WASTEWATER TREATMENT SYSTEM

FIELD OF THE INVENTION

The present invention relates to systems, apparatus and methods for treatment of water and wastewater systems. In particular, the present invention relates to systems, apparatus and methods for odor control and/or cleaning of components which collect and transport water or waste material, such as wet wells, tanks, pumping stations, drains, and pipes.

BACKGROUND TO THE INVENTION

The effective treatment of wastewater is a basic necessity in any community. Wastewater and water systems all require some form of treatment to clean, disinfect, deodorise, reduce the concentration of poisonous gases and control the buildup of biofilm and other corrosive substances on the equipment used to collect and transport water or waste material through these systems.

Poisonous gases, such as hydrogen sulfide (H ₂ S), ammonia, hydrogen and/or methane accumulate in sewage systems due to the decomposition of organic wastes by

bacteria. H ₂ S, in particular contributes to the bad odor of wastewater and sewage systems. The gas has a characteristic foul odor of rotten eggs, is very poisonous even at low concentrations, corrosive, flammable, and potentially explosive. The presence of H ₂ S and other odor-causing compounds in waste materials is a major concern for waste handling systems, and generally regarded as a public nuisance and a health hazard to locals residing around such treatment plants.

In addition to the odor issue, the accumulation of toxic gases such as H ₂ S and methane in confined spaces such as tanks and wet wells pose a hazard to maintenance staff, and impede thorough cleaning of such facilities. Entry may be restricted according to strict criteria e.g., suitable breathing apparatus and safety equipment.

Odor problems are commonly treated using chemicals. Chlorine compounds such as bleach and calcium hypochlorite are common examples of chemicals for controlling H ₂ S in wastewater collection systems. The environmental impact and toxicity of these chemicals are obvious disadvantages.

Biofilm comprises a group of microorganisms held together and protected by a matrix of secreted polymeric compounds, called the extracellular matrix. Biofilms grow on the solid supports in sewage treatment plants, where they may play a beneficial role in processing of sewage for example by removing organic matter. However, biofilms are also found on the surfaces of water tanks, pipes, food-processing vessels, drains, etc., where the bacteria adhere tenaciously, protected by the dense extracellular matrix. The extracellular matrix resists removal by washing and protects the bacteria from common disinfectants and some antibiotics which cannot easily penetrate the matrix. Uncontrolled build-up of biofilm poses numerous issues including corrosion, clogging, loss of process efficiency such as heat transfer, and public health issues such as Legionella infection.

Chemical products are commonly used for cleaning and control of biofilms. Common chemicals include surfactants, which suspend and dissolve surface residues by decreasing surface tension, emulsifying fats, and denaturing proteins. An effective cleaning procedure must break up or dissolve the extracellular matrix so that disinfectants can gain access to the viable cells.

The use of "green" detergents comprising and/or blended with specific enzymes, bacteria or bacteriophage, can serve as a viable option to control biofilm and poisonous gas buildup. The enzymes, and bacteria-produced enzymes in these detergents help to break down fats, proteins and starches. Additionally, certain species of bacteria interfere with the biofilm production by competing with existing biofilm colonies.

In this specification where reference has been made to patent specifications, other external documents, or other sources of information, this is generally for the purpose of providing a context for discussing the features of the invention. Unless specifically stated otherwise, reference to such external documents is not to be construed as an admission that such documents, or such sources of information, in any jurisdiction, are prior art, or form part of the common general knowledge in the art.

It is an object of the present invention to provide improved systems, apparatus and methods for treating components associated with water systems and wastewater systems.

It is an additional or alternative object of the present invention to provide improved systems, apparatus and methods for continuous and/or remote monitoring and maintenance of such components, or to at least provide the public with a useful choice.

SUMMARY OF THE INVENTION

In one aspect, the present invention broadly consists in a system for treating a component of a wastewater system, comprising : a foam dispenser unit,

a control system for controlling operation of the foam dispenser unit according to one or more parameter thresholds,

wherein the foam dispenser unit dispenses a foaming treatment composition comprising a foaming agent and at least one biological agent onto surfaces of said component of the wastewater system.

According to another aspect, the foam dispenser unit comprises at least one nozzle.

According to another aspect,the foam dispenser unit dispenses the foaming composition onto internal surfaces of said component of the wastewater system via a fixed nozzle or nozzles.

According to another aspect,the foam dispenser unit dispenses the foaming composition onto internal surfaces of said component of the wastewater system via a rotating spray head.

According to another aspect, the foam dispenser unit dispenses the foaming composition onto internal surfaces of said component of the wastewater system via a rotating spray head.

