluid communication, from pipeline 101 through outlet 105 and inlet 104, with the unit operations such as water treatment plant 200 and ozone plant 300, is achieved through actuation of gate valves 106 and 107 on pipeline 101. Continuing with the connection of the water treatment plant 200 to the pipeline, preferably, the water treatment plant 200 is a mobile water treatment plant that can be, for example, fitted onto a trailer such that it may be towed to a servicing location. Fluid conduit 110 may be any sort of suitable pipe, such as, for example, a 4" lay flat hose pipe. In some instances, and depending on the location of treatment plant 200 in relation to ozone unit 300, the length of the hose 110 required may be approximately commensurate with the length of the water pipeline 101 being remediated.

Makeup Water

Prior to commencing pipeline remediation, makeup water, such as from water supply line 111, may be used for priming pumps, hoses and units such as the water treatment plant 200 and ozone generation and dosing unit 300. The priming water removes air that may be contained in lines, pumps and other equipment. For example, the unit operations of the water treatment plant such as filtration units and ion exchange resins, may be charged with makeup water to remove air. Make-up water, such as a source of potable water, may be contained, for example, in a water tanker (not shown) connected to supply line 111. Depending on the location an availability, any suitable source of potable water may be used for make-up water. In the embodiment illustrated, the makeup water supply line 111 is gated by hand operated valve 112 which is coupled 113 to a conduit 114. The conduit 114 may be of variable length depending on the location of the water supply in relation to the water treatment plant 200. The conduit 114, which may be, for example, a hose pipe, is further coupled 115 to check valve 116, said valve which is followed by pressure reducing valve 203. The pressure reducing valve 203 is followed by a T-junction 202 whereat the conduit 110 is attached 201 ultimately providing fluid connectivity to pipeline 101 at this juncture.Optionally, makeup water may be drawn from the water supply system 100 from outside of the subnetwork pipeline 101.

Ozone Plant Outlet

Returning now to the connection between the inlet 104 of pipe 101 and the ozone generating unit 300, the outlet 117 of the ozone generating and dosing unit 300 is coupled 118 to a fluid conduit 119 which is ultimately attached 109, and in fluid communication with, pipeline access valve 107. Preferably, the ozone generation and dosing unit 300 is located as close as possible to the inlet standpipe 104 of the target pipeline 101 to be treated. This preferred proximity gives the higher concentration of ozone in the dosing fluid at the exit of the generator the optimum chance to disinfect pipe 101 before degradation of the ozone in solution commences reducing the efficacy of the dosing solution or fluid. Preferably the ozone generation and dosing unit 300 is a mobile unit. The ozone generation and dosing unit 300 is typically comprised of a water inlet 125 and attachment 126, and water outlet 117 and attachment 118 for respectively accepting pre-treated water and delivering treated (ozonated) water, an ozone injection system for dissolving ozone in the water (not shown), an ozone generator for supplying the ozone injection system (not shown), and a power generator for powering the various components of the plant (not shown). The plant is able to operate in a self-contained manner. An ORP meter is located at the outlet of the ozone unit to ensure the unit is operating properly.

Ozone Unit

As discussed, the systems and methods of the present invention include a portable ozone generation plant, sometimes referred to as an ozone trailer or an ozone unit 300. The plant is typically disposed on a tray and mounted on a vehicle, or the tray is, for example, formed as a trailer, for towing by a vehicle. The plant includes: a water inlet and water outlet for respectively accepting pre-treated water and delivering treated water; an ozone injection system for dissolving ozone in the water; an ozone generator for supplying the ozone injection system; and a power generator for powering the various components of the plant. The ozone generator is preferably a corona discharge ozone generator, which are manufactured using quartz tubes.

The water inlet contains the inlet connection, a check valve, a flowmeter and a pressure regulating valve, before the water flow bifurcates into two alternative streams, which may for the sake of convenience be termed a mainstream and a side-stream. A source of mains water or an alternative supply - pressurized or non-pressurized - is delivered to the water inlet, which is fed successively through a check valve, then a flowmeter, then a pressure regulating valve (PRV).

The mainstream passes to the ozone injection system, which is bypassed by the sidestream. The pressure regulating valve is used to regulate the pressure to the ozone injection system with minimal pressure loss. A water booster pump may be selectively used to increase the pressure to the ozone injector system, if the supply pressure is less than a preset amount.

