SYSTEMS AND METHODS FOR CONTROLLING WATERBORNE PATHOGENS

Abstract

Systems and methods to control colonization, amplification and/or growth of waterborne aerobic heterotrophic bacteria within potable water plumbing of a premises are provided, the premises having potable water plumbing having at least one point of use within the premises, the potable water plumbing being adapted to receive a potable water supply from a municipal water source. The systems and methods to control colonization, amplification, and/or growth of waterborne aerobic heterotrophic bacteria within cooling towers and evaporative condensers, recirculates system water through a deoxygenation device to reduce dissolved oxygen levels and prevent bacterial respiration within the heat exchanger and pressurized lines.

Claims

1. A method to control colonization, amplification and/or growth of waterborne aerobic heterotrophic bacteria within a water plumbing system of a premises comprising: (i) providing supply water from a municipal water source to the water plumbing system of the premises; (ii) passing the supply water from the municipal water source through a deoxygenation device to deoxygenate the water supply to at least hypoxic dissolved oxygen concentrations of less than 2.0 mg/L to thereby provide deoxygenated water to the water plumbing system of the premises.

2. The method according to claim 1, wherein step (ii) is practiced by deoxygenating the supply water to anoxic dissolved oxygen concentrations of less than 0.5 mg/L.

3. The method according to claim 1, wherein the water plumbing system comprises at least one of a fire suppression system, a cooling tower, a boiler, a water heater, a sink faucet, an ice machine, a drinking fountain and a hose bib.

4. The method according to claim 1, which further comprises passing the supply water through a water-pretreatment system positioned upstream of the deoxygenation device.

5. The method according to claim 4, wherein the water-pretreatment system comprises a sediment filter, an activated carbon filter and/or a water softener.

6. The method according to claim 1, wherein the water plumbing system of the premises includes a faucet for discharging potable water therefrom, and wherein the method further comprises providing an aerator at the faucet to aerate the potable water upon discharge from the potable water plumbing to re-oxygenate the water discharged through the faucet to a dissolved oxygen concentration of greater than 2.0 mg/L.

7. The method according to claim 6, wherein the aerator re-oxygenates the water discharged through the faucet to a dissolved oxygen concentration of between about 5 mg/L to about 15 mg/L.

8. The method according to claim 6, wherein the aerator re-oxygenates the water discharged through the faucet to a dissolved oxygen concentration of between about 8 mg/L to about 10 mg/L.

9. A system to control colonization, amplification and/or growth of waterborne aerobic heterotrophic bacteria within potable water plumbing of a premises comprising: (i) a premises having potable water plumbing having at least one point of use within the premises, the potable water plumbing being adapted to receive a potable water supply from a municipal water source; and (ii) a deoxygenation device positioned upstream of the premises plumbing to receive the potable water supply from the municipal water source so as to deoxygenate the potable water supply flowing through the deoxygenation device to at least hypoxic dissolved oxygen concentrations of less than 2.0 mg/L, wherein (iii) the potable water plumbing delivers the deoxygenated water to at least one point of use of the potable water plumbing of the premises.

10. The system according to claim 9, wherein the deoxygenation device deoxygenates the potable water supply to anoxic dissolved oxygen concentrations of less than 0.5 mg/L.

11. The system according to claim 9, wherein the potable water plumbing comprises at least one point of use selected from the group consisting of a fire suppression system, a cooling tower, a boiler, a water heater, a sink faucet, an ice machine, a drinking fountain and a hose bib.

12. The system according to claim 9, which further comprises a water-pretreatment system positioned upstream of the deoxygenation device so that the municipal water supply is passed through the water-pretreatment system before being passed through the deoxygenation device.

13. The system according to claim 12, wherein the water-pretreatment system comprises a sediment filter, an activated carbon filter and/or a water softener.

14. The system according to claim 9, wherein at least one point of use of the potable water plumbing of the premises includes a faucet for discharging potable water therefrom, and wherein the system further comprises an aerator provided at the faucet in fluid-communication with the deoxygenated potable water to thereby re-oxygenate the water discharged through the faucet to a dissolved oxygen concentration of greater than 2.0 mg/L.

15. The system according to claim 14, wherein the aerator re-oxygenates the water discharged through the faucet to a dissolved oxygen concentration of between about 5 mg/L to about 15 mg/L.

16. The system according to claim 14, wherein the aerator re-oxygenates the water discharged through the faucet to a dissolved oxygen concentration of between about 8 mg/L to about 10 mg/L.

17. A method to control colonization, amplification and/or growth of waterborne aerobic heterotrophic bacteria within a cooling tower or evaporative condenser comprising: (i) providing a water supply from a municipal water source, well, or surface water source to cooling tower or evaporative condenser; (ii) passing the water supply through a deoxygenation device to deoxygenate the potable water supply to at least hypoxic dissolved oxygen concentrations of less than 2.0 mg/L; and (iii) recirculating the system water through the deoxygenating device to achieve dissolved concentrations of less than 2.0 mg/L or less than 0.5 mg/L in the heat exchanger and circulation lines.