According to another aspect, the system further comprises a foam generator unit upstream of the foam dispenser unit for generating the foaming treatment composition, wherein the foam generator unit is in fluid connection with the foam dispenser unit.

According to another aspect, the biological agent comprises one or more of:

a. enzymes,

b. bacteria,

c. bacteriophage,

d. fungi,

e. spores,

f. endospores.

According to another aspect, the foaming agent comprises a surfactant. According to another aspect, the surfactant is a bio-surfactant.

According to another aspect, the foaming of the treatment composition is assisted by compressed gas. According to another aspect, the control system controls operation of the foam generator unit and/or foam dispenser unit according to one or more of:

a. concentration of a gas in said component of the wastewater system, b. concentration of a liquid in the wastewater within said component, c. level of wastewater within said component,

d. time elapsed since previous treatment cycle

e. time according to a predetermined schedule,

f. visual observation of said component of the wastewater system, g. a manual override.

According to another aspect, the gas is hydrogen sulfide.

According to another aspect, the system further comprises a camera configured to transmit images of said component of the wastewater system to a remote monitoring device for visually observing said component.

According to another aspect, the system further comprises a light source positioned within said component of the wastewater system.

According to another aspect, the control system controls the duration of operation of the foam dispenser unit.

According to another aspect, the control system controls the thickness of the foaming treatment composition generated by the foam generator unit.

According to another aspect, the control system outputs data remotely to a user, to enable remote monitoring and control of the treatment system.

According to another aspect, manual override is performed remotely from said component of the wastewater system.

According to another aspect, the foaming treatment is supplied to the foam dispenser unit from a storage container.

According to another aspect, supply of the foaming agent and the biological agent to the foam dispenser unit is controlled by the control system. According to another aspect, the foaming agent and the biological agent are supplied to the foam generator unit from separate storage containers.

According to another aspect, the volume of each of the foaming agent and biological agent supplied to the foam generator unit is controlled according to one or more parameter thresholds.

In another aspect, the present invention broadly consists in a system for treating a component of a wastewater system, comprising :

a treatment dispenser unit comprising at least one spray nozzle,

wherein the treatment dispenser unit dispenses a treatment comprising at least one biological agent in a thixotropic composition onto surfaces of said component of the wastewater system.

According to another aspect, the thixotropic composition is shear thinned prior to dispensing onto surfaces of said component of the wastewater system.

According to another aspect, the system further comprises a pump for shear thinning the thixotropic treatment prior to dispensing.

According to another aspect, the pump is a double diaphragm pump.

According to another aspect, the treatment dispenser unit dispenses the thixotropic composition onto internal surfaces of said component of the wastewater system via one or more moving nozzles.

According to another aspect, the treatment dispenser unit dispenses the thixotropic composition onto internal surfaces of said component of the wastewater system via a fixed nozzle or nozzles.

According to another aspect, the treatment dispenser unit dispenses the treatment onto internal surfaces of said component of the wastewater system via a rotating spray head.

According to another aspect, the biological agent comprises one or more of:

a. enzymes,

b. bacteria,

c. bacteriophage,

d. fungi,

e. spores, f. endospores.

According to another aspect, the treatment composition comprises a thixotropic carrier.

According to another aspect, the thixotropic carrier comprises one or more of:

a. Natural gum,

b. Synthetic gum,

c. Rheology modifier.

According to another aspect, the system further comprises a control system for controlling operation of the treatment dispenser unit according to one or more parameter thresholds.

According to another aspect, the control system controls operation of the treatment dispenser unit according to one or more of:

a. concentration of a gas in said component of the wastewater system, b. concentration of a liquid in the wastewater within said component, c. level of wastewater within said component,

d. time elapsed since previous treatment cycle

e. time according to a predetermined schedule,

f. visual observation of said component of the wastewater system, g. a manual override.

According to another aspect, the gas is hydrogen sulfide.

According to another aspect, the system further comprises a camera configured to transmit images of said component of the wastewater system to a remote monitoring device for visually observing said component.

According to another aspect, the system further comprises a light source positioned within said component of the wastewater system.

According to another aspect, the control system controls the duration of operation of the treatment dispenser unit.

According to another aspect, the control system controls the viscosity of the dispensed treatment composition by controlling one or more of:

a. the duration of shear thinning of the composition,

b. the amount of shear force applied to the composition. According to another aspect, the control system outputs data remotely to a user, to enable remote monitoring and control of the treatment system.

According to another aspect, manual override is performed remotely from said

component of the wastewater system.

According to another aspect, the treatment composition is supplied to the treatment dispenser unit from a storage container.

