NZ795941B2 - Systems and Methods for Removing Volatile Compounds from Water-Storage Tanks - Google Patents

Abstract

method of removing volatile chemicals from water stored in a water-storage tank, comprising: conveying at least a portion of water stored in the water-storage tank from a location below a surface of the water up to the surface of the water with a water conveyance device that is completely submerged when the water conveyance device is in use; directing air from an exterior of the water-storage tank non-perpendicularly to the surface of the water stored in the water-storage tank with an active air ventilation device; and exchanging the exterior air with air in an interior of the water-storage tank through a port located above the surface of the water, thereby removing at least a portion of volatile organic compounds present in the stored water of the water-storage tank, wherein the water-storage tank comprises a tank containing the water, a roof positioned over the tank, and a headspace region formed between the roof and a surface of the water contained in the tank, and wherein the method comprises directing air from the exterior of the water-storage tank into the headspace region non-perpendicularly to the surface of the water with the active air ventilation device, and wherein the active air ventilation device is attached to the roof of the water-storage tank such that exterior air exits the active air ventilation device directly into the headspace region that is above the surface of the water.

Description

A method of removing le chemicals from water stored in a water-storage tank, comprising: conveying at least a n of water stored in the water-storage tank from a location below a surface of the water up to the surface of the water with a water conveyance device that is completely ged when the water conveyance device is in use; ing air from an exterior of the water-storage tank non-perpendicularly to the surface of the water stored in the waterstorage tank with an active air ventilation device; and exchanging the or air with air in an interior of the water-storage tank through a port located above the surface of the water, thereby removing at least a portion of volatile organic compounds present in the stored water of the water-storage tank, wherein the water-storage tank comprises a tank containing the water, a roof oned over the tank, and a headspace region formed between the roof and a surface of the water contained in the tank, and wherein the method comprises directing air from the exterior of the water-storage tank into the headspace region non-perpendicularly to the surface of the water with the active air ventilation device, and wherein the active air ventilation device is attached to the roof of the water-storage tank such that exterior air exits the active air ventilation device directly into the headspace region that is above the surface of the water. 795941 B2 W0 20182’126100 S AND S FOR REMOVING VOLATILE COMPOUNDS FROM WATER-STORAGE TANKS CROSS REFERENCE TO RELATED APPLICATIONS This application claims the bene?t of United States Provisional Application No. 62/441,208, ?led December 31, 2016, which is incorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION Field of the Invention The present invention is directed to s and methods for reducing the amount of volatile organic compounds, such as trihalomethanes and other volatile contaminants t in water-storage tanks.

Description of Related Art Water delivered to humans, animals, and for agricultural uses is ed to be healthful. As such, it is desirable to remove contaminants such as volatile organic compounds ("VOCs") from water systems prior to delivery to the consumers. Removal of such contaminants, especially trace amounts of such contaminants, can be problematic, however.

Moreover, with the sed adoption of secondary disinfection regimes, downstream generation of volatile contaminates can occur in a municipal water supply, even when the water might have substantially lower concentrations of such materials at the time the water left the water treatment facility. By—products of secondary disinfection regimes, namely trihalomethanes ("THMs"), can be generated prior to delivery of the water to a er. Given the increased potential for volatile materials to occur in water systems today, alternative methods to reduce disinfection by—products in water systems have been proposed.

One method for reducing disinfection by-products is to reduce l organic matter via treatment processes at the water treatment plant prior to chlorination of a water .

However, it is not always cost effective to eliminate all l organic matter in a water supply and, sometimes, the speci?c con?guration of a water system can allow l organic matter to be introduced downstream of a treatment plant. Water derived from wells or aquifers may also be dif?cult to treat to remove natural organic matter in the ?rst instance.

Another method for reducing disinfection by—product levels is to reduce or eliminate disinfection by—products that have been formed and that are present in a water supply system prior to delivery of water to a customer. In this regard, aeration has emerged as a method to remove disinfection by—products, as well as other le materials in water supplies, while the W0 20182’126100 water is in situ in a distribution system, that is, stored in a water—storage container. on practiced in distribution systems has been shown to be cost ive when compared to making major changes in treatment processes or alternate disinfection practices. Brooke, Ethan and Collins, M. Robin, l—American Water Works Association, Issue Date: Oct. 2011, vol. 103, No. 10, pgs. 84-96.

Separation of volatile als Via aeration is accomplished by increasing the surface area of the water exposed to air. As applied to water-storage tanks, increased surface area is typically achieved by way of droplet creation. However, aeration can be less effective under certain conditions that are common in water-storage tanks. For example, the ef?ciency of aeration systems relates to the headspace volume, with reduced headspace volume generally corresponding to reduced ef?ciency in that aeration systems need both unsaturated air that can accept volatiles from the water and a suf?cient distance between the nozzle and the water surface to effect suf?cient aeration et creation).