Flowmeters are fitted to both the water inlet and sidestream of the plant to provide an indication of the volume of water flowing through the plant, and the proportion of that flow that is diverted via the sidestream. The sidestream also features a ball valve, and according to operation of the plant, receives none, some or all of the water flow through the plant. The ozone generator has its own oxygen regulator for accurate control of the oxygen supply. Power requirements of the ozone generator may be provided by an onboard diesel power generator. An ORP monitor/controller may be fitted in the outlet line of the ozone unit to show the effective oxidation level in the water. This provides a more useful measurement than dissolved ozone alone. The probe is installed in the outlet water flow after the merging of the sidestream water. Typically, the feed to the ozone generator is commercial grade oxygen. The oxygen flow may be varied depending on the requirements of the ozone generator.

The ozone injection system has the following components: a variable speed drive, a pump, an ozone injector, a mixer, a degasser, a degas relief valve, a water trap, an ozone destructor and interconnecting pipework, valves and unions. Water is supplied to the ozone injection module at a preset pressure determined by a pressure relief valve (PRV) in the water inlet. If the pressure falls below the preset pressure level, then the water booster pump automatically engages to boost the pressure to the target level, under the control of the variable speed drive and pressure transducer. The check valve prevents the output from the water booster pump from affecting the pressure to the sidestream, which continues around the trailer. In operation the flow of water to be treated is split between the injection system and the sidestream.

The suction of the gas inlet of the injector can be fine adjusted by the use of the injector bypass. The injector enables the ozone gas to be drawn in through the suction port and entrained into the water stream in a mix of very fine bubbles. The outlet from the injector is immediately fed to the mixer which further increases the mass transfer of the ozone gas into the water stream. From the mixer the flow is fed through a large radius bend into the degas/contact chamber. The function of the degas chamber is to provide further contact time under pressure to allow the maximum amount of ozone to dissolve and to separate any undissolved gas from the stream. Undissolved gas is separated in the vortex and collected in the chamber at the top of the degas chamber. Fully dissolved ozone flows to the bottom of the separator and is discharged.

The undissolved ozone off gas which collects at the top of the separator is released by the degas relief valve. The degas relief valve allows the undissolved ozone to escape by means of a float and lever but blocks the flow of almost all of the water. The escaping gas, with a small amount of water is first fed into a water trap and the gas only then enters the ozone destruct device. This device reconverts any ozone off gas, back into its initial state, that of oxygen. This converted oxygen is released to atmosphere. The pressure of the ozonated water flowing from the degas unit is controlled by a ball valve which is adjusted to produce a suitable amount of back pressure. The flow from the injection system is merged with the flow of the sidestream to provide a total flow to the water outlet.

Water Treatment Plant

Returning to the inlet of the water treatment plant 110, fluid communication between the pipeline 101 and the water treatment plant 110 is controlled by ball valve 204 and three way plug valve 127. Valve 204 may be actuated wide open and the back pressure controlled by valve 203. Plug valve 127 provides a means for draining the system of water at this location through drain pipe 128. Fluid traverses conduit 129 through inlets 130 and 131 into the parallel aligned filtration units 132 and 133. As required, and depending on the volume of water to be treated as well as the flow rate, several filtration units may be provided in parallel. One or more filters may be routed in or out of line depending on process demand. In some embodiments, filters may be aligned in a series configuration. For example, a sand filter may be arranged in series with a carbon filter. Furthermore, a filter bed may be layered with discrete layers of different filter materials, for example: gravel, sand, glass and carbon. Filters may work on the basis of, for example: mechanical filtration or absorption. Suitable mechanical filtration systems include, for example: cartridge sediment filters, media and multimedia filters, and precoat filters. Which filtration method is selected depends on the concentration and size of the suspended solids in the water and the rate at which water needs to be treated. Media filters such as sand filters have a relatively high contaminant removal capacity. Filters with fibre or ceramic filter material, can be made with a smaller and more uniform pore sizes and can be effective in removing small particles. Filter media may be of varying composition, for example: sand, glass, gravel, and charcoal, and pore sizes. Some filtration media, such as carbon filtration media, remove contaminants through adsorption. For example, organic compounds bond or stick to the surface of a carbon filter. Optionally, the water treatment plant may include disinfection methods such as: UV sanitization.