According to another aspect, the thixotropic carrier comprises a plurality of components, wherein each component is supplied to the treatment dispenser unit from a separate storage container.

According to another aspect, the biological agent is added to the thixotropic carrier prior to dispensing the treatment onto surfaces of said component of the wastewater system.

According to another aspect, the biological agent is supplied to the treatment dispenser unit from one or more of said separate storage containers.

According to another aspect, the components are mixed in a mixing tank prior to input into the treatment dispenser unit.

According to another aspect, the components are mixed in-line prior to input into the treatment dispenser unit.

According to another aspect, supply of each component to the treatment dispenser unit is controlled by the control system.

According to another aspect, the volume of each of the components supplied to the treatment dispenser unit is controlled according to one or more parameter thresholds.

According to another aspect, said storage container(s) is/are refillable remotely from said component of the wastewater system.

According to another aspect, the storage container(s) is/are located within said component of the wastewater system. According to another aspect, said storage container(s) is/are located within an enclosure, and wherein said storage container(s) is/are refillable through one or more fill port(s) in a wall of the enclosure.

According to another aspect, the level of content in the storage container(s) is monitored via a level sensor.

According to another aspect, the level sensor is an ultrasonic sensor.

According to another aspect, the level sensor data is transmitted remotely to a user, to enable remote monitoring of the storage container(s).

In another aspect, the present invention broadly consists in a system for treating a component of a wastewater system, comprising :

a treatment dispenser unit,

one or more storage container(s) supplying treatment to the dispenser unit, wherein the storage container(s) is/are refillable remotely from said component of the wastewater system.

According to another aspect, the storage container(s) is/are located within said component of the wastewater system.

According to another aspect, said storage container(s) is/are located within an enclosure, and wherein said storage container(s) is/are refillable through one or more fill port(s) in a wall of the enclosure.

According to another aspect, the level of content in the storage container(s) is monitored via a level sensor.

According to another aspect, the level sensor is an ultrasonic sensor.

According to another aspect, the level sensor data is transmitted remotely to a user, to enable remote monitoring of the storage container(s).

In another aspect, the present invention broadly consists in a method of treating a component of a wastewater system, comprising steps of:

a. generating a foaming treatment composition comprising at least one biological agent, b. dispensing the foaming composition onto said component of the

wastewater system,

wherein one or both of said steps is/are controlled via a control system according to one or more parameter thresholds.

According to another aspect, the treatment composition comprises one or more of:

a. enzymes,

b. bacteria,

c. bacteriophage,

d. fungi,

e. spores,

f. endospores.

According to another aspect, the control system controls one or both of the steps of generating the foaming composition and dispensing the foaming composition according to one or more of:

a. concentration of a gas in said component of the wastewater system, b. concentration of a liquid in the wastewater within said component, c. level of wastewater within said component,

d. time elapsed since previous treatment cycle

e. time according to a predetermined schedule,

f. visual observation of said component of the wastewater system, g. a manual override.

According to another aspect, the gas is hydrogen sulfide.

According to another aspect, the method further comprises a step of visually observing said component of the wastewater system via a camera configured to transmit images of said component to a remote monitoring device.

According to another aspect, the control system controls the duration of dispensing of the foaming composition.

According to another aspect, the control system controls the thickness of the foaming treatment composition generated.

According to another aspect, the control system outputs data remotely to a user, to enable remote monitoring and control of the treatment method. According to another aspect, manual override is performed remotely from said

component of the wastewater system.

In another aspect, the present invention broadly consists in a method of treating a component of a wastewater system, comprising a step of:

applying a thixotropic treatment composition to said component of the

wastewater system,

wherein the treatment composition comprises one or more of:

a. enzymes,

b. bacteria,

c. bacteriophage,

d. fungi,

e. spores,

f. endospores.

According to another aspect, the treatment composition comprises a thixotropic carrier comprising one or more of:

a. a natural gum,

b. a synthetic gum,

c. a rheology modifier.

According to another aspect, the method further comprises a step of shear thinning the thixotropic treatment composition prior to applying the treatment to said component of the wastewater system.

According to another aspect, the treatment composition is applied to said component of the wastewater system via at least one spray nozzle.

According to another aspect, the treatment composition is supplied to the spray nozzle from a storage container.

According to another aspect, the thixotropic carrier comprises a plurality of components, wherein each component is supplied to the spray nozzle from a separate storage container.

According to another aspect, the method further comprises a step of adding the biological agent to the thixotropic carrier prior to dispensing. According to another aspect, the biological agent is supplied to the spray nozzle from one or more of said separate storage containers.