Thus, it is desirable to provide a water system that can suf?ciently remove volatile inants from water-storage tanks without any of the previously described drawbacks.

SUMMARY OF THE INVENTION In certain miting embodiments or aspects, the present invention is directed to a system for reducing an amount of volatile organic compounds comprising: a water—storage tank comprising a tank containing water, a roof positioned over the tank, and a headspace region formed n the roof and a surface of the water contained in the tank; an air exchange system positioned at least partially in the headspace region that is con?gured to exchange air exterior to the tank with air inside the tank; and a water conveyance deVice located at least partially in the water of the water-storage tank and which is con?gured to convey water in a manner that produces a surface ?ow velocity.

In some non-limiting embodiments or aspects, the water ance device is con?gured to convey water to the water e. Further, the water conveyance device can be con?gured to exchange water at or toward the ?oor of the tank with water at or toward the water surface. The water conveyance device can also circulate water around the tank.

] In certain miting embodiments or aspects, the water conveyance device is tely submerged in the water when the tank is in use. For instance, the water conveyance device can be attached to or sit on the ?oor of the tank.

In some miting embodiments or aspects, the air exchange system comprises: (i) a port that enables air to ?ow out of the water-storage tank; and (ii) an active air ventilation device con?gured to facilitate movement of air exterior of the water-storage tank into the headspace region. The active air ventilation device can be con?gured to facilitate the movement of air or ofthe water-storage tank into the headspace region in a direction that is non-perpendicular to the water surface. The active air ventilation device can also be red to facilitate the movement of air exterior of the water—storage tank into the headspace region substantially across the water surface.

In certain miting embodiments or aspects, the active air ventilation device comprises air vents that ?uidly connect the air exterior of the water-storage tank to the headspace region. In such embodiments or aspects, the active air ventilation device can se at least one screen that is positioned over at least one of the air vents. In some miting embodiments or aspects, the active air ventilation device comprises an air moving device, such as a fan for example. In n non-limiting embodiments or aspects, the water conveyance device comprises a mixer having blades, such as an impeller for example.

The present invention also includes a method ofremoving volatile materials from water stored in a water-storage tank. In certain non-limiting embodiments or s, the method comprises: conveying at least a portion of the water stored in the water—storage tank from a location below a surface of the water up to the surface of the water with a water conveyance device; directing air from the exterior of the water-storage tank non-perpendicularly to the surface ofthe water stored in the water-storage tank with an active air ventilation device; and exchanging the exterior air with air in the interior of the storage tank through a port d above the surface of the water, thereby removing at least a portion of volatile organic compounds present in the stored water of the storage tank.

In some non-limiting embodiments or aspects, the water conveyance device maintains a chemical nt between the exterior air and the water such that le compounds are transferred from the water to the interior air. The exchanging of the air can comprise operating an air moving device of the active air ventilation device engaged with the water- storage tank to move the exterior air into the water-storage tank in a direction substantially across the surface of the water. r, in some non-limiting embodiments or aspects, the method does not incorporate an aeration step. In certain non-limiting embodiments or aspects, the stored water contains an amount of le als and the method automatically initiates when the amount of volatile chemicals in the stored water exceeds a pre—deterrnined amount. The method can also automatically stop when the amount of volatile chemicals in the stored water drops below the pre—deterrnined amount. The water stored in the water-storage tank can further WO 26100 2017/068885 comprise an initial amount of volatile chemicals and the pre-determined amount is about 5% of the initial amount.

Further non—limiting embodiments or aspects are set forth in the following clauses: Clause 1: A system for reducing an amount of le organic compounds comprising: a water—storage tank comprising a tank containing water, a roof positioned over the tank, and a headspace region formed between the roof and a surface of the water contained in the tank; an air exchange system positioned at least lly in the headspace region that is red to exchange air exterior to the tank with air inside the tank; and a water conveyance device located at least partially in the water of the water-storage tank and Which is con?gured to convey water in a manner that produces a surface ?ow velocity.

Clause 2: The system of clause 1, wherein the water conveyance device is con?gured to convey water to the water surface.

Clause 3: The system of clauses l or 2, wherein the tank has a ?oor and the water conveyance device is con?gured to exchange water at or toward the ?oor of the tank with water at or toward the water surface.

Clause 4: The system of any of clauses 1-3, wherein the water conveyance device circulates water around the tank.

Clause 5: The system of any of s 1-4, wherein the water conveyance device is completely submerged in the water when the tank is in use.