Adjacent to the inlets of filtration units 132 and 133 physicochemical process properties and conditions may be acquired, with sensors 134 and 135, including, for example: water quality data, pressure, temperature and flow rate. Water quality data may include, for example: conductivity, temperature, pH, turbidity, oxidation reduction potential (ORP) and ion selective electrodes (ISEs). Sensor 134 may be an ORP sensor logging and monitoring ORP values of the water returning from pipeline subsection 101. Although two sensors (134 and 135) are shown in Figure 1, different configurations of multiple sensors are contemplated. For example, pressure transducers may be employed to specifically and separately monitor the pressure of each filtration unit through logging of pressure differential across the filtration unit's inlet and outlets e.g. Fluid line pressure monitoring prior to the filtration units also allows for indirect monitoring of pipeline pressure so as to avoid over pressurization of the pipeline system which could lead to ruptures or other failures. Data acquired by probes 134 and 135 may be transmitted 136A, 136B to Remote Telemetry Unit (RTU) 137. Transmission from probes and sensors may be wireless or hardwired to the RTU 137. The Remote Telemetry Unit is used, for example, to control the system pressure, flow rates and to log acquired process data.

In the event of over pressurisation of the filter units 132 and 133, such as from blockages, filters 132 and 133 are fitted with pressure relief valves 138 and 139 respectively. The respective outlets 140 and 141 of filters 132 and 133 are recombined 142 prior to the fluid bypass circuit, which includes three-way valve 143. Sensors and or probes for data acquisition may be located at the outlets of the filtration devices. A preferred sensor 144 is a pressure sensor which similarly transmits 136C acquired data to the RTU 137. Valve 143 may be used to bypass pump 145. Suitably, pump 145 is a positive displacement pump such as a lobe pump. The pressure differential (146 and 147 measured across lobe pump 145) that controls pump speed and system pressure is monitored 148, said monitoring communicated to RTU 137. Valve 149 may be actuated to open line 136 to line 150 and in conjunction with valve 143 to isolate pump 145 from the system. Valve 143 may be actuated to open drain 151 or to provide fluid communication between conduits 142 and 150 via pump 145. When 150 is closed to 136 and open to pump 145 by operation of valve 149, and valve 143 opens conduit 142 to pump 145, then pump 145 in no longer bypassed and is in the fluid circuit.

Suitably, the method for re-circulating stabilised, ozonated water involves filling the water treatment plant 110 with supply water from the makeup line 111. Once the lines, filters, pump and associated equipment are full, and air has been removed, the ozone trailer 300 is started along with circulation pump (lobe pump) 145.

Fluid conduit 150 is connected to the inlet 152 of ion exchange column 153. Examples of ion exchange resins include Purolite anion and cation exchange resins such as PFA400 and C100 respectively. In some embodiments, the ion exchange column 153 is loaded with a cation exchange resin. In some embodiment, the ion exchange column 153 is loaded with an anion exchange resin. In some embodiments both cation and anion exchange columns are used in series.

After treatment of the water stream by passing through the ion exchange column, the water exits the column through outlet 154. The outlet 154 may be closed by actuation of ball valve 155. In the event of over-pressurisation, ion exchange column 153 is fitted with a pressure relief valve 156. In a similar manner to what was previously described in relation to sensors 134 and 135, properties such as pressure may be monitored at the column outlet with sensor 157, which is in communication 136E with the RTU 137.

The ion exchange column outlet is connected to ball valve 155 which, when in the closed position, isolates the water treatment plant from further downstream processes. Ball valve 155 is in turn coupled 158 to conduit 159 which provides fluid communication between the water treatment plant 110 and the ozone generation and dosing unit 300. The distal end, from the water treatment plant 110, of hose 159 is coupled 126 to the ozone unit 300 at inlet 125.

The removal of particulate matter and ions from the fluid stream prior to the fluid entering the ozone generation unit provides a feed water for the unit that promotes stabilisation of the ozone dosing fluid generated in the ozone unit.