According to another aspect, the step of applying the thixotropic treatment composition is controlled by a control system according to one or more parameter thresholds.

According to another aspect, the volume of each of the components supplied to the spray nozzle is controlled by a control system according to one or more parameter thresholds.

According to another aspect, the one or more parameter threshold(s) is/are:

a. concentration of a gas in said component of the wastewater system, b. concentration of a liquid in the wastewater within said component, c. level of wastewater within said component,

d. time elapsed since previous treatment cycle

e. time according to a predetermined schedule,

f. visual observation of said component of the wastewater system, g. a manual override.

According to another aspect, said component of the wastewater system is a wet well.

For brevity, the following description will refer to "wastewater" systems, although the treatment system of the present invention may be applied to sewage, waste or water systems.

The term "comprising" as used in this specification and claims means "consisting at least in part of". When interpreting each statement in this specification and claims that includes the term "comprising", features other than that or those prefaced by the term may also be present. Related terms such as "comprise" and "comprises" are to be interpreted in the same manner.

This invention may also be said broadly to consist in the parts, elements and features referred to or indicated in the specification of the application, individually or collectively, and any or all combinations of any two or more said parts, elements or features, and where specific integers are mentioned herein which have known equivalents in the art to which this invention relates, such known equivalents are deemed to be incorporated herein as if individually set forth.

The invention consists in the foregoing and also envisages constructions of which the following gives examples only. BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the invention will be described by way of example only and with reference to the drawings, in which :

Figure 1 is a schematic drawing showing the basic components of the treatment system according to one embodiment.

Figure 2 is a detailed cross-sectional view of the foam dispenser unit of Figure 1.

Figure 3 is a schematic drawing showing the basic components of the treatment system according to another embodiment.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The present invention envisages improved treatment of components of wastewater systems through the use of treatment compositions with specific properties. In particular, the treatment composition is specifically chosen to increase the coverage and/or persistence of the treatment on exposed surfaces of the wet well or other component of the water or wastewater system.

Additionally, the confined and hazardous natures of these wastewater components impede effective and cost-efficient treatment of these components. In particular, the present invention addresses difficulties in monitoring such systems, and in customising the treatment regime on demand.

For brevity, the following description will refer mainly to wet wells although it should be understood that the treatment system and methods of the present invention may be applied to various other components of water system or wastewater treatment system, such as tanks, pumping stations, drains, and pipes.

In one preferred embodiment shown in Figure 1, the treatment system involves the use of a foaming or foamable composition that is applied to the interior surfaces of the wet well.

The foam coats and clings to exposed areas of the wet well, so that cleaning agents in the foam can remove and dissolve dirt and organic matter such as fats, proteins and starches (Fats, Oils and Grease "FOG"). Further, the layer of foam can have the additional benefit of capping the area to prevent odour escaping. Some amount of foam coating may persist even when the wet well is subsequently refilled, thus prolonging the treatment. The foam that fails to adhere to the sides of the well will remain mixed with or floating on top of the contents of the well when it is subsequently refilled and emptied, so that the foaming treatment can carry out its purpose further down the system. It has been found that the system can provide downstream benefits as far as 2 km, from the primary treatment site.

Additionally, as will be described in further detail below, the treatment preferably introduces specific strains of bacteria and/or enzymes that will help to hydrolyse the organic material and control the proliferation of the biofilm (FOG) on such surfaces. The persistence of the foam composition promotes the proliferation of the beneficial bacteria.

The treatment method preferably additionally leaves a layer of foam that will float at the top of the contents of the wet well when it is refilled. The floating cover may reduce the build-up of toxic gases and output of foul odors from the wet well. Atomisation of bacteria and/or enzymes is not desirable as this may cause it to drift and potentially be breathed in by humans are animals. The foamed treatment limits atomisation of bacteria and/or enzymes.

Additionally, the treatment foam is preferably sufficiently stable to produce a flow-on effect in downstream components of the wastewater system. It has been found that the foam treatment removes fat build-up and reduces H ₂ S levels in the downstream wet well, as well as the piping system that connects the wet wells.

In the preferred embodiment, the foaming or foamable treatment comprises a foaming agent and a biological agent. The foaming agent is preferably a surfactant, although sufficiently stable foams may also be generated using other foaming additives (e.g., polymers, fatty acids), and/or be assisted by compressed gas. The surfactant may be any type of anionic, cationic, non-ionic or zwitterionic surfactant as known in the art.

Alternatively, the surfactant may be a bio-based surfactant or bio-surfactant produced by a biosurfactant-producing microbe. An example is surfactin, which is produced by the bacteria Bacillus subtilis. The surfactant component in the foaming or foamable treatment may comprise any one or a combination of more than one of these

surfactants.