Clause 6: The system of any of clauses 1-5, wherein the water conveyance device is ed to or sits upon the ?oor of the tank.

Clause 7: The system of any of s 1-6, wherein the air exchange system comprises: (i) a port that enables air to ?ow out of the water-storage tank; and (ii) an active air ventilation device con?gured to tate movement of air or of the water-storage tank into the headspace region.

Clause 8: The system of any of clauses 1-7, wherein the active air ventilation device is con?gured to facilitate the movement of air exterior of the water-storage tank into the headspace region in a direction that is non—perpendicular to the water surface.

Clause 9: The system of any of clauses 1-8, wherein the active air ventilation device is con?gured to facilitate the movement of air exterior of the water-storage tank into the headspace region substantially across the water surface.

Clause 10: The system of any of clauses 1-9, wherein the active air ventilation device comprises air vents that ?uidly connect the air exterior of the water—storage tank to the headspace region.

Clause 11: The system of any of clauses 1-10, wherein the active air ventilation device comprises at least one screen that is positioned over at least one of the air vents.

Clause 12: The system of any of clauses 1-11, wherein the active ventilation device comprises an air moving device.

Clause 13: The system of any of clauses 1—12, wherein the air moving device is a fan.

Clause 14: The system of any of clauses 1-13, wherein the water conveyance device comprises a mixer having blades.

Clause 15: A method of ng volatile materials from water stored in a water- storage tank, comprising: ing at least a portion of the water stored in the water-storage tank from a location below a e of the water up to the surface of the water with a water conveyance device; directing air from exterior of the water-storage tank non-perpendicularly to the surface of the water stored in the water-storage tank with an active air ventilation device; and ging the exterior air with air in an interior of the water-storage tank through a port d above the surface ofthe water, thereby removing at least a n of volatile c compounds present in the stored water of the water-storage tank.

Clause 16: The method of clause 15, wherein the water conveyance device ins a chemical gradient between the exterior air and the water such that volatile compounds are transferred from the water to the interior air.

Clause 17: The method of clauses 15 or 16, wherein the exchanging of the air comprises operating an air moving device of the active air ventilation device engaged with the water- storage tank to move the or air into the water- storage tank in a direction substantially across the surface of the water.

Clause 18: The method of any of clauses 15—17, wherein the method does not incorporate an on step.

Clause 19: The method of any of clauses 15-18, wherein the stored water contains an amount of volatile chemicals and the method automatically initiates when the amount of volatile chemicals in the stored water exceeds a pre-determined amount.

Clause 20: The method ofany of clauses 15-19, wherein the method tically stops when the amount of volatile chemicals in the stored water drops below the pre-determined amount.

W0 20182’126100 Clause 21: The method of any of clauses 15-20, wherein the water stored in the container comprises an initial amount of volatile chemicals and the pre-determined amount is about 5% of the initial amount.

BRIEF DESCRIPTION OF THE DRAWINGS is a partial front View of a roof portion of a water-storage tank having a VOC removal system according to a non-limiting embodiment of the invention; and is across-sectional front View ofan active air ventilation system of PTION OF THE INVENTION For purposes of the following detailed ption, it is to be understood that the invention may assume various ative variations and step sequences, except where expressly speci?ed to the contrary. Moreover, other than in any operating examples, or where otherwise indicated, all numbers expressing, for example, quantities used in the speci?cation and claims are to be tood as being modi?ed in all instances by the term "about". Accordingly, unless indicated to the contrary, the cal parameters set forth in the following speci?cation and attached claims are approximations that may vary ing upon the desired properties to be obtained by the present invention. At the very least, and not as an attempt to limit the application of the doctrine of lents to the scope ofthe claims, each numerical parameter should at least be construed in light of the number of ed signi?cant digits and by applying ry rounding techniques. hstanding that the numerical ranges and parameters setting forth the broad scope of the invention are approximations, the numerical values set forth in the speci?c examples are reported as precisely as possible. Any numerical value, however, inherently contains certain errors necessarily resulting from the standard variation found in their tive testing measurements.

Also, it should be understood that any numerical range recited herein is ed to include all sub-ranges subsumed therein. For example, a range of "1 to 10" is intended to include all sub-ranges between (and including) the recited minimum value of 1 and the recited maximum value of 10, that is, having a minimum value equal to or greater than 1 and a maximum value of equal to or less than 10.

Further, the terms "upper," ," "right," "left," "vertical," "horizontal," "top," "bottom," "lateral," "longitudinal," and derivatives thereof shall relate to the ion as it is oriented in the drawing ?gures. However, it is to be understood that the invention may assume alternative variations and step sequences, except where expressly speci?ed to the ry. It is also to be understood that the speci?c devices and processes illustrated in the attached drawings, and described in the speci?cation, are simply exemplary embodiments or aspects ofthe invention.