Addition of Mineral Acid

Suitably, the water treatment plant includes both acidification and ion exchange means, such that water may be optionally passed through, for example: an ion-exchange column, or optionally receive the metered addition of an acid such as a mineral acid. Suitably, de-ionised, acidified water is a preferred precursor for the generation of aqueous ozone in the ozone generation unit. It has been found that the removal of metal contaminants through ion exchange, and the neutralization of hydroxides leads to a reduction of degradation of ozone and therefore a stabilized aqueous ozone solution.

Recirculation Loop

There are several ways that the re-circulation loop including the MWTP may be closed or completed. Referring to FIG. 2, the arrangement of pipes 401, 402, 403 and 404, is a subsystem 400 of a water supply to be treated. The subsystem 400 is isolated from broader system 100 and the MWTP 200 and ozone unit 300 are introduced inline into the subsystem. The symbols indicated by: 100A, 401A, 402A, 402B, 403A, 403B, 404A, and 404B are representative of access points to pipelines, such as hydrants which, may be connected to, for example, stand pipes, allowing access into and out of the water pipeline network. In order to isolate the subnetwork from the broader water supply system, valves 405, 406, 407 and 408 are actuated to the closed position. Valves 409, 410 and 411 are maintained in an open position to allow water to flow around a circuit in the subsystem. Access point 401A is attached to a conduit 412 to provide fluid communication between the MWTP 200 and the circuit. Valve 413 is closed to bring the MWTP 200 inline with the subnetwork as all subnetwork flow is diverted through conduit 412 with the closure of valve 413. Depending, for example, on the flow rate through the subsystem, valve 414 may be actuated into either a close or open position. For example, if the flow rate is high treated fluid outputted from the MWTP 200 may be bifurcated into flows 415A and 415B. In this case, valve 414 may be actuated in the open position and flow 415B enters the subnetwork through access point 1OOA. If the flow rate is lower, then all of the output from the MWTP 200 may be output through conduit 415B to the ozone unit 300. In this case, access point 100A may be actuated to the closed position. The output flow 416 from the ozone unit 300 is connected to the subnetwork at 402A closing the recirculation loop. Preferably, the ozone trailer 300 should be as close to the inlet standpipe of the target pipeline to be treated as possible. This gives the higher concentration of ozone on exit of the generator the optimum chance to rapidly disinfect the pipe.

Considering now FIG. 3, an alternative embodiment of the present invention is schematically represented. In the embodiment of FIG. 3, the subnetwork 400 comprising pipes 401, 402, 403 and 404 is at least partially isolated from the broader water supply system by closing valves 405, 406, 407 and 408. Valves 409 and 411 within the subcircuit are maintained in the open position to allow fluid to circulate. The fluid in the circuit is diverted to the MWTP 200 by closing valve 413. Fluid is then diverted through the outlet 401A into hosepipe 412 where the fluid is treated in the MWTP 200. The output of the MWTP 200 is then returned to the pipeline via conduit 417 which is attached to the pipeline at inlet 402A. Fluid communication between the MWTP 200 and the ozone unit 300 is achieved via pipes 402 and 403 which comprise part of the subnetwork. At least part of the flow of water, previously treated in the MWTP 200, is the diverted 419 to the ozone unit 300 through outlet 403B. Depending on the flow rate within the subnetwork, valve 410 may be completely closed so that all fluid in the circuit is diverted through ozone unit 300. Alternatively, only a portion of the flow may be diverted and valve 410 may be kept at least partially open. After addition of ozone to fluid in the ozone unit 300 the ozonated fluid is returned 418 to the circuit 400 via an inlet 404B.

EXAMPLES

Trial 1

The aim of trial 1 was to develop a method for validating the functional performance of the equipment and prove that the recyclability concept could deliver an effective cleaning and disinfection program for a single pipe length whilst saving > 90% of the water required in the process.

Method

The following network pipe section was chosen:

• Pipe diameter: 250mm * Pipe length: 250m * Pipe Material: Polyethylene * Flow rate: 30L/s

The configuration of unit operations for the trial was substantially as described in Figure 1. The connecting length of lay-flat hose that returned the water after filtration to the ozone trailer was -250m. During this trial, there was no capability to use other network pipes for the recycling capability.

The MWTP was filled with water from the make-up line and air expelled until a constant water stream came through the ion exchange resin. This small amount of water was discharged to storm water at pH 6.