The biological agent of the treatment composition comprises any one or a combination of enzymes, bacteria, bacteriophage and fungi found to be effective in controlling the formation and development of biofilms. The biological agent may additionally or alternatively be suitable components of the relevant microorganism, such as the endospores of bacteria, spores of fungi, etc. The biological agent may additionally help to hydrolyse and remove organic material from the treatment surfaces.

The treatment composition may also include further cleaning additives such as biocides, chelating agents and bleach and other additives such as preservatives, stabilisers, fragrances, etc.

The formulation of treatment products containing enzymes, bacteria, bacteriophage, fungi, spores, and/ or endospores is known. Further, methods of stabilising these active ingredients are also known. Preferably the microorganism is in a vegetative state or dormant state, for example, an endospore. In yet other embodiments, the

microorganism is present in a mixture of dormant and vegetative states. This can be achieved in many ways by the use of over salting, addition of MPG, binding or drying or lowering the pH and then preserving with a food grade preservative (Sodium Benzoate) for example. It is common to also add certain ingredients for chelating such as EDTA, GDTA and the like.

In order to enhance stability, it is preferred to supply the foaming agents and any of the following, enzymes, bacteria, bacteriophage, fungi, spores, endospores in separate solutions for long term stability and cost reduction. Alternatively, two or more

components can be blended together and stabilised as necessary.

The blending of surfactants depends on the application and requirements, however a person skilled in the art is able to achieve this easily. An appropriate surfactant can come from any family of surfactants and can be blended to achieve the best outcome for the specific environment and requirements. For example McCutcheon's Emulsifiers &

Detergents, International Edition, 1998 lists a number of suitable examples at pages 223 to 231 of the HLB index.

The foaming treatment preferably clings onto both vertical and horizontal surfaces.

Additionally, upon dispensing from a spray head (described in more detail below), the voluminous foam can cover a larger surface area of the wet well.

A foamed treatment is used for one or more of three primary reasons, being :

1. for the foam to hold the bacteria/enzymes in solution, to give long contact times to allow the enzymes to work,

2. a blend of different HLB's allows the interaction between FOG and water which, without help would not happen easily, this also allows emulsification of the FOG which makes the FOG easier for the enzymes to use, basically allowing a greater surface area for the enzymes to work on.

3. The use of surfactants to make foam allows treating of only the areas where FOG builds up, in the tidal zone, this allows for a stronger application rate but still using less volume of Bacteria/ enzymes (instead of treating the whole volume of water).

During treatment, the FOG's are a food source for the bacteria and/or enzymes. FOG's are basically triglycerides, and by using Bacteria that produces Lipase Enzymes (fat eating) or using a Lipase enzyme directly, the enzymes remove one of the legs off the Triglycerides and frees the carbon in the FOG for reproduction of the bacteria. Once the enzymes have finished with the FOG, it is no longer a Triglyceride so therefore cannot reform as a solid fat.

Triglycerides are changed into Diglycrides and free fatty acids (see diagram below, PL2, TL or PL1 is the enzyme in this case a Phospholipid Triglyceride Lipase enzyme).

Diglyceride or Free fatty

lysophospholipid acid (FFA)

Triglyceride or „ .

phospholipid (depending on R ₃ >

Figure 1 shows the basic components of the treatment system according to the first embodiment. The system comprises a foam generator unit 1 upstream of, and in fluid connection with, foam dispenser unit 2. Alternatively, the system could comprise a single unit which generates and dispenses the foam.

The foam generator unit 1 receives the components of the foamable treatment composition separately from bulk storage tanks, designated 3 and 4 in figure 1. While two tanks are shown schematically, it should be understood that the foamable composition may comprise any suitable number of separately stored components (including a single component, comprising the biological agent), so that the treatment may be mixed and/or foamed on demand.

The boxes in dotted lines in Figures 1 and 3 schematically highlight several components that are optional in that they may or may not be present in each of the preferred embodiments. It will become clearer in the following description what alternative elements or combinations may be present. Preferably, foam generator unit 1 receives compressed air and water from air compressor 5 and water supply line 6 respectively. The water supply may be pressurised if required. The thickness of the foaming composition may be varied according to the pressure of the gas and/or the water supply. Preferably, these pressures are controlled by the control system described below.

Additionally or alternatively, the foam generator unit may receive other types of compressed gas if required for foaming the treatment composition. For example, carbon dioxide may be supplied from cylinders (not shown) or produced on-site e.g., by combining hydrochloric acid and calcium carbonate. In another example, ozone may be used, which additionally functions as a disinfectant and deodorant.