Hence, speci?c dimensions and other physical characteristics related to the embodiments or s disclosed herein are not to be considered as limiting.

In this application, the use of the singular includes the plural and plural encompasses singular, unless speci?cally stated ise. In addition, in this application, the use of "or" means "and/or" unless speci?cally stated otherwise, even though "and/or" may be itly used in certain instances.

The term "substantially" is meant to permit ions from the descriptive term that do not negatively impact the intended purpose.

The phrase "volatile chemical" includes VOCs such as chloroform, orrn, and oroethylene (TCE), as well as radon, carbon dioxide, and hydrogen sul?de. Embodiments or aspects according to this disclosure may at least partially remove one, some or all ofthe volatile chemicals present in the water stored in the water-storage tank regardless of whether the description refers to volatile chemicals lly or certain volatile als speci?cally. The term "VOCS" as used herein es VOCs and other volatile chemicals and such terms are used interchangeably herein.

The phrases "water—storage tanks", "water—storage containers" and the like are used interchangeably. In on, the term "water" when used to describe "water-storage tanks/containers" encompasses both water and compositions comprising water, in which water is the majority of the composition.

The term "community water supply" means a water supply provided from a central point and piped to individual users under pressure. Water sources used to generate municipal water supplies can vary. As required by regulations, municipal water supplies will typically undergo primary disinfection at a treatment facility to make the water suitable for use as potable water or the like. Secondary disinfection with chloramination processes can also be provided at the water treatment plant to ensure that the water Will remain suitable for use as it s through the water bution system to the consumer.

"Well water" is water obtained from a below-ground water source such as an aquifer, and that is stored (or storable) for supply as potable water, among other uses. As would be recognized, well water can natively comprise free ammonia as a result of l processes. Well water may be disinfected prior to use, or it may not be.

"Primary ectants" are generally intended to kill or otherwise deactivate pathogens that exist in a water source upon its arrival at a ent plant, whereas "secondary disinfectants" are generally intended to maintain the healthiness and cleanliness of the water supply upon leaving the treatment plant throughout its path through a community water system until it reaches the faucet of a consumer. "Secondary disinfection" may be for the maintenance of free or ed chlorine levels in a water supply once the water is treated with primary disinfecting methods (e.g., sedimentation, coagulation, UV, chlorine gas, etc.).

As indicated, the present invention includes systems and methods for removing or reducing the amount of one or more le contaminants from water that is stored in a water- storage tank prior to delivery of such water to a consumer. The stored water can se, for example, water that has been treated with secondary disinfection at a water treatment facility, and/or the stored water can comprise another source of water, such as a well or an aquifer.

Although the methods and systems herein substantially do not rely on increasing the surface area of the water undergoing amination for ef?cacy, the systems and methods herein may be used together with approaches for removing contaminants, which rely on increasing the surface area of water. The systems and methods generally involve circulating or ise ing stored water within the water—storage tank while also exchanging air outside the tank for air inside the tank.

Without being bound by theory, it is believed that the movement of water coupled with the exchange of interior air with exterior air maintains or increases the chemical potential between the water surface and the air to favor release of volatile als into the air. As used herein, the "chemical potential" refers to the tendency for the chemical to diffuse. In some non-limiting embodiments or aspects, the systems generally comprise a water-storage tank ?tted with a device for circulating water in addition to a device for actively ating air inside the ace of the water-storage tank and for actively exchanging inside air with outside air (i.e. actively venting air).

Referring to and in certain non-limiting embodiments or aspects, the present invention es a system 1 for removing volatile compounds from a water-storage tank 10.

The system 1 includes a storage tank 10 ?tted (or retro?tted) with an air exchange system and a water conveyance device 50. also illustrates air ?ow patterns 6 and water ?ow patterns 8 within the water-storage tank 10 when the air exchange system 30 and water conveyance device 50 are active.

In some non-limiting embodiments or aspects, the water-storage tank 10 is a community water-storage tank 10. Community water-storage tanks typically have a capacity of about 500 gallons ofwater or greater, or about 1,000 gallons ofwater or greater, or about 100,000 gallons of water or greater, or about 000 gallons of water or greater. Water-storage tanks may even have capacities of up to a billion gallons of water. The systems and methods of the present invention are typically for use with large volume water-storage tanks, i.e. water-storage tanks having a volume of about 5,000 gallons or greater. Water-storage tanks can e elevated ners and other substantially enclosed containers in which these large volumes of water can be stored prior to delivery to a customer.