Description

BRIEF DESCRIPTION OF ACCOMPANYING DRAWINGS

[0016] The disclosed embodiments of the present invention will be better and more completely understood by referring to the following detailed description of exemplary non-limiting illustrative embodiments in conjunction with the drawings of which:

[0017] FIG. 1 is a schematic diagram showing an exemplary embodiment in accordance with the present invention;

[0018] FIG. 2 is a schematic diagram showing another exemplary embodiment in accordance with the present invention; and

[0019] FIG. 3 is a schematic diagram showing an exemplary embodiment of a cooling tower/evaporative condenser installation in accordance with the present invention.

DETAILED DESCRIPTION

[0020] In general, the embodiments disclosed herein will necessarily include a membrane contactor to remove oxygen from an incoming municipal water supply before it is distributed to fire-suppression systems, cooling towers, evaporative condensers, potable cold-water service, and water heaters or boilers so as to create at least a hypoxic (<2.0 mg/L dissolved oxygen) or anoxic (<0.5 mg/L dissolved oxygen) aqueous water source downstream of the contactor. Established bacterial biofilms and aerobic heterotrophic bacterial colonies will cease amplification, cellular respiration, and eventually become non-viable in such a hypoxic or anoxic water source. Aerobic heterotrophic bacteria, including Legionella and Pseudomonas, that are introduced from the incoming municipal water supply will thus not be able to colonize, amplify, metabolize, or establish biofilms within premise plumbing systems by virtue of the hypoxic or anoxic conditions of the water source downstream of the contactor. According to certain embodiments, the contactor will effect a downstream anoxic (<0.5 mg/L dissolved oxygen) water condition such that aerobic bacteria already in the plumbing systems will become metabolically dormant under such conditions.

[0021] Water with reduced dissolved oxygen concentrations may then be treated and used as untreated water would normally be. Installation of aerators at the point of water use (e.g., at water supply faucets where the water is discharged to the consumer) can re-introduce dissolved oxygen to improve perceived taste if desired. The aerator may therefore re-oxygenate the otherwise previously deoxygenated water at the point of discharge so that the discharged water has a dissolved oxygen concentration of greater than 2.0 mg/L, for example between about 5 mg/L to about 15 mg/L or between about 8 to about 10 mg/L. To ensure that membrane contactor performance is achieving desired results, an in-line real-time dissolved oxygen sensor can be installed in cold-water plumbing lines, hot water distribution lines, and recirculating utility water lines.

[0022] Accompanying FIG. 1 shows a system 10 which embodies the present invention. As shown, the system 10 will include a deoxygenation device 12 positioned to receive potable water from the municipal potable water supply 14. The deoxygenation device 12 thereby delivers deoxygenated water having a dissolved oxygen concentration of less than 2.0 mg/L to achieve hypoxic water conditions, or less than 0.5 mg/L to achieve anoxic water conditions to the potable water supply system (noted generally by reference numeral 16) within the premise building 18.

[0023] The system 10 depicted in FIG. 2 is similar to that depicted in FIG. 1 (and thus the same reference numerals have been employed for the same features) with the principal exception being that a water-pretreatment system 20 which may include a sediment filter, an activated carbon filter and/or a water softener, is installed in the potable water conduit from the municipal water supply 14 upstream of the deoxygenating device 12. The pretreatment system 20 may thus be advantageously employed so that sediment and/or other dissolved particulates do not affect the deoxygenation functions of the deoxygenation device 12.

[0024] A cooling tower/evaporative condenser installation 10 is depicted schematically in accompanying FIG. 3. As shown, the installation 10 is provided with a condenser 30 which is operatively supplied with cold water from a cooling tower 32. The condenser 30 is in heat-exchange relationship with an evaporator 34 positioned within a cooling loop 34a circulation of chilled water providing a heat-exchange medium to remove heat from the heat load 36. A chilled water pump 38 is provided so as to circulate the chilled water within the cooling loop 34a.

[0025] As is conventional, the cooling tower 32 operates to provide cold water in the basis 32a which provides a supply of cold water that is circulated within the loop 40 by the cold water pump 42. Make-up water is supplied to the basin 32a from the municipal water supply MWS through a sediment filter 44a and an activated carbon filter 44b. A deoxygenation device 46 is positioned in the circulation loop 40 so as to receive the cold water from the basin 32a of the cooling tower 32. The deoxygenation device 46 thereby delivers deoxygenated cold water having a dissolved oxygen concentration of less than 2.0 mg/L to achieve hypoxic water conditions, or less than 0.5 mg/L to achieve anoxic water conditions to the condenser 30 and thereby ensures that deoxygenated cold water circulates within the loop 40. If desired, a sedimentation filter 46a may be positioned upstream of the deoxygenation device 46 to remove particulates that may be present in the cold water within the loop 40.

[0026] Various modifications within the skill of those in the art may be envisioned. Therefore, while the invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not to be limited to the disclosed embodiment, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope thereof.