Controller 9 may comprise a programmable logic controller (PLC) or other control system for automating the operation of the foam generator unit 2, the foam dispenser unit 3, and/or the refilling of the bulk storage tanks 4, 5, etc. The controller 9 receives input, preferably in real time, from the various sensors, meters, camera, and other monitoring devices as described in more detail below.

The controller 9 may also comprise a human-machine interface, graphical interface, manual override controls, safety switches, etc., for displaying data to and/or receiving input from the maintenance operator. In such cases, the controller is preferably located away from the wet well or other potentially hazardous sites to allow for safe control and monitoring of the treatment system.

The controller 9 may be connected, via any suitable wired or wireless connection, to other devices, for example, personal devices such as cellphones, desktops and laptops. Suitable means of data transfer may be via, for example, Ethernet, cellular data networks, Wi-Fi, or mobile satellite networks. Preferably, the controller 9 is also able to receive instructions from these devices. This allows for remote control and monitoring, preferably continuously and in real time, of the wet well by maintenance personnel.

In addition to controlling normal operation of the system, the controller 9 is preferably also configured to transmit alarms to the operator, in the event of a problem such as flooding of the wet well, equipment malfunction, unusually high levels of toxic gas, etc. these alarms and/or logs are preferably accessible via the Internet and/or a hardwired system. Foam dispenser unit 2, shown in more detail in Figure 2, is positioned in the wet well 10 or other component of the wastewater system to be treated. In the case of a wet well, the foam dispenser unit 2 is preferable positioned at or adjacent the top and middle of the well, so that the foam may be sprayed onto the upper section of each wall, and drip under gravity to coat all internal surfaces of the wet well. Most preferably, the foam dispenser unit is mounted on a ceiling or cover of the wet well.

Preferably, foam dispenser 2 comprises a rotary spray head 7 having at least one spray nozzle 8 for dispensing the foaming treatment. The rotary spray head may also include a motor 13 and gears 14 for driving the spray head, in particular if the stream of foam does not generate sufficient pressure to drive the rotating motion, in contrast to, for example, purely liquid flow. In alternative embodiment is, the rotary head may not rotate through multiple revolutions.

Alternatively, the foam dispenser 2 may comprise one or more fixed nozzles for dispensing the foaming treatment.

Alternatively still, the foam dispenser may comprise one or more moving nozzles. For example, the nozzles may be mounted to a spray bar that moves linearly, (or along any other appropriate path) that enables the foam to be coated on the surfaces to be treated.

Preferably, operation of foam dispenser 2 is controlled based on one or more parameter thresholds. Examples of suitable parameters include the concentration of specific gases (e.g., H ₂ S) within the wet well, the concentration of a liquid component of the

wastewater in the wet well, the volume or level of wastewater within the wet well, the pH of the wastewater, visual or olfactory observation of the interior of the wet well, for example inspection of the fat build-up on one or more walls preferably via camera- captured images as described in more detail below.

Additionally or alternatively, the foam dispenser may be controlled by parameter thresholds that activate at preset intervals according to a schedule, and/or based on the time elapsed since the previous treatment cycle etc.

In the most preferred embodiment, the concentration of H ₂ S is measured using an H ₂ S meter 15, and the foam dispenser 2 is activated in response to an H ₂ S measurement which is over a predetermined threshold. Alternatively or additionally, the foam dispenser may be synchronised with other mechanisms of the wastewater component. For example, the foam dispenser may be activated when a pump is activated for emptying the wet well, so that the foam may be sprayed onto substantially dry surfaces. This may be done using level sensors to monitor the level of content in the wet well.

Additionally or alternatively, operation of the foam dispenser 2 may be manually overridden to enable maintenance staff to initiate ad hoc cleaning cycles if required. The override controls may be via a human-machine interface at the controller 9, or via a portable device as discussed above.

The system may additionally comprise at least one camera 11 to allow for visual inspection and/or recording of the interior of the wet well. The camera preferably provides images or videos in real time to a display device which is remote from the wet well. For example, the images may be viewed by the maintenance operator on a portable personal device (e.g., cellphones, desktops, laptops, tablet devices, smartphones, etc.) or via the human-machine interface at controller 9.

The camera 11 may output the images at preset interval to the user, and the user may also be able to control the camera remotely, to obtain images when required. The camera therefore allows for remote visual monitoring of the condition of the wet well and treatment equipment.