In use, a portion ofthe capacity ofthe water—storage tank 10 is "headspace" 12, a region, which does not contain water. The ace 12 is ore formed between the interior surface 16 of the roof 14 of the water—storage tank 10 and the surface 18 of a body of water 20 ned in the water-storage tank 10. As used herein, the surface 18 of a body of water 20 is also referred to as the air/water interface. Further, it is appreciated that the volume of headspace 12 tes in relation to the amount of the body of water 20 stored in the water-storage tank 10.

As indicated, the water-storage tank 10 comprises an air exchange system 30 and a water conveyance device 50. The air exchange system 30 circulates air within the headspace region 12 and exchanges air interior to the water-storage tank 10 with air exterior to the water- storage tank 10. Referring to the air exchange system 30 ses a port 32 and an active air ation device 34, both of which, for example, can be formed h the roof 14 of the water—storage tank 10 and are in ?uid ication with the headspace region 12.

In some non-limiting embodiments or aspects, the port 32 is typical of water-storage tanks 10 for which the level of water ?uctuates (for example, to prevent de—pressurization and buckling of the water-storage tank 10 structure during draining). It is appreciated that the port 32 enables air to ?ow out of the storage tank 10.

As previously described, the air exchange system 30 also comprises an active air ventilation device 34. further illustrates a non-limiting embodiment of an active air ventilation device 34. As shown in air movement is provided by a fan or other air moving device 36. Air ?ow direction through the active air ventilation device 34 may be accomplished by appropriate orientation of the air moving device 36 and/or by using a de?ector 38 in ?uid communication with the air moving device 36. The use of a de?ector 38 may be particularly desirable where the air?ow direction is otherwise perpendicular to the water e, for example to optimize removal of volatile compounds and/or minimize surface water disruptions. As such, the air moving device 36 can in?uence air?ow rate and frequency, and the optional de?ector 38 can help in?uence air?ow direction. It is appreciated that the active air ventilation device 34 is con?gured to facilitate exchange of air exterior 40 to the water-storage tank 10 with air interior to the water-storage tank 10 by ?uidly connecting the interior headspace region 12 with the exterior environment by way of vents 42.

To alleviate and/or prevent ination ofwater stored within the water-storage tank , for example to alleviate or prevent s of animals, leaves, and/or other debris into the water—storage tank 10, screens 44 may be provided to cover the vents 42. In addition, and as indicated above, the ventilation device 34 is an "active" air ventilation device 34, and accordingly, es input energy (e.g. mechanical or electrical) to assist the air exchange process. Referring to the input energy is provided by the air moving device 36 such as a fan. In some miting embodiments or aspects, for e, where there may be a desire to achieve additional energy savings, a switch may be provided that automatically engages the air moving device 36 when the amount of volatile compounds or volatile compound concentration is above a predetermined amount, and/or automatically disengages the air moving device 36 when the amount of volatile compounds or the volatile compound concentration is below a predetermined amount. In some examples, the water stored in the water-storage tank 10 comprises an l amount of le chemicals and the predetermined amount is about 5% of the initial amount, about 10% of the initial amount, about 15% of the initial amount, or about % of the initial amount.

It is appreciated that the air moving device 36 speci?cations, and the dimensions of the air ventilation device 34, including the relative dimensions of the air ventilation device 34 as compared to the air moving device 36, determine the air?ow rate (or range of air ?ow rates).

Also, the angle of the active air ventilation device 34 connected to the water-storage tank 10 relative the surface 18 of the body of water 20 de?ning the lower boundary of the headspace 12 will also impact air ?ow direction. Although the active air ation device 34 is shown mounted on the roof 14, the active air ventilation device 34 can be connected to other areas of the water-storage tank 10 such as, for e, being ducted from the .

In some non-limiting embodiments or aspects, the components that make up the air exchange system 30 can include the devices described in US. Patent No. 716, ?led Dec. 13, 2013, which is hereby orated by reference in its entirety.

In general, and without being bound by theory, it is ed that the ef?ciency of volatile chemical removal will be dependent, in part, on the velocity and direction of air contact at the ter interface 18. In some non-limiting embodiments or aspects, the active air ventilation device 34 is con?gured to move air into and around the water-storage tank 10 in a direction and/or velocity that optimizes removal of air laden with inants, such as VOCs.