Once the air had been removed from the MWTP, all hoses were connected, the ozone trailer started and ozonated water opened to the pipeline being treated. The MWTP pump was then switched on to allow for recirculation of the water to commence. ORP and turbidity values were recorded over time.

Results

The MWTP operated exactly according to the project plan with pressures maintained between the target set points (200 - 600kPa). The MWTP pump flow and pressure is regulated by a hydraulic flow control valve evaluating the discharge pressure from the pressure sensor on exit of the cationic exchange resin (600kPa). The inlet pressure is maintained by a pre-set pressure reducing valve on the filter inlet on the make-up water line (200kPa). If the pressure dropped below this level, make-up water was added automatically.

The ORP values on the discharge of the pipeline were recorded and are provided below in Table 1. The target parameters for successful disinfection are:

• ORP > 750mV for > 2 mins • Turbidity < 5NTU

Table 1: ORP vs Time for the recirculation trial.

Time ORP (mV) Turbidity (NTU) 0 390 11 15 450 5 30 440 3 45 460 2 60 520 2 75 550 1 90 620 1

105 680 0.4 120 730 0.4 135 760 0.4

Results from the final sample taken after 145 mins passed all ADWG parameters, especially including the biological tests for E.Coli, HPC, turbidity and colour apparent. The following calculation describes the water saving realised compared to not recycling water.

At a flow rate of 30L/s and the trial conducted over 135 mins, the typical consumption of potable water that a standard ozonation process would have used for this section of pipe would have been 243KL water.

The water used for this example of re-circulating aqueous ozone includes:

250m of 100mm Lay-flat volume = 3.14 x 0.100m 2 x 250m / 4

= 7.85KL

Rest volume of water in the MWTP including associated connecting pipes is - 4KL. Only the water required to fill the MWTP, pipes and the lay flat hose with an insignificant amount of makeup water was effectively consumed. The total of water consumed in this example was -12KL which represents a -95% saving on water consumption to achieve the same level of disinfection and pipe cleaning success.

Noted that backwashing water to clean the filter along with exchange resin re-charge flushing also contribute to additional water usage but this only represents <1% of additional water per treatment since the MWTP can hold up to 280 kg of removed solids from potable water pipelines. The MWTP is only backwashed once the inlet pressure differential to the discharge pressure is reduced to < 1OOkPa. After 21 trials and more than 17 km of treated pipework, the MWTP had yet to be backwashed while maintaining outstanding turbidity, colour and biological control. Overall, trial results indicate that:

• Significant gains of 95% water savings were achieved. • Process control including managing the pressure in the network was maintained effectively and avoided risk to network infrastructure through over pressurising the treated pipe. • Disinfection capability maintained.

* Water quality control within ADWG achieved.

CITATION LIST

Jerry A. Nathanson, Professor of Engineering, Union County College, Cranford, New Jersey. Author of Basic Environmental Technology: Water Supply, Waste Disposal, and Pollution Control.)

Claims

THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS:

1. A method for remediation of one or more water pipelines by circulating water through: a water treatment plant, an ozone unit, the one or more pipelines to be remediated, and back to water treatment plant, such that the one or more pipelines are cleaned and disinfected and water is regenerated and conserved.

2. A method for remediation of a water supply system comprising: (a) isolating a portion of the water supply system to form a subnetwork containing water said subnetwork having at least one inlet and at least one outlet through which fluid flow into and out of the subnetwork is controllable; (b) providing fluid communication from an outlet of the subnetwork to a mobile water treatment plant and a mobile ozone unit for generation of ozone dosing fluid wherein: (i) an outlet of the water treatment plant is in fluid communication with at least one inlet of the ozone unit; (ii) an outlet of the ozone unit is in fluid communication with at least one inlet of the subnetwork; and, (iii) the water treatment plant provides substantially purified water to the ozone unit for generation of stabilised ozone dosing fluid; (c) pumping stabilised ozone dosing fluid into subnetwork to remove deposits from and disinfect the inner surfaces of the subnetwork thereby forming a detritus water stream containing dissolved and undissolved solids; and (d) flushing the detritus water from the system through an outlet of the subnetwork and passing the stream through the mobile water treatment plant to substantially remove the dissolved and undissolved solids; such that water is regenerated and conserved.