A light source 12 will preferably be provided in order to obtain suitably lit images from the camera. The light may be any suitable light source, e.g. a light bulb, a light-emitting diode (LED), etc., and may operate across any of the visible, ultraviolet, and/or infrared range wavelengths, depending on requirements of the camera. In one embodiment, the light source is controllable remotely by the operator. Alternatively, the light source may be synchronised with the camera, for example as a camera flash unit.

In the preferred embodiment as shown in Figures 1 and 2, the camera 11 and the light source 12 are positioned on the foam dispensing unit 2, which, as described above, is preferably mounted on a cover of the wet well. This provides a good vantage point for the camera, allows for easier access to these components for maintenance, and keeps the camera out of the foam trajectory path during dispensing.

Preferably, for each cleaning cycle, the foam dispenser is operated for a period of time, e.g., one minute, sufficient to dispense the foaming treatment onto all internal surfaces of the wet well. The duration of operation may be preset, or may be manually or automatically varied according to the monitored parameter(s) which triggered the cleaning cycle. For example, the length of treatment cycle may vary depending on the concentration of H ₂ S detected.

Additionally, in the preferred embodiment, the composition of the foamable composition may be varied either manually, or automatically, for example according one or more parameter thresholds, such as the parameters described above. This is possible due to the separate storage and separate input of the chemicals into foam generator unit 1, such that each component of the foamable composition is preferably only supplied and mixed when required. This additionally increases the stability of the foam, as it is preferably generated just prior to dispensing.

Alternatively, the foamable composition is pre-mixed and supplied to the foam generator unit 1 to be foamed when required. In this embodiment, only one bulk storage tank may be required for storing the pre-mixed foamable composition. However, for brevity, the following description will refer to two bulk storage tanks 3, 4.

Depending on the relative locations of the bulk storage tanks 3, 4 and the wet well, the chemicals may be fed into the foam generator unit 1 under gravity. Alternatively, the chemicals may be input via a venturi pump or any other suitable electrical, hydraulic or pneumatic pump.

Additionally or alternatively, the chemicals may be fed into a separate mixing tank (not shown in Figure 1, but similar to mixing tank 20 in Figure 3) prior to input into the foam generator unit 1. This may allow for more thorough mixing, and/or an additional controllable step prior to generating the foaming treatment.

Alternatively, mixing may be performed in line, for example through a static mixer, an inline shear mixer, or a tortuous or helical path through the line.

Additionally or alternatively, the system may include a blending unit (not shown in Figure 1, but similar to blending unit 19 in Figure 3), which is preferably controlled by the controller 9, and in turn controls the proportion of chemicals supplied from each of the storage tanks 3, 4. Alternatively, supply of each chemical may be metered directly from the storage tanks.

It will be appreciated that the number of storage tanks, and absence or presence of the mixing tank, blending unit and foam generator will largely depend on the type of foaming agents employed. In one embodiment, bulk storage tanks 3, 4 are located close to the foam generator unit 1 and foam dispenser 2, near or above the wet well 10. These components may be located within an enclosure. Accordingly, it would be convenient for the tanks to be remotely monitored and accessed by maintenance operators for refilling, etc., instead of having to enter the treatment site.

Accordingly, the tanks are preferably able to be monitored remotely. The level of chemicals in each tank may be measured via level sensors, and the data sent to the controller 9, or to other devices as described above. Preferably, the system is also configured to transmit an alarm to the operator when one or more of the tanks reaches a lower threshold or require refilling.

The sensor for monitoring the volume of each bulk storage tank is preferably an ultrasonic sensor 16, which allows for non-contact level sensing. Other examples of suitable monitoring devices include float switches, radar level sensors (guided as well as non-contact), cameras and weight monitoring systems. The filling system may also include sensors for monitoring flow or mass, and valves if required (i.e., if the tanks are not gravity-fed).

Additionally or alternatively, the storage container(s) is/are refillable remotely from the wet well. The containers may be located around or near the wet well, and are accordingly less accessible to maintenance staff.

In the preferred embodiment, the containers may be contained in an enclosure near or enclosing the wet well. Preferably, the containers may be refilled through fill ports 30 in the wall of the enclosure containing the tanks. If the tanks cannot be directly observed during refilling (i.e., if they are behind a wall), the monitoring equipment preferably outputs data to the delivery personnel, for example to a personal device, to enable safe and efficient refilling.

Figure 3 shows the basic components of the treatment system according to another embodiment. In this embodiment, the treatment system involves the use of a thixotropic composition comprising at least one biological agent.

The thixotropic composition may be a gel or colloid comprising the biological agent. The treatment composition preferably undergoes shear thinning before being applied to the interior surfaces of the wet well. The biological agent may be any one or a combination of enzymes, bacteria and bacteriophage, or fungi found to be effective in controlling the production of toxic gas, and/or controlling the formation and development of biofilms. The biological agent may additionally or alternatively be suitable components of the relevant microorganism, such as the endospores of bacteria, spores of fungi, etc.