For instance, the active air ventilation device 34 can be con?gured to move air into the water- e tank 10 in a direction that is non-perpendicular to the water surface 18 de?ning the boundary of the headspace region 12. In certain non-limiting embodiments or aspects, the active air ventilation device 34 is con?gured to move air substantially laterally across the interior surface 16 of the roof 14 of the storage tank 10. Further, in some non-limiting embodiments or aspects, the active air ventilation device 34 is con?gured to move air substantially laterally across the water surface 18 g the boundary of the headspace region 12. In addition, the active air ventilation device 34 can be con?gured to move air in a direction and/or ty substantially without generation of suf?cient surface waves and/or splashes (hereafter "surface disruptions") to create any appreciable additional surface area at the air/water ace 18. The active air ventilation device 34 is also con?gured to direct the volatile chemicals away from the water surface 18 and toward the port 32 to facilitate their removal from the water-storage tank 10.

In some non-limiting embodiments or aspects, the air exchange system 30 is con?gured to achieve a suf?cient number of air exchanges/day corresponding to maintaining a d chemical potential across the ter interface and a desired rate of removal ofVOC. In certain non-limiting embodiments or s, the air exchange system 30 is con?gured to exchange air through the water-storage tank 10 at a rate several times faster than the movement of water in and out of the water-storage tank 10. In some examples, the air exchange system 30 can accomplish at least approximately 5-100 air ges/day.

As previously described, and as shown in the VOC removal system 1 also includes a water conveyance device 50 (also referred to herein as a "mixer") in operational engagement with the body of water 20 in the water-storage tank 10 for moving the water 20 throughout the water-storage tank 10. The conveyance device 50 is red to move at least a portion of the stored water 20 up to the water surface 18, such that at least some of the conveyed water comes into contact with air that is supplied from the air exchange system 30 forming an air/conveyed water ace.

In some non-limiting embodiments or aspects, the water conveyance device 50 can be substantially immersed below the water e 18, such that circulation of the water with the conveyance device 50 will substantially not result in the generation of surface disruptions and additional appreciable surface area at the water e 18. The water conveyance device 50 is also con?gurable to substantially not generate formation of bubbles at the water surface 18. In n non-limiting embodiments or aspects, the water conveyance device 50 includes mixing blades 52 (such as an impeller for example) and is maintained at a distance below the surface 18 of the stored water in which the blade(s) 52 of the water ance device 50 are fully submerged.

As shown in the water conveyance device 50 can be located within the water— storage tank 10 so that it is completely submerged in the body of water 20. However, the water conveyance device 50 need not be ?llly ged as long as the water conveyance device 50, when in operation, facilitates the movement of the body ofwater 20 within the water—storage tank , preferably without ntially generating surface disruptions and additional iable e area at the water surface 18. In some non-limiting embodiments or aspects, the water conveyance device 50 (or at least the portion of the water conveyance device 50 that may cause surface disruptions and increased water surface area) is fully submerged at least about 36 inches beneath the water surface 18 to reduce or eliminate surface disruptions and increased water surface area. Further, in certain non-limiting embodiments or aspects, the water conveyance device 50 can be con?gured to exchange water at or toward the ?oor 11 of the water—storage tank with water at or toward the water surface 18. The water conveyance device 50 can also be attached to or sit upon the ?oor 11 of the storage tank 10.

In some non-limiting embodiments or aspects, the water conveyance device 50 will continuously or substantially continuously convey stored water 20 from below the water surface 18 to the water surface 18 (that is, the air/water interface) when the water conveyance device 50 is ional. In certain non-limiting embodiments or aspects, including the illustrated water ?ow pattern 8 water of water is circulated around the tank water-storage 10 in a top to bottom con?guration.

Without being bound by , it is believed that the ncy ofvolatile contaminant removal depends, in part, on the frequency that new air/ water interfaces are generated or, put another way, how much turnover of water is created. In some non—limiting ments or aspects, the water conveyance device 50 is con?gured to result in circulating the entire volume of water 20 in the water-storage tank 10 at least once, at least six times, at least 10 times, at least 50 times, or at least 100 times during a ?ll and drain cycle in the water-storage tank 10. The volatile compound removal may be increased by increasing the circulation rate beyond the set number of exchanges per ?ll and drain cycle.

The air exchange system 30 and water ance device 50 can use a power source for operation thereof. The power source can be provided by any method known in the art. For example, the power source can be provided by connection ofthe water-storage tank 10 to a power grid. Yet ?lrther, the water-storage tank 10 can be powered by batteries. Still ?thher, power can be provided by solar panels. In addition, the power for the system may be supplied by water pressure present in the distribution system, or by pumps.

In operation, the air exchange system 30 and the water conveyance device 50 cooperate to exhaust at least a portion of the VOCs present in the stored water 20 to the outside air. Without wishing to be bound by theory, it is ed that the air exchange system 30 and the water conveyance device 50 cooperate to in a chemical gradient between the air and the water.