Thixotropy refers to the material property of certain gels or fluids that are viscous under static conditions but become less viscous over time when shaken, mixed, or otherwise sheared (i.e., undergoes shear thinning). The fluids return to a more viscous state after a fixed time.

The thixotropic composition is preferably chosen so that it can be adequately thinned prior to dispensing via, for example, a spray head. Once the composition has been sprayed onto the surfaces of the wet well, it preferably returns to a more viscous state so that it will cling to and persist on the surfaces of the wet well.

The thixotropic composition may be thinned via various mechanisms, for example, due to the pressure of a pump, the passage of the composition through a spray head and/or a specific mixer which applies shear force to the composition.

In one embodiment, as shown in Figure 3, the system comprises a pump 18 which applies pressure to the thixotropic composition to shear thin the composition prior to dispensing. The pump may be a double diaphragm pump, or any other pump suitable for the viscous fluid.

The pump 18 (or other means of shear thinning the composition) may be controlled by the controller 9', to vary the viscosity of the treatment by varying the duration of shear thinning of the composition and/or varying the amount of pressure or shear force applied to the composition.

The embodiment shown in Figure 3 also comprises a blending unit 19 and a mixing tank 20 for mixing the components of the treatment composition supplied from bulk storage tanks 24, 25.

In the preferred embodiment, the thixotropic composition comprises a thixotropic carrier having the desired thixotropic flow behaviour. The thixotropic carrier may comprise a thickener such as carboxymethyl cellulose (CMC), other natural or synthetic gums, fumed silica, or rheology modifiers such as polymers, salts, saccarides or other suitable chemical reactions. The carrier may additionally or alternatively be a binary polymer system.

In one embodiment, the thixotropic treatment may be a single composition comprising the biological agent(s) pre-mixed into the thixotropic carrier.

Alternatively, if the carrier comprises a plurality of components, these components may be stored separately in different bulk storage tanks 24, 25, and fed to the dispensing unit 21 via separate feed lines. This allows for the concentration of each component to be varied either manually or automatically, for example according to one or more parameter thresholds as described above.

Similarly to the foaming treatment embodiment described above, the ability to control and customise the composition of the treatment on demand increases the flexibility and effectiveness of the treatment regime. For example, viscosity of the treatment may be varied in response to the level of hydrogen sulfide detected in the wet well. Additionally, the ability to prepare the treatment on-demand may promote the stability of the treatment composition.

The blending unit 19 is preferably controlled by the controller 9', and in turn controls the proportion of chemicals supplied from each of the storage tanks 24, 25. Alternatively, supply of each chemical may be metered directly from the storage tanks.

The composition may then be mixed in mixing tank 20 to form the thixotropic carrier. Alternatively, mixing may be performed in line, for example through a static mixer, an inline shear mixer, or a tortuous or helical path through the line.

The biological agent may be added at any suitable stage in the process prior to dispensing. In one example, the composition in one of the storage tanks 24 or 25 may comprise the biological agent.

In another example, the biological agent may be fed into the line prior to, during or after mixing of the components of the carrier.

In the embodiment where the thixotropic treatment is pre-mixed with the biological agent, the treatment composition may be fed directly into the dispenser unit 21, so that blending unit 19 and mixing tank 20 may not be required. In any case, the bulk storage tank(s) may be monitored remotely as discussed above, so that maintenance staff need not enter the treatment site.

Additionally or alternatively, the bulk storage tank(s) may be refilled remotely from the treatment site. In one embodiment, the storage tank(s) may be refilled through fill ports in a wall of an enclosure containing the tanks, also as described above.

In the preferred embodiment, the treatment dispenser unit 21 comprises a rotary spray head 22 having at least one spray nozzle 23 for dispensing the thixotropic treatment. Similar to the first embodiment of the treatment system, the operation of the treatment dispenser unit 21 may be controlled based on one or more parameter thresholds (such as one or more the of the parameters described above in relation to the foaming treatment system).

It will be appreciated that the number of storage tanks, and absence or presence of the mixing tank and blending unit will largely depend on the type of treatment composition employed.

The other components of the treatment system of the second embodiment shown in Figure 3 are preferably identical to, or very similar to, the components of the treatment system of the first embodiment shown in Figure 1, and accordingly will not be discussed in further detail.

The foregoing description of the invention includes preferred forms thereof. Modifications may be made thereto without departing from the scope of the invention as defined by the accompanying claims.