More speci?cally, the water conveyance device 50 and air exchange system 30 cooperate to maintain a concentration difference between the water and the air ofthe constituent to be removed such that there is a al potential between the water and the air that favors the transport of the constituent out of the water and into the air.

Thus, for example, in operation, the air ge system 30 and the water conveyance device 50 produce torroidal air ?ow and water ?ow patterns 6,8 tively. Depending on the 3D geometry, the ?ow patterns may be concurrent, oblique or counter-current (depending on where the axis of each ?ow is located and reference point of view). Referring to and when shown in cross—section, the air and water ?ow patterns 6, 8 are counter-current to each other (e.g. the air ?ow pattern 6 is clockwise h the ace 12, whereas the water ?ow pattern 8 is counterclockwise around the water—storage tank 10) resulting in air and water ?ow 6, 8 in the same direction at the air/water interface 18.

As further shown in the air ?ow pattern 6 of the air exchange system 30 conveys a source of air having a relatively low content of VOCs (i.e. a lower content than the air inside the storage tank 10, or inside the water-storage tank 10 at the air/water interface 18), for e outside air 40, into the water-storage tank 10 via the active air ventilation device 34, across the surface of water 18 and back out h the port 32. In some non-limiting embodiments or aspects, air can also be exhausted to the exterior through the active air ventilation device 34. In this way, air inside the water-storage tank 10 having a relatively higher VOC concentration, for example at the air/water interface 18, is removed from the water-storage tank and replaced with air, for example exterior air 40, having a relatively lower concentration of VOCs.

Similarly, and as also shown in the water ?ow pattern 8 of the water ance device 50 circulates water from beneath the water surface 18, for e from the bottom of the storage tank 10, across the water surface 18 and back down beneath the water surface18 (e. g. back down to the bottom of the water-storage tank 10). In this way, water having a relatively lower concentration of VOCs (due to the VOCs moving out of the water into the air as a result of the al potential difference), for example, water at the air/water interface 18, is replaced with water, for example water at the bottom of the water—storage tank 10, having a relatively higher concentration of VOCs.

Referring to which includes an exhaust port 32, volatile chemicals present in the headspace region 12 are desirably removed therefrom, so as to prevent the volatile chemicals from being reintegrated into the stored water 20, as well as to reduce the possibility that the headspace region 12 becomes saturated with the volatile chemicals. In some non- limiting embodiments or s, saturation of the headspace region 12 can reduce the ability for additional volatile chemicals to be ef?ciently removed from the stored water 20. Thus, it can be desirable to remove volatile chemicals from the headspace region 12 after such volatile chemicals are removed from the stored water 20. In this regard, the at least one exhaust port 32 is operational to convey air in the ace region 12 to a location outside of the water- storage tank 10.

In certain non-limiting embodiments or aspects, the air application step will substantially not result in an increase in the surface area of the water, as is the intention of existing methodologies whereby volatile materials are removed from water via prior art air stripping methods used to remove volatile materials from water. In this regard, when the water- storage tank 10 is circular in cross—section, the conveyed water portion has a conveyed water portion surface area de?ned by the on: A = TIT'Z, wherein r is a water-storage tank 10 interior radius de?ned by 1/2 of the diameter of a top surface of the stored water 20. r, the surface area of the conveyed water present at the air/water interface 18 when air is being d thereto is ntially equivalent to the surface area of the ter interface 18 when no air is being applied thereto, where the volume of the stored water 20 is equivalent before and during air application. In other words, for an equivalent volume of water that has the same radius de?ned by the portion of the water-storage tank 10 that the interface 18 meets, the amount of e water 18 that is in contact with the ace region 12 will be substantially the same.

It is appreciated that the air exchange system 30 and water conveyance device 50 are not limited to the speci?c illustrated embodiments or s described . For example, they are not limited to an active air ventilation device 34 that moves e air 40 across the surface of the water or to a water conveyance device 50 that circulates water from the bottom of the water-storage tank 10 across the water surface and back. Other air exchange systems 30 and water conveyance devices 50 which can tate maintaining a chemical potential between the water and the air that favors transport of one or more volatile chemicals out of the water and into the air is within scope of the present invention. Thus, for e, included within the scope of this disclosure are other water conveyance devices 50 that will continuously, or substantially continuously, refresh the water at the air/water interface 18 by recirculation, thereby providing new ter interfaces 18, and other air exchange systems 30 that will act to remove or reduce the amount of volatile als present at or near the air/water interface Even in instances where very little volatile chemicals are likely present each time a new volume of conveyed water having a concentration of volatile chemicals comes into contact with air having a lower concentration of volatile contaminants at the air/water interface 18, at least some of the volatiles will be removed at any one time. As the water continues to be exchanged, for example re-circulated, in the water-storage tank 10, water with sed concentration of volatile chemicals may be presented at the air/water interface 18 relative to the water it replaced, thus providing additional contact with the exchanged/refreshed air having a lower concentration of volatile compounds than the air it replaced and the new water it contacts at the air/water interface 18, which, in turn, will result in ?irther removal of volatile chemicals from the water supply. Over time, a substantial volume of the stored water in the water— storage tank 10 will have the opportunity to come into t with the supplied air, thus resulting in a low concentration of volatile chemicals in the water— storage tank 10, as compared to a stored water supply 20 from the same source that is not subjected to the methodology described herein.

In certain miting embodiments or aspects, the ive methodology es a level of les chemicals in the stored water supply 20 that is about 1% less, or about 5% less, or about 10% less, or even up to about 50%, 55%, 60%, 65%, and 68% less than a stored water supply 20 that is not subjected to the methodology described herein. The amount of volatile chemical ion can depend on the cross-sectional size of the water-storage tank 10 at the air/water interface 18 and detention time.

In some non-limiting embodiments or aspects, the systems and methods herein provide signi?cant bene?ts over other existing volatile chemical l methodologies. For example, the ive methodology utilizes substantially less energy than aeration volatile removal technologies. Since water— e tanks 10 are often in locations Where it is dif?cult to provide a continuous source ofpower, the low energy aspect of the present invention is an improvement.

As another example, the inventive systems and methods substantially reduce the amount of air uced into the water, with an attendant reduction in the possibility that dissolved gases resulting from vigorous aeration (as is ed to generate satisfactory volatile removal) will affect the pH and/or alkalinity of the water.

Whereas ular embodiments or aspects of this invention have been described above for purposes of illustration, it Will be evident to those skilled in the art that numerous variations of the s of the present invention may be made Without departing from the invention as de?ned in the appended claims.

Claims (14)

THE INVENTION CLAIMED IS

1. A method of removing volatile chemicals from water stored in a water-storage tank, comprising: conveying at least a portion of water stored in the water-storage tank from a location below a surface of the water up to the surface of the water with a water conveyance device that is completely submerged when the water conveyance device is in use; ing air from an exterior of the water-storage tank non-perpendicularly to the surface of the water stored in the water-storage tank with an active air ventilation device; and exchanging the exterior air with air in an interior of the water-storage tank through a port located above the surface of the water, thereby removing at least a n of le c compounds present in the stored water of the water-storage tank, n the water-storage tank comprises a tank containing the water, a roof positioned over the tank, and a headspace region formed between the roof and a surface of the water contained in the tank, and wherein the method comprises directing air from the exterior of the water-storage tank into the headspace region nonperpendicularly to the surface of the water with the active air ventilation device, and wherein the active air ventilation device is ed to the roof of the storage tank such that exterior air exits the active air ventilation device directly into the headspace region that is above the surface of the water.

2. The method of claim 1, wherein the water conveyance device maintains a chemical gradient between the exterior air and the water such that volatile compounds are transferred from the water to the interior air.

3. The method of claim 1, wherein the exchanging of the air ses operating an air moving device of the active air ventilation device engaged with the water-storage tank to move the exterior air into the water-storage tank in a direction substantially across the surface of the water.

4. The method of claim 1, wherein the method does not incorporate an aeration step.

5. The method of claim 1, wherein the stored water contains an amount of volatile chemicals and the method automatically initiates when the amount of volatile als in the stored water exceeds a pre-determined amount.

6. The method of claim 5, wherein the method automatically stops when the amount of volatile als in the stored water drops below the pre-determined amount.

7. The method of claim 6, wherein the water stored in the tank comprises an initial amount of le chemicals and the pre-determined amount is about 5% of the initial amount.

8. The method of claim 6, wherein the water stored in the tank ses an initial amount of volatile chemicals and the pre-determined amount is about 15% of the initial amount.

9. The method of claim 1, wherein the tank has a floor and the water conveyance device is configured to exchange water at or toward the floor of the tank with water at or toward the water surface.

10. The method of claim 9, wherein the water conveyance device circulates water around the tank.

11. The method of claim 1, wherein the water ance device is completely submerged in the water when the tank is in use.

12. The method of claim 1, wherein the active air ventilation device comprises air vents that fluidly connect the air exterior of the water-storage tank to the headspace

13. The method of claim 12, wherein the active air ventilation device ses at least one screen that is positioned over at least one of the air vents.

14. The method of claim 1, wherein the active air ventilation device comprises an air moving device, wherein the air moving device is a fan. HG